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24 0434134 X for Reference Only 24 0434134 X FOR REFERENCE ONLY ERRATA Page Location Correction 40 Line 14 compounds 81 Line 15 0.1 m mol. 84 Line 2 add "not" 103 Figure 3.10 omit "cation" 122 Line 27 surface tension 149 Figure 4.6 a = w/c 0. 35; b w/c 0.6 218 Figure 6.6 y-axis 10G Nm-2 270 Line 4 add "than" ORGANOPHILIC CLAYS IN STABILISATION AND. SOLIDIFICATION OF HAZARDOUS WASTES A thesis submitted to the University of London in partial fulfilment of the requirements for the degree of Doctor of Philosophy in the Faculty of Engineering and for the Diploma of Imperial College by D. M. Montgomery B.A.(Hons) October 1989 Centre for Toxic Waste Management, Department of Civil Engineering, Imperial College of Science, Technology and Medicine, University of London. 2 . ABSTRACT The major deficiencies in cement-based • stabilisation /solidification <S/S) processes are their Inability to treat inorganic wastes contaminated with organic material or organic wastes. In general, organic compounds are poorly retained in cement matrices and frequently have detrimental, poorly understood effects upon cement hydration. This study has shown how the cement-based S/S processes can be modified to allow the treatment of organic wastes by the use of organophlllc clays as pre-solldlflcatlon adsorbents. Organophilic clays, prepared by the treatment of Wyoming bentonite with a range of quaternary ammonium salts (QAS), were screened and the longer chain QAS-exchanged clays found to act as the best adsorbents for commonly occurring organic compounds. The exchanged clays solidified with cement performed well in physical tests giving high strength and low permeabilities. Leaching tests on the S/S mixes showed good retention of the phenolic compounds compared with the unstabilised cement/phenol mixes. Microstructural analysis showed that phenols inhibit the cement hydration reactions and form phenolates within the cement matrix. The presence of the clay in the cement mix reduced the detrimental effects of the organic compounds on cement hydration, although the clay itself altered the cement hydration reactions. Three Industrial wastes containing metals and organic contaminants were treated with the exchanged clay S/S mix. The samples produced were monolithic solids with good physical properties and good retention of the organic and metal compounds during leach testing. The stabilisation of contaminated soils by the exchanged clay showed large reductions in the release of phenols and polyaromatic hydrocarbons from laboratory dosed soils and soil contaminated with coal tar. I would like to dedicate this thesis to my parents in an attempt to express my gratitude for their support and encouragement throughout my whole university career. 4. ACKNOWLEDGEMENTS I would like to thank Professor R. Perry for giving me the opportunity to undertake this research and for the inspiration and encouragement along the way. I am especially indebted to Dr C. Sollars for his invaluable guidance and seemingly endless patience over the course of these studies. I would like to thank the Crystallography Department at Birkbeck College for allowing me to use their microstuctural equipment and I wish to particularly thank the staff there for their friendly and willing assistance. I also owe my thanks to my friends and collegues in the Public Health Section and at Imperial College for their cheerful support and encouragement over the years. Many thanks are also due to my friends outside college whose calm support and cheerful influence have helped me to keep going. 5. Contents Page Abstract 2 Acknowledgements 3 Contents 5 List of Tables 13 List of Figures 15 Notation 20 1. INTRODUCTION 21 1. 1 Legislation 22 1. 1. 1 Waste Terminology 22 1.1.2 Control of Pollution Act, 1974 25 1.1.3 EEC Policy on Waste Disposal 28 1.2 Waste Arisings 28 1.2. 1 United Kingdom 28 1.2.2 EEC Countries 29 1.2.3 Import of Waste to the UK 31 1.3 Disposal of Hazardous Wastes 31 1.3. 1 Disposal Routes in the UK 31 1.3.2 Disposal on Land 34 (a) Landfill 34 (b) Deep-well Disposal 35 1.3. 3 Incineration 35 1.3.4 Disposal at Sea 37 <a> Dumping at Sea 37 <b) Incineration at Sea 38 1.3.5 Pretreatment 39 (a) Physical Treatment 39 (b) Chemical Treatment 39 (c) Biological Treatment 40 1.4 Stabi1isation/Solidification 41 1.4.1 Sorption 42 1.4.2 Encapsulation 43 <a> Thermoplastic Processes 43 (b) Organic Polymers 44 (c) Vitrification 44 1.4.3 Inorganic Fixation 45 (a) Cement-Based Processes 45 <b> Pozzolanlc Processes 46 (c) Self Cementing 47 1.5 Cement- -Based Stabi1isation/Solidif ication 47 1.5. 1 Cement Hydration Chemistry 49 1.5.2 Interaction of Waste and Ordinary Portland 54 Cement (a) Research on Organic/Cement Interactions 54 (b) Organic Wastes 57 1.6 Clays 58 1.6. 1 Reactions of Clays with Organic Compounds 59 1.6.2 Structure of Montmori1 Ionite 60 1.6.3 Cation Exchanged Montmori1lonite 62 1.6.4 Adsorption of Organic Compounds by 66 Alkylammonlum Montmori1Ionite OBJECTIVES OF RESEARCH 70 ADSORPTION STUDIES 72 3.1 Introduction 72 7. 3.2 Materials and Methods 73 3.2.1 M aterials 73 3.2.2 Preparation of Quaternary Ammonium Salt 75 Exchanged Clays 3.2.3 Adsorption of Phenols from Water 78 3.2.4 Stability of Quaternary Ammonium Salts on 79 Montraori1 Ionite Clay 3.2.5 Effect of pH 80 3.2.6 Co-adsorption of Group IIB Metals with 81 3-Chlorophenol onto BODDMAM 3.2.7 Fourier Transform Infrared Spectroscopy 81 3.2.8 Thermal Analysis 82 3.2.9 Adsorption of Organics by ODTMAM 83 (a) Adsorption from Water 83 <b) Adsorption from Hexane 84 3.3 Results 85 3.3.1 Adsorption of Phenols from Water 85 3.3.2 Desorption with Time 91 3.3.3 Stability of Quaternary Ammonium Salts on 92 Montmori1 Ionite Clay 3.3.4 Effect of pH 95 3.3.5 Co-adsorption of Group IIB metals with 98 3-Chlorophenol onto BODDMAM 3.3.6 Fourier Transform Infrared Spectroscopy 100 3.3.7 Thermal Analysis 102 3.3.8 Adsorption of Organics Compounds by ODTMAM 111 (a) Adsorption from Water 111 (b) Adsorption from Hexane 114 3.4 Summary 117 4. STABILISATION/SOLIDIFICATION 119 4.1 Introduction 119 8. 4.2 Materials and Methods 119 4.2.1 Materials 119 4.2.2 Adsorption Studies 121 4.2.3 Sample Preparation 122 (a) Solidification of Samples for Physical 122 Testing (b) Solidification of Phenols from Aqueous 124 Solution (c) Long Term S tab ility of Exchanged Clays in 128 a Cement Matrix (d) Solidification of Aqueous Zinc and 129 3-Chlorophenol (e) Solidification of Liquid Organic Compounds 130 4.2.4 Physical Tests 132 (a) Setting Rate 132 (b) Unconfined Compressive Strength 132 (c) Water Adsorption 133 (d> Oxygen Permeability 133 (e) Mercury Intrusion Porosiraetry 136 4.2.5 Leach Tests 136 (a) Dynamic Leach Tests 136 (b) Equilibrium Leach Tests 137 (c) Equilibrium Leach Tests on Liquid Organic 137 Samples (d> Long Term Stability of Exchanged Clays in 138 a Cement Matrix 4.3 Results 139 4.3.1 Selection of Exchanged Clays 139 4.3.2 Physical Tests 142 (a) Unconfined Compressive Strength Tests 142 (b) Water Adsorption 148 (d) Oxygen Permeability 150 (e> Mercury Intrusion Porosimetry 150 4.3.3 Solidification of Phenols from Dilute Aqueous 153 Solution (a) Dynamic Leach Tests 153 9. <b) Equilibrium Leach Tests 157 (c) Long Term S tab ility of Exchanged Clay in 157 the Cement Matrix 4.3.4 Solidification of Zinc and 3-Chlorophenol from 160 Aqueous Solution <a) Dynamic Leach Tests 162 (b> Equilibrium Leach Tests 164 4.3.5 S olidification of Pure Organic Compounds 164 <a) Equilibrium Leach Tests 164 4.4 Summary 168 5. MICROSTRUCTURAL STUDIES 170 5.1 Introduction 170 5.2 Materials and Methods 171 5.2.1 Sample Preparation 171 5.2.2 Scanning Electron Microscopy 171 5.2.3 X-ray Diffraction Analysis 172 5.3 Results 172 5.3.1 Exchanging Quaternary Ammonium Cations onto 172 Wyoming Bentonite 5.3.2 Effect of Organic Compounds on Cement Hydration 174 5.3.3 Effect of Cement on Exchanged Clay 183 5.3.4 Effect of Exchanged Clay on Cement Hydration 187 5.3.5 Solidification of 3-Chlorophenol and 198 Ch1oronaphtha1ene 5.4 Summary 198 6. SOLIDIFICATION OF INDUSTRIAL WASTES 202 6.1 Introduction 202 10. 6.2 M aterials and Methods 202 6.2.1 M aterials 202 (a) Wastes 202 (b) Solidification Materials 204 6.2.2 Adsorption Experiments 204 6.2.3 Mix Development 205 6.2.4 Stabi1isation/Solidlf icat ion 207 (a) Unconfined Compressive Strength Tests 210 <b> Leach Testing 210 6.3 Results 210 6.3.1 Adsorption of Experiments 210 6.3.2 Mix Development 216 6.3.3 Stabi1isation/Solidif1cation 219 6.3.4 Industrial Application 224 6.4 Summary 226 7. CONTAMINATED SOIL TREATMENT 227 7.1 Introduction 227 7.2 Materials and Methods 229 7.2.1 M aterials 229 (a) Soils 229 7.2.2 Characteristics of Soils 230 7.2.3 Analytical Procedure for Polyaromatic 230 Hydrocarbons (a) Clean Up 232 (b) Preparation of Standards 233 (c) HPLC Analysis 233 (d) Detection 236 <e) Identification and Quantification 237 (f) Quality Control of the Analytical Method 238 7.2.4 Batch Tests 239 (a) Extraction of PAH from Aqueous Solution 239 11. 7.2.5 Column Tests 240 7.2.6 Solidification of Phenol Dosed Soils 241 (a) Strength Tests 242 (b) Leach Tests 243 7.3 Results 243 7.3.1 Phenol Dosed Soils 243 (a) Batch Tests 244 (b) Column Tests 246 7.3.2 Cement-Based Stabi 1 isat.ion/Solidification 246 (a) Unconfined Compressive Strength Tests 246 (b) Dynamic Leach Tests 249 (c) Equilibrium Leach Tests 249 7.3.3 Gasworks Soil 252 (a) Evaluation of Analytical Method for PAH 252 (b) Soil Analysis 252 (c) Batch Tests 255 (d) Column Tests 255 7.4 Summary 258 8.
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