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Zeolite synthesis from municipal solid waste ash using fusion and hydrothermal treatment

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Title:
Zeolite synthesis from municipal solid waste ash using fusion and hydrothermal treatment
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English
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Sallam, Maysson
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University of South Florida
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MSW Ash
Zeolite A
Zeolite P1
glass
Unnamed zeolite
Dissertations, Academic -- Civil Engineering -- Doctoral -- USF
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theses   ( marcgt )
non-fiction   ( marcgt )

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Abstract:
ABSTRACT: This dissertation investigates the possibility of producing zeolites from municipal solid waste ash, MSW ash, by using hydrothermal treatment alone and by introducing fusion at 550 °C prior to hydrothermal treatment. The study was performed at different treatment conditions where silica/aluminum ratio of 13.9 and 2.5, hydroxide concentrations of 1.5N, 2.5N and 3.5N, temperatures at 100°C and 60 °C and time at 6, 24 and 72 hours were the major variables used to study zeolites synthesis process. The possibility of forming zeolites A, P1 and X was of particular interest in the present study. Factors, mechanism and modeling of zeolite A were investigated thoroughly in the present study. Zeolite synthesis process was evaluated using X-Ray diffraction to study different formed zeolite types and their chemical composition as well as their percentages. Morphological and physical characteristics of the produced zeolitic materials were evaluated by scanning electron microscopy, S EM, and cation exchange capacity property, CEC.The findings indicate that hydrothermal process did not succeed in producing significant amounts of zeolites. Consequently, the CEC of the produced zeolitic materials were much below the available commercial zeolite materials.Fusing the ash prior to hydrothermal treatment successfully produced sodium aluminum silicates and sodium silicates precursors to zeolite A formation. Fusion followed by hydrothermal treatment yielded significant amounts of zeolite A, at maximum value of 38.8% with CEC up to 245.0 meq/100g, which is within the range of commercially available zeolites. Experimental design analysis performed on zeolite A synthesis showed that zeolite A formation was reproducible and equation of interaction between different used conditions was established. Mechanism of zeolite A formation was concluded to be solution transport mediated process that involved both gel and solution interaction rather than being pure solution reaction or pu re gel transformation process. Solution super saturation and optimum silica/aluminum ratio were the driving force for nucleation of zeolite A.
Thesis:
Dissertation (Ph.D.)--University of South Florida, 2006.
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Includes bibliographical references.
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by Maysson Sallam.
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Document formatted into pages; contains 172 pages.
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Includes vita.

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oclc - 176629692
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Zeolite Synthesis from Municipal Solid Waste Ash Using Fusion and Hydrothermal Treatment by Maysson Sallam A dissertation submitted in partial fulfillment of the requirement s for the degree of Doctor of Philosophy Department of Civil and Envi ronmental Engineering College of Engineering University of South Florida Co-Major Professor: Robert P. Carnahan, Ph.D. Co-Major Professor: Abla Zayed, Ph.D. Sermin Sunol, Ph.D. Scott Campbell, Ph.D. Noreen Poor, Ph.D. Date of Approval: October 13, 2006 Keywords: MSW Ash, Zeolite A, Zeo lite P1, glass, Unnamed Zeolite Copyright 2006, Maysson Sallam

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DEDICATION To my father and mother, both of you kept me going through my whole life. To my sisters and brother I made it with your support.

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ACKNOWLEDGEMENTS I am indebted to both Dr. Robert P. Ca rnahan and Dr. Abla Zayed for their financial technical and scientific support dur ing the years of the study. A special thanks to Dr. Sermin Sunol for the valuable advises and the technical help she has provided during conducting the research. I would like to thank Anthony M. Greco from Marine Sciences for all the help he has provided during performi ng the scanning electron microscopy imaging process. A special thanks to Cherine Chehab for being patient with me during editing the dissertation. Also thanks to Bob Smith from engineering shop and Rafeal Urea from Ci vil Department for all the techni cal help they have provided during the years of my study. Thanks to Ingrid Hall, Jennifer Co llum and Jackie Alderman from the Civil Department and Catherine High from the Dean office for all the administrative support they have provided which made my years of study easier.

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TABLES OF CONTENTS LIST OF TABLES iv LIST OF FIGURES vii ABSTRACT xii CHAPTER 1 INTRODUCTION 1 1.1 Importance of the Research 1 1.2 Research Objectives 2 1.3 Dissertation Outline 4 CHAPTER 2 ZEOLITE SYNTHESIS: INTRODUCTION AND PREVIOUS RESEARCH 6 2.1 Background on Zeolite Synthe sis 7 2.2 Zeolite Synthesis from Different Silic a and Aluminum Sources 8 2.3 General Factors Affecting Zeolit e Synthesis 8 2.4 General Theories on the Mechanism of Zeolite Synthesis 8 2.5 Modeling of Zeolite Formati on Process 10 2.6 Zeolite Formation Stages 11 2.6.1 Induction 11 2.6.2 Nucleation 11 2.6.3 Crystallization 12 2.7 Zeolite Synthesis from Pure C hemical Compounds 12 2.8 Zeolite Synthesis from Coal Ash 13 2.9 Theory for the Mechanism of Zeolite Sy nthesis from Coal Ash 16 2.10 Previous Research Work on Zeolite Synthesis from Municipal Solid Waste Ash 16 CHAPTER 3 METHODLOGY 20 3.1 Samples Preparations and Experiment al Setups 20 3.1.1 Samples preparations 20 3.1.2 Experimental setups 21 3.1.2.1 Hydrothermal treatm ent 21 3.1.2.2 Fusion prior to hydrot hermal treatment 22 3.2 Instrumentation and Evaluatio n Techniques 26 3.2.1 Chemical analyses 26 3.2.2 X-ray diffraction analysis 26 3.2.3 Cation exchange capacity, CEC 26 i

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3.2.4 Zeolite percentage estimation 28 3.2.5 Scanning electron microsc opy, SEM 31 3.3 Experimental Design Analysi s 31 CHAPTER 4 RESULTS 33 4.1 Ash Composition 33 4.2 Hydrothermal Treatment 36 4.3 Fusion Prior to Hydrothermal Treatment 44 4.3.1 Hydrothermal treatment for fu sed ash at 1.5N 45 4.3.2 Hydrothermal treatment for fus ed ash at 2.5N 54 4.3.3 Hydrothermal treatment for fu sed ash at 3.5N 63 4.3.4 Summary of the results 72 4.4 Zeolite A Formation 73 4.5 Experimental Design Analysis and Modeling of Zeolite A Formation 83 CHAPTER 5 DISCUSSION 86 5.1 Hydrothermal Versus Fusion Prior to Hydrothermal Treatment 86 5.1.1 The effect of applying hydrot hermal treatment alone 86 5.1.2 Fusion prior to hydrothermal 91 5.1.2.1 Hydrothe rmal treatment at 100 0 C for fused ash 91 5.1.2.2 Hydrothe rmal treatment at 60 0 C for fused ash 105 5.1.3 Summary 113 5.2 Zeolite A Formation, Theory and Mechanism 114 5.2.1 The role of fusion versus hydrothermal in zeolite a format ion 116 5.2.2 Mechanism of zeolite a formation 120 5.3 Experimental Design Analysis, Modeling of Zeolite A Formation 123 5.3.1 Model constrains 124 5.3.2 Effect of hydroxide c oncentrations 124 5.3.3 Effect of temperatur e and time 127 CHAPTER 6 CONCLUSIONS 129 6.1 Hydrothermal Treatment of MSW Ash 129 6.2 Fusing MSW Ash Prior to Hydrothe rmal Treatment 130 6.3 Factors and Mechanism of Zeolite A Formation from MSW 134 6.4 Experimental Design An alysis and Modeling of Zeolite A Formation 137 ii

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CHAPTER 7 RECOMMENDATIONS 138 REFERENCES 142 APPENDICES 146 Appendix A: X-Ray Diffraction Para meters 147 Appendix B: Scanning Electron Micr oscopy 148 Appendix C: Chemical Co mposition of Different Ash Fractions 149 Appendix D: Statistical Analysis on Fused Ash 150 Appendix E: Linear Regression Analysis on Zeolite A Formation 162 Appendix F: Regression Analysis as a Function of N a 164 Appendix G: Yatess Algorithm Calculations 172 ABOUT THE AUTHOR End Page iii

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LIST OF TABLES Table 3.1 Theoretical values of the CEC for zeolite types of interest for this particular study. 27 Table 3.2 General matrix set up for yield percentages of zeolite A for samples treated with 1.5, 2.5 and 3.5 normality of sodium hydroxide. 32 Table 4.1 Chemical compositi on of ash shown for major and minor elements. 34 Table 4.2 Hydrothermal treat ment for the ash at 100 o C with sodium hy droxide concentration of 1.5N, silica/aluminum ratio is 13.9. 37 Table 4.3 Hydrothermal tr eatment for the ash at 100 o C with sodium hydroxide concentration of 1.5N, silica/aluminum ratio is 2. 5. 37 Table 4.4 Hydrothermal treatment for ash at 100 o C and sodium hydroxide concentration as2.5N, silica/aluminum ratio is 13.9. 38 Table 4.5 Hydrothermal treatment for ash at 100 o C and sodium hydroxide concentration as 2.5N, silica / aluminum ratio is 2.5. 38 Table 4.6 Phases produced as a result of subjecting the ash to fusion at 550 o C for 3 hours. 45 Table 4.7 Fused ash with 1.5N fo llowed by hydrot hermal treatment at 100 o C, silica/aluminum ratio is 13.9. 46 Table 4.8 Fused ash with 1.5N fo llowed by hydrot hermal treatment at 100 o C, silica/aluminum ratio is 2.5. 46 Table 4.9 Fused ash with 1.5N fo llowed by hydrot hermal treatment at 60 o C, silica/aluminum ratio is 13 .9. 51 iv

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Table 4.10 Fused ash with 1.5N fo llowed by hydrother mal treatment at 60 o C, silica/aluminum ratio is 2.5. 51 Table 4.11 Fused ash with 2.5N fo llowed by hydrot hermal treatment at 100 o C, silica/aluminum ratio is 13. 9. 55 Table 4.12 Fused ash with 2.5N fo llowed by hydrot hermal treatment at 100 o C, silica/aluminum ratio is 2.5. 55 Table 4.13 Fused ash with 2.5N fo llowed by hydrot hermal treatment at 60 o C, silica/aluminum ratio is 13.9. 60 Table 4.14 Fused ash with 2.5N fo llowed by hydrot hermal treatment at 60 o C, silica/aluminum ratio is 2.5. 60 Table 4.15 Fused ash with 3.5N fo llowed by hydrother mal treatment at 100 o C, silica/aluminum ratio is 13.9. 64 Table 4.16 Fused ash with 3.5N fo llowed by hydrother mal treatment at 100 o C, silica/aluminum ratio is 2.5. 64 Table 4.17 Fused ash with 3.5N fo llowed by hydrot hermal treatment at 60 o C, silica/aluminum ratio is 13.9. 69 Table 4.18 Fused ash with 3.5N fo llowed by hydrot hermal treatment at 60 o C, silica/aluminum ratio is 2.5. 69 Table 4.19 Summary for conditions used to perform Yatess algorithm analysis for cycle 1. 84 Table 4.20 Summary for conditions used to perform Yatess algorithm analysis for cycle 2. 84 Table C.1 Chemical compos ition of different ash fr action. 149 Table D.1 Statistical analysis for fused ash at 1.5N at 100 o C for 6 hours. Silica/aluminum ratio is 2.5. 150 Table D. 2 Statistical analysis for fused ash at 1.5N at 100 o C for 24 hours. Silica/aluminum ratio is 2.5. 151 Table D.3 Statistical analysis for fused ash at 1.5N at 60 o C for 6 hours. Silica/aluminum ratio is 2.5. 152 Table D.4 Statistical analysis for fused ash at 1.5N at 60 o C for 24 hours. Silica/aluminum ratio is 2.5. 153 v

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Table D.5 Statistical analysis for fused ash at 2.5N at 100 o C for 6 hours. Silica/aluminum ratio is 2.5. 154 Table D.6 Statistical analysis for fused ash at 2.5N at 100 o C for 24 hours. Silica/aluminum ratio is 2.5. 155 Table D.7 Statistical analysis for fused ash at 2.5N at 60 o C for 6 hours. Silica/aluminum ratio is 2.5. 156 Table D.8 Statistical analysis for fused ash at 2.5N at 60 o C for 24 hours. Silica/aluminum ratio is 2.5. 157 Table D.9 Statistical analysis for fused ash at 3.5N at 100 o C for 6 hours. Silica/aluminum ratio is 2.5. 158 Table D.10 Statistical analysis for fused ash at 3.5N at 100 o C for 24 hours. Silica/aluminum ratio is 2.5. 159 Table D.11 Statistical analysis for fused ash at 3.5N at 60 o C for 6 hours. Silica/aluminum rati o is 2.5. 160 Table D.12 Statistical analysis for fused ash at 3.5N at 60 o C for 24 hours. Silica/aluminum ratio is 2.5. 161 Table F.1 The resulted ratios for R squared values, R 2 a+1 / R 2 a, for adding N a to the proposed model. 164 Table F.2 The results of the final regression analysis showing equation coefficients and statistical analys is performed on the model at 95% confidence for N 6 166 Table F.3 A comparison between ex perimentally obtained yield values, Y, and the predicted yield. 167 Table G.1 Yatess algorithm analysis that was performed to determine the coefficients of the yield equation for 1.5N and 2.5N. 172 Table G.2 Yatess algorithm analysis that was performed to determine the coefficients of the yield equation for 2.5N and 3.5N. 172 vi

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LIST OF FIGURES Figure 2.1 Zeolite formation stages. 12 Figure 3.1 Schematic presentatio n for the steps followed in zeolite synthesis process under hydrothermal treatment. 23 Figure 3.2 Schematic presentatio n for the steps followed in zeolite synthesis process under hydrothermal treatment for fused ash. 24 Figure 3.3 Flow chart summary for different conditions used in the case of performing hydrothermal treatment alone and in the case of introducing fusion step prior to hydrothermal treatment. 25 Figure 4.1 X-ray diffraction patterns for non treated ash sample. 35 Figure 4.2 X-ray diffraction pattern obtained for the ash treated at 1.5N for 6, 24 and 72 hours with silica/aluminum ratio 13.9. 40 Figure 4.3 X-ray diffraction pattern obtained for the ash treated at 1.5N for 6, 24 and 72 hours with silica/aluminum ratio 2.5. 41 Figure 4.4 X-ray diffraction pattern obtained for the ash treated at 2.5N for 6, 24 and 72 hours with silica/aluminum ratio 13.9. 42 Figure 4.5 X-ray diffraction pa ttern obtained for the ash treated at 2.5N for 6, 24 and 72 hours with silica/aluminum ratio 2.5. 43 Figure 4.6 X-ray diffraction pattern obtained for fused ash at 550 0 C at 1.5N and hydrothermally treated at 100 0 C for 6, 24 and 72 hours with silica/aluminum ratio of 13.9. 47 vii

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Figure 4.7 X-ray diffraction pattern obtained for fused ash at 1.5N that was treated hydrothermally at 100 0 C for 6, 24 and 72 hours with silica/aluminum ratio of 2.5. 49 Figure 4.8 X-ray diffraction pattern obtained for fused ash at 1.5N that was treated hydrothermally at 60 0 C for 6, 24 and 72 hours with silica/aluminum ratio of 13.9. 52 Figure 4.9 X-ray diffraction pattern obtained for fused ash at 1.5N that was treated hydrothermally at 60 0 C for 6, 24 and 72 hours with silica/aluminum rati o of 2.5. 53 Figure 4.10 X-ray diffraction pattern obtained for fused ash at 550 0 C at 2.5N and hydrothermally treated at 100 0 C for 6, 24 and 72 hours with silica/aluminum ratio of 13.9. 56 Figure 4.11 X-ray diffraction pattern obtained for fused ash treated hydrothermally at 2.5N at 100 0 C for 6, 24 and 72 hours with Silica/aluminum ra tio of 2.5. 58 Figure 4.12 X-ray diffraction pa ttern obtained for fused ash treated hydrothermally at 2.5N at 60 0 C for 6, 24 and 72 hours with Silica/aluminum ratio of 13.9. 61 Figure 4.13 X-ray diffraction pa ttern obtained for fused ash treated hydrothermally at 2.5N at 60 0 C for 6, 24 and 72 hours with Silica/aluminum ratio of 2.5. 62 Figure 4.14 X-ray diffraction patte rn obtained for 3.5N fused ash at 500 o C treated hydrothermally treated fused ash at 100 o C for 6, 24 and 72 hours, with silica/aluminum ratio of 13.9. 65 Figure 4.15 X-ray diffraction pa ttern obtained for 3.5N fused ash hydrothermally treated fused ash at 100 o C for 6, 24 and 72 hours with Silica/aluminum ratio of 2.5. 67 Figure 4.16 X-ray diffraction pa ttern obtained for 3.5N fused ash hydrothermally treated fused ash at 60 o C for 6, 24 and 72 hours with silica/aluminum ratio of 13.9. 70 Figure 4.17 X-ray diffraction patte rn obtained for 3.5N fused ash hydrothermally treated fused ash at 100 o C for 6, 24 and 72 hours with silica/aluminum ratio of 2.5. 71 viii

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Figure 4.18 Zeolite A percentages t hat were formed at 1.5N, 2.5N and 3.5N fused ash for hydrothermal treatment at 60 0 C and 100 o C for 6, 24 and 72 hours. 74 Figure 4.19 CEC values for zeolite A obtained at different treatments of 1.5N, 2.5N and 3.5N fused ash for hydrothermal treatment at 60 0 C and 100 o C for 6, 24 and 72 hours. 74 Figure 4.20 SEM image for original ash showing sharp non-homogenous components. 75 Figure 4.21 Fused ash at 1.5 N at 100 o C. 76 Figure 4.22 Fused ash at 1.5N at 60 o C. Zeolite A formation at different crystallization periods. 78 Figure 4.23 Fused ash at 2.5N at 100 o C. 79 Figure 4.24 Fused ash at 2.5N at 60 o C. Zeolite A formation at different crystallization periods. 80 Figure 4.25 Fused as h at 3.5N at 100 o C. 81 Figure 4.26 Fused ash at 3.5N at 60 o C. Zeolite A formation at different crystallization periods. 82 Figure 5.1 Zeolite yield and CEC values produced for applying hydrothermal treatment at 1.5N at 100 0 C, at silica/aluminum ratio of 13.9. 88 Figure 5.2 Zeolite yield and CEC values produced for applying hydrothermal treatment at 1.5N at 100 0 C, at silica/aluminum ratio of 2.5. 88 Figure 5.3 Zeolite yield and CEC values produced for applying hydrothermal treatment at 2.5N at 100 0 C, at silica/aluminum ratio of 13. 9. 89 Figure 5.4 Zeolite yield and CEC values produced for applying Hydrothermal treatment at 2.5N at 100 0 C, at silica/aluminum ratio of 2.5. 89 Figure 5.5 Zeolits percentages and their CEC contribution for fused ash treated hydrothe rmally at 1.5N at 100 0 C for 6, 24 and 72 hours for silica/aluminum ratio of 13.9. 92 ix

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Figure 5.6 Zeolits percentages and their CEC contribution for fused ash treated hydrothermally at 1.5N at 100 0 C for 6, 24 and 72 hours for silica/ aluminum ra tio of 2.5. 94 Figure 5.7 Zeolites percentages and their CEC contribution for fused ash treated hydrot hermally at 2.5N at 100 0 C for 6, 24 and 72 hours for silica/ alumi num ratio of 13.9. 97 Figure 5.8 Zeolites percentages and their CEC contribution for fused ash treated hydrothe rmally at 2.5N at 100 0 C for 6, 24 and 72 hours for silica/aluminum ratio of 2.5. 98 Figure 5.9 Zeolites percentages and their CEC contribution for fused ash treated hydrot hermally at 3.5N at 100 0 C for 6, 24 and 72 hours for silica/alumi num ratio of 13.9. 101 Figure 5.10 Zeolites percent ages and their CEC contribution for fused ash treated hydrot hermally at 3.5N at 100 0 C for 6, 24 and 72 hours for silica/aluminum ratio of 2.5. 102 Figure 5.11 Structures of zeolite A and sodalite. 103 Figure 5.12 Unnamed zeolite, Na 8 Al 6 Si 6 O 24 (NO 2 )2.3H 2 O formation and its CEC values at 1.5N at 60 o C and silica/aluminum ratio of 13.9. 107 Figure 5.13 Zeolite formation and their CEC values at 1.5N at 60 o C and silica/aluminum ratio of 2.5. 107 Figure 5.14 Zeolite formation and their CEC values at 2.5N at 60 o C and silica/aluminum ratio of 13.9 108 Figure 5.15 Zeolite formation and their CEC values at 2.5N at 60 o C and Silica/aluminum ratio of 2.5. 109 Figure 5.16 Zeolite formation and their CEC values at 3.5N at 60 o C and silica/aluminum ratio of 13.9. 111 Figure 5.17 Zeolite formation and their CEC values at 3.5N at 60 o C and silica/aluminum ratio of 2.5. 111 Figure 5.18 SEM images for Zeolite A sequence of formation. 119 Figure 5.19 Zeolite A path of formation. 121 x

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Figure 5.20 Schematic pres entations for zeolite A formation process. 122 Figure 5.21 Normal probability plot for cycl e 1, for 1.5N and 2.5N. 125 Figure 5.22 Normal probability plot for cycl e 2, for 2.5N and 3.5N. 125 Figure F.1 R 2 values versus power increases for N in the proposed model. 164 xi

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ZEOLITE SYNTHESIS FROM MUNI CIPAL SOLID WASTE ASH USING FUSION AND HYDROTHERMAL TREATMENT Maysson Sallam ABSTRACT This dissertation investigates the po ssibility of produci ng zeolites from municipal solid wast e ash, MSW ash, by using hy drothermal treatment alone and by introducing fusion at 550 0 C prior to hydrothermal treatment. The study was performed at different treatment condition s where silica/alumi num ratio of 13.9 and 2.5, hydroxide concentrations of 1. 5N, 2.5N and 3.5N, temperatures at 100 o C and 60 0 C and time at 6, 24 and 72 hours were the major variables used to study zeolites synthesis process. T he possibility of forming zeolites A, P1 and X was of particular interest in the present study. Factors, mechanism and modeling of zeolite A were investigated thoroughly in the present study. Zeolite synthesis process was evaluated using X-Ray diffraction to study different formed zeolite types and their chemical co mposition as well as their percentages. Morphological and physical characteristi cs of the produced zeolitic materials were evaluated by scanning electron microscopy, SEM, and cation exchange capacity property, CEC. xii

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The findings indicate that hydrot hermal process did not succeed in producing significant amounts of zeolit es. Consequently, the CEC of the produced zeolitic materials were much below the available commercial zeolite materials. Fusing the ash prior to hydrotherma l treatment successfully produced sodium aluminum silicates and sodium silic ates precursors to zeolite A formation. Fusion followed by hydrotherma l treatment yielded significant amounts of zeolite A, at maximum value of 38.8% with CEC up to 245.0 meq/100g, which is within the range of commercially available ze olites. Experimental design analysis performed on zeolite A synthesis showed that zeolite A formation was reproducible and equation of interaction between differ ent used conditions was established. Mechanism of zeolite A formation was concluded to be solution transport mediated process that involved both gel and solution interaction rather than being pure solution reaction or pure gel tr ansformation process. Solution super saturation and optimum silica/aluminum rati o were the driving force for nucleation of zeolite A. xiii

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1 CHAPTER 1 INTRODUCTION 1.1 Importance of the Research In the United States, about 225 million tons of m unicipal solid waste are generated annually. One third of this waste is either recycled or composted. Landfilling or incinerat ion manages about 150 million tons of municipal solid wastes. Incineration is becoming a favor able option for many reasons including problems associated with landfil ling, excellent volume r eduction, energy recovery and revenues gained. Landfilling is faci ng increasing opposition by both regulatory and public agencies d ue to their drastic effect on the environment; in consequence, landfills in the United Stat es decreased from 8,000 in 1988 to 1,858 in 2001. In the Unit ed States, about 14% of gen erated waste, 86,000 tons, is incinerated yearly. Though incineration results in 70-90 % volume reduction of waste, a significant portion remains as as h. The remaining ash portion is usually divided into bottom ash fraction which accounts for 90% of the produce ash and fly ash fraction which accounts for only 10 % of the total ash portion. Concerns still exist for landfilling of the remaining ash. This generated interest in treating and reusing the ash. To date, only 5% of the produced ash is being utilized in the United States. The majority of applicati on has been in construction applications.

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2 Only recently, an innovative technol ogy proposed chemical conversion of the ash to produce zeolites material. The possibility of successfully producing zeolite from the ash is contributed to the fact that the ash has considerable fraction of silica and alum ina, which are the primar y elements required for building zeolite structure. This type of conversion is expected to increase the adsorption capacity of the as h due to the formation of z eolite minerals such as zeolite X, P and A within the ash matr ix, which in consequence increases the potential of using the ash as an adsorbent in so many different applications. The investigation on zeolite synthesis process from municipal solid waste ash is still in its early stages There is little work that has been done so far to address zeolite formation from municipal so lid waste ash. None of the previous work addressed the formation proce ss comprehensively to answer many questions regarding the types of zeolit e that could be possibly produced, the optimization of the process, mechanism and theory of the formation, and the possibility of modeling t he synthesis process. 1.1 Research Objectives The previous research work to synthesize zeolite from municipal solid waste ash was done by appl ying two different types of treatments. The first treatment included subjecting the ash to hydrothermal reaction alone under alkaline conditions and at relatively lo w temperatures. The outcome of this treatment did not produced ze olite of interest and the produced zeolitic materials were not of economical value, based on their adsorption prope rties. The second

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3 treatment included fusing the ash at high te mperatures as a pret reatment step to activate the ash particles then applyi ng the hydrothermal treatment on the fused ash. The second treatment produced better z eolitic materials such as zeolite X but unfortunately this proc ess was applied to the fl y ash fraction only which economically may not be of significance since fly ash fraction accounts for only 10% of the total produced ash. None of the previous research work examined zeolites X and A formation when treating total ash fraction by fusion and with adjusting silica to alumina ratio. The objectives and the approach for this dissertation are described below: Determining the types and quality of zeolites that will form when total ash is subjected to hydrotherma l reaction alone. The quality of the produced zeolite will be predic ted from the cation exchange capacity property of the produced zeol itic materials. The effect of adjusting silica to alumina ratio on the production of zeolite will also be addressed. Hydrothermal process will be performed at three different alkaline conditions and at two different temperature levels for various periods of time. Determining types of zeolite that will form due to fusing the total ash as a pre step to hydrotherma l reaction process. Silica to alumina ratio will be adjusted in this case too. Zeolite types produced in this case and their qual ity will be compared with those achieved by applying hydrothermal treatment alone.

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4 The focus in this case will be on the formation of zeolite X and A types. The mechanism of zeolite A formation will be concluded from used formation conditions and sc anning electron microscopy observations. Experimental design and regre ssion analysis will be performed on the results to model zeolite A formation process. 1.2 Dissertation Outline Chapter 2 provides background on zeolite synthesis and previous research work on zeolite synthesis from municipal solid waste ash. The background section includes introduction to zeolite synthesis from different silica and alumina sources, factors affecting zeolite synthesis process, theories on the mechanism of zeolite synthesis and avai lable models for zeolite synthesis process. In the previous research work section, general methods for the synthesis of zeolite are presented. Thes e methods include, fusion, hydrothermal and the combined method: fusion and hydrot hermal. This section also addresses the factors that controlling t he synthesis of zeolite from municipal solid waste ash and the synthesis of zeolite A. Chapter 3 describes the methodolog y followed during conducting the research which include samples preparatio n, description for the zeolite synthesis process for fusion and hydrothermal steps silica/Alumina ratio adjustment, and technique used to evaluate the results wh ich included X-Ray diffraction, cation exchange capacity, scanning electron micr oscopy and the experimental design.

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5 Chapter 4 presents the results includi ng, estimation techniques used for determination of zeolite yield which incl uded combined X-ray diffraction analysis and cation exchange capacity property. The chapter presents the results for zeolite yield from hydrot hermal treatment alone and zeo lite yield from combined method: fusion and hydrother mal. Details for the experimental design and regression analysis that were used to model zeolite A formation are also presented. Chapter 5 provides details discussi on on the estimation method used to determine zeolite yield using X-ray analysis versus yield estimation using cation exchange capacity property. T he chapter also thoroughly discusses the effect of introducing fusion step on the formation of zeolite, the mechanism of zeolite A type formation from municipal solid wast e ash and the effect of different used conditions on zeolite A type formation. The used conditions is this case include the effect of concentration, the effect of time, the effect of temperature, and the effect of adjusting Silica to Alumina ratio. The chapter finally discusses the experimental design analysis performed to predict the interaction model for zeolite A formation and present a propos ed equation for the formation process. Chapter 6 present the final conclusion s of the research including zeolite synthesis by hydrothermal treatment versus combined method: Fusion and hydrothermal, zeolite A type formation, the factors th at affected Zeolite A type formation and the mechanism of zeolite A formation and its modeling equation. In Chapter 7, a list of recommendations suggested for conducting further research work on the topic.

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6 CHAPTER 2 ZEOLITE SYNTHESIS: INTRODUCTION AND PREVIOUS RESEARCH Zeolite synthesis process using municipal solid wast e ash as a source for silica and alumina has not been addressed ex tensively in the pr evious literature. However, zeolite synthesis from other silica and alumina sources such as pure chemical compounds and coal ash has re ceived a considerable attention by researchers and there is a pool of li terature that addressed its formation mechanisms, kinetic and mode ling for some of these s ources. Therefore, the available information on zeolite synthesis from these other sources, especially from coals ash, can be used to explain and predict zeolite formation for other poorly investigated sources such munici pal solid waste ash. Consequently, this chapter is divided into two parts. The fi rst part presents an extensive review for zeolite formation processes, theories of formation, factors affecting synthesis process and available mode ling when pure chemicals or coal ash are used as a source for silica and alumina. Formation of two particular zeolite types, namely zeolites X and A, will be the focus of the discussion here since the formation of these types of zeolites is of interest for the present research work.

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7 The second part of this chapter will present previously investigated research work on zeolite synthesis from mu nicipal solid waste ash. In this part, general methods for the synthesis as well as the factors controlling the process will be addressed. Also, the possibilities of forming Zeolites X and A from municipal solid waste ash will be addressed in this part. 2.1 Background on Zeolite Synthesis Zeolites are hydrated alumina silicates. Their structure cons ists of primary building blocks of inorganic tetrahedrons of silicon and alumina oxides (Designated as TO4 atom). These atoms are strongly bonded together via oxygen bridges to form well-defined channels and cavities. Zeolites are negatively charged as a result of the subs titution of silica by alumina in the structure. Water molecules and cations, such as Na, K and Ca, are adsorbed on the pore surfaces. These cations balance the negatively charged zeolite structure and are exchangeable species (Davis and Lobo, 1992). Zeolites can be synthesized from different sources and ther e are general factors that affect their formation, these sources and factor s are described briefly below. Two main groups have been categorized for zeolites based on their Si/Al ratio and main applications. These groups in clude 1) high silica to alumina ratio, which has a large structure and used mainly as catalysts, an example of such types is ZSM-5 zeolite 2) medium to low si lica to alumina ratio of fairly medium to small structures and whic h are used mainly as adsorbents and cation exchangers, such types include Fauj asite (X and Y types), Zeolite A.

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8 2.2 Zeolite Synthesis from Diffe rent Silica and Alumina Sources Simply, any source that can provide a reactive form of silica and alumina can be used to synthesize zeolite under t hermal high alkaline conditions. Zeolite has been synthesized massively from pure silica and alumina chemical compounds, such as sodium silicate an d sodium aluminates. Other sources including natural clay and fired coal ash have been also investigated. 2.3 General Factors Affe cting Zeolite Synthesis Regardless of the source, method or type of zeolite to be produced, important factors that affe ct zeolite synthesis process can be listed as follow: Silica/alumina ratio. Crystallization time. Crystallization temperature. Aging or maturation period. Stirring or agitation. The presence of alkali, such as Na and K and presence of impurities. Alkalinity of the solution; hi gh pH is required, between10-13. 2.4 General Theories on the Mec hanism of Zeolite Synthesis In general, there are two existing theories describing the formation process of zeolites as detailed below:

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9 The first theory is possible crystalliz ation from the mother liquor of dissolved species. Dissolved species include SiOH4 and AlOH4 (Marui et. al., 2002). This theory can be used to explain zeolite formation using pure chemical compounds but it is not suit able to explain zeolite formation from coal ash or municipal solid waste ash since these syst ems may have complex solid phases. The second theory focused mainly on the importance of forming amorphous aluminosillicate gel that acts as a precursor for zeolite nuclei formation which followed by crystal growth the crystallization in this case was described to form at the inte rface between the ge l and the solution. In this theory it is believed that the aluminosillicate gel transforms into z eolite nuclei then the formed nuclei either migrate to the solution to continue growth or it may continue its growth at the surface of the gel parti cles (Dutta and Bronic; 1994, Sheikh and Jones; 1996, Nikolakis et. al.; 1998, Cundy and Cox; 2003). Antonic and Subotic, 1997, 1998 and 1999, studied the effect of SiO4/Al2O3 ratio of the gel and solu tion and the effect of alkali on zeolite formation, namely zeolite A. They argued that SiO4/Al2O3 ratio of the gel but not of the solution is the most important factor that dete rmines the type and composition of formed zeolit e. They stated that SiO4/Al2O3 ratio of the solution affects only the rate of cryst allization but not the type of formed zeolite. Also, they argued that alkalinity of t he reaction mixture affect t he kinetics of the gelzeolite and zeolite-zeolite transformation since the presence of hydroxyl ion in reaction mixture determines the concentrations of reactive aluminat es, silicates and aluminosillicate species due to the fact t hat the Si-O-AL bridge is more inert to

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10 hydroxyl attack than the Si-O-Si bridge. Consequently, the final ratio of Si/Al in the gel upon its formation is actually re lated to the alkalinity of the reacted system. Finally, regardless of what type of mechanism is involved in the synthesis process, the driving force for t he synthesis to occur is always attributed to super saturation and concentration gr adient of silica and alumina in the solution or the gel. Concentration gradient usually triggers nucleation stage. The effect of gel formation theory on the zeolite formation mechanism was used to explain zeolite formation process using chemical reagents. For zeolite synthesis from coal ash or municipal so lid waste ash, adopting the role of gel formation theory seems to provide bette r explanation for the mechanism of zeolite formation from such sources. 2.5 Modeling of Zeolite Formation Process Many mathematical models were dev eloped to explain the kinetics of zeolite formation from pure chemical r eagent (Sheikh and Jones; 1996, Nikolakis et. al. 1998). Such models included the us e of classic nucleation theory, mass population modeling, and gel microstructu re. These models were possible to formulate since the modeled systems incl ude only simple system of reactants and gel. Unfortunately, these models ca nnot be used to study the kinetics of zeolite formation for systems that inclu de complex starting materials such as municipal solid waste ash. Since zeolite formation is considered in general as an optimization process, model ing such a process based on experimental design using n variables and with applying r egression analysis approach could be the

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11 appropriate approach to study and model such process, especially when studying zeolite formation from sources such as municipal solid waste ash. Tannous et. al., 1985, used such approach to model the effect of n= three different variables, or factors, including SiO4/Al2O3 ratio in the gel, ageing period and crystallization time on zeo lite faujasite yield. His ap proach was to use linear regression analysis using the residual vari ance method to check the produced model. His model was based on segmenti ng the variables in three different cycles of small interval levels. His approac h was perfect to study the effect of each factor on the yield for each cycle se parately; the reason that made linear regression approach suitable in this case was that linearity can be assumed for small segments. 2.6 Zeolite Formation Stages In general, the crystallization curve of zeolite has been described in the literature to include three stages with an Sshape (Budd et. al; 1994, Nikolakis et. al., 1998). Figure 2.1 illustr ates the general crystalliz ation curve and nucleation curve. The three stages of crystallization are: 2.6.1 Induction In the induction zone no zeolite forma tion will occur, only early stages of nucleation can occur in this stage. 2.6.2 Nucleation In the nucleation stage di fferent types of zeolites will start to form. Which type should be formed will depend on the Si/A l ratio as well as the temperature

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12 and alkali content in the soluti on. In this stage the cryst allization process will start and crystal growth will increase linear ly as the nucleation proceeds. 2.6.3 Crystallization In the crystallization stage, or crystal growth period, the growth curve will continue to increase linearly with time till the silica or alumina source is depleted then the crystal growth will terminate. The nucleation stage is found to be the critical stage in zeo lite formation process. Ti me Figure 2.1 Zeolite formation stages. 2.7 Zeolite Synthesis from Pure Chemical Compounds Many different types of zeolites were synthesized from pure chemical reagents. Among these different zeolite types only zeolites X, A, P and sodalite formation will be discussed here. The zeo lite formation process is multiphase, meta-stable and subject to transforma tion from one phase to another during Cr y stal Growth Curve Nucleation Curve

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13 synthesis. This transformation mo stly depends on solution SiO4/Al2O3 ratio, hydroxide concentration and cr ystallization time (Kostinko, 1983). For example, zeolite A and X tend to transform into zeolite P upon prolonged reaction time and at the same hydroxide concentration (Subot ic et. al. 1985, Grujic et. al. ; 1989, Krznaric et. al.; 2003). On the other hand, zeolite A is known to transform into sodalite and hydroxy-soda lite structure at a high hydroxide concentration (Subotic et. al. 1985, Grujic et. al. ; 1989 ). Also it was found that zeolite A and X usually coexist in the same system at certain SiO4/Al2O3 ratio (Kostinko, 1982 and 1983, Traa and Thompson; 2002). Finally it was reported that Zeolite X tends to transform into zeolite A (Kostink o, 1983). In general it was found that zeolite A formation requires lowered SiO4/Al2O3 ratio and higher hydroxide concentration while at high hydroxide c oncentrations and prolonged reaction time zeolite A and X tend to change into Sodalite structure and finally at low hydroxide concentration and prolong reaction time both zeolites A and X tend to transform into zeolite P. 2.8 Zeolite Synthesis from Coal Ash Zeolite synthesis from coal ash st arted in 1985 by using conventional hydrothermal method. Different types of zeolites were formed either sole or coexisting due hydrothermal reaction. Zeolites produced form hydrothermal treatment of coal ash were zeolite P, X, A, sodalite and hydroxyl Sodalite (Shih and Chang; 1996, Querol et. al .; 1997, Paul. et. al.; 1998, Scott. et. al.; 2001). In general, the findings of most of the c onducted research work showed that

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14 zeolites A and X coexist in most cases an d they tend to transform into zeolite P at prolong reaction time. Also, it was not iced that at high temperatures, above 900C, and high sodium hydroxide co ncentrations, 3N and above, and at prolonged reaction time zeol ite A (Stamboliev et. al., 1985) and P (Murayama, et. al., 2002) tend to transform in to sodalite structure. Tanaka et. al., 2002, 2002, 2003 and 2004 conduct a series of experiments on coal ash to control produc tion of zeolite X and A. Their work showed that by adjusting silica to alumi na ratio by adding sodium aluminates to fly ash, it is possible to direct the reac tion toward forming certain type of zeolite. He found that at SiO4/Al2O3 < 2.5 zeolite A was formed and at SiO4/Al2O3 between 7.3 -13.2 single phase of zeolite X is possible to form, his experiments were conducted at 85 0C and curing time of 72 hours. The cation exchange capacity, CE C, of the produced zeolites from hydrothermal treatment was in the r ange of 185 to 346 meq/100g for zeolite P and hydroxyl sodalite (Lin and His ; 1995, Singer and Berkgaut; 1995, Steenbruggen and Hollman; 1998, Scott et. al.; 2001, Juan et. al., 2002). It was noticed that to achieve high CEC of zeolite P the ash has to be treated at high sodium hydroxide concentration, 4N and higher, for long period of time, more than 48 hours. The CEC of the produced zeolite A type by hydrothermal method did not exceed 86 meq/100g (Shi h and Chang, 1996). Starting in 1993, an attempts to in crease the activity of the ash by dissolving refractory particl es to form zeolite have been made by applying two steps of treatment to the ash, which includes a fusi on step at high temperature

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15 (between 500-600 0C) followed by a second step of hydrothermal reaction. This process proved to increase the activity of the ash and yields higher percentages fractions of zeolites, especially Faujas ite types, X and Y (B erkgaut and Singer; 1996, Chang and Shih; 1998, Rayalu et. al.; 2000 and Poole; 2004). Mostly, medium to small structures with low Si/Al ratio were formed when subjecting ash to react under alkali conditi ons. Faujasite, zeolite X an d Y types, zeolite A, Na-P and gismondine, sodalite, hydroxysoda lites, and chabasite are the most prevailing zeolites types that has been formed from coal ash. The required hydrothermal treatment peri od to produce such zeolites ranges between 12 to 72 hours. Berkgaut and Singer, 1996, succeeded in synthes izing 40% of zeolite P from fly ash with CEC of 250 meq/100 g by apply ing fusion step at 550 0C followed by hydrotherma l treatment at 100 0C for 12 hours. The studies that have been done recently by Poole, 2004, on coal fly ash to produce zeolites proved that pretreatment wit h fusion prior to the hydrot hermal step has effectively enhanced the quality of produc ed zeolite X. He used coal fly ash with molar SiO4/Al2O3 ratio of 3.7 and aging for 24 hour s after the fusion step at sodium hydroxide concentration of 1.2N, then he treated the samples hydrothermally at 90 0C with a curing period of 24 hours. T he CEC of the produced zeolitic materials has improved from 120 meq/ 100g for only hydrothermally treated ash up to 200 meq/100g for fused ash.

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16 2.9 Theory for the Mechanism of Zeolite Synthesis from Coal Ash Recent theory for Zeolite synthesis from ash has been provided by Murayama et. al., 2002 and 2003. His theory was based on the formation of amorphous aluminosillicate gel on the solid particles under high alkaline conditions followed by crystallization of zeolite due to the reaction between the gel and the alkali or dissolv ed species in the mother liquor solution. This theory concluded for zeolite synthesis proce ss using the hydrothermal method and it was based on type of zeolit e produced as a function of time and by following the growth trend as observed in scanning el ectron microscopy images. Similarly, Poole, 2004, explains zeolite formation to be due to the re action between the alkali metal in solution and the dissolved silicate and aluminates species that were released from the aluminosillicate gel which was formed during the fusion step. He argued that the formation of t he gel in the fusion step enhanced zeolite formation because the gel provided enough active forms of silicates and aluminates species that initia te zeolite nucleation. 2.10 Previous Research Work on Zeolit e Synthesis from Municipal Solid Waste Ash The little available research work on zeolite synthesis fr om municipal solid waste ash, MSW, involved mostly treati ng the fly ash portion of the waste ash. One of the first trials on this subject was published by Yang and Yang in 1998. Yang and Yang synthesized zeolite by us ing the hydrothermal method. The conditions used in their experiments included operating temperatures in the

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17 range between 90 and 250 0C, sodium hydroxide concentr ations in the range of 1 to 6 normality, N, and crystallizati on time between 12 and 72 hours. SiO4/Al2O3 ratio used in this work was 3.6. Their experiments indicated that 1N sodium hydroxide concentration was not high e nough to initiate zeolites structure formation, but as the concentrations were increased, between 2N and 4N, this was optimum for zeolite formation. The types of zeolites that were formed were mainly gismondine and sodium alumina silicate hydrate ( unnamed zeolites). Zeolite X was observed to form when operating temperatures were 1500C and 1900C at 3.5N and for crystallization time in the range of 36 to 72 hours. The authors did not provide any qua ntification for the different types of zeolites that were formed but they indicated that the amount of produced zeolite X was minimal as indicated from X-Ray di ffraction analysis. The cation exchange capacity, CEC, of the produced zeolites di d not exceed 64 meq/ 100g in this case. The maximum CEC value obtained from t he zeolitic ash materials produced was very low compare to the commercial z eolites which have CEC values in the range of 200-300 meq/100g. Penilla et. al., 2003, treated MSW botto m ash fraction using hydrothermal treatment at operati on temperature of 500C to 2000C, sodium hydroxide concentration of 1N, crystallizatio n time of 12 hours and with SiO4/Al2O3 ratio of 3.0. The used normality in this case was very low and no significant zeolite was produced. Similarly, Kargbo, 2004 attempted to hydrothermally treat the total ash (i.e. bottom and fly ash mixture) to produce zeolite. The produced zeolite in this case was mainly sodalite octahydrate whic h is poorly crystalline, as indicated

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18 from the X-ray diffraction analysis. Zeolit e of faujasite stru cture was formed in minor amounts. There was no information presented by the author on the quality of the produced zeolitic materials and th e presented X-ray results have indicated the presence of highly amorphous material s as a result of using hydrothermal treatment. This indicated t hat treating the total ash by just using hydrothermal method did not seem to provide the formation of good quality zeolite. Zeolite synthesis from the MSW fly ash by combined fusion followed by hydrothermal treatment was conducted by Myake et. al., 2002. The fly ash was first treated with acid to reduce calcium content in the ash then the treated ash was subjected to hydrothermal treatment at operating temp eratures between from 60 -1800C, sodium hydroxide concentration of 0.5-3.5N and reaction time between 10 -48 hours. The pr oduced zeolites observed in this case were zeolite A, zeolite P and sodalite. Z eolite A and zeolite P coexist ed in this case and their formation was optimum at an o perating temperature of 800C, sodium hydroxide concentration of 2N and at crystal lization time of 20 hours. SiO4/Al2O3 ratio used in this work was 2.7. It was noticed that as crystallizat ion temperature and sodium hydroxide concentrati on increases zeolite A tend to transform into zeolite P and sodalite; these results are in agr eement with those obtained when zeolite was synthesized from coal ash. At temperature higher than 1200C sodalite was the only zeolite type observed to be form ed. The maximum CE C value obtained in this case was 109.9 meq/100g. The CEC of the produced zeolite materials is still lower than the commercial zeolite.

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19 The conclusions of previous research work show that the attempt to produce zeolite materials from MSW ash using hydrothermal treatment process alone is not enough to dissolute all the refrac tory components in the ash, such as quartz and alumina sources. It seems that introducing a fusion step is an essential step to ensure dissolution of the ash particles and to ensure the formation of gel materials that are nec essary for the nucleation of zeolite materials such as zeolite A. In addition, none of the previous work addressed the effect and the importance of producing gel materials from the ash as a pre step for zeolite crystallization. The only wo rk that has been done on the ash by applying fusion was performed on the fly as h portion only which is not enough to provide the ultimate solution for solving t he problem of ash disposal in landfills. Also none of the previous work a ttempted to quantify the amounts of each produced zeolite or their c ontribution to the total CEC of the ash materials. Finally, explaining the mechanism and modeling of zeolite production from municipal solid waste ash using such tr eatments were not addressed at all by any of the authors involv ed in such work.

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20 CHAPTER 3 METHODLOGY This chapter presents detailed descriptions for techniques, instrumentations, chemicals and experimen tal design setups used in the present research work to evaluate the synthesis process of zeolite fr om municipal solid waste ash. This chapter is divided into three main sections, section one includes description for samples preparations and experimental procedures. The experimental methods include detailed presentation for the procedures followed in the present study to synthesize zeolite from municipal solid waste ash as well as different conditions used during the syn thesis process. Section two presents the instrumentations tec hniques used to evaluate t he results obtained for each studied case. Finally, section three focuses on the experimental design techniques followed to model and study zeolite A formation and the effects of different used conditions on the formation of zeolite A. 3.1 Samples Preparations and Experimental Setups 3.1.1 Samples preparations A sample of municipal solid waste ash, MSW, was obtained from a local incinerator in Panama City, Florida. The sample was dried in fisher isothermal

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21 temperature oven at 110 oC then milled until 80% of the sample passed through 425-micrometer sieve. The sieved samples were then divided into two portions, one portion was treated hydrothermally alone and the se cond portion was subjected to fusion prior to hydrotherma l reaction as described in the following section. 3.1.2 Experimental setups Zeolite synthesis was studied at different conditions by varying silica/alumina ratio, temper ature, time and sodium hydroxide concentration in the reaction solution. Silica/alumina ra tio was adjusted by adding reagent grade sodium aluminates, NaAlO.xH2O during hydrothermal reaction. Two different types of experiments were performed to synthesize zeolite from MSW ash as described below. 3.1.2.1 Hydrothermal treatment Zeolite synthesis process was perfo rmed by placing 15 grams of ash samples in a 150 ml plastic bottle then 150 ml of nano-pure water was added to the ash samples to obtain solid/ liquid ra tio of 10, sodium hy droxide was added in different ratios to obtain 1.5N and 2.5N solutions. Then the bottles were sealed and placed in a conventional oven that was maintained either at 60 0C or at 100 0C for different periods of times includi ng 6, 24 and 72 hours. Co nditions that are mentioned above were used for another set of ash samples but in this case silica/alumina ratio was adjust ed by adding sodium aluminates directly to reaction solution.

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22 After the hydrothermal process is co mpleted the reacting solution was decanted and samples were washed three times with nano-pure water, the supernatant was separated from samples in each case by centrifuge. 3.1.2.2 Fusion prior to hydrothermal treatment In order to insure dissolution of t he refractory ash particles, the ash samples were subjected to fusion prior to the hydrothermal reaction step. The fusion step was performed by placing as h, water and sodium hydroxide to a plastic bottle to obtain 1.5N, 2.5N and 3.5N solutions, then the samples were placed in a furnace maintained at 550oC for 3 hours. Then, 15 grams of fused ash samples were placed in a 150 ml pl astic bottle with 15 0 ml of nano-pure water to obtain solid/ liquid ratio of 10, the bottles were then sealed and placed in a conventional oven that wa s maintained either at 600C or at 1000C for different periods of times including 6, 24 and 72 hours. The above mentioned conditions were used for another set of fused ash sa mples but in this case silica/alumina ratio was adjusted by again adding analyti cal grade sodium aluminates to the reaction solution. After the fused sa mples were treated hydrothermally, the reaction solution was decanted and sample s were washed three times with nanopure water; the supernatant was separat ed from samples in each case by centrifugation. Figures 3. 1 and 3.2 show schematic pr esentation for the steps followed in zeolite synthesis process under hydrothermal treatment without and with fusion, respectively. Figure 3.3 pres ents a flow chart summary for different conditions used for both cases when hydr othermal treatment was performed and in the case when fusion was perform ed prior to hydrothermal treatment.

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23 Milling Hydrothermal reaction Oven, 100 oC and 60 0C Figures 3.1 Schematic presentation for the st eps followed in zeolite synthesis process under hydrothermal treatment. Dried Ash Sample Sieving to pass through 425 m Solution includes: Sodium hydroxide + Ash (Silica/alumina ratio = 13.9) Solution includes: Sodium hydroxide + Ash + Sodium aluminates (Silica/alumina ratio = 2.5) Washing + Centrifuge + drying at originally used reaction temperature

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24 Fusion Furnace, at 550 0C Hydrothermal Oven, 100 oC and 60 0C Figures 3.2 Schematic presentation for the st eps followed in zeolite synthesis process under hydrothermal treatment for fused ash. Dried Ash Sample Sieving to pass through 425 m Fused ash Solution includes: Sodium hydroxide + Ash (Silica/alumina ratio = 13.9) Solution includes: Sodium hydroxide + Ash + Sodium aluminates (Silica/alumina ratio = 2.5) Washing + Centrifuge + drying at originally used reaction temperature

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ASH SAMPLE No fusion, nNaOH Fusion at 550 0C with nNaOH (Dissolution stage) Hydrothermal (Crystallization Stage) Hydrothermal (Crystallization stage) n= 1.5 N NaOH n= 2.5 N NaOH n= 3.5 N NaOH Without Si/Al With Si/Al Without Si/Al With Si/Al Without Si/Al With Si/Al Adjustment Adjustment Adjustment Adjustment Adjustment Adjustment 100 oC 60 oC 100 oC 60 oC 100 oC 60 oC 100 oC 60 oC 100 oC 60 oC 100 oC 60 oC Crystallization time 6, 24 and 72hours Figure 3.3 Flow chart summary for different conditions used in the case of performing hydrothermal treatment alone and in the case of introducing fusion step prior to hydrothermal treatment. 25

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26 3.2 Instrumentation an d Evaluation Techniques The chemical analysis was per formed on digested untreated ash; digestion was performed by dissolving th e ash using analytical grade strong acids including hydrofluoric acid and nitric acid. Zeolite phase formation and the physical properties of the produced zeolitic materials was evaluated using X-Ray diffraction analysis, scanning electron micr oscopy and cation exchange capacity property. 3.2.1 Chemical analyses The chemical analysis of the untreated ash was performed using inductively coupled plasma, ICP. Th e analysis was performed for major and minor elements including Si, Al, Mg, Ca Na, K, Fe, Mn, Cu, Zn Ti and P. 3.2.2 X-Ray diffraction analysis Mineralogical compositions for the untreated and treat ed samples were evaluated primarily by X-Ray di ffraction technique using Cu-k radiation (Appendix A) and crystalline ti tanium oxide (IV), TiO2 (< 5 micron, 99.9+%), as an internal standard. The percentage of th e produced zeolites materials were calculated using two different techniqu es. The first technique was based on calculating the integrated areas under th e X-ray diffraction peaks using Profit software. The second method combined bo th X-Ray diffraction pattern and cation exchange property as explained in details in section 3.2.4. 3.2.3 Cation exchange capacity, CEC Zeolites are characterized by cationic exchange capacity which is the results of the negative char ges that exist within the channels of the zeolite

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27 framework structure. These negative charges resulted fr om the substitution of silica by alumina in the tetrahedral primary building block of the zeolite structure. The cation exchange capacit y of the zeolites is directly proportional to the amounts of zeolites present in a materi al, either as a pur e phase or imbedded in a matrix with other impurities, so as the amounts of zeo lite increase the CEC increases in a linear fashion. Cation ex change capacity of zeolite materials is usually calculated in m illiequivalent per hundred gram s sample, meq/100g, and its values vary from one zeolite type to another depending on the chemical composition of the zeolite. Table 3.1 presents the theor etical values of the CEC for zeolite types of interest for this particular study. The linear relationship between the amounts of zeo lite and its CEC made it possible to estimate the amounts of zeolite in any materials based on its CEC values. Table 3.1 Theoretical values of the CEC for zeolite types of interest for this particular study. Zeolite name Cation Exchange Capacity ( meq/100g) Zeolite A 547.0 Sodalite 828.0 Zk-14 384.0 Zeolite P1 458.0 Zeolite P 351.0 Unnamed zeolite Sodium aluminum silicate nitrate hydrate 770.0 Unnamed zeolite Sodium aluminum silicate nitrate 806.0

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28 Many different cations can occupy the negatively charged sites of the zeolite. Sodium, calcium and potassium are the main exchangeable cations found to occupy these negatively charged sites. Ammonia, NH4 +, analytical grade, can easily exchange these cations at super saturation conditions. The cation exchange capacity of the zeolites produced in the present study was determined by using sodiumammonium acetate method number 9081 described in the Solid Waste Test Methods (SW846). The cation exch ange experiment was performed by adding high concentration of pure sodium acetate to the ash to insure that sodium is the on ly cation that occupies all zeolite sites present in the ash, and then the sample was washed with isopropanol alcohol, analytical grade, to remove any excess of sodium acet ate. The sodium z eolite form then was mixed with high concentration of ammoni um acetate to exch ange and extract the sodium ions. The amounts of extracted s odium ions, which represent the cationic capacity of the ash, were then determined by using sodium pr obe that has been standardized with four points at different s odium hydroxide concentrations. In the case of conditions where zeolite A was formed, a tr iplicate of CEC experiment was performed for each condition to insure reproducibility. 3.2.4 Zeolite percentage estimation The percentages of the formed zeolites were calculated using two different methods. The first method depended on ca lculating the area under the peaks obtained from the X-ray diffraction using pr ofit software. The calculated area is then normalized with respect to the area of an internal standard and the sum of total areas of present phases are calculat ed and the fractional percentage is then

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29 determined relative to the total areas. The second method combined both X-Ray diffraction profit analysis with cation ex change capacity values to estimate CEC contribution and the amount s of zeolite produced in each case. There are two reasons for using the co mbined method to estimate zeolite percentages and their CEC contribut ion. First, it is most likely that more than one zeolite phase will appear as the ash is tr eated, which makes it difficult to know the exact CEC contribution of each zeol ite phase since the CEC experiment provides the total CEC of the produced zeolitic material regardless of what type of zeolite is present. Se cond, the X-ray analysis alone could provide false percentile results since ar ea under the X-ray profile used to estimate zeolite percentage is strongly related to the physi cal properties, such as grain size and degree of crystallinity, of t he detected phases more than being a direct mass to mass or volume to volume relationship. Meaning if two phases are present in the same sample with significant variation in th eir particles size, the one that is larger or has higher variation in its particles si ze will show higher intensity or broadness in the X-ray peak which may result in higher estimation for that phase percentage. This is of concern in this particular study since the presence of non zeolitic phases such as quartz and calcite can result in false results in the percentages of different phases becaus e these two phases will have larger particle sizes than zeolite phases. Therefore, it is important to use a method that combines X-ray quantitative technique a nd total CEC value to provide better estimation for the amounts and the CEC contributions of each zeolite phase formed in the total ash. The CEC contri bution of each produced zeolite phase

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30 was determined by constructing linear re lationships between zeolite percentage fractions calculated from the X-Ray di ffraction analysis and actual total CEC determined experimentally. This estimate s the CEC contribution of two produced zeolite phases that were formed coex isting at two different conditions as described in equations 3.1 and 3.2 as follows: a1A1 + b1B1 = X total (3.1) a2A2 + b2 B2 = X total (3.2) where: a1and b1: Zeolite phases fractions as determined by X-ray diffraction pa ttern at used conditions 1. A1and B1: CEC contribution of zeolite A phase to be determined at used conditions 1. a2 and b2: Zeolite phases fractions as determined by X-Ray diffraction pa ttern at used conditions 2. A2and B2: CEC contribution of zeolite B2 phase to be determined at used conditions 2. As the CEC contribution for zeolit es A and B is determined, their percentages can be calculated by using th e theoretical values of the CEC for each zeolite types, shown in Table 3, as follows: A % = CEC A X100 CECTheoretical

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31 3.2.5 Scanning electron microscopy, SEM The morphology and crystal size of the non-treated and treated ash were studied by using Scanning Electron Micr oscopy Images (Appendix B). Gel and zeolite formation stages and mechanism of formation were assisted through observations of the SEM images. 3.3 Experimental Design Analysis Regression and Yatess Algorithm anal ysis were performed, using 23 experimental design analysis(Box et al., 1978), to study the effects and interactions of different conditions used on the nucleation and fo rmation of zeolite A. The effect of sodium hydroxide conc entration (N), temperature (T) and time of crystallization (t) were st udied at two levels. Lower concentration, temperature and crystallization time were denoted by while higher concentration, temperature and crystallization time were denoted +, and the measured response in this case was the yield percent ages of zeolite A; the yield value used was an average of triplicate samples. Tabl e 3.2 shows the general matrix setup for the experimental design that is used as a base for regression and Yatess Algorithm analysis. The general forma t for interactions between the used variables is described in equation 3.3 as follows: Yi = a +bN + cNt + dt + eT + fN T + gTt + hNTt (3.3) where: Yi: is zeolite yield. a: intercept.

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32 b,c,d,e,f,g and h: Equation coefficients. N: Sodium hydroxide concentration. t: Time, hours. T: Temperature, oC. Table 3.2 General matrix set up for yield percentages of zeolite A for samples treated with 1.5, 2.5 and 3.5 normality of sodium hydroxide. N T T % yield Effect Coefficient Y1 Average A + Y2 N B + Y3 T C + + Y4 Nt D + Y5 T E + + Y6 NT F + + Y7 tT G + + + Y8 NtT H

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33 CHAPTER 4 RESULTS This chapter presents the results obt ained after treating the ash at the conditions described in Chapter 3. The chapter is divided into five main sections; the first section presents the chemical anal ysis of the non-treat ed ash as well as the results of X-ray analysis of the nontreated ash sample. The second section presents the results of appl ying hydrothermal treatment to the ash; the results included are focusing on the obtained percen tages of each produced zeolite type from X-ray diffraction pattern analysis as well as the percentages estimated from both X-ray patterns and cation exchange capacity property. The third section presents the results of introducing the fusi on step as a pretreatment step for the ash prior to hydrothermal step. The fourth section focuses on zeolite A production from the treated ash and section five will show the results of the experimental design analysis for zeolit e A formation using the method described in chapter 3. 4.1 Ash Composition The results of chemical analysis fo r the combined ash sample, which was assembled as described in chapter 3, is sh own in Table 4.1. The results indicate that silica is the major element present in the ash. Alumina, which is as important

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34 as silica for zeolite synthesis, is pres ent in lower amounts than required for the synthesis of certain zeolite types, such as zeolite A. The molar SIO2/Al2O3 ratio was found to be 13.9. This ratio is consider ed higher than that r equired for zeolite A formation (< 3); however, this ratio is more suitable for the formation of other zeolite types such as X and P. Calcium wa s found to be present in relatively high amounts which can affect zeolite synthes is as calcium competes with sodium cation to occupy the active sites of t he formed zeolite (Barrer, 1982). This can change the reaction products toward forming different zeolite structures. Cations such as K, Mg, Mn and Cu which also co mpete for the active site of zeolite are present in low amounts, and are expecte d to have minimal effect on zeolite formation process. Table 4.1 Chemical composition of ash shown for major and minor elements. In general the ash was found to be cons ists of non-homogenous particles of irregular shapes. A considerable portion of the ash particles were identified as glass shards coming from materials used manufacturing brown, white and green Elemental Oxide Weight % as Oxide Molar % Al2O3 7.86 0.08 SiO2 67.20 1.115 CaO 12.51 0.22 Fe2O3 6.47 0.04 MgO 1.01 0.03 Na2O 5.43 0.09 K2O 0.61 0.0065 MnO 0.05 0.0007 CuO 0.08 0.001 TiO2 6.72 0.08 ZnO 0.49 0.006 PbO 2.46 0.0201 Loss on ignition = 10.7 %

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35 bottles. Other portions were identified as porcelain shards which usually come from common used chinaware. The diffe rent ash portions were chemically analyzed, separately, to det ermine the sources of silica and alumina in the ash (Appendix C). In general, the silica and alum ina sources are mostly the glass and chinaware shards that did not transform during the incineration process. Calcium source is expected to be coming from t he lime added during incineration to buffer the fly ash portion. Figure 4.1 shows the results of X-ray analysis for the combined nontreated ash sample. As shown in Figure 4.1, calcite and quartz are the major crystalline phases present in the ash. The hump noticed in the X-ray pattern indicates the presence of amorphous mate rials, which are likely to be the glass portion which is abundant in the ash as was noticed in the physical examination of the ash. Position [2Theta] 10 20 30 40 50 Counts 0 100 200 QACa QCaQQ QCa Q Figure 4.1 X-ray diffraction patterns for non treated ash sample. Q: Quartz, Ca: Calcite.

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36 4.2 Hydrothermal Treatment The ash was treated hy drothermally at 100 oC under alkaline conditions with sodium hydroxide, NaOH, concentrati ons of 1.5N and 2.5N for time periods of 6, 24 and 72 ho urs. Hydrothermal treatment wa s applied to the ash without adjusting silica/ alumina rati o, 13.9, and after adjusting silica/alumina ratio, 2.5. Silica/alumina ratio was adjusted by adding sodium aluminates as described in chapter 3. The pH values of the solution were in t he range of 11.8 to 11.92 for ash treated with 1.5N sodium hydroxide, while the pH was in the rage of 11.9 12.3 for ash treated at 2.5N sodium hydroxide. The cation exchange capacity values, the percentages of produced zeolites calculated from the X-ray diffraction pattern and the estimated zeolite perc entages as determined from combined Xray pattern and cation exchange capacity property are summarized in Tables 4.24.5. Treating the ash hydrothermally at 1. 5N with silica/alumina ratio of 13.9 and 2.5 are summarized in Tables 4.2 and 4.3, respectively. Tables 4.4 and 4.5 show the results of treating the as h hydrothermally at 2.5N for silica /alumina ratio of 13.9 and 2.5, respectively. Figures 4.2 and 4.3 show the x-ray diffraction pattern obtained for the treated ash samples at 1.5N for silica/al umina ratio 13.9 and 2.5, respectively. Figures 4.4 and 4.5 present the x-ray diffraction pattern for the treated ash samples at 2.5N for silica/alumina ratio 13.9 and 2.5, respectively. As shown in Table 4.2 when the ash is tr eated hydrothermally at 1.5N with 13.9 silica/alumina ratio for a period of 6 to 72 hours, one z eolite phase was formed and identified as un-named zeolite (Na8Al6Si6O24(NO2)2.3H2O).

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Table 4.2 Hydrothermal treat ment for the ash at 100 oC with sodium hydroxide concentration of 1.5N, silica/alumina ratio is 13.9. NaOH Concentration, N 1.5 N Silica/alumina ratio 13.9 Time, hours 6 24 72 Compound X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) Quartz, SiO2 64.7 48.4 21.1 Calcite, CaCO3 31.96 39.4 18.67 Un-named zeolite Na8Al6Si6O24(NO2)2.3H2O 3.3 3.57 27.5 12.2 4. 39 33.8 60.78 8.78 67.6 Total 100 3.57 27.5 100 4.39 33.8 100 8.78 67.6 Table 4.3 Hydrothermal treat ment for the ash at 100 oC with sodium hydroxide concentration of 1.5N, silica/alumina ratio is 2.5. NaOH Concentration, N 1.5 N Silica/alumina ratio 2.5 Time, hours 6 24 72 Compound X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) Quartz, SiO2 67.61 69.98 45.03 Calcite, CaCO3 9.64 4.91 5.26 Katoite Ca2.93Al1.97Si.64O2.56(OH)9.44 12.38 8.52 12.81 Zeolite P1 Na6Al6Si10O32(H2O)12 2.89 8.95 41.0 6.09 8.84 40.5 Un-named zeolite Na8Al6Si6O24(NO2)2.3H2O 13.69 4.43 34.1 30.82 4.22 32.5 Un-named zeolite Na8Al6Si6O24(NO2)2 10.37 7.93 63.9 Total 100 7.93 63.9 100 13.38 75.1 100 13.06 73.0 37

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Table 4.4 Hydrothermal treatment for ash at 100 oC and sodium hydroxide concentration as 2.5N, silica/alumina ratio is 13.9. NaOH Concentration, N 2.5 N Silica/alumina ratio is 13.9 Time, hours 6 24 72 Compound XRay % Zeolite % (estimated) CEC (meq/100g) XRay % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) Quartz, SIO2 66.4 71.9265.79 Calcite, CaCO3 26.2814.747.48 Un-named zeolite Na8Al6Si6O24(NO2)2.3H2O 7.33 6.81 52.4 13.347. 65 58.9 26.73 9.68 74.5 Total 100 6.81 52.4 100 7.65 58.9 100 9.68 74.5 Table 4.5 Hydrothermal treatment for ash at 100 oC and sodium hydroxide concentration as 2.5N, silica/alumina ratio is 2.5. NaOH Concentration, N 2.5 N Silica/alumina ratio is 2.5 Time, hours 6 24 72 Compound XRay % Zeolite % (estimated) CEC (meq/100 g) X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) Quartz, SIO2 53.3360.36 44.31 Calcite, CaCO3 7.84 7.3 6.02 Katoite Ca2.93Al197Si.64O256(OH)9.44 16.9410.5 11.38 Un-named zeolite Na8Al6Si6O24(NO2)2.3H2O 21.898.47 65.2 21.79 8. 5 65.4 38.29 9.68 74.5 Total 100 8.47 65.2 100 8.5 65.4 100 9.68 74.5 38

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39 The estimated percentages were found to be in the range of 3.578.78%. The CEC values were in the range of 27.5-67.6 meq/100g and non-zeolitic phases detected were quartz and calcite. The exact amounts of non zeolitic phases could not be calculated exactly since X-ray analysis ignored amorphous content, and did not provide the right propor tions of the ash due to the complexity of the studied, this complexi ty resulted due to the variat ion in grain sizes and the morphology of the ash. In addition, t he second method used to estimate the percentages in the ash is va lid only to estimate zeolit ic phases and cannot be used to estimate non zeolitic phases. However, the percentages obtained from X-ray analysis for non zeolitic phases still can be used for comparing the cases studied. When silica /alumina ratio was adjusted to 2.5, a new zeolite phase was formed in addition to un-named zeolite and was identified as zeolite P1 (Na6Al6Si10O32 (H2O)12) as shown in Table 4.3. The total estimated zeolitic phases were in the range of 7.9313.06 % with CEC values in the range of 63.975.1. The non zeolitic phases present were quartz, calcite and a new phase identified as Katoite (Ca2.93Al1.97Si.64O2.56 (OH)9.44). As the normality of reacting solution increased from 1.5N to 2.5N no significant change was observed in zeolit e phases formation, except for zeolite P1 which did not form as sh own in Tables 4.4 and 4.5. Non zeolitic phases were also quartz, calcite and katoite.

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40 Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 3600 R R R Q Q Q Uz Uz Ca Ca R Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 3600 6400 Uz Uz Uz Uz Q Q Q Ca R R R Figure 4.2 X-ray diffraction pattern obtained for the ash treated at 1.5N for 6, 24 and 72 hours with silica/alumin a ratio 13.9. Uz: Unnamed zeolite, Q: Quartz, R: Rutile, Ca: Calcite. Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 R R R Ca Ca Q Q Q Uz Uz Ca Uz 6 hours 24 hours 72 hours

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41 Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 Uz Uz Uz P1 P1 Ca Ka Ka Ka Q Q R R R R Q Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 1600 Ka Ka Ka Ca Ca Uz Uz Q Q R R R Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 Q Q R R R R Ka Ka Ka P1 P1 Uz Uz Uz Uz Uz Ca Ca Figure 4.3 X-ray diffraction pattern obtained fo r the ash treated at 1.5N for 6, 24 and 72 hours with silica/alumina ratio 2.5. P1: Zeolite P1, Uz: Unnamed zeolite, Q: Quartz, R: Rutile, Ca: Calcite, Ka: Katoite. 6 hours 24 hours 72 hours

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42 Position [2Theta] 10 20 30 40 50 Counts 0 2500 10000 Uz Q Q Ca Ca R R R Uz Uz Position [2Theta] 10 20 30 40 50 Counts 0 1000 2000 Uz Uz Uz Uz Ca Ca Q Q R R R R Q Ca Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 3600 R R R R Q Q Ca Ca Ca Uz Uz Uz Uz Figure 4.4 X-ray diffraction pattern obtained fo r the ash treated at 2.5N for 6, 24 and 72 hours with silica/alumina ratio 13.9. Uz: Unnamed zeolite, Q: Quartz, R: Rutile, Ca: Calcite. 6 hours 24 hours 72 hours

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43 Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 1600 Ka Ca Ca Ka R R R R Q Q Q Uz Uz Uz Uz Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 3600 R R R Q Q Ka Ka Uz Uz Uz Ca Ca Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 3600 Ca Ka Ka Ca Q Q R R R R Uz Uz Uz Uz Q Figure 4.5 X-ray diffraction pattern obtained fo r the ash treated at 2.5N for 6, 24 and 72 hours with silica/alumina ratio 2.5. Uz: Unnamed zeolite, Q: Quartz, R: Rutile, Ca: Calcite, Ka: Katoite. 6 hours 24 hours 72 hours

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44 4.3 Fusion Prior to Hy drothermal Treatment In order to activate or dissolve the ash particles that iclude quartz, porcelain and glass, and make them av ailable for reaction during zeolite formation stages, the ash was su bjected to fusion at 5500C prior to hydrothermal reaction as described in Chapter 3. Three different levels of hydroxide concentrations were used in the fusion step were 1.5N, 2.5N and 3.5N sodium hydroxide. Hydrothermal reaction was per formed at two different temperatures, 600C and 100 0C. Reaction periods were as 6, 24 and 72 hours. The results for each case used are presented below. The pH values were 11.8 11.92 for 1.5N, 11.9 -12.3 for 2.5N and 12.2-12.5 for 3.5N. Table 4.6 shows different phases formed as a result of subjecting the ash to fusion at 550 oC for 3 hours using sodium hydrox ide concentration of 1.5, 2.5 and 3.5 normality, respectively. As show n in Table 4.6, t he fusion step did actually result in production of phases t hat could be of import ant in directing the reaction toward the formation of different zeolite phases. Fusing the ash at 1.5 N produced a sodium aluminum silicate phase that could work as precursor to zeolite formation. Fusion of the ash at 2.5 and 3.5 produced sodium silicate phase which is an important pr ecursor to zeolite formati on. An additional phase was formed at 3.5N that was identified to be unnamed zeolit e. Quartz phase was not detected when ash was fused at 2.5N and 3.5N and calcite phase was detected regardless of what fusion condition is used.

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45 Table 4.6 Phases produced as a result of subjecting the ash to fusion at 550 oC for 3 hours. 4.3.1 Hydrothermal treatment for fused ash at 1.5N Tables 4.7 and 4.8 show the CEC values, percentages of different treated ash fractions and estimated percentages of zeolite produced during hydrothermal reaction at 100 0C for fused ash at 1.5N. The X-Ray diffraction patterns of different formed phases in this case are shown in Figures 4.6 and 4.7. As shown in Table 4.7 when ash was fused and subjec ted to hydrothermal reaction at silica to alumina ratio of 13.9, zeolite X (6.4 %), P1 (13.4%) and unnamed zeolite (9.36 %) were formed at 72 hours. The CEC of the ash dramatically increased from 17.0 meq/100g for non treated ash up to 164 meq/100g. Fusion Conditions Fusion at 550 oC for 3 hours Hydroxide concentration N 1.5N 2.5N 3.5N Phases formed % % % SiO2 31.6 4.6 CaCO3 2.1 CaCO3 +Sodium silicate (Na2SiO3) 8.0 15.14 Sodium alumina silicate (NaAlSiO4) 18.3 Sodium alumina silicate hydrate, Unnamed zeolite (Na2Al2Si1.68.O7.76.1.73H2O) 10.9 Sodium carbonate hydrate (Na2CO3.H2O) 48 34.5 69.3 Sodium carbonate (Na2CO3 ) 22.9 Sodium nitrate (NaNO2) 34.5

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Table 4.7 Fused ash with 1.5N follow ed by hydrothermal treatment at 100 oC, silica/alumina ratio is 13.9. NaOH Concentration Normality N 1.5 N Silica/alumina ratio is 13.9 Time, hours 6 24 72 Compound X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) Quartz, SIO2 47.7 40.49 35.14 Calcite, CaCO3 19.8 31.28 28.39 Unnamed zeolite (Na1.66AlSiO4.33) 32.5 10.1 103 28.23 10.7 109.6 Zeolite X (Na2Al2Si2.5O9.6.2H2O) 4.63 6.4 30.4 Zeolite P1 Na6Al6Si10O32(H2O)12 10.27 13.44 61.6 Un-named zeolite Na8Al6Si6O24(NO2)2.3H2O 15.81 9.36 72 Total 100 10.1 103 100 10.7 109.6 100 17.2 164 Table 4.8 Fused ash with 1.5N follow ed by hydrothermal treatment at 100 oC, silica/alumina ratio is 2.5. NaOH Concentration Normality N 1.5 N Silica/alumina ratio is 2.5 Time, hours 6 24 72 Compound X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) Quartz, SIO2 27.65 31.45 29.74 Calcite, CaCO3 19.13 19.41 26.33 Gibbsite, Al(OH)3 23.58 20.5 9.59 Bayerite, Al(OH)3 16.69 14.82 Un-named zeolite Na8Al6Si6O24(NO2)2.3H2O 11.28 10.11 77.78 34.32 17.08 131.4 Un-named zeolite Na8Al6Si6O24(NO2)2 13.7 14.5 116.87 Zeolite A (Na96Al96Si96O384.216H20) 1.7 1.98 10.85 Total 100 12.09 88.63 100 14.5 116.87 100 17.08 131.4 46

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47 Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 3600 SAS Ca Ca SCH SCH SCH Q R R R SCH SAS Q Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 3600 Ca Uz Uz Uz R R R R Ca Q Q Figure 4.6 X-ray diffraction pattern obtained for fused ash at 550 0C at 1.5N and hydrothermally treated at 100 0C for 6, 24 and 72 hours, resp ectively, with silica/alumina ratio of 13.9. SAS: Sodium alumina silicat e, SCH: Sodium Carb onates Hydrate, Uz: Unnamed zeolite, Q: Quartz, R: Rutile, Ca: Calcite. 6 hours Fused ash

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48 Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 Uz Uz Ca Ca Ca Ca Q Ca R R R R Q R Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 1600 Uz Uz X X X P1 P1 X P1 Ca Ca R R R R Q Q Ca R Figure 4.6 (Continued) X: Zeolite X, Uz: Unnamed Zeolite, Q: Quartz, R: Rutile, Ca: Calcite, P1: Zeolite P1. 72 hours 24 hours

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49 Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 1600 Ca Ca Q Q A A A R R R Ba Gi Ba Uz Uz Uz Ca R Gi Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 1600 Uz Uz Uz Q Q Ba Ba Ca Ca Ca R R R Ba Gi Bi Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 1600 Gi Gi Q R Q R R R Uz Uz Uz Uz Ca Ca Ca Figure 4.7 X-ray diffraction pattern obtained for fused ash at 1.5N that was treated hydrothermally at 100 0C for 6, 24 and 72 hours with silic a/alumina ratio of 2.5. Uz: Unnamed zeolite, Q: Quartz, R: Rutile, Ca : Calcite, Gi: Gibbsite, Ba: Bayerite, A: Zeolite A. 24 hours 6 hours 72 hours

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50 Quartz and calcite were still the main no n zeolitic phases present and they contribute to the larger fractions in the as h. However, they are present in smaller quantities than those obtained from treating the ash hydrothermally without fusion. When silica to alumina ratio wa s reduced from 13.9 down to 2.5 for the fused sample and then hydrothermally treated at 100C, different zeolite phases start to appear including the formation of zeolite A as shown in Table 4.8 and Figure 4.7. Zeolite A appear ed in small amounts (1.98 %) at 6 hours reaction time and disappears as the reaction time was prolonged. Hydrated and dehydrated forms of unnamed zeolite were the only ot her zeolite phase that formed in this case. The CEC value ranged between 88.63131.4 meq/100g. Also, it was noticed that as silica/ alum ina ratio was adjusted a new non zeolitic phases formed that was identified as gibbsite and bayerite. These phases have chemical compositions as aluminum hy droxide. Their forma tion indicates the presence of excess aluminum in the r eaction system which precipitated during zeolite formation stage. To study the effect of reaction te mperature on zeolite formation, the reaction temperature was reduced from 100oC to 60oC for fused ash at 1.5N. Tables 4.9 and 4.10 and Figur es 4.8 and 4.9 show zeolite phases that formed as the temperature was reduced to normality of 1.5N and at silica/alumina ratios of 13.9 and 2.5, respectively. As shown in Table 4.9, un-named zeolite was the only zeolite phase present and its percentages are around 11.75 %, the CEC values were around 90 meq/100g. Zeolite cont ent and CEC values were decreased when the temperature was reduced.

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Table 4.9 Fused ash with 1.5N followed by hydrothermal treatment at 60 oC, silica/alumina ratio is 13.9. NaOH Concentration Normality N 1.5 N Silica/alumina ratio is 13.9 Time, hours 6 24 72 Compound X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) XRay % Zeolite % (estimated) CEC (meq/100g) Quartz, SIO2 32.41 43.44 25.58Calcite, CaCO3 46.33 38.33 50.02Un-named zeolite Na8Al6Si6O24(NO2)2.3H2O 21.26 11.28 86.8 18.23 11. 75 90.4 24.4111.96 92 Total 100 11.28 86.8 100 11.75 90.4 100 11.96 92 Table 4.10 Fused ash with 1.5N followe d by hydrothermal treatment at 60 oC, silica/alumina ratio is 2.5. NaOH Concentration Normality N 1.5 N Silica/alumina ratio is 2.5 Time, hours 6 24 72 Compound X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) Quartz, SIO2 24.6 25.73 15.8 Calcite, CaCO3 19.1 18.94 26.55 Gibbsite Al(OH)3 12.77 16.1 23.88 Bayerite Al(OH)3 22.87 16.19 23.1 Un-named zeolite (Na2Al2Si1.68.O7.76.1.73H2O) 23.4 14.26 102 17.08 11.8 84.4 5.53 8.0 57 Zeolite A (Na96Al96Si96O384.216H20) 3 3.49 19.1 5.9 7.86 43 5.21 3.91 21.39 Total 100 17.75 121.1 100 19.66 127.4 100 11.91 78.39 51

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52 Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 1600 Ca Ca R R R R Q Q Uz Uz Uz Uz Ca Ca Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 Uz Uz Uz Uz Ca Ca Ca Ca Ca R R R Q Q R Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 3600 Uz Uz R R R R Q Q Ca Ca Ca Ca Figure 4.8 X-ray diffraction pattern obtained for fused ash at 1.5N that was treated hydrothermally at 60 0C for 6, 24 and 72 hours with silica/alumina ratio of 13.9. Uz: Unnamed zeolite, Q: Quartz, R: Rutile, Ca: Calcite. 24 hours 72 hours 6 hours

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53 Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 1600 Gi Gi Gi Uz Uz Ca Ca A A A A R R R Q Q R Ca Ba Ba Ba Ba Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 1600 R R R R Q Q Ca Ca Ca Ca Gi Gi Ba Ba Gi Ba A A A A Uz Uz Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 1600 R R R Ca Ca Ca Gi Gi Gi Ba Ba Ba Ba A A A A A Uz Uz Uz Figure 4.9 X-ray diffraction pattern obtained for fused ash at 1.5N that was treated hydrothermally at 60 0C for 6, 24 and 72 hours with silica/alumina ratio of 2.5. Uz: Unnamed zeolite, Q: Quartz, R: Rutile, Ca: Calcite, A: Zeolite A, Gi: Gibbsite, B: Bayerite. 6 hours 24 hours 72 hours

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54 For a silica/ alumina ratio of 2.5, zeolite A was formed with percentages of 3.49 % for 6 and 72 hours and 7.8 % for 24 hours. Unnamed zeolite phase was formed in this case in the range of 11. 91% 17.75% and the CEC values were between 78.39127.4 meq/100g. Non zeo litic phases of gibbsite and bayerite were also observed to fo rm in this case too. 4.3.2 Hydrothermal treatment for fused ash at 2.5N Conditions used for fused ash at 1. 5N were repeated for fused ash at 2.5N. It is expected that increasing the hydroxide concentration may increase the activity of the silica and alumina in t he ash which will result in increasing the percentages of formed zeolites. Tables 4.11 and 4.12 and Figures 4.10 and 4.11 show the produced zeolite p hases that formed at 100 0C for 2.5N fused ash with silica/alumina ratios of 13. 9 and 2.5, respectively. As shown in Table 4.11, unnamed zeolite was the only ph ase that formed for 2.5N fused ash. Zeolite P1 was formed in this case while Zeolite X di d not form as it did for 1.5N fused ash sample. Unnamed zeolite phase was present in percentages ranged between 20.3 41.68 %. It seems that zeolit e phase percentages have almost doubled as hydroxide concentration was increased from 1.5N to 2.5N. The CEC values were in the range of 168.4-191 meq/ 100g. The CEC values also significantly increased as hydroxide solution was incr eased from 1.5N to 2.5N. When silica to alumina ratio was reduc ed from 13.9 to 2.5 for 2.5N fused ash at 100 0C, zeolite A phase was formed as it did for 1.5N fused ash with reduced silica / alumina ratios. It seems t hat zeolite A forms only when silica to alumina ratio is reduced and samp les are subjected to fusion.

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Table 4.11 Fused ash with 2.5N followe d by hydrothermal treatment at 100 oC, silica/alumina ratio is 13.9. NaOH Concentration Normality N 2.5 N Silica/alumina ratio is 13.9 Time, hours 6 24 72 Compound X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) Quartz, SiO2 46.96 36.41 40.36 Calcite, CaCO3 16.63 13.42 22.11 Unnamed zeolite (Na2Al2Si1.68.O7.76.1.73H2O) 12.8 8.16 58.4 41.94 19.46 139.2 Unnamed zeolite (Na6Al4Si4O17) 23.62 12.14 115.5 8.23 3.07 29.2 Zeolite P1 Na6Al6Si10O32(H2O)12 37.53 41.68 191.0 Total 100 20.3 173.9 100 22.53 168.4 100 41.68 191.0 Table 4.12 Fused ash with 2.5N followe d by hydrothermal treatment at 100 oC, silica/alumina ratio is 2.5. NaOH Concentration Normality N 2.5 N Silica/alumina ratio is 2.5 Time, hours 6 24 72 Compound X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) Quartz, SiO2 21.99 20.51 18.17 Calcite, CaCO3 44.21 44.49 35.26 Zeolite Zk-14 (Na3.68Al36Si8.4O24.H2O) 19.24 8.88 34.1 Unnamed zeolite Na8Al6Si6O24(NO2)2 26.71 12.54 101.0 Zeolite A (Na96Al96Si96O384.216H2o) 14.6 28.5 155.9 8.3 14.26 78 3.28 11.08 60.6 Sodalite Na8Al6Si6O24(NO2) (CO3).5 43.29 16.49 135.4 Total 100 37.38 190 100 26.8 179 100 27.57 196 55

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56 Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 SAS SS SAS SC Ca SS SN SC SC SS SS SC Ca SN SCH SCH Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 1600 R R R Ca Ca Ca Q Q SAS SAS SA SA R Figure 4.10 X-ray diffraction pattern obtained for fused ash at 550 0C at 2.5N and hydrothermally treated at 100 0C for 6, 24 and 72 hours, resp ectively, with silica/alumina ratio of 13.9. SAS and SA: Sodium alumina s ilicate, SCH: Sodium Carbonates Hydrate, SC: Sodium carbonate, Uz: Unnamed zeolite, Q: Quartz, R: Rutile, Ca: Calcite. 6 hours Fused ash

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57 Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 R R R R Ca Q Q SA SAS SAS SA Ca Q Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 3600 Ca Ca Q Q R R R P1 P1 P1 P1 P1 R Figure 4.10 (Continued) SAS and SA: Sodium Alumina Silicate, Q: Quartz, R: Rutile, Ca: Calcite, P1: Zeolite P1. 72 hours 24 hours

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58 Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 Q Q R R A A A A A Ca Ca Ca Zk Zk A Q A Zk R A Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 Uz Uz Uz A A A A R R R R Q Q Ca Ca Ca A Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 1600 R R R R Ca Ca Ca Ca A A A A Q Zk Zk So So So So A Figure 4.11 X-ray diffraction pattern obtained for fused ash treated hydrothermally at 2.5N at 100 0C for 6, 24 and 72 hours with silica/alumina ratio of 2.5. Uz: Unnamed Zeolite,Q: Quartz, R: Rutile, Ca: Ca lcite, A: zeolite A, Zk: Zeoltie Zk-14. 6 hours 24 hours 72 hours

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59 In this case another zeolite phase appeared and was identified as Zk-14 zeolite. the unnamed zeolite phase appeared only at 24 hour and a new phase identified as sodalite was formed at 72 hours. The to tal zeolitic phases formed were in the range of 26.8-37.38%. The CEC values were between 179 meq/100g and 196 meq/100g. It appears that no significant changes occurred for both zeolite percentages and CEC values as silica to alumina ratio was reduced for 2.5N fused ash at 1000C. Also, it was observed that there is no excess aluminum hydroxide precipitate (gibbs ite and bayerite) which indi cates that when hydroxide concentration is increased by fusing the as h at 2.5N instead of 1.5N, more silica dissolute and becomes available for reaction with alumina. In order to determine the effect of reducing the reaction temperature on the formation of different zeolite phases, reaction temperature was reduced from 1000C to 600C for fused ash at 2.5N. Tables 4.12 and 4.13 and Fi gures 4.12 and 4.13 show the produced zeo lite phases formed at 600C for 2.5N fused ash with silica/alumina ratios of 13.9 and 2.5, respectively. Unnamed zeolite was the major zeolite phase that formed for fused ash at 2.5N that was treated at 600C with silica/alumina ratio of 13.9 as shown in Table 4.12. Zeolite phase percentages were around 20% and CEC val ues were in the range of 80 meq/100g to 175.1 meq/100g. In general, z eolites percentages and CEC values were lower for 2.5N fused samples at 60 oC than that obtained for 2.5N fused samples at 100 oC for silica/alumina ratio of 13.9.

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Table 4.13 Fused ash with 2.5N followed by hydrothermal treatment at 60 oC, silica/alumina ratio is 13.9. NaOH Concentration Normality N 2.5 N Silica/alumina ratio is 13.9 Time, hours 6 24 72 Compound X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) Quartz, SiO2 47.08 69.11 40.38 Calcite, CaCO3 15.7 15.35 16.91 Un-named zeolite Na8Al6Si6O24(NO2)2.3H2O 20.25 12.9 92.3 15.54 10.4 80 24.3 19.61 150 Unnamed zeolite (Na6Al4Si4O17) 16.97 8.7 82.8 Total 100 21.6 175.1 100 10.4 80 100 19.61 150 Table 4.14 Fused ash with 2.5N followed by hydrothermal treatment at 60 oC, silica/alumina ratio is 2.5. NaOH Concentration Normality N 2.5 N Silica/alumina ratio is 2.5 Time, hours 6 24 72 Compound X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) Quartz, SiO2 27.19 29.1 22.05 Calcite, CaCO3 20.85 40.28 48.12 Zeolite Zk-14 (Na3.68Al3.6Si8.4O24.H2O) 12.61 6.53 25.1 11.95 6.19 23.79 Unnamed zeolite Na8Al6Si6O24(NO2)2 39 12.11 97.6 Zeolite A (Na96Al96Si96O384.216H20) 13 20.6 112.7 18 38.8 212.3 17.87 28.3 154.8 Total 100 32.71 210.3 100 45.33 237.4 100 34.49 178.59 60

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61 Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 1600 SAS Q Q Q UZ Uz UZ R R R R Ca Ca SAS Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 3600 R R R R Ca Ca Ca Uz Uz Q Q Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 1600 Uz UZ R R R R Ca Ca Ca Q Q Figure 4.12 X-ray diffraction pattern obtained for fused ash treated hydrothermally at 2.5N at 60 0C for 6, 24 and 72 hours with silica/alumina ratio of 13.9. Uz: Unnamed zeolite, Q: Quartz, R: Rutile, Ca: Calcite. 72hours 24 hours 6 hours

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62 Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 Q Q Zk Zk Ca Ca Ca R R R A A A A A A A Ca Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 1600 Uz Uz UZ Uz R R R R Q Q A A A A Ca Ca A A Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 A A A A A A Zk Zk R R R Ca Ca Ca Ca Q A Q R A Figure 4.13 X-ray diffraction pattern obtained for fused ash treated hydrothermally at 2.5N at 60 0C for 6, 24 and 72 hours with silica/alumina ratio of 2.5. Uz: Unnamed zeolite, Q: Quartz, R: Rutile, Ca: Calcite, A: Zeolite A, Zk: Zeolite Zk-14. 72hours 24 hours 6 hours

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63 As silica/alumina was reduced to 2.5 for fused ash at 2.5N and treated at 60 oC, zeolites A, Zk-14 and unnamed zeolite were fo rmed as they did when 2.5N fused ash samples were treated at100oC. Zeolite phases percentages were in the range of 32.71% to 45.33% and t he CEC values were in the range of 178.59 meq/100g to 237.4 meq/ 100g. Both zeolite perc entages and CEC values showed an increase when reaction te mperature was reduced from 100 oC to 60oC for silica/alumina ratio of 2.5. In addition, it was noticed that both zeolite percentages and CEC values significantly increased as silica/alumina ratio was reduced. 4.3.3 Hydrothermal treatment for fused ash at 3.5N To study the effect of increasi ng sodium hydroxide concentration on zeolite formation, the ash was fused at 3.5N using the same conditions used for fused ash at 1.5N and 2.5N. Tables 4.15 and 4.16 and Figures 4.14 and 4.15 show the zeolite phases pr oduced that formed at 100 0C for 3.5N fused ash with silica/alumina ratios of 13.9 and 2.5, res pectively. As shown in Table 4.15, the unnamed zeolite was formed as it did in the previous st udied cases and a new phase formed that was identified as zeo lite P1. Total percentages of zeolitic phases were in the range of 18.19% to 37.91 and the CEC values were in the range of 140 meq/100g to 167 meq/100g.

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Table 4.15 Fused ash with 3.5N followed by hydrothermal treatment at 100 oC, silica/alumina ratio is 13.9. NaOH Concentration Normality N 3.5 N Silica/alumina ratio is 13.9 Time, hours 6 24 72 Compound X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) Quartz, SiO2 29.2 33.8 28.2 Calcite, CaCO3 31 30.7 24.5 Unnamed zeolite Na8Al6Si6O24(NO2)2.3H2O 39.9 18.19 140 20.2 11.16 85.9 19.5 8.10 62.3 Zeolite P (Na1.4Al2Si3.9O115.H2O) 15.3 21.9 76.9 27.8 29.81 104.7 Total 100 18.19 140 100 33.06 162.8 100 37.91 167 Table 4.16 Fused ash with 3.5N followed by hydrothermal treatment at 100 oC, silica/alumina ratio is 2.5. NaOH Concentration Normality N 3.5 N Silica/alumina ratio is 2.5 Time, hours 6 24 72 Compound X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) Quartz, SiO2 11.14 6.12 16.49 Calcite, CaCO3 41.4 40.86 30.28 Sodalite Na8Al6Si6O24(NO2) (CO3).5 44.9 8.95 74.13 53.24 17.21 141.3 Unnamed zeolite Na8Al6Si6O24(NO2)2 35.4 9.2 74.13 Zeolite A (Na96Al96Si96O384.216H20) 11.7 18 98.5 8.1 12.65 69.2 Total 100 27.2 172.63 100 21.6 143.33 100 17.21 141.3 64

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65 Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 R R R R Uz Uz Q Uz SS SS Ca SS SS SS Ca SCH SCH SCH SCH Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 3600 6400 Q R R Q Uz Uz Uz Ca Ca R R Figure 4.14 X-ray diffraction pattern obtained for 3.5N fused ash at 500 oC treated hydrothermally treated fused ash at 100 oC for 6, 24 and 72 hours, respectively, with silica/alumina ratio of 13.9. Uz : Unnamed zeolite, Q: Quartz R: Rutile, Ca: Calcite, SS: Sodium silicate, SCH: Sodium Carbonate Hydrate. 6 hours Fused ash

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66 Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 3600 R R R Ca Ca Q Q Uz Uz Uz P P P P Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 R R R R Uz Uz P P P P P Ca Q Ca Ca Figure 4.14 (Continued) Uz: Unnamed Zeolite, Q: Quartz, R: Rutile, Ca: Calcite, P: Zeolite P. 72hours 24 hours

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67 Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 Q R R R Ca Ca A A A A Q Uz Uz Uz Ca Uz Ca Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 So So So A A A A Ca Ca Ca R R R A A So Q Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 3600 Q Q Ca Ca Ca R R R R So So So So Figure 4.15 X-ray diffraction pattern obtained for 3.5N fused ash hydrothermally treated fused ash at 100 oC for 6, 24 and 72 hours with silica/alumina ratio of 2.5. Uz: Unnamed zeolite, Q: Quartz, R: Rutile, Ca: Calcite, So: Sodalite, A: Zeolite A. 24 hours 72hours 6 hours

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68 As the silica /alumina ratio was reduced, zeolite A was formed as expected in this case as shown in Table 4.16. Other zeolite phases formed beside zeolite A included unnamed zeolite and sodalite. Total zeolite phases were estimated in the range of 17.21% to 27.2% with CEC values between 141.3 meq/100g and 172.67meq/100g. It can be seen that no significant changes occurred in both zeolite percentages and the resulted CEC values as silica/ alumina ratio was changed for fused ash at 3.5N at 100oC. The same was observation was noticed for 1.5N and 2.5N fused ash at 1000C. The effect of reducing r eaction temperature from 1000C to 600C on zeolite formation was studied for fused ash at 3.5 N. Tables 4. 17 and 4.18 and Figures 4.16 and 4.17 present the re sulted zeolite phases t hat were formed when reaction temperature was reduced from 100 0C to 60 0C for 3.5N fused ash and silica/alumina ratios of 13. 9 and 2.5, respectively. As shown in Table 4.17, unnamed zeolite was again the main zeo lite phase to form with percentages around 10.8% and CEC values around 83.6 meq/100g. Both zeolite percentages and CEC values seem to be reduced as reaction temperature was reduced for 3.5N fused ash of silica/alumina ratio of 13.9; the same observation was made for 1.5N and 2.5N fused ash of silica/alumina ration of 13.9.

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Table 4.17 Fused ash with 3.5N followed by hydrothermal treatment at 60 oC, silica/alumina ratio is 13.9. NaOH Concentration Normality N 3.5 N Silica/alumina ratio is 13.9 Time, hours 6 24 72 Compound X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) Quartz, SiO2 72.2 23.2 22.7 Calcite, CaCO3 13.3 42.9 40.6 Unnamed zeolite Na8Al6Si6O24(NO2)2.3H2O 14.5 10.85 83.5 33.8 10.86 83.6 36.8 11.24 86.5 Total 100 10.85 83.5 100 10.86 83.6 100 11.24 86.5 Table 4.18 Fused ash with 3.5N followed by hydrothermal treatment at 60 oC, silica/alumina ratio is 2.5. NaOH Concentration Normality N 3.5 N Silica/alumina ratio is 2.5 Time, hours 6 24 72 Compound X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) X-Ray % Zeolite % (estimated) CEC (meq/100g) Quartz, SIO2 6.3 8.78 4.37 Calcite, CaCO3 36.0 58.25 49.14 Unnamed zeolite Na8Al6Si6O24(NO2)2 50.32 14.17 101 17.63 6.26 50.4 33.24 11.8 95 Zeolite A (Na96Al96Si96O384.216H20) 7.34 8.7 47.6 15.35 31. 88 174.4 13.24 27.5 150.4 Total 100 22.87 148.6 100 38.14 224.8 100 39.3 245.4 69

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70 Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 3600 6400 Q Q Uz Uz Uz Ca Ca Ca R R R R Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 1600 Uz Uz Uz Uz R R R R Ca Ca Ca Q Q Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 1600 Ca Ca Ca Q Q Q R R R Uz Uz Uz R R Figure 4.16 X-ray diffraction pattern obtained for 3.5N fused ash hydrothermally treated fused ash at 60 oC for 6, 24 and 72 hours with silica/alumina ratio of 13.9. Uz: Unnamed zeolite, Q: Quartz, R: Rutile, Ca: Calcite. 6 hours 24 hours 72 hours

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71 Position [2Theta] 10 20 30 40 50 Counts 0 100 400 900 1600 Ca Ca Ca A A A A A A A Ca Uz Uz Uz Uz R R R R Q Q Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 R R R R A A A A A A A Ca Ca Ca Ca A A Uz Uz Uz Q Q A Position [2Theta] 10 20 30 40 50 Counts 0 400 1600 R R R R A A A A A A A Ca Ca Ca Ca A A Uz Uz Uz Q Q A Figure 4.17 X-ray diffraction pattern obtained for 3.5N fused ash hydrothermally treated fused ash at 100 oC for 6, 24 and 72 hours with silica/alumina ratio of 2.5. Uz: Unnamed Zeolite, Q: Quartz, R: Rutile, Ca: Calcite, A: Zeolite A. 6 hours 24 hours 72hours

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72 Finally, as the silica /alumina ratio is reduced to 2.5, zeolite A was formed as well as unnamed zeo lite, as shown in Table 4.18. The total zeolitic phases were estimated to be in the range betwe en 22.87% to 39.3% with CEC values in the range of 148.6 meq/100g to 245.4meq/100g. Again a significant increase in zeolite percentages and CEC values were observed as silica/alumina ratio was reduced to 2.5 for fused ash at 600C. 4.3.4 Summary of the results Fusing the ash samples prior to hy drothermal reaction resulted in producing zeolite precursors such as sodi um alumina silicate and sodium silicate. These precursors are import ant for the nucleation of z eolites X, P and A. In general, for fused samples at all hydroxide concentrations and as the reaction temperature is reduced to 600C with the condition where silica/alumina ratio was 13.9, it was f ound that total zeolites pe rcentages and CEC values either remain the same or are reduced. On the other hand, it was also noticed that as silica/alumina ratio was reduc ed to 2.5 higher zeolite percentages and CEC values were obtained as reac tion temperature is reduced. It was noticed that unnamed zeolite an d zeolite A are the major formed zeolite phases for fused ash. It wa s also noticed that unnamed zeolite (Na8Al6Si6O24(NO2)2.3H2O) was the prevailing zeolit e phase when silica/alumina ratio was 13.9 regardless of any other c onditions used. Meanwhile, zeolite A and unmanned zeolite was found to prevail as sili ca/alumina ratio was reduced to 2.5. Finally, zeolite A formation was obs erved when silica/alumina ratio was reduced to 2.5 for fused ash only and it did not form when si lica/alumina ratio

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73 was reduced to 2.5 but the samples were subjected to hydrothermal reaction without fusion pretreatment. 4.4 Zeolite A Formation The formation of zeolites X, P and A is of interest in the present study due to their commercial importance as adsorbe nts. Since both zeolite X and P did not form abundantly or repeatedly under conditions used in the present study, their formation will not be addressed in the present study. However, zeolite A did form in significant amounts and it s formation was reproducible and positively affected the CEC value of the total produced zeolit ic materials. Therefore, zeolite A formation will be focused on in the following sections. Th is section will focus on zeolite A percentages and c ontribution to the final ca tion exchange capacity of the treated ash as well as the morphology and the physi cal characteristics of zeolite A. Section 4.5 will present the results for m odeling zeolite A formation process. Zeolite A mechanism of formati on will be discussed in the next chapter. Figures 4.18 and 4.19 show the estima ted percentages and CEC values for zeolite A formation, respectively. The fi gures present percentage or CEC values versus fused ash at 1.5N, 2.5N and 3.5N for 60 oC and 100 oC temperatures at 6, 24 and 72 hours curing periods. As show n in Figure 4.18, under all conditions studied, it was found that zeolite A yields was highest for 2.5N fused ash reaction, similar results obt ained by Myake et. al., 2002. It was also found that as the temperature increases, reaction time should be reduced to obtain higher yield of zeolite A.

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74 0 5 10 15 20 25 30 35 40 45 11.522.533.54 sodium hydroxide, fusion Estimated percentages (%) 6 hours at 100 0C 24 hours at 100 oC 72 hours at 100 0C 6 hours at 60 oC 24 hours at 60 0C 72 hours at 60 0C Figure 4.18 Zeolite A percentages that were fo rmed at 1.5N, 2.5N and 3.5N fused ash for hydrothermal treatment at 60 0C and 100 oC for 6, 24 and 72 hours. 0 50 100 150 200 250 11.522.533.54 Sodium hydrodixe,N, fusion CEC (meq/100g) 6 hours at 100 oC 24 hours at 100 oC 72 hours at 100 oC 6 hours at 60 oC 24 hours at 60 oC 72 hours at 60 oC Figure 4.19 CEC values for zeolite A obtained at different treatments of 1.5N, 2.5N and 3.5N fused ash for hydrothermal treatment at 60 0C and 100 oC for 6, 24 and 72 hours.

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75 Figures 4.204.26 present scanning el ectron microscopy, SEM, images for original and treated samples at diffe rent studied condit ions. Figure 4.20 shows a typical image for the ash par ticles with sharp non-homogenous morphology. Figure 4.21A present SEM im age for fused samples at 1.5N where it shows the formation of clusters of al umina silicate with flaky structure. These clusters acted as a precursor to zeo lite A formation. Figure 4.21B and C show SEM images of the formation of zeo lite A and unnamed zeo lite at 6 and 24 hours. At 72 hours, only unnam ed zeolite was formed as shown in figure 4.21D. Zeolite A crystals sizes r anged between 0.4-0.56 m when sample was treated at 1.5N at 100 0C. Figure 4.20 SEM image for original ash sh owing sharp non-homogenous components.

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76 Figure 4.21 Fused ash at 1.5 N at 100 oC. A) Fused ash B) 6 hours showing Unnamed Zeolite C) 24 hours showing Cubic Zeolite A D) 72 hours, Unnamed Zeolite and Gibbsite large crystal. A B C D

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77 Figures 4.22A, B and C s how SEM images for cubic zeolite A as it formed at 1.5N at 60 0C for 6,24 and 72 hours. The crystal sizes for zeolite A ranged between 0.5-0.62 m. Figures 4.23A show SEM image of th e formation of alumina silicate clusters with rose like surface structure for fus ed ash at 2. 5N wh ere Figure 4.23 B, C and D show SEM images for zeolite A formation at 100 0C for 6, 24 and 72 hours. Zeolite A crystal sizes were betwe en 0.7-1.2 m. Figure 4.24A B and C shows SEM images for zeolite A formation at 6,24 and 72 hours for fused ash at 2.5N at 60 0C. Zeolite A crystal sizes were 1.1-1.6 m in this case. Figure 4.25A shows aluminosillicate cl uster formation for the fused sample at 3.5 N that also has a rose like surfac e structure. Figure 4.25B, C and D show zeolite A formation at 6,24 and 72 hours for fused ash at 3.5N at 100 0C. Zeolite A crystal sizes were formed in the r ange between 0.54-0.81 m Figure 4.26A, B and C show zeolite A formation at 6,24 and 72 hours, respectively, for fused ash at 3.5N at 60 0C. Zeolite A crystal sizes were in the range of 0.7 0.9 .m.

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78 Figure 4.22 Fused ash at 1.5N at 60 oC. Zeolite A formation at different crystallization periods. A) 6 hours B) 24 hours and C) 72 hours. B A C

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79 Figure 4.23 Fused ash at 2.5N at 100 oC. A) Fused ash B) 6 hours, Zeolite A and zeolite ZK-14 C) 24 hours, cubic Zeolite A and Unnamed Zeolite D) 72 hours, Zeolite A and Sodalite. A B C D

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80 Figure 4.24 Fused ash at 2.5N at 60 oC. Zeolite A formation at different crystallization periods. A) 6 hours B) 24 hours and C) 72 hours. A B C

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81 Figure 4.25 Fused ash at 3.5N at 100 oC. A) Fused ash B) 6 hours, Zeolite A and Unnamed zeolite C) 24 hours, cubic Zeo lite A D) 72 hours, Sodalite. A B C D

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82 Figure 4.26 Fused ash at 3.5N at 60 oC. Zeolite A formation at different crystallization periods. A) 6 hours B) 24 hours and C) 72 hours. A B C

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83 4.5 Experimental Design Analysis and Modeling of Zeolite A Formation Zeolite A formation was modeled based on 23 experimental design analysis as described in chapter 3. The average of triplicate samples was taken for each studied case (Appendix D). The general formula for zeolite A yields using 23 experimental design analysis and as described in equation 3.3 is as follows: Yi = f( N, T t) Yi = a +bN + cNt + dt + eT + fNT + gTt + hNTt (equation 3.3) Where: Y: is zeolite yield. a: intercept. b,c,d,e,f,g and h: Equation coefficients. N: Sodium hydroxide concentration. t: Time, hours. T: Temperature, oC. The above model was tested by per forming regression analysis using least square method to evaluate the linearity of the model using R2 value and residues. As the above model was evaluated for linearity it was found that the resulted R2 value was low, 0.86, and the residuals were high (Appendix E). Regression analysis performed on the m odel showed good fitness only as sodium hydroxide is rais ed to n power (Appen dix F). This indicates that the synthesis process cannot be linearly modeled. This was confirmed by the relationship shown in Figure 4.18 where it indi cates that as temperatures, times

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84 and hydroxide concentrations is changi ng the relationship appears to become polynomial. Accordingly, to better explai n the interaction between the different conditions used, Yatess algorithm analysis technique was to evaluate equation 3.3 by applying the Yatess algorithm analysis at two separate cycles using different boundaries for sodium hydroxide concentrations. C ycle 1 was performed for 1.5N and 2.5N whereas cycle 2 was performed for 2.5N and 3.5N. Temperature and time higher and lower levels were 100 oC and 60 oC for temperature and 24 and 6 h ours for time. Tables 4.19 and 4.20 show summary for conditions used at each cycle. Coeffi cients of equation 3.1 were determined for each cycle using Yatess algorithm anal ysis to study the effect of different used conditions on zeolite A formation. Table 4.19 Summary for conditions used to perform Yatess algorithm analysis for cycle 1. Level Sodium hydroxide conc entrations(Normality), N Time (hours) T Temperature( 0C) T 1.5 6 60 + 2.5 24 100 Table 4.20 Summary for conditions used to perform Yatess algorithm analysis for cycle 2. Level Sodium hydroxide conc entrations(Normality), N Time (hours) T Temperature( 0C) T 2.5 6 60 + 3.5 24 100

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85 The coefficients for yield equations calculated from Yatess Algorithm (Appendix G) for each cycle are descr ibed here below. The meanings and implications of each case are discussed in details in the next chapter. The Yield equation for 1.5N and 2.5N cycle was found to be as: Ycycle1 = 14.4 + (22.26/2)N + (1.7 1/2)Nt + (0.34/2)t (6 .53/2)T (1.87/2)NT (9.67/2)Tt (6.47/2)NTt (4.2) And the yield equation for 2.5N and 3.5N cycle was found to be as: Ycycle2 = 21.63 (7.75/2)N + (5. 43/2)Nt + (3.45/2)t (6 .63/2)T + (1.7/2)NT (15.22/2)Tt (1/2)NTt (4.3)

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86 CHAPTER 5 DISCUSSION This chapter will discuss the results pr esented in chapter 4. The chapter is divided into three sections. The firs t section will discuss the importance of introducing the fusion step prio r to hydrothermal reaction to produce zeolite. This section will discuss the formation of different zeolite types with the focus on the formation of certain types of zeolite in cluding zeolite A, P and X. The second section will discuss zeolite A formation. Both the theory and the mechanism of formation of zeolite A will be addressed in this section. Finally, section three will discuss the implications of the pr oposed model and its constraints. 5.1 Hydrothermal Versus Fusion Pr ior to Hydrothermal Treatment 5.1.1 The effect of applying hydrothermal treatment alone The hydrothermal treatment was found to be not effective in producing zeolite in significant am ounts and consequently this translated into low CEC values. In general, unnamed zeolite type of sodalite structure ( Na8Al6Si6O24(NO2)2.3H2O) was the major zeolite phase that was formed regardless of conditions be ing used. Zeolite P1 was another zeolite phase that was formed at 24 and 72 hours for treated ash at 1.5N and at 100 0C.

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87 Figures 5.1 5.4 shows the percentages of the zeolites formed and their CEC contribution when ash was treated at 1.5N and 2.5N and at a silica to alumina ratios of 13.9 and 2.5N, respectively. For non adjusted silica /alumina ratio (13.9) and at 1.5N only unnam ed zeolite was formed with maximum CEC value of 67.6 meq/100g obtained after 72 hours reaction time (Figure 5.1). As silica/alumina ratio was adjusted to 2.5, unnamed zeolite prevailed at 6 hours and either partially dissoluted or transforme d into zeolite P1 (Figure 5.2A and B) at 24 and 72 hours. Zeolite P1 was formed in small amounts (~ 9% only) and therefore its contribution to the CE C was low (41 meq/100g). Zeolite P1 formation as silica/alumina ratio was adjus ted indicates that alumina present in the original ash was not high enough to form this type of zeolite. A new nonzeolitic phase was observed to form as silica/alumina ratio was reduced, this phase was identified as katoite (Ca2.93Al1.97Si.64O2.56(OH)9.44 ). The formation of katoite indicated that calcium competes with sodium ion in t he reaction system as it reacted with the excess silica and alumina to form calcium alumina silicate hydroxide. However, as the reacting hydroxid e concentration was increased by increasing the addition of s odium hydroxide from 1.5N to 2.5N, and with adjusting silica to alumina ratio again to 2.5, z eolite P1 did not form at these conditions and only unnamed zeolit e and katoite were formed (F igures 5.3 and 5.4) The reason for such observation could be that at 2.5N more silica was dissolved so silica/alumina ratio becomes higher than that required for zeolite P1 formation. However, it was still in the range to fo rm unnamed zeolite and non zeolite katoite.

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88 6 24 72 unnamed zeolite CEC 0 10 20 30 40 50 60 70 Time ( Hours) unnamed zeolite CEC Figure 5.1 Zeolite yield and CEC valu es produced for applying hydrothermal treatment at 1.5N at 100 0C, at silica/ alumina ratio of 13.9. 6 24 72 unnamed zeolite CEC 0 10 20 30 40 50 60 70 Time ( Hours) A unnamed zeolite CEC 6 24 72 zeolite zeolite P1 CEC 0 10 20 30 40 50 60 70 Time ( Hours) B zeolite zeolite P1 CEC 6 24 72 total zeolite total CEC 0 10 20 30 40 50 60 70 Time ( Hours) C total zeolite total CEC Figure 5.2 Zeolite yield and CEC values produced fo r applying hydrothermal treatment at 1.5N at 100 0C and at silica/ alumina ratio of 2.5. A) U nnamed zeolite. B) Zeolite P1. C) Total zeolites.

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89 6 24 72 unnamed zeolite CEC 0 10 20 30 40 50 60 70 Time ( Hours) unnamed zeolite CEC Figure 5.3 Zeolite yield and CEC values produced for applying hydrothermal treatment at 2.5N at 100 0C, at silica/ alumina ratio of 13.9. 6 24 72 unnamed zeolite CEC 0 10 20 30 40 50 60 70 Time ( Hours) unnamed zeolite CEC Figure 5.4 Zeolite yield and CEC values produced for applying Hydrothermal treatment at 2.5N at 100 0C, at silica/ alumina ratio of 2.5.

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90 It could not be confirmed if katoite formation was as a result of the presence of excess silica a nd alumina in the system t hat reacted with calcium after the formation of unnamed zeolite or if both phases formed concurret. It has been reported by Catalfamo et. al., 1997, that calcium ions have high affinity for silicates and when present in high concentra tions ( < 3% ) it will interfere with, but not stop, zeolite formation. It is believed th at calcium ions react with silicates and bind to it. This in return will prevent the dissolution of the silicates into silicic acid (H4SiO4), a precursor to the formati on of the primary ions, Si(OH)4 that is needed for building zeolite structure. Howeve r, it was noticed t hat the amounts of unnamed zeolite formed were the same wit h or without the addition of aluminum, this can imply that active silica in the system, and not the added alumina, has dictated the amounts of unnam ed zeolite formation. Two factors could have led to the formation of katoite, first t he presence of high amounts of calcium carbonates and second the low activity of silica under used conditions. It seems that as alumina was added to the system calcium carbonates reacted with the silica and the alumina due the presence of hi gh concentration of alumina to form katoite first, then as the concentrations of aluminum and silica were reduced to the level that was before adding the aluminum, unnamed z eolite was formed. It is suggested that katoite formation preceded unnamed zeolite formation and this actually shows that the presence of im purities such as calcium carbonates do affect the reaction.

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91 Due to low zeolite yields and cons equently low CEC values (maximum ~ 68 meq/100g) obtained when the ash was treated hydrothermal process, it was concluded that hydrothermal treatment is not effective in dissolving and activating the silica sources present in the ash. T herefore, adding the fusion step to the process was thought to be an effective way to activate the ash particles. 5.1.2 Fusion prior to hydrothermal The formation of precursors such as sodium alumina silicate and sodium silicate phase are of importance to the form ation of zeolites su ch as zeolite X and A. Such precursors are expected to form by fusing the ash at high temperatures. In the present work this was found to be true, both sodium alumina silicate and sodium silicate (Table 4.6) were formed as the ash was subj ected to fusion at 5500C and phases such as zeolites X and A were formed later on during the hydrothermal reaction step as discussed in the following sections. 5.1.2.1 Hydrotherma l treatment at 100 0C for fused ash The fused ash was treated hydrotherma lly at the same conditions used when the ash was only treat ed hydrothermally. Figures 5.5 to 5.10 show different formed zeolites percentages and their CEC contributions to the total zeolitic produced materials for 1.5N, 2. 5N and 3.5N with silica/alumina ratio of 13.9 and 2.5, respectively.

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92 6 24 72 unnamed zeolite 1 CEC 0 20 40 60 80 100 120 Time ( Hours) A unnamed zeolite 1 CEC 6 24 72 unnamed zeolite CEC 0 20 40 60 80 100 120 Time ( Hours) B unnamed zeolite CEC 6 24 72 Zeolite X CEC 0 20 40 60 80 100 120 Time ( Hours) C Zeolite X CEC 6 24 72 Zeolite P1 CEC 0 20 40 60 80 100 120 Time ( Hours)D Zeolite P1 CEC 6 24 72 total zeolite Total CEC 0 20 40 60 80 100 120 140 160 180 Time ( Hours)E total zeolite Total CEC Figure 5.5 Zeolits percentages and their CEC contribution for fused ash treated hydrothermally at 1.5N at 100 0C for 6, 24 and 72 hours for silica/alumina ratio of 13.9. A) Unnamed zeolite 1, Na1.66AlSiO433 B)Unnamed zeolite, Na8Al6Si6O24(NO2)2.3H2O C)Zeolite X, (Na2Al2Si25O9.6.2H2O) D) Zeolite P1, Na6Al6Si10O32(H2O)12 E) Total Zeolite and CEC.

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93 For fused ash at 1.5N at silica/alumina ratio of 13.9 (Figure 5.5), zeolite X appeared at 72 (6.3 %) hours for the first time and z eolite P1 (13.44 %) was observed to form at that same period t oo. These results ar e in agreement with the results obtained by Tanaka et. al., 2002, 2003 and 2004, dur ing synthesis of zeolite from coal ash. Different forms of unmanned zeolites including unnamed zeolite with chemical composition of Na1.66AlSiO4.33 and Na8Al6Si6O24(NO2)2.3H2O were formed as major zeolites phases in this case, and their contribution to the CEC was the highest as shown in Figure 5.5. Zeolite X did not form when ash was tr eated only hydrothermally but it did form when ash was fused prior to hydrothe rmal reaction. This indicates that the presence of sodium alum ina silicate precursors such as unnamed zeolite Na1.66AlSiO4.33 (Figure 5.5A) within the formed gel matrix acted as a structure directing agents toward forming the doubl e six ring sub units, D6R, needed to connect the sodalite cages to build zeolit e X structure. Zeolite P1 was formed either by transformation of either zeolit e X or unnamed zeolite or both. Zeolite X and P1 formations were minimal and thei r contribution to the CEC values was consequently low (30.161.6 meq/100g). The maximum CEC value was obtained at 72 hours (164 meq/100 g) due to the pr esence of zeolite X, P1 and unnamed zeolite but the major contributi on came from unnamed zeolite. As silica/alumina ratio was adjusted to 2.5 for fused ash at 1.5N (Figure 5.6), zeolite A appeared for the first ti me at 6 hours and disappeared thereafter as shown in Figures 5.5 A and B. Zeo lite A did not form when ash was only treated hydrothermally.

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94 6 24 72 Zeolite A CEC 0 20 40 60 80 100 120 140 Time ( Hours) A Zeolite A CEC 6 24 72 Unnamed zeolite CEC 0 20 40 60 80 100 120 140 Time ( Hours)B Unnamed zeolite CEC 6 24 72 Total zeolite CEC 0 20 40 60 80 100 120 140 Time ( Hours) C Total zeolite CEC Figure 5.6 Zeolits percentages and their CEC contribution for fused ash treated hydrothermally at 1.5N at 100 0C for 6, 24 and 72 hours for silica/al umina ratio of 2.5. A) Zeolite A,Na96Al96Si96O384.216H20 B) Unnamedzeolite,Na8Al6Si6O24(NO2)2.3H2O C) Total Zeolite and CEC.

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95 In addition, it did not form w hen ash was fused without adjusting silica/alumina ratio. It wa s found that as the ash was fused and silica/alumina ratio was reduced, zeolite X or P1 did not form in this ca se and only unnamed zeolite and zeolite A were formed. It s eems that as silica/alumina was reduced from 13.9 to 2.5, zeolite X formation was prevented because silica /alumina ratio in this case was lower than that needed fo r zeolite X formation (< 3), and instead at this low ratio the reaction was direct ed toward forming double four rings sub unit, D4R, needed to connect sodalite cages to form zeolite A structure. Zeolite A was formed in very sm all amounts (1.98 %) and did not contribute much to the total CEC of the ash as shown in Figure 5.6, the maximum CEC obtained in this case wa s 131 meq/100g at 72 hours. It was found that for fused ash at 1.5N, as s ilica/alumina ratio was reduced to 2.5 the formation of zeolite was not in amounts higher than that obtained for silica/alumina ratio of 13.9. The reason fo r not forming high amounts of zeolite is that silica sources in the ash, namely quartz, glass and porcelain, may have not been activated enough to react with the ad ded aluminum. This was confirmed by the precipitation of alumi na hydroxide, gibbsite and bayerite, as a result of the presence of excess aluminum in solution. Increasing the hydroxide concentrat ion in the system was found to be critical to insure dissoluti on of silica and aluminum so urces. As sodium hydroxide concentration increased from 1.5N to 2.5N at silica/alumina ratio of 13.9, unnamed zeolites,Na6Al4Si4O17 and Na8Al6Si6O24(NO2)2.3H2O, were formed as shown in Figure 5.7. T he maximum CEC value obtai ned in this case was

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96 191meq/100g at 72 hours; this value wa s 30 meq/100g (~ 15%) more than that obtained for fused ash at 1.5N. Zeolite X did not appear in this case due the change in the silica/alumina ratio as a result of increasing the hydroxide concentration which dissolutes more silica. Meanwhile zeolite P1 was formed at 72 hours with significant amounts that result ed in increase in the CEC value at 72 hours. For adjusted silica/alumina ratio of 2.5, zeolite A was formed at 6, 24 and 72 hours at 2.5N in significant amount s and its percentage was increased from 1.98% for fused ash at 1.5N up to 28.5 % for fused ash at 2.5 N at 6 hours, as shown in Figure 5.8. As the reaction ti me was increased, zeolite A was reduced down to 11.8% after 72 hours. The reducti on in zeolite A formation at prolonged reaction time is expected si nce zeolite A is known to be a meta-stable phase that transform into more stable zeolite such as sodalite. Zeolite A is known to form usually within the first hours of the r eaction and at high temperature, high hydroxide solution and at lo ng time it tends to transform into other phases such as sodalite phase. The finding of the pr esent study was in agreement with the results of the work that has been done by Subotic et. al., 1985, and Grujic et. al., 1989, in synthesizing zeolit e from pure chemical com pounds. Stamboliev et. al., 1985 findings were similar when zeolite A was synthes ized from coal ash. In addition, Myake et. al., 2002, observed the same trend wh en zeolite A was synthesized from MSW fly ash. Sodalite formation was due to relatively high temperature, 1000C, used and probably the presence of high concentrations of carbonates as will be explained in later sections.

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97 6 24 72 Unamed zeolite 1 CEC 0 20 40 60 80 100 120 140 160 180 200 Time ( Hours)A Unamed zeolite 1 CEC 6 24 72 Unamed zeolite CEC 0 20 40 60 80 100 120 140 160 180 200 Time ( Hours)B Unamed zeolite CEC 6 24 72 Zeolite P1 CEC 0 20 40 60 80 100 120 140 160 180 200 Time ( Hours)C Zeolite P1 CEC 6 24 72 Unamed zeolite CEC 0 20 40 60 80 100 120 140 160 180 200 Time ( Hours) B Unamed zeolite CEC Figure 5.7 Zeolites percentages and their CEC cont ribution for fused ash treated hydrothermally at 2.5N at 100 0C for 6, 24 and 72 hours for silica/ alum ina ratio of 13.9. A) Unnamed zeolite 1, Na6Al4Si4O17 B) Unnamed zeolite, Na8Al6Si6O24(NO2)2.3H2O C) Zeolite P1 D) Total Zeolite and CEC.

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98 6 24 72 Zeolite A CEC 0 20 40 60 80 100 120 140 160 180 200 Time ( Hours)A Zeolite A CEC 6 24 72 unnamed zeolite CEC 0 20 40 60 80 100 120 140 160 180 200 Time ( Hours)B unnamed zeolite CEC 6 24 72 Zeolite ZK-14 CEC 0 20 40 60 80 100 120 140 160 180 200 Time ( Hours) C Zeolite ZK-14 CEC 6 24 72 Sodalite CEC 0 20 40 60 80 100 120 140 160 180 200 Time ( Hours) D Sodalite CEC 6 24 72 Total zeolite CEC 0 20 40 60 80 100 120 140 160 180 200 Time ( Hours)E Total zeolite CEC Figure 5.8 Zeolites percentages and their CEC cont ribution for fused ash treated hydrothermally at 2.5N at 100 0C for 6, 24 and 72 hours for silica/ al umina ratio of 2.5. A) Zeolite A, Na96Al96Si96O384.216H20 B) Unnamed zeolite, Na8Al6Si6O24(NO2)2.3H2O C) Zeolite Zk-14, Na3.68Al3.6Si8.4O24.H2O D) Sodalite, Na8Al6Si6O24(NO2)(CO3)0.5 E) Total zeolite and CEC.

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99 Neither gibbsite nor bayerite were f ound to form in this case which indicates that at 2.5N fusion the amount of reactive silica is higher than that obtained for fused ash at 1.5 and accord ingly all the added alumina reacted with the silica. This can be confirmed by t he increase in zeolite A formation and the lack of formation of non zeolite phase katoit e. The lack of formation of katoite phase indicated that the solu tion was super saturated with silica and aluminum which created driving force for zeolite A formation and overcome the competition with calcium carbonate in the system. The formation of zeolite A at 6 hours increased the CEC of the total ash produced up to 193.28 meq/100g. The CE C value for zeolite A increased from 10.7 meq/100g for fused ash at 1.5N up to 155.9 meq/100g for fused ash at 2.5N. Other zeolite phases formed in this case were zeolite ZK14 (Na3.68Al3.6Si8.4O24.H2O) that was formed with perc entage of 8.8% and CEC value of 34.1 meq/100g at 6 hours, unnamed zeolite (Na8Al6Si6O24(NO2)2.3H2O) which was formed with percentage of 12.54 % and CEC value of 10 1 meq/100g at 24 hours, and finally sodalite (Na8Al6Si6O24(NO2)(CO3)0.5) which was formed with percentage of 16.47% and CE C value of 135.4 meq/ 100g at 72 hours. Sodalite was found to be the second major phase that contributes to the CEC value of the ash. For fused ash at 3.5N at silica /alumi na ratios of 13.9 and 2.5, the zeolites phases that were formed were as those t hat were formed when ash was fused at 2.5N. An exception was that zeolite Zk-1 4 did not appear at all at 3.5N and P, Na1.4Al2Si3.9O11.5.H2O was formed at 24 and 72 hours at silica/alumina ratio of

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100 13.9. Figures 5.9 and 5.10 show z eolites percentages and their CEC contributions for ash fused at 3.5N with silica/alumina ra tios 13.9 and 2.5, respectively. A comparison between fusing the ash at 2.5N and 3.5N and at silica/alumina ratio of 2.5 for zeolite A formation shows that zeolite A formation has decreased as alkalinity of the solution was increased. It was found that when zeolite A formation is decreasing, sodalit e formation tends to increase. This indicate that Zeolite A is to transforming into sodalite. In general the total CEC value was decreased when ash was treated at 3.5N, maximum 167 meq/100g at 72 hours, and this indicate s that high alkalinity did not improve the formation of different zeolite types. It seems that fusion at 2.5N was the optimum condition when hy drothermal reaction was performed at 100 0C. Both zeolite A and sodalite has almost similar structure that consists of primarily connected s odalite cages except that z eolite A sodalite cages are connected to each other via D4R sub unit ring. Figure 5.11 shows zeolite A and sodalite structures as descri bed by Dyer, 1988. It is believed that D4R sub unit ring tends to dissolve at hi gh temperature and at high alkalinity. This is because of the presence of high hydr oxyl ion (OH) that usually attacks Al-O-Al bridges in zeolite structure and that is postulated why zeolite A transforms into sodalite.

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101 6 24 72 unnamed zeolite CEC 0 20 40 60 80 100 120 140 160 180 200 Time ( Hours)A unnamed zeolite CEC 6 24 72 Zeolite P CEC 0 20 40 60 80 100 120 140 160 180 200 Time ( Hours) B Zeolite P CEC 6 24 72 Total zeolite Total CEC 0 20 40 60 80 100 120 140 160 180 200 Time ( Hours) C Total zeolite Total CEC Figure 5.9 Zeolites percentages and their CEC cont ribution for fused ash treated hydrothermally at 3.5N at 100 0C for 6, 24 and 72 hours for silica/ alumina ratio of 13.9. A) Unnamed zeolite, Na8Al6Si6O24(NO2)2.3H2O B) Zeolite P, Na1.4Al2Si3.9O115.H2O C) Total zeolite and CEC.

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102 6 24 72 Zeolite A CEC 0 20 40 60 80 100 120 140 160 180 200 Time ( Hours)A Zeolite A CEC 6 24 72 Unnamed zeolite CEC 0 20 40 60 80 100 120 140 160 180 200 Time ( Hours)B Unnamed zeolite CEC 6 24 72 Sodalite CEC 0 20 40 60 80 100 120 140 160 180 200 Time ( Hours) C Sodalite CEC 6 24 72 Total zeolite Total CEC 0 20 40 60 80 100 120 140 160 180 200 Time ( Hours)D Total zeolite Total CEC Figure 5.10 Zeolites percentages and their CEC cont ribution for fused ash treated hydrothermally at 3.5N at 100 0C for 6, 24 and 72 hours for silica/ al umina ratio of 2.5. A) Zeolite A, Na96Al96Si96O384.216H20 B) Unnamed zeolite, Na8Al6Si6O24(NO2)2.3H2O C) Sodalite, Na8Al6Si6O24(NO2)(CO3)05 and D) Total zeolite and CEC.

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103 The SEM images for zeolite A showed t hat large crystals, 0.7-1.2 m, of zeolite A formed only when ash was fus ed at 2.5N, while smaller crystal, 0.540.81 m, was formed when ash was fused ash at 3.5N. Smal l crystals usually form due to rapid formation of the nuclei at high temperatures, or it could be due to preventing further growth of the cr ystals caused by hydroxyl attack on the formed nuclei. It is possible that both r easons can cause small crystal formation at 3.5N. On the other hand, larger crystal obtained at 2.5N may be due to the less hydroxyl attack on zeolite nuclei. The transformation of zeolite A suggests that zeolite A synthesis process is metastable and it shows that reaction time is a decisive factor in the synthesis process especially at high temperature and alkalinity. These findings are in agreement with previous literature on zeolite A formation. Figure 5.11 Structures of zeolite A and sodalite. A) Zeolite A, D4R B) sodalite. Dyer, 1988. A B

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104 In summary, it was found that for ash treated hydrothermally at 100 0C, fusing the ash at 1.5N was not enough to activate silic a and alumina in the ash particles. This was confirmed by the precipitation of alumina added to the reaction system in the form of alumina hydr oxide, (gibbsie and bayerite). On the other hand, as the ash was fused at 2. 5N and 3.5N, zeolit e A was formed in significant amounts with optim um results obtained at 2.5N. The increase in zeolitic materials formation w hen fusing the ash at 2.5N indicted that increasing the hydroxide content resulted in the di ssolution of more silica and made it available for reaction. Zeolite A formation was always associated with silica/alumina reduction. This confirms that the silica/alum ina ratio of the original ash, 13.9, was high and not suitable for z eolite A formation, this finding is of importance since it provides key for c ontrolling and optimizati on the process of zeolite A formation. The reduction in zeol itic materials formation as hydroxide content was increased by fusing the ash at 3.5N resulted from hydroxyl attack to Al-O-Al bridges in zeolite A structure. It was found that reaction time is important for zeolite A formation, and in this particu lar study and at the used conditions it was found that 6 hours seems to be th e best for zeolite A formation for ash treated at 100 oC. Finally, sodalite formation wa s indicative that the used temperature was high which resulted in rapid dissolution of zeolite A at high alkalinity. Therefore, the hydrotherma l temperature was reduced from 100 0C to 60 oC as discussed in the next section.

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105 5.1.2.2 Hydrotherma l treatment at 60 0C for fused ash As the hydrothermal reaction te mperature was reduced from 1000C down to 600C, an increase in zeolite A formati on was observed when silica/alumina ratio was reduced. Figure 5.12 show s zeolite percentages and their CEC contributions for fused ash at 1.5N for silica/alumina ratio of 13.9. Only unnamed zeolite, Na8Al6Si6O24(NO2)2.3H2O, was formed in this case in low amounts with no significant changes on increasing the reaction time to 72 hours. The CEC values, maximum 92 meq/100g at 72 hours, were lower than those observed when samples were treated at a 1000C. This is due to the fact that there is no much reactive silica available for reac tion and by lowering the temperature the reaction was further slowed down. As silica/alumina ratio was reduced to 2.5N, zeolite A formed at higher percentages at 600C than it did at 1000C and it was more stable at the lower temperature, as shown in Figure 5.13. However, zeolite A per centages were still very low, 3.797.86 %, and therefor e their contribution to the CEC was negligible. In this case only unnamed zeol ite was present with zeolite A in low percentages which affected the overall CEC values (57-102 meq/100g). These results were expected since at 1.5N, the sili ca in the ash particles is not active as concluded from the re sults observed at 100 0C. This also was confirmed by the precipitation of excess al umina added in the form of gibbsite and bayerite.

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106 SEM images for fused ash at 1.5N at 60oC showed that zeolite A crystal sizes were small, in the range of 0.5-0.62 m, this co uld be due to the lack of active silica in the ash at these condition s which resulted in lim iting the growth of zeolite A crystals. For fused ash at 2.5N and at silica/ alumina ratio of 13.9, unnamed zeolite was formed with chemical compositions of Na2Al2Si1.68O7.76.1.73H2O and Na6Al4Si4O17 as shown in Figure 5.14. The zeolite percentages and their CEC values in this case were less than that observed at 1000C reaction temperature. These lower values were obtained due to the formation of low amounts of unnamed zeolites, probably as a result of lowering the temperature. As silica/alumina ratio was adjusted to 2.5, zeolite A was formed in significant amounts, 20.638.8%, and the CEC of zeo lite A were high, 112.7212.8 meq/100g, as shown in Figure 5.15. It was found that the optimum condition for zeolite A formation was at 24 hours, this was not the case when the reaction temperature was 100oC where the optimum time was 6 hours. As the reaction temperature decreased, time s hould be increased to allow crystals to grow. SEM images showed that zeolite A crystals formed for fused ash at 2.5N at 60oC has the largest crystals sizes, 1. 1-1.6 m, observed during the present study. The larger crystal sizes obtained in th is case indicate that treating the ash at 60oC is more favorable for zeolite A formation than treatment at 100oC though it required more time for cr ystal growth. These results are expected since zeolites of low density and high volume, such as z eolite A, require low energy to form and they tend to transform into denser zeolites such

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107 6 24 72 unnamed zeolite CEC 0 20 40 60 80 100 120 Time ( Hours) unnamed zeolite CEC Figure 5.12 Unnamed zeolite, Na8Al6Si6O24(NO2)2.3H2O formation and its CEC values at 1.5N at 60 oC and silica/alumina ratio of 13.9. 6 24 72 Zeolite A CEC 0 20 40 60 80 100 120 140 Time ( Hours)A Zeolite A CEC 6 24 72 unnamed zeolite 2 CEC 0 20 40 60 80 100 120 140 Time ( Hours)B unnamed zeolite 2 CEC 6 24 72 Total zeolite Total CEC 0 20 40 60 80 100 120 140 Time ( Hours)C Total zeolite Total CEC Figure 5.13 Zeolite formation and their CEC values at 1.5N at 60 oC and silica/alumina ratio of 2.5. A) Zeolite A, Na96Al96Si96O384.216H20 B) Unnamed zeolite, Na2Al2Si168O7.76.1.73H2O C) Total zeolite.

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108 6 24 72 unnamed zeolite 3 CEC 0 20 40 60 80 100 120 140 160 180 Time ( Hours)A unnamed zeolite 3 CEC 6 24 72 unnamed zeolite CEC 0 20 40 60 80 100 120 140 160 180 Time ( Hours)B unnamed zeolite CEC 6 24 72 Total zeolite CEC 0 20 40 60 80 100 120 140 160 180 Time ( Hours)C Total zeolite CEC Figure 5.14 Zeolite formation and their CEC values at 2.5N at 60 oC and silica/alumina ratio of 13.9. A) Unnamed zeolite 3, Na6Al4Si4O17 B) Unnamed zeolite, Na2Al2Si1.68O7.76.1.73H2O C) Total zeolite.

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109 6 24 72 Zeolite A CEC 0 20 40 60 80 100 120 140 160 180 200 220 240 Time ( Hours)A Zeolite A CEC 6 24 72 Unnamed zeolite CEC 0 20 40 60 80 100 120 140 160 180 200 220 240 Time ( Hours)B Unnamed zeolite CEC 6 24 72 Zeolite Zk-14 CEC 0 20 40 60 80 100 120 140 160 180 200 220 240 Time ( Hours)C Zeolite Zk-14 CEC 6 24 72 Total zeolite CEC 0 20 40 60 80 100 120 140 160 180 200 220 240 Time ( Hours)D Total zeolite CEC Figure 5.15 Zeolite formation and their CEC values at 2.5N at 60 oC and Silica/alumina ratio of 2.5. A) Zeolite A, Na96Al96Si96O384.216H20 B) Unnamed zeolite, Na2Al2Si168O7.76.1.73H2O C) Zk14, Na3.68Al3.6Si8.4O24.H2O D) Total zeolite.

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110 as sodalite at higher temper atures. Other zeolite formed in this case was Zk-14 with percentage close of 6.5 % and low CEC value, 25 meq/100g. Also, unnamed zeolite, Na2Al2Si1.68O7.76.1.73H2O, was formed with percentage close to 12% and CEC value of 97.6 meq/100g. The overall CEC value obtained in th is case was 237.4 meq/100g at 24 hours. This value is close to those repor ted for commercial zeolites which usually have a CEC values in the range of 240 to 400 meq/100g. The lack of formation of sodalite in this case indicates th at hydrothermal treatment at 60 oC was suitable for the formation of stable zeolite A and th erefore zeolite A did not transform into the dense form sodalite. Figures 5.16 and 5.17 show zeo lites percentages and their CEC contribution for fused ash at 3.5N and at 60oC with silica/alumin a ratio of 13.9 and 2.5, respectively. As shown in Figur e 5.16 for silica/alumina ratio of 13.9, only unnamed zeolite, Na2Al2Si1.68O7.76.1.73H2O, was formed in low amounts, 11%, with low CEC values, 86 meq/100g. Zeolite P which formed at 100 oC was absent at 60 oC. This is because zeolite P forma tion requires higher temperature to form. It was noticed that at lower temperature, 60 oC, and for silica/alumina ratio of 13.9, zeolites yields were always less than it is for higher temperatures, 100 oC. This concludes that the types of zeolite that can form at this silica/alumina ratio, nam ely unnamed zeolite and zeo lite P, require higher temperature to stabilize. This finding is of importance because it indicates that it is better to use lower temperature to e liminate or reduce the formation of such zeolites if they are not desired phas es during the synthesis process.

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111 6 24 72 Unnamed zeolite CEC 0 20 40 60 80 100 120 140 160 180 200 220 Time ( Hours)A Unnamed zeolite CEC 6 24 72 Total zeolite Total CEC 0 20 40 60 80 100 120 140 160 180 200 220 Time ( Hours)B Total zeolite Total CEC Figure 5.16 Zeolite formation and their CEC values at 3.5N at 60 oC and silica/alumina ratio of 13.9. A) Unnamed Zeolite, Na2Al2Si1.68O7.76.1.73H2O B) Total zeolite. 6 24 72 Zeolite A CEC 0 20 40 60 80 100 120 140 160 180 200 220 240 260 Time ( Hours)A Zeolite A CEC 6 24 72 Unnamed zeolite CEC 0 20 40 60 80 100 120 140 160 180 200 220 240 260 Time ( Hours)B Unnamed zeolite CEC 6 24 72 Total zeolite Total CEC 0 20 40 60 80 100 120 140 160 180 200 220 240 260 Time ( Hours)C Total zeolite Total CEC Figure 5.17 Zeolite formation and their CEC values at 3.5N at 60 oC and silica/alumina ratio of 2.5. A) Zeolite A, Na96Al96Si96O384.216H2O B) Unnamed zeolite, Na2Al2Si1.68O7.76.1.73H2O C) Total zeolite.

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112 Zeolite A formation for fused ash at 3.5N with silica/alumina ratio of 2.5 at 600C was higher and more stabl e than that formed at 1000C with optimum value at 24 hours. These results are in agreem ent with the results obtained when ash was fused at 2.5N. The only difference wa s in the amounts of Zeolite A produced at 3.5N which was slightly less than t hat produced at 2.5N. Zeolite A was found to form as a major phase when fusing the ash at 2.5N and 3.5N at 600C for 24 hours. The maximum CEC value, 245 meq/100 g, obtained in this study was at 3.5N and at 72 hours. Despite the fact that this value is in the lower edge of available commercial zeolites, there is still a potential for commercial usage of the produced zeolitic materials obt ained in this study. In summary, it was found that it is necessary to fuse the ash prior to hydrothermal reaction in order to pr oduce zeolite A as well as reducing silica/alumina ratio. Also it was found t hat to obtain higher am ounts of zeolite A, operating temperatures should be lower than 1000C. The optimum operating conditions for zeolite A formation were at 600C for 24 hours for fused ash at 2.5N and with silica/alumina ratio of 2.5. It was also found that reducing reaction temperature resulted in reduction in t he formation of other undesired zeolite phases. Due to increase in zeolite A phas e, the CEC of the ash was improved with maximum value of 245.0 meq/100g whic h is considered wit hin the range of available commercial zeolite. This is an encouraging result to seek possible applications for the ash for either industry or solvin g environmental problems.

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113 5.1.3 Summary The findings of this study indicate that hydrothermal treatment is inefficient in activating the ash particles of total MSW. The outcome of such treatment was the formation of low amounts of unnam ed zeolites with low CEC values regardless of what conditions are used. T herefore, it was necessary to fuse the ash prior to hydrothermal treatment to insu re the dissolution of ash particles and formation of zeolite precursors. Zeolite pr ecursors formed as a result of fusion included sodium alumina silicate, sodium silicate and sodium alumina silicate hydrate. Mainly, unnamed zeolites and zeolit e A were the major phases to form fused ash. Zeolites X, P1 and Zk-14 were formed at silica/alumina ratios of 13.9 and 2.5, respectively, and their formation was rare and in low amounts, except for zeolite P1. Sodalite was formed as a result of transformation of zeolite A; this was noticed to occur at high temperatur e and high alkaline cond ition, 3.5N, and at prolonged reaction time. Zeolite P1 was formed at high temperature and relatively low alkaline conditions, 1.5N -2.5N, and at high silica/alumina ratio. Silica/alumina ratio was found to be a deci sive factor in pr oducing zeolite A as well as other zeolite types such as ze olite Zk-14 where it was necessary to reduce silica/alumina ratio down to 2. 5 to produce these zeolites. The hydroxide content and reaction te mperature were bo th important and interrelated factors in zeolite formation. The presence of low hydroxide content as the ash was fused at 1.5N was not eno ugh to activate silica sources in the ash, namely glass, quartz and porcelain Therefore, zeolite formation was

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114 minimal regardless of temperature used at low hydroxyl content. On the other hand, at higher hydroxide content when the ash was fused at 2.5N and 3.5N, zeolites formation was f ound to be preferentially dep endant on the temperature and time used in this case. In general, it was found that zeolite A formation was favorable at 24 hours at 600C with high amounts and lar ge crystal sizes, whereas zeolite formation was favo rable at 6 hours at 1000C with less amounts and smaller crystal sizes than t hat obtained at 24 hours at 600C. From these results, it is clear that the optimum conditions to produce higher amount s of zeolite A and reducing the formation of other zeolite phases should consider operating at silica/alumina ratio of 2.5, temperature of 600C and hydroxide concentration of 2.5N or 3.5N. At optimum conditions, the highes t CEC values obtained were 237.4 meq/100g and 245.4 m eq/100g as a result of the form ation of zeolit e A and other zeolites. These values are close to the CEC values of commercial zeolites, 240400 meq/100g. 5.2 Zeolite A Formation, Theory and Mechanism Zeolites formation is a complicated pr ocess in its nature because of the presence of diverse zeolite structures that can form and because the presence of many factors that affect these structur es formation. The most important factors involved in zeolite synthesis include i) silica/alumina rati o ii) crystallization temperature iii) crystallizat ion time iv) alkali (such as Na, Ca and K) and ionic species content (such as CO3 -2, NOand Cl-) v) aging and vi) stirring.

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115 Zeolite A formation, in particular, has received special attention by researchers due its usage in wide applicatio ns. Zeolite A formation is believed to form via two possible mechanisms including 1) crystallization from clear solution, via interaction between soluble species and 2) transformation of gel phase, either through solid-solid or via solution mediated transport mechanism. In general, zeolite A formation via gel phase is a wi dely accepted theory among researchers. However, it has always been difficult to study the mechanism of zeolite formation from gel due to the complexity of its microstructure. Therefore, the exact mechanism for zeolite A formation ha s not yet been fully established. Nevertheless, with the aid of sophisticated techniques such as using scanning electron microscopy, X-Ray diffraction, NMR, transmission electron microscopy, light scattering microscopy and IR spectr oscopy it was possible to explore and follow zeolite A nucleation and growth. Most of these techniques are useful when studying zeolite A formation from pure ch emical compounds due to simplicity of such systems where only clear solution and gel are involved. However, most of these techniques are not applicable when studying zeolite synthesis from complex systems such as coal ash and MSW. The reason for the nonapplicability of some techniq ues is that the complex systems have many phases involved in this case including solid, liqui d and gel with high im purities the thing that may interfere with the re sults (Shigemoto et. al, 1995). Of the above mentioned techniques, scanning electron microscopy and XRay diffraction are the most suitable tech niques that can be used to assist in studying zeolites synthesis mechanism from the complex system considered in

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116 this study. Accordingly, zeolite A mec hanism of formation was studied using Xray analysis and SEM observation in the present study. 5.2.1 The role of fusion versus hydrothermal in zeolite A formation It was found that zeolite A was formed only when samples were fused at high temperature. In spit of the fact that s ilica/alumina was reduced to 2.5, during hydrothermal reaction for samples that were not fused, zeolite A did not form at any used condition as it did when samples were fused. In order to answer the question why zeolite A forms when ash is subjected to fusion prior to hydrothermal but it does not form if the ash is used directly without fusion, it is important first to look at the starting materials in each case. Looking back at the starting ma terial of the ash that wa s not fused, the possible sources for silica and alumina in this case were quartz, glass and porcelain particles. It appears that these sources were not active enough to provide silica, in particular, that is needed to reac t with the added aluminates. Instead, unnamed zeolites of sodalite structure were formed, with the general chemical formula of Na8Al6Si6O24 (NO2)2.xH2O, and in low amounts. The presence of nitrates (NO2) in the reaction system and the lack of enough reactive silica in the system has directed the reaction toward forming unnamed zeolite in low amounts and prevented the formation of zeolite A in this case. It has been reported by Armstrong and Dann, 2000, that the presence of carbonates (CO3) and nitrates (NO2) will actually work as a template for sodalite cages to build itself around. Results obtai ned in this study are in agreement with these findings. Additionally, the formation of katoite suggests that the presence of

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117 calcium, Ca, has affected the reaction by competing with sodium ions and bonded itself to the silicate in the systems and reduced t he chances for zeolites formation. As the ash was subjected to fusion, both chemistry and morphology of the ash were changed significantly where new phases were formed as shown in Table 4.6. An important phase has formed in this case was sodium silicates (Na2SiO3) at 2.5N and 3.3N but not for fused as h at 1.5N; it could be that this phase did actually form at 1.5N but in very small amounts that was below the detection limit of the x-ray di ffraction. That explains the low amounts of zeolite A formed at 1.5N fused ash. Other im portant phases formed were sodium aluminum silicates with chem ical composition of NaAlSiO4. This phase was formed at 1.5N fusion only. At 3.5N, sodium aluminum s ilicate hydrate with chemical composition of Na2Al2Si1.68.O7.76.1.73H2O was formed. The formation of sodium silicate and sodium aluminum s ilicates phases are im portant precursors for zeolite A formation. The morphology of the ash has al so changed from sharp scattered particles into aggregations or clusters of porous aluminum silicate gel particles. The alumina silicate gel could not be detec ted by the X-Ray diffraction but it was observed in SEM images. Sodium silicat e was observed by SEM images to have a needle like structure and it was found to be mixed within the gel particles. Zeolite A was found always to form imbedded within the pores of these clusters and attached to surface of the gel particles.

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118 Figure 5.18 shows SEM images for t he sequence of zeolite A formation. SEM images for fused and hydrothermally treated fused ash at 2.5N were used as an example to study zeolite A formation sequence. As shown in Figure 5.18, right after fusion the ash particles have dissolved at high temperature and high alkalinity and transformed into sodium aluminum silicate gel clusters as shown in Figure 5.18B, the clusters were of irregular shapes and approximately 200 m in lengt h. Within these clusters the gel particles were observed to be also of i rregular shapes with different lengths, less than 20 m as shown in Figure 5.18C. Sodium silicate was found to penetrate the gel particles with needle like shape of less than 15 m in length as shown in Figure 5.18D. This phase was found to disappear when the fused ash was subjected to hydrothermal reaction right after fusion. It seems that sodium silicate is dissoluted during hydrothermal reaction step to form monom eric species as follows: Na2SiO3 OH 2Na + SiO3 -2 Or Na2SiO3 OH 2Na + Si(OH)4 These reactive forms of silicate were av ailable in solution to react with the added sodium aluminates; aluminates were available in the form of Al(OH)4 due to the dissolution of sodium aluminates as follows: NaAlO.xH2O OH Al(OH)4

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119 Figure 5.18 SEM images for Zeolite A sequence of formation. A) Non-treated ash B) Fused ash at 2.5N, gel particles aggregations C) Gel partic les D) Sodium silicate within gel aggregations (needle like) E) Zeolite A formation at 6 hours, star t of nucleation F) Large crystals of zeolite A at 24 hours. D C B A E F

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120 With the presence of the right silica/alumina ratio in solution and in the presence of sodium and water molecules, both Si(OH)4 and Al(OH)4 reacted to form SiO4 and AlO4 tetrahedral structure which ar e the primary building block for any zeolite structure. Sodi um ions act as a structur e directing agent and water molecules acted as a structural support. Zeolite A nucleation seems to occur at the inter phase between gel pa rticles and solution as sh own in Figure 5.18E. As the reaction time proceed zeolite A crystal s continued growing within the pores of the gel clusters through consuming nut rients as they dissolved from the gel phase or from solution as shown in fi gure 5.18F. The reaction then ceases once all species in the solution and gel are consumed or decreased below the concentration that required for continuing th e growth. Super saturation of silicate and aluminates were the driving force for the formation of zeo lite A structure. 5.2.2 Mechanism of zeolite A formation There are two possible theories for zeolite A formation in the present study. First, it is possible that zeolit e A nuclei formation was triggered by the formation of D4R sub unit in the solution first by interaction between the added aluminates and the formed sodium silicat e. These subunits react with sodalite cages, formed in the gel phase, to build z eolite A structure. This possible path for zeolite A formation is in agreement with that suggested by Melchior, 1983, who suggested a possible path for zeolite A formation as shown in Figure 5.19.

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121 Figure 5.19 Zeolite A path of formation, Melchior, 1983. The second theory is that zeolite A nuc lei were formed solely in solution as sodium silicates reacted spontaneous ly with the added aluminates to form nuclei of zeolite A. the nuc lei continue their growth by consuming nutrients from the gel phase or the solution phase. It was not possible to know for sure which path was taken by zeolite A in its formation, but it can be said that the formation of sodium silicate within t he gel and the addition of sodium aluminates were key factors for initiating nuclei for zeolite A to form. So in the present study it can be concluded that mechanism of zeolite A formation is considered as solution transport mediated process that involved both gel and solution interaction rather than being pure solution reacti on or pure gel transformat ion process. Figure 5.20 shows schematic presentation for possibl e paths for zeolite A formation.

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122 Figure 5.20 Schematic presentations fo r zeolite A formation process. During the synthesis of zeolite A, t here was always a limit for zeolite A formation and with the best cases no more than almost 38.8 % of zeolite A formation could be achieved and there was always zeolite of so dalitic structure associated zeolite A formation. It s eems that the presenc e of carbonate and nitrate negatively affected zeolite A forma tion by directing the reaction toward forming sodalite structure. This effect was more intense when the ash was fused at 3.5N. This is probably due to the increas e in the pH which in return increased the activity of the carbonates, CO3 -2 in the reaction system. However, the lack of achieving high concentrations of zeolit e A could be due to depletion of the nutrients or changing in sili ca/alumina ratio in the system rather than competition with other zeolite types. It wa s not possible to clarify this point within the scope of the present work. Gel cluster Gel particles Sodium silicate (Na2SiO3) OH Na Sodium aluminates (NaAlO.xH2O) Solid phase Solution phase + Solidsolution interaction Zeolite A Crystals Si ( OH ) 4 Al ( OH ) 4 + Non-reacted gel particles

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123 5.3 Experimental Design Analysis, M odeling of Zeolite A Formation The experimental design analysis performed to examine zeolite A formation under different used conditions was successful in establishing the relationship between the used differ ent conditions, namely hydroxide concentration, temperature and time. However, it should be taken into consideration that the obtained yield equat ions have constraints and they mostly present a simple primary m odel that aimed to estab lish and explore a possible trend for zeolite A formation from MSW. Th is model is not an actual general model that can be used practically to calc ulate zeolite A yield in any synthesis process. The reason for the restrictions in using such model is the complexity associated with zeolite A formation proc ess due to the presence of many factors that affect the synthesis process. For example, silica/alumina ratio and nutrients concentrations are two important factors that should be included in any model used to predict an actual production of zeolite A from a specific synthesis process. Silica/alumina ratio was fixed at 2.5 in the pr esent study and therefore it could not be included as a variable in the model. Also, nutrients concentrations were not adjusted during the study and they were fixed to that originally present in the reaction systems and therefore they were not variables as well. Nevertheless, the model has showed a strong relati onship between the three different variables examined as discu ssed in the following sections.

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124 5.3.1 Model constraints The yield equations used to model z eolite A formation at hydroxide concentrations between 1.5N to 3. 5N have the following constrains: 6 < t < 24, where t is time, hours. And 60 < T < 100, where T is temperature, oC. The following sections will discuss the meanings and implications of the obtained yield equations and will address the effect of different conditions used on zeolite A formation. 5.3.2 Effect of hydroxide concentrations The yield equations for zeolite A fo rmation obtained for cycle 1 and 2 described in chapter 4, respectively, are: Ycycle1 = 14.4 + (22.26/2)N + (1.7 1/2)Nt + (0.34/2)t (6 .53/2)T (1.87/2)NT (9.67/2)Tt (6.47/2)NTt (equation 4.2) And Ycycle2 = 21.63 (7.75/2)N + (5. 43/2)Nt + (3.45/2)t (6 .63/2)T + (1.7/2)NT (15.22/2)Tt (1/2)NTt (equation 4.3) Figures 5.21 and 5.22 show the normal probabilit y plots for yield equation coefficients for cycle 1 and cycle 2. The effe ct of sodium hydr oxide concentration on zeolite A formation was sign ificant for 1.5N and 2.5N, cycle 1, than it is for 2.5N and 3.5N, cycle 2, as shown in figures 5.21 and 5.22.

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125 Figure 5.21 Normal probability plot for cycle 1, for 1.5N and 2.5N. Figure 5.22 Normal probability plot for cycle 2, for 2.5N and 3.5N.

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126 The yield equations showed that zeolite A synthesis process is sensitive to the amounts of added sodium hydroxide. As indicated from the coefficients for hydroxide concentrations, N, in equations 4.2 and 4.3, it was found that in general as the hydroxide concentration increa ses above 2.5N this translates into decrease in zeolite A yield as indicated by the negative sign in the yield equation for cycle 2 (-7.75/2). The decreas e in zeolite A yield indica tes that there is a limit for how much hydroxide should be added to the system. This finding is justified by the fact that zeolite A nuclei cannot survive at hi gh hydroxide concentrations due to hydroxide attack on t he Al-O-Al bond in the te trahedral primary building block of zeolite A structur e (Antonic and Subotic, 1997). This was confirmed from the high positive coefficient for N ( 22.26/2) for cycle 1 where hydroxide concentration was between 1.5N and 2.5N which showed higher positive effect on zeolite A formation than that obtai ned when hydroxide concentration was between 2.5N and 3.5N (-7.75/2). Increasing the hydroxide concentr ation was found to have an adverse effect on zeolite A nuclei formation; this comes in spite of the fact that adding more hydroxide will insure dissolutions of the refractory phases in the ash. The yield equations also suggest that zeolit e A synthesis process is actually an optimization process where hydroxide concentration is considered a second key factor in the synthesis proce ss after silica/alumina ratio.

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127 5.3.3 Effect of temperature and time It was found that time for zeolite A formation is dependant on temperature used. The effect of time and temperat ure on zeolite A forma tion were profound when sodium hydroxide concentration was increased as shown in figures 5.21 and 5.22. In general, at hi gher hydroxide concentrati on the interaction between time and temperature indicates that as temperature increases zeolite A yield increases with decreasing reaction time as indicated by the positive effect of the interaction of NT (+1.7/2) for cycle 2. Meanwhile, the yield decreases at high temperatures if reaction time is prolonged as indicated by the high negative interaction coefficient fo r Tt for cycle 2 (-15.22/2). Increasing the temperature was found to negatively affect zeolite A yield at higher hydroxide concentrations, this comes in spite of the fact that increasing the temp erature of the reaction will reduce the time required for zeolite A formation. It was found that zeolite synthesis in general is more favorable at 60 0C than at 100 0C. This can be explained by the fact that at high temper atures other zeolit e phases such as sodalite and zeolite P are mo st likely to compete with z eolite A which may hinder the nucleation and formation of zeo lite A at higher temperatures. So zeolite A formation is actually a temperature-time opt imization process that depends primarily on sili ca/alumina ratio and hydroxide concentration of the system. The optimum conditions obtained in the present study were at 2.5N fused ash at 60 OC and with reaction time of 24 hours, the maximum yield obtained in this case was 38.4 % zeolite A. Zeolite A yield can be increased to more than 38.4 % since significant amount s of non-reacted sodium aluminates

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128 silicate gel was still present in the reaction system as observed by SEM. This can be verified by continuously adjusting silica /alumina ratio is continuously adjusted during the reaction time which was not within the scope of the present study. However, the present suggested interaction model indicates that it is possible to establish a relationship between the factors that affect zeolite A formation.

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129 CHAPTER 6 CONCLUSIONS This chapter summarizes the findi ngs and discusses the importance and implications of the results obtained in this dissertation. Both scientific and engineering aspects of these findings will be concluded. 6.1 Hydrothermal Treat ment of MSW Ash Hydrothermal treatment of MSW was foun d to be in general inefficient in producing significant amounts (<14%) of zeolites. Consequently, the produced zeolitic materials were characterized by low cation exchange abilities (<75 meq/100g) and with no commercial value. The following is a summary of the results and the conclusions that can be made on zeolite syn thesis using only hydrothermal treatment: Hydrothermal treatment of the ash was inefficient in dissolving the refractory fractions of ash particl es which included quartz, glass and porcelain and the process di d not succeed in extracting enough silica and alumina to form si gnificant amounts of zeolite. Zeolite formation was less than 14 %.

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130 The presence of calcium carbonates (calcite) and nitrate as well as using high temperature, 100 0C and high silica/alumina ratio have affected zeolite formation by directing the reaction toward forming sodalite structure which resulted in the formation of unnamed zeolite types. Forming low density zeolites such as zeolite X and A could not be accomplished by applying hydrothermal treatment. Zeolite P1 was formed as silica/alumina ratio was reduced from 13.9 to 2.5 which implic ates that alumina cont ent in the original ash was low below that required to form such zeolite and as alumina was added. In conclusion, treating the ash by hydrothermal process was not efficient in synthesizing low densit y zeolites, namely zeolite A and X, which are of interest for this particular study due to their wide industrial and environm ental applications. 6.2 Fusing MSW Ash Prior to Hydrothermal Treatment Fusing MSW ash prior to hydrothe rmal treatment has dramatically changed both physical and chemical properti es of the ash and resulted in the formation of sodium alumina silicates and s odium silicates precursors to zeolites A an X formation. Both amounts and the cation exchange capacity of the ash were increased significantly. Following is a summary of the conclusions on zeolite synthesis by fusion prior to hydrothermal treatment.

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131 Fusion at 1.5N has slightly improved the CEC values of the ash where the CEC values have increased from 17.0 meq/100g for non-treated ash up to 164 meq/100g for the treated ash. This is due to the formation of higher amounts of unmanned zeolite and z eolite P1 as well as formi ng the new zeolites phases zeolite X and zeolit e A. In general, the increase in the CEC value for fused ash was almost 55% higher than that obtained when the ash was treated hydrothermally indicating that fusion has activated the ash particles. Following is a summary of the results and the conc lusions that can be made on zeolite synthesis at 1.5N: Fusing the ash at 1.5N did activa te the ash but not significantly and that was true regardless of tem peratures used in this study. The major contribution to the CEC value came from forming unnamed zeolites. Both zeolites X and P1 were form ed at silica/alumina ratio of 13.9, while zeolite A was formed at silic a/alumina ratio of 2.5. These results implicate the importance of controlling silica/aluminum ratio to produce certain type of zeolite. Fusion at 1.5N did not fully activate the ash particles which results in the precipitation of the excess al umina as aluminum hydroxide. The maximum CEC value obtained in this case was 164 mequ/100g which is below the values (240-400 meq/100g) of commercial zeolite materials available in the market.

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132 Same trend of zeolite types formed at 1.5N fusion was observed to form at 2.5N fusion, expect that zeolite X did not form at 2.5N and new zeolite phases including sodalite appeared at 1000C and Zk-14 appeared at 1000C and at 600C. In general, it was found that fusion at 2. 5N dramatically incr eased the amounts of zeolites A formation regardless of temper ature used. Following is summary of the conclusions on zeolite synthesis at 2.5N. The lack of formation of non zeo lites phases including katoite, gibbsite and bayerite indicates that fusing the ash at 2.5N has actually increased the amounts of ac tive silica which resulted in its reaction with all the aluminum in the system to form zeolites. The formation of sodium alumina silicate gel and sodium silicates is believed to be of major cont ribution in triggering zeolite A formation and X. Zeolite A was again produced at 600C in higher amounts than it did at 1000C. The formation of sodalite at 100oC at 2.5N indicates that at temperature used and as hydroxide concentration increased from 1.5N to 2.5N, zeolite A was eit her dissoluted or transformed into sodalite structure. Both the increase in hydrox ide concentration and temperature resulted in attacking the Al-O-Al bri dges in zeolite A nuclei causing their transformation into sodalite or unnamed zeolite.

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133 The competition between zeolit e A and sodalite formation is probably due to the pr esence of carbonates and nitrates which affected zeolite synthesis process by directing the reaction toward forming sodalite structure zeolites. The maximum CEC value obtained for 2.5N fused ash was as 237.4 meq/100g and total zeolites of 45.33 % and which was obtained at 600C for 24 hours. Same zeolite types formed at 2.5N were observed at 3.5N with the exception that both zeolites P1 and Zk-14 did not form in this case and zeolite A disappeared at 72 hours when fu sed ash was treated at 100oC. In general, it was found that zeolite A formati on was slightly reduced as hydroxide concentration was increased from 2.5N to 3.5N. The following is a summary of the results and the conclusions that can be made on zeolite synthesis at 3.5N: Increasing sodium hydroxide concen tration from 2.5N to 3.5N at 100oC resulted in reduction in ze olite A formation and increased the percentages of formation of soda lite and unnamed z eolites. This confirms the theory of hydroxi de attack on zeolite A nuclei. Though zeolite A formation was slight ly reduced at 3.5N fusion, still it was possible to increase the CE C value of the total ash up to 245.4 meq/100g, which is within the commercial range.

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134 Zeolite A maximum va lues were always at 24 hours when treating the ash at 600C while the maximum values were obtained at 6 hours when treating the ash at 1000C. This was found to be true regardless of what hydroxide concentration was used. The reduction in time for zeolite A formation as the temperature increases is due to the rapid formati on of zeolite nuclei at higher temperature. In this case the cryst al sizes were smaller than that obtained at 600C at 24 hours due to the increase in the rate of formation in shorter time. 6.3 Factors and Mechanism of Z eolite A Formation from MSW Conclusions on the factors that affected zeolite A formation as well as the mechanism of formation can be summarized as follows: Zeolite A precursors: It was found that the formation of sodium silicates and sodium aluminum silicate which acts as precursors to zeolite A formation is of importanc e to the synthesis of zeolite A from MSW. Silica/alumina ratio: Silica/alumina ratio of MSW ash used in this particular study was higher than that required to produce zeolite A, and as this ratio was reduced to the ratio, 2.5, that is within the range of forming such zeolite type. Hydroxide concentration: It is important to optimize hydroxide concentration in the reaction solu tion when synthesizing zeolite A

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135 from MSW since low hydroxide c oncentrations may results in low dissolution of silica needed to complete the reaction and high hydroxide concentrations may result s in attacking zeolite A nuclei and causes their dissolution or transformation into sodalite or zeolite P1. Temperature: zeolite A synthesis is preferable at low temperatures where it was found that syn thesizing zeolite at 600C results in producing higher amounts and larger crystal size s of zeolite A than that obtained at 1000C. Lower temperatures are preferable because zeolite A structure is more stable when formed at low temperatures and also zeolite A dissolution and tr ansformation into other zeolites phases and dissolution are most likely to occur at high temperatures. Reaction time: The time required for zeolite A to form depends greatly on temperature. The optimum results for zeolite A formation in this particular study was obtained at 6 hours when the temperature was set at 1000C while zeolite A optimum formation was at 24 hours when temperature was set at 600C. So it can be concluded that as the reaction temperature increases time should be reduced to prevent zeolite A di ssolution or transformation into another phase.

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136 There are two possible theories for zeolite A formation in the present study. First, it could be that zeolite A nuclei formation was triggered by the formation of D4R sub unit in the soluti on first through the interaction between added aluminates and the formed sodium s ilicate. Consequently, these subunits reacted with sodalite cages t hat were formed in the gel phase to build zeolite A structure. The second theory is that zeolite A nuc lei were formed solely in solution as sodium silicates reac ted spontaneously with the ad ded aluminates to form the nuclei of zeolite A, then t he nuclei continue their growth by consuming nutrients from the gel phase or the solution phase. It was not possible to know for sure which path was taken for zeolite A to form. The following conclusions can be made on zeolite A synthesis from MSW ash: The formation of sodium silicate within the gel and the addition of sodium aluminates were key factor s for initiating nuclei for zeolite A to form. The mechanism of zeolite A formation is considered as solution transport mediated process that in volved both gel and solution interaction rather than being pure solution reaction or pure gel transformation process. Solution super saturation and opt imum silica/alumina ratio were the driving force for nucleation of zeolite A.

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137 It seems that the presence of carbonate and nitrate negatively affected zeolite A formation by direct ing the reaction toward forming sodalite structure. 6.4 Experimental Design Analysis and M odeling of Zeolite A Formation The experimental design analysis performed to examine zeolite A formation under different used conditions was successful in establishing the relationship between the used condition s, namely hydroxide concentration, temperature and time. However, it should be taken in consideration that this model has constrains and it mostly present a simple pr imary model that aimed to establish and explore a possible trend fo r zeolite A formation from MSW, this model is not an actual gener al model that can be used practically to calculate zeolite A yield in any synthesis process. The reason for the restrictions in us ing such model is because of the complexity associated zeolite A formati on process due to the presence of many factors that affect the synthesis proce ss. For example, silica/alumina ratio and nutrients concentrations are two important factors that should be included in any model used to predict an actual production of zeolite A from a specific synthesis process. Silica/alumina ratio was fixed at 2.5 in the pr esent study and therefore it could not be included as a variable in the model. Also, nutrients concentrations were not adjusted during the study and they were fixed to that originally present in the reaction systems and therefore t hey were not variables as well.

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138 CHAPTER 7 RECOMMENDATIONS This dissertation showed that there is a potential to produce zeolite materials of commercial values using MSW ash as a source of silica and alumina. This work could provide an important altern ative to MSW ash disposal in landfills because it is not only directing the ash aw ay from environmentally unsafe disposal in landfills, but it also pr oduces a material that can be used as adsorbents for environmental purposes. The present work sets the bases and fundamentals of zeolite synthesis from MSW ash. By conducing more res earch work based on the finding of the present study to improve and better underst and zeolite formation from MSW, it will be possible to introduce such zeolitic materials to the ma rket for commercial uses as adsorbents. Following is a summar y of possible further work that can contribute to and enhance zeolites fo rmation from MSW ash and provide more understanding to the mechanisms of fo rmation of different zeolite types. Since MSW ash may have variation in its chemical compositions depending on MSW collection syst em and incineration conditions, it is important to apply the conditions used in the pres ent study to investigate and compare zeolites formation using different ash com positions from differ ent incinerators.

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139 It is expected that zeolite formation s hould be achieved even at different ash compositions as long as the right silica/alumina ratio is being adjusted. In the present work, silica/alumina ratio of the ash was 13.9. At this ratio, zeolite X struggled to form because this rati o is higher than that required for such zeolite to form. As silica/ alumina rati o was reduced to 2.5, zeolite A was formed and still zeolite X did not form because this ratio is lower than that required for zeolite X to form. Consequently, it is hypot hesized that if silica/alumina ratio is reduced from 13.9 to the range of 3.5 to 6, this could result in producing zeolite X. Therefore, it is recommended to vary silica/alumina ratio to other ratios different than what was used in the presen t work to study the effect of such variation on the formation of different zeolite types. The outcome of such variation will be an essential factor in controlling and engineer ing certain zeolite formation process. It is also important to explore the possibi lity of adjusting silica/alumina ratio by using alumina that was obtai ned from waste sources instead of using pure chemical compounds in order to reduce the cost of zeolite synthesis process as well as avoid the disposal of alumina waste in landfills. An example of alumina waste source is the spend that produces as a result of extracting alumina from its natural rock source, bauxite ore, through a process known as Bayer bypass process. Zeolites usually form during alumina extraction process due to the presence of impurities of silicates in alumina ore materials which react with alumina to form zeolite, which causes pr oblems during the extraction process. So

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140 it will be of interest to use such al umina waste instead of consuming pure chemical compounds. It was noticed that during z eolite A synthesis signifi cant amounts of the gel that was formed during fusion was still pres ent in the ash and zeolite A crystals were imbedded between its pores. This indicates that theor etically it is possible to increase the amounts of zeolite A formation if more alumina is added subsequently to the reaction system to adjus t silica/alumina rati o, the thing that will allow the reaction to continue between the ge l and the added alumina by keeping silica/alumina ratio in the level th at is suitable to synthesize zeolite A, this may results in producing zeolites A at amounts higher th an what has been achieved in the present study. Zeolite A synthesis from MSW is an optimization process that depends on the interaction between solution hydr oxide concentration, crystallization temperature and reaction time. In the presen t work, it was found that using lower crystallization temperature, 600C, produces higher amounts of zeolite A than at higher temperatures, 1000C, but it also requires that reaction time should be increased to allow larger crystal growth the time has to be increased from 6 hours to 24 hour. It is expected that if the temperat ure is set up some where between 600C and 1000C reaction time to produc e zeolite may be reduced. Further work should be performed where different reaction per iods and temperatures should be investigated to find the optimum c onditions for zeolite A formation.

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141 Zeolite A formation was achieved at 2. 5N sodium hydroxide concentration in higher amounts than that obtained at 3.5N. The amou nts of produced zeolites were reduced slightly at 3.5N due to hydroxide attack on zeolite A nuclei. It is expected that in the range of 2.5N and 3.5N, probably at 3N, zeolite A can be produced at higher amounts than that obtained at 2.5N, this because more silica will be available for reacti on but less hydroxide attack wil l influence the reaction, which will results in increasing the am ounts of zeolite A formation. So further research should be conducted to investi gate the effect of changing hydroxide concentration on stability and amount s of zeolite A formation.

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142 REFERENCES Antonic, T. and Subotic, B., 1997. In fluence of gel properties on the crystallization of zeolites: part 1: Influence of alkalinity during gel preparation on the kinetic of nucleation of zeolite A. Zeolites, 18:291-300. Armstrong, J. A. and Dann, S. E., 2000. Inve stigation of zeolite scales formed in Bayer Process. Microporous and Mesoporous Materials, 41:89-97. Barrer, R. M., 1982. Hydrothe rmal chemistry of zeolite. Acedemic press, London. Berkguat, V. and Singer, A., 1996. Hi gh capacity cation exchanger by hydrothermal zeolitization of coal fly ash. Appli ed Clay Science, 10:369378. Budd, P. M., Myatt, G. J., and Price, C., 1994. An empirical model for the nucleation and growth of zeo lites. Zeolites, 14: 198-202. Catalfamo, P., Pasquale, S. D., Corigli ano, F. and Mavilia, L., 1997. Influence of calcium content on coal fly ash features in some innovative applications. Resources Conservation and Recycling, 20:119-125. Chang, H. and Shih, W., 1998. A general met hod for the conversion of fly ash into zeolites as ion exchangers for cesium. Industrial Engineering Chemical Resources, 37:71-78. Cundy, C. S. and Cox, P. A., 2003. The hydrothermal synthesis of zeolites: History and development from the ear liest days to the present time. Chemical Review, 103:663-701. Davis, M. E. and Lobo, R. F., 1992. Zeolite and molecular sieve synthesis. Chemical materials, 4:756-768. Dayer, A., 1988. An introduction to zeolite molecular sieves. Bath Press Ltd, UK. Dutta, P. K. and Bronic, J., 1994. Mechani sm of zeolite formation: Seed-gel interaction. Zeolites, 14:250-255.

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143 Grujic, E., Subotic, B. and De spotovic, A, 1989. Transforma tion of zeolite A into hydroxysodalite. III. The influence of temperature on the kinetic of transformation. Zeolites: facts, figures, future. Elsevier Science Publishers B. V., Amsterdam. Juan, R., Hernandez, S., Querol, X, Andres J. and Moreno, N ., 2002. Zeolitic materials synthesized from fly ash: use as cationic exchanger. Journal of Chemical Technology and Biotechnology, 77:299-304. Kargbo, D., 2003. A new method to synthes ize zeolites from municipal solid waste combustion ash. Proceedings of the 18th International Conference on Solid Waste Technology and Management, Philadelphia. Kostinko, J., 1983. Factors influencing the synthesis of zeolites A, X and Y. Intrazeolite Chemistry, American Chemical Society. Kostinko, J., 1983. Factors influencing t he synthesis of zeolites A, X and Y. Symposium on Advances in Zeol ite Chemistry, Am erican Chemical Society. Krznaric, I., Antonic, T. and Subot ic, B., 1997. Physical chemistry of aluminosillicate gels. Part 1: infl uence of batch concentration on chemical composition of the gel s. Zeolites, 19:19-29. Krznaric, I., Antonic, T. and Subot ic, B., 1998. Physical chemistry of aluminosillicate gels. Part 2: influence of batch molar Sio2/Al2O3 on chemical composition of the gels. Microporous and Mesoporous Materials, 20:161-175. Krznaric, I. and Subotic, B., 199p. Physical chemistry of aluminosillicate gels. Part 3: influence of batch alkalinity on the chemical composition of the gels. Microporous and Mesopor ous Materials, 28:415-425. Krznaric, I., Antonic, T., Bronic, J., Subotic, B. and Thompson, R. W., 2003. Influence of silica sources on chemic al composition of aluminosillicate hydrogels and the results of their hydrothermal treatment. Croatica Chemica ACTA, 76(1):7-17. Lin, C. F. and Hsi, H. C., 1995. Resource recovery of waste fly ash: Synthesis of zeolite-like materials. Environmen tal Science Technology, 29:1109-1117. Marui, Y., Irie, R., Takiyama, H., Uchida H. and Matsuoka, M., 2002. Analysis of nucleation of zeolite A from clear so lutions. Journal of Crystal Growth, 237-239:2148-2152.

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144 Ma, W., Brown, P. W. and Komarneni, S., 1998. Characterization and cation exchange properties of zeo lite synthesized from fly ash. Journal of Materials Research, 13:3-7. Miyake, M., Tamura, C., and Matsuda, M., 2002. Resource recovery of waste incineration fly ash: Synthesis of z eolites A and P. Journal of American Ceramic Society, 85:1873-1875. Molina, A. and Poole, C., 2004. A compar ative study using two methods to produce zeolites from fly ash. Minerals Engineering, 17:167-173. Murayama, N., Tanabe, M., Yamamoto, H. and Shibata, J., 2002. Mechanism of zeolite synthesis from coal fly as h by alkali hydrothermal reaction. International Journal of Mi neral Processing, 64: 1-17. Murayama, N., Tanabe, M., Yamamoto, H. and Shibata, J., 2003. Reaction, mechanism and application of various ze olite syntheses from coal fly ash. Materials transactions, 44(12):2475-2480. Murayama, N., Yamamoto, H. and Shibata, J., 2002. Zeolite synthesis from coal fly ash by hydrothermal reaction usi ng various alkali sources. Journal of Chemical Technology and Biotechnology, 77:280-286. Nikolakis, V., Vlacho, D. G. and Tsapat sis, M., 1998. Mode ling of zeolite crystallization: the ro le of gel microstructure. Microporous and Mesoporous Materials, 21:337-346. Penilla, R. P., Bustos, G. and Elizalde, G., 2003. Zeolite synthesized by alkaline hydrothermal treatment of bottom ash fr om combustion of municipal solid wastes. Journal of American Ceramic Society, 86:1527-1533. Querol, X., Alastuey, A., Soler, A. and Plana, F., 1997. A fast method for recycling fly ash. Microwave-Assist ed zeolite synthesis. Environmental Science Technology, 37:2527-2533. Scott, J., Guang, D., Naeramitmarnsuk K., Thabuot, M. and Amal, R., 2001. Zeolite synthesis from coal fly ash for the removal of lead ions from aqueous solution. Journal of Chemical Technol ogy and Biotechnology, 77:63-69. Sheikh, A. Y. and Jones, A. G.,1996. Popul ation balance modeling of particles formation during the chemical synthesis of zeolite crystals: Assessment of hydrothermal precipitation ki netics. Zeolites, 16:164-172.

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145 Shigemoto, N., Sugiyama, S., Hayashi, H .,1995. Characterization of Na-X, Na-A, and coal fly ash zeolites and their amorphous precursors by IR, MAS and XPS. Journal of Materials Science, 30:5777-5783. Shih, W. and Chang, H.,1996. Conversion of fly ash into zeolites for ionexchange applications. Mate rials Letters, 28:263-268. Singer, A. and Berkgaut, V. ,1995. Cation exchange properti es of hydrothermally treated coal fly ash. Environment al Science Technology, 29:1748-1753. Stamboliev, C., Scpova, N., Bergk, K. and Porsch, M., 1985. Synthesis of zeolite A and P from natural waste material s. Zeolites, Elsevier Science Publishers B. V., Amsterdam. Steenbruggen, G. and Hollman, G. G.,1998. The synthesis of zeolites from fly ash and the properties of the zeolite products. Journal of Geochemical Exploration, 62:305-309. Subotic, B., Masic, N. and Smit, I.,1985. Anal ysis of particulate processes during the transformation of zeolite A into hydroxysodalite. Zeolites, Elsevier Science Publishers B. V., Amsterdam. Tanaka, H., Furusawa, S. and Hino, R., 2002. Synthesis, characterization and formation process of Na-X zeolite from coal fly ash. Journal of Materials Synthesis and Proces sing, 10(3):143-148. Tanaka, H. Matsumaura, S. and Hino, R., 2004. Froamtion process of Nazeolites from coal fly ash. Journal of Materials Science, 39:1677-1682. Tanaka, H., Matsumaura, S., Furusawa, S. and Hino, R., 2003. Conversion of coal ash to Na-X zeolites. Journal of Materials Science Letters, 22:323325. Tanaka, H., Sakai, Y. and Hin o, R., 2002. Formation of Na-A and -X zeolites from waste solutions in conversion of c oal fly ash to zeolites. Materials Research Bulletin, 37:1873-1884. Tannous, M. K., Helmy, M., K halil, F. H. and Abadir, M. F., 1985. Optimi zation of faujasite synthesis using factorial design analysis. Zeolites, Elsevier Science Publishers B. V., Amsterdam. Traa, Y. and Thompson, R. W., 2002. Controlled co-crysta llization of zeolites A and X. Journal of Materials Chemistry, 12:496-499. Yang, G. and Yang, T., 1998. Synthesis of z eolites from municipal incinerator fly ash. Journal of Hazardous Materials, 62: 75-89.

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146 APPENDICES

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147 Appendix A: X-Ray Diffraction Parameters X-Ray diffraction analysis was perform ed using Phillips X'Pert Powder XRay Diffraction, XRD. 1. Samples Preparations The samples were grinded by mortar to pass through 200 micrometer sieve. A total sample of 0.6 grams of as h that contains 5% internal standard titanium oxide was then placed on al umina holder and examined by XRD. 2. X-ray Diffraction Operating Conditions Comment Exported by X'Pert SW Raw Data Origin PHIL IPS-binary (scan) (.RD) Scan Axis Gonio Start Position [Th.] 2.0250 End Position [Th.] 59.9750 Step Size [Th.] 0.0500 Scan Step Time [s] 10.0000 Scan Type CONTINUOUS Offset [Th.] 0.0000 Divergence Slit Type Fixed Divergence Slit Size [] 1.0000 Specimen Length [mm] 10.00 Receiving Slit Size [mm] 0.2000 Measurement Temperature [C] 0.00 Anode Material Cu Generator Settings 45 kV, 40 mA Diffractometer Type XPert MPD Diffractometer Number 1 Goniometer Radius [mm] 200.00 Dist. Focus-Diverg. Slit [mm] 91.00 Incident Beam Monochromator No Spinning No

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148 Appendix B: Scanning Electron Microscopy Samples were observed by Scanning Electron Microscopy, SEM, using HITACHI 3500 SEM. 1. Samples Preparation The samples were tested in the powder form. Non-treated and treated ash samples were placed on alumina stubs and coated with gold for 10-15 minutes. The samples were then placed in the SEM champers and zeolite images were observed at high vacuum. 2. Instrument operating Parameters: Data Size=1280x960. Accelerating Voltage= 15000. Sub Signal Name=SE.. Vacuum= High. Working distance = variable. Filament = tungsten.

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Table C.1 Chemical composition of different ash fraction. Ash Fraction Al % Ca % Cu % Fe % K % Mn % Mg % Si % Na % Ti % Zn % Pb % Original ash sample (combined ) 4.160 8.943 0.0684.528 0.5090.0370. 60831.415 4.030 4.030 0.3962.142 25 mm 5.203 5.043 2.3550.675 0.0150.0060. 45930.578 1.060 1.060 0.0450.000 19 mm 4.019 8.858 4.6958.208 0.0000.0280. 54337.896 0.181 0.181 0.1080.028 9.5 mm 2.972 8.547 4.5304.613 0.0000.0280. 54344.575 1.138 1.138 0.1750.195 4. 75 mm 2.094 6.792 3.6002.689 0.0000.0170. 58629.123 1.251 1.251 0.2770.048 2.36 mm 3.340 7.302 3.8706.000 0.0000.0370. 81224.057 0.988 0.988 0.6880.113 1.18 mm 8.802 9.170 4.8607.019 0.0000.1670. 37435.123 0.778 0.778 0.8040.201 600 m 10.332 10.4560.47410.612 0.0000.118 0.81819.263 0.423 0.423 0.8560.311 212 m 6.283 7.104 3.7654.557 0.0000.0540. 52938.349 0.286 0.286 0.5830.308 75 m 6.425 10.5005.5655.745 0.0000.0910. 74719.472 0.184 0.184 0.8180.289 Pan < 75m 9.679 15.3968.1607.019 0.0000.1561. 21135.321 0.323 0.323 1.2540.348Appendix C: Chemical Composition of Different Ash Fractions 149

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150 Appendix D: Statistical Analysis on Fused Ash Table D.1 Statistical analysis for fused ash at 1.5N at 100 oC for 6 hours. Silica/alumina ratio is 2.5. Ash Content Quatrz Calcite Gibbsite Bayerite Unnamed zeolite Zeolite A Trial 1 1.767 1.051 1.114 1.231 0.331 0.073 Trial 2 1.262 0.974 1.369 0.557 0.592 0.181 Trial 3 1.219 0.914 1.138 0.776 0.809 0.000 Average 1.416 0.979 1.207 0.855 0.578 0.085 Standard Deviation 0.249 0.056 0.115 0.280 0.195 0.074 Variance 0.062 0.003 0.013 0.079 0.038 0.006 % 27.653 19.130 23.582 16.694 11.282 1.658 % (Of total Zeolites content only) 87.188 12.812

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151 Appendix D: (Continued) Table D. 2 Statistical analysis for fused ash at 1.5N at 100 oC for 24 hours. Silica/alumina ratio is 2.5. Ash Content Quatrz Calcite Gibbsite Bayerite Unnamed zeolite Trial 1 1.858 0.896 1.148 0.813 0.700 Trial 2 0.570 0.915 0.882 0.699 0.647 Trial 3 2.239 1.070 1.012 0.688 0.700 Average 1.556 0.960 1.014 0.733 0.682 Standard Deviation 0.714 0.078 0.108 0.057 0.025 Variance 0.510 0.006 0.012 0.003 0.001 % 31.453 19.418 20.504 14.827 13.798 % (Of total Zeolites content only) 100.000

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152 Appendix D: (Continued) Table D.3 Statistical analysis for fused ash at 1.5N at 60 oC for 6 hours. Silica/alumina ratio is 2.5. Ash Content Quatrz Calcite Gibbsite Bayerite Unnamed zeolite Zeolite A Trial 1 1.078 0.644 0.360 0.601 0.752 0.207 Trial 2 0.530 0.636 0.665 0.721 0.729 0.000 Trial 3 0.839 0.618 0.227 0.398 0.846 0.095 Average 0.815 0.633 0.417 0.573 0.775 0.101 Standard Deviation 0.224 0.010 0.183 0.133 0.050 0.085 Variance 0.050 0.000 0.034 0.018 0.003 0.007 % 24.600 19.083 12.594 17.294 23.396 3.033 % (Of total Zeolites content only) 88.525 11.475

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153 Appendix D: (Continued) Table D.4 Statistical analysis for fused ash at 1.5N at 60 oC for 24 hours. Silica/alumina ratio is 2.5. Trial 1 1.450 0.974 0.837 0.667 0.987 0.241 Trial 2 2.381 1.129 0.971 1.078 1.050 0.516 Trial 3 0.458 1.053 0.868 0.955 0.811 0.240 Average 1.430 1.052 0.892 0.900 0.949 0.332 Standard Deviation 0.785 0.063 0.057 0.172 0.101 0.130 Variance 0.617 0.004 0.003 0.030 0.010 0.017 % 25.738 18.943 16.056 16.198 17.085 5.982 % (Of total Zeolites content only) 74.067 25.933

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154 Appendix D: (Continued) Table D.5 Statistical analysis for fused ash at 2.5N at 100 oC for 6 hours. Silica/alumina ratio is 2.5. Ash Content Quatrz Calcite Zeolite ZK-14 Zeolite A Trial 1 0.922 1.806 0.675 0.625 Trial 2 0.680 1.323 0.580 0.404 Trial 3 0.610 1.320 0.681 0.437 Average 0.737 1.483 0.645 0.488 Standard Deviation 0.134 0.228 0.046 0.097 Variance 0.018 0.052 0.002 0.009 % 21.987 44.212 19.238 14.564 % (Of total Zeolites content only) 56.913 43.087

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155 Appendix D: (Continued) Table D.6 Statistical analysis for fused ash at 2.5N at 100 oC for 24 hours. Silica/alumina ratio is 2.5. Ash Content Quatrz Calcite Unnamed zeolite Zeolite A Trial 1 0.879 1.537 1.068 0.356 Trial 2 0.606 1.258 1.148 0.242 Trial 3 0.746 2.044 0.689 0.303 Average 0.744 1.613 0.968 0.300 Standard Deviation 0.111 0.325 0.200 0.046 Variance 0.012 0.106 0.040 0.002 % 20.512 44.488 26.713 8.287 %( Of total Zeolites content only) 76.322 23.678

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156 Appendix D: (Continued) Table D.7 Statistical analysis for fused ash at 2.5N at 60 oC for 6 hours. Silica/alumina ratio is 2.5. Ash Content Quatrz Calcite Unnamed zeolite Zeolite A Trial 1 1.252 0.711 1.088 0.350 Trial 2 0.898 0.630 1.659 0.624 Trial 3 0.522 0.707 1.085 0.299 Average 0.891 0.683 1.277 0.424 Standard Deviation 0.298 0.037 0.269 0.142 Variance 0.089 0.001 0.073 0.020 % 27.197 20.850 39.001 12.952 % (Of total Zeolites content only) 75.070 24.930

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157 Appendix D: (Continued) Table D.8 Statistical analysis for fused ash at 2.5N at 60 oC for 24 hours. Silica/alumina ratio is 2.5. Ash Content Quatrz Calcite Zeolite ZK-14 Zeolite A Trial 1 0.939 1.536 0.262 0.704 Trial 2 2.217 2.217 0.676 0.946 Trial 3 0.683 1.560 0.725 0.725 Average 1.280 1.771 0.554 0.792 Standard Deviation 0.671 0.316 0.208 0.110 Variance 0.450 0.100 0.043 0.012 % 29.105 40.281 12.607 18.007 % (Of total Zeolites content only) 41.180 58.820

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158 Appendix D: (Continued) Table D.9 Statistical analysis for fused ash at 3.5N at 100 oC for 6 hours. Silica/alumina ratio is 2.5. Ash Content Quatrz Calcite Unnamed zeolite Zeolite A Trial 1 0.756 1.111 1.069 0.288 Trial 2 0.000 1.391 0.945 0.414 Trial 3 0.238 1.222 1.145 0.345 Average 0.331 1.241 1.053 0.349 Standard Deviation 0.316 0.115 0.083 0.052 Variance 0.100 0.013 0.007 0.003 % 11.137 41.730 35.403 11.730 % (Of total Zeolites content only) 75.112 24.888

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159 Appendix D: (Continued) Table D.10 Statistical analysis for fused ash at 3.5N at 100 oC for 24 hours. Silica/alumina ratio is 2.5. Ash Content Quatrz Calcite Sodailte Zeolite A Trial 1 0.025 1.321 1.682 0.525 Trial 2 0.241 1.268 1.793 0.181 Trial 3 0.386 1.762 1.306 0.159 Average 0.217 1.450 1.594 0.288 Standard Deviation 0.148 0.222 0.208 0.168 Variance 0.022 0.049 0.043 0.028 % 6.120 40.855 44.900 8.125 % (Of total Zeolites content only) 84.678 15.322

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160 Appendix D: (Continued) Table D.11 Statistical analysis for fused ash at 3.5N at 60 oC for 6 hours. Silica/alumina ratio is 2.5. Ash Content Quatrz Calcite Unnamed zeolite Zeolite A Trial 1 0.293 1.008 1.250 0.248 Trial 2 0.115 1.042 0.976 0.383 Trial 3 0.134 1.044 2.095 0.000 Average 0.180 1.031 1.440 0.210 Standard Deviation 0.080 0.017 0.476 0.159 Variance 0.006 0.000 0.227 0.025 % 6.306 36.027 50.323 7.345 % (Of total Zeolites content only) 87.264 12.736

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161 Appendix D: (Continued) Table D.12 Statistical analysis for fused ash at 3.5N at 60 oC for 24 hours. Silica/alumina ratio is 2.5. Ash Content Quatrz Calcite Unnamed zeolite Zeolite A Trial 1 0.322 2.537 0.411 0.742 Trial 2 0.689 2.580 1.191 0.733 Trial 3 0.207 2.962 0.843 0.653 Average 0.406 2.693 0.815 0.709 Standard Deviation 0.206 0.191 0.319 0.040 Variance 0.042 0.036 0.102 0.002 % 8.779 58.249 17.627 15.346 % (Of total Zeolites content only) 53.459 46.541

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162 Appendix E: Linear Regression Analysis on Zeolite A Formation Summary output Regression Statistics Multiple R 0.929814439 R Square 0.86455489 Adjusted R Square 0.502020759 Standard Error 11.19606953 Observations 12 ANOVA df SS MS F Significance F Regression 7 4000.648735 571.5212479 4.5593319 0.080668278 Residual 5 626.759865 125.351973 Total 12 4627.4086 Coefficients Standard Error t Stat P-value Lower 95% Upper 95% Intercept 0 #N/A #N/A #N/A #N/A #N/A X Variable 1 -4.755024802 10.5035267 -0 .452707451 0.6697257 31.75519973 22.24515 X Variable 2 0.744178797 2.210639131 0. 336635132 0.7500613 4.938449997 6.4268076 X Variable 3 0.794682894 1.091399491 0.728132 0.4991886 2.010848811 3.6002146 X Variable 4 0.01086938 0.233273632 0. 046594978 0.9646398 0.588779581 0.6105183 X Variable 5 0.12075489 0.155138925 0. 778366165 0.4715631 0.278042412 0.5195522 X Variable 6 -0.01265562 0.027058258 -0 .467717462 0.6596636 0.082211086 0.0568998 X Variable 7 0.007671281 0.013203624 0. 580998125 0.5864452 0.041612276 0.0262697

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163 Appendix E: (Continued) RESIDUAL OUTPUT Observation Predicted Y Residuals Standard Residuals 1 7.306269837 -4.016269837 -0.555728817 2 11.80297477 8.797025234 1.217239036 3 16.06238234 -8.202382344 -1.134958661 4 26.57839628 12.22160372 1.69109588 5 9.187328646 -7.207328646 -0.997273686 6 16.67312182 11.82687818 1.636477948 7 0.546411837 -0.546411837 -0.075606674 8 8.528191966 5.731808034 0.793106795 9 13.26233095 -4.562330951 -0.631286962 10 37.09441022 -5.214410222 -0.721514774 11 24.15891499 -5.358914994 -0.741509812 12 16.50997209 -3.859972094 -0.534101993

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164 Appendix F: Regression Analysis as a Function of Na The yield equation was tested for power a = 1, 2, 3 ., n. As the power a increases the resulted R squared were used to evaluate fitness of the proposed model. The ratios of R squared obtained in each case were used to determine the best fitness for the model. Table F.1 and Figure F.1 pres ent the resulted ratios for R2 a+1 / R2 a such that good fitness is obtai ned as the values of R2 a+1 / R2 a = 1. It was found that the best model fits with lo w residuals can be obtained at N6, and no much changes occurs as the power is further increased as shown in Table F.1 and Figure F.1. Table F.1 The resulted ratios for R squared values, R2 a+1 / R2 a, for adding Na to the proposed model. Power, Na R2 value R2 a+1 / R2 a N1 0.864 N2 0.91 1.05 N3 0.962 1.05 N4 0.98 1.02 N5 0.986 1.01 N6 0.987 1 N7 0.988 1 N8 0.988 1

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165 Appendix F: (Continued) 0.9 0.91 0.92 0.93 0.94 0.95 0.96 0.97 0.98 0.99 1 0246810 power Na R 2 Figure F.1 R2 values versus power increases for N in the proposed model. Further, it was found that zeolite A yield, Y, for fused ash at 3.5N at 100oC for 24 hours deviate from the general tr end observed as it showed high values relative to the other samples treated at same conditions. Therefore, the yield value in this case can be considered as outlier and it was omitted from regression analysis. As a result of omitti ng the outlier, the mo del R squared value increased from 0.98 to 0. 998 and the residuals were reduced significantly and the model showed better fit. Table F.2 pr esents the results of the regression analysis performed after excluding the ou tlier case, the table shows equation coefficients and statistical analysis perfo rmed on the model at 95% confidence. Table F.3 presents a comparison bet ween experimentally obtained yield values and the predicted yield values, Y, as calculated from the proposed model, the table shows the residuals as well. As shown in Table F.2 the model shows good fit for the predicted Y values. The fi nal format of the model is described here below Yi =0.946 -0.025 N6 + 2.44Nt + 2.85t -0.515 T +0.355 NT +0.037 Tt +0.031 NTt

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166 Appendix F: (Continued) Table F.2 The results of the final regression analysis showing equation coefficients and statistical analysis performed on the model at 95% confidence for N6. SUMMARY OUTPUT Regression Statistics Multiple R 0.996952644 R Square 0.993914574 Adjusted R Square 0.979715248 Standard Error 1.849945044 Observations 11 ANOVA Df SS MS F Regression 7 1676.860801 239.551543 69.99730483 Residual 3 10.26689 3.422296667 Total 10 1687.127691 Coefficients Standard Error t Stat P-value Intercept 0.94616921 4.42616 1691 0.21376743 0.844432627 X Variable 1 -0.02516928 0.001882456 13.37045045 0.000904389 X Variable 2 2.442014131 0.2609011 9.359922715 0.002582794 X Variable 3 2.848599047 0.602394236 4.728795328 0.017921477 X Variable 4 -0.51527608 0.082573972 6.240175517 0.008300782 X Variable 5 0.355356772 0.028711821 12.37667138 0.001136438 X Variable 6 0.037561023 0.008688859 4.322894887 0.02281526 X Variable 7 0.031071021 0.004036734 7.697069236 0.004557376

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167 Appendix F: (Continued) Table F.3 A comparison between experimentally obtained yield values, Y, and the predicted yield. values, Y, as calculated from the proposed model, the table shows the residuals. RESIDUAL OUTPUT EXPERIMENTAL OUTPUT Observation Predicted Y Residuals Standard Residuals Actual Y % prediction 1 3.3551695950.0651695950.0643169683.29 98.06 2 22.284943051.6849430481.66289861420.6 92.44 3 8.2456181970.385618197-0.38057308 7.86 95.32 4 37.574943051.2250569521.20902929738.8 96.74 5 1.8946104720.0853895280.0842723611.98 95.49 6 27.581609710.9183902860.90637481 28.5 96.67 7 0.2722923360.2722923360.2687298830 0.00 8 13.987707660.2722923360.26872988314.26 98.05 9 6.9498873581.7501126421.7272155838.7 74.82 10 32.639438760.8394387560.82845621831.8 97.43 11 19.003779811.003779814-0.99064717 18 94.72

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168 Appendix F: (Continued) RESIDUAL OUTPUT Observation Predicted Y Residuals 1 4.79902834 -1.50902834 -0.256804748 2 10.2018095 10.39819046 1.769552374 3 13.1560674 -5.29606742 -0.901278806 4 30.0528986 8.747101396 1.488571891 5 7.77570503 -5.79570503 -0.986306573 6 21.3366702 7.163329791 1.219047418 7 0.87148158 -0.87148158 -0.148307757 8 11.4100168 2.849983231 0.485006945 9 6.64254837 2.057451633 0.350134808 10 37.9876874 -6.18768741 -1.053013695 11 25.935593 -7.93559301 -1.350470306 12 12.9865096 -0.33650959 -0.057266823 SUMMARY OUTPUT For N2 Regression Statistics Multiple R 0.95382578 R Square 0.90978362 Adjusted R Square 0.60152397 Standard Error 9.10332332 Observations 12 ANOVA Df SS MS F Significance F Regression 7 4178.522596.9317 7.2031869 9 0.03754387 2 Residual 5 414.352582.8705 Total 12 4592.874

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169 Appendix F: (Continued) SUMMARY OUTPUT For N3 Regression Statistics Multiple R 0.98080177 R Square 0.96197211 Adjusted R Square 0.71633864 Standard Error 5.91028468 Observations 12 ANOVA Df SS MS F Significance F Regression 7 4418.217631.173818.068920.00702897 Residual 5 174.657334.93147 Total 12 4592.874 RESIDUAL OUTPUT Observation Predicted Y Residuals Standard Residuals 1 4.35525359 -1.06525 -0.27922 2 14.6452948 5.954705 1.560837 3 10.7984579 -2.93846 -0.77022 4 33.8791337 4.920866 1.289849 5 4.88222181 -2.90222 -0.76073 6 24.9900752 3.509925 0.920015 7 -0.8737008 0.873701 0.229013 8 15.4337719 -1.17377 -0.30767 9 4.12423827 4.575762 1.199391 10 36.1487118 -4.34871 -1.13988 11 24.286831 -6.28683 -1.64789 12 10.9301469 1.719853 0.450805

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170 Appendix F: (Continued) SUMMARY OUTPUT For N4 SUMMARY OUTPUT Regression Statistics Multiple R 0.990123 R Square 0.980343 Adjusted R Square 0.756754 Standard Error 4.249302 Observations 12 ANOVA Df SS MS F Significance F Regression 7 4502.591643.227335.6229 0.001912 Residual 5 90.2828418.05657 Total 12 4592.874 RESIDUAL OUTPUT Observation Predicted Y Residuals Standard Residuals 1 4.271675 -0.98168-0.3579 2 17.79507 2.8049351.022612 3 9.716089 -1.85609-0.67669 4 35.29822 3.5017821.276665 5 3.520191 -1.54019-0.56152 6 25.92457 2.5754320.938941 7 -1.63646 1.6364570.596613 8 17.40668 -3.14668-1.1472 9 5.211692 3.4883081.271753 10 34.77358 -2.97358-1.0841 11 22.22218 -4.22218-1.53931 12 10.34305 2.3069540.84106

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171 Appendix F: (Continued) SUMMARY OUTPUT For N5 Regression Statistics Multiple R 0.992889 R Square 0.985829 Adjusted R Square 0.768824 Standard Error 3.607934 Observations 12 ANOVA Df SS MS F Significance F Regression 7 4527.788646.826949.690230.000999 Residual 5 65.0859313.01719 Total 12 4592.874 RESIDUAL OUTPUT Observation Predicted Y Residuals Standard Residuals 1 4.223419 -0.93342 -0.4008 2 19.39821 1.201789 0.51603 3 9.297491 -1.43749 -0.61724 4 35.75875 3.041245 1.305866 5 2.997898 -1.0179 -0.43707 6 26.06517 2.434827 1.045479 7 -1.93654 1.936545 0.831524 8 18.23285 -3.97285 -1.70588 9 6.399065 2.300935 0.987987 10 34.04608 -2.24608 -0.96443 11 20.95851 -2.95851 -1.27034 12 10.2283 2.421698 1.039841

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172 Appendix G: Yatess Al gorithm Calculations Table G.1 Yatess algorithm analysis that was perf ormed to determine the coefficients of the yield equation for 1.5N and 2.5N. Yield 1 2 3 Divisor Estimated Coefficient 3.29 23.89 70.55 114.99 8 14.4 20.0 46.66 44.44 89.03 4 22.26 7.86 30.18 48.25 6.85 4 1.71 38.8 14.26 40.78 1.37 4 0.34 1.98 17.31 22.77 -26.11 4 -6.53 28.5 30.94 -15 -7.47 4 -1.87 0 26.52 13.63 -38.69 4 -9.67 14.26 14.26 12.26 -25.89 4 -6.47 Solid arrow means adding. Dashed arrows means subtracting. Doted arrows means divide. Table G.2 Yatess algorithm analysis that was perf ormed to determine the coefficients of the yield equation for 2.5N and 3.5N. Yield 1 2 3 Divisor Estimated Coefficient 20.6 29.3 99.9 173.31 8 21.63 8.7 70.6 73.41 -31.01 4 -7.75 38.8 46.5 -18.9 21.71 4 5.43 31.8 26.91 -12.1 13.79 4 3.45 28.8 -11.9 41.3 -26.5 4 -6.63 18 -7 -19.6 6.79 4 1.7 14.26 -10.5 4.9 -60.89 4 -15.22 12.65 -1.61 8.89 3.99 4 1 Solid arrow means adding. Dashed arrows means subtracting. Doted arrows means divide.

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ABOUT THE AUTHOR Maysson Sallam received her BS in Geology in 1989 from University of Yarmouk, Jordan. She received her first MS degree in industrial geology in 1994 from University of Yarmouk, Jordan and her second MS degree in Environmental Engineering in 2002 from University of South Florida, United States. During her PhD program at Univer sity of South Florida, she has authorized one publication in the Journal of Solid Waste Technology and Management, and one article in conference proceeding. Her research interests are in solid waste management and ash recycling technology.


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Zeolite synthesis from municipal solid waste ash using fusion and hydrothermal treatment
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ABSTRACT: This dissertation investigates the possibility of producing zeolites from municipal solid waste ash, MSW ash, by using hydrothermal treatment alone and by introducing fusion at 550 ¨C prior to hydrothermal treatment. The study was performed at different treatment conditions where silica/aluminum ratio of 13.9 and 2.5, hydroxide concentrations of 1.5N, 2.5N and 3.5N, temperatures at 100¨C and 60 ¨C and time at 6, 24 and 72 hours were the major variables used to study zeolites synthesis process. The possibility of forming zeolites A, P1 and X was of particular interest in the present study. Factors, mechanism and modeling of zeolite A were investigated thoroughly in the present study. Zeolite synthesis process was evaluated using X-Ray diffraction to study different formed zeolite types and their chemical composition as well as their percentages. Morphological and physical characteristics of the produced zeolitic materials were evaluated by scanning electron microscopy, S EM, and cation exchange capacity property, CEC.The findings indicate that hydrothermal process did not succeed in producing significant amounts of zeolites. Consequently, the CEC of the produced zeolitic materials were much below the available commercial zeolite materials.Fusing the ash prior to hydrothermal treatment successfully produced sodium aluminum silicates and sodium silicates precursors to zeolite A formation. Fusion followed by hydrothermal treatment yielded significant amounts of zeolite A, at maximum value of 38.8% with CEC up to 245.0 meq/100g, which is within the range of commercially available zeolites. Experimental design analysis performed on zeolite A synthesis showed that zeolite A formation was reproducible and equation of interaction between different used conditions was established. Mechanism of zeolite A formation was concluded to be solution transport mediated process that involved both gel and solution interaction rather than being pure solution reaction or pu re gel transformation process. Solution super saturation and optimum silica/aluminum ratio were the driving force for nucleation of zeolite A.
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