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Inorganic sorption in polymer modified bentonite clays

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Title:
Inorganic sorption in polymer modified bentonite clays
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English
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Nocon, Melody Schwartz
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University of South Florida
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Tampa, Fla
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Subjects / Keywords:
Leachate
GCL
Isotherm
Montmorillonite
Salt
Dissertations, Academic -- Environmental Engineering -- Masters -- USF
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bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )

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Abstract:
ABSTRACT: In 1986, geosynthetic clay liners (GCLs) were invented and successfully used as a replacement for the soil layer in composite lining systems. In some applications an additive (polymer) is mixed with the bentonite to increase performance, especially in those that have low concentrations of sodium bentonite (EPA 2001).Studies showing significant increases in hydraulic conductivity values for bentonite in the presence of high salt concentrations are frequently documented and there is a risk of early breakthrough due to performance failure of the GCL clay component. (Ashmawy et al, 2002). It has also been stated that sodium, potassium, calcium, and magnesium have such a high affinity for the clay's surface other chemical species have little chance of attenuation (EPA 2001). For these reasons, researching sorption in the presence of major salt cations and polymers gains great importance.Distribution coefficients were extrapolated from Linear, Freundlich and Langmuir sorption isotherms for sodium and calcium cations modeled from data collected from batch tests of sodium bentonite and various manufactured and custom mixed polymer modified bentonites. Surface characterization before and after calcium or sodium solution exposure of all tested media was accomplished by use of scanning electron microscopy and energy dispersive x-ray analysis.
Thesis:
Thesis (M.A.)--University of South Florida, 2006.
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Includes bibliographical references.
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by Melody Schwartz Nocon.
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Document formatted into pages; contains 131 pages.

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Inorganic Sorption in Polymer Modified Bentonite Clays by Melody Schwartz Nocon A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering Department of Civil and Environmental Engineering College of Engineering University of South Florida Co-Major Professor: Alaa Ashmawy, Ph.D. Co-Major Professor: Maya Trotz, Ph.D. Robert Carnahan, Ph.D. Date of Approval: May 19, 2006 Keywords: leachate, gcl, isotherm, montmorillonite, salt Copyright 2006, Melody Schwartz Nocon

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DEDICATION For my family.

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ACKNOWLEDGEMENTS I would like to thank both of my major co-professors, Dr. Alaa Ashmawy and Dr. Maya Trotz, for their enc ouragement and guidance througho ut the formulation of my thesis. I would also like to thank Dr. Robe rt Carnahan for volunteering to be on my committee. I hold a huge amount of gratitude for Dr. Malcolm Siegel at Sandia National Laboratories in Albuquerque, Ne w Mexico, for giving me such a valuable research experience. I am also grateful for the entire staff in Sandias Geoc hemistry Department for their inspirational ideas suggestions, and support. Many thanks to Julio Aguilar, Delfin Carreon, Aidee Cira, Nivedita Das, Joniqua Howard, Maged Mishriki, Brian Runkles, and a ll the rest of my colleagues that made my stay here at the University of South Florida unforgettable.

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i TABLE OF CONTENTS LIST OF TABLES.............................................................................................................iv LIST OF FIGURES...........................................................................................................vi ABSTRACT.....................................................................................................................xiv CHAPTER ONE: INTRODUCTION..................................................................................1 1.1 Significance ......................................................................................................1 1.2 Objective...........................................................................................................2 1.3 Scope of Work..................................................................................................2 CHAPTER TWO: THEORETICAL BACKGROUND......................................................3 2.1 Material Classification......................................................................................3 2.1.1 General Clay Classification................................................................3 2.1.2 Classification of Sodium Bentonite....................................................6 2.1.3 General Synthetic Water Soluble Polymer Classification...................7 2.1.3.1 Structure and Water Soluble Polymers................................7 2.1.3.2 Polyelectrolytes....................................................................7 2.1.3.3 Polymerization.....................................................................8 2.1.3.4 Polyacrylamide....................................................................9 2.2 Clay Dispersions.............................................................................................10 2.2.1 Colloids and Sols..............................................................................10 2.2.2 The Diffuse Double Layer................................................................10 2.2.2.1 Surface Complexation in the Stern Layer..........................13 2.2.2.2 Diffuse Ions in the Guoy-Chapman Layer.........................15 2.2.2.3 Polymer Interactions in the Diffuse Double Layer............15 2.2.3 Sol Destabilization.............................................................................17 2.2.3.1 Addition of Neutral Salts...................................................17 2.2.3.2 Addition of Polyelectrolytes..............................................18 2.3 Sorption Isotherms...........................................................................................18 2.3.1 Linear Isotherm................................................................................19 2.3.2 Freundlich Isotherm..........................................................................19 2.3.3 Langmuir Isotherm...........................................................................20 CHAPTER THREE: EXPERI MENTAL BACKGROUND.............................................21 3.1 Water Chemistry.............................................................................................21 3.2 Atomic Adsorption..........................................................................................22 3.2.1 Flame Atomic Absorption Spectrometry (FAAS).............................22 3.2.1.1 Source Instrumentation......................................................22

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ii 3.2.1.2 Flame..................................................................................23 3.2.1.3 Sample Introduction and Atomization...............................24 3.3 Scanning Electron Microscopy (SEM)............................................................25 3.3.1 Basic Instrumentation....................................................................25 3.3.1.1 Electron Optical Column...................................................26 3.3.1.2 Vacuum System.................................................................27 3.3.1.3 Electronics and Display System.........................................27 3.3.2 Operational Parameters.....................................................................29 3.3.2.1 Condenser Lens..................................................................29 3.3.2.2 Accelerating Voltage.........................................................29 3.3.2.3 Scan Speed.........................................................................29 3.3.2.4 Working Distance..............................................................30 3.3.2.5 Aperture Size and Alignment.............................................30 3.4 Energy Dispersive X-Ray (EDX) Analysis.....................................................30 CHAPTER FOUR: METHODOLOGY............................................................................34 4.1 Instrumentation................................................................................................34 4.1.1 Reverse Osmosis and Deionization Unit...........................................34 4.1.2 Glassware..........................................................................................34 4.1.3 Plastic Containers..............................................................................34 4.1.4 Mixer.................................................................................................35 4.1.5 Tube Rotator......................................................................................35 4.1.6 Sample Bottles for Preservation........................................................35 4.1.7 Syringes and Syringe Filters..............................................................35 4.1.8 Sample Containers for FAAS............................................................36 4.1.9 Pipettes and Pipette Tips...................................................................36 4.1.10 FAA Machine..................................................................................36 4.1.11 pH Electrode...................................................................................36 4.2 Testing Materials.............................................................................................36 4.3 Initial Media Preparation.................................................................................37 4.4 Desorption........................................................................................................38 4.5 Time to Equilibrium.........................................................................................38 4.6 Batch Sorption Tests........................................................................................40 4.6.1 Slurries...............................................................................................40 4.6.1.1 Bentonite and Bentofix Slurries.........................................40 4.6.1.2 HC or MA Bentonite Slurries............................................40 4.6.2 Spike Solutions.................................................................................41 4.6.3 Initial Concentration Spiking and Agitation.....................................41 4.6.4 Quality Control.................................................................................41 4.6.5 Sample Preparation...........................................................................42 4.6.5.1 Supernatant........................................................................42 4.6.5.2 Solid Media........................................................................42 4.7 Sample Analysis...............................................................................................42 4.7.1 Flame Atomic Adsorption (FAA).....................................................42 4.7.1.1 Sodium...............................................................................42

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iii 4.7.1.2 Calcium..............................................................................43 4.7.2 Scanning Electron Microscopy (SEM).............................................44 4.7.3 EDX Analysis...................................................................................44 CHAPTER FIVE: DATA ANAL YSIS AND DISCUSSION...........................................45 5.1 Sorption Experiments.......................................................................................45 5.1.1 Empirical Isotherm Calculations......................................................46 5.1.1.1 Linear.................................................................................46 5.1.1.2 Freundlich..........................................................................46 5.1.1.3 Langmuir............................................................................46 5.1.2 Distribution Coefficients...................................................................47 5.1.3 Sorption Isotherm Discussion............................................................48 5.2 SEM Pictures...................................................................................................50 5.3 EDX Analysis..................................................................................................51 CHAPTER SIX: CONCLUSI ONS AND RECOMMENDATIONS................................54 6.1 Summary..........................................................................................................54 6.2 Conclusions......................................................................................................54 6.3 Recommendations............................................................................................56 REFERENCES..................................................................................................................57 APPENDICES...................................................................................................................59 Appendix A: Results..............................................................................................60

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iv LIST OF TABLES Table 1.1: Leachate Properties.............................................................................................2 Table 4.1: Polymer Material Data......................................................................................37 Table 5.1: Sodium Sorption Test Results..........................................................................47 Table 5.2: Calcium Sorption Test Results.........................................................................48 Table A.1: Desorption Tests..............................................................................................60 Table A.2: Na + 500 ppm Kinetic Test...............................................................................63 Table A.3: Na + 50 ppm Kinetic Test.................................................................................65 Table A.4: 500 Ca 2+ ppm Kinetic Test..............................................................................67 Table A.5: Spike Calculations for Sodium Sorption Experiments....................................69 Table A.6: Spike Calculations for Calcium Sorption Experiments...................................69 Table A.7: Unexposed Bentonite Elemental Composition..............................................109 Table A.8: Unexposed Bentofix Elemental Composition................................................111 Table A.9: Unexposed Medium Ani onic Polymer Elemental Composition....................113 Table A.10: Unexposed High Cationic Polymer Elemental Composition......................115 Table A.11: Sodium Exposed Be ntonite Elemental Composition...................................117 Table A.12: Sodium Exposed Bentofix Elemental Composition....................................119 Table A.13: Sodium Exposed 3% Medi um Anionic Elemental Composition.................121 Table A.14: Sodium Exposed 3% Hi gh Cationic Elemental Composition.....................123 Table A.15: Calcium Exposed Bentonite Elemental Composition..................................125 Table A.16: Calcium Exposed Bentofix Elemental Composition...................................127

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v Table A.17: Calcium Exposed 3% Medi um Anionic Elemental Composition...............129 Table A.18: Calcium Exposed 3% Hi gh Cationic Elemental Composition....................131

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vi LIST OF FIGURES Figure 2.1 (a) Silica Tetrahedral Sheet (b) Alumina Octahedral Sheet...............................3 Figure 2.2: Interlayer Bonding Via Hydration/Dipole Attraction.......................................4 Figure 2.3: Synthesis Patterns for Clay Minerals................................................................5 Figure 2.4: The Semi-Basic Unit Layer of M ontmorillonite (a) Two Dimensional Representation with Charge Distri bution and Average Range of Thickness (b)Three Dimensional Represen tation Including the Interlayer.......................6 Figure 2.5: Polyacrylamide..................................................................................................9 Figure 2.6: A Stable Sol.....................................................................................................10 Figure 2.7: Precipitate Salts and Interlayer Cations...........................................................10 Figure 2.8: Process of Hydration for NaCl........................................................................11 Figure 2.9: (a) Picture of I onic Distribution Near the Surface of Clay (b) Ionic Concentration as a Function of Distance from the Clay Surface....................12 Figure 2.10: (a) The Diffuse Double Layer (b) Mo lecular View of the Diffuse Double Layer.............................................................................................................12 Figure 2.11: An Inner Sphere Surface Complex................................................................13 Figure 2.12: An Outer Sphere Complex............................................................................14 Figure 2.13: Inner and Oute r Sphere Complexation..........................................................14 Figure 2.14: Ions in the Ster n and Guoy-Chapman Layer.................................................15 Figure 2.15: The Process of Adsorption for an Uncharged Polymer Molecule at the Clay Surface..................................................................................................16 Figure 2.16: Destabilization and Coagulati on by Suppression of the Diffuse Double Layer..............................................................................................................17 Figure 2.17: Colloid Agglomera tion via Particle Bridging...............................................18

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vii Figure 2.18: A Typical Linear Isotherm............................................................................19 Figure 2.19: A Typical Freundlich Isotherm.....................................................................19 Figure 2.20: A Typical Langmuir Isotherm.......................................................................20 Figure 3.1: Calcium Carbonate Solubility Curve..............................................................21 Figure 3.2: The Hollow-Cathode Lamp.............................................................................22 Figure 3.3: A Premixed Flame...........................................................................................23 Figure 3.4: Concentric Nebulizer System for a Premixed Burner.....................................24 Figure 3.5: SEM Surface Interactions................................................................................25 Figure 3.6: Layout of Sca nning Electron Microscope.......................................................26 Figure 3.7: SEM Raster Scan.............................................................................................28 Figure 3.8: X-Ray Producti on in Valence Shells...............................................................31 Figure 3.9: The X-Ray Family...........................................................................................31 Figure 3.10: The Electromagnetic Spectrum.....................................................................32 Figure 3.11: A Typical X-Ray Spectrum...........................................................................33 Figure 4.1: Direct Extr action of Bentofix..........................................................................37 Figure 5.1: (a) Isotherms for Adsorption a nd Surface Precipitation Separately (b) Apparent Isotherms for Simulta neous Adsorption and Surface Precipitation....................................................................................................49 Figure 5.2: Multisite Sorption Isotherm.............................................................................50 Figure A.1: FAA Calibration Cu rve for Sodium Desorption............................................61 Figure A.2: Sodium Desorption Curve..............................................................................61 Figure A.3: FAA Calibration Cu rve for Calcium Desorption...........................................62 Figure A.4: Calcium Desorption Curve.............................................................................62 Figure A.5: FAA Calibration Curve for Sodium 500 ppm Kinetic Test...........................64

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viii Figure A.6: Sodium 500 ppm Kinetic Test........................................................................64 Figure A.7: FAA Calibration Curve for Sodium 50 ppm Kinetic Test.............................66 Figure A.8: Sodium 50 ppm Kinetic Test..........................................................................66 Figure A.9: FAA Calibration Curve for Calcium 500 ppm Kinetic Test..........................68 Figure A.10: Calcium 500 ppm Kinetic Test.....................................................................68 Figure A.11: FAA Calibration Curve for Sodium Sorption..............................................70 Figure A.12: FAA Calibration Curve Sodium Baseline Samples......................................70 Figure A.13: Linear Isotherm-Bentonite Na.....................................................................71 Figure A.14: Freundlich Isothe rm Estimation-Bentonite Na.............................................72 Figure A.15: Freundlich Is otherm-Bentonite Na...............................................................72 Figure A.16: Langmuir Isotherm Estimation-Bentonite Na..............................................73 Figure A.17: Langmuir Isotherm-Bentonite Na.................................................................73 Figure A.18: Linear Isotherm-Bentofix Na.......................................................................74 Figure A.19: Freundlich Isothe rm Estimation-Bentofix Na..............................................75 Figure A.20: Freundlich Isotherm-Bentofix Na.................................................................75 Figure A.21: Langmuir Isotherm Estimation-Bentofix Na................................................76 Figure A.22: Langmuir Isotherm-Bentofix Na..................................................................76 Figure A.23: Linear Isotherm-1% HC Na..........................................................................77 Figure A.24: Freundlich Isothe rm Estimation-1% HC Na................................................78 Figure A.25: Freundlich Isotherm-1% HC Na...................................................................78 Figure A.26: Langmuir Isotherm Estimation-1% HC Na..................................................79 Figure A.27: Langmuir Isotherm-1% HC Na....................................................................79 Figure A.28: Linear Isotherm-3% HC Na..........................................................................80

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ix Figure A.29: Freundlich Isothe rm Estimation-3% HC Na................................................81 Figure A.30: Freundlich Isotherm-3% HC Na...................................................................81 Figure A.31: Langmuir Isotherm Estimation-3% HC Na..................................................82 Figure A.32: Langmuir Isotherm-3% HC Na....................................................................82 Figure A.33: Linear Isotherm-1% MA Na.........................................................................83 Figure A.34: Freundlich Isothe rm Estimation-1% MA Na...............................................84 Figure A.35: Freundlich Isotherm-1% MA Na..................................................................84 Figure A.36: Langmuir Isotherm Estimation-1% MA Na.................................................85 Figure A.37: Langmuir Isotherm 1% MA Na....................................................................85 Figure A.38: Linear Isotherm-3% MA Na.........................................................................86 Figure A.39: Freundlich Isothe rm Estimation-3% MA Na...............................................87 Figure A.40: Freundlich Isotherm-3% MA Na..................................................................87 Figure A.41: Langmuir Isotherm Estimation-3% MA Na.................................................88 Figure A.42: Langmuir Isotherm-3% MA Na...................................................................88 Figure A.43: FAA Calibration Curve for Ca lcium Samples 500 ppm, 100 ppm, and 10 ppm Initial Concentrations.......................................................................89 Figure A.44: FAA Calibration Curve for Ca lcium Samples 50 ppm, 1 ppm, and 0.1 ppm Initial Concentrations...........................................................................89 Figure A.45: Linear Isotherm-Bentonite Ca......................................................................90 Figure A.46: Freundlich Isotherm Estimation-Bentonite Ca ............................................91 Figure A.47: Freundlich Is otherm-Bentonite Ca ..............................................................91 Figure A.48: Langmuir Isotherm Estimation-Bentonite Ca .............................................92 Figure A.49: Langmuir Isotherm-Bentonite Ca ................................................................92 Figure A.50: Linear Isotherm-Bentofix Ca .......................................................................93

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x Figure A.51: Freundlich Isotherm Estimation-Bentofix Ca .............................................94 Figure A.52: Freundlich Isotherm-Bentofix Ca ................................................................94 Figure A.53: Langmuir Isotherm Estimation-Bentofix Ca ...............................................95 Figure A.54: Langmuir Isotherm-Bentofix Ca..................................................................95 Figure A.55: Linear Isotherm-1% HC Ca .........................................................................96 Figure A.56: Freundlich Isothe rm Estimation-1% HC Ca ................................................97 Figure A.57: Freundlich Isotherm-1% HC Ca ..................................................................97 Figure A.58: Langmuir Isotherm Estimation-1% HC Ca .................................................98 Figure A.59: Langmuir Isotherm-1% HC Ca ...................................................................98 Figure A.60: Linear Isotherm-3% HC Ca .........................................................................99 Figure A.61: Freundlich Isothe rm Estimation-3% HC Ca ..............................................100 Figure A.62: Freundlich Isotherm-3% HC Ca ................................................................100 Figure A.63: Langmuir Isotherm Estimation-3% HC Ca ...............................................101 Figure A.64: Langmuir Isotherm-3% HC Ca .................................................................101 Figure A.65: Linear Isotherm-1% MA Ca ......................................................................102 Figure A.66: Freundlich Isothe rm Estimation-1% MA Ca .............................................103 Figure A.67: Freundlich Isotherm-1% MA Ca ...............................................................103 Figure A.68: Langmuir Isotherm Estimation-1% MA Ca ..............................................104 Figure A.69: Langmuir Isotherm-1% MA Ca .................................................................104 Figure A.70: Linear Isotherm Estimation-3% MA Ca ....................................................105 Figure A.71: Freundlich Isothe rm Estimation-3% MA Ca .............................................106 Figure A.72: Freundlich Isotherm-3% MA Ca ...............................................................106 Figure A.73: Langmuir Isotherm Estimation-3% MA Ca ..............................................107

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xi Figure A.74: Langmuir Isotherm-3% MA Ca .................................................................107 Figure A.75: Unexposed Bentonite x100.........................................................................108 Figure A.76: Unexposed Bentonite x250.........................................................................108 Figure A.77: Unexposed Bentonite x3500.......................................................................108 Figure A.78: Unexposed Bentonite Spectrum.................................................................109 Figure A.79: Unexposed Bentofix x100..........................................................................110 Figure A.80: Unexposed Bentofix x500..........................................................................110 Figure A.81: Unexposed Bentofix x2000........................................................................110 Figure A.82: Unexposed Bentofix Spectrum ..................................................................111 Figure A.83: Unexposed Medium Anionic Polymer x100..............................................112 Figure A.84: Unexposed Medium Anionic Polymer x600..............................................112 Figure A.85: Unexposed Medium Anionic Polymer x3000............................................112 Figure A.86: Unexposed Medium Anionic Polymer Spectrum.......................................113 Figure A.87: Unexposed High Cationic Polymer x70.....................................................114 Figure A.88: Unexposed High Cationic Polymer x1000.................................................114 Figure A.89: Unexposed High Cationic Polymer x10000...............................................114 Figure A.90: Unexposed High Cationic Polymer Spectrum ...........................................115 Figure A.91: Sodium Exposed Bentonite x500...............................................................116 Figure A.92: Sodium Exposed Bentonite x10000...........................................................116 Figure A.93: Sodium Exposed Bentonite x25000...........................................................116 Figure A.94: Sodium Exposed Bentonite Spectrum .......................................................117 Figure A.95: Sodium Exposed Bentofix x500.................................................................118 Figure A.96: Sodium Exposed Bentofix x10000.............................................................118

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xii Figure A.97: Sodium Exposed Bentofix x25000.............................................................118 Figure A.98: Sodium Exposed Bentofix Spectrum..........................................................119 Figure A.99: Sodium Exposed 3% Medium Anionic x500.............................................120 Figure A.100: Sodium Exposed 3% Medium Anionic x10000.......................................120 Figure A.101: Sodium Exposed 3% Medium Anionic x25000.......................................120 Figure A.102: Sodium Exposed 3% Medium Anionic Spectrum....................................121 Figure A.103: Sodium Expos ed 3% High Cationic x500................................................122 Figure A.104: Sodium Expos ed 3% High Cationic x5000..............................................122 Figure A.105: Sodium Expos ed 3% High Cationic x25000............................................122 Figure A.106: Sodium Exposed 3% High Cationic Spectrum.........................................123 Figure A.107: Calcium Exposed Bentonite x500............................................................124 Figure A.108: Calcium Exposed Bentonite x10000........................................................124 Figure A.109: Calcium Exposed Bentonite x25000........................................................124 Figure A.110: Calcium Exposed Bentonite Spectrum.....................................................125 Figure A.111: Calcium Exposed Bentofix x500..............................................................126 Figure A.112: Calcium Exposed Bentofix x10000..........................................................126 Figure A.113: Calcium Exposed Bentofix x25000..........................................................126 Figure A.114: Calcium Exposed Bentofix Spectrum......................................................127 Figure A.115: Calcium Exposed 3% Medium Anionic x500..........................................128 Figure A.116: Calcium Exposed 3% Medium Anionic x10000......................................128 Figure A.117: Calcium Exposed 3% Medium Anionic x25000......................................128 Figure A.118: Calcium Exposed 3% Medium Anionic Spectrum...................................129 Figure A.119: Calcium Exposed 3% High Cationic x500...............................................130

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xiii Figure A.120: Calcium Exposed 3% High Cationic x10000...........................................130 Figure A.121: Calcium Exposed 3% High Cationic x25000...........................................130 Figure A.122: Calcium Exposed 3% High Cationic Spectrum........................................131

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xiv INORGANIC SORPTION IN POLYMER MODIFIED BENTONITE CLAYS Melody Schwartz Nocon ABSTRACT In 1986, geosynthetic clay liners (GCLs) were invented and successfully used as a replacement for the soil layer in composite lining systems. In some applications an additive (polymer) is mixed with the bentoni te to increase performance, especially in those that have low concentrations of sodium bentonite (EPA 2001). Studies showing significant increases in hydraulic conductivity values for bentonite in the presence of high salt concentrations are frequently documented and there is a risk of early breakthrough due to perf ormance failure of the GCL clay component. (Ashmawy et al, 2002). It has also been st ated that sodium, potassium, calcium, and magnesium have such a high affinity for the clays surface other chemical species have little chance of attenuation (EPA 2001). For these reasons, research ing sorption in the presence of major salt cations and polymers gains great importance. Distribution coefficients were extrapolat ed from Linear, Freundlich and Langmuir sorption isotherms for sodium and calcium ca tions modeled from data collected from batch tests of sodium bentonite and vari ous manufactured and custom mixed polymer modified bentonites. Surface characterization be fore and after calcium or sodium solution exposure of all tested media was accomplished by use of scanning electron microscopy and energy dispersive x-ray analysis.

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CHAPTER ONE INTRODUCTION 1.1 Significance In 1986, geosynthetic clay liners (GCLs) were invented and successfully used as a replacement for the soil layer in composite landfill lining system s (EPA 2001). GCLs normally consist of either bentonite clay sa ndwiched between two geotextiles or a layer of bentonite clay adhered to the surface of a geomembrane. GCLs have become a popular component to include in composite landfill li ning systems because bentonite clay has a high swell potential and very low hydraulic c onductivity. However, the original values of hydraulic conductivity for the bentonite compone nt of a GCL can increase significantly after installation and exposure to highly c oncentrated inorganic leachate (Petrov et al, 1997; Shackelford et al, 2000; and Elhajji et al, 2001). According to Elhajji et al (2001), additional polymer treatment of the bentonite component of GCLs can counteract this negative effect and help mainta in low values of hydraulic co nductivity in the presence of highly concentrated inorganic single speci e solutions. Recent research has been performed in regards to this suggestion with mixed result s for performance to hydraulic conductivity (Schenning, 2004). Estimating specific discharge by experime ntally defining hydraulic conductivity can be useful in reference for predictions to tim e, but defining distribution coefficients for various isotherm models can also be help ful in transport modeling for the amount of exposure to inorganic species. 1

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1.2 Objective One purpose of this research was to defi ne distribution coefficients of polymer modified bentonite clay in the presence of single inorganic species so lutions. Sodium and calcium, two inorganic species commonly found in incinerator fly ash leachates at very high concentrations, were used as challenge chemicals. Typical characteristics for incinerator fly ash leachates ar e listed in the table below. Table 1.1: Leachate Properties (Ashmawy et al, 2002) TEST LEACHATE L-1 L-2 L-3 LANDFILL TYPE Co-disposal Co-disposal Ash monofill pH 6.30 6.55 7.24 Ca 2+ (mg/L) 1,150 2,625 5,120 Na + (mg/L) 2,200 300 1,640 Distribution coefficients for sodium and calcium were extrapolated from experimental data modeling of Linear, Freundlich, and Langmuir sorption isotherms. In addition to defining distribution co efficients, surface characterization of polymer modified bentonite clays before a nd after exposure to the challenge chemicals were described by use of scanning electron microscopy (SEM) and energy dispersive xray analysis (EDX). 1.3 Scope of Work One manufactured polymer modified cl ay, Bentofix, was tested. High cationic polyacrylamide and low anionic polyacrylamid e-bentonite solutions at one and three percent by solid weight concentrations were tested. Untreated sodium bentonite was tested to provide a point of reference. Fixed experimental variables included temper ature, pH, and initial sodium or calcium concentrations. The modified variable was th e amount of solids in solution. Data was fit to empirical Linear, Freundlich, and Langmuir isotherms. 2

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CHAPTER TWO THEORETICAL BACKGROUND 2.1 Material Classification 2.1.1 General Clay Classification All clay minerals belong to the phyllo silicate mineral family, where they primarily differ from each other by their structural arrangement of silicon tetrahedron and aluminum or magnesium octahedron sheets. Th ese sheets bond to each other in 1:1 or 2:1 ratios of silicon tetrahedron to aluminum oc tahedron in order to form semi-basic unit layers. Figure 2.1 (a) Silica Tetrahedral Sheet (b) Al umina Octahedral Sheet (Mitchell, 1993) Additionally, specific clays within the sa me clay mineral group can be further distinguished from other group members by the type and extent of isomorphous substitutions that occur in their structural arrangement. Isomorphous substitutions in clays occur when other cations are present in positions of the cr ystal structure where aluminum or silicon cations should have been during the formation process of the clay. 3

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These cations often have a smaller positive charge than that of aluminum or silicon cations and, consequently, result in a net ne gative charge present at the surface of the clay. Net negative surface charges present on th e semi-basic unit layers facilitate the attraction of cations from their natural surrounding solution in order to achieve neutrality. These surface cations can ofte n be replaced by other types of cations, and, as such, are termed exchangeable cations. Cation exchange capacity is a sorp tive property of a specific clay used to describe the quantity of exchangeable cations and is commonly expressed in units of milliequivalents per 100 grams of dry clay (Mitchell, 1993). During interlayer bonding between semi-basic unit layers, these surface cations become interlayer cations. Interlayer bondi ng between semi-basic unit layers can be controlled by interlayer cations and/or pol ar molecules, such as water. Some bonds involving interlayer cations betw een the semi-basic unit layers can be so strong that the layers will not separate in the presence of wa ter or any other polar molecules. At other times, interlayer cations will hydr ate in the presence of polar molecules to form a weaker bond between semi-basic unit layers and will result in swel ling of the clay. Figure 2.2: Interlayer Bondi ng Via Hydration/Dipole At traction (Mitchell, 1993) 4

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Interlayer bonding for neutral semi-basic unit la yers can also be attributed to by van der Waals forces and/or hydrogen bonding. Figure 2.3: Synthesis Patterns for Clay Minerals (Mitchell, 1993) 5

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2.1.2 Classification of Sodium Bentonite Bentonite clay is commonly used in geos ynthetic clay liners. Bentonite clay, an alteration product of volcanic ash, is primarily composed of montmorillonite, which is the most common type of smectite mineral. Montmorillonite has a 2:1 aluminosilicate semibasic unit layer, where the 2: 1 ratio refers to two tetrahedral sheets sandwiching an octahedral sheet in between. (a) (b) Figure 2.4: The Semi-Basic Unit Layer of Montmorillonite (a) Two Dimensional Representation with Charge Distributi on and Average Range of Thickness (b) Three Dimensional Representation Incl uding the Interlayer (Mitchell, 1993) The outsides sheets of montmorillonite consis t of silica, where each silicon ion in the sheet is surrounded by four oxygen ions. The middl e sheet of montmorill onite consists of aluminum, where each aluminum ion is surrounded by six oxygen ions. 6

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In montmorillonite, isomorphous substitution is demonstrated by the presence of a magnesium cation for every sixth position in the octahedral sheet meant for an aluminum cation. The formula per unit cell for montmorillonite is (OH) 4 Si 8 (Al 3.34 Mg 0.66 )O 20 In sodium bentonite, sodium is the exchangeable interlayer cation. In terlayer cations in smectites form weak bonds between semi-basic unit layers and are easily hydrated by polar molecules. This phenomenon gives sm ectites the ability to swell to large proportions upon full hydration. 2.1.3 General Synthetic Water-Sol uble Polymer Classification 2.1.3.1 Structure and Water Soluble Properties Structurally, a polymer, or macromolecule, is essentially a long string of joined monomers, where monomers are simple molecu les. Characteristic properties of polymers are controlled by functional groups located wi thin their chemical structure. Functional groups are comprised of one or more atom s attached to the hydrocarbon chain of a polymer (Hill & Petrucci, 1999). Polar functional groups in the polymer chain are responsible for both water solubility and inte ractions at the clay surface (Theng, 1979). 2.1.3.2 Polyelectrolytes Polyelectrolytes are water soluble polymers that disassociate in water to create either polycations or polyanions along with an equivalent amount of ions with a small charge and opposite sign. The corresponding i ons may also have no charge at all. 7

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2.1.3.3 Polymerization Polymerization is the chemical process in which a monomer is converted to a polymer. Copolymerization is the chemical pr ocess in which more than one monomer is converted to a polymer. The general reac tion for polymerization is defined as nM [M] n Where M stands for monomer, and n stands for the degree of polym erization. A high polymer has a high molecular weight and hi gh degree of polymerization. Polymerization can be divided into two groups according to the mechanism of polymer formation: StepGrowth or Chain. Step-Growth polymerization occurs when functional groups of multiple monomers have reactions that create a li nk between the monomers. Chain or addition polymerization occurs when either an ionic or free radical catalyst opens the double bond of an unsaturated monomer to form an activat ed monomer. Additions of monomers to the activated monomer give rise to polymers. Free-radical, anionic, and cationic polymerization are all chain processes (Alger, 1989). In 1979, Theng classified the three main groups of synthetic polyelectrolytes based on their net ionic charge: nonionic, anio nic, and cationic. Nonionic polymers have no charge, anionic polymers have a negative charge, and cationic polymers have a positive charge. 8

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2.1.3.4 Polyacrylamide Polyacrylamide is created fr om the free radical polymerization of acrylamide. It is commonly used as a flocculating agent and gel for electrophoresis because of its high affinity for water (Alger, 1989). Polyacrylamid es high affinity for water is due to its chemical structure. Figure 2.5: Polyacrylamide The NH 2 groups allow unlinked amides to form hydrogen bonds with water. However, ions present in solution can interfer e with the hydrogen bonds and cause the polyacrylamide gel to release the water molecules. Testing materials for this study were created by the ionic polymerization of polyacrylamide. High cationic and medium anionic polymers with polyacrylamide backbones were tested. 9

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2.2 Clay Dispersions 2.2.1 Colloids and Sols Clay particles naturally occur in water as colloids. Colloids are particles with a high surface area to mass ratio that are susp ended in water due to their extremely small size, state of hydration, and surface electric charge A colloidal dispersion in water is also known as a sol (Viessman and Hammer, 2004). Repulsion or attraction between particles is dependent upon the pH and the ionic strength of the solution. Figure 2.6: A Stable Sol (Viessman and Hammer, 2004) 2.2.2 The Diffuse Double Layer Sodium is present in dry sodium bentonite clay as strongly bonded interlayer or surface cations and, in excess, as salt precipitate (Mitchell, 1993). Figure 2.7: Precipitate Salts and Inte rlayer Cations (Santamarina, 2001) 10

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When bentonite clay is placed in water, sa lt precipitates are separated into anions and cations through the thermal agitation of water molecules. These newly created ions are surrounded by hydration shells (Santamarina, 2001). Figure 2.8: Process of Hydration for NaCl (Santamarina, 2001) The hydrated cations diffuse away from the surface of the bentonite in the direction of the concentration gradient to fulfill the laws of solution equilibrium. This phenomenon creates an ionic distribution around the clay particle that is influenced by both the net negative surface charge of the clay and the concentration gradient (Mitchell, 1993). 11

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(a) (b) Figure 2.9: (a) Picture of I onic Distribution Near the Surface of Clay (b) Ionic Concentration as a Function of Distance from the Clay Surface (Mitchell, 1993) A basic model for ionic distribution around the surface of a colloid is the Diffuse Double Layer model. (a) ) Molecular View of the Diffuse Double Figure 2.10: (a) The Diffuse Double Layer (b Layer (Viessman & Hammer, 2005) 12

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(b) Figure 2.10 (continued) 2.2.2.1 Surface Complexation in the Stern Layer The layer closest to the surf ace of the colloid is the Stern Layer, which consists of a fixed layer of cations electro statically attracted to the negative surface of the clay. Within the Stern layer, both inner and outer sphere complexes are present. Inner sphere complexes are ions that have lost all or a partial amount of their hydration shells and are oriented in such a way that there are no water molecules located between the bonded ion and cl ay particle surface. Figure 2.11: An Inner Sphere Surface Complex (Sposito, 2004) Clay Layers ter Molecules K+ Counterion Tetrahedral Charge Site Wa 13

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Outer sphere complexes are still at a fixed position relatively of the clay particle, but they still retain their primary hydration shell. Outer sphere lexes are exchangeable cations. close to the surface comp H2O Molecule Octahedral Charge Site on the Basal Plane (Siloxane Surface) Figure 2.12: An Outer Sphere Complex (Sposito, 2004) Figure 2.13: Inner and Outer Sphere Complexation (Santamarina, 2001) Na+ Counterion 14

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2.2.2.2 Diffuse Ions in the Guoy-Chapman Layer The layer surrounding the Stern layer is a diffuse ion swarm called the Guoy Chapman Layer. Counterions, or diffu se i ons, located in the Guoy-Chapman layer are also exchangeable. ce have only been addressed in reference to simple cations For this research, it is also important to address polymer interactions at the surface of the clay. Polymer molecules must have a molecular or coil size that is small enough to penetrate through the in terlayer spacing of clay in order to interact with the surface of the clay. Nonionic polymer molecules sorb to the clay surface only af ter desorption of a large amount of solvent (water) molecules pr eviously present at the clay surface. Adsorption of the polymer chain is dependent on flexibility a nd properties of its functional groups. At the clay surface, polymer chains orie nt themselves into various shapes that allow attachment to the surface via segment-surface bonds. Figure 2.14: Ions in the Stern a nd Guoy-Chapman Layer (Sposito, 1989) 2.2.2.3 Polymer Interactions in the Diffuse Double Layer Guoy-Chapman Layer Stern Layer Up to this point of discussion, sorptive properties of the clay surfa 15

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Figure 2.15: The Process of Adsorption for an Uncharged Polymer Molecule at the Clay y exchange of the many c e aals forces, surface complexation, ionic b Surface (Theng, 1979) For polycations, adsorption at the surface of the clay occurs b ations for one polycation. The amount of polycations adsorbed to the surface of the clay is dependent on the charge density of the polycation and the cation exchange capacity of the clay. For polyanions, there are many different mechanisms of adsorption. These includ electrostatic attraction, hydrogen bonding, Va n der W onding to other cations in the diffuse double layer, and anionic exchange at the positive crystal edges of the octahedral sheet (Theng, 1979). 16

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2.2.3 Sol Destabilization Destabilization of hydrophobic sols, or co lloidal dispersions, can be achieved by an der Waals Forces and Brow nian movement. Increasing Van der W orces of attraction felt between two particles, and Br ownian move motion of colloids in solution, increases the like lihood of flocculation, or eration, between particles. Colloids are also destabilized by the add coagulant, which can be a salt or cationic polymer. 2.2.3.1 Addition of Neutral Salts Salt cations in solution serve as c ounterions that reduce the thickness of the diffuse double layer around colloids enough to perm aals forces of attraction increase as the particles become increasing V aals forces, the f ment, the random agglom ition of a it contact between particles. Van der W closer and facilitates Figure 2.16: Destabilization and Coagulation by Suppression of the Diffuse Double Layer flocculation. (Viessman & Hammer, 2005) 17

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2.2.3.2 Addition o f Polyelectrolytes 05) Isotherms A sorption isotherm is an equation that expresses the relationship between the amount of sorbed phase species to the amount of solution phase species for the same species in a system that is in equilibrium. The distribution coeffici ent, often denoted as Kd, is present in all sorption is otherms and is a ratio of the sorbed phase concentration to the solution phase concentration. When gr aphing a sorption isotherm, the sorption density, often denoted as Q, is labeled on the y axis and the equilibrium concentration, on the x-axis (Ben jamin, 2002). The three types of isotherms selected for data modeling in this research included Linear, Freundlich, and Langmuir Isotherms. Equations and typical units used for modeli ng sorption isotherms are further discussed in Chapter 5. The long chains of cationic polymers allow them to be excell ent coagulants, as they are able to adsorb to the surfaces of multiple colloids. This phenomenon creates a bridging effect between the colloids that results in flocculation. Figure 2.17: Colloid Agglomeration via Par ticle Bridging (Viessman & Hammer, 20 2.3 Sorption often denoted as C e is labeled 18

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2.3.1 L l upper limit for sorption capacity. inear Isotherm 2.3.2 F on Figure 2.19: A Typical Freundlich Isotherm inear Isotherm A linear sorption isotherm is the simple st type of isotherm. It expresses a proportional relationship between sorption density and equilibrium concentration. One faulty attribute of this type of isotherm is its lack of no theoretica Figure 2.18: A Typical L reundlich Isotherm A Freundlich isotherm displays an e xponential relationship between the sorpti density and equilibrium concentration. The Freundlich isotherm has the same faulty attribute of the linear isotherm; it lacks a theoretical upper limit for sorption capacity. Q,on Density C Equil Sorptiequilibriumibrium Concentration Q, Sorption Density Cequilibrium, Equilibrium Concentration 19

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2.3.3 Langmuir Isother m rption r A Langmuir sorption isotherm displays a finite relationship between the so density and the equilibrium concentration. M odeling with a Langmuir sorption allows fo an establishing of a theoretical upper limit for the sorption density. Q, Sorption Density Cequilibrium, Equilibrium Concentration Figure 2.20: A Typical Langmuir Isotherm 20

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A pC-pH diagram was used to pred ict when the precipitation of CaCO3(s) would occur. Constants used for calculations include an assumed PCO2=10-3.5 atm, pKa1= 6.35, pKa2= 10.33 for H2CO3, and pKso= 8.48 for CaCO3(s) (Benjamin 2002). Species included in calculations included H+, OH-, H2CO3, HCO3 -, and CO3 2-, Ca2+ and CaCO3 (s). CHAPTER THREE EXPERIMENTAL BACKGROUND 3.1 Water Chemistry pC-pH Diagram: Calcium Solubility Curve, PCO2=10-3.5 atm 0 01234567 5 10 15 20 891011121314 pHpC pCa2+=1.9 pOH pH pH2CO3 pHCO3pCO32CT Ca2+ Figure 3.1: Calcium Carbonate Solubility Curve Precipitation of CaCO3(s) occurs in the shaded region of the pC-pH diagram between the pCT line and the pCa2+ lines. For all experiments, the working pH ranged from 6.75 to 7.25 and the maximum concentration of Ca2+was 500 mg/L or 0.012476 mol/L. 0.012476 mol/L Ca2+ corresponds to a pC value of 1.9. No CaCO3(s) is predicted to form. 21

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3.2 Atomic Absorption Absorption spectroscopy in which the radiation absorbed by atoms is measured. Atomi adiation by atoms and e correct wavelength excites an atom in ground state to a higher energy Where A is absorbance, I0 is the incident light intensity, I is the transmitted light intensity, kv is the absorption coefficient, and l is the path length. Absorbance, A of light is directly the light. Therefore, be the relationship between absorption and concentration (Ebdon et al, 1998). 3.2.1 Flame Atomic Absorption Spectrometry (FAAS) 3.2.1.1 Source Instrumentation FAAS can use either a hollow-cathode lamp or an electrodeless discharge lamp as a source in its instrumentation. This research utilized hollow-cathode lamps for source instrumentation, and a general schematic for this lamp can be seen below: volves the proce ss in c absorption is th e absorption of light r occurs when light of th level. The transition from a ground state (E 0 ) to an excited state (E j ) can be written as E 0 E j The following mathematical expressi on is used to describe atomic absorption: A=log( I 0 /I )= k v l log e proportional to the number of atoms, or concen tration, that absorbed a linear expression can be used to descri Figure 3.2: The Hollow-Cathode Lamp (Ebdon et al, 1998) 22

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The hollow cylindrical c athode is specifically coated with a metal of interest. The glass envelop o Further collisions excite the metal atoms and a ch aracteristic spectrum of the metal is produced. ne ry compounds are used or interferences are s path length and orients the proper Components for a flame are as follows: Figure 3.3: A Premixed Fl ame (Ebdon at al, 1998) e is filled with an in ert gas at 1 to 5 Torrents, wh ich creates the proper conditions to allow discharges to con centrate in the hollow cylindric al cathode when a voltage potential of 500 V is applied be tween the electrodes. Ions ar e created at the anode due t the charging of the inert ga s and these ions subsequently accelerate and bombard the cathode. This bombardment causes the metal atom s in the coating to sputter out of the cathode cup. 3.2.1.2 Flame The purpose of the flame in atomic abso rption spectrometry (AAS) is to produce ground-state atoms. Gas mixtures are used as fuels for flames. Air acetylene mixtures are generally sufficient enough to produce ground-st ate atoms, but nitrous oxide-acetyle mixtures are required when refracto commonly encountered. The slot burner in AAS control portion of the flame for viewing. 23

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Because atoms are not uniformly distributed, hei ght of the burner should be adjusted unt the region of optimum absorption can be found. 3.2.1.3 Sample Introduction and Atomization Analytes are introduced into the proce ss through a concentric nebulizer system. il Figure 3.4: Concentric Nebuliz er System for a Premixed Burner (Ebdon et al, 1998) Analytes are drawn through the capillary tube and leave the nebulizer orifice as a mist due to the pressure drop created by the inco ming oxidant. As the nebulized sample moves through the plastic expansion chamber any la rge droplets will collect on the baffles in order to ensure that only the smallest particles reach the flame. Upon introduction to the flame, droplets undergo desolvation in the preheating zone. Most vapors break down spontaneously to atoms in the flame, but some vapors can be refractory (Ebdon et al, 1998). 24

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3.3 Scanning Electron Microscopy (SEM) Images produced by the SEM are dependent on the deflection of secondary and backscattered (elastically s cattered) electrons pres ent at the sample surface. These electron ns produced by the electron beam. the SEM include no scattering of electrons at the sample surface, inelastic scattering, photon production, auger electron producti on, x-ray production, cathodoluminescence, and electron energy loss. s are deflected by bo mbarding incident electro Various other interactions that may occur by the bombardment of incident electrons in Figure 3.5: SEM Surface Interactio ns (Goldstein et al, 1992). 3.3.1 Basic Instrumentation The three main components of the SE M include the electr on optical column, vacuum system, and the electronics and display system. 25

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Figure 3.6: Layout of Scanning El ectron Microscope (Lawes, 1987). 3.3.1.1 Electron O Electron gun Anode Disc Waveform Generato r ptical Column The basic electron optical column contai ns an electron gun, anode disc, condenser lens, scan coils, objective lens the specimen sample holder, and the detector. A beam of electrons is produced by th e electron gun. Thermoionic emis sion of freed electrons is produced via the heating of a filament in the electron gun. A hi gh voltage potential, called the acceleration voltage, is produced be tween the filament in the electron gun and the anode disc and a beam of electrons are accelerated away from the filament. The beam first passes trough a series of lenses whic h are responsible for focusing the beam. The diameter of the beam is reduced from a bout 50 micrometers to five nanometers by the condenser lenses, and can be even further reduced by manually changing the size of the aperture. The objective lens ensures that the b eam has it smallest diameter when it strikes the specimen surface. Horizontal and vertical scan coils control the scanning direction of the beam as it passes next to them (Lawes, 1987). Condensor Len s Scan Coils CRT Brightness Objec Lens tive Specimen Vacuum Connection Detector Signal Amplifier CRT Display Screen Scan Coils Magnification Control Control 26

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3.3.1.2 Vacuum System The beam of the electrons passing thr ough the electron optical column and onto the sample surface cannt in the open at mois environment, the beam would only travel a fe coming scattere nent in the air. The vacuu syst em attached to the electron optical column rem olecules and all travel the electron gun to the sample without any interference. Vacuum syst ems may consist of a series of ion pumps, rotary pumps and a turbo mo 3.3.1.3 Elec stem plifier, waveform generat ls, a cathode ray tu be (CRT) brightness control, a CRT all ot exis sphere. In th w mil limeters before be d by gas molecules atural ly pre s m ows the beam to oves these m from lecular pump. tronics an d Display Sy The basic electronics and display system c onsists of a signal am or, magnification control, scan coi display screen, and a computer. In or der to produce an image, the electron beam must scan over the sample for the detector in the electron opti cal column to take information, or signals, over many points as it moves along the surface of a sample. In SEM systems, the diameter of a point is equa l to the diameter of the electron beam as well as the thickness of a line on a raster scan. The width of a line on the raster scan consists of 1,000 points. One frame has a thic kness of a thousand lines. Therefore, the SEM must scan over 1,000,000 points to produc e a single image in a raster scan. 27

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Figure 3.7: SEM Raster Scan (Lawes, 1987 ) he diameter: Vertical and horizontal scan coils in the electron optical column are connected to the magnification control and waveform generator. The waveform generator supplies the vertical and horizontal scan coils in the el ectron optical column with specific current waveforms. The movement of the electron beam over the sample is dictated by the scan coils in the electron optical column. The waveform generator is also connected to a pair of vertical and horizontal s can coils belonging to the CRT brightness control and display screen. In this way, the image on the CRT screen corresponds to the raster scan and t screen resolution is ultimately dictated by the magnification control. The following equation expresses the relationship between magnification, screen resolution, and beam diamete r beam resolution screen ion magnificat 28

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3.3.2 Operational Parameters quality of the im erational parameters is essential in order to attain 3.3.2.1 Condenser Lens diameter at a certain value m meter will enhance the etting will concen trate the beam and roduce higher signals and resolution. t ple. can in itself has a very low quality. Increasing the scan speed increases the amount of raster scans or images displayed per unit time. Therefore, increasing the scan speed should result in a higher quality image. However, signal amplifiers attached to the detector will pick up more random electrons in addition to the signa l electrons when the scan speed is increased. The presence of random electrons can be inte rpreted in an image Changing the operational parameters in the SEM can enhance or reduce the age collected. Understanding and adjusting op the level of quality desired. As seen in the prior equation, screen resolution is inversely proportional beam agnification. De creasing the beam dia screen resolution. Increasing the condenser le ns s p 3.3.2.2 Accelerating Voltage Image resolution is directly proportional to acceleration volta ge, therefore, the highest resolution commonly corr esponds to adjusting the SE M controls to the highes maximum acceleration voltage value possibl e. However, high acceleration voltage can cause charging and damage of a specimen due to higher beam en ergies and specimen interaction volumes. 3.3.2.3 Scan Speed One raster scan consists of one collected signal per point scanned on the sam Because the efficiency of the SEM detector a nd interactions at the surface is very low, one raster s 29

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as noi e is pr oduced at very high scan speeds. Therefore, picture w hysical distance between the final lens in the electron optical nged by controls on the SEM, and the control on the SEM stance. Resolution is proportional to the depth of ses age. Also, the aperture should always be aligned at a position in which it does not block any portion of the pa ssing electron beam. Incorrect aperture lignm 3.4 Energy Dispersive XRay (EDX) Analysis The EDX spectrometer can be attached to a spare vacuum port in an SEM when EDX analysis is desired. X-rays can be produced when incident el ectrons from the electron beam interact with the specimen. A bombardi ng incident electron can eject a shell electron in an atom belonging to the specimen and, if the shell electron belongs to an inner shell (K,L, or M), se and, therefore, a noisy imag s should be collected at an acceptable scan speed that is not too high or too lo often this is still the lowest scan speed available on the SEM. 3.3.2.4 Working Distance Working distance is the p column and the surface of the sample. The working distance can be manually changed by adjusting the Z-axis of the speci men sample holder. The working distance should always be within the depth of focus of the lens, or the image will not be in focus. The depth of focus can be manually cha is often labeled wor king di focus, therefore decreasing the depth of focus and working distance increases the resolution of the image. 3.3.2.5 Aperture Size and Alignment Decreasing the aperture size decreases the beam diameter and, therefore, increa the resolution of an im aent will result in darkened edges around the image. 30

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a photon of electromagnetic radiat ion is produced that is an X-ray when an electron from a lower energy shell drops down to fill the vacancy. Figure 3.8: X-Ray Production in Valence Shells (Lawes, 1987) The three types of X-rays that can be produced from interacti ons in the inner shells of a specific atom consist of K, K, and L. Where denotes a one level rise in energy, and denotes a two level rise in energy. Figure 3.9: The X-Ray Family (Lawes, 1987) 31

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Radiation produced from interactions of the electron beam and sample specimen leave the surface of the specimen and strike a crystal. Radiation will only emerge from the crystal if they are within a range of wavelengths corresponding to x-rays (0.1-1 nm) of specified Elements (Braggs Law). Figure 3.10: The Electromagnetic Spectrum (Lawes, 1987) The x-rays leaving the crysta l enter a gas flow proportional detector. The output current pulse from the gas flow proporti onal detector is propor tional to the energy of the detected x-ray. The output current pulse is passed through an amplifier into a pulse shaping circuit. An x-ray count is produced from a computer that counts the number of pulses at a certain um is produced, with count values labeled on the y-axis and energy levels labeled on the x-axis. value energy level. In this way, an x-ray sp ectr 32

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Figure 3.11: A Typical X-Ray Spectrum (Lawes, 1987) The peaks are identified according to corresponding K, K, and L elemental peaks. Elemental composition can also be calcula ted by comparing count values between different x-ray counts. However, elementa l composition computed in this way may be misleading, because counts are dependant on op erating conditions and the location of the beam on the sample surface. 33

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CHAPTER FOUR METHODOLOGY 4.1 Instrumentation 4.1.1 Reverse Osmosis and Deionization Unit Prior to application, all water used for experimental preparation and during sis and Deionization (RODi) s than al A set of 10 .02, 100 .08, 500 .20, and 1000 .3 mL PYREX volumetric flasks were used to create standards for calibration of the FAA machine. All used glassware was soaked in a 5% Liquinox cleaning dete rgent, rinsed with water, immersed in a 1 N Nitric acid bath for twenty-four hour s, and rinsed with water once more before placing on drying racks. All flas ks contained stoppers at th eir mouths and beakers were covered with parafilm during storage. 4.1.3 Plastic Containers All used plastic containers, incl uding polycarbonate and polypropylene containers, were soaked in a 5% Liquinox cleaning detergent, rinsed with water, immersed in a 0.1 N sodium hydroxide base bath for an hour, rinsed with water, soaked experiments was treated by an EASYpure Reverse Osmo unit. Product water specifications include an ASTM Type I resistivity, a total organic carbon (TOC) concentration ranging from 1-5 ppb and a bacterial concentration les 1 CFU/mL. Whilst resistivity was confirmed with an internal monitor, TOC and bacteri concentration was not verified prior to use in experiments. 4.1.2 Glassware 34

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in a 0.1 N nitric acid bath for an hour, and ri sed with water once more before placing on drying racks. All open test tubes and caps were kept in clean closed plastic bags during storage. RODi produced water was used for all rinsing. 4.1.4 Mixer An ECE Compact Laboratory Mixer (CLM) 6 was used for batch solutions. The six sample jars are made with a poly acrylic and all used jars were limited to a cleaning procedure consisting of rinsing with water, soaking in 5% Liquinox detergent, and a final rinse with water before placing on drying r acks. The non-removable paddles and shafts were made out of stainless steel and were al so limited to a cleani ng procedure consisting of rinsing with water, soaking in 5% Liquinox detergent, and a final rinse with water. All lab jars were also triple-rinsed w ith water immediately before use. 4.1.5 Tube Rotator A large size Barnstead/Thermolyne Labquake Tube Rotator with a fourteen tube capacity clip bar was used to perform end over end agitation of sample bottles during sorption tests. 4.1.6 Sample Bottles for Preservation 50 mL Nalgene Oak Ridge Polycarbonate Ce ntrifuge Tubes with rubber seal caps were used as reactors in calcium sorp tion experiments. 30 mL Nalgene Oak Ridge Polycarbonate Centrifuge Tubes with rubber s eal caps were used as reactors in sodium sorption experiments. All sample bottles were triple-rinsed with water before testing. 4.1.7 Syringes and Syringe Filters B-D polypropylene 20 mL capacity sterile disp osable syringes with a luer lock tip and a 0.02 micron pore diameter sterile Whatma n Anotop disposable syringe filter with n 35

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an anopore inorganic medium and polypr opylene housing were used to separate supernatant and solids in sorption tests. 4.1.8 Sample Containers for FAAS Filter ed samples were acidified and stored in 8 mL capacity polypropylene round bottles. ions. 4.1.11 ctrode was calibrated daily with 4, 7, and 10 pH standards. ic and Immediately before FAA analysis, sa mples were diluted in sterile BD Falcon 15 mL polypropylene conical bottom graduated tubes. 4.1.9 Pipettes and Pipette Tips A set of 10-100 L, 25 L, 20-200 L 100-1000 L, and 1000-5000 L Eppendorf pipettes were used for volumetric meas urements during research experiments. 4.1.10 FAA Machine A VARIAN Fast Sequential Atomic Ab sorption Spectrometer (AA240FS) was used to analyze solut pH Electrode An Accumet (AP63) portable pH/mV/Ion meter was used to analyze solutions. The gel pH ele 4.2 Testing Materials Extra high yield, premium grade powdere d Bentonite packaged in a fifty pound paper bag from Wyo-Ben, Inc. was used in expe riments as a control. Medium anion high cationic polymers used in experiments were produced by Emerging Technologies, Inc. 36

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Table 4.1: Polymer Material Data (Schenning 2004) Y IGHT ) ENT PROD DET (lbs/ft E 6C NIC VISCOSITY i Dist. Water (CP) pH RANGE MENTAL CHARGE DENSITY Sing, 2004) /100g) UCT GE NSI CHAR BULK MOLECULAR W (Dalto WEIGHT PER IO SOLUTION 0.5% n EFFECTIVE EXPERI (chenn (mEq 3 ) ns x 10 10G80A Medium Anionic 44 3-4 40 >45 00 6-13 423.9 10G100C High Cationic 38 10 55 >5000 1-13 294.7 he ma ontents. Tnufactured polymer modified bentonite component was direc tly extracted from a donated Bentofix GCL sample by cutting the sheet open and shaking out the c Figure 4.1: Direct Extr action of Bentofix containers. Under re gular storage exposure conditions, both the bentonite and Bentofix were already partially hydrated and contained initial sodium concentrations at their surface. Polymers were stored in tig htly sealed, dark storage containers. The bentonite powder, Bentofix sample, and th e polymers were all used with no initial preparation. 4.3 Initial Media Preparation Bentonite powder, the Bentofix sample, a nd the polymers were all stored at room temperature and humidity. The bentonite and Be ntofix samples were stored in loosely sealed 37

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4.4 Desorption In order to estimate amount eacha ium and calcium refere matesotests erf on thentonite. erimeere md ribe tion characteristics at a pH of 7. A clean mix jar belonging to the ECE mixer was triple rinsed and filled with a liter of water. Aime g of benite pow was weighed out and placed in the water. T for 10 inutes and than slowed down at 70 rpm. stabilized at a pH value 7.25. Eleven 5 mL samples were withdrawn at specific times over a period of 3 days, filtered, and acidified to 5% nitric acid with a small addition of concentrated nitric acid. Resu lts for sodium and calcium desorption tests are included in Appendix A: Results. 4.5 Time to Equilibrium Kinetic experiments were performed in or der to estimate time to equilibrium and lcium concentrations for sorption tests. Time to modeled to desc ribe sorption characteristics at a pH of 7. ed s rpm the rpti to d of l we re p desorp b le orm sod ed available from Deso the exp nce nts w ria o l, de dele on esc be rp tion pprox ately on ram ton der he mixer was turned up to 360 rpm m The pH value of the solution was continuously monitored and manual 10 L incremental additions of 0.1 N nitric acid or sodium hydroxide was added to the solution until it to choose acceptable initial sodium and ca equilibrium experiments were For sodium kinetic experiments, a 500 mg/L solution of Na + was created by weighing out approximately 1.27 grams of NaCl pe llets and dissolving it in a triple rins 1 L volumetric flask filled with water. A clean mix jar belonging to the ECE mixer wa triple rinsed and filled with 1 L of the 500 mg/L Na + solution. One gram of bentonite powder was weighed out and placed in the wa ter. The mixer was turned up to 360 for 10 minutes and than slowed down at 70 rpm. The pH value of the solution was 38

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continuously monitored and m anual 10 L incremental additions of 0.1 N nitric acid or sodium d, d e, ixer itored and manual 10 L incremental additions of 0.1 N nitric acid added to the solu tion until it stabilized at a pH value 7.25. Eleven hydroxide was added to the solution un til it stabilized at a pH value of 7.25. Eleven 5 mL samples were withdrawn at specific times over a period of 3 days, filtere and acidified to 5% nitric acid with a small addition of concentrated nitric acid. A secon sodium kinetic experiment was also performe d in the same manner as described abov but a 50 mg//L solution of Na + was used in place of the 500 mg/L solution of Na + For calcium kinetic experiment s, a 500 mg/L solution of Ca 2+ was created by weighing out approximately 1.38 grams of CaCl 2 pellets and dissolving it in a triple rinsed 1 L volumetric flask filled with water. A clean mix jar belonging to the ECE m was triple rinsed and filled with 1 L of the 500 mg/L Ca 2+ solution. One gram of bentonite powder was weighed out and placed in the water. The mixer was turned up to 360 rpm for 10 minutes and than slowed down at 70 rpm. The pH value of the solution was continuously mon or sodium hydroxide was 5 mL samples were withdrawn at specific times over a period of 3 days, filtered, and acidified to 5% nitric acid with a small addition of concentrated nitric acid. Results for sodium and calcium kinetic tests are included in Appendix A: Results. 39

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4.6 Batch Sorption Tests Sorption tests for fixed slurry con centrations of Bentonite, Bentofix, and polymer modified bentonite mixes were performed at six different initial concentrations (500, 100 50, 10, 1, and 0.2 mg/L of Na a down nd filled with a liter of water. For the 1% HC-Benton ite slurry, approximately 0.01 grams of high cationic polymer and approximately 0.99 gram s of bentonite powder was weighed out and placed in 1 L of water in a mix jar. Fo r the 3% HC-Bentonite slurry, approximately 0.03 grams of high cationic polymer and appr oximately 0.97 grams of bentonite powder was weighed out and placed in 1 L of water in a mix jar. The mixer was turned up to 360 rpm for 10 minutes and than slowed down at 70 rpm. The pH value of the solution was + or Ca 2+ ). Batch sorption experiments were modeled to describe sorption characteristics at a pH of 7. 4.6.1 Slurries 4.6.1.1 Bentonite and Bentofix Slurries A clean mix jar belonging to the ECE mixer was triple rinsed and filled with liter of water. Approximately one gram of bentonite powde r was weighed out and placed in the water. The mixer was turned up to 360 rpm for 10 minutes and than slowed at 70 rpm. The pH value of the solution was continuously monitored and manual 10 L incremental additions of 0.1 N nitric acid or sodium hydroxide was added to the solution until it stabilized at a pH value 7.25. The solution was allowed to equilibrate overnight before testing. The same procedure was re peated using approximately one gram of Bentofix. 4.6.1.2 HC or MA Bentonite Slurries Two clean mix jars belonging to the ECE mi xer were triple rinsed a 40

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continuously monitored an d manual 10 L incremental additions of 0.1 N nitric acid or 0 mg/L Na+ solution was created daily during sorption experiments by pellets into 100 mL of water in a olume nts ere pped and weighed empty. These tubes were filled with a specific volume of the slurry a ed with a specific volume of 10,000 or 500 ies d n sodium hydroxide was added to the solution un til it stabilized at a pH value 7.25. The solution was allowed to equili brate overnight before tes ting. The same procedure was repeated using medium anionic polymer instead. 4.6.2 Spike Solutions A 10,00 adding approximately 2.54 grams of solid NaCl vtric flask. A 500 mg/L Na + solution was created daily during sorption experime by adding approximately 1.27 grams solid NaCl pe llets into 1 L of wa ter in a volumetric flask. 10,000 mg/L and 500 mg/L Ca 2+ solutions were also made the same way, but using 2.76 grams and 1.38 grams, respectively, of CaCl 2 pellets instead. 4.6.3 Initial Concentration Spiking and Agitation For a specific slurry (bentonite, bentofix, 1% HC-bentonite, 3% HC-bentonite, 1% MA-bentonite, 3% Ma-bentonite), a set of seven triple rinsed centrifuge tubes w labeled, ca nd weighed again. Th e tubes were spik mg/L of Na or Ca 2+ to create six different initial concentrations of Na + or Ca 2+ and were weighed once more. Calculations for specific volumes for spiking solutions and slurr are included in the Appendix A: Results. Sets of tubes were placed in the tube rotator an were agitated for at least 24 hours. 4.6.4 Quality Control A baseline concentration was establishe d as a quality control measurement in order to account for any leachable sodium or calcium concentrations initially available o 41

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the six slurries. This was accomplished by taking a 5 mL sample from each unexposed slurry, syringe filtering, and pr eserving the sample at 5% HNO 3 Another quality control measure taken dur ing sorption experiments was running blank at the lowest concentra tion of the sorption e a xperiment in order to account for any m or calcium. 4.6.5 S A analysis. This was A) bottle sorption of sodiu ample Preparation 4.6.5.1 Supernatant After agitation, the slurries were placed in a test tube rack and the media settled to the bottom by gravity. Approximately 5 mL of supernatant was carefully extracted from the top of the solution in a centr ifuge tube with a sterile dispos able transfer pipet, placed in a syringe and filtered, and preserved at 5% nitric acid before FA repeated for the rest of the set. 4.6.5.2 Solid Media The final pH of the remaining slurry wa s taken and the slurry was poured into a triple rinsed glass funnel lined with labeled filter paper. Af ter full filtration, the filter paper and extracted media were placed in a drying oven at 50 C for at least three days. After drying, a portion of the filter paper was cut out and placed in a sample bottle for SEM and EDX analysis. 4.7 Sample Analysis 4.7.1 Flame Atomic Adsorption (FA 4.7.1.1 Sodium Blank, 0.1, 0.5, 1, and 1.5 mg/L sodium standa rds were used to create a linear calibration curve during FAA analysis. Sodi um standards were created by spiking a 42

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certain volume of 2 g/L 2% HNO 3 potassium (K + ) matrix modifier with a certain volum of 10,000 mg/L 5% HNO e ifier was created by dissolv lean 1 L volumetric flask and filling the remaining O3 preserved and concentrated supernatants collected from periment s were also diluted with the 2 g/L K+ 2% HNO3 s and 5 mg/L calcium standards were used to create a linear calibrat me % HNO3 solution was created by adding 28.57143 mL of 70% a triple rinsed clean 1 L volumetric flask and filling the remaining and concentrated supernatants collected from desorption, kinetic, and sorption experiment s were also diluted with the 2 g/L K+ 2% HNO3 s 3 Na + standard. The 2 g/L K + matrix mod ing approximately 6.71 gram s of potassium nitrate (KNO 3 ) pellets in 1 L of 2% HNO 3 solution. The 2% HNO 3 solution was created by adding 28.57 mL of 70% concentrated HNO 3 to a triple rinsed c volume with water. 5% HN desorption, kinetic, and sorption ex amples before FAA analysis. Fixed working conditions included a 5 mA lamp current, an air flow of 13.5 L/min and an acetylene flow of 2 L/min. Vari able working conditions were set at a 589 nm wavelength, a 0.5 nm slit width, and the background correction turned on. 4.7.1.2 Calcium Blank, 0.1, 0.5, 1, 3, ion curve during FAA analysis. Calciu m standards were created by spiking a certain volume of 2 g/L 2% HNO 3 potassium (K + ) matrix modifier with a certain volu of 1,000 mg/L 5% HNO 3 Ca 2+ standard. The 2 g/L K + matrix modifier was created by dissolving approximately 6.71865 gram s of potassium nitrate (KNO 3 ) pellets in 1 L of 2% HNO 3 solution. The 2 concentrated HNO 3 to volume with water. 5% HNO 3 preserved amples before FAA analysis. 43

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Fixed working conditions included a 10 mA lamp current, a nitrous oxide (N 2 O) flow of 10.34 L/min and an acetylene flow of 6.55 L/min. Variable working conditions were set at a 422.7 nm wavelength, a 0.5 nm slit width, and the background correction was turned on. 4.7.2 Scanning Electron Microscopy (SEM) A small sample of dried media and filter paper was mounted on top of a piece of carbon tape attached to an aluminum sample holder. No special coatings were used on sample. Pictures were taken on a Hitac the hi S 800 scanning electron microscope at working west possible scan speed and imported into a com puter. Pictures were formatted using EDAX Genesi he l conditions synonymous with high resolution pictures, including the smallest possible working distance, the smallest size aperture setting, the highest possible acceleration voltage (25 kV), and a high c ondenser lens setting. Pictures were taken at the lo s software. 4.7.3 EDX Analysis A small sample of dried media and filter paper was mounted on top of a piece of carbon tape attached to an aluminum sample holder. No special coatings were used on t sample. EDX spectrums were taken using an EDAX detector attached to the SEM. Working conditions used to take spectrums included an acceleration voltage of 25 kV, a 30 tilt, a take off angle of 36.31 and a working distance corresponding to the maximum amount of x-ray counts. The acquisition time for spectrum collection was at least one minute. After the spectrums were collected, peak identification and a percent elementa composition analysis was performed. 44

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CHAPTER FIVE DATA ANALYSIS AND DISCUSSION 5.1 Sorption Experiments Data sets received from AA analysis for samples consisted of initial and final concentrations of sorption experiments. Q the sorption density was calculated from the following equation: ilibrium concentration on the x-axis. l measurements implemented during the experiments are accounted r in t tion of the blank (spiked solution only, no media) sample ran in sorption experiments as reported by the FAA machine (mg/L). Isotherms were constructed with Q (mg/kg), the sorption density, on the y-axis and C e (mg/L), equ M ass M edia Concentrat Aqueous Finalion Concentrat Aqueous Initial SolutionofVolume t MassSorben MassSorbed (* ion ) Quality contro fohe data by implementation of the following equation: Where Final Con = the final calculated concentration (mg/L) accounting for quality control measurements, FAA Final Con = the final concentration of the sorption supernatant reported by the FAA machine (mg/L), Baseline Con=the baseline concentration of the exposed slurry supe rnatant reported by the FAA machine (mg/L), and the Bottle Sorption Con = the amount of bottle sorption that occurred as a difference between the initial and final concentra . . Con Sorption Bottle Con Baseline ConFinalFAAConFinal 45

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5 .1.1 Empirical Isotherm Calculations 5.1.1.1 Linear Isotherm An equation for a linear isotherm was calculated from a lin ear regression of Q and Ce, with the following expression: Q k edC Where C the linear ic plot of Q and Ce, with the following expression: here the slope of the logarithmic linear regr ession is equal to a dimensionless factor nF. and 10y e (mg/L) is proportional to Q (mg/kg) by a factor k d (kg/L). 5.1.1.2 Freundlich Isotherm An equation for a Freundlich isotherm was calculated from regression of the logarithm Q=KFCe nF W -intercept of linear regression is equal to K ([mg] F 1nF [L] nF /kg) 5.1.1.3 Langmuir Isotherm An equation for a Langmuir isotherm was calculated from the linear regression of the plot of 1/ Q and 1/ C e with the following expression: eLCK 1Where (y-intercept of the linear regression) eLmas CKQ Q max* 1 Qslope -1 is equal to Q max (mg/kg) and is equal to K L (L/mg). 46

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5.1.2 Distribution Coefficients Distribution coefficients ( kd, KF, KL) and other constant s calculated for the mpirical For sodium sorption tests, kd distribution coefficients ha d values close in range oefficients varied the smallest valueswith the higher nts had For calcium sorption tests, kd distribution coefficients ranged from about 53 kg/L s had values ranging from 0.03 to 0.0 eisotherms are summarized in Ta bles 5.1 and 5.2 for sodium and calcium sorption tests, respectively. with the exception of the high cationic polymer tests. K F distribution c widely in range. High cationic polymer test s had percentage of cationic polymer resulting in a smaller K F K L distribution coefficie values close in range for all sorption tests. to 130 kg/L. K F distribution coefficients were fairly close in range, with the exception of the 3% high cationic polymer test. K L distribution coefficient 8 L/mg. Table 5.1: Sodium Sorption Test Results EMPIRICAL CONSTANTS LINEAR FREUNDLICH LANGMUIR BATCH TEST kd kg/L nFKF [mg]1-nF[L]nF/kg Qmax mg/kg KL L/mg pH pH INITIAL FINAL Bentonite 1291.7 0.93291654 166666 0.01 6.94 6.96-6.96 Bentofix 1006 0.81872486 200000 0.01 6.94 6.96-6.96 1% High Cationic 725.01 1.1092499 111111 0.02 7.26 6. 72-6.89 3% High 680.76 1.2358244 111111 0.02 6.96 6.72-6.89 Cationic 1% Medium Anionic 1243.6 1.1109712 111111 0.02 7.16 7.04-7.20 3% Medium Anionic 1589.4 1.08691138 200000 0.01 7.07 7.22-7.26 47

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Table 5.2: Calcium Sorption Test Results EMPIRICAL CONSTANTS LINEAR FREUNDLICH LANGMUIR BATCH TEST kg/L[mg]1-nF[L]nF/kg mg/kg L/mg INITIAL FINAL k d n F K F Q max K L pH pH Bentonite 53.873 0.50 221156 16666 0.03 7.02 7.17-7.24 Bentofix 77.63 0.38862912 20000 0.08 6.87 7.15-7.25 1% Hi Cationic gh 89.422 0.50641322 14286 0.05 6.97 7.06-7.27 3% High 130.72 0.8019220 5000 0.06 6.97 6.82-7.15 Cationic 1% Medium Anionic 134.18 0.58731007 12500 0.08 7.22 7.17-7.19 3% Medium Anionic 88.265 0.55891053 12500 0.04 6.92 7.12-7.15 5.1.3 Sorption Isotherm Discussion Empirical equations for Linear, Langmuir and Freundlich isotherms were, with a chosen range of input C values, plotted against the raw values of C and Q This allowed a comparison of how well the empirical isothe rm represented the ra w data and, thus, the accuracy of the fit. e e by usin g to only the three ors ons ent. Analysis of the results reveals thatpirical hae st fit for the data. However, kinetic tests revealed that very litt le socc at g/L or greater for N 0 mg/L for Ca2reticFreunots represent substances that have unlimited sora. Idea consben kite sata wou d an rically calculated Langmothe b all raw e plfor N s equumtration of approximately 50 mg/L and the plateau for the Ca2+ equilibrium concentration begins at approximately 500 mg/L. The best f itting em pirical equations were created g data corr espondin four highe t final concentrati of the experim the em Freundlic h isot erms h d the b rption o urred 50 m a + and 50 + Theo ally, dlich is herm ption c pacity lly, a istency twee netic sts and orption d ld have reveale empi uir is therm as est fit for dataw here th ateau a + begin at an ilibri concen 48

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Inconsistency between kinetic and sorpti on data reveals that another mechanism removed a significant amount of sorbate from the supernatant besi des sorption. Surface precipitation is a very possible mechanism. Although precipitation within the solution was considered in Chapter 4, precipitation fo rming at the surface of the clay was not accounted for. Figdes how surface ptatfluethf strong and weak Langmuir isotherms. ure 5.1 escrib recipi ion in nces e shape o Figure 5.1: (a) Isotherms for Adsorption and Surface Precipitati on Separately (b) Apparent Isotherms for Simultaneous Adso rption and Surface Pr ecipitation (Benjamin, 2002) 49

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Figure 5.2: Multisite Sorpti Competitive t considered before beginning experim pirical single-specie isotherms because oth the species in question. 5.2 SEM Pictures were no significant ch ular bentonite culties g quality resolution pi ctures of the bentonite cl ay above a magnification of 25,000. Another reason for an inaccurate fit of the empirical Langmuir isotherm may be because it is based on a single site type Multisite Langmuir isotherms account for situations were both strong and weak bonding sites influence sorpti on, and the apparent Langmuir isotherm is a result of the sum of two different bonding sites (Figure 5.2). on Isotherm (Benjamin, 2002) sorption between the ions and the polyions was no ents. Isotherms ma y not perfectly fit em er species may have occ upied sites that had a higher affinity than SEM pictures taken at a maximum of ma gnification of 25,000 revealed that there anges in the surfaces or the pores of the exposed reg slurry and the polymer modified bentonite sl urries. Particle chargi ng imposed diffi of takin 50

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5 X Analysis Peak identification of the collected spect rums consisted of using the automa identification feature of the EDAX genesis so ftware and also manually identifying peaks of common elements expected to be s een in the sample. In many cases during .3 ED tic com ma ss action, sodium the peak f ution concentration o sodium (500 pp re n vealed that there was a large increase in the weight percent of comparison to the unexpos ed bentonite powder (0.55%) and sodium was un um in n to the unexposed Bentofix powder (1.09%), and calcium was undetectable indicating the occurren ce of mass action. The Bentofix slurry exposed at the highest positional analysis of the dried slurries exposures of the polymer modified and regular bentonite to high concentrations of s odium or calcium resulted in the principles of ss action, where very high concentrations of a ny type of chemical species is capable of replacing another capable species at a mu ch lower concentration. Through ma a lower valence cation, was able to replace a higher vale nce cation. Mass action occurred in various sample to the point where counts of the replaced ion was so low that or it was unidentifiable. The pure bentonite slurry exposed at the highest sol f m) revealed that there was no change in the weight percent of sodium but the was a small reduction in the weight percent of calcium in comparison to the unexposed bentonite powder. The pure bentonite slurry exposed at the highest solution concentratio of calcium (500 ppm) re calcium (1.56%) in detectable in the exposed sampleindi cating that the process of mass action had likely occurred. The Bentofix slurry exposed at the highe st solution concentration of sodium (500 ppm) revealed that there was a large increase in the weight percent (2.32 %) of sodi compariso 51

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solution concentrati on of calcium (500 ppm) revealed that there was a decrease of calcium r ing, where f the 00 ppm) re vealed that there was a large change in the weight te y weight medium anionic polym er-bentonite slurry exposed at the nic (0.54%) present at the surface in comparison to the unexposed Bentofix powde (1.25%) and sodium was undetectable. The decrease of calcium is not an expected result, and it could be explained by the possibility of an inaccuracy in the EDX sampl the measurement was taken at a location on th e sample where the true composition o exposed slurry was not well represented. This ca n be further attributed to the fact that there is a large jump in the weight pe rcent of carbon (43.02%) from the unexposed Bentofix powder (15.52%)counts coming off of the carbon tape into the EDX detector could have shifted the weight percent composition off. The 3% by weight high cationic polymer-ben tonite slurry expos ed at the highest solution concentration of sodium (5 percent of sodium (2.34%) in co mparison the unexposed bentonite powder (1.09%), and a decrease in the weight percen t of calcium (0.28%) in comparison to the unexposed bentonite powder (0.55%). The 3% by weight high cationic polymer-bentoni slurry exposed at the highest solution concen tration of calcium (500 ppm) revealed that there was a large change in the weight pe rcent of calcium (1.2%) in comparison the unexposed bentonite powder (0.55%), and sodium was undetectable indicating that the process of mass action had likely occurred. The 3% b highest solution concentration of sodium (500 ppm) revealed that there was a moderate change in the weight percen t of sodium (1.92%) in compar ison the unexposed bentonite powder (1.09%), and virtually no change in the weight percent of calcium (0.54%) in comparison to the unexposed bentonite powde r (0.55%). The 3% by weight high catio 52

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polymer-bentonite slurry expos ed at the highest solution c oncentration of calcium ( ppm) revealed that there was a large change in the weight percent of calcium (1.12%) in comparison the unexposed bentonite powder (0.55%), and sodium was undetectable indicating that the pr ocess of mass action had likely occurred. 500 53

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CHAPTER SIX CONCLUSIONS AND RECOMMENDATIONS 6.1 Summary Empirical distribution coefficients for sodium and calcium were extrapolated from Linear, Langmuir, and Freundlich isothe rms models based on resulting data from batch sorption tests of bentonite, a co mmercially manufactured GCL component (Bentofix), a 3% by weight high cationic-bent onite slurry, a 1% by weight high cationicbentonite slurry, a 3% by weight medium an ionic-bentonite slurr y, and a 1% by weight medium anionic-bentonite slurry. Pictures of th e exposed dry slurry surfaces revealed that there was no significant change in comparis on to polymer modified bentonite mixes and natural bentonite. EDX analysis of the e xposed dried slurry surfaces comparison to unexposed bentonite and Bentofix revealed chan ges in weight percentages of sodium and bentonite before and after exposure, indicating mass action had occurred. 6.2 Conclusions The use of high cationic polymers to modify the surfaces of bent onite results in a large reduction of distribution coefficients of linear and Freundlich isotherms in comparison to the other slurries. A reduction in the distribution coefficient results in a smaller Q, sorption density, value at a particul ar equilibrium concentration for both linear and Freundlich isotherms. Therefore, the a ddition of high cationic polymers to the surface 54

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o f bentonite clays results in a negative effect of its sorptive affinity towards sodium and calcium. Modeled Langmuir isotherms for all comparison to the test data. Results from kin very little sorption ccurs for sodium for a con centration of 50 ppm for regular bentonite. These results are with data collected fro m sorption tests, where a reduction in the rface. EDX in the weight measured at th e surface after exposure to a 500 ppm Na+ solution in ompar er sorption tests revealed a poor fit in e tic tests reveal that o not in harmony concentration is seen even at an initial concentrat ion of 500 ppm. This could be due to fact that a conventional singl e-site, single-species Langmuir isotherm may not represent the data well if there is multi-site and comp etitive sorption occurring at the clay su Polymer modification of bentonite at 1 a nd 3% by weight results in very little change of the physical appearance of the surface of the clays as seen by a scanning electron microscope up to a magnification of 25,000. Polymer modified bentonite samples as well as regular sodium bentonite experienced an increase in the weight percen t of calcium measured at the surface by analysis after exposure to a 500 ppm Ca 2+ solution. However, polymer modified bentonite samples, with the ex ception of Bentofix, experienced an increase percent of sodium cison to sodium bentonite, which had no change in percent by weight sodium present at the surface after the same expos ure. EDX analysis suggests that polym modified bentonite is a better sorbent for sodium than sodium bentonite, but polymer modified bentonite and sodium bentonite are both effective sorbents for calcium. 55

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6.3 Recommendations Re sults of this research may be used for modeling applications to characterize ntrations tions for ay hus increasing the presence of sorbent elative this GCL performance in the presence of inorganic leachates that contain high conce of sodium and calcium. With a distribution coefficient and other relevant parameters pertaining to the properties of the clay compone nt of the GCL, it is possible to model the contaminant transport equation and the con centration history assuming condi equilibrium are present. In order to correctly predict GCL perfor mance from results of lab-scale batch sorption studies one must keep in mind th at lab-scale batch sorption studies are performed with a high ratio of concentrated sorbate (calcium or sodium) to sorbent (cl component). For most engineering applicati ons of GCLs in landfills, it is just the opposite: there is a high ratio of adsorbent to sorbate. T in comparison to the sorbate increases the sorptive potential of the GCL r to all sorbates. Another consideration during modeling is that distribution coefficients in research were extrapolated from single-species, single-site isotherm models. It is highly unlikely that inorganic leachates will contain only sodium or calcium, and competing ions may increase or decrease the affinity of the clay surface for a certain chemical species. 56

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York, New York, 1989. Ashmawy, A.K., El-Hajji, D., Sotelo, N ., and Muhammad, N. (2002) Hydraulic Leachates, Clay and Cla REFERENCES Alger, M.S.M. Polymer Science Dictionar y, Elsevier Science Publishers Ltd., New Performance of Untreated and Polymer-Treated Bentonite in Inorganic Landfill y Minerals Vol. 50, No. 5, pp. 546-552. Benjam Education, Singapore, 2002. Ebdon, L., Evans, E.H., Fisher, A., Hill, S. J., An Introduction to Analytical Atomic nic Leachate on Polymer Treated GCL Material, Proceedings of the Geosynthetics 2001 EPA530-F-97-002. Washington, D.C. Goldstein, J. Scanning Electron Microsc opy and X-Ray Analysis, Second Edition, lenum Prentice Hall, Upper Saddle River, New Jersey, 1999. Lawes, G. Scanning Electron Microscopy a nd X-Ray Analysis, John Wiley and Sons, J.K. Fundamentals of Soil Behavi or, Second Edition, John Wiley and Sons, Inc. New York, New York, 1993. Petrov, R.J., Rowe, R.K. and Quigley, R. M. (1997) Comparison of LaboratoryMeasured GCL Hydraulic Conductivity Based on Three Parameter Types, Geotechnical Testing Journal Vol. 20, No. 1, pp. 49-62. Shackelford, C.D., Benson, C.H., Katsumi, T., Edil, T.B. and Lin, L. (2000) Evaluating the Hydraulic Conductivity of GCLs pe rmeated with non-standard liquids, Geotextiles and Geomembranes 18, pp. 133-161. in, M.M. Water Chemistry, In ternational Edition, McGraw-Hill Higher Spectrometry, John Wiley and Sons, New York, New York, 1998. Elhajji, D., Ashmawy, A.K., Darlington, J. a nd Sotelo, N. (2001) Effect of Inorga Conferences, Portland, Oregon, pp. 663-670. EPA (2001) Geosynthetic Clay Liners Us ed in Municipal Solid Waste Landfills. P Press, New York, 1992. Hill, J. W., Petrucci, R.H. General Chemis try an Integrated Approach, Second Edition, New York, New York, 1987. Mitchell, 57

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Schenning, Jessica. (2004) Hydr aulic Performance of Poly mer Modified Bentonite, University of South Florida. Tampa, Fl. Theng, B.K.G. Formation and Properties of lay-Polymer Complexes, Elsevier Scientific Publishing Company, New 1979. n, pper Saddle River, New Jersey, 2005. C York, New York Viessman, W.J., Hammer, M.J. Water Supply and Pollution Control, Seventh Editio Pearson Education, Inc, U 58

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APPENDICES 59

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Appendix A: Results Table A.1: Desorption Tests DATE TIME SAMPLE pH INITIAL ACID/BASE pH TEMP 4/5 9:33 1 9:50 2 10:01 6.23 HNO3 10L 10:15 3 10:30 6.87 10:43 4 10:55 7.95 HNO3 10L 11:36 5 11:48 6.64 NaOH 10L 22.4oC 12:16 7.94 HNO3 10L 7.38 22.2oC 12:19 6.77 NaOH 20L 6.62 22.2oC 1:40 6 8.43 HNO3 20L 3:16 6.20 NaOH 10L 6.41 21.5oC 3:39 7 3:50 6.31 NaOH 10L 6.41 21.5oC 4:51 6.94 NaOH 10L 6.34 21.5oC 5:09 6.60 NaOH 20L 5:17 8 5:24 NaOH 20L 6.67 6.63 6:56 6.68 NaOH 30L 6.74 4/6 10:33 9 7.11 3:16 10 6.86 NaOH 10L 6.88 21.4oC 6:37 7.4 4/7 12:29 6.97 12:45 11 7.07 60

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Appendix A: ( Continued) Sodium Des tio.4568 R2 = 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 00.20.40 0.8 Sooncentration orption Calibra n Curve y = 0 9x + 0.262 .9998 .6 11.2 1.4 1.6 dium C (ppm) Ab sorb an ce S tandard Linear (S tandard) Figure A.1: FAA Calibration Cu rve for Sodium Desor ption S odium D esorption 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 0.00 10.0020.0030.0040.0050.0060.00 Time (hours)Concentration) (ppm Figure A.2: Sodium Desorption Curve 61

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Appendix A: (Continued) Calcium Desorption Calibration Curvey = 0.1929x + 0.0069 R2 = 0.9957 0 0.2 0.4 0.6 0.8 1 1.2 012345 Sodium Concentration (ppm)Absorbance 6 Standard Linear (Standard) Calcium Concentration (ppm) Figure A.3: FAA Calibration Cu rve for Calcium Desorption Calcium Desorption -0.20 0.00 0.20 0.40 0.60 0.80 1.00 0.00 5.0010.0015.0020.0025.0030.00 Time (hours)Concentration (ppm) Figure A.4: Calcium Desorption Curve 62

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Appendix A: (Continued) Table A.2: Na+ 500 ppm Kinetic Test DATE TIME SAMPLE pH INITIAL ACID/BASE pH TEMP 4/5 9:33 1 9:50 2 10:01 7.37 HNO3 10L 10:15 3 7.05 10:41 4 10:55 7.41 HNO3 10L 11:36 5 11:48 7.03 22.1oC 12:11 7.12 HNO3 10L 7.07 22oC 12:26 7.31 HNO3 10L 6.52 12:29 L 21.0oC 6.49 NaOH 20 1:38 6 6.71 NaOH 10L 3:39 7 3:55 7.10 21.3oC 4:45 7.14 HNO 3 10L 7.05 5:17 8 6:59 7.01 4/6 10:33 7.17 HNO3 10L 7.05 3:22 10 6.97 6:32 7.13 HNO3 10L 6.71 21.3oC 4/7 12:38 11 63

PAGE 81

Appendix A: (Continued) Sodium 5 0 0 ny79x = 0 0 0.2 0.4 0.6 0.8 1 2 0 0.40.0.8 .4 6 Sooncentration ppm Calibratio Curve = 0.4 R2 + 0.2628 .9969 1. 0.2 6 11.2 1 1. dium C (ppm) Ab sorb an ce Sard tand Linear (Sd) tandar Figure A.5: FAA Calibration Curve for Sodium 500 pp m Kinetic Test Na Kinetics : 500 ppm 0.00 100.00 200.00 300.00 400.00 .00 600.00 0.00 10.0020.0030.0040.0050.0060.00 Time (hours)Concentration (ppm) 500 Figure A.6: Sodium 500 ppm Kinetic Test 64

PAGE 82

Appendix A: (Continued) Table A.3: Na+ 50 ppm Kinetic Test DATE TIME SAMPLE pH INITIAL ACID/BASE pH TEMP 4/13 1:12 1 2.45 1:37 2 2.57 NaOH 20L 1:45 2.57 NaOH 3000L 2:16 3 6.81 HNO3 10L 6.49 NaOH 100L 2:28 6.51 NaOH 70L 6.65 2:50 4 6.69 NaOH 20L 6.74 23.2oC 2:59 6.73 NaOH 20L 6.77 3:47 5 6.74 NaOH 20L 6.75 23.2oC 4:26 6.82 NaOH 20L 6.83 23.1oC 5:00 6.81 NaOH 40L 6.96 5:32 6.90 NaOH 20L 6.92 23oC 5:33 6 6.92 NaOH 20L 6.93 23oC 6:18 6.89 NaOH 20L 6.92 22.9oC 7:47 7 6.89 NaOH 20L 6.9 1 22.7oC 4/14 11:16 8 6.77 NaOH 20L 6.74 11:30 6.77 NaOH 50L 6.90 22.1oC 3:18 9 6.86 NaOH 20L 22.1oC 5:13 10 6.89 NaOH 20L 6.91 4/15 1:10 11 6.88 NaOH 20L 22.9oC 65

PAGE 83

Appendix A: (Continued) Sod ium 50 ppm Calib rat = 0492 = 0.8655 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 00.20.4 0.8 1.2 1.6 m Concentra ion Curve y 0.5764x + 0. R 1 0.6 1 1.4 Sodiu tion (ppm) Ab sorb an ce Standar d Lin ear (Standard) Fure A. Calibran Curv Sodium 50 Tes ig 7: FAA tio e for ppm Kinetic t Na K inetics: 50 p 0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 0 100.0 0.0010.0020.0030.0040.0050.0060.00 Time (hours)Concentration (ppm) pm 90. 0 0 Figure A.8: Sodium 50 ppm Kinetic Test 66

PAGE 84

Appendix A: (Continued) Table A.4: 500 Ca2+ ppm Kinetic Test DATE TIME SAMPLE pH INITIAL ACID/BASE pH TEMP 4/5 9:33 1 9:50 2 10:01 6.64 10:15 3 10:30 6.5 10:41 4 10:55 7.40 HNO3 10L 11:36 5 11:48 6.41 NaOH 10L 6.75 22.2oC 12:14 6.64 NaOH 10L 6.89 22.1oC 12:23 6.99 1:39 6 7.30 HNO3 10L 3:39 7 21.4oC 21.4o 3:52 6.82 C 7.03 21.3oC 4:45 7.24 HNO 3 10L 5:17 8 5:58 6.44 4/6 10:33 9 7.35 HNO3 10L 7.25 21.7oC 3:21 10 7.22 HNO3 10L 6.32 6.92 HNO3 10L 4/7 12:29 11 7.26 HNO3 20L 6.64 22.1oC 67

PAGE 85

Appendix A: (Continued) Calcium 5 00 ppm Calibratio ny = 0. + 0.0069 9957 0 0.2 0.4 0.6 0.8 1 2 0123 Soncentration Curve 1929x R2 = 0. 1. 4 5 6 dium Co (ppm) Ab sorb an ce S tandard Linear (Sndard) ta Figure A.9: FAA Calibration Curve for Calcium 500 p st pm Kinetic Te Calcium 500 p pm Kinetic Te 0.00 100.00 200.00 300.00 400.00 00.00 600.00 0.00 10.0020.0030.0040.0050.0060.00 Time (hours)Concentration (ppm) st 5 Figure A.10: Calcium 500 ppm Kinetic Test 68

PAGE 86

Appendix A: (Continued) Table A.5: Spike Calculations for Sodium Sorption Experiments STOCK SOLUTION CONCENTRATION (mg/L) FINAL SAMPLE CONCENTRATION (mg/L) FINAL SAMPLE VOLUME (mL) SLURRY STOCK VOLUME SPIKE (mL) VOLUME (mL) 10000 500.00 30 28.500 1.500 10000 100.00 30 29.700 0.300 10000 50.00 30 29.850 0.150 10000 10.00 30 29.970 0.030 500 1.00 30 29.940 0.060 500 0.20 30 29.990 0.010 500 0.20 30 29.990 0.010 Table A.6: Spike Calculations for Calcium Sorption Experiments STOCK SOLUTION CONCENTRATION (mg/L) FINAL SAMPLE CONCENTRATION (mg/L) FINAL SAMPLE VOLUME (mL) SLURRY VOLUME STOCK SPIKE (mL) VOLUME (mL) 10000 500.00 25 23.750 1.250 10000 100.00 25 24.750 0.250 10000 50.00 25 24.875 0.125 10000 10.00 25 24.975 0.025 500 1.00 25 24.950 0.050 500 0.20 25 24.990 0.010 500 0.20 25 24.990 0.010 69

PAGE 87

Appendix A: (Continued) Sod ium Sorlib ption Ca ration y = 0.6362x + 0.055 R2 = 0.9307 0 0.2 0.4 0.6 0.8 0 0.4 0. 1.21.41.6 um Concetion (pAbsorban 1 1.2 0.2 0.6 8 1 Sodi ntra pm) c Standard Linear (Standard) Absorbance FiguA Calibrae for Sr re A.11: FA tion Curv odium So ption Sodium Calibration-Baseline Samples Onlyy = 0.5872x + 0.0524 R2 = 0.9458 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 00.20.40.60.811.21.41.6 Sodium Concentration (ppm)Absorban c Series1 Linear (Series1) Absorbance Figure A.12: FAA Calibration Curve Sodium Baseline Samples 70

PAGE 88

Appendix A: (Continued) Linear Isotherm-Bentonite Nay = 1291.7x R2 = 0.9911 -5.0E+04 0.0E+00 5.0E+04 0E+05 5E+05 2.0E+05 2.5E+05 0.0020.0040.0060.0080.00100.00120.00140.00160.00180.00 Ce Na (mg/L) 1. 1.Q(mg/kg) ` Figure A.13: Linear Isotherm-Bentonite Na Q(mg/kg) 71

PAGE 89

Appendix A: (Continued) Freundlich Isotherm Estimation-Bentonite Nay = 0.9329x + 3.2186 R2 = 0.9584 0.00 1.00 2.00 3.00 4.00 5.00 6.00 0.00 0.50 1.00 1.50 2.00 2.50 log(Ce Na) [log(m g/L)]log(S) [log(mg / nF=0.9329 KF=103.2186=1654 S=1654C0.9329 Log(Qg]) )(log[mg/k Figure A.14: Freundlich Isothe rm Estimation -Bentonite Na Freundlich Isotherm-Bentonite Na-5.0E+04 0.0E+00 5.0E+04 1.0E+05 1.5E+05 2.0E+05 2.5E+05 0.0020.0040.0060.0080.00100.00120.00140.00160.00180.00Ce Na (m g/L)Q(mg/ kg Plotted Data Empirical Isotherm Figure A.15: Freundlich Is otherm-Bentonite Na Q(mg/kg) 72

PAGE 90

Appendix A: (Continued) Langmuir Isotherm Estimation-Bentonite Na y = 0.0006x + 6E-06 R2 = 0.9116 0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05 2.5E-05 3.0E-05 3.5E-05 4.0E-05 4.5E-05 5.0E-05 00.010.020.030.040.050.060.070.08 1/Ce Na (mg/L)1/(mass sorbed/sorbent) 1/( m 1/Smax=6E-6, Sm ax=166666 KL= 1/(Slope*Sm ax)=0.01 S=166666*(0.01C)/(1+0.01C) 1/(mass sorbed/sorbent)[1/(mg/kg)] Figure A.16: Langmuir Isotherm Estimation-Bentonite Na Langmuir Isotherm-Bentonite Na0.0E+00 5.0E+04 1.0E+05 1.5E+05 2.0E+05 2.5E+05 0.0020.0040.0060.0080.00100.00120.00140.00160.00180.00Ce Na (m g/L)Q(mg/ kg Plotted Data Empirical Isotherm Q(mg/kg) Figure A.17: Langmuir Isotherm-Bentonite Na 73

PAGE 91

Appendix A: (Continued) Linear Isotherm-Bentofix Nay = 1006x R2 = 0.9923 0. 0E+0 0E 0E 0E 0E 0E 2E 4E 6E+ 8E+0 0 2.+04 4.+04 6.+04 8.+04 1.+05 1.+05 1.+05 1.05 1.5 2.0E+05 0.0020.0040.0060.0080.00100.00120.00140.00160.00180.00200.00 Ce Na (mg/L)Q(mg/kg) Q(mg/kg) Q(mg/kg) ` Figure A.18: Linear Isotherm-Bentofix Na 74

PAGE 92

Appendix A: (Continued) Freundlich Isotherm Estimation-Bentofix Nay = 0.8187x + 3.3955 R2 = 0.9929 0.00 1.00 2.00 3.00 4.00 5.00 6.00 0.00 0.50 1.00 1.50 2.00 2.50 log(Ce Na) [log(m g/L)]log(S) [log(mg / nF=0.8187 KF=103.3955=2486 S=2486C0.8187 Log(Q) ]) (log[mg/kg Figure A.19: Freundlich Isothe rm Estimatio n-Bentofix Na Freundlich Isotherm-Bentofix Na-5.0E+04 0.0E+00 5.0E+04 1.0E+05 1.5E+05 2.0E+05 0.0020.0040.0060.0080.00100.00120.00140.00160.00180.00200.00Ce Na (m g/L)Q(mg/ kg Plotted Data Empirical Isotherm Figure A.20: Freundlich Isotherm-Bentofix Na Q(mg/kg) 75

PAGE 93

Appendix A: (Continued) Langmuir Isotherm Estimation-Bentofix Na y = 0.0006x + 5E-06 R2 = 0.9703 0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05 2.5E-05 3.0E-05 3.5E-05 4.0E-05 4.5E-05 5.0E-05 00.010.020.030.040.050.060.070.08 1/Ce Na (mg/L)1/(m ass sorbed/sorbent) 1/ ( m S=200000*(0.01C)/(1+0.01C) 1/Sm ax=5E-6, Smax=200000 KL= 1/(Slope*Smax)=0.01 nt)[1/(mg/kg)] 1/(mass sorbed/sorbe Figure A.21: Langmuir Isotherm Estimation-Bentofix Na Langmuir Isotherm-Bentofix Na0.0E+00 2.0E+04 4.0E+04 6.0E+04 8.0E+04 1.0E+05 1.2E+05 1.4E+05 1.6E+05 1.8E+05 2.0E+05 0.0020.0040.0060.0080.00100.00120.00140.00160.00180.00200.00Ce Na (mg/L)Q(mg/ kg Plotted Data Empirical Isotherm Q(mg/kg ) Figure A.22: Langmuir Isotherm-Bentofix Na 76

PAGE 94

Appendix A: (Continued) Linear Isotherm-1% HC Nay = 725.01x R2 = 0.9917 0.0E+00 2.0E+04 4.0E+04 6.0E+04 8.0E+04 1.0E+05 1.2E+05 1.4E+05 1.6E+05 1.8E+05 0.00 50.00 100.00 150.00 200.00 250.00 Ce Na (mg/L)Q(mg/kg) ` Q(mg/kg) Figure A.23: Linear Isotherm-1% HC Na 77

PAGE 95

Appendix A: (Continued) Freundlich Isotherm Estimation-1% HC Nay = 1.1092x + 2.6977 R2 = 0.8875 0.00 1.00 2.00 3.00 4.00 5.00 6.00 0.00 0.50 1.00 1.50 2.00 2.50 log(Ce Na) [log(m g/L)]log(S) [log(mg / nF=1.1092 KF=102.6977=499 S=499C1.1092 Log(Q)(log[mg/kg]) Figure A.24: Freundlich Isothe rm Estimati on-1% HC Na Freundlich Isotherm-1% HC Na-5.0E+04 0.0E+00 5.0E+04 1.0E+05 1.5E+05 2.0E+05 2.5E+05 0.00 50.00100.00150.00200.00250.00 Ce Na (mg/L)Q(mg/k g Plotted Data Empirical Isotherm Figure A.25: Freundlich Isotherm-1% HC Na Q(mg/kg) 78

PAGE 96

Appendix A: (Continued) Langmuir Isotherm Estimation-1% HC Nay = 0.0006x + 9E-06 R2 = 0.8864 0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05 2.5E-05 3.0E-05 3.5E-05 4.0E-05 4.5E-05 5.0E-05 00.010.020.030.040.050.060.0 1/Ce Na (mg/L)1/(m 7 ass sorbed/sorbent) 1/( S=111111*(0.02C)/(1+0.02C) 1/Sm ax=9E-6, Sm ax=111111 KL= 1/(Slope*Sm ax)=0.02 1/(mass so )] rbed/sorbent)[1/(mg/kg Figure A.26: Langmuir Isotherm Estimation-1% HC Na Langmuir Isotherm-1% HC Na0.0E+00 2.0E+04 4.0E+04 6.0E+04 8.0E+04 1.0E+05 1.2E+05 1.4E+05 1.6E+05 1.8E+05 0.0050.00100.00150.00200.00250.00Ce Na (mg/L) Q(mg/ kg Plotted Data Empirical Isotherm mg/kg) Q( Figure A.27: Langmuir Isotherm-1% HC Na 79

PAGE 97

Appendix A: (Continued) Linear Isotherm-3% HC Nay = 680.76x R2 = 0.9947 0.0E+00 2.0E+04 4.0E+04 6.0E+04 8.0E+04 1.0E+05 1.2E+05 1.4E+05 1.6E+05 0.00 50.00 100.00 150.00 200.00 250.00 Ce Na (mg/L)Q(mg/kg) ` Q(mg/kg) Figure A.28: Linear Isotherm-3% HC Na 80

PAGE 98

Appendix A: (Continued) Freundlich Isotherm Estimation-3% HC Nay = 1.2358x + 2.3878 R2 = 0.8816 0.00 1.00 2.00 3.00 4.00 5.00 6.00 0.00 0.50 1.00 1.50 2.00 2.50 log(Ce Na) [log(m g/L)]log(S) [log(mg / nF=1.2358 KF=102.3878=244 S=244C1.2358 Log(Q)(lo g[mg/kg]) Figure A.29: Freundlich Isothe rm Estimati on-3% HC Na Freundlich Isotherm-3% HC Na-5.0E+04 0.0E+00 5.0E+04 1.0E+05 1.5E+05 2.0E+05 2.5E+05 0.00 50.00100.00150.00200.00250.00Ce Na (mg/L)Q(mg/ kg Plotted Data Empirical Isotherm Figure A.30: Freundlich Isotherm-3% HC Na Q(mg/kg) 81

PAGE 99

Appendix A: (Continued) Langmuir Isotherm Estimation-3% HC Nay = 0.0008x + 9E-06 R2 = 0.871 0.0E+00 1.0E-05 2.0E-05 3.0E-05 4.0E-05 5.0E-05 6.0E-05 00.010.020.030.040.050.06 1/Ce Na (mg/L)1/(mass sorbed/sorbent) 1/( 1/Sm ax=9E-06, Sm ax=111111 KL= 1/(Slope*Sm ax)=0.02 S=111111*(0.02C)/(1+0.02C) 1/(mass so nt)[1/(mg/kg)] rbed/sorbe Figure A.31: Langmuir Isotherm Estimation-3% HC Na Langmuir Isotherm-3% HC Na0.0E+00 2.0E+04 4.0E+04 6.0E+04 8.0E+04 1.0E+05 1.2E+05 1.4E+05 1.6E+05 0.00 50.00100.00150.00200.00250.00Ce Na (m g/L)Q(mg/ kg Plotted Data Empirical Isotherm Q(mg/kg) Figure A.32: Langmuir Isotherm-3% HC Na 82

PAGE 100

Appendix A: (Continued) Linear Isotherm-1% MA Nay = 1243.6x R2 = 0.9871 0.0E+00 5.0E+04 1.0E+05 1.5E+05 2.0E+05 2.5E+05 0.0020.0040.0060.0080.00100.00120.00140.00160.00180.00 Ce Na (mg/L)Q(mg/kg) ` Q(mg/kg) Figure A.33: Linear Isotherm-1% MA Na 83

PAGE 101

Appendix A: (Continued) Freundlich Isotherm Estimation-1% MA Nay = 1.1109x + 2.8527 R2 = 0.9278 0.00 1.00 2.00 3. 4. [log(mg 00 00 5.00 6.00 0.00 0.50 1.00 1.50 2.00 2.50 log(Ce Na) [log(mg/L)]log(S) / nF=1.1109 KF=102.8527=712 S=712C1.1109n-1% MA Na Log(Q)g]) (log[mg/k Figure A.34: Freundlich Isothe rm Estimatio Freundlich Isotherm-1% MA Na-5.0E+04 0.0E+00 5.0E+04 1.0E+05 1.5E+05 2.0E+05 2.5E+05 0.0020.0040.0060.0080.00100.00120.00140.00160.00180.00Ce Na (m g/L)Q(mg/ kg Plotted Data Empirical Isotherm Figure A.35: Freundlich Isotherm-1% MA Na Q(mg/kg) 84

PAGE 102

Appendix A: (Continued) Langmuir Isotherm Estimation-1% MA Nay = 0.0005x + 9E-06 R2 = 0.7696 0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05 2.5E-05 3.0E-05 3.5E-05 4.0E-05 4.5E-05 00.010.020.030.040.050.060.070.08 1/Ce Na (m g/L)1/( mass sorbed/sorbent) 1/( S=111111*(0.02C)/(1+0.02C) 1/Sm ax=9E-6, Smax=111111 KL= 1/(Slope*Smax)=0.02 1/(mass so nt)[1/(mg/kg)] rbed/sorbe Figure A.36: Langmuir Isotherm Estimation-1% MA Na Langmuir Isotherm-1% MA Na0.0E+00 5.0E+04 1 1Q(mg/ .0E+05 .5E+05 2.0E+05 2.5E+05 0.0020.0040.0060.0080.00100.00120.00140.00160.00180.00Ce Na (mg/L) kg Plotted Data Empirical Isotherm Q(mg/kg) Figure A.37: Langmuir Isotherm 1% MA Na 85

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Appendix A: (Continued) Linear Isotherm-3% MA Nay = 1589.4x R2 = 0.9975 0.0E+00 5.0E+04 1.0E+05 1.5E+05 2.0E+05 2.5E+05 0.0020.0040.0060.0080.00100.00120.00140.00160.00 Ce Na (mg/L)Q(mg/kg) ` Q(mg/kg) Figure A.38: Linear Isotherm-3% MA Na 86

PAGE 104

Appendix A: (Continued) Freundlich Isotherm Estimation-3% MA Nay = 1.0869x + 3.0563 R2 = 0.9532 0.00 1.00 2.00 3.00 4.00 5.00 6.00 0.00 0.50 1.00 1.50 2.00 2.50 log(Ce Na) [log(m g/L)]log(S) [log(mg / nF=1.0869 KF=103.0563=1138 S=1138C1.0869 Log(Q)(lo]) g[mg/kg Figure A.39: Freundlich Isothe rm Estimatio n-3% MA Na Freundlich Isotherm-3% MA Na0.0E+00 5.0E+04 1.0E+05 1.5E+05 2.0E+05 2.5E+05 3.0E+05 0.0020.0040.0060.0080.00100.00120.00140.00160.00Ce Na (m g/L)Q(mg/ kg Plotted Data Empirical Isotherm Figure A.40: Freundlich Isotherm-3% MA Na Q(mg/kg) 87

PAGE 105

Appendix A: (Continued) Langmuir Isotherm Estimation-3% MA Na y = 0.0004x + 5E-06 R2 = 0.9341 0.0E+00 5.0E-06 1.0E-05 1.5E-05 2.0E-05 2.5E-05 3.0E-05 3.5E-05 4.0E-05 00.010.020.030.040.050.060.070.080.09 1/Ce Na (mg/L)1/(m ass sorbed/sorbent) 1/ ( m S=200000*(0.01C)/(1+0.01C) 1/Smax=5E-6, Sm ax=200000 KL= 1/(Slope*Sm ax)=0.01 1/(mass so nt)[1/(mg/kg)] rbed/sorbe Figure A.41: Langmuir Isotherm Estimation-3% MA Na Langmuir Isotherm-3% MA Na0.0E+00 5.0E+04 1.0E+05 1.5E+05 2.0E+05 2.5E+05 0.0020.0040.0060.0080.00100.00120.00140.00160.00 Ce Na (mg/L)Q(mg/k g Plotted Data Empirical Isotherm Q(mg/kg ) Figure A.42: Langmuir Isotherm-3% MA Na 88

PAGE 106

Appendix A: (Continued) Calcium Sorption Calibration (500, 100, and 10 samples) y = 0.1883x + 0.0497 R2 = 0.9784 0 0.2 0.4 0.6 0.8 1 1.2 012345 Sodium Concentration (ppm) Absorban c 6 Standard Linear (Standard) Absorbance Figure A.43: FAA Calibration Curve for Ca lcium Samples 500 ppm, 100 ppm, and 10 ppm Initial Concentrations Calcium Sorption Calibration (50, 1, .1, baseline and blank samples) y = 0.209x + 0.0177 R2 = 0.9962 0 0.2 0.4 0.6 0.8 1 1.2 0123456 Sodium Concentration (ppm)Absorban c Standard Linear (Standard) Abs orbance Figure A.44: FAA Calibration Curve for Ca lcium Samples 50 ppm, 1 ppm, and 0.1 ppm Initial Concentrations 89

PAGE 107

Appendix A: (Continued) Linear Isotherm-Bentonite Cay = 53.873x R2 = 0.6387 0.0E+00 5.0E+03 1.0E+04 1. 2.Q(mg/kg) 5E+04 0E+04 2.5E+04 Ce Ca (mg/L) 0.0050.00100.00150.00200.00250.00300.00350.00400.00450.00 Q(mg/kg) -Bentonite Ca Figure A.45: Linear Isotherm 90

PAGE 108

Appendix A: (Continued) Freundlich Isotherm Estimation-Bentonite Ca y = 0.5022x + 3.063 R2 = 0.9557 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 0.000.501.001.502.002.503.00 log(Ce C a) [log(mg/L)]log(S) [log(mg/ k nF=0.5022 KF=103.063=1156 S=1156C0.5022 Figure A.46: Freundlich Isothe rm Estimation-Bentonite Ca Log(Q ]) )(log[mg/kg Freundlich Isotherm-Bentonite Ca0.0E+00 5.0E+03 1.0E+04 1.5E+04 2.0E+04 2.5E+04 3.0E+04 0.0050.00100.00150.00200.00250.00300.00350.00400.00450.00Ce Ca (m g/L)Q(mg/ kg Plotted Data Empirical Isotherm Figure A.47: Freundlich Is otherm-Bentonite Ca Q(mg/kg) 91

PAGE 109

Appendix A: (Continued) Langmuir Isotherm Estimation-Bentonite Ca y = 0.0021x + 6E-05 R2 = 0.9841 0.0E+00 5.0E-05 1.0E-04 1.5E-04 2.0E-04 2.5E-04 3.0E-04 3.5E-04 4.0E-04 4.5E-04 00.020.040.060.080.10.120.140.160.18 1/Ce Ca (mg/L)1/(mass sorbed/sorbent) 1/( m 1/Smax=6E-5, Smax=16666 KL= 1/(Slope*Smax)=0.03 S=16666*(0.03C)/(1+0.03 C ) 1/(mass sorbed/sorbent)[1/(mg/kg)] Figure A.48: Langmuir Isotherm Estimation-Bentonite Ca Langmuir Isotherm-Bentonite Ca0.0E+00 5.0E+03 1.0E+04 1.5E+04 2.0E+04 2.5E+04 0.0050.00100.00150.00200.00250.00300.00350.00400.00450.00Ce Ca (m g/L) kg / Q(mg Plotted Data Empirical Isotherm Q(mg/ kg) Figure A.49: Langmuir Isotherm-Bentonite Ca 92

PAGE 110

Appendix A: (Continued) Linear Isotherm-Bentofix Cay = 77.63x R2 = 0.6391 -5 .0E+ .0E+ .+ .+ .+ .+ .+ .0E+ 03 000 50E03 10E04 15E04 20E04 25E04 304 3.5E+04 0.0050.00100.00150.00200.00250.00300.00350.00400.00450.00 Ce Ca (mg/L)Q(mg/kg) Q(mg/kg) ` Figure A.50: Linear Isotherm-Bentofix Ca 93

PAGE 111

Appendix A: (Continued) Freundlich Isotherm Estimation-Bentofix Cay = 0.3886x + 3.4642 R2 = 0.9933 0.00 0.50 1.00 1.50 2.00 2 3 3 .50 .00 .50 4.00 4.50 5.00 0.000.501.001.502.002.503.00 log(Ce Ca) [log(m g/L)]log(S) [log(mg / nF=0.3886 KF=103.4642=2912 S=2912C0.3886n-Bentofix Ca Log(Q)g]) (log[mg/k Figure A.51: Freundlich Isothe rm Estimatio Freundlich Isotherm-Bentofix Ca-5.0E+03 0.0E+00 5.0E+03 1.0E+04 1.5E+04 2.0E+04 2.5E+04 3.0E+04 3.5E+04 0.0050.00100.00150.00200.00250.00300.00350.00400.00450.00Ce Ca (m g/L)Q(mg/ kg Plotted Data Empirical Isotherm Figure A.52: Freundlich Isotherm-Bentofix Ca Q(mg/kg) 94

PAGE 112

Appendix A: (Continued) Langmuir Isotherm Estimation-Bentofix Ca y = 0.0006x + 5E-05 R2 = 0.9459 0.0E+00 5.0E-05 1.0E-04 1.5E-04 2.0E-04 2.5E-04 00.050.10.150.20.250.3 1/Ce Ca (mg/L)1/( masbent) 1/ s sorbed/sor( m S=20000*(0.08C)/(1+0.08C) 1/Sm ax=5E-5, Smax=20000 KL= 1/(Slope*Smax)=0.08 1/(mass sorbnt)[1/(mg/kg)] ed/sorbe Figure A.53: Langmuir Isotherm Estimation-Bentofix Ca Langmuir Isotherm-Bentofix Ca0.0E+00 5.0E+03 1.0E+04 1.5E+04 2.0E+04 2.5E+04 3.0E+04 3.5E+04 0.0050.00100.00150.00200.00250.00300.00350.00400.00450.00Ce Ca (mg/L) Q(mg/ kg Plotted Data Empirical Isotherm Q(mg/kg ) Figure A.54: Langmuir Isotherm-Bentofix Ca 95

PAGE 113

Appendix A: (Continued) Linear Isotherm-1% HC Cay = 89.422x R2 = 0.9233 0.0E+00 5.0E+03 1.0E+04 1.5E+04 2.0E+04 2.5E+04 3.0E+04 3.5E+04 4.0E+04 0.0050.00100.00150.00200.00250.00300.00350.00400.00450.00 Ce Ca (mg/L)Q(mg/kg) ` Q(mg/kg) Figure A.55: Linear Isotherm-1% HC Ca 96

PAGE 114

Appendix A: (Continued) Freundlich Isotherm Estimation-1% HC Cay = 0.5064x + 3.1213 R2 = 0.8276 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 0.000.501.001.502.002.503.00 log(Ce Ca) [log(mg/L)] log( S nF=0.5064 KF=103.1213=1322 S=1322C0.5064on-1% HC Ca Log(Q ]) )(log[mg/kg Figure A.56: Freundlich Isothe rm Estimati Freundlich Isotherm-1% HC Ca0.0E+00 5.0E+03 1.0E+04 1.5E+04 2.0E+04 2.5E+04 3.0E+04 3.5E+04 4.0E+04 0.0050.00100.00150.00200.00250.00300.00350.00400.00450.00 Ce Ca (mg/L)Q(mg/k g Plotted Data Empirical Isotherm Figure A.57: Freundlich Isotherm-1% HC Ca Q(mg/kg) 97

PAGE 115

Appendix A: (Continued) Langmuir Isotherm Estimation-1% HC Cay = 0.0013x + 7E-05 R2 = 0.8479 0.0E+00 5.0E-05 1.0E-04 1.5E-04 2.0E-04 2.5E-04 3.0E-04 3.5E-04 00.020.040.060.080.10.120.140.160.180.2 1/Ce Ca (mg/L)1/(mass sorbed/sorbent) 1/( 1/Sm ax=7E-5, Sm ax=14286 KL= 1/(Slope*Sm ax)=0.05 S=14286*(0.05C)/(1+0.05C) 1/(mass so )] rbed/sorbent)[1/(mg/kg Figure A.58: Langmuir Isotherm Estimation-1% HC Ca Langmuir Isotherm-1% HC Ca0.0E+00 5.0E+03 1.0E+04 1.5E+04 2.0E+04 2.5E+04 3.0E+04 3.5E+04 4.0E+04 0.0050.00100.00150.00200.00250.00300.00350.00400.00450.00 Ce Ca (mg/L)Q(mg/k g Plotted Data Empirical Isotherm Q(mg/kg ) Figure A.59: Langmuir Isotherm-1% HC Ca 98

PAGE 116

Appendix A: (Continued) Linear Isotherm-3% HC Cay = 130.72x R2 = 0.9566 0.0E+00 1.0E+04 2.0E+04 3.0E+04 4.0E+04 5.0E+04 6.0E+04 0.0050.00100.00150.00200.00250.00300.00350.00400.00450.00 Ce Ca (mg/L)Q(mg/kg) ` Q(mg/kg) Figure A.60: Linear Isotherm-3% HC Ca 99

PAGE 117

Appendix A: (Continued) Freundlich Isotherm Estimation-3% HC Cay = 0.8019x + 2.3422 R2 = 0.6509 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 0.000.501.001.502.002.503.00 log(Ce Ca) [log(m g/L)]log( S) [log(mg / nF=0.8019 KF=102.3422=220 S=220C0.8019on-3% HC Ca Log(Q ]) )(log[mg/kg Figure A.61: Freundlich Isothe rm Estimati Freundlich Isotherm-3% HC Ca-1.0E+04 0.0E+00 1.0E+04 2.0E+04 3.0E+04 4.0E+04 5.0E+04 6.0E+04 0.0050.00100.00150.00200.00250.00300.00350.00400.00450.00Ce Ca (mg/L)Q(mg/ kg Plotted Data Empirical Isotherm Figure A.62: Freundlich Isotherm-3% HC Ca Q(mg/kg) 100

PAGE 118

Appendix A: (Continued) Langmuir Isotherm Estimation-3% HC Cay = 0.0036x + 0.0002 R2 = 0.5002 0.0E+00 1.0E-04 2. 5. 6.mass sorbed/sorbent) 1/ 0E-04 3.0E-04 4.0E-04 0E-04 0E-04 7.0E-04 00.020.040.060.080.10.120.14 1/Ce Ca (m g/L)1/( ( S=5000*(0.06C)/(1+0.06C) 1/Smax=0.0002, Sm ax=5000 KL= 1/(Slope*Smax)=0.06 1/(mass so )] rbed/sorbent)[1/(mg/kg Figure A.63: Langmuir Isotherm Estimation-3% HC Ca Langmuir Isotherm-3% HC Ca0.0E+00 1.0E+04 2.0E+04 3.0E+04 4.0E+04 5.0E+04 6.0E+04 0.0050.00100.00150.00200.00250.00300.00350.00400.00450.00 Ce Ca (mg/L)Q(mg/ g k Plotted Data Empirical Isotherm Q(mg/kg ) Figure A.64: Langmuir Isotherm-3% HC Ca 101

PAGE 119

Appendix A: (Continued) Linear Isotherm-1% MA Cay = 134.18x R2 = 0.9876 0.0E+00 1.0E+04 2.0E+04 3.0E+04 4.0E+04 5.0E+04 6.0E+04 0.0050.00100.00150.00200.00250.00300.00350.00400.00450.00 Ce Ca (mg/L)Q(mg/kg) ` Q(mg/kg) Figure A.65: Linear Isotherm-1% MA Ca 102

PAGE 120

Appendix A: (Continued) Freundlich Isotherm Estimation-1% MA Cay = 0.5873x + 3.0029 R2 = 0.8317 0.00 0.50 1.00 1.50 2.00 2. 3. 3. [log(mg 50 00 50 4.00 4.50 5.00 0.000.501.001.502.002.503.00 log(Ce Ca) [log(mg/L)]log(S) / nF=0.5873 KF=103.0029=1007 S=1007C0.5873on-1% MA Ca Log(Q)(log[mg/kg]) Figure A.66: Freundlich Isothe rm Estimati Freundlich Isotherm-1% MA Ca0.0E+00 1.0E+04 2.0E+04 3.0E+04 4.0E+04 5.0E+04 6.0E+04 0.0050.00100.00150.00200.00250.00300.00350.00400.00450.00Ce Ca (mg/L)Q(mg/ kg Plotted Data Empirical Isotherm Figure A.67: Freundlich Isotherm-1% MA Ca Q(mg/kg) 103

PAGE 121

Appendix A: (Continued) Langmuir Isotherm Estimation-1% MA Cay = 0.001x + 8E-05 R2 = 0.7889 0.0E+00 5.0E-05 1.0E-04 1.5E-04 2.0E-04 2.5E-04 3.0E-04 0 0.05 0.1 0.15 0.2 0.25 1/Ce Ca (m g/L)1/( mass sorbed/sorbent) 1/( S=12500*(0.08C)/(1+0.08C) 1/Sm ax=8E-5, Smax=12500 KL= 1/(Slope*Smax)=0.08 1/(mass so )] rbed/sorbent)[1/(mg/kg Figure A.68: Langmuir Isotherm Estimation-1% MA Ca Langmuir Isotherm-1% MA Ca0.0E+00 1.0E+04 2.0E+04 3. 0E+04 4.0E+04 5.0E+04 6.0E+04 0.0050.00100.00150.00200.00250.00300.00350.00400.00450.00Ce Ca (mg/L)Q(mg/ kg Plotted Data Empirical Isotherm Q(mg/kg) Figure A.69: Langmuir Isotherm-1% MA Ca 104

PAGE 122

Appendix A: (Continued) Linear Isotherm-3% MA Cay = 88.265x R2 = 0.882 0. 5. 1. 1. 2. 2. 3.Q(mg/kg) 0E+00 0E+03 0E+04 5E+04 0E+04 5E+04 0E+04 3.5E+04 4.0E+04 0.0050.00100.00150.00200.00250.00300.00350.00400.00450.00 Ce Ca (mg/L) Q(mg/kg) ` Figure A.70: Linear Isothe rm Estimation-3% MA Ca 105

PAGE 123

Appendix A: (Continued) Freundlich Isotherm Estimation-3% MA Cay = 0.5589x + 3.0226 R2 = 0.8935 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 0.000.501.001.502.002.503.00 log(Ce Ca) [log(m g/L)]log( S) [log(mg / nF=0.5589 KF=103.0226=1053 S=1053C0.5589 Ca Log(Q ]) )(log[mg/kg Figure A.71: Freundlich Isothe rm Estimation-3% MA Freundlich Isotherm-3% MA Ca-1.0E+04 -5.0E+03 0.0E+00 5.0E+03 1.0E+04 1.5E+04 2.0E+04 2.5E+04 3.0E+04 3.5E+04 4.0E+04 0.0050.00100.00150.00200.00250.00300.00350.00400.00450.00Ce Ca (mg/L)Q(mg/ kg Plotted Data Empirical Isotherm Figure A.72: Freundlich Isotherm-3% MA Ca Q(mg/kg) 106

PAGE 124

Appendix A: (Continued) Langmuir Isotherm Estimation-3% MA Ca y = 0.002x 8E-05 R2 = 0.379 -4.0E-04 -3.0E-04 -2.0E-04 -1 0. 1. 2.ass sorbed/sorbent) 1/( .0E-04 0E+00 0E-04 0E-04 3.0E-04 4.0E-04 00.020.040.060.080.10.120.140.160.180.2 1/Ce Ca (mg/L)1/(m m S=12500*(0.04C)/(1+0.04C) 1/Sm ax=8E-5, Smax=12500 KL= 1/(Slope*Smax)=0.04 1/(mass so nt)[1/(mg/kg)] rbed/sorbe Figure A.73: Langmuir Isotherm Estimation-3% MA Ca Langmuir Isotherm-3% MA Ca0.0E+00 5.0E+03 1.0E+04 1.5E+04 2.0E+04 2.5E+04 3.0E+04 3.5E+04 4.0E+04 0.0050.00100.00150.00200.00250.00300.00350.00400.00450.00Ce Ca (m g/L)Q(mg/ k g Plotted Data Empirical Isotherm Q(mg/kg) Figure A.74: Langmuir Isotherm-3% MA Ca 107

PAGE 125

Appendix A: (Continued) Figure A.75: Unexposed Bentonite x100 Figure A.76: Unexposed Bentonite x250 Figure A.77: Unexposed Bentonite x3500 108

PAGE 126

Appendix A: (Continued) Figure A.78: Unexposed Bentonite Spectrum Table A.7: Unexposed Bentonite Elemental Composition ELEMENTAL PEAK WEIGHT PERCENT ATOMIC PERCENT C K 34.38 45.31 O K 42.35 41.9 Na K 1.09 0.75 Mg K 0.86 0.56 Al K 4.77 2.8 Si K 13.92 7.84 S K 0.16 0.08 Ca K 0.55 0.22 Fe K 1.9 20.55 Total 100 100 109

PAGE 127

Appendix A: (Continued) Figure A.79: Unexposed Bentofix x100 Figure A.8exposed Bentofix x 0: Un 500 Figure A.81: Unexposed Bentofix x2000 110

PAGE 128

Appendix A: (Continued) Figure A.82: Unexposed Bentofix Spectrum Table A.8: Unexposed Bentofix Elemental Composition ELEMENTAL PEAK WEIGHT PERCENT ATOMIC PERCENT C K 15.52 23.82 O K 43.57 50.2 Na K 1.29 1.04 Mg K 1.69 1.28 Al K 11.29 7.71 Si K 21.23 13.93 S K 0.29 0.17 Ca K 1.25 0.57 Fe K 3.86 1.27 Total 100 100 111

PAGE 129

Appendix A: (Continued) Figure A.83: Unexposed Medium Anionic Polymer x100 Figure A.84: Unexposed Medium Anionic Polymer x600 Figure A.85: Unexposed Medium Anionic Polymer x3000 112

PAGE 130

Appendix A: (Continued) Figure A.86: Unexposed Medium Anionic Polymer Spectrum Table A.9: Unexposed Medium Ani onic Polymer Elemental Composition ELEMENTAL PEAK WEIGHT PERCENT ATOMIC PERCENT C K 60.52 67.84 N K 6.12 5.88 O K 27.34 23.01 Na K 4.38 2.57 Mg K 0.64 0.32 Si K 0.58 0.28 Fe K 0.43 0.1 Total 100 100 113

PAGE 131

Appendix A: (Continued) Figure A.87: Unexposed High Cationic Polymer x70 Figure A.88: Unexposed High Cationic Polymer x1000 Figure A.89: Unexposed High Cationic Polymer x10000 114

PAGE 132

Appendix A: (Continued) Figure A.90: Unexposed High Cationic Polymer Spectrum Table A.10: Unexposed High Cationic Polymer Elemental Composition ELEMENTAL PEAK WEIGHT PERCENT ATOMIC PERCENT C K 61.23 69.48 N K 11.25 10.95 O K 19.59 16.69 Pb M 0.5 0.03 Cl K 7.42 2.85 Total 100 100 115

PAGE 133

Appendix A: (Continued) Figure A.91: Sodium Exposed Bentonite x500 Figure A.92: Sodium Exposed Bentonite x10000 Figure A.93: Sodium Exposed Bentonite x25000 116

PAGE 134

Appendix A: (Continued) Figure A.94: Sodium Exposed Bentonite Spectrum Table A.11: Sodium Exposed Be ntonite Elemental Composition ELEMENTAL PEAK WEIGHT PERCENT ATOMIC PERCENT C K 22.56 31.51 O K 49.73 52.15 Na K 1.09 0.79 Mg K 0.82 0.57 Al K 6.3 3.92 Si K 17.44 10.42 Ca K 0.26 0.11 Fe K 1.79 0.54 Total 100 100 117

PAGE 135

Appendix A: (Continued) Figure A.95: Sodium Exposed Bentofix x500 Figure A.96: Sodium Exposed Bentofix x10000 Figure A.97: Sodium Exposed Bentofix x25000 118

PAGE 136

Appendix A: (Continued) Figure A.98: Sodium Exposed Bentofix Spectrum Table A.12: Sodium Exposed Bentofix Elemental Composition ELEMENTAL PEAK WEIGHT PERCENT ATOMIC PERCENT C K 3.15 5.05 O K 54.72 65.86 Na K 2.32 1.94 Mg K 1.85 1.46 Al K 10.74 7.66 Si K 25.36 17.38 Fe K 1.87 0.64 Total 100 100 119

PAGE 137

Appendix A: (Continued) Figure A.99: Sodium Exposed 3% Medium Anionic x500 Figure A.100: Sodium Exposed 3% Medium Anionic x10000 Figure A.101: Sodium Exposed 3% Medium Anionic x25000 120

PAGE 138

Appendix A: (Continued) Figure A.102: Sodium Exposed 3% Medium Anionic Spectrum Table A.13: Sodium Exposed 3% Me dium Anionic Elemental Composition ELEMENTAL PEAK WEIGHT PERCENT ATOMIC PERCENT C K 7.73 12.1 O K 51.79 60.89 Na K 1.92 1.57 Mg K 1.64 1.27 Al K 8.72 6.08 Si K 25.6 17 .15 Ca K 0.54 0.25 Fe K 2.05 0.69 Total 100 100 121

PAGE 139

Appendix A: (Continued) Figure A.103: Sodium Expos ed 3% High Cationic x500 Figure A.104: Sodium Expos ed 3% High Cationic x5000 Figure A.105: Sodium Expos ed 3% High Cationic x25000 122

PAGE 140

Appendix A: (Continued) Figure A.106: Sodium Exposed 3% High Cationic Spectrum Table A.14: Sodium Exposed 3% High Cationic Elemental Composition ELEMENTAL PEAK WEIGHT PERCENT ATOMIC PERCENT C K 8.83 13.8 O K 50.29 59.02 Na K 2.34 1.91 Mg K 1.63 1.26 Al K 8.79 6.11 Si K 24.9 16.65 Cl K 0.66 0.35 Ca K 0.28 0.13 Fe K 2.28 0.77 Total 100 100 123

PAGE 141

Appendix A: (Continued) Figure A.107: Calcium Exposed Bentonite x500 Figure A.108: Calcium Exposed Bentonite x10000 Figure A.109: Calcium Exposed Bentonite x25000 124

PAGE 142

Appendix A: (Continued) Figure A.110: Calcium Exposed Bentonite Spectrum Table A.15: Calcium Exposed Bentonite Elemental Composition ELEMENTAL PEAK WEIGHT PERCENT ATOMIC PERCENT C K 2.44 4.02 O K 52.52 65.05 Mg K 1.56 1.27 Al K 9.88 7.25 Si K 28.92 20.4 Cl K 0.62 0.35 Ca K 1.56 0.77 Fe K 2.51 0.89 Total 100 100 125

PAGE 143

Appendix A: (Continued) Figure A.111: Calcium Exposed Bentofix x500 Figure A.112: Calcium Exposed Bentofix x10000 Figure A.113: Calcium Exposed Bentofix x25000 126

PAGE 144

Appendix A: (Continued) Figure A.114: Calcium Exposed Bentofix Spectrum Table A.16: Calcium Exposed Bentofix Elemental Composition ELEMENTAL PEAK WEIGHT PERCENT ATOMIC PERCENT C K 43.02 53.21 O K 42.1 39.09 Mg K 0.62 0.38 Al K 4.13 2.27 Si K 8.66 4.58 Cl K 0.15 0.06 Ca K 0.54 0.2 Fe K 0.79 0.21 Total 100 100 127

PAGE 145

Appendix A: (Continued) Figure A.115: Calcium Exposed 3% Medium Anionic x500 Figure A.116: Calcium Exposed 3% Medium Anionic x1000 0 Figure A.117: Calcium Exposed 3% Medium Anionic x25000 128

PAGE 146

Appendix A: (Continued) Figure A.118: Calcium Exposed 3% Medium Anionic Spectrum Table A.17: Calcium Exposed 3% Me dium Anionic Elemental Composition ELEMENTAL PEAK WEIGHT PERCENT ATOMIC PERCENT C K 10.53 16.03 O K 53.3 60.91 Mg K 1.51 1.14 Al K 8.18 5.54 Si K 23.37 15.21 Ca K 1.12 0. 51 Fe K 1.99 0.65 Total 100 100 129

PAGE 147

Appendix A: (Continued) Figure A.119: Calcium Exposed 3% High Cationic x500 Figure A.120: Calcium Exposed 3% High Cationic x10000 Figure A.121: Calcium Exposed 3% High Cationic x25000 130

PAGE 148

Appendix A: (Continued) Figure A.122: Calcium Exposed 3% High Cationic Spectrum Table A.18: Calcium Exposed 3% High Cationic Elemental Composition ELEMENTAL PEAK WEIGHT PERCENT ATOMIC PERCENT C K 9.04 14.2 O K 50.25 59.22 Mg K 1.27 0.99 Al K 8.91 6.22 Si K 26.71 17.93 Ca K 1.2 0.57 Fe K 2.61 0.88 Total 100 100 131


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Nocon, Melody Schwartz.
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Inorganic sorption in polymer modified bentonite clays
h [electronic resource] /
by Melody Schwartz Nocon.
260
[Tampa, Fla] :
b University of South Florida,
2006.
3 520
ABSTRACT: In 1986, geosynthetic clay liners (GCLs) were invented and successfully used as a replacement for the soil layer in composite lining systems. In some applications an additive (polymer) is mixed with the bentonite to increase performance, especially in those that have low concentrations of sodium bentonite (EPA 2001).Studies showing significant increases in hydraulic conductivity values for bentonite in the presence of high salt concentrations are frequently documented and there is a risk of early breakthrough due to performance failure of the GCL clay component. (Ashmawy et al, 2002). It has also been stated that sodium, potassium, calcium, and magnesium have such a high affinity for the clay's surface other chemical species have little chance of attenuation (EPA 2001). For these reasons, researching sorption in the presence of major salt cations and polymers gains great importance.Distribution coefficients were extrapolated from Linear, Freundlich and Langmuir sorption isotherms for sodium and calcium cations modeled from data collected from batch tests of sodium bentonite and various manufactured and custom mixed polymer modified bentonites. Surface characterization before and after calcium or sodium solution exposure of all tested media was accomplished by use of scanning electron microscopy and energy dispersive x-ray analysis.
502
Thesis (M.A.)--University of South Florida, 2006.
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Includes bibliographical references.
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Text (Electronic thesis) in PDF format.
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System requirements: World Wide Web browser and PDF reader.
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Adviser: Alaa Ashmawy, Ph.D.
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Leachate.
GCL.
Isotherm.
Montmorillonite.
Salt.
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Dissertations, Academic
z USF
x Environmental Engineering
Masters.
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t USF Electronic Theses and Dissertations.
4 856
u http://digital.lib.usf.edu/?e14.1640