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Impacts of Quicklime Application on Chlorinated Ethylenes in Soil

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Impacts of Quicklime Application on Chlorinated Ethylenes in Soil
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2008

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Chemicals ( jstor )
Chlorides ( jstor )
Chlorine ( jstor )
Dosage ( jstor )
Moisture content ( jstor )
Soil temperature regimes ( jstor )
Soil water ( jstor )
Soils ( jstor )
Vaporizing ( jstor )
Water temperature ( jstor )

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University of Florida
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IMPACTS OF QUICKLIME APPLICATION ON CHLORINATED ETHYLENES IN SOIL By JAE HAC KO A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2007 1

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2007 Jae Hac Ko 2

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To my parents and my loving wife. 3

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ACKNOWLEDGMENTS I would like to express my sincerest gratitude and appreciation to the chairman of my committee, Dr. Timothy G. Townsend, for his guidance, support and advice throughout my graduate study at University of Florida. I would also like to thank the other members of my committee, Dr. Angela Lindner, Dr. Joseph J. Delfino, and Dr. Roy D. Rhue for their participation and guidance. I thank Dr. W. Harris for his support at field and soil analysis for this research and Dr. Jaehyun Cho for sharing his knowledge. I wish to thank the Florida Department of Transportation (FDOT) for funding the research. And I thank Mr. Curtis Barnes and Mr. Terry Zinn for their support and help on the field work at Fairbanks site. I would like to thank Dr. Wayne Losano, Dr. Kimberly Cochran, Dr. Hwidong Kim, Dr. Dubey Brajesh Kumar, and Steven Musson for helping and reviewing this dissertation. I thank Dr. Qiyong Xu, Aaron Jordan and the follow graduate students in the solid and hazardous waste group for their assistance and cooperation in this work. I would like to thank Lakmini Geethika Wadanambi, Fernando Parraferro and Morgan W. Donovan for their assistance in laboratory experiments. I would like to thank particularly my parents and my family. Finally, the greatest thanks go to my wife, Yoonjung Kim, for her endless support, encouragement, and love. 4

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TABLE OF CONTENTS page ACKNOWLEDGMENTS ...............................................................................................................4 LIST OF TABLES ...........................................................................................................................9 LIST OF FIGURES .......................................................................................................................10 ABSTRACT ...................................................................................................................................13 CHAPTER 1 INTRODUCTION..................................................................................................................17 1.1 Background and Problem Statement............................................................................17 1.2 Research Objectives.....................................................................................................21 1.3 Research Approach......................................................................................................22 1.4 Outline of Dissertation.................................................................................................25 2 DESTRUCTION OF CHLORINATED ETHYLENES DURING HYDRATION OF CALCIUM OXIDE................................................................................................................27 2.1 Introduction..................................................................................................................27 2.2 Literature Review.........................................................................................................29 2.2.1 Destruction of Chlorinated Ethylenes with CaO and Alkali Hydroxide............29 2.2.2 Decomposition of Dichloroacetylene in the Presence of Oxygen.....................31 2.3 Methods and Materials.................................................................................................32 2.3.1 Reagents.............................................................................................................32 2.3.2 Materials............................................................................................................32 2.3.3 CaO Addition and Collection of Byproducts.....................................................33 2.3.4 Analytical Methods............................................................................................35 2.4 Results and Discussion................................................................................................36 2.4.1 Destruction of PCE and Byproduct(s) Resulting by CaO-treatment.................36 2.4.1.1 Percent recovery of CaO-treated PCE.......................................................36 2.4.1.2 Organic byproduct(s) in CaO-treated PCE................................................36 2.4.1.3 Formation of chloride in CaO-treated PCE...............................................37 2.4.1.4 Mass balance with organic and inorganic byproducts of PCE..................37 2.4.2 TCE Destruction and Byproducts Resulting from CaO Treatment...................38 2.4.2.1 Percent recoveries in CaO-treated TCE....................................................38 2.4.2.2 Organic byproduct(s) in CaO-treated TCE...............................................38 2.4.2.3 Formation of chloride in CaO-treated TCE...............................................40 2.4.2.4 Mass balance with organic and inorganic byproduct of TCE...................41 2.4.3 Destruction of cis-DCE and Byproducts Resulting by CaO-treatment.............41 2.4.3.1 Percent recoveries in CaO-treated cis-DCE..............................................41 2.4.3.2 Organic byproduct(s) in CaO-treated cis-DCE.........................................42 2.4.3.3 Formation of chloride of cis-DCE by the hydration of CaO.....................43 5

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2.4.3.4 Mass balance with organic and inorganic byproduct of cis-DCE.............44 2.5 Summary and Conclusions..........................................................................................44 3 IMPACTS OF TEMPERATURE AND TIME ON THE REACTION OF CALCIUM HYDROXIDE WITH TRICHLOROETHYLENE................................................................65 3.1 Introduction..................................................................................................................65 3.2 Literature Review.........................................................................................................67 3.2.1 Impact of Temperature on a Chemical Reaction...............................................67 3.2.2 Conversion of Ca(OH) 2 to CaCl 2 (or CaOHCl) by the Reaction of Ca(OH) 2 with HCl............................................................................................................68 3.2.3 Impacts of Temperature on the Reaction of Ca(OH) 2 with HCl and Ultimate Conversion of Ca(OH) 2 to CaCl 2 /CaOHCl........................................69 3.3 Methods and Materials.................................................................................................70 3.3.1 Reagents.............................................................................................................70 3.3.2 Reactions of TCE with Calcium Hydroxide at Different Temperatures............70 3.3.3 Calculation of Ca(OH) 2 Conversion to CaCl 2 /CaOHCl....................................71 3.3.4 Initial TCE Concentration in Gas Phase............................................................71 3.3.5 Analytical Method.............................................................................................72 3.4 Results and Discussion................................................................................................72 3.4.1 Amount of TCE Recovered after Ca(OH) 2 Treatment at Different Temperatures.....................................................................................................72 3.4.2 Formation of Chloride of Ca(OH) 2 -treated TCE...............................................73 3.4.3 Conversion of TCE to Organic Byproducts.......................................................74 3.4.4 Variation of the Mole Ratio of Cl Extracted to DCA.......................................74 3.4.5 Mass Balance of Treated TCE in the Contact with Ca(OH) 2 at Different Temperatures.....................................................................................................75 3.4.6 Impacts of Reaction Temperatures and Times on the transformation of TCE...................................................................................................................76 3.5 Summary and Conclusions..........................................................................................77 4 TRANSFORMATION OF CHLORINATED ETHYLENES IN SOIL BY THE ADDITION OF CALCIUM OXIDE......................................................................................86 4.1 Introduction..................................................................................................................86 4.2 Methods and Materials.................................................................................................89 4.2.1 Soils....................................................................................................................89 4.2.2 Reagents.............................................................................................................89 4.2.3 Temperature Measurement in CaO-added Soils................................................90 4.2.4 Synthesizing Contaminated Soils and CaO Addition........................................90 4.2.5 Analytical Method.............................................................................................91 4.3 Results and Discussion................................................................................................91 4.3.1 Temperature Dynamics during the Hydration of CaO.......................................91 4.3.2 Dechlorination of Chlorinated Ethylenes in the CaO-added Soils....................93 4.3.3 Dechlorination of cis-DCE and TCE and the Maximum Temperatures Achieved in the CaO-added soils......................................................................94 4.3.3 Implication and Limitations...............................................................................96 6

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4.4 Summary and Conclusions..........................................................................................97 5 THE REMOVAL OF TRICHLOROETHYLENE FROM SOIL USING THE HYDRATION OF CALCIUM OXIDE................................................................................106 5.1 Introduction................................................................................................................106 5.2 Influential Parameters Potentially Caused by CaO treatment....................................108 5.2.1 Temperature.....................................................................................................108 5.2.2 Water content...................................................................................................109 5.3 Methods and Materials...............................................................................................109 5.3.1 Reagents...........................................................................................................109 5.3.2 Soils..................................................................................................................109 5.3.3 Synthesis a TCE-contaminated Soils and CaO Addition.................................110 5.3.4 Estimation of Initial TCE in Headspace, Water Content, Percent Recovery, and Cumulative TCE Removal.......................................................................111 5.3.4.1 Initial TCE in headspace.........................................................................111 5.3.4.2 Estimating water content in CaO-treated materials.................................112 5.3.4.3 Percent Recovery and cumulative TCE removal....................................112 5.3.5 Chemical Analysis...........................................................................................113 5.4 Results and Discussion..............................................................................................113 5.4.1 Temperature Dynamics....................................................................................113 5.4.2 TCE Removal from Three Soils with Different CaO Doses............................114 5.4.3 TCE Volatilization by CaO Addition..............................................................115 5.4.4 Formation of Dichloroacetylene from TCE-contaminated Soil during CaO Treatment........................................................................................................117 5.4.5 Implications and Limitations...........................................................................118 5.5 Summary and Conclusions........................................................................................120 6 THE LEACHABILITY OF TRICHLOROETHYLENE FROM SIMULATED SOILS OF CALCIUM OXIDE-TREATMENT...............................................................................132 6.1 Introduction................................................................................................................132 6.2 Methods and Materials...............................................................................................134 6.2.1 Soils..................................................................................................................134 6.2.2 Reagents...........................................................................................................135 6.2.3 Synthesis of Simulated Post-CaO-treated Soils (SPS) and TCE-contaminated Soils (TS)..................................................................................135 6.2.4 Synthetic Precipitation Leaching Procedure (SPLP).......................................136 6.2.5 Total Concentrations of TCE in TSs and SPSs................................................136 6.2.6 Analytical Method...........................................................................................137 6.2.7 The Ratio of TCE Concentrations of a SPS to a TS........................................137 6.3 Results and Discussion..............................................................................................138 6.3.1 Observed TCE Concentration of in TSs and SPSs..........................................138 6.3.2 Observed TCE Leaching from TSs and SPSs by the SPLP Test.....................139 6.3.3 Implications and Limitations...........................................................................140 6.4 Summary and Conclusions........................................................................................141 7

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7 SUMMARY AND CONCLUSIONS...................................................................................149 7.1 Summary....................................................................................................................149 7.2 Conclusions................................................................................................................152 7.3 Integration, Application, and Limitations..................................................................155 APPENDIX A COMPONENTS OF TEST VESSEL DESIGNED..............................................................160 B FLORIDA CLEANUP TARGET LEVELS.........................................................................162 C OCCUPATIONAL EXPOSURE LIMITS...........................................................................163 D X-RAY DIFFRACTION PATTERNS OF SOILS USED IN CHAPTER 6........................164 LIST OF REFERENCES.............................................................................................................166 BIOGRAPHICAL SKETCH.......................................................................................................170 8

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LIST OF TABLES Table page 2-1 Summary of experimental conditions conducted for this study.........................................47 3-1 Chloroacetylene (CA) and PCE at the end of the treatment at 20 o C, 60 o C, 80 o C, and 100 o C..........................................................................................................................79 3-2 Chloroacetylene (CA) in treated samples at 20 o C, 60 o C, 80 o C, and 100 o C...................79 3-3 PCE in treated samples at 20 o C, 60 o C, 80 o C, and 100 o C...............................................79 4-1 Calcium oxide, water, and soil (20 g dry weight) used for this experiment......................99 4-2 Maximum temperatures measured in CaO-treated soils with different CaO/H 2 O ratios...................................................................................................................................99 5-1 Physical and chemical properties of soils used in this study...........................................123 5-2 Experimental parameters used for synthesizing contaminated soil and for CaOtreatment with a test vessel..............................................................................................123 5-3 Concentration of TCE calculated in the treated material with a 0 %, a 5 %, a 10 %, and a 20 % CaO dose.......................................................................................................124 5-4 The removal efficiencies of TCE in the soils treated with a 0 %, a 5 %, a 10 %, and a 20 % CaO dose.................................................................................................................124 6-1 Physical and chemical properties of test soils..................................................................143 6-2 Major minerals found in sand, silt, and clay fraction of the soils used............................143 6-3 Parameters used to synthesize simulated post-CaO-treated soils and TCE-contaminated soils............................................................................................................143 6-4 Concentrations of TCE in TSs and SPSs with 1-day and 7-day treatment (mg/kg)........144 6-5 TCE concentrations in the SPLP extracts of TSs and SPSs with 1-day and 7-day treatment (g/L)...............................................................................................................144 6-6 Percents of TCE leached to the SPLP extracts of TSs and SPSs from TCE in the TSs and the SPSs treated for 1 day and 7 days (unit: %)........................................................144 B-1 Florida Soil Cleanup Target Levels (SCTLs)..................................................................162 B-2 Florida Groundwater and Surface Water Cleanup Target Levels (GSWCT)..................162 C-1 Occupational Exposure Limits.........................................................................................163 9

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LIST OF FIGURES Figure page 2-1 Tentative scheme for the decomposition of DCA in the presence of oxygen (Reichert et al., 1980)........................................................................................................................48 2-2 Test vessel before (a) and after (b) CaO addition to chlorinated ethylene-water solution...............................................................................................................................49 2-3 Collection of byproducts after CaO treatment...................................................................49 2-4 Percent recoveries of PCE under different experimental conditions.................................50 2-5 TCE in the CaO-treated PCE under different experimental conditions.............................50 2-6 Chloride extracted in the CaO-treated PCE under different experimental conditions.......51 2-7 Mass balance of CaO-treated PCE under different experimental conditions....................52 2-8 Percent recoveries of TCE under different experimental conditions.................................53 2-9 Electron-impact mass spectra of byproducts by CaO-treated TCE. A) DCA, B) PCE, C) hexachlorobutadiene, and D) CA..................................................................................54 2-10 DCA in the CaO-treated TCE under different experimental conditions............................56 2-11 PCE in the CaO-treated TCE under different experimental conditions.............................56 2-12 Chloride extracted in the CaO-treated TCE under different experimental conditions......57 2-13 Mass balance of CaO treated TCE under different experimental conditions....................58 2-14 Percent recoveries of cis-DCE under different experimental conditions...........................59 2-15 Electron-impact mass spectra of byproducts by CaO treatedcis-DCE. A) CA, B) trans-DCE, C) TCE, and D) VC........................................................................................60 2-16 CA in the CaO-treated cis-DCE under different experimental conditions........................62 2-17 trans-DCE in the CaO-treated cis-DCE under different experimental conditions............62 2-18 TCE in the CaO-treated cis-DCE under different experimental conditions......................63 2-19 Chloride extracted in the CaO-treated cis-DCE under different experimental conditions...........................................................................................................................63 2-20 Mass balance of CaO-treated cis-DCE under different experimental conditions..............64 10

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3-1 Schematic presentation of the structure of the product layers...........................................80 3-2 TCE recovered after Ca(OH) 2 treatment with different temperatures...............................80 3-3 Chloride extracted after Ca(OH) 2 treatment at different temperatures..............................81 3-4 DCA after Ca(OH) 2 treatment at different temperatures...................................................81 3-5 Mole ratios of Cl to DCA by the Ca(OH) 2 treatment with different temperatures...........82 3-6. Mass balance of chorine using moles of chlorine in the byproducts after the degradation of TCE contacting Ca(OH) 2 at different temperatures...................................83 3-7 TCE, Cl , and DCA in the degradation of TCE contacting Ca(OH) 2 at different temperatures and times......................................................................................................84 3-8 Mole ratios of Cl to DCA with different temperatures and times.....................................85 4-1 Vapor pressures of cis-DCE, TCE, and PCE at different temperatures...........................100 4-2 Particle size distribution curves of coarse sand and loamy sand used.............................100 4-3 Change of temperature in soils treated with the different mole ratios of CaO to H 2 O. A) and B) are 5 % coarse sand and loamy sand. C) and D) are 10 % coarse sand and loamy sand................................................................................................................101 4-4 Levels of chloride in CaO-added soils with the different CaO/H 2 O ratios. A) 5 % coarse sand, B) 5 % loamy sand, C) 10 % coarse sand, and D) 10 % loamy sand..................................................................................................................................103 4-5 Ratio of Cl to Ca and the maximum temperatures achieved with different CaO/H 2 O ratios. A) cis-DCE-contaminated soils and B) TCE-contaminated soils.........................105 5-1 The particle size distribution of used soils (AE, E, and B)..............................................125 5-2 The collection of volatilized products in the methanol traps after adding CaO to a synthesized TCE-contaminant soil..................................................................................126 5-3 Examples of the change in temperature of the test vessel during slaking with 50 g B soil and a 5 %, a 10 %, or a 20 % CaO dose....................................................................127 5-4 Mass of residual TCE in the materials treated with a 0 %, a 5 %, a 10 %, and a 20 % CaO dose..........................................................................................................................127 5-5 Cumulative TCE removals (%) in soils treated with a 0 %, a 5 %, a 10 %, and a 20 % CaO Dose. A) AE soil, B) E soil, and C) B soil..............................................................128 5-6 DCA and TCE removed during CaO treatment with a 20 % CaO dose in different soils: A) AE soil, B) E soil, and C) B soil.......................................................................130 11

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6-1 Schematic diagram of the experimental procedure..........................................................145 6-2 Ratios of TCE concentrations in simulated post-CaO-treated soils (SPSs) to those of TCE-contaminated soils (TSs) with FB, N, AE, and B soil in 1-day and 7-day treatment. A) 1-day and B) 7-day....................................................................................146 6-3 Ratios of TCE concentrations in the SPLP extracts of simulated post-CaO-treated soils (SPSs) to those of TCE-contaminated soils (TSs) with FB, N, AE, and B in 1-day and 7-day treatment. A) 1-day and B) 7-day.............................................................147 6-4 Simple regression analysis with TCE concentrations of TSs and SPSs and those of the SPLP extracts. Solid line is the linear fitting curve with the results of TSs. Dashed line is the results of SPSs....................................................................................148 A-1 Components of a test vessel. A) a glass reactor with two sampling ports, B) Teflon plunger (side view and front view), and C) a Teflon cap for a sampling port.................160 D-1 AE soil X-ray diffraction patterns....................................................................................164 D-2 B soil X-ray diffraction patterns......................................................................................164 D-3 N soil X-ray diffraction patterns......................................................................................165 D-4 FB soil X-ray diffraction patterns....................................................................................165 12

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Abstract of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy IMPACTS OF QUICKLIME APPLICATION ON CHLORINATED ETHYLENES IN SOIL By Jae Hac Ko May 2007 Chair: Timothy G. Townsend Major: Environmental Engineering Sciences Quicklime is frequently used to facilitate construction projects by amending the physical properties of soil, such as water content and plasticity. A reaction process known as slaking occurs when calcium oxide is hydrated and heat is produced. Quicklime also has been used for soil cleanup. This research was motivated by observations of contaminant removal from quicklime-applied soils, particularly chlorinated solvents. Three feasible mechanisms for treatment of chlorinated ethylenes by adding CaO were studied: (1) degradation of the chemicals, (2) volatilization of the chemicals, and (3) immobilization of the contaminants in the soil-Ca(OH) 2 matrix. The fate of chlorinated ethylenes (tetrachloroethylene (PCE), trichloroethylene (TCE), and cis-dichloroethylene (cis-DCE)) was examined when CaO reacted with a chlorinated ethylene-water mixture in test vessels designed to minimize volatile loss. Results of the experiments indicated that chlorinated ethylenes did react to some degree with Ca(OH) 2 produced during the hydration of CaO to form organic byproducts. Evidence of dechlorination of chlorinated ethylenes was provided by concentrations of chloride in methanol extracts. The primary organic byproducts of the decomposition of TCE and cis-DCE were dichloroacetylene (DCA) and chloroacetylene (CA). Various secondary products formed likely because DCA and CA were 13

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unstable in the presence of air. The formation of DCA and CA from CaO-treated TCE and cis-DCE was hindered by the presence of excess water when the CaO/H 2 O ratio of 1:2 was used. The maximum decomposition of chloroethylenes was observed when the CaO/H 2 O ratio was 1:1 and air was present. This experiment proves that destruction of chlorinated ethylenes can occur to some extent when CaO reacts with a chlorinated ethylene-water mixture. The maximum destruction under the tested experiment conditions was estimated to be 0.3 % of PCE, 37.3 % of TCE, and 63.2 % of cis-DCE. The production of organic and inorganic byproducts when TCE was exposed to Ca(OH) 2 was investigated at different temperatures and times. The formation of organic byproducts and chloride increased with increasing temperature. However, the formation of organic byproducts did not vary with extended time. Dechlorination of TCE also was hindered as Ca(OH) 2 was converted to chlorine compound(s). These results showed that the destruction of TCE was enhanced by increasing temperature, but that the reaction might be hindered by a byproduct formed on Ca(OH) 2 . Minimizing volatilization, the dechlorination of chlorinated ethylenes in soil was determined with different mole ratios of CaO to H 2 O (0.5, 1.0, and 1.5) when CaO was added to the soils. Dechlorination of chlorinated ethylenes (cis-DCE, TCE, and PCE) was estimated by measuring extractable chloride concentrations. Dechlorination of the chlorinated ethylenes increased when the CaO/H 2 O ratio increased. The degree of dechlorination varied among the different chlorinated ethylenes (cis-DCE < TCE < PCE). The use of excess water when the CaO/H 2 O ratio was 1:2 reduced dechlorination of the chlorinated ethylenes, perhaps, because water prevented chloroethylene vapor from contacting Ca(OH) 2 . When the chloride concentration was compared with the maximum temperatures observed with different CaO/H 2 O 14

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ratios, increasing the temperature by increasing the CaO dose enhanced the dechlorination of chlorinated ethylenes. Volatilization and formation of byproducts were examined when TCE-contaminated soils were treated by 0 %, 5 %, 10 %, and 20 % CaO doses. Increasing the amount of CaO in the soils enhanced the volatilization of TCE from the soils. The results revealed that generating more heat with higher CaO doses overcame the obstacles retarding the TCE volatilization such as high organic content and clay content. However, the treatment with 20 % CaO dose led to the formation of an organic byproduct (DCA). To reduce the formation of byproducts and to increase TCE volatilization, the optimum doses of those tested were 5 % and 10 % CaO in sand with 0.55 % organic content (OC), 5 % CaO in sand with 0.13 % OC, and 10 % CaO in loamy sand with19.2 % clay. To assess the immobilization of TCE in a post-CaO treatment condition, simulated post-CaO-treated soils were synthesized by mixing a soil with Ca(OH) 2 and adding TCE-dissolved water. Sandy clay loam (FB) with 22.9 % clay and 0.05 % OC, loamy sand (N) with 10.5 % clay and 0.05 % OC, sand (AE) with 1.2 % clay and 0.55 % OC, and sandy loam (B) with 19.2 % clay and 0.06 % OC were used for the experiments. Non-treated TCE-contaminated soils (without Ca(OH) 2 ) were also prepared to compare with the simulated post-CaO-treated materials. The synthesized soils were treated for 1 day and 7 days at 20 o C, and the synthetic precipitation leaching procedure (SPLP) test was conducted on the soils. The total TCE concentrations in the simulated materials and the TCE concentrations in the SPLP extracts of the simulated materials were compared with those of non-treated TCE-contaminated soils. TCE reduction in the simulated post-CaO-treated materials was greater than in the non-treated soil in three of four soils used. The levels of TCE in the simulated post-CaO treated soils ranged from 17 % to 60 % 15

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of those in the non-treated TCE contaminated soils (FB, N and AE), but the levels of TCE in non-treated TCE-contaminated B soil ranged from 3 % to 67 % of those in the simulated post-CaO-treated B soil. The concentrations of TCE in the SPLP extracts were proportional to the total TCE concentrations added to the tested materials, but no evidence of enhanced immobilization was observed. The impact of adding CaO on chlorinated ethylenes in soil was studied with regard to degradation, volatilization, and immobilization. Degradation of chlorinated ethylenes (e.g., PCE, TCE, and cis-DCE) in water and wet soil with the hydration of CaO was demonstrated by the formation of organic byproducts and chloride in the extract. It is thought that destruction of TCE and cis-DCE may become a concern because of the formation of toxic organic byproducts. However, adjusting the initial water content in soil may be a way to control to the formation of byproducts. It was found that TCE volatilization from soil by the exothermic reaction of CaO was the primary mechanism of TCE removal and might be an alternative remediation option for excavated soil. However, an air emission control system may be necessary if the emission rate is higher than the regulation (2.5 kg per day for single compound and 6.2 kg per day for total compounds). To apply quicklime on field conditions with various VOCs, it is important to decide the optimum amount of CaO dose and water content to maximize volatile removal and minimize the formation of toxic chemicals. 16

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CHAPTER 1 INTRODUCTION 1.1 Background and Problem Statement Quicklime is frequently used to facilitate construction projects by amending the physical properties of soil, such as water content and plasticity. Quicklime usually contains 90-95 % calcium oxide (Boyton, 1980). A reaction process known as slaking occurs when calcium oxide is hydrated. The process consumes water and generates heat. The hydration of CaO occurs as: heatOHCaOHCaO22)( [1-1] The heat liberated by hydration of quicklime ranges from 880 to 1,140 kJ/kg depending on the CaO content of the quicklime (Boyton, 1980). Applying quicklime improves physical properties of fine-grained soils by adjusting the water content and flocculating soil particles (NLA, 2004). Quicklime may also be added as part of soil cleanup operations to create a more favorable physical soil condition. Lime and/or fly ash are often applied to oilor PCB-contaminated soils to reduce the physical migration of the contaminants by reducing the amount of water (Soundararajan, 1991). Quicklime has also been added to contaminated soil after excavation to improve its handling properties (FDOT, 2002). In addition to creating physical soil conditions that are more conducive to remediation, the quicklime can promote remediation through other mechanisms. Using quicklime to treat contaminated soils was suggested as an easier and more feasible way to treat PCBs in soil after an unanticipated observation of PCB-removal from quicklime-added soil (Soundararajan, 1991). Soundararajan achieved his laboratory results by mixing quicklime with a soil slurry with PCBs and heating the mixture for 72 hours, resulting in significant removal of PCBs from the examined soil. This investigation was limited, and the reaction mechanism remained unclear (Soundararajan, 1991). The expected remediation was proved wrong by later research by the 17

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U.S. Environment Protection Agency (U.S. EPA, 1991) and Sedlak et al. (1991). The USEPA (1991) and Sedlak et al. (1991), who reproduced Soundararajan’s experiment, concluded that, rather than being destroyed, PCBs were volatilized by adding quicklime and heating the mixture. At a site in Fairbanks, Florida, U.S.A, quicklime was added to excavated soils to increase the workability of soil containing a large fraction of clay (FDOT, 2002). After mixing, they found that several volatile organic pollutants were removed to levels below that required for cleanup (FDOT, 2002). The major contaminants at the Fairbanks site were highly volatile compounds, including trichloroethylene (TCE), 1,1,1-trichloroethane, 1,1-dichloroethlyene, and benzene. Air surveillance was conducted to measure air emission and employee exposure using personal air samplers on workers and four air sampling stations on the perimeter. Air sampling data from the site did not suggest volatilization to be a major pathway of the pollutant removal (FDOT, 2002). However, no complete mass balance of the chemicals before and after mixing was performed. Changes in soil chemistry by adding quicklime can also affect the behavior of contaminants in the soil. For example, the solubility of heavy metals can be altered because of the pH change resulting from quicklime addition (Dermatas and Meng, 2003; Marion and et al., 1997). In contrast to its effect on heavy metals, the impact of quicklime application on organic pollutants in the soil environment is relatively unknown. Three ways in which quicklime addition may affect the remediation of soil contaminated with organic chemicals are (1) degradation of the chemicals, (2) volatilization of the chemicals by increased temperature, or (3) immobilization of the contaminants in the soil-Ca(OH) 2 matrix (Sedlak et al., 1991). Regarding destruction of chlorinated organic contaminants in soil, most contaminants, such as chlorinated ethylenes and polychlorobiphenyls (PCBs), are stable in the soil environment. The hydration of CaO rarely leads to elevated temperatures sufficient for the 18

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thermally induced disruption of bonds. No decomposition of trichloroethylene (TCE) is reported at 300 o C, but partial decomposition of TCE does occur at 650 o C. Tetrachloroethylene (PCE) is very stable below 650 o C (Koper and Klabunde, 1997). Destruction of some chlorinated organic compounds by dechlorination in the presence of CaO has been reported under different reaction conditions. Kopper and Klabunde (1997) observed destruction of chlorinated hydrocarbons on calcium oxide particles in elevated temperatures (350 o C 500 o C). Hall et al. (1996) addressed the mechanochemical destruction of dichlorodiphenyltrichloroethane (DDT) with calcium oxide using a ball mill. The activation energy of the reaction between CaO and DDT was achieved by mechanically mixing in a ball mill. Calcium hydroxide (Ca(OH) 2 ) should also be considered as a possible reactant with organic contaminants since CaO quickly reacts with water to produce Ca(OH) 2 . The reactions between calcium hydroxide and chlorinated organic chemicals have been rarely reported. However, alkali metal hydroxides (NaOH or KOH) have been used in an alternative chemical dechlorination process with polyethylene glycol (PEG) reagents (Tiernan et al., 1989). Gu and Siegrist (1997) examined the dechlorination of TCE with NaOH under different temperatures (40~100 o C) and found dichloroacetate, Na-glycolate, monochloroacetate, and NaCl as intermediate or final products. Volatilization is another possible mechanism of contaminant removal through quicklime treatment because of the increase in temperature caused by the hydration of CaO. Volatilization of organic chemicals is widely used as a separation technique in soil remediation processes. Volatilization of a chemical from soil into the atmosphere relies on the physical and chemical properties of the contaminants, the sorptive characteristics of the soil, contaminant 19

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concentrations, water content, the air flow rate, diffusion, and temperature (Guenzi and Beard, 1974). When soil is mixed with quicklime, the temperature of the soil increases temporarily while water content decreases. The elevated temperature can increase the gas-phase concentration of an organic contaminant because the vapor pressure of the contaminant increases when the temperature increases. The decrease in water content may create more pathways for the gas-phase contaminant to reach the atmosphere. However, if the organic compounds are non-polar, the drying of the soil may increase the adsorption capacity of the compounds to the soil particles and result in reducing the escape of the compounds to the atmosphere (Ong and Lion, 1991). In addition to destruction or volatilization of an organic contaminant, quicklime addition may also reduce the mobility of the contaminant in soil. This could be important for remediation activities most concerned with the leachability pathway. Whereas some heavy metals are immobilized by physical as well as chemical changes when quicklime is added to soil (Dermatas and Meng, 2003), volatile organic compounds (VOCs) are difficult to immobilize through stabilization or solidification. VOCs are volatilized quickly when exposed to ambient air. When water is present in soil, water can displace VOCs that are sorbed on soil particles (Marco et al., 1996). Marco et al. (1996) studied VOC immobilization in soil using organic binders (shredded tire particles, rice hull ash) and encapsulating agents (ordinary Portland cement and sodium silicate). They found that the most effective combination of an organic binder and an encapsulating agent was shredded tire particles and sodium silicate. If an organic chemical is not removed completely by quicklime application, the rest of the chemical likely remains in the treated materials. After the added quicklime is slaked completely in soil, the residual chemical may undergo additional reduction, including immobilization and 20

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destruction, by the adjusted soil environment. Predicting the behavior of the chemical in the treated material is important to decide how finally to handle the treated material. 1.2 Research Objectives This research examines the impacts of CaO on the fate of chlorinated ethylenes including cis-dichloroethylene (cis-DCE), trichloroethylene (TCE), and perchloroethylene (PCE) in soil. Destruction of the chemicals, volatilization of TCE, and leachability of TCE in the CaO-treated soil were explored. The destruction of the chlorinated ethylenes in water and in soil by CaO-application was studied using batch experiments. Factors that affect the volatilization of TCE were explored by collecting volatilized products during the CaO treatment. Finally, the leachability of TCE in CaO-treated soil was evaluated using the synthetic precipitation leaching procedure (SPLP). To understand the true impacts of CaO addition on selected chlorinated ethylenes, five primary objectives were established in this research. The first objective was to determine whether destructive reaction(s) of chlorinated ethylenes occurred during hydration of CaO, using batch test vessels. Since the formation of products depends upon the reaction mechanism, finding the decomposed products can help to estimate the reaction mechanism(s). If a reaction of a chlorinated ethylene with CaO or Ca(OH) 2 occurs, calcium chloride (CaCl 2 )/calcium hydroxichloride (CaOHCl) are the most suspected solid products of the destruction. This suggests that extractable chloride in the treated material may be used as an indicator to measure an extent of inorganic byproducts in the solid form. Understanding the mechanisms of the reactions of the contaminants with CaO/Ca(OH) 2 supplies fundamental information for using quicklime for treating contaminated soils. The second objective was to explore the impact of reaction temperatures in detail using TCE. The amount of heat generated by the hydration of CaO varies with the amounts of water and CaO added. The peak temperature observed varies if the amount of heat generated by the 21

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hydration of CaO and the amount of heat consumed by materials vary. The destructive reaction may be affected by temperatures by the hydration of CaO added. The third objective was to examine the degradation of chlorinated ethylenes in the soil environment. Temperature rises by CaO addition in water may be different from those in soil. The amount of available water for the hydration of CaO may vary with soil composition. Thus, the different amounts of the available water may also affect the temperature peak and the reaction(s). Based on the previous studies, the degradation of chlorinated ethylenes resulted in the formation of a chlorine compound (s); the levels of water-extractable chloride in the treated materials were used as an index of the reaction. The fourth objective was to measure TCE removal by volatilization and to measure byproducts formed by CaO treatment. Temperatures elevated by the hydration of CaO can increase the gas-phase concentration of TCE through an increase of vapor pressure. Increasing the gas-phase concentration of TCE will likely result in removal of TCE by volatilization. However, the TCE removal and the decomposition of TCE may vary with different CaO doses in different soil compositions because the amount of heat generated depends on the amount of hydrated CaO and the heat is dissipated by adjacent materials. The fifth objective was to measure the TCE reduction and leachable TCE in CaO-treated soil. The soil-Ca(OH) 2 matrix may affect the leachability of TCE from the treated materials because of the modified soil environment by CaO addition. The duration of the treatment may affect the leachability as well. Determining the leachability of CaO-treated materials is an important consideration for the later use of the treated materials in terms of regulatory perspective. 1.3 Research Approach Five laboratory experiments were conducted to achieve the objectives described above. 22

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Objective 1: Determine occurrences of the decomposition of chloroethylenes (tetrachloroethylene (PCE), trichloroethylene (TCE), and cis-dichloroethylene (cis-DCE)) by measuring organic byproducts and extractable chloride in the CaO-treated materials; measure the amounts and the formation of byproducts by the CaO treatment in the presence and absence of air; compare the amounts of the decomposed chloroethylenes and byproducts of chlorinated ethylenes treated with the CaO/H 2 O ratio of 1:1 and 1:2; and calculate mass balances of CaO-treated chloroethylenes using the amount of chlorine in byproducts. Approach: A vessel was developed to add CaO to a mixed solution of water with a chlorinated ethylene (a contaminant) without a significant amount of contaminant loss. To determine the impact of the amount of water on the decomposition of a contaminant, 1:1 and 1:2 mole ratios of CaO to water were used simulating a scenario when CaO completely consumes water and when left-over water is present after the hydration of CaO. The impact of the presence and absence of air on the reaction was determined by comparing byproducts with and without purging air with helium through the vessel before the treatment. After the treatment, the byproducts were collected in methanol extract and methanol traps. Byproducts of chemicals were qualified and quantified. Objective 2: Measure the amount of organic byproducts and water-extractable chloride when TCE was exposed to Ca(OH) 2 at different temperature; measure organic byproducts and chloride at different times and temperatures. Approach: Using the same test vessel used for Objective 1, the treatment of TCE with Ca(OH) 2 was conducted with different temperatures in a dry oven. Temperatures used were 20 o C, 60 o C, 80 o C, and 100 o C. Time for the treatment was 12 hours and 24 hours at 20 o C and ranged from 0.5 hours to 5 hours at 60 o C, 80 o C, and 100 o C. The TCE and byproducts were 23

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collected as they were for Objective 1. The ratios of DCA to water-extractable chloride were compared at different temperatures and times. Objective 3: Measure temperature peaks in coarse sand and loamy sand by CaO treatment with different mole ratios of CaO to H 2 O, and measure the amount of water-extractable chloride in the treated soils to determine extent of dechlorination of chlorinated ethylenes. Approach: Minimizing volatilization, the CaO treatment of soils contaminated with chlorinated ethylenes was conducted by a method using VOA vials. The soils used were coarse sand and loamy sand. The mole ratios of CaO to water used were 0.5, 1.0, and 1.5. The temperature of a treated material was measured with a temperature probe inserted into the material during the treatment. The level of chloride in a treated material was determined by measuring chloride in water extract of the treated material. Objective 4: Measure the volatile removals of TCE when TCE-contaminated soils were treated with different amounts of CaO, and measure the amount of decomposed products along volatilizing TCE by CaO addition Approach: By continuously flushing the headspace of the test vessel with nitrogen gas during treatment of TCE-contaminated soil with CaO, TCE removed by volatilization was collected in methanol traps. Two sands and sandy loam that were collected from three soil master horizons with different depths were used to synthesize contaminated soils. The amounts of CaO used for the treatments were equivalent to 0 %, 5 %, 10 %, and 20 % of a dry soil (gravimetric basis). The TCE removed was collected by changing the methanol traps with scheduled times (5, 10, 15, 20, 25, 30, 40, 50, 60, 75, 95, 120, 150, and 180 minutes). The TCE remained in the treated materials was extracted by adding methanol into test vessels after CaO treatment. The TCE removed by volatilization with different CaO doses was compared. Byproducts collected in 24

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the methanol traps were measured as well. The temperature was monitored during treatment. The volatilization and destruction of TCE in three soils with various CaO doses were determined. Objective 5: Measure the change of the total TCE concentration in soils that simulated CaO treatment with mixing Ca(OH) 2 with the soils, measure TCE concentration in the leaching solutions of the SPLP tests with the treated soils, and compare the concentration in the SPLP solution to the total concentration. Approach: To simulate CaO-treated soils, four soils—sandy clay loam (FB) with 22.9 % clay and 0.05 % OC, loamy sand (N) with 10.5 % clay and 0.05 % OC, sand (AE) with 1.2 % clay and 0.55 % OC, and sandy loam (B) with 19.2 % clay and 0.06 % OC—were mixed with Ca(OH) 2 separately and with adjusted water content with TCE dissolved water. Non-treated soils without Ca(OH) 2 were prepared in the same way. The change in total TCE concentration in the treated and non-treated soils was measured by extracting with methanol after 1-day and 7-day treatments. A leachable concentration of TCE from the treated and non-treated soils was measured using the synthetic precipitation leaching procedure (SPLP) test. 1.4 Outline of Dissertation This dissertation is organized into seven chapters. Chapter 1 provides background information and problems regarding quicklime application on remediation sites, as well as the objectives and approaches of this research. Chapter 2 investigates the formation of byproducts of chlorinated ethylenes during hydration of CaO. Chapter 3 explores the impact of reaction temperatures on the formation of decomposed products of TCE. Chapter 4 describes the formation of water-extractable chloride in chlorinated ethylene-contaminated soil treated with different amounts of CaO. Chapter 5 explores the volatilization and decomposition of TCE during CaO treatment in different soils. Chapter 6 examines the leachability of TCE in simulated CaO-treated soils. Chapter 7 summarizes and presents conclusions. Appendix A though D 25

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contain additional information for Chapters 2 through 6. The references cited are included at the end of this dissertation. 26

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CHAPTER 2 DESTRUCTION OF CHLORINATED ETHYLENES DURING HYDRATION OF CALCIUM OXIDE 2.1 Introduction Calcium oxide (CaO) has often been used for altering of the physical properties of fine-grained soil to facilitate construction projects and cleanup (Soundararajan, 1991; FDOT, 2002; NLA, 2004). At a site in Fairbanks, Florida, U.S.A., quicklime was added to excavated soils that contained a high fraction of clay to help with the handling of contaminated materials during a cleanup (FDOT, 2002). After mixing, it was found that several volatile organic pollutants were removed to levels below that required for cleanup. The major contaminants at the Fairbanks site were highly volatile compounds, including trichloroethylene (TCE), 1,1,1-trichloroethane, 1,1-dichloroethlyene, and benzene that were disposed solvents generated by the Florida Department of Transportation (FDOT) Material Research Laboratory. Unanticipated observations of organic contaminant removal from soil by the application of quicklime raised questions about the possibility of the chemical destruction of contaminants with CaO and Ca(OH) 2 . FDOT officials believed that if such a process were to occur, it would occur in conjunction with volatilization of the volatile organic compounds (VOCs) by exothermic reactions during quicklime treatment. Destruction of chlorinated chemicals with CaO has been reported (Hall et al., 1996; Koper and Klabunde, 1997). Kopper and Klabunde observed the destruction of chlorinated hydrocarbons on calcium oxide particles at elevated temperatures (350 o C 500 o C), referred as to destructive adsorption. Hall et al. (1996), using a ball mill, addressed the mechanochemical destruction of DDT with calcium oxide. The activation energy for reactions between CaO and chlorinated hydrocarbons can be achieved by mechanical mixing in the ball mill. Calcium hydroxide (Ca(OH) 2 ) should also be considered as a possible reactant with organic contaminants since CaO quickly reacts with water to create Ca(OH) 2 . There is little 27

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literature on the reactions between calcium hydroxide and chlorinated ethylenes. However, alkali metal hydroxides have been used in an alternative chemical dechlorination process with polyethylene glycol (PEG) reagents (Tiernan et al., 1989). Reactions and byproducts should be verified when a treatment technology is applied. In many reactions, intermediate products may cause negative effects on human health or the environment even though the final products are safe. The degree of the reactions, the intermediate products, and other factors involved in the quicklime-organic chemical reaction are logical concerns if this treatment technique were to be applied to soils. The hydration of calcium oxide in the presence of chlorinated ethylenes may cause the decomposition of the chlorinated ethylenes and result in the formation of byproduct(s). The variety of byproducts may depend upon the reaction environment, for example, the presence of air (oxygen) and the amount of water for hydration. This study was devoted to describing the chemical reactions of chlorinated ethylenes during the hydration of calcium oxide. The fate of chloroethylenes (tetrachloroethylene (PCE), trichloroethylene (TCE), and cis-dichloroethylene (cis-DCE)) during the hydration of CaO was assessed by measuring organic byproducts and inorganic products in the treated material (using extractable chloride). The impact of water on the reaction was evaluated by conducting the experiment at two mole ratios of CaO/H 2 O: 1:1 and 1:2. The impact of the presence of air was evaluated by conducting experiments in the presence of air and in the absence of air. Finally, the mass balances of CaO-treated chloroethylenes were calculated using the amount of chlorine in byproducts. 28

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2.2 Literature Review 2.2.1 Destruction of Chlorinated Ethylenes with CaO and Alkali Hydroxide Potential destruction mechanisms have been reported between chlorinated organic chemicals and CaO. The reactions of chlorinated organic carbons with CaO or alkali metals include destructive adsorption, mechanochemical decomposition including a mechanochemical reaction by mechanical agitation (i.e., using a ball mill), and dechlorination by alkali metals. Recently, Koper et al. (1993) studied the use of CaO as an adsorbent and reactant in the destruction of some chlorinated hydrocarbons at elevated temperatures (300 – 500 o C). In their experiments, Koper et al. used a U-tube pulsed reactor to cause chlorinated hydrocarbon to react on the surface of a heated metal oxide. The results suggested that CaO favored destructive adsorption of some simple chlorinated hydrocarbons. Based on the thermodynamic heat of the reaction ( ), several exothermic reactions of chlorinated hydrocarbon destruction with metal oxides are hypothesized (Koper et al., 1993; Koper and Klabunde, 1997): orxnH 3CaO + 2CHCl 3 3CaCl 2 + 2CO + H 2 O = -719 kJ [2-1] orxnH Above 300 o C 3CaO + 2CHCl 3 3CaCl 2 + CO 2 + C+ H 2 O = -892 kJ [2-2] orxnH Initial CaO + C 2 HCl 3 CaOCl 2 + C 2 HCl [2-3] Overall 3CaO + 2C 2 HCl 3 3CaCl 2 + 2C (3C) + H 2 O + 2CO(CO 2 ) = -901 kJ (-1074) [2-4] orxnH 3CaO + C 2 Cl 4 2CaCl 2 + CaCO 3 + C = -842 kJ [2-5] orxnH The main products of the reactions between CaO and chlorinated hydrocarbons are CaCl 2 , H 2 O, and CO 2 (or CO) as noted in the chemical equations. Acetylene (C 2 H 2 ), chloroacetylene (C 2 HCl), and dichloroacetylene (C 2 Cl 2 ) were observed as intermediates during destructive 29

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adsorption of TCE at 450 o C by Koper and Klabunde (1997). The surface area of the metal oxide and the intrinsic reactivity are emphasized because the reactions are based on a surface-gas reaction (Koper et al., 1997). Hall et al. (1996) employed CaO to destroy chlorinated compounds by using a mechanochemical reaction. Activation energy was achieved in a mechanochemical reaction by mechanical agitation. Hall proved that mechanochemical decomposition of DDT with CaO was possible using a ball mill. In this study, DDT was completely decomposed within a 12-hour operation time without a detectable amount of VOC emissions. Loiselle at al. (1997) compared mechanochemical decomposition of chlorobenzenes over calcium hydride. The intermediates of a mechanochemical reaction might be harmful, however, even though detoxification is completed at the end of the reaction. Little research has been done on the mechanochemical treatment of VOCs. Calcium hydroxide (Ca(OH) 2 ) may be considered a possible reactant with organic contaminants since CaO quickly reacts with water to produce Ca(OH) 2 . Reactions between calcium hydroxide and organic chemicals have rarely been reported. However, the reaction between alkali hydroxides such as NaOH and KOH and chlorinated hydrocarbons has been addressed (Firth and Stuckey, 1945). The formation of dichloroacetylene (DCA) (the maximum production was achieved at 130 o C) by the reaction of alkali hydroxides to TCE (shown below) has been reported by Ott et al. (1931). HClClCHClCNaCl2232 [2-6] OHNaClNaOHHCl2 [2-7] NaOH was also used in an alternative chemical dechlorination process with polyethylene glycol (PEG) reagents (Tiernan et al., 1989). Gu and Siegrist (1997) examined the dechlorination 30

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of TCE with NaOH at different temperatures (40-100 o C) and found dichloroacetate, Na-glycolate, monochloroacetate, and NaCl as intermediate or final products. The formation of dichloroacetylene (DCA) has also been reported from TCE in contact with soda lime, a mixture of Ca(OH) 2 , NaOH, KOH, and water (Firth and Stuckey, 1945), not only from contact with pure alkali metals. Greim et al. (1984) also observed the formation of DCA from TCE in contact with building materials, such as concrete or tile filling material with an alkaline pH of 11 to 13. If chlorinated compounds are decomposed by CaO or Ca(OH), a final solid product may be CaCl 2 , a strongly hygroscopic chemical. Allal et al. (1998) addressed the instability of CaCl 2 in the presence of Ca(OH) 2 and its transformation to calcium hydroxichloride (Ca(OH)Cl). Bausach et al. (2004) proved that Ca(OH)Cl was also hygroscopic and that a stable product was formed by the reaction of Ca(OH) 2 and hydrogen chloride (HCl) in contact with the atmosphere. If calcium chloride or calcium hydroxichloride forms during the hydration of calcium oxide in the presence of chlorinated compounds, chloride can be reached to a water-extract out of from the solid product. For example, the aqueous solubility of CaCl 2 is 74.5g/100 mL (Lide, 1996). 2.2.2 Decomposition of Dichloroacetylene in the Presence of Oxygen DCA, a potential product of the reaction of CaO or Ca(OH) 2 with TCE, may form other products in ambient air since it is very unstable and spontaneously inflammable in the presence of air and water. Firth and Stuckey (1945) predicted that the decomposition of DCA in the presence of oxygen leads to the formation of phosgene and that in the presence of water DCA caused the formation of dichloracetylchloride and trichloracetyl chloride. Reichert et al. (1980) suggested that the toxicity of TCE might be explained by products of DCA decomposition. They detected decomposition products of DCA, such as phosgene, chloroform, carbon tetrachloride, tetrachloroethylene, trichloroacetyl chloride, and trichloroacryloyl, by allowing air to enter a 31

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glass container that held a mixture of DCA and nitrogen gas. They predicted three reaction pathways for the formation of the DCA decomposition products by using a radical mechanism, shown in Figure 2-1. Phosgene was the major product of oxidative decomposition of DCA in their research. Firth and Stuckey assumed that trichloroacetyl chloride and trichloroacryloyl chloride were products because of consecutive reactions of phosgene to other intermediate radicals. In spite of the instability of DCA in the presence of air and water, DCA was detected in the air samples since DCA can be stabilized by the presence of a high concentration of TCE (Firth and Stuckey, 1945; Anders, 2005). 2.3 Methods and Materials 2.3.1 Reagents Calcium oxide (Fisher Scientific, Certified Grade, 99 %) was used to treat water containing chlorinated ethylene compounds, such as cis-1,2-dichloroethylene (Acros Organics, 97 %), trichloroethylene (Alfa Aesar, 99.5 %), and tetrachloroethylene (Acros Organics, 99+ %). Vinylidene chloride (Acros Organics, 99.9 %) and trans-1,2-dichloroethylene (Acros Organics, 98 %) were used to confirm the retention time of formed byproducts in a chromatogram with a mass spectrometry and to prepare analytical standards used during analysis. Vinyl chloride (Ultra Scientific, 100 g/mL in methanol) was used as an external standard. Methanol (Fisher Scientific, GC grade) was used to collect and extract byproducts. 2.3.2 Materials A reaction test vessel, shown in Appendix A, consisted of a glass reactor with two sampling ports (Figure A-1), a Teflon plunger with a cavity (Figure A-2), and two thread-Teflon caps for the sampling ports (Figure A-3). The glass reactor was made of three threaded-glass connectors and one glass tube (assembled by Prism Research Glass, Inc., Research Triangle 32

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Park, NC, USA). One glass connector (Connector # 25) was located at the top of a glass tube, and two connectors (Connectors # 7) were located at both sides of the glass tube. The Teflon plunger was designed with a cavity to carry CaO into the reaction vessel. The plunger was screw-threaded to fit and seal at Connector # 25 with four o-ring seals to ensure an air-tight boundary. An o-ring was located before and after the CaO delivery cavity (Simriz, perfluoroelastomer, Aerospace Semiconductor Chemical Process Business Unit, CA USA) and two o-rings (Viton, fluoroelastomer, DuPont Dow Elastomers L.L.C., DE USA) surrounded the screw-thread head. The total length of the Teflon plunger (fabricated by Scientific Machine, Middlesex, NJ, USA) was 145 mm with a cavity of 50 mm (length) x 16 mm (width) x 15 mm (depth). Each sampling port was covered by a double-threaded, open-top cap. The cap was designed to connect a side sampling port and a Teflon stopcock valve (Cole-Parmer, IL, USA). A Teflon-faced septum was located between the port and the cap to prevent leaks during treatment. 2.3.3 CaO Addition and Collection of Byproducts A measured amount of CaO was loaded into the Teflon plunger cavity, and the plunger was inserted into the top of the reactor until the first three plunger o-rings were within the glass connector #25 (Figure 2-2). The two Simriz o-rings held the Teflon plunger in the glass tube tightly and isolated the CaO from outside air moisture and the headspace of the vessel. To minimize secondary reactions of unstable chemicals in the presence of air, helium was added gently over the CaO without blowing it out of the holder before CaO was isolated by the three o-rings. Helium was also added to the vessel before and after water was added to the vessel through an uncapped sampling port. A contaminant was spiked into the water and the vessel was sealed quickly with a cap and septum. The volumes of spiked cis-DCE, TCE, and PCE were 100 L, which are equivalent to 1.3, 1.0, and 1.0 mmol respectively. These values were selected arbitrarily. CaO was then added to chlorinated ethylene-water solution by screwing the Teflon 33

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plunger down and emptying CaO from the cavity into the main body of the vessel. When the cavity was open to the headspace, CaO was dropped into the contaminated water by tapping (Figure 2-2) and mixed by shaking the vessel. Two mole ratios of CaO to water, 1:1 and 1:2, were used to examine the impact of the presence of extra water on the destruction. The added amount of CaO was 166 mmol (equal to 9.3 g CaO) and that of water was 167 mmol (referred as to CaO/H 2 O ratio of 1:1) or 333 mmol (referred to as CaO/H 2 O ratio of 1:2). After the CaO addition, the vessels were kept in an insulated box for 24 hours. Identical experiments were conducted without adding helium to create conditions where air is present. Table 2-1 summarizes the experimental conditions with the contaminants. To collect byproducts in the CaO-treated samples and in the headspace of the test vessel, methanol was added to the headspace of the vessel. Methanol was added by pressurizing a methanol reservoir with nitrogen gas (30 mL/min), forcing the methanol to move into the vessel through stainless metal tubing (Figure 2-3). As methanol filled the test vessel, displaced gas from the headspace was bubbled through two VOA vials connected via stainless steel tubes through septa. The VOA vials contained 30 mL of methanol each. After most of the test vessel was filled with methanol, the vessel was shaken to extract contaminants from the treated material. The methanol extract in the vessel and the methanol in the traps were analyzed to measure contaminant and byproducts. The methanol extract of the vessels was analyzed for chloride as well. The percent recoveries of the contaminants were calculated using Eq. 2-8. 100(%)chemicalspikedaofamounttotal thetrapsmethanolandextractthein chemicalcollectedofsumthe RecoveryPercent [2-8] 34

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For mass balance calculation, moles of chlorine of a target chloroethylene and its byproducts were used. The percent of chlorine moles of a product () to total moles of chlorine was calculated using the percent of moles of chlorine in a product, i, to moles of chlorine in a chlorinated ethylene that was spiked into a test vessel initially as shown in Eq. 2-9. The difference between moles of chlorine in the chlorinated ethylene spiked and the sum of the moles in products is termed as unknown that may include chemicals not collected or missed. The percent unknown was calculated using Eq. 2-10. (%),iPCln 100(%),,,inClPClPClnnnii [2-9] iPCln, = moles of chlorine on product i iiippPClNnn, and inininClNnn , ipn = moles of product i ipN = number of chlorine atoms on a molecule of product i inCln, = moles of chlorine on chloroethylene initially spiked into a test vessel inn = moles of product i inN = number of chlorine atoms on a molecule of the chloroethylene 100(%),1,,,inClniPClinClunknownClnnnni [2-10] niPClin1, = the sum of chlorine moles in all products. 2.3.4 Analytical Methods Collected chemicals in the extracts and traps were analyzed by a gas chromatograph equipped with a mass spectrometry (GC/MS, Finnigan Trace 2000) and a gas chromatograph using a flame ionization detector (GC/FID, Hewlett Packard 5890 Series II). The chloride in the methanol extracts was analyzed with an ion chromatograph (DIONEX LC20 and CD20) that was 35

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operated with 1.20 mL/min of effluent flow rate through an Allsep Anion 7u column (Alltech, Deerfield, Illinois, USA). Dichloroacetylene (DCA) and chloroacetylene (CA) were not quantified directly since commercial standards were not available. Greim et al. (1984) used 1,2-dichloroethylene with an analogous structure and estimated that the error might not exceed more than 50 %. For this research, the quantification of DCA and CA was conducted using 1.2-dichloroethylene and vinyl chloride. 2.4 Results and Discussion 2.4.1 Destruction of PCE and Byproduct(s) Resulting by CaO-treatment 2.4.1.1 Percent recovery of CaO-treated PCE The percent recovery of PCE in CaO-treated PCE with different CaO/H 2 O ratios in the absence and presence of air are shown in Figure 2-4. The average percent of PCE recovered with a CaO/H 2 O ratio of 1:1 in the absence of air and in the presence of air was 91.2 ( 4.5) % and 92.3 ( 1.2) %, respectively. The percent recoveries were reduced to 73.0 ( 13.5) % and 75.6 ( 1.9) % with a CaO/H 2 O ratio of 1:2 with the absence and presence of air respectively. The low percent recoveries with a CaO/H 2 O ratio of 1:2 might be caused by the low efficiency of methanol extraction. Since the residual water in the CaO-treated samples was physically clumped calcium hydroxide particles and caused the treated materials to stick to the wall of the vessel, the methanol added was, perhaps, not able to access PCE trapped in the Ca(OH) 2 clumps. 2.4.1.2 Organic byproduct(s) in CaO-treated PCE The only organic byproduct detected in CaO-treated PCE was TCE as a result of GC/MS analysis. As Figure 2-5 shows, the amounts of TCE produced were very low compared with the spiked PCE (1 mmol). The average total amounts of TCE founded ranged between 0.0027 (.0028) mmol and 0.0030 (.0023) mmol with large standard deviations in the samples in the 36

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absence of air. In the presence of air, the amount of TCE formed was 0.0002 (.0002) mmol and 0.0007 (.0002) mmol with a CaO/H 2 O ratio of 1:1 and 1:2, respectively. The results indicate that the formation of TCE was higher with the lack of air. If 1 mole of CaO-treated PCE produces 1 mole of TCE, the recovered levels of equivalent TCE to PCE ranged from 0.02 % to 0.3 % of the amount of spiked PCE. The formation of TCE from CaO-treated PCE showed that dechlorination of PCE occurred during the hydration of CaO. 2.4.1.3 Formation of chloride in CaO-treated PCE The amounts of chloride extracted from CaO-treated PCE under different conditions are shown in Figure 2-6. The levels of extracted chloride with a CaO/H 2 O ratio of 1:1 were slightly higher than those with a CaO/H 2 O ratio of 1:2. Comparing the levels of chloride detected to the levels of the formed TCE, the chloride concentrations were not proportional to the level of the TCE in the same experimental conditions. The produced TCE might decompose during the hydrating CaO, but no byproduct of decomposed TCE was detected. 2.4.1.4 Mass balance with organic and inorganic byproducts of PCE Mass balance with the byproducts of CaO-treated PCE is shown in Figure 2-7. On analyzing calculation results, it was found that the contribution of decomposed products on the mass balance was negligible (less than 0.3 % in total). The results of mass balance calculations with the byproducts of PCE in the presence of air were similar to those in the absence of air. However, the contribution of unknown in the mass balance increased with the CaO/H 2 O ratio of 1:2. The percent unknown ranged from 7.8 % to 8.6 % with a CaO/H 2 O mole ratio of 1:1 and which increased to a range of 24.3 % to 26.8 % with a CaO/H 2 O ratio of 1:2. As discussed in the previous section, the low percent recovery of PCE with a CaO/H 2 O ratio of 1:2 was not because of the degradation of PCE treated but because the low efficiency methanol extraction for PCE at the experimental condition. 37

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2.4.2 TCE Destruction and Byproducts Resulting from CaO Treatment 2.4.2.1 Percent recoveries in CaO-treated TCE Percent recoveries of TCE in CaO-treated TCE did not vary except with a CaO/H 2 O ratio of 1:1 in the presence of air as shown in Figure 2-8. The average percent recoveries of TCE were 63.8 (.0.9) % and 61.9 (.9) % when TCE was treated with a CaO/H 2 O ratio of 1:2 in the absence of air and in the presence of air, respectively. The average percent recoveries with a CaO/H 2 O ratio of 1:1 in the absence of air was 60.1 (.8) %, but the recovery of TCE was decreased extensively to 27.1 (.0) % when TCE was treated with a CaO/H 2 O ratio of 1:1in the presence of air. Comparing the percent recoveries of TCE to those of PCE, the difference of percent recoveries ranged from 9.2 % to 13.7 % with the CaO/H 2 O mole ratio of 1:2 but from 31.1 % to 65.2 % with the CaO/H 2 O mole ratio of 1:1. The significant difference between the percent recoveries TCE and PCE under the same experimental condition indicated that a large amount of TCE decomposition occurred, particularly in the case of the CaO/H 2 O ratio of 1:1. 2.4.2.2 Organic byproduct(s) in CaO-treated TCE The organic byproducts identified in CaO-treated TCE varied under experimental conditions and included DCA, PCE, hexachlorobutadiene, and chloroacetylene (CA), as shown in Figure 2-9. The spectra of a byproduct were compared to the spectra of a chemical in the NIST library (NIST Mass Spectral Search Program for NIST/EPA/NIH Mass Spectral Library, Version 2.0c). The primary byproduct of the CaO-treated TCE was DCA (Figure 2-9). No evidence of the formation of cis-DCE, trans-DCE, or 1,1-DCE from treated TCE samples was observed. The formation of DCA indicated that HCl was eliminated from TCE contacting Ca(OH) 2 (Eq. 2-11). 38

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HClClCHClCOHCa22)(322 [2-11] The quantities of DCA produced varied under different reaction conditions (Figure 2-10). The estimated level of DCA with a CaO/H 2 O mole ratio of 1:1 in the absence of air was four times higher than in the presence of air. This is because the DCA in the absence of air was more stable than in the presence of air. As Figure 2-11 shows, PCE was found only in the samples treated with a CaO/H 2 O ratio of 1:1, but the amount of PCE formed in the presence of air was nine times higher than in the absence of air. The quantities of PCE with and without air were 0.00790.0009 mmol and 0.0009.0003 mmol, respectively. Reichert et al. (1984) explained the formation of PCE by the degradation of DCA in the presence of air. The considerable amount of PCE formed with a CaO/H 2 O ratio of 1:1 in the presence of air supported the degradation of DCA formed in CaO-treated TCE. However, the formation of PCE was observed with CaO/H 2 O in absence of air as well. This result suggested that PCE could be formed in the absence of air. With the presence of excess water with the CaO/H 2 O ratio of 1:2, the formation of PCE was not observed. These results were likely because leftover water hindered the degradation of DCA or the formation of DCA. Hexachlorobutadiene (0.0024 0.001 mmol) and CA (0.0004 0.0002 mmol) were found only in the samples treated with the CaO/H 2 O ratio of 1:1 in the presence of air. Hexachlorobutadiene, previously reported by Rechaert et al. (1980), was detected only in TCE treated with a CaO/H 2 O ratio of 1:1 in the presence of air. However, phosgene, a major decomposition product of DCA by oxidation, was not detected. Phosgene may react with methanol to form methyl chloroformate (Pasquato et al., 2000). Methyl chloroformate was not found in the samples treated or in the methanol traps. In addition, trichloroacetyl chloride and 39

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trichloroacryloyl chloride, which are related to reactions between phosgene and other oxidative products (Figure 2-1), were not found. This result may be because treating TCE with the given experimental conditions in the presence of air reduces the formation of phosgene or decomposes the phosgene formed. With a CaO/H 2 O ratio of 1:2 (in the presence of excess water), the formation of DCA was significantly reduced compared to that with the CaO/H 2 O ratio of 1:1. The presence of excess water during hydration of CaO is thought to have prevented TCE vapors from contacting Ca(OH) 2 by competitive adsorption on the surface of Ca(OH) 2 . The amount of DCA formed in the absence of air was similar to that in the presence of air with the CaO/H 2 O ratio of 1:2, suggesting that the impact of air on the DCA decomposition might not be significant when the CaO/H 2 O ratio is 1:2. As a result of the decrease in DCA formation, the formation of secondary organic byproducts was reduced. Formation of PCE, CA, and hexachlorobutadiene was not observed with a CaO/H 2 O ratio of 1:2. 2.4.2.3 Formation of chloride in CaO-treated TCE The extracted chloride concentrations in CaO-treated TCE are shown in Figure 2-12. Extractable chloride was found in all samples treated, but significant chloride concentrations were only present with a CaO/H 2 O ratio of 1:1. Chloride concentration with a CaO/H 2 O ratio of 1:1 in the presence of air was three times as high as that in the absence of air and 10 times as high as those with a CaO/H 2 O ratio of 1:2. The high chloride concentration explained the lowest percent recovery of TCE with a CaO/H 2 O ratio of 1:1 in the presence of air in spite of the lowest quantity of DCA formed. Assuming that 1 mole of TCE produced 1 mole of HCl (Eq. 2-11) and that HCl produced are completely consumed by Ca(OH) 2 , the moles of extracted chloride formed when TCE was treated with the CaO/H 2 O ratio of 1:1 in the presence of air exceeded the equivalent moles of chloride to the TCE reduced. The difference between average moles of TCE 40

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recovered and moles of spiked TCE was 0.7 mmol when TCE was treated with a mole ratio 1:1 in the presence of air, but the average amount of extracted chloride was 1.1 mmol. This result showed that chlorine compounds were formed not only by HCl (Eq. 2-12) produced by the dehydrochlorination of TCE, but also by other unknown sources of chlorine. OHCaClOHCaHCl2222)(2 [2-12] 2.4.2.4 Mass balance with organic and inorganic byproduct of TCE Mass balance with the amount of chlorine in organic and inorganic byproducts of CaO-treated TCE is shown in Figure 2-13. With a CaO/H 2 O ratio of 1:1, the chlorine in recovered TCE and products was 82.7 % of the chlorine in spiked TCE in the absence of air and 64.4 % in the presence of air. The percent of chlorine in the organic byproducts was 22.7 % of the chlorine in the spiked TCE in the absence of air and was 37.3 % in the presence of air. The percent of chlorine was 10.8 % in the absence of air and 32.8 % of TCE in the presence of air. With a CaO/H 2 O mole ratio of 1:2, the percent of chlorine in the recovered TCE and products was 66.8 % of the chlorine in the spiked TCE in the presence of air and 69.4 % in the absence of air. The percent of TCE decomposed using the amount of chlorine in decomposed products was around 5 % of chlorine in the spiked TCE in the presence of excess water (a CaO/H 2 O ratio of 1:2). 2.4.3 Destruction of cis-DCE and Byproducts Resulting by CaO-treatment 2.4.3.1 Percent recoveries in CaO-treated cis-DCE Percent recoveries of cis-DCE after the CaO treatment under different reaction conditions are shown Figure 2-14. Percent recoveries of cis-DCE with the CaO/H 2 O ratio of 1:1 in the absence of air and in the presence of air were 50.0 ( 3.7) % and 20.1 ( 4.3) % of the spiked cis-DCE, respectively. Percent recoveries of cis-DCE were 73.6 (.3) % and 74.2 ( 3.6) % in the CaO/H 2 O ratio of 1:2 with the absence of air and in the presence of air, respectively. The average 41

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percent recoveries of cis-DCE with different experimental condition showed trends similar to those of TCE. These results show that the decomposition of cis-DCE during the hydration of CaO was enhanced with a CaO/H 2 O ratio of 1:1 in with the presence of air. 2.4.3.2 Organic byproduct(s) in CaO-treated cis-DCE The results under different reaction conditions showed not only different percent recoveries of cis-DCE but also different organic byproducts and different quantities of the byproducts. Figure 2-15 compares the mass spectra of products. The organic byproducts of CaO-treated cis-DCE included chloroacetylene (CA), trans-DCE, TCE, and vinyl chloride (VC). VC (0.029.003 mmol) was detected only with a CaO/H 2 O ratio of 1:1 in the presence of air. The primary organic byproduct of CaO-treated cis-DCE was CA. The formation of CA is additional evidence of elimination of HCl during CaO-treatment (Eq. 2-13). The estimated quantities of CA in the CaO-treated cis-DCE with different conditions are shown in Figure 2-16. With a CaO/H 2 O ratio of 1:1, the estimated quantity of CA in the absence of air was almost three and half times as high as that in the presence of air. HClHClCClHCOHCa2)(2222 [2-13] The instability of CA in the presence of air causes the amounts of CA formed in the presence of air to differ from those formed in the absence of air as discussed with DCA in CaO-treated TCE. The second most abundant organic byproduct found under all conditions (Figure 2-17) was trans-DCE. With a CaO/H 2 O ratio of 1:1, the amount of trans-DCE formed in presence of air was 33 times as high as that in the absence of air. The levels of CA and cis-DCE in the presence of air were lower than those in the lack of air when cis-DCE was treated with a CaO/H 2 O ratio of 1:1. These results suggested that the formation of trans-DCE might be associated with the additional decomposition of cis-DCE by the reaction of cis-DCE to CA in the presence of air. 42

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TCE also was found in all treated samples and the level of TCE did not vary with the reaction conditions (Figure 2-18). The quantities of TCE were not very low compared to the other products. The results indicated that the formation of TCE by CaO-treated cis-DCE might not be affected by the presence/absence of air. Enough evidence to prove the reaction pathway of TCE formation was not found. With a CaO/H 2 O ratio of 1:2, the formation of CA dramatically decreased in the CaO-treated cis-DCA. Also, the formation of trans-DCE was reduced. The amount of formed organic byproducts with a CaO/H 2 O ratio of 1:2 in the absence of air did not vary from that in the presence of air. The formation of organic byproducts was reduced significantly by the presence of excess water, perhaps for the same reason as with CaO-treated TCE. 2.4.3.3 Formation of chloride of cis-DCE by the hydration of CaO The extracted chloride concentrations in CaO-treated cis-DCE are shown in Figure 2-18. Extractable chloride concentration in CaO-treated cis-DCE showed the same trends as that in the CaO-treated TCE. The quantities of the chloride formed with various conditions were close to those in CaO-treated TCE. With regard to the transformation of cis-DCE to inorganic products, the fate of cis-DCE by the hydration of CaO was similar to that of TCE. Comparing moles of chloride and reduced cis-DCE with a CaO/H 2 O ratio of 1:1 in the presence of air, moles of chloride surpassed the moles of reduced cis-DCE. This result showed that the chlorine compounds was formed not only by HCl (Eq. 2-13) produced by the dehydrochlorination of cis-DCE, but also by other unknown sources of chlorine. With the presence of extra water (a CaO/H 2 O ratio of 1:2), the transformation of cis-DCE was significantly reduced in CaO-treated cis-DCE. 43

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2.4.3.4 Mass balance with organic and inorganic byproduct of cis-DCE Mass balances of the CaO-treated cis-DCE using moles of chlorine in products are shown in Figure 2-20. With a CaO/H 2 O ratio of 1:1 in the presence of air, the percent of chlorine in byproduct was 120.8 % of the chlorine of the spiked cis-DCE. This result showed that the level of CA using VC as the analytical standard was overestimated. The percent of chlorine in cis-DCE and byproducts was 83.5 % of the chlorine in the spiked cis-DCE with a CaO/H 2 O ratio of 1:1 in the presence of air. The percent of chlorine in byproducts alone was estimated as 63.2 % of chlorine of the spiked cis-DCE with a CaO/H 2 O ratio of 1:1 in the presence of air. With a CaO/H 2 O ratio of 1:2, the total chlorine recovered was 79.9 % and 79.1 % of the total in the presence of air and the absence of air, respectively. The percent of chlorine in the byproducts with the presence of air and the absence of air was 5.7 % and 4.3 % of the chlorine of spiked cis-DCE, respectively. 2.5 Summary and Conclusions This study investigated the fate of PCE, TCE, and cis-DCE during the hydration of CaO. The results of this study showed that chlorinated ethylenes underwent partial destruction by CaO treatment. The number of products and quantities of the products varied with the reaction environments. A part of added PCE was destroyed during CaO-treatment but appeared fairly stable compared to other chlorinated ethylenes used. The decomposition of PCE by CaO treatment formed TCE, but there was a lack of evidence to prove the reaction pathway. The estimated decomposition of PCE by mass balance with chlorine did not exceed more than 0.3 % of initial PCE under the experimental conditions. The primary organic byproduct of the CaO-treated TCE was DCA. The other organic byproducts included PCE, hexachlorobutadiene, and chloroacetylene (CA). The maximum 44

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production of DCA was observed when TCE was treated with a CaO/H 2 O ratio of 1:1 in the absence of air. Hexachlorobutadiene and CA were only detected when TCE was treated with a CaO/H 2 O ratio of 1:1 in the presence of air. However, products of oxidative DCA were not detected in the presence of air. When TCE was treated with excess water for the hydration of CaO (a CaO/H 2 O ratio of 1:2), the formation of DCA was significantly reduced. Competitive adsorption of water and TCE vapors on the surface of Ca(OH) 2 might affect the formation of DCA. The reduction in formation of DCA perhaps reduced the formation of secondary organic byproducts as well. The formation of chloride was considerable when TCE was treated with the CaO/H 2 O ratio 1:1 in the presence of air. The formation of chloride was reduced in the presence of excess water. Chloride of the treated TCE was formed not only by HCl produced by the dehydrochlorination of TCE, but also by other unknown sources of chlorine. With a CaO/H 2 O ratio of 1:1, the percent of chlorine in the byproducts was 22.7 % of the chlorine in spiked TCE when treated with the absence of air but was 37.3 % when in the presence of air. In the presence of excess water, the chlorine of byproducts was around 5 % of the chlorine of initial TCE. Treatment with CaO partially decomposed cis-DCE. The organic byproducts observed were chloroacetylene (CA), trans-DCE, TCE, and vinyl chloride (VC). The primary organic byproduct was CA. The instability of CA in the presence of air resulted in reducing the amount of CA and in increasing the formation of secondary byproducts (trans-DCE, TCE, and VC) in the presence of air. With a CaO/H 2 O ratio of 1:2, the formation of CA was considerably reduced. When cis-DCE was treated with a CaO/H 2 O ratio of 1:2, the amount of organic byproducts formed in the 45

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absence of air did not vary from those in the presence of air. The lower formation of CA resulted in reducing secondary organic byproducts in the presence of excess water. The formation of chloride of cis-DCE by the CaO hydration was enhanced by a CaO/H 2 O ratio of 1:1 in the presence of air but was reduced by the presence of excess water. The maximum decomposition of cis-DCE was shown when cis-DCE was treated with a CaO/H 2 O ratio of 1:1 in the presence of air and the percent of chlorine in the byproducts was estimated as 63.2 % of chlorine in spiked cis-DCE. With a CaO/H 2 O ratio of 1:2, the percent of chlorine in the byproducts in the presence of air and in the lack of air was 5.7 % and 4.3 % of chlorine of initial cis-DCE, respectively. CaO application with chlorinated ethylenes leads to the formation of decomposition products that have negative effects on human health and the environment. Florida’s cleanup target levels and occupational exposure limits are shown in Appendices B and C. However, the species as well as the quantity of byproducts formed varies with the reaction environments. It is possible to reduce the formation of unwanted products by controlling a parameter such as the amount of water and CaO dose. 46

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Table 2-1. Summary of experimental conditions conducted for this study CaO (g) H 2 O (mL) Mole ratio of CaO/H 2 O Spiked chloroethylene (100 g) without air (Helium was added to a test vessel with 1200mL/min for 20 min) 9.3 3 1:1 PCE 9.3 3 1:1 TCE 9.3 3 1:1 cis-DCE 9.3 6 1:2 PCE 9.3 6 1:2 TCE 9.3 6 1:2 cis-DCE with air (Helium was not added) 9.3 3 1:1 PCE 9.3 3 1:1 TCE 9.3 3 1:1 cis-DCE 9.3 6 1:2 PCE 9.3 6 1:2 TCE 9.3 6 1:2 cis-DCE 47

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CCCl Cl CCCl Cl COCl Cl COCl Cl + Cl• + Cl• CCCl ClCl • CCCl ClCl • CCCl ClClCl CCCl ClClCl CCCl ClClCl OCl CCCl ClClCl OCl COCl• COCl• COCl• •CCl3 •CCl3 CCl4 CCl3C OCl CCl3C OCl H2O H2O CHCl3-Cl• -Cl• CC•Cl CC•Cl CCCl CC Cl CCCl CC Cl CCCl Cl CC ClCl ClCl CCCl Cl CC ClCl ClCldichloroacetylenephosgenecarbon tetrachlorideperchloroethylenetrichloroacryloyl chloridetrichloroacetyl chloridehexachlorobutadienechloroform CC•Cl + + O2 + Cl2 -Cl• CCCl Cl CCCl Cl COCl Cl COCl Cl + Cl• + Cl• CCCl ClCl • CCCl ClCl • CCCl ClClCl CCCl ClClCl CCCl ClClCl OCl CCCl ClClCl OCl COCl• COCl• COCl• •CCl3 •CCl3 CCl4 CCl3C OCl CCl3C OCl H2O H2O CHCl3-Cl• -Cl• CC•Cl CC•Cl CCCl CC Cl CCCl CC Cl CCCl Cl CC ClCl ClCl CCCl Cl CC ClCl ClCldichloroacetylenephosgenecarbon tetrachlorideperchloroethylenetrichloroacryloyl chloridetrichloroacetyl chloridehexachlorobutadienechloroform CC•Cl + CC•Cl + + O2 + O2 + Cl2 -Cl• Figure 2-1. Tentative scheme for the decomposition of DCA in the presence of oxygen (Reichert et al., 1980). 48

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chlorinated ethylene-water solutionTeflon insertCaOinner capouter cap 45o 45o headspace chlorinated ethylene-water solutionTeflon insertCaOinner capouter cap 45o 45o headspace CaO-treated material A B Figure 2-2. Test vessel before (a) and after (b) CaO addition to chlorinated ethylene-water solution. 45o N2flowvalve ventmethanol traps N2Gasregulator methanol reservoir methanol headspace products a treated sample 45o N2flowvalve ventmethanol traps N2Gasregulator methanol reservoir methanol headspace products a treated sample Figure 2-3. Collection of byproducts after CaO treatment 49

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He-1:1He-1:2Air-1:1Air-1:2 recovery (%) 020406080100 Figure 2-4. Percent recoveries of PCE under different experimental conditions. In the X-axis labels, “He” indicates the helium-purged condition and “Air” indicates a reaction condition without purging helium. :1” indicates when the ratio of CaO to H 2 O is 1:1 and :2” when it is 1:2. The error bars represent the standard deviation of three replicates. He-1:1He-1:2Air-1:1Air-1:2 TCE (mmol) 0.0000.0010.0020.0030.0040.0050.006 Figure 2-5. TCE in the CaO-treated PCE under different experimental conditions. In the X-axis labels, “He” indicates the helium purged condition and “Air” indicates a reaction condition without purging helium. :1” indicates when the ratio of CaO to H 2 O is 1:1 and :2” when it is 1:2. The error bars represent the standard deviation of three replicates. 50

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He-1:1He-1:2Air-1:1Air-1:2 Cl(mmol) 0.00000.00010.00020.00030.00040.00050.00060.0007 Figure 2-6. Chloride extracted in the CaO-treated PCE under different experimental conditions. In the X-axis labels, “He” indicates the helium purged condition, and “Air” indicates a reaction condition without purging helium. :1” indicates when the ratio of CaO to H 2 O is 1:1 and :2” when it is 1:2. The error bars represent the standard deviation of three replicates. 51

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He-1:1He-1:2Air-1:1Air-1:2 % 020406080100 PCE unknown Figure 2-7. Mass balance of CaO-treated PCE under different experimental conditions. In the X-axis labels, “He” indicates the helium-purged condition, and “Air” indicates a reaction condition without purging helium. :1” indicates when the ratio of CaO to H 2 O is 1:1 and :2” when it is 1:2. Y-axis is % of byproducts (PCE, TCE, and Cl ) and unknown. The percent of TCE and Cl was negligible on the plot. The portion of TCE was 0.23 %, 0.21 %, 0.1 % and 0.05 %, and that of Cl was 0.011 %, 0.006 %, 0.010 %, 0.007 % at He-1:1, He-1:2, Air-1:1, and Air-1:2, respectively. 52

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He-1:1He-1:2Air-1:1Air-1:2 recovery (%) 020406080100 Figure 2-8. Percent recoveries of TCE under different experimental conditions. In the X-axis labels, “He” indicates the helium-purged condition, and “Air” indicates a reaction condition without purging helium. :1” indicates when the ratio of CaO to H 2 O is 1:1 and :2” when it is 1:2. The error bars represent the standard deviation of three replicates. 53

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% relative intensity 30 40 50 60 70 80 90 100 110 0 50 100 50 100 354759949698 3547495961949698 Cl Cl 30 40 50 60 70 80 90 100 110 0 50 100 50 100 354759949698 3547495961949698 Cl Cl m/e A % relative intensity 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 0 50 100 50 100 3547598294129166 3547598294119131166 Cl Cl Cl Cl 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 0 50 100 50 100 3547598294129166 3547598294119131166 Cl Cl Cl Cl m/e B Figure 2-9. Electron-impact mass spectra of byproducts by CaO-treated TCE. A) DCA, B) PCE, C) hexachlorobutadiene, and D) CA. The spectra of an unknown byproduct compared to the spectra of a chemical in NIST library with head (unknown spectra) and tail (known spectra) manner. X-axis label, “m/e,” indicates mass-to-charge ratio. Y-axis is % of relative intensity. 54

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% relative intensity 40 60 80 100 120 140 160 180 200 220 240 260 0 50 100 50 100 478394106118143155190225260 47708293105118131141153190225260 Cl Cl Cl Cl Cl Cl 40 60 80 100 120 140 160 180 200 220 240 260 0 50 100 50 100 478394106118143155190225260 47708293105118131141153190225260 Cl Cl Cl Cl Cl Cl m/e C % relative intensity 30 34 38 42 46 50 54 58 62 66 70 0 50 100 50 100 3537 4759606162 474959606162 Cl 30 34 38 42 46 50 54 58 62 66 70 0 50 100 50 100 3537474959606162 4759606162 Cl m/e D Figure 2-9. Continued 55

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He-1:1He-1:2Air-1:1Air-1:2 DCA (mmol) 0.000.020.040.060.080.100.120.140.160.18 Figure 2-10. DCA in the CaO-treated TCE under different experimental conditions. In the X-axis labels, “He” indicates the helium-purged condition, and “Air” indicates a reaction condition without purging helium. :1” indicates when the ratio of CaO to H 2 O is 1:1 and :2” when it is 1:2. The error bars represent the standard deviation of three replicates. He-1:1He-1:2Air-1:1Air-1:2 PCE (mmol) 0.0000.0020.0040.0060.0080.010 Figure 2-11. PCE in the CaO-treated TCE under different experimental conditions. In the X-axis labels, “He” indicates the helium-purged condition, and “Air” indicates a reaction condition without purging helium. :1” indicates when the ratio of CaO to H 2 O is 1:1 and :2” when it is 1:2. The error bars represent the standard deviation of three replicates. 56

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He-1:1He-1:2Air-1:1Air-1:2 Cl(mmol) 0.00.20.40.60.81.01.21.4 Figure 2-12. Chloride extracted in the CaO-treated TCE under different experimental conditions. In the X-axis labels, “He” indicates the helium-purged condition, and “Air” indicates a reaction condition without purging helium. :1” indicates when the ratio of CaO to H 2 O is 1:1 and :2” when is 1:2. The error bars represent the standard deviation of three replicates. 57

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He-1:1He-1:2Air-1:1Air-1:2 % 020406080100 TCE DCA PCE Hexa CA Clunknown Figure 2-13. Mass balance of CaO treated TCE under different experimental conditions. In the X-axis labels, “He” indicates the helium-purged condition, and “Air” indicates a reaction condition without purging helium. :1” indicates when the ratio of CaO to H 2 O is 1:1 and :2” when it is 1:2. Y-axis is percent of byproducts (TCE, DCA, PCE, hexachlorobutadiene (Hexa), CA, and Cl ) and unknown. The percent of PCE, hexachlorobutadiene, and CA was negligible. The portion of PCE was 0.10 % and 0.95 % at He-1:1 and Air-1:1, respectively. The portion of hexachlorobutadiene and CA at Air-1:1 was 0.42 % and 0.01 %, respectively. 58

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He-1:1He-1:2Air-1:1Air-1:2 recovery (%) 020406080100 Figure 2-14. Percent recoveries of cis-DCE under different experimental conditions. In the X-axis labels, “He” indicates the helium-purged condition, and “Air” indicates a reaction condition without purging helium. :1” indicates when the ratio of CaO to H 2 O is 1:1 and :2” when it is 1:2. The error bars represent the standard deviation of three replicates. 59

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% relative intensity 30 34 38 42 46 50 54 58 62 66 70 0 50 100 50 100 3537 4759606162 474959606162 Cl 30 34 38 42 46 50 54 58 62 66 70 0 50 100 50 100 3537474959606162 4759606162 Cl m/e A % relative intensity 30 40 50 60 70 80 90 100 110 0 50 100 50 100 35476163949698100 354761639698100 H Cl H Cl 30 40 50 60 70 80 90 100 110 0 50 100 50 100 35476163949698100 354761639698100 H Cl H Cl m/e B Figure 2-15. Electron-impact mass spectra of byproducts by CaO treatedcis-DCE. A) CA, B) trans-DCE, C) TCE, and D) VC. The spectra of an unknown byproduct compared to the spectra of a chemical in NIST library with head (unknown spectra) and tail (known spectra) manner. X-axis label, “m/e,” indicates mass-to-charge ratio. Y-axis is percent of relative intensity. 60

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% relative intensity 40 50 60 70 80 90 100 110 120 130 140 0 50 100 50 100 476062959799130 4760626682959799130 Cl Cl Cl 40 50 60 70 80 90 100 110 120 130 140 0 50 100 50 100 476062959799130 4760626682959799130 Cl Cl Cl m/e C % relative intensity 60 61 62 63 64 65 66 67 68 69 70 0 50 100 50 100 616264 61626364 Cl 60 61 62 63 64 65 66 67 68 69 70 0 50 100 50 100 616264 61626364 Cl m/e D Figure 2-15. Continued 61

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He-1:1He-1:2Air-1:1Air-1:2 CA (mmol) 0.00.20.40.60.81.01.21.41.61.82.0 Figure 2-16. CA in the CaO-treated cis-DCE under different experimental conditions. In the X-axis labels “He” indicates the helium-purged condition, and “Air” indicates a reaction condition without purging helium. :1” indicates when the ratio of CaO to H 2 O is 1:1 and :2” when it is 1:2. The error bars represent the standard deviation of three replicates He-1:1He-1:2Air-1:1Air-1:2 trans-DCE (mmol) 0.000.020.040.060.080.100.12 Figure 2-17. trans-DCE in the CaO-treated cis-DCE under different experimental conditions. In the X-axis labels, “He” indicates the helium-purged condition, and “Air” indicates a reaction condition without purging helium. :1” indicates when the ratio of CaO to H 2 O is 1:1 and :2” when it is 1:2. The error bars represent the standard deviation of three replicates. 62

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He-1:1He-1:2Air-1:1Air-1:2 TCE (mmol) 0.0000.0020.0040.0060.008 Figure 2-18. TCE in the CaO-treated cis-DCE under different experimental conditions. In the X-axis labels, “He” indicates the helium-purged condition, and “Air” indicates a reaction condition without purging helium. :1” indicates when the ratio of CaO to H 2 O is 1:1 and :2” when it is 1:2. The error bars represent the standard deviation of three replicates. He-1:1He-1:2Air-1:1Air-1:2 Cl(mmol) 0.00.20.40.60.81.01.2 Figure 2-19. Chloride extracted in the CaO-treated cis-DCE under different experimental conditions. In the X-axis labels, “He” indicates the helium-purged condition, and “Air” indicates a reaction condition without purging helium. :1” indicates when the ratio of CaO to H 2 O is 1:1 and :2” when it is 1:2. The error bars represent the standard deviation of three replicates. 63

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He-1:1He-1:2Air-1:1Air-1:2 % 020406080100120 cis-DCE trans-DCE CA TCE VC Cl unknown Figure 2-20. Mass balance of CaO-treated cis-DCE under different experimental conditions. In the X-axis labels, “He” indicates the helium-purged condition, and “Air” indicates a reaction condition without purging helium. :1” indicates when the ratio of CaO to H 2 O is 1:1 and :2” when it is 1:2. Y-axis is percent of byproducts (cis-DCE, trans-DCE, CA, TCE, and Cl ) and unknown. The percent of TCE was 0.37 %, 0.51 %, 0.53 %, and 0.45 % at He-1:1, He-1:2, Air-1:1 and Air-1:2, respectively. The percent of trans-DCA was 0.41 %, 0.21 %, 7.38 % and 0.26 % at He-1:1, He-1:2, Air-1:1 and Air-1:2, respectively. The portion of Cl was 0.30 % and 0.26 % at He-1:2 and Air-1:2, respectively. The portion of VC at Air-1:1 was 1.11 %. 64

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CHAPTER 3 IMPACTS OF TEMPERATURE AND TIME ON THE REACTION OF CALCIUM HYDROXIDE WITH TRICHLOROETHYLENE 3.1 Introduction The degradation of chlorinated ethylenes when CaO reacts with a chlorinated ethylene-water mixture was demonstrated in the previous chapter. The partial decomposition of selected chlorinated ethylenes was considered a result of the reaction of Ca(OH) 2 formed by the hydration of CaO with the chlorinated ethylenes. The decomposed products varied and depended upon the reaction environment, such as the presence of air and the amount of excess water for hydration. The predicted reaction of TCE in contact with Ca(OH) 2 and a consecutive reaction of Ca(OH) 2 and a byproduct (HCl) of TCE are presented as Eq. 3-1, Eq. 3-2 and Eq. 3-3. )()()(22)()(322gHClgClCgHClCsOHCa [3-1] )()()()()(222gOHsCaClsOHCagHCl [3-2] or )()()()()(22gOHsCaOHClsOHCagHCl [3-3] The reactants shown in Eq. 3-2 or Eq. 3-3 are gaseous reactants (TCE and HCl) and a solid reactant (Ca(OH) 2 ). Levelnspiel (1976) summarized intermediate steps in a common gas-solid reaction for spherical particles of unchanged size as follows: 1) diffusion of a gaseous reactant and a gaseous product through the bulk of the gas phase (the film surrounding the particle) to the surface of the solid, 2) penetration and diffusion of the reactant or gaseous products through the blanket of ash (solid product layer on the solid reactant’s surface) to the surface of the unreacted core, 3) reaction of the gaseous reactant with a solid at the reaction surface, 4) diffusion of gaseous products through the ash back to the exterior surface of the solid, and 5) diffusion of gaseous products from the gas film back to the main body of fluid. One of the given stages or combined stages can limit the rate of a gas-solid reaction. 65

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In the results observed in Chapter 2, Ca(OH) 2 consumed by the reaction of Ca(OH) 2 with HCl (which is formed by the reaction of TCE in the contact with Ca(OH) 2 ) was less than 1 % of the Ca(OH) 2 formed (based on the Cl/Ca ratio). There may be steps limiting the degradation of TCE in the presence of Ca(OH) 2 since the formation of dichloroacetylene (DCA, C 2 Cl 2 ) and HCl may decrease by the formation of a solid product layer on the Ca(OH) 2 . If there is no reaction between gaseous TCE and the product layer formed (CaOHCl or CaCl 2 ), gaseous TCE has to diffuse through the layer toward unreacted Ca(OH) 2 to form DCA and HCl. A limiting stage due to the formation of the product layer may result in decreasing the formation of DCA and HCl by the reaction of TCE in contact with Ca(OH) 2 . Reaction temperature can affect the formation of a product layer in a gas-solid reaction since the temperature influences the crystallization of the product layer (Duo et al., 1995). According to the theory introduced by Duo et al, a product layer with coarse crystals is formed at high temperature, but a dense product layer is formed at low temperature. The formation of a dense product layer on a solid reactant reduces the ability of the solid reactant to react with the gaseous reactant. Temperature rise caused by the hydration of CaO may affect the reactions of Eq. 3-1 and Eq. 3-2. However, the temperature peaks vary by the amount of hydrated CaO, the amount of water used, and the surrounding materials. The formation of decomposed TCE products with Ca(OH) 2 may rely on reaction temperatures and the formation of a solid product on the surface of Ca(OH) 2 . This study examined the conversion of TCE to organic byproducts and the formation of chloride when TCE was directly exposed to Ca(OH) 2 at different temperature. In addition, the changes of the formation of organic byproducts and chloride at different 66

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temperature and times were estimated by comparing the formation of DCA and extractable chloride. 3.2 Literature Review 3.2.1 Impact of Temperature on a Chemical Reaction. In general, a reaction rate () of product i can be described with a temperature-dependent term and a composition-dependent term as shown in Eq. 3-4 (Levenspiel, 1975). The dependency of a reaction rate on temperature () is expressed by Arrhenius’ law (Eq. 3-5). For example with the reaction of Ca(OH) ir k 2 to HCl, Yan et al. (2003) observed that increasing the temperature for the reaction of Ca(OH) 2 with HCl increased the initial reaction rate in the range of 170 230 o C. )()(21ncompositiofetemperaturfri [3-4] )(2ncompositiofk k = the reaction rate constant RTEekk/0 [3-5] k = reaction constant 0k = the frequency factor E = activation energy R = gas constant T = temperature The composition of reactants also affects the reaction rate. Increasing HCl concentration also enhances the rate of reaction between HCl and Ca(OH) 2 (Bausach et al., 2004, Yan et al., 2003). Bausach et al.(2004) reported that the reaction Ca(OH) 2 with HCl was a first-order reaction with respect to the HCl concentration (using a thermogravimetric analyzer (TGA) with 150 350 ppm at 120 o C and a relative humidity of 18 % for a 1000-second reaction time). However, Yan et al.(2003) observed that the initial reaction rate decreased when HCl concentration was over 1000 mg/m 3 under their experimental conditions. 67

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Assuming a chemical is at phase equilibrium between the pure condensed phase and gas phase, the change of temperature affects the concentration of the chemical in the gas phase. Increasing temperature increases vapor pressure (Eq. 3-6) and results in increasing the concentration of a chemical in the gas phase. Thermodynamically, the Clausius-Clapeyron equation describes the temperature dependency of vapor pressure from a pure liquid (Atkins, 1998). The increase in temperature changes the concentration of a compound in the gas phase exponentially, as shown in Eq. 3-7. In the case of the reaction of TCE in contact with Ca(OH) 2 , if TCE is present in a condensed phase and a gas phase, increasing temperature likely results in increasing TCE concentration in the gas phase. 2)(ln RT THdTpdvap [3-6] Hvap : the enthalpy of vaporization p : vapor pressure T : temperature (K) R : gas constant RTpVnCggg [3-7] gC : gas-phase concentration of the compound gn : mole of the compound in gas phase gV : volume of the gas p : vapor pressure 3.2.2 Conversion of Ca(OH) 2 to CaCl 2 (or CaOHCl) by the Reaction of Ca(OH) 2 with HCl In terms of a gas-solid reaction, the formation of DCA and HCl by the reaction of TCE in the contact with Ca(OH) 2 has rarely been studied, while several studies have been conducted on the formation of CaCl 2 or CaOHCl by the reaction of Ca(OH) 2 with HCl (Weinell et al., 1992; Fonseca, et al., 1998; Yan et al., 2003)). Yan et al. (2003) wrote that the formation of final products depended on the temperature and the length of the reaction. In their research, CaOHCl 68

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was the primary product with temperatures between 170 230 o C, but CaCl 2 was formed in the temperature range of 300 o C 350 o C with an extended reaction time. Allal et al.(1998) observed that CaCl 2 was fully converted to CaOHCl in the presence of Ca(OH) 2 . Thus, CaCl 2 formed by the reaction of Ca(OH) 2 with HCl can be converted to CaOHCl in the presence of unreacted Ca(OH) 2 . The percent of Ca(OH) 2 conversions to CaCl 2 or CaOHCl reported in the literature varied with temperatures and the presence of moisture. In general, the percent of Ca(OH) 2 conversion was low at low temperatures in the absence of water (around 5 % at 50 o C with a 2to 3-minute reaction time (Fonseca, et al.,1998), <10 %, below 150 o C within 500-1000 seconds (Weinell et al., 1992), 10 % at 170 o C within 100-200 minutes (Yan et al., 2003)). However, almost full conversion of slaked lime (Ca(OH) 2 ) in the presence of moisture was observed in a range of low temperatures (below 150 o C) (Weinell et al., 1992). Weinell et al. observed that the influence of moisture on the Ca(OH) 2 conversion decreased with increasing the temperature over 100 o C. 3.2.3 Impacts of Temperature on the Reaction of Ca(OH) 2 with HCl and Ultimate Conversion of Ca(OH) 2 to CaCl 2 /CaOHCl Duo et al. (1995) described the alteration of the reaction progress in the rate-limiting step for a solid-gas reaction of Ca-compounds with HCl. In the early stages, the growth of product crystals on the sorbent reduces the free surface of the sorbent for the reaction and results in decreasing the reaction rate. In the next stage, the diffusion of a gaseous reactant through the product layer controls the reaction rate. In the last stage, the reaction rate is reduced significantly by the decrease of the reactant diffusion through the growing product layer (Duo et al., 1995). Temperature also affects the ultimate conversion of Ca(OH) 2 to CaCl 2 /CaOHCl; however, the conversion depends on the presence of moisture and temperature. (Weinell et al., 1992; Fonseca et al., 1998; Yan et al., 2003). The Ca(OH) 2 conversion observed did not vary in the 69

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absence of water at temperature ranges between 50 o C and 125 o C after 20 minutes of reaction with 600 ppm HCl (Fonseca et al.,1998). However, Yan et al. observed a linear increase in the Ca(OH) 2 conversion from 170 o C to 300 o C. Duo et. al.(1995) described crystal growth of the solid product layer with a crystallization model to explain the dependency of the ultimate Ca(OH) 2 conversion on temperature. In their hypothesis, high Ca(OH) 2 conversion is allowed at high temperatures since high porosity of product layers occurs at high temperatures, as shown in Figure 3.1. However, the conversion of Ca(OH) 2 to CaCl 2 at low temperatures is low since low permeable product layers are formed due to smaller product crystals caused by insufficient product material at the low temperatures. 3.3 Methods and Materials 3.3.1 Reagents Trichloroethylene (Alfa Aesar, 99.5 %) and calcium hydroxide (Fisher Scientific, USP/FCC) were used for the reaction of calcium hydroxide with trichloroethylene in a test vessel. cis-1,2-dichloroethylene (Acros Organics, 97 %), tetrachloroethylene (Acros Organic, 99+ %), vinylidene chloride (Acros Organics, 99.9 %) and trans-1,2-dichloroethylene (Acros Organics, 98 %) were used to synthesize analytical standards and confirm the retention time of products in a chromatogram. 3.3.2 Reactions of TCE with Calcium Hydroxide at Different Temperatures For this experiment, the vessels shown in Figure 2-1 were used. Instead of loading Ca(OH) 2 in the Teflon plunger, 7.4 g of dry Ca(OH) 2 were added directly into the test vessel. To prevent Ca(OH) 2 from carbonating during drying due to airborne CO 2 , dry Ca(OH) 2 was obtained by heating in a glass tube at 110 ( 10) o C while flushing nitrogen gas (5.0 ultra-high-purity grade (UHP)) through the tube. The Teflon plunger was screwed down and helium was purged immediately through an uncapped side port. Helium was purged with a flow rate of 1200 70

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mL/min for approximately 20 minutes until 90 uL of TCE was spiked into the vessel. The side port was then sealed quickly by a cap with septum. The amount of calcium hydroxide and TCE used for an experiment was equivalent to 100 mmol and 1.0 mmol, respectively. The vessels containing Ca(OH) 2 and TCE were placed into an oven at the desired temperature. The test vessels were treated for 0.5 hour, 1 hour, 2 hours, 3 hours, and 5 hours. At 20 o C, treatment time was extended to 12 hours and 24 hours. These experiments were conducted in duplicate. The method used to collect reaction byproducts from the treated sample was identical to that used for the experiments described in Chapter 2 (Figure 2-3). The methanol extract in the vessel and the methanol in the traps were analyzed for the residual TCE and organic byproducts. The methanol extract in the vessel was analyzed for chloride as well. 3.3.3 Calculation of Ca(OH) 2 Conversion to CaCl 2 /CaOHCl The Cl/Ca ratio was calculated using the ratio of the mole of extracted chloride to the mole of initial Ca(OH) 2 added, as shown in Eq. 3.5. If the given quantity of TCE is completely decomposed to DCA and HCl and all the HCl react with Ca(OH) 2 to form CaCl 2 or CaOHCl, the ultimate value of Cl/Ca ratio is expected to be 0.01 (with 1 mmol TCE and 100 mmol Ca(OH) 2 ). The Cl/Ca ratio can be read as the dechlorination of TCE by Ca(OH) 2 . 2Ca(OH)initialofmolesproductsolidthefromextractedClofmolesratioCl/Ca [3.5] 3.3.4 Initial TCE Concentration in Gas Phase The initial TCE concentration in the gas phase at a given temperature was calculated using phase equilibrium at the given temperature. Assuming an ideal gas behavior of TCE and ignoring the amount of TCE adsorbed on particles, the TCE concentration in the gas phase was predicted using Eq. 3-6 and the vapor pressure at a given temperature. The sum of the volume of headspace and pore volume in 7.4 g Ca(OH) 2 was 113.7 mL. The vapor pressure used for TCE 71

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was 58 mmHg and 214.5 mmHg at 20 o C and 50 o C, respectively (Lide, 1996). The initial TCE concentration calculated in gas phase was 0.027 mmol/mL at 20 o C. An identical concentration, 0.0088 mmol/mL, was obtained at 60 o C, 80 o C, and 100 o C because TCE spiked was completely vaporized at 50 o C. 3.3.5 Analytical Method Chemicals collected in the extracts and traps were analyzed by gas chromatograph/mass spectrometry (GC/MS, Finnigan Trace 2000) equipped with a Rtx-VMS capillary column (Restek, 30 m in length, I.D. 0.32 mm) and a gas chromatograph/flame ionization detector (GC/FID, Hewlett Packard 5890 Series II) equipped with a DB-624 capillary column (Agilent Technologies, 30 m in length, I.D. 0.53 mm). The chloride in methanol and the water-extracts was analyzed with an ion chromatograph (DIONEX LC20 and CD20) operated with 1.20 mL/min of effluent flow rate through an anion column (Allsep Anion column, Alltech, Deerfield, Illinois, USA). Dichloroacetylene (DCA) and chloroacetylene (CA) were not quantified directly since commercial standards were not available. Greim et al. (1984) used 1,2-dichloroethylene with an analogous structure and estimated that the error may not exceed 50 %. For this research, DCA and CA were quantified using 1.2-dichloroethylene and vinyl chloride. 3.4 Results and Discussion 3.4.1 Amount of TCE Recovered after Ca(OH) 2 Treatment at Different Temperatures The amount of TCE recovered is shown in Figure 3-2 when TCE was exposed directly to Ca(OH) 2 with different temperature. The treatment was conducted for 5 hours at 60 o C, 80 o C, and 100 o C and for 12 hours at 20 o C. The rest of TCE not included in the TCE recovered perhaps consisted of TCE converted to byproducts and TCE that escaped during the experiment. The amount of TCE recovered decreased with increasing temperature of the treatment. However, 72

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the average amount of TCE recovered at 80 o C was close to that at 100 o C. TCE recovered was 0.76 ( 8.3 %) mmol at 80 o C and 0.76 ( 2.2 %) mmol at 100 o C. 3.4.2 Formation of Chloride of Ca(OH) 2 -treated TCE The levels of extracted chloride in the TCE treated by Ca(OH) 2 at different temperatures are shown in Figure 3-3. The amount of extracted chloride varied with the reaction temperature. The amount of extracted chloride increased with increasing temperature from 0.007 ( 52.1 %) mmol to 0.11 ( 1.6 %) mmol. In contrast to the amount of TCE recovered in samples treated at 80 o C and 100 o C, the amount of chloride extracted shows clear differences at the different temperatures. The amount of chloride extracted in the treated TCE was 0.06( 48.7 %) mmol at 80 o C and was 0.11 ( 1.6 %) mmol at 100 o C. The Cl/Ca ratio of treated samples is a measurement of the degree of Ca(OH) 2 conversion to CaCl 2 or CaOHCl. The Cl/Ca ratio of TCE treated with Ca(OH) 2 at 20 o C for a 12-hour treatment was 0.00007 ( 52 %). The Cl/Ca ratios of treated TCE at 60 o C, 80 o C, and 100 o C for a 5-hour treatment were 0.0004 ( 14 %), 0.0006 ( 48.7 %), and 0.0011 ( 1.6 %), respectively. Comparing these values to the maximum Cl/Ca ratio of 0.5/1.0 when Ca(OH) 2 converted completely to CaCl 2 /CaOHCl, the Ca(OH) 2 converted to CaCl 2 /CaOHCl under given reaction conditions did not exceed 0.22 %/0.11 % of Ca(OH) 2 added. Comparing the values of the Cl/Ca ratios found in literatures (0.5-0.1) at the temperature range of 50 – 170 o C for the reaction of Ca(OH) 2 with HCl, the observed Cl/Ca ratios in this study were considerably lower than the values reported. The low Cl/Ca values showed that most of the Ca(OH) 2 in the test vessel remained unreacted. These results suggest that the formation of CaCl 2 or CaOHCl at the a given temperature range likely was not limited by the reaction of Ca(OH) 2 with HCl but was limited by the formation of HCl by the dehydrochlorination of TCE with Ca(OH) 2 . 73

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3.4.3 Conversion of TCE to Organic Byproducts. The organic byproducts detected were DCA, chloroacetylene (CA), and perchloroethylene (PCE) when TCE was exposed to Ca(OH) 2 at different temperatures. The amounts of DCA formed are shown in Figure 3-4. The formation of DCA was increased with increasing temperature, but the differences among the amounts of DCA with different reaction temperatures were not as great as those of chloride with the same condition. When TCE was treated at 80 o C and 100 o C for 5 hours, the amounts of DCA formed were 0.047 ( 5.7 %) mmol and 0.048 ( 6.8 %) mmol, respectively. The formation of CA and PCE was observed at 60 o C, 80 o C, and 100 o C. The results of CA and PCE are summarized in Table 3-1. The amount of CA and PCE increased with increasing reaction temperature. Compared to the amount of DCA and Cl , the amounts of CA and PCE were trivial. None of the amounts of PCE and CA observed was larger than 0.5 mol. The large variations of PCE and CA concentrations in duplicate samples might indicate the presence of uncertainties. Notwithstanding the small amounts of CA and PCE, the formation of PCE and CA by the degradation of TCE contacting Ca(OH) 2 might suggest the presence of additional reactions among TCE, byproducts, and Ca(OH) 2 during the treatment. 3.4.4 Variation of the Mole Ratio of Cl Extracted to DCA. If the dehydrochlorination of TCE in contact with Ca(OH) 2 occurs, the reaction produces the same moles of DCA as those of HCl. If the source of Cl is only from HCl formed by the dehydrochlorination of TCE (Eq. 3-1), the Cl/DCA ratio should be constant regardless of the change of temperature and time. However, the value of the Cl/DCA ratio is not necessarily 1, since the DCA was quantified with 1,2-dichloroethylene (as discussed in Chapter 2). The mole ratio of Cl to DCA with different reaction temperatures is shown in Figure 3-5. A large variation of the Cl/DCA ratio was shown with different temperatures. The Cl/DCA ratios ranged from 74

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0.46 ( 46 %) to 2.31 ( 8 %). The ratios of the Cl/DCA increased with increasing reaction temperature. The variation of the Cl/DCA ratio indicated that HCl formed by TCE dehydrochlorination might not be the only source of the formation of Cl . Increasing Cl/DCA ratios with increasing temperature suggested that the additional sources of Cl increased. As discussed in the previous section, the increase of PCE and CA formed at high temperature suggested an increase in additional reactions. The additional reactions could be the additional source of the formation of Cl . The mechanisms of the additional reactions were not identified and further study is necessary to reveal the reaction mechanism. 3.4.5 Mass Balance of Treated TCE in the Contact with Ca(OH) 2 at Different Temperatures Mass balance was calculated using moles of chlorine in organic byproducts and moles of chloride by the same method conducted in Chapter 2. As Figure 3-5 shows, the percent of chlorine in the byproducts increased with increasing reaction temperatures. However, the sum of chlorine in organic and inorganic (chloride) byproducts did not exceed more than 7 % of total chlorine in the TCE spiked initially. The portion of unknown ranged from 5.8 % of 18 %. The percent of chlorine in the organic byproducts, including DCA, CA, and PCE, ranged from 1.0 % to 3.2 % of the total at the given temperature range. However, the percent of DCE at different temperatures did not vary as much, with 2.6 %, 3.1 %, and 3.2 % at 60 o C, 80 o C, and 100 o C, respectively. The percent of chlorine contributed by the formation of chloride increased clearly with increasing temperature. The percent of chloride was 0.2 %, 1.2 %, 2.1 %, and 3.7 % at 20 o C, 60 o C, 80 o C, and 100 o C, respectively. The results indicated that the percent of organic byproducts was greater than that of chloride extracted at low temperatures. In contrast, the percent of chloride extracted was greater than that of the organic byproducts at high temperatures. 75

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3.4.6 Impacts of Reaction Temperatures and Times on the transformation of TCE Figure 3-7 shows the amounts of TCE recovered, chloride extracted, and DCA formed at different reaction temperatures and times. The amount of TCE recovered decreased with increasing temperature and time (Figure 3-7 (A)), but the amounts of Cl extracted increased with increasing reaction time (Figure 3-7 (B)). Note that the scale for TCE is different from that for Cl in Figure 3-7. However, the degree of change in TCE reduction and Cl formation decreased significantly after 1 hour, 2 hours, and 3 hours of reaction time at 100 o C, 80 o C, and 60 o C, respectively. The amount of DCA increased with increasing reaction temperature but did not vary over reaction time. The amount of DCA was stable or decreased slightly over extended reaction times. The formation of DCA in the beginning of the reaction could be the result of the large unreacted surface area of Ca(OH) 2 . However, the decreasing free surface of Ca(OH) 2 and the formation of a product layer on the Ca(OH) 2 could cause the formation of DCA to decrease. The increase of the formation of DCA with increasing reaction temperature could be explained by the crystal growth model addressed by Duo et al.(1995). The Cl/DCA ratios with different reaction temperatures and reaction times are shown in Figure 3-8. The Cl/DCA ratios varied at different temperatures as well as reaction times. The Cl/DCA ratios ranged from 0.37 to 0.92 at 60 o C and from 1.6 to 2.4 at 100 o C for 5 hours. The variation of the Cl/DCA ratio over time suggested a feasible mechanism for determining the fate of TCE: at the beginning of the degradation of TCE contacting Ca(OH) 2 , a large amount of DCA and HCl is produced by dehydrochlorination of TCE. The HCl formed reacts with Ca(OH) 2 to form CaCl 2 (CaOHCl). The continuous formation and degradation of DCA result in a relatively constant amount of DCA. In this scenario, the dehydrochlorination of TCE continues while the DCA decomposes simultaneously. A part of the decomposed products of DCA reacts with 76

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Ca(OH) 2 to form additional CaCl 2 or CaOHCl. Further growth of the product layer on the surface of Ca(OH) 2 hinders the formation of DCA and HCl and results in the constant or slightly reduced amount of DCA. The formation of chloride (CaCl2 or CaOHCl) may be continued but ultimately stops when the growth of the additional product layer on the Ca(OH) 2 is enough to prevent the gaseous reactants (TCE, decomposed DCA products, or HCl) from contacting unreacted Ca(OH) 2 . The presence of other organic byproducts at different temperatures and times is summarized in Table 3-2 for CA and Table 3-3 for PCE. The amount of CA and PCE increased with increasing reaction time and reaction temperature. The quantities of PCE and CA were negligible comparing those of TCE, DCA, or chloride extracted. However, despite the formation of trivial amounts of CA and PCE, the formation of PCE and CA during TCE-Ca(OH) 2 reaction suggested the presence of other unknown reactions. 3.5 Summary and Conclusions Hydration of CaO in the presence of TCE caused the destruction of TCE to form C 2 Cl 2 and HCl. The temperature of the CaO hydration may vary by the amount of CaO hydrated and the surrounding materials. It is essential to understand the impact of temperature on the reaction of TCE in contact with Ca(OH) 2 to interpret and predict TCE decomposition during CaO hydration. This chapter detailed the impacts of reaction temperature and time on the formation of organic and inorganic byproducts when TCE is exposed to Ca(OH) 2 . The degree of TCE transformation to byproducts increased with increasing temperature when TCE was exposed to Ca(OH) 2 . The formation of chloride extracted increased with increasing temperature. Notwithstanding the trivial amount of TCE converted to byproducts at 20 o C, the results indicated that TCE can be degraded by dry Ca(OH) 2 at the range of ambient temperatures. The estimated degree of Ca(OH) 2 conversion using the Cl/Ca ratio revealed that 77

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most of the Ca(OH) 2 in the test vessel remained in the unreacted state. These results suggested that the reaction of Ca(OH) 2 with HCl (formed by the dehydrochlorination of TCE with Ca(OH) 2 ) might be hindered. DCA, CA, and PCE were detected when TCE was exposed to Ca(OH) 2 at different temperatures. The formation of CA and PCE increased with increasing reaction temperature. The formation of DCA increased with increasing temperature but the amount of DCA did not show a great difference at different temperatures. Even though the amounts of CA and PCE were trivial compared to those of DCA, the formation of CA and PCE is important because these results may indicate the presence of other reactions, such as the degradation of DCA. The results of mass balance calculations showed that the percent of organic byproducts ranged from 1.0 % to 3.2 % of TCE spiked. The percent of chloride ranged from 0.2 % to 3.7 % at different temperatures. The percent of organic byproducts was greater than that of the chloride at low temperatures, but the percent of chloride exceeded that of organic byproducts at high temperatures. The transformation of TCE and the formation of byproducts were influenced not only by different temperatures but also by different reaction times. However, the amount of DCA increased with increasing the reaction temperature but did not vary with reaction time. The variation of the Cl/DCA ratios at different temperatures and times indicated that the formation of CaCl 2 (or CaOHCl) might depend not only on HCl but also on other unknown byproducts and reaction. 78

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Table 3-1. Chloroacetylene (CA) and PCE at the end of the treatment at 20 o C, 60 o C, 80 o C, and 100 o C. Treated Temperature ( o C) Product 20 60 80 100 CA ND 0.012 ( 131 %) 0.017 ( 21 %) 0.068 ( 18 %) PCE ND 0.028 ( 132 %) 0.108 ( 119 %) 0.301 ( 25 %) Unit is micromole (mol). ND indicates that the concentration of a solvent sample was under the detection limit (10 g/L). The values in parenthesis indicate relative percent difference (RPD (%) = 100 [(x 1 -x 2 )/ {(x 1+ x 2 )/2}]). TCE was treated at 20 o C for 12 hours and at other temperatures for 5 hours. Table 3-2. Chloroacetylene (CA) in treated samples at 20 o C, 60 o C, 80 o C, and 100 o C. Treated Temperature ( o C) Time (hours) 20 60 80 100 0.5 a 0.001 (NA b ) 0.070 ( 22 %) 1.0 ND 0.005 ( 17 %) 0.144 ( 24 %) 2.0 0.001 (NA) 0.007 ( 14 %) 0.044 ( 21 %) 3.0 0.006 (NA) 0.009 ( 9 %) 0.042 ( 44 %) 5.0 0.012 ( 131 %) 0.017 ( 21 %) 0.068 ( 18 %) 12.0 ND c 24.0 ND Unit is micromole (mol). a : “-” represents that an experiment was not conducted. b : NA indicates “not available” since a concentration of CA for a sample was under the detection limit. c: ND indicates that the concentration of a sample was under the detection limit (10 g/L). The values in parenthesis represent relative percent difference (RPD (%) = 100 [(x 1 -x 2 )/ {(x 1+ x 2 )/2}]). Table 3-3. PCE in treated samples at 20 o C, 60 o C, 80 o C, and 100 o C Treated Temperature (oC) Time (hours) 20 60 80 100 0.5 a 0.006 (NA b ) 0.047 ( 123 %) 1.0 ND c ND 0.025 (NA) 2.0 ND 0.063 ( 112 %) 0.068 ( 82 %) 3.0 0.008 (NA) 0.024 ( 3 %) 0.055 ( 16 %) 5.0 0.028 ( 132 %) 0.108 ( 119 %) 0.301 ( 25 %) 12.0 ND 24.0 ND Unit is micromole (mol). a : “-” represents that an experiment was not conducted. b : NA indicates “not available” since a concentration of CA for a sample was under the detection limit. c: ND indicates that the concentration of a sample was under the detection limit (10 g/L). The values in parenthesis represent relative percent difference (RPD (%) = 100 [(x 1 -x 2 )/ {(x 1+ x 2 )/2}]). 79

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gas gas product layer product layer (1)(2)(3)(b)(a)sorbentsorbenttime gas gas product layer product layer (1)(2)(3)(b)(a)sorbentsorbenttime Figure 3-1. Schematic presentation of the structure of the product layers: (a) higher conversion allowed at higher temperatures and (b) only lower conversion allowed at lower temperatures. The solid curve represents the current position of the reaction interface; the dashed curve represents the initial position of the particle surface (Duo et al., 1995). temperature (oC) 206080100 TCE (mmol) 0.000.200.700.750.800.850.900.951.00 Figure 3-2. TCE recovered after Ca(OH) 2 treatment with different temperatures. TCE was treated at 20 o C for 12 hours and at the other temperatures for 5 hours. Error bars indicate two different values in duplicate. 80

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temperature (oC) 206080100 Cl(mmol) 0.000.020.040.060.080.100.12 Figure 3-3. Chloride extracted after Ca(OH) 2 treatment at different temperatures. TCE was treated at 20 o C for 12 hours and at other temperatures for 5 hours. Error bars indicate two different values in duplicate. temperature (oC) 206080100 DCA (mmol) 0.000.010.020.030.040.050.06 Figure 3-4. DCA after Ca(OH) 2 treatment at different temperatures. TCE was treated at 20 o C for 12 hours and at other temperatures for 5 hours. Error bars indicate two different values in duplicate. 81

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temperature (oC) 206080100 Cl/DCA (mmol/mmol) 0.00.51.01.52.02.53.0 Figure 3-5. Mole ratios of Cl to DCA by the Ca(OH) 2 treatment with different temperatures. TCE was treated at 20 o C for 12 hours and at other temperatures for 5 hours. Error bars indicate two different values in duplicate. 82

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temperature (oC) 206080100 % 01020707580859095100 TCE unknown DCA Cl PCE CA Figure 3-6. Mass balance of chorine using moles of chlorine in the byproducts after the degradation of TCE contacting Ca(OH) 2 at different temperatures. TCE was treated at 20 o C for 12 hours and at other temperatures for 5 hours. The Y-axis indicates the percent of byproducts and unknown. The percents of CA and PCE were negligible. 83

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time (hour) 0123456TCE (mmol) 0.50.60.70.80.91.01.11.2 101214161820222426 60 oC 80 oC 100 oC 20 oC A time (hour) 0123456Cl (mmol) 0.000.020.040.060.080.100.120.14 101214161820222426 60 oC 80 oC 100 oC 20 oC B Figure 3-7. TCE, Cl , and DCA in the degradation of TCE contacting Ca(OH) 2 at different temperatures and times. A) TCE, B) Cl, and C) DCA. The X-axis at the top is only for 20 o C and the X-axis at the bottom is for 60 o C, 80 o C, and 100 o C. Error bars indicate two different values in duplicate. 84

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time (hour) 012345DCA (mmol) 6 0.000.010.020.030.040.050.060.07 101214161820222426 60 oC 80 oC 100 oC 20 oC C Figure 3-7. Continued time (hour) 012345 6 Cl/DCA (mmol/mmol) 0.00.51.01.52.02.53.0 60 oC 80 oC 100 oC Figure 3-8. Mole ratios of Cl to DCA with different temperatures and times. Error bars indicate two different values in duplicate. 85

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CHAPTER 4 TRANSFORMATION OF CHLORINATED ETHYLENES IN SOIL BY THE ADDITION OF CALCIUM OXIDE 4.1 Introduction Chlorinated ethylenes are common contaminants found in groundwater and soil. The chlorinated ethylenes include tetrachloroethylene (PCE), trichloroethylene (TCE) and dichloroethylenes (DCEs), and vinyl chloride (VC). The remediation of chlorinated ethylene-contaminated soil in situ is expensive in terms of time and cost since chlorinated ethylenes are dense non-aqueous-phase liquids (DNAPLs). Excavating DNAPLs-contaminated soil, if applicable, is often necessary to remove the source of groundwater contamination. Applying quicklime improves physical properties of fine-grained soils by adjusting the water content and flocculating soil particles (NLA, 2004). Quicklime may also be added as part of soil cleanup operations to create a more favorable physical soil condition (FDOT, 2002). When a clayey soil is mixed with quicklime, the soil undergoes a rapid cation exchange and a flocculation-agglomeration process that clumps particles together. The flocculation of clay particles is caused by the electrolyte concentration increased in water in the soil and the adsorption of calcium cation on the clay surface (TRB, 1987). When quicklime is added to a soil, CaO in the quicklime reacts with water in the soil and the reaction results in forming calcium hydroxide (Ca(OH) 2 ). This reaction is exothermic and is a part of the slaking processes. The slaking processes include the hydration of CaO and the dissolution of Ca(OH) 2 in water as shown in Eq. 4-1 and Eq. 4-2. The heat liberated by the hydration of CaO is -65.2 kJmol -1 and by the dissolution of Ca(OH) 2 is -16.3 kJ mol -1 (Ritchie and Bing-an, 1990). The second reaction may not be important when quicklime is added to unsaturated soil because the amount of Ca(OH) 2 dissolved in the water is negligible. Ca(OH) 2 formed in the quicklime-mixed soil can be carbonated if sufficient CO 2 is present in the air in the quicklime-mixed soil (Eq. 4-3). 86

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However, the third reaction may be limited due to the lack of airborne CO 2 flux to Ca(OH) 2 in the quicklime-mixed soil. 22)(OHCaOHCaO )/58.15(/2.65molekcalmolekJH [4-1] OHCaOHCa2)(22 )/89.3(/3.16molekcalmolekJH [4-2] OHCaCOCOOHCa2322)( )/28.22(/29.93molekcalmolekJH [4-3] In spite of frequent uses of quicklime in field projects, the thermal properties of CaO-added soil has been rarely reported. The progress of the hydration of CaO added to a wet soil may differ from that in free water. In the soil environment, water that is available for the hydration of the added CaO, referred to below as “available water,” may not be sufficient at the beginning of the hydration. Since the remaining water may be trapped among the soil particles (in soil aggregates) in the beginning of hydration, the water cannot directly contact the added CaO. Thus, the progress of the hydration of CaO in the wet soil may be slower than that in free water if the available water in the soil is not enough to hydrate the added CaO at the beginning of the reaction. The obstruction in the soil environment for the hydration of CaO may result in a slow temperature rise. When CaO reacted with chlorinated ethylene-water mixtures, the chlorinated ethylenes underwent the dehydrochlorination as discussed in Chapter 2. The transformation of chlorinated ethylenes varied under different reaction conditions, such as the amount of excess water for the hydration, the presence and absence of air, and temperature. Dehydrochlorination of TCE and cis-DCE in contact with Ca(OH) 2 results in the formation of hydrogen chloride (HCl). Hydrogen chloride reacts with Ca(OH) 2 to form CaCl 2 or CaOHCl and water. Ca(OH)Cl is known as a final 87

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product in the solid phase when CaCl 2 is in the presence of Ca(OH) 2 (Allal et al., 1998). The dehydrochlorination of cis-DCE and TCE contacting Ca(OH) 2 and the reaction of Ca(OH) 2 with HCl are shown from Eq. 4-4 to Eq. 4-7. HClHClCClHCOHCa2)(2222 [4-4] HClClCHClCOHCa22)(322 [4-5] OHCaClOHCaHCl2222)(2 [4-6] OHCaOHClOHCaHCl22)( [4-7] If a chlorinated ethylene is dechlorinated when CaO is added to a chlorinated ethylene-contaminated soil, the dechlorination progress of the chlorinated ethylene may be affected by the progress of the hydration of CaO added in the soil environment. Temperature rise in a CaO-added soil may be influenced by the amount of water and CaO added in the soil. In addition, the temperature rise may affect the dechlorination of the chlorinated ethylene in the CaO-treated soil. The different temperatures generated in soils with different amounts of CaO affect the concentration of a chlorinated ethylene in air in the soils. Increasing the vapor pressure of a compound by elevating the temperature results in increasing the concentration of the compound in the gas phase. The concentration of a compound in the gas phase at phase equilibrium can be estimated by using vapor pressure at an equilibrium temperature with Eq. 4-8. Vapor pressures of chlorinated ethylenes with temperature are shown in Figure 4-1. The dechlorination of chlorinated ethylenes in contact with Ca(OH) 2 is also affected by the concentrations of chlorinated ethylenes in the gas phase as well as temperature. RTpVnCggg [4-8] gC : the gas phase concentration of the compound 88

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gn : moles of the compound in gas phase gV : the volume of the gas R : gas constant T : temperature (K) p : vapor pressure In this study dechlorination of chlorinated ethylenes in soil by the addition of CaO was explored with different amounts of CaO. First, temperature rises of soils were measured with the different mole ratios of CaO to H 2 O. Second, the extent of dechlorination of chlorinated ethylenes in the CaO-treated soils was determined by measuring the amount of chloride extracted from the treated soils. Finally, the maximum temperatures measured in CaO-treated soils were compared to the levels of chloride extracted from the CaO-treated soils. 4.2 Methods and Materials 4.2.1 Soils Coarse sand and loamy sand were used for this experiment. Coarse sand was purchased from a local home improvement store, and loamy sand was collected from a site at Fairbanks, Florida, USA. Particle size distributions of the soils are presented in Figure 4-2. Clay content of the coarse sand was negligible but that of loamy sands was 12 %. All soil samples were dried in an oven at 105 o C before use. 4.2.2 Reagents cis-1,2-dichloroethylene (Acros Organics, 97 %), trichloroethylene (Alfa Aesar, 99.5 %), and tetrachloroethylene (Acros Organics, 99+ %) were used to synthesize contaminated soils. Calcium oxide (Fisher Scientific, certified grade) was used to treat the synthesized soils. Sodium chloride (Fisher Scientific, certified ACS) was used to synthesize an analytical standard for chloride analysis. 89

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4.2.3 Temperature Measurement in CaO-added Soils Forty-two-milliliter-capacity VOA vials with open-top screw-caps and Teflon-coated septa (Fisher Scientific, Pittsburgh, Pennsylvania, USA) were used for the experiments. In each VOA vial, 20 g of a dry soil was added. Water content () of the soil in the VOA vial was adjusted by adding chlorine-free water. Water contents () used for the experiments were 5 % and 10 %. A known amount of CaO was added to a water-content-adjusted soil. The mole ratios of CaO to H 2 O used to treat a soil were 0.5, 1.0, and 1.5. The CaO-added soil was mixed well by a touch mixer (Model 231, Fisher Scientific, Pittsburgh, Pennsylvania, USA). After CaO was mixed with the soil, a temperature probe was inserted quickly through the septum of the VOA vial and the vial was placed into an insulated box. An Oakton thermometer (Melbourne, Australia) with a temperature metal-probe was used to measure temperature by the hydration of CaO in the soil. The change in temperature was measured until the CaO-treated soils in the VOA vials cooled down to room temperature range (23 2 o C). The experimental parameters used for this experiment are summarized in Table 4.1. 4.2.4 Synthesizing Contaminated Soils and CaO Addition Before CaO was added, a known amount of a contaminant (cis-DCE, TCE, or PCE) was spiked into the soils of which water content was adjusted. The volume of a spiked contaminant was 100 L, which is equivalent to 1.3, 1.1, and 1.0 mmol of cis-DCE, TCE and PCE, respectively. The addition of CaO into a chlorinated ethylene-contaminated soil was conducted using the same method as that used to measure the change of temperature during hydration of CaO. The mole ratios of CaO to H 2 O used to treat a soil were the same as those used to measure temperature. After CaO was added to a chlorinated ethylene-contaminated soil, the VOA vial was capped immediately. The CaO added was well mixed with the soil and the CaO-treated soils were stored in an insulated box for 24 hours. After the CaO treatment, water-soluble chloride 90

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was extracted by adding 30 ml of chloride-free water to the VOA vials and rotating them for 12 hours. To measure the background level of chloride in the soil and the CaO used, water-soluble chloride was extracted from a blank control in which a chlorinated ethylene was not spiked. 4.2.5 Analytical Method The water extracts were analyzed for chloride with an ion chromatograph (IC, DIONEX LC20 and CD20, Sunnyvale, California, USA). The I.C. was operated with 1.20 mL/min of effluent flow rate through an anion column (Allsep Anion, Alltech, Deerfield, Illinois, USA). A background concentration of chloride in a CaO-treated blank control was subtracted from that in the chlorinated ethylene-contaminated soil treated with the same amount of CaO. The method detection limit of chloride in the water extract was 30 g/L. 4.3 Results and Discussion 4.3.1 Temperature Dynamics during the Hydration of CaO Figure 4-3 shows the changes of temperature in coarse sand (Figure 4-3 left column) and loamy sand (Figure 4-3 right column) with the different CaO/H 2 O ratios. Temperature in the CaO-treated soils increased quickly in the first few minutes and reached the highest peak around 10 minutes, except 5 % loamy sand. In 5 % loamy sand, temperature increased slowly and blunt peaks of temperatures appeared with all the CaO/H 2 O ratios used. Comparing the change of temperature in coarse sand with that in loamy sand, the maximum temperatures achieved with different CaO/H 2 O ratios in coarse sand were greater than those in loamy sand under the same experimental conditions. In addition, the time to achieve the temperature peaks in the coarse sand was less than that in the loamy sand. However, the difference between the maximum temperature in the coarse sand and that in the loamy sand decreased with increasing the amount of CaO added and water content. Maximum temperatures 91

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measured in the treated materials with the different CaO/H 2 O ratios and different water contents are shown in Table 4-2. Comparing temperature rises by adding CaO to the 5 % soils with 10 % soils, the increase of temperatures in 5 % soils (coarse and loamy sand) was slower than in those with 10 % (Figure 4-2). Apparently, more hydration of CaO generated more heat to increase the temperature of the CaO-treated materials. Comparing the temperature rise of a 5 % soil treated with the CaO/H 2 O of 1.0 to that of a 10 % soil treated with the CaO/H 2 O ratio of 0.5 (the same amount of CaO was used in those soils), temperature peak appeared earlier in the CaO-treated 10 % soil than in the CaO-treated 5 % . This observation indicated that the additional water available for the hydration of CaO in a soil with high water content caused a rapid increase in the temperature of the CaO-added soil. The adverse effect of the lack of initially available water for the hydration of CaO on the temperature rise was significant in 5 % loamy sand. However, temperature rise in 10 % loamy sand treated with CaO was close to that with 10 % coarse sand as demonstrated by the similarity in temperature changes with 10 % coarse sand (Figure 4-3 (C) and (D)). These results suggested that the hydration of CaO in a CaO-added soil likely progressed with intermediate steps. In the first step, since the CaO added does not fully contact all water in the soil, a part of the CaO reacts only with water contacting the part of the CaO. Heat is generated by the hydration of the part of the CaO and the heat increases temperature of the CaO-added soil. In the next stage, humidity (vaporized water) in the air of the CaO-added soil increases since water trapped among soil particles is vaporized at an elevated temperature. In the following step, if unreacted CaO remains in the soil, any additional hydration of the CaO occurs and temperature of the CaO-added soil also increases. The additional hydration of CaO with the 92

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vaporized water is likely accelerated at the elevated temperature. Heat generated in the last stage increases humidity in the air in the CaO-added soil more. These steps are repeated in turn until water in soil or the added CaO is consumed completely. If a soil has enough available water (high water content) for the hydration of an added CaO in the beginning of the hydration of CaO, the progress of the hydration of CaO will be accelerated because the greater heat production in the first step causes a greater amount of vaporized water to form. Consequently, the temperature rise of the CaO-added soil will be accelerated. 4.3.2 Dechlorination of Chlorinated Ethylenes in the CaO-added Soils Dechlorination of chlorinated ethylenes in CaO-added soils varied with types of chlorinated ethylenes, the amounts of CaO added, initial water contents of soils, and types of soils. Figure 4-4 shows the total amount of chloride extracted in the CaO-added soils as a function of the CaO/H 2 O ratio. cis-DCE-contaminated and TCE-contaminated soils showed considerable amounts of chloride formation in the soils after the CaO treatment. In contrast, PCE-contaminated soils showed a negligible amount of chlorides by the CaO treatment. The maximum formation of chloride in CaO-treated chlorinated ethylenes was observed in 10 % coarse sand with the CaO/H 2 O ratio of 1.5. The maximum amounts of chloride in the cis-DCE-, TCE-, and PCE-contaminated soils were 1.11 mmol, 0.97 mmol, and 0.15 mmol, respectively. With the maximum formation of chloride, the percent of chlorine contributed to dechlorination was 43 %, 29 %, and 4 % of the chlorine in cis-DCE, TCE, and PCE spiked, respectively. Levels of chloride in the treated soils increased by increasing the amount of CaO added. Levels of chloride in the CaO-treated soils (both soil types) with 10 % were two to three times higher than those with 5 % . Note that with the same CaO/H 2 O ratios, the amount of CaO added in 10 % soils is twice as much as in 5 % soils. However, the dechlorination of chlorinated ethylenes was negligible in the presence of excess water with the CaO/H 2 O ratio of 93

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0.5. The presence of excess water that was more than that needed to hydrate added CaO likely retarded dechlorination of chlorine ethylenes as discussed in Chapter 2. The decrease of dechlorination of chlorinated ethylene in the presence of the excess water was thought to be caused by the competition between vaporized chlorinated ethylenes and water vapor to adsorb to the surface of Ca(OH) 2 . Once water vapor absorbs on the surface of Ca(OH) 2 with strong affinity between water and Ca(OH) 2 , chloroethylene vapors have to be dissolved into the water film on the surface of Ca(OH) 2 to contact Ca(OH) 2 . Comparing dechlorination of chlorinated ethylenes in coarse sand with that in loamy sand with the same amount of CaO, levels of chloride in the CaO-treated coarse sand were higher than those in the CaO-treated loamy sand. The different dechlorination of chlorinated ethylenes in the treated coarse sand and in the treated loamy sand was thought to be caused by different temperature rises in the two soils. 4.3.3 Dechlorination of cis-DCE and TCE and the Maximum Temperatures Achieved in the CaO-added soils Dechlorination of PCE was not included in this section because levels of chloride in CaO-treated PCE were negligible over most temperature ranges. Since the amounts of Ca(OH) 2 formed with the different CaO/H 2 O ratios varied, the mole ratio of extracted chloride to Ca(OH) 2 (Cl/Ca ratio) was used to express the amount of extracted chloride per the unit amount of Ca(OH) 2 . Figure 4-5 shows the Cl/Ca ratios in cis-DCEand TCE-contaminated soils as a function of the maximum temperatures. In Chapter 3, the impact of temperature on the degree of dechlorination of TCE was discussed when TCE was exposed to Ca(OH) 2 . The dechlorination of TCE with the Ca(OH) 2 was enhanced as temperature increased. The dechlorination of cis-DCE and TCE in the CaO added soils was also enhanced as the maximum temperature observed in the CaO-treated soils increased. 94

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To analyze the impact of interrelated factors on the dechlorination of chlorinated ethylenes, a plot in Figure 4-5 was divided into three regions (A, B, and C) using the number of influential factors relating to the dechlorination of chlorinated ethylenes. The influential factors used to decide the three regions were the presence of excess water for the hydration of CaO added, the concentration of a chlorinated ethylene in the gas phase, and temperature. The concentration of a chlorinated ethylene in the gas phase apparently increases as temperature increases until the spiked chlorinated ethylene is vaporized completely. Using Eq. 4-8 and assuming phase equilibrium with a pure substance, all cis-DCE spiked was vaporized at 63 o C as was TCE at 87 o C. Dechlorination of chlorinated ethylenes, as expressed with the Cl/Ca ratios, in Region A is affected by three influential factors: the presence of excess water (with the CaO/H 2 O ratio of 0.5), chlorinated ethylene concentrations in gas phase, and temperature. In this region, concentration of a chlorinated ethylene increased with increasing temperature. In Region A, the Cl/Ca ratio increased with increasing temperature. However, the degree of the dechlorination of chlorinated ethylenes was negligible since the impact of excess water for the hydration of CaO on dechlorination was dominant. In Region B, the Cl/Ca ratio was influenced by two influential factors: chlorinated ethylene concentrations in gas phase and temperature. Dechlorination of chlorinated ethylenes increased rapidly with increasing temperature in Region B since by increasing temperature, chlorinated ethylene concentrations in gas phase increased and the reaction for dechlorination of the chlorinated ethylene with Ca(OH) 2 was enhanced (discussed in Chapter 3). No water remains after the hydration of the added CaO in Region B. Finally, in Region C, the dechlorination is influenced by one influential factor, temperature. A chlorinated ethylene spiked is completely vaporized in the gas phase in Region C and there is no change of 95

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the concentration of a chlorinated ethylene with increasing temperature. In Region C, the increase in dechlorination of chlorinated ethylenes slows down as temperature increases. Retardation of the dechlorination may occur when a product layer forms on Ca(OH) 2 . The impact of a product layer on Ca(OH) 2 on the dechlorination progress of TCE was discussed in Chapter 3. 4.3.3 Implication and Limitations In remediating a contaminated soil, the increasing toxic effect during the remediation process should be reduced. The formation of toxic organic chemicals and dechlorination of chlorinated ethylenes from CaO-treated chlorinated ethylenes was demonstrated in Chapters 2 and 3. Dechlorination of chlorinated ethylenes in CaO-treated soils implied that destruction of the chlorinated ethylenes occurred in the CaO-treated soils. It also implied that toxic organic byproducts, such as chloroacetylene and dichloroacetylene, likely formed as well. However, since the presence of excess water for the hydration of CaO in soil greatly reduced dechlorination of chlorinated ethylenes, the formation of organic byproducts and dechlorination of chlorinated ethylenes can be reduced if enough water is present in a soil before CaO addition. The results of the experiments conducted in this study are not sufficient to predict dechlorination of chlorinated ethylenes under dynamic conditions, such as heat transportation and volatilization of the chemicals. Dechlorination of chlorinated ethylenes in CaO-added soil under field conditions may decrease since heat generated by the CaO hydration may be transferred to surrounding materials. In addition, if chlorinated ethylenes are volatilized by the addition of CaO and removed from the CaO-added soil, dechlorination of chlorinated ethylenes is likely reduced because the amount of reactant for the reaction decreases. 96

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4.4 Summary and Conclusions In this chapter, the impact of CaO addition in chlorinated ethylenes-contaminated soils was studied with different amounts of CaO, the presence of excess water for the hydration of CaO, temperature rises in the CaO-treated soils, and types of chlorinated ethylenes. The results are summarized below. Soil temperature increased quickly by CaO addition but varied with the amounts of CaO, moisture content of soils, and types of soils. The temperature peaks in coarse sand were higher and occurred earlier than those in loamy sand when the same amount of CaO was added. However, the difference of temperature rise between coarse sand and loamy sand was reduced when a great amount of CaO was added with high water content. It was thought that the amount of available water for the hydration of CaO added in soil significantly influenced the progress of the hydration. The levels of chloride detected in treated soils varied with the amounts of CaO, the types of chlorinated ethylenes, initial water content, and types of soils used. The degree of dechlorination of chlorinated ethylenes increased by increasing the CaO/H 2 O ratio. With the maximum dechlorination observed in this experiment, the percent of chlorine contributed to dechlorination was estimated as 43 %, 29 %, and 4 % of the chlorine in the spiked cis-DCE, TCE, and PCE, respectively. However, dechlorination of chlorinated ethylenes by CaO addition was reduced dramatically in the presence of excess water for the hydration of the CaO added with the CaO/H 2 O ratio of 0.5. The dechlorination of chlorinated ethylenes in CaO-added coarse sand was more prominent than in CaO-added loamy sand. The different degree of the dechlorination of a chlorinated ethylene in coarse sand and in loamy sand was likely caused by the different temperature rises in the two soils. 97

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Dechlorination of chloroethylene was affected integrally by several factors: the presence of excess water for the hydration of added CaO, the concentration of chlorinated ethylenes in the gas phase, and temperature. The factors were interrelated: the CaO/H 2 O ratio affected temperature rise, an elevated temperature increased the concentration of a chlorinated ethylene in the gas phase. The concentration of the chlorinated ethylene in the gas phase and temperature affected the dechlorination of the chlorinated ethylenes. Since this closed batch test does not represent dynamic field conditions such as volatilization of chlorinated ethylenes and heat transfer, the results in this study have limitations in assessing dechlorination of chlorinated ethylenes by CaO-treatment under field conditions. For the application of CaO treatment under field conditions, further study is required to examine dechlorination under dynamic conditions. 98

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Table 4-1. Calcium oxide, water, and soil (20 g dry weight) used for this experiment CaO (g) D.I. Water (g) Water content () Mole ratio CaO to H 2 O 1.6 1 5 0.5 3.1 1 5 1.0 4.7 1 5 1.5 3.1 2 10 0.5 6.2 2 10 1.0 9.3 2 10 1.5 Table 4-2. Maximum temperatures measured in CaO-treated soils with different CaO/H 2 O ratios Composition (mmol) Max. Temp. ( o C) Water content () (%) Mole ratio CaO to H 2 O H 2 O CaO Ca(OH) 2 coarse sand loamy sand 5 0.5 29 0 29 54 38 5 1.0 0 0 55 74 55 5 1.5 0 29 55 111 76 10 0.5 56 0 55 69 56 10 1.0 0 0 111 153 125 10 1.5 0 56 111 184 174 The moles of Ca(OH) 2 were calculated assuming a complete conversion of CaO with equivalent moles of water. 99

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temperature (oC) 050100150200 vapor pressure (kPa) 050100150200250300350 PCE TCE cis-DCE Figure 4-1. Vapor pressures of cis-DCE, TCE, and PCE at different temperatures. The values were obtained from the CRC Handbook (Lide, 1996; 2005). particle diameter (mm) 0.0010.010.1110 pecent finer 020406080100 coarse sand loamy sand Figure 4-2. Particle size distribution curves of coarse sand and loamy sand used. 100

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time (min) 0.1110100 temperature (oC) 050100150200 0.5 1.0 1.5 A time (min) 0.1110100 temperature (oC) 050100150200 0.5 1.0 1.5 B Figure 4-3. Change of temperature in soils treated with the different mole ratios of CaO to H 2 O. A) and B) are 5 % coarse sand and loamy sand. C) and D) are 10 % coarse sand and loamy sand. 101

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time (min) 0.1110100 temperature (oC) 050100150200 0.5 1.0 1.5 C time (min) 0.1110100 temperature (oC) 050100150200 0.5 1.0 1.5 D Figure 4-3. Continued. 102

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mole ratio (CaO/H2O) 0.00.51.01.52.0 chloride (mmol) 0.00.20.40.60.81.01.2 cis-DCE TCE PCE A mole ratio (CaO/H2O) 0.00.51.01.52.0 chloride (mmol) 0.00.20.40.60.81.01.2 cis-DCE TCE PCE B Figure 4-4. Levels of chloride in CaO-added soils with the different CaO/H 2 O ratios. A) 5 % coarse sand, B) 5 % loamy sand, C) 10 % coarse sand, and D) 10 % loamy sand. 103

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mole ratio (CaO/H2O) 0.00.51.01.52.0 chloride (mmol) 0.00.20.40.60.81.01.2 cis-DCE TCE PCE C mole ratio (CaO/H2O) 0.00.51.01.52.0 chloride (mmol) 0.00.20.40.60.81.01.2 cis-DCE TCE PCE D Figure 4-4. Continued. 104

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temperature (oC) 20406080100120140160180200 Cl/Ca ratio (mmol/mmol) 10-610-510-410-310-210-1 coarse sand loamy sand ABC temperature (oC) 20406080100120140160180200 Cl/Ca ratio (mmol/mmol) 10-610-510-410-310-210-1 coarse sand loamy sand ABC A temperature (oC) 20406080100120140160180200 Cl/Ca ratio (mmol/mmol) 10-610-510-410-310-210-1 coarse sand loamy sand ABC temperature (oC) 20406080100120140160180200 Cl/Ca ratio (mmol/mmol) 10-610-510-410-310-210-1 coarse sand loamy sand ABC B Figure 4-5. Ratio of Cl to Ca and the maximum temperatures achieved with different CaO/H 2 O ratios. A) cis-DCE-contaminated soils and B) TCE-contaminated soils. 105

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CHAPTER 5 THE REMOVAL OF TRICHLOROETHYLENE FROM SOIL USING THE HYDRATION OF CALCIUM OXIDE 5.1 Introduction The previous chapters discussed chemical reactions during the hydration of CaO with chloroethylenes in water and wet soil. Chapter 4 discussed the dechlorination of chlorinated ethylenes in soil by the addition of CaO and revealed the impact of soil moisture and soil composition on the reaction. The experiments conducted in the previous chapters were batch tests in a closed system to minimize loss of chemicals. The batch test in a closed system is useful for examining the differences before and after CaO treatment, but it does not allow us to investigate a dynamic condition during the hydration of CaO with a volatile chemical. To understand the mechanisms of TCE removal in a dynamic condition in soil caused by CaO addition, an open system was introduced in this study to allow TCE to escape from the system. The study focused on products released by adding CaO to soil. Volatilization of an organic contaminant in unsaturated soil is one of the main mechanisms for transporting the contaminant into the environment. When an organic compound is spilled onto soil, part of the compound will be sorbed on the surface of the soil, another part of the compound will be dissolved in water in the soil, some part of the compound will be vaporized in air in the soil, and the remainder of the compound will escape to the atmosphere. The properties of the chemical, soil, and the environment affect the distribution. Influential soil properties are organic content, pH, water content, surface area, and other factors. The chemical properties affecting the distribution include vapor pressure, solubility, functional groups, and sorption characteristics. Environmental conditions influencing the distribution include temperature, humidity, and wind speed (Guezni and Beard, 1974). When a contaminated soil is remediated, 106

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especially when the soil contains volatile organic compounds (VOCs), these influencing parameters are engineered to separate the contaminant from the soil. In the influential parameters, the desired temperature and water content of soil may be achieved by adding moisture and applying calcium oxide (CaO) because the reaction of CaO with water is an exothermic reaction and consumes water. Quicklime, mainly composed of CaO, is frequently applied to facilitate construction projects by amending the physical and chemical properties of soil (NLA, 2004). Depending on the CaO content in quicklime, the heat liberated by the hydration of the quicklime ranges from 880 to 1,140 kJ/kg (380~ 490 Btu/lb) (Boyton, 1980). The individual impact of temperature or water content cannot be evaluated separately during CaO treatment since the two parameters are interrelated. The synergetic impact of CaO treatment, however, may be estimated by using the removal efficiency of a contaminant integrally. Matsumoto et al. (1995) documented that up to 99.9 % of the TCE in soil was removed by mixing quicklime by shovel with the soil at 1 %~ 4 % by weight every 5 hours for 20 hours. However, a low concentration of TCE (16 mg/kg) was used for their experiment and the detailed gas-phase compounds that were formed by the treatment were not examined. CaO treatment on a contaminated soil may cause the destruction of the contaminant, especially chlorinated ethylenes, as discussed in Chapters 2 and 3. The fate of chlorinated ethylenes varies with the mole ratio of CaO to H 2 O, the presence of air, and the type of chemicals. When treated with CaO in a soil environment, TCE may undergo volatilization as well as destruction. Under the exothermic reaction between CaO and water, TCE can be removed by being volatilized or decomposed. However, major parameters governing TCE removal using CaO treatment are rarely reported. In this research, volatile removal of TCE in soil was measured 107

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with a 0 %, a 5 %, a 10 %, and a 20 % CaO dose. The amounts of TCE volatilized by CaO addition in different soils were compared to those in the soils without CaO addition. In addition, volatilized organic byproducts by CaO addition were measured. 5.2 Influential Parameters Potentially Caused by CaO treatment 5.2.1 Temperature The change of vapor pressure of a compound at different temperatures affects the concentration of the compound in the gas phase and its evaporation rate (Schwarzenbach et al., 2002). An increase in temperature usually increases the vapor pressure (Eq. 5-1). Thermodynamically, the Clausius-Clapeyron equation describes the relationship between temperature and vapor pressure of a pure liquid at phase equilibrium (Atkins, 1998). If enthalpy of vaporization of a chemical is constant, vapor pressure of the compound changes in a log scale by changing temperature. Assuming the ideal-gas behavior of a compound and ignoring the amount of the sorbed compound on soil particles, and using the vapor pressure at a given temperature, the concentration of the compound in the gas phase in soil can be predicted using Eq. 5-2. 2)(ln RT THdTpdvap [5-1] p : vapor pressure Hvap : the enthalpy of vaporization T : temperature (K) R : gas constant RTpVnCggg [5-2] gC : gas phase concentration of the compound gn : mole of the compound in gas phase gV : volume of the gas 108

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5.2.2 Water content Volatilization of a compound from soil is also affected by water content in the soil, if the compound is weakly polar or non-polar, because the compound competes with water for adsorption sites on the soil particles (Guenzi and Beard, 1974). Under low-water-content conditions (roughly less than 5 %), there is generally an inverse relationship between the amount of the compound adsorbed in the soil particles and the water content. Ong and Lion (1991) explained the mechanisms for TCE vapor sorption onto soil minerals in regard to water content. They found that the amount of TCE vapor on oven-dried soils was several orders of magnitude greater than that on wet soils. Since water vapor has a stronger affinity to the polar soil surface than the TCE vapor, an increase in water content reduces the sorption sites for the TCE vapor and causes it to volatilize (Ong and Lion, 1991). However, the water increased additionally in the pore space of the soil may result in reducing the movement of TCE vapor by blocking the pathway for gas phase diffusion. The effective diffusion coefficient of a chemical through the air space in soil is four orders of magnitude greater than through water in soil (Grifoll and Cohen, 1994). 5.3 Methods and Materials 5.3.1 Reagents Trichloroethylene (Alfa Aesar, 99.5 %) was used to synthesize soils. Calcium oxide (Fisher Scientific, certified grade) was used to treat the synthesized soils. Methanol (Fisher Scientific, GC resolv) was used to trap and extract the products. The external standard used was 1,2-dichloroethylene (Acros Organics, 99 %). 5.3.2 Soils Soils used were collected from three soil master horizons (A and E mixed horizon [AE], E1 horizon [E], and Bt horizon [B]) at a University of Florida Research Center (Pine Acres soil 109

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pit in Citra, Florida). All soils were dried in an oven at 105 o C for 12 hours. Large particles and plant matter of the soils were removed using a # 40 sieve. The particle size distribution and the physical and chemical properties of the sieved soil are shown in Figure 5-1 and Table 5-1. 5.3.3 Synthesis a TCE-contaminated Soils and CaO Addition The test vessels used in Chapter 2 and Chapter 3 (Appendix A) were used to synthesize a contaminated soil and treat it with CaO. To synthesize the TCE-contaminated soil, a known volume of water was added to a test vessel that already contained weighed CaO in the cavity of the Teflon plunger. TCE (100 uL) was then added to the water with a needle syringe through a sampling port on the side. The water and TCE were mixed by shaking and dry soil (50 g) was immediately added through a side port. The soil was distributed evenly across the bottom of the vessel by tapping the vessel. The contaminated soil synthesized remained sealed at room temperature for 12 hours before being treated with the CaO in the cavity of the plunger. The degree of saturation of the soils was adjusted to approximately 50 % with a15 % gravimetric water content ( ) in AE soil and E soil and a 20 % in B soil, respectively. CaO treatment was conducted by threading the Teflon plunger containing CaO down into the vessel and emptying it on the soil synthesized. The CaO was mixed with the soil by shaking and tapping the vessel vigorously. Three amounts of CaO (2.5 g, 5 g and 10 g) were used to treat the soils. Blank tests with TCE-contaminated soils but without adding CaO were also conducted. The weight percent of CaO over dry soil was used to express the results as a 0 % (blank), a 5 %, a 10 %, and a 20 % CaO dose. During the CaO treatment, nitrogen gas (20 mL/min) was flushed through the headspace of the vessel to collect TCE volatilized and byproducts within methanol traps (Figure 5-2). The methanol traps were replaced on a scheduled basis as shown in Table 5-2. Soil/vessel temperature was measured by attaching a thermocouple to the wall of the vessel and recoded 110

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using QuadTemp data logger (Fisher Scientific, Sewanee, GA, USA) (Figure 5-2). After 3 hours of treatment, a known volume of methanol was injected into the vessel with a 100 mL syringe by connecting it to a valve of a side sampling port. The vessel containing the methanol was mixed in a rotator for 12 hours to extract TCE from the treated soil. 5.3.4 Estimation of Initial TCE in Headspace, Water Content, Percent Recovery, and Cumulative TCE Removal 5.3.4.1 Initial TCE in headspace Since an appropriate headspace volume of the vessel is required to mix the CaO and wet soil, a part of TCE added in a soil synthesized will partition into the headspace. To estimate the initial concentration of TCE in a soil, the initial TCE mass in the headspace was calculated using Eq. 5-3 and Eq. 5-4. It was assumed that the TCE diffusion from soil to the headspace for the first few minutes was insignificant without the addition of CaO and that the TCE removal was simply because of dilution of the vessel headspace by the volume of nitrogen flushed. utVVnntHitH000,, [5-3] 0,tHn and = the moles of TCE in headspace of the vessel at time = 0 and time = i. itHn, 0V = the volume of headspace (77 mL). u =the flow rate of nitrogen gas being flushed into the vessel (20 mL/min). t = time. The moles of TCE() that is removed from the headspace by flushing between t = 0 and t = i is equal to the difference between the initial moles of TCE () in the headspace and the TCE remaining () at time t. The initial moles of TCE in the headspace can be calculated by Eq. 5-2. itRn, 0,tHn itHn, itHtHitRnnn,0,, 111

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itRn, is the moles of TCE removed at t=i. utVVnnitRtH00,0,1 [5-4] 5.3.4.2 Estimating water content in CaO-treated materials The amount of water changes after CaO treatment because of the hydration of CaO and the loss of water vapor during flushing with nitrogen gas. The water content ( ) of a material treated was calculated indirectly using the amount of water consumed by CaO and the difference between the initial and final weight of the vessel with Eq. 5-5. The removed mass of TCE was not included since the amount was negligible. 100)]([)(18(%),,,, fvivwCaOsoilfvivCaOwMMMMMMMnM if [5-5] CaOOHnn2 wM , and are the mass of water, soil, and CaO added to a vessel. soilM CaOM CaOn and are added moles of CaO and water OHn2 ivM, and are the initial and the final weight of the vessel containing the material treated. fvM, 5.3.4.3 Percent Recovery and cumulative TCE removal Percent recovery of TCE was calculated as the ratio of the sum of TCE collected in traps and TCE extracted from a test vessel to the TCE spiked initially. The relative percentage of cumulative TCE removed from the CaO-treated soil (referred to as cumulative TCE removal below) was calculated by dividing the cumulative removed TCE at t = i by the sum of the total TCE collected in the methanol traps and TCE extracted from the material treated at the end of the treatment (the residual TCE in the material treated) (Eq. 5-5). 100(%)180,180,,tStRitRitnnnR at t = i [5-6] 112

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(%)itR : cumulative TCE removal itRn, : the sum of moles of TCE removed at time i 180,tRn : the sum of moles of TCE removed from the beginning to the end of an experiment (t = 180 minutes) 180,tSn : the moles of residual TCE in the material treated 5.3.5 Chemical Analysis Chemicals collected in the extracts and traps were analyzed by gas chromatograph/mass spectrometry (GC/MS, Finnigan Trace 2000) and gas chromatograph/flame ionization detection (GC/FID, Hewlett Packard 5890 Series II). Dichloroacetylene (DCA) was not quantified directly since a commercial standard for DCA was not available. Greim et al. (1984) used 1,2-dichloroethylene with an analogous structure and estimated that the error might not exceed more than 50 %. DCA was quantified using 1,2-dichloroethylene in this study. 5.4 Results and Discussion 5.4.1 Temperature Dynamics The maximum temperatures of the soil/vessel during the hydration of CaO reached 38 o C, 55 o C, and 80 o C with a 5 %, a 10 %, and a 20 % CaO dose, respectively. Figure 5-4 shows typical temperature profiles of the soil/vessel with 50g of B soil being mixed with a 5 %, a 10 %, or a 20 % CaO. The temperatures increased rapidly in the beginning of the treatment and peaked within 20 minutes of mixing CaO with the soil. The temperature of the soil/vessel without adding CaO (a 0 % CaO dose) remained at room temperature (23 2 o C). Assuming phase equilibrium at an equilibrium temperature, the potential TCE mass in the headspace and air in the soil was calculated using Eq. 5-2. With TCE vapor pressures of 74 mmHg at 25 o C, 214.5 mmHg at 50 o C, and 519.8 mmHg at 75 o C (Lide, 1998), TCE masses calculated in the gas phase of the vessel were 0.35mmol at 25 o C, 0.94 mmol at 50 o C a and 2.1 mmol at 75 o C. These values were equivalent to 32 %, 84 %, and 190 % of TCE spiked into the 113

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vessel initially. Since TCE spiked to a synthesized soil was 1.1 mmol, a potential mass in the headspace was not able to exceed 1.1 mmol. Therefore, at the maximum temperature achieved during CaO treatment with 20 % CaO, the gas phase of headspace is able to contain almost twice as much as the amount of TCE spiked. Therefore, if a TCE-contaminated soil contains the amount of TCE more than that of TCE used for this experiment, the difference in the potential TCE masses in the headspace when treated with a 20 % CaO dose may be larger than that calculated in this experiment. The change in temperature measured on the exterior of the test vessel may not be completely representative of the changes in soil temperature because a portion of the heat generated is being consumed to heat the test vessel’s materials – glass (165 g) and Teflon (255 g). However, these simple calculations may be useful for predicting and interpreting the impact of CaO treatment on a chemical in a soil. 5.4.2 TCE Removal from Three Soils with Different CaO Doses Figure 5-2 shows the mass of TCE extracted by methanol from materials treated for 3 hours with a 0 %, a 5 %, a 10 %, and a 20 % CaO dose. The mass of TCE remaining in the test vessel decreased with an increasing CaO dose, but the differences among the masses of residual TCE in CaO-treated materials were not significant except in the B soil treated with a 5 % CaO dose. The initial TCE concentration in the headspace of a test vessel was calculated using the average amount of TCE removed by flushing without adding CaO in the first 5 minutes (using Eq. 5-4). The average amount of TCE removed during the first 5 minutes of flushing without CaO treatment was 0.21 0.03 mmol (n = 9) and that was equal to 19 3 % of the TCE spiked. The calculated was 0.37 mmol with = 0.21 mmol, = 77.3 mL (the headspace of 0,tHm 5,tRm 0V 114

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a test vessel containing 50g soil), = 20 mL/min, and t = 5 min. This value estimated indicated that the initial TCE mass in soil was 66 % of the spiked TCE. The estimated initial TCE concentrations of soils were 1700 mg/kg (wet weight) in both AE soil and E soil and 1630 mg/kg (wet weight) in B soil. u To estimate final concentrations of TCE in materials treated and the TCE removal efficiencies with different CaO doses, the total mass of the materials treated was estimated using water content calculated in the materials treated, soil, and Ca(OH) 2 . With a 5 %, a 10 %, and a 20 % CaO dose, the loss of moisture escaped ranged from 1 % to 3 % of the initial . The final water contents estimated using Eq. 5-5 were 14.4 %, 12.8 %, and 9.6 % in B soil treated with a 5 %, a 10 %, and a 20 % CaO dose, respectively. The final water contents were 10.9 %, 9.3 %, and 6.2 % in AE and E soil treated. Using an average residual TCE mass of the soils treated and the total mass of the materials with the estimated water contents, TCE concentrations were calculated as shown in Table 5-3. Based on the initial concentrations of TCE in soils and the final concentrations in the soils treated, the TCE removal efficiencies (%) with different CaO doses in different soils are shown in Table 5-4. The results indicated that approximately 98 % 99 % TCE was removed from the soil by the 5 % 20 % CaO addition except TCE in B soil with 5 % CaO. Spontaneous removal in AE soil without CaO addition was reached at 56 %, but did not exceed more than 20 % in E and B soil. 5.4.3 TCE Volatilization by CaO Addition Figure 5-5 shows cumulative TCE removals in three soils treated with a 0 %, a 5 %, a 10 %, and a 20 % CaO dose. The dashed line and dotted line indicate 90 % and 95 % cumulative TCE removal, respectively. In AE soil, the percents of TCE recovered with a 0 %, a 5 %, a 10 %, and a 20 % CaO dose were 90 5 % (n = 3), 92.5 3 % (n = 3), 88 2 % (n = 2), and 89 1 % 115

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(n = 2) of the TCE spiked, respectively. Spontaneous cumulative TCE removal in AE soil was 67 8 % in 3 hours. However, cumulative TCE removal in AE soil after 60 minutes without CaO addition was significantly slowed down. The cumulative TCE removal between 60 to 180 minutes was around 5 %. Comparing cumulative TCE removals with time in AE soil treated with different CaO doses, approximately 20 to 25 minutes were required to reach 90 % and 95 % cumulative TCE removal with a 20 % and a 10 % CaO dose but 55 to 80 minutes with a 5 % CaO dose (Figure 5-5 A). The times required for the 90 % or 95 % TCE removal with a 10 % and a 20 % CaO dose did not vary, but that with a 5 % CaO dose was approximately three times as long as those with a 10 % and 20 %. The percents of the recovered TCE in E soil treated with a 0 %, a 5 %, a 10 %, and a 20 % CaO dose were 88 3 % (n = 3), 95 2 % (n = 2), 87 12 % (n = 4), and 77 7 % (n = 4), respectively. In E soil, the 90 % and 95 % cumulative TCE removals with a 10 % and a 20 % CaO dose were achieved in a similar time, 20-35 minutes (Figure 5-5 B), as with that in the AE soil. In E soil, 90 % cumulative TCE removal by adding a 5 % CaO was as fast as with a 10 % and a 20 % dose. The 95 % cumulative TCE removal with a 5 % CaO dose was achieved around 75 minutes after mixing. In spite of the similarity of particle size distribution between AE and E soils, the difference in times required for a cumulative TCE removal with a 5 % CaO dose may be caused by the difference in organic content of the two soils. Organic matter in AE soil likely delayed TCE removal by holding TCE on the surface. In B soil, the percents of the recovered TCE with a 0 %, a 5 %, a 10 %, and a 20 % CaO dose were 95 1 % (n=3), 92 3 % (n=3), 95 5 % (n=3), and 90 8 % (n=3), respectively. With a 20 % and a 10 % CaO dose, it took less than 20 and 40 minutes, respectively, to achieve 95 % cumulative TCE removal from B soil (Figure 5-5 C). However, with a 5 % CaO dose, the 116

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cumulative TCE removal increased slower in B soil than that in the other soils. The cumulative TCE removed at the end of the treatment was 78 10 %. Comparing the cumulative TCE removals in B soil (sandy loam) to those in E soil (sand), the high clay content in B soil did not significantly affect the TCE volatilization with both a 10 % and a 20 % CaO dose. However, with a 5 % CaO dose, the difference of the cumulative TCE removal in B soil and in E soil was distinguishable. It implied that a 10 % and a 20 % CaO dose generated enough heat to overcome the obstacles retarding the TCE volatilization such as high organic content (AE soil) and high content of clay (B soil). However, further removing TCE in the soils may be achieved by extending time for the treatment since TCE was continuously but slowly released from the soils treated at the end of the experiments’ measurement period. Comparing the results of cumulative TCE removal in the three soils to temperature rises by CaO addition, considerable TCE removal occurred within 40 minutes after CaO addition. The temperature increase in the treated materials could create the different TCE concentrations between the headspace of a vessel and in the air space of the treated materials. The gradient of the concentration might create a driving force to transport TCE from the soil treated to the headspace of the vessel. Also, when CaO consumes water in the soil, void space increased in the soil treated should help the TCE migration through the soil. The changes in temperature and air space in the treated materials may result in considerable TCE removal in the beginning of the treatment. 5.4.4 Formation of Dichloroacetylene from TCE-contaminated Soil during CaO Treatment As discussed in the preceding chapter, dichloroacetylene (DCA) is a primary organic product of the reaction of TCE with Ca(OH) 2 . The amount of DCA and TCE collected in traps during CaO treatment is presented in Figure 5-6. The formation of DCA was confirmed in all 117

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soils treated with a 20 % CaO dose, but DCA was found in only one E soil sample among the triplicate samples with a 10 % dose. The plotted values of DCA and TCE are the total DCA and total TCE collected in a set of scheduled traps. DCA peaks occurred at 5 to 10 minutes after the TCE peaks, perhaps because the initial TCE in the headspace was flushed at the beginning of the experiments. In addition, TCE volatilized from the soil in the beginning of the treatment did not have sufficient contact time with Ca(OH) 2 since Ca(OH) 2 might not be sufficiently formed. DCA formation may be increased when TCE in the soil moves through Ca(OH) 2 formed in the soil at elevated temperatures. The formation of DCA decreased over time with the decrease of TCE in the soils treated. Comparing the formation of DCA in different soils, the largest quantity of DCA was produced in E soil. The quantity of DCA in E soil treated with a 20 % CaO dose was two to three times greater than that observed in AE soil and B soil. The DCA formed in E soil treated with a 10 % CaO dose was only 1.4 % of that in E soil with a 20 % CaO. The prominent formation of DCA in E soil with a 20 % CaO may be caused by the more favorable conditions for vigorous hydration of CaO than in the other soils, such as an even distribution of water and better mixing of CaO in the coarse-grained soil. Assuming that 1 mole of TCE can produce 1 mole of DCA, the estimated amount of DCA formed ranged from 2 % to 5 % of the TCE spiked initially. 5.4.5 Implications and Limitations The enhanced volatilization of TCE from soil by adding CaO revealed that CaO treatment was a feasible remediation technique to remove a volatile compound from the soil. Since the removal of TCE was affected by soil properties such as the organic content and clay content, the TCE removal efficiency varied with soil types and the quantity of a CaO dose. Increasing a CaO dose to a TCE-contaminated soil increased TCE removal in the soil. However, a high CaO dose resulted in the formation of DCA. The optimum CaO dose for TCE removal was discovered 118

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using a simple experiment using the test vessel. Reducing the formation of DCA and minimizing the amount of CaO addition, the optimum performance of TCE removal by CaO addition in a 3-hour treatment was obtained with a range of 5 %-10 % CaO doses in sand (AE soil. 0.55 % OC, 1.2 % clay), a 5 % CaO dose in sand (E soil, 0.13 % OC, 1.9 % clay), and a 10 % CaO dose in loamy sand (B soil, 0.06 % OC, 19.2 % clay). TCE removal with CaO addition may vary with the concentration of TCE in soil. The estimated TCE concentration in synthesized soil was from 1630mg/kg to 1700 mg/kg for this study. In this range, most TCE is present in the condensed phase (liquid phase) in the soil. However, if the TCE concentration in the soil is low, most TCE are present in the dissolved phase of water in the soil and in the gas phase of the void of the soil. For example, the maximum TCE concentration of excavated soil in the Fairbanks disposal pit (FDOT, 2002) was 85 mg/kg. In this scenario, TCE removal can be achieved easily with CaO addition. If added CaO consumes water in the soil, TCE dissolved in the water is likely to be vaporized rather than being concentrated in the remaining water. TCE in the remaining water with elevated temperature is also likely to be vaporized. Consequently, TCE is likely to be removed by a smaller amount of CaO addition in the soil with a low concentration of TCE. Air-water partitioning of a chemical is commonly explained by Henry’s law. Heron, et al. (1998) reported that TCE volatilization in water was significantly increased by increasing temperature. In Heron et al.’s measurement, the Henry’s law constant for TCE increased by a factor of 20 between 10 o C and 95 o C. However, the experiment in this study has limitations in predicting the results of large-scale field application. The TCE within the test vessel was close to at phase equilibrium before the CaO treatment, and this may not occur under field conditions. The large difference between TCE levels in the soil and the ambient air in the field may supply a greater driving force for TCE 119

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transportation. To apply and predict TCE removal with CaO treatment (quicklime) under a large-scale field conditions (in case of exposed to ambient air), other parameters should be considered such as ambient conditions, soil properties, other contaminants, the method of mixing, and other field conditions listed below: Ambient temperature Wind speed Other degree of saturation in soil by water Quality of quicklime (CaO content) Degree of quicklime mixing (homogeneous mixing) The ratio of the surface of the CaO-treated material exposed to the ambient The depth of treated material. 5.5 Summary and Conclusions The volatilization and destruction of TCE during and after CaO application were measured in two sands and loamy sand. The results are summarized below. The maximum temperatures of the soil/vessel during the hydration of CaO in soil were 38 o C, 55 o C, and 80 o C with a 5 %, a 10 %, and a 20 % CaO dose, respectively. Assuming that TCE was at phase equilibrium with the maximum temperatures, it was estimated that most TCE spiked was vaporized in the maximum temperature by adding a 10 % and a 20 % CaO dose. However, actual temperature in the treated soil was likely to be higher than the temperature measured on the exterior of the test vessel since a large portion of the heat generated was consumed by the test vessel’s materials. The total mass of TCE remaining in the vessel decreased with an increase in a CaO dose but the differences among the residual TCE masses were not significant except in loamy sand (B soil) treated with a 5 % CaO dose. CaO treatment of two sands (AE and E soil) for 3 hours 120

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resulted in 97 %-99 % TCE removal based on the estimated initial TCE concentration with 5 %-a 20 % CaO doses in sands. TCE removal in sandy loam (B soil) ranged from 79 % to 99 % with 5 %-20 % doses. The volatile removal of TCE in different soils varied with the amount of a CaO dose and the length of treatment. Increasing the amount of a CaO dose in all soils reduced the required time for 95 % cumulative TCE removal. However, the required time with a 10 % and a 20 % CaO dose was close to each other. With a 5 % CaO dose, it took 55 minutes and 35 minutes to achieve 90 % cumulative TCE removal from AE soil and E soil, respectively, while in B soil with a 5 % CaO dose, 90 % cumulative TCE removal was not observed within 3 hours. The results revealed that generating more heat with a higher CaO dose overcame the obstacles retarding the TCE volatilization such as high organic content and high clay content that might happened with a low CaO dose. The formation of DCA was observed only with a 20 % CaO dose in all soils but in only one of three E soil samples with a 10 % dose. The largest quantity of DCA was produced in E soil with a 20 % CaO dose. The prominent formation of DCA in E soil with a 20 % CaO was likely to occur because of favorable conditions for the vigorous hydration of CaO with better mixing CaO in coarse grain size. The estimated amount of TCE that converted to DCA did not exceed 5 % of the TCE spiked initially. Enhanced volatilization of TCE from soil by adding CaO revealed that volatilization was the primary mechanism of TCE removal in soil. Considering the time period of the CaO treatment, the formation of DCA, and TCE removal, the optimum CaO dose ranged from 5 %-10 % CaO doses in sand (AE soil. 0.55 % OC, 1.2 % clay), a 5 % CaO dose in sand (E soil, 0.13 % OC, 1.9 % clay), and a 10 % CaO dose in loamy sand (B soil, 0.06 % OC, 19.2 % clay). 121

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However, the experiment in this study has limitations in predicting the results of large-scale field applications. To apply and predict TCE removal with CaO treatment (quicklime) under a large-scale field conditions, other parameters such as ambient conditions, soil properties, other contaminants, the method of mixing, and other field conditions should be considered. When CaO (quicklime) is added to a soil contaminated with multiple contaminants, such as heavy metals, the impact of CaO treatment on the contaminants must be considered as well. If a soil is contaminated with VOCs and heavy metals, the modified soil environment by CaO application, such as high pH, may have an influence on the leachability of heavy metals and on other pH-sensitive chemicals from the soil treated. In addition, extensive study is required to apply CaO on soils with other VOCs because of the variable volatilities of the chemicals. Other concerns with CaO application include the impacts of the treatment on soil environment and the disposal of the treated materials. 122

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Table 5-1. Physical and chemical properties of soils used in this study Parameter AE soil E soil B soil Bulk density (gm/cm 3 ) 1.46 1.56 1.26 % OC 0.55 0.13 0.06 Porosity 0.45 0.41 0.52 Particle size distribution % sand 95.2 95.1 76.5 % silt 3.6 3.0 4.3 % clay 1.2 1.9 19.2 Classification According to USDA Texture Diagram sand sand sandy loam organic content Table 5-2. Experimental parameters used for synthesizing contaminated soil and for CaOtreatment with a test vessel Parameter Flow rate 20 1mL/min Soil 50 g (AE soil, E soil, and B soil) Water 7.5 mL for AE soil and E soil, 10mL for B soil Calcium oxide 0 g, 2.5 g, 5 g, and 10 g Trichloroethylene 100 uL (1.1 mmol) Time schedule for traps 5, 10, 15, 20, 25, 30, 40, 50, 60, 75, 95, 120, 150, and 180 minutes 123

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Table 5-3. Concentration of TCE calculated in the treated material with a 0 %, a 5 %, a 10 %, and a 20 % CaO dose. CaO Dose Soil 0 % 5 % 10 % 20 % AE 746.1 27.2 32.7 15.1 E 1393.0 40.9 26.1 16.6 B 1338.3 335.6 28.6 20.6 Unit is milligram (mg/kg (wet weight)). Table 5-4. The removal efficiencies of TCE in the soils treated with a 0 %, a 5 %, a 10 %, and a 20 % CaO dose. CaO Dose Soil 0 % 5 % 10 % 20 % AE 56.1 98.4 98.1 99.1 E 18.0 97.6 98.5 99.0 B 17.8 79.4 98.2 98.7 Unit is %. Percent removal (%) = 100[1-(a concentration of TCE in treated material/the estimated initial TCE concentration of a soil)] 124

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Grain size (mm) 0.0010.010.1110 Percent finer (%) 020406080100 AE E B Figure 5-1. The particle size distribution of used soils (AE, E, and B). 125

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45o N2flowtwo way valve thermometer ventmethanol traps insulation N2flow N2Gasregulatormethanol trapsthree way valve 45o N2flowtwo way valve thermometer ventmethanol traps insulation N2flow N2Gasregulatormethanol trapsthree way valve Figure 5-2. Collection of volatilized products in the methanol traps after adding CaO to a synthesized TCE-contaminant soil. 126

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time (minute) 020406080100120140160180200 temperature (oC) 2030405060708090 20% 10% 5% Figure 5-3. Examples of the change in temperature of the test vessel during slaking with 50 g B soil and a 5 %, a 10 %, or a 20 % CaO dose. Temperatures were recorded using a data logger for 3 hours. Error bars indicate the standard deviation in three replicates. AE soilE soilB soil TCE in soil (mg) 0.1110100 0% 5% 10% 20% Figure 5-4. Mass of residual TCE in the materials treated with a 0 %, a 5 %, a 10 %, and a 20 % CaO dose. Error bars indicate the standard deviation in three replicates. 127

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time (minute) 020406080100120140160180 0102030405060708090100 0% 5% 10% 20% Rt=i (%) A time (minute) 020406080100120140160180 0102030405060708090100 0% 5% 10% 20% Rt=i (%) B Figure 5-5. Cumulative TCE removals (%) in soils treated with a 0 %, a 5 %, a 10 %, and a 20 % CaO Dose. A) AE soil, B) E soil, and C) B soil. Error bars indicate standard deviation in three samples. 128

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time (minute) 020406080100120140160180 0102030405060708090100 0% 5% 10% 20% Rt=i (%) C Figure 5-5. Continued. 129

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time (minute) 020406080100120140160180 DCA (mmol) 0.000.010.020.030.040.05 TCE (mmol) 0.00.10.20.30.40.5 DCA TCE A time (minute) 020406080100120140160180 DCA (mmol) 0.000.010.020.030.040.05 TCE (mmol) 0.00.10.20.30.40.50.6 DCA TCE B Figure 5-6. DCA and TCE removed during CaO treatment with a 20 % CaO dose in different soils: A) AE soil, B) E soil, and C) B soil. Error bars indicate standard deviation in three samples. 130

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time (minute) 020406080100120140160180 DCA (mmol) 0.000.010.020.030.040.05 TCE (mmol) 0.00.10.20.30.40.50.6 DCA TCE C Figure 5-6. Continued. 131

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CHAPTER 6 THE LEACHABILITY OF TRICHLOROETHYLENE FROM SIMULATED SOILS OF CALCIUM OXIDE-TREATMENT 6.1 Introduction Stabilization and solidification of contaminated soils have been methods used to immobilize contaminants by converting them into less soluble, mobile, or toxic forms. The use of quicklime for the immobilization of inorganic contaminated soils and solids has been studied (Dermatas and Meng 1996 and 2003; Marion et al., 1997). Dermatas and Meng (1996) stated that the leachability of some heavy metals (lead, chromium, arsenic and mercury) was significantly reduced by a quicklime-based treatment. The solubility of heavy metals varies with the pH of the solution. An increase of pH by adding quicklime can cause some heavy metals to form insoluble salts. The Pozzolanic reaction, a reaction of Ca(OH) 2 with soil minerals, also played an important role in immobilizing heavy metals by increasing the physical strength of the soil and consequently causing physical entrapment (Dermatas and Meng, 2003). Marion et al. (1997) reported that the addition of quicklime to contaminated soils stabilized organic liquids and heavy metals. They concluded that the addition of quicklime improved the physical properties of the soils for potential reuse. Quicklime has also been used to improve physical properties of oil sludge or waste from oil spills before sending them to a landfill (Morgan et al., 1984). Although some heavy metals were immobilized by chemical as well as physical changes when quicklime was added to a soil, it is difficult to immobilize volatile organic compounds (VOCs) using stabilization or solidification. VOCs are volatilized quickly when VOCs are exposed to ambient air. When water is present in soil, water can displace VOCs sorbed on soil particles (Marco et al., 1996). Marco et al. (1996) illustrated VOC immobilization in soil using an organic binder (shredded tire particles, or rice hull ash) and an encapsulating agent (ordinary Portland cement, or sodium silicate) together. They found that the most effective combination to 132

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immobilize VOCs with the organic binders and the encapsulating agents was the use of shredded tire particles and sodium silicate. The addition of CaO to trichloroethylene-contaminated soils reduced trichloroethylene (TCE) in the soil, either by the volatilization or by dechlorination of TCE, as discussed in the previous chapters, However, the efficiency of TCE removal from a soil varied with the amount of added CaO, the presence of excess water, temperature, and soil types. Under post-CaO-treated conditions, if TCE remains in the CaO-treated soil, additional reduction of TCE may occur in the long term. The dehydrochlorination and dechlorination of TCE by dry Ca(OH) 2 was proved at room temperature ranges in Chapter 3. However, if the CaO-treated soil is wet, the presence of water can inhibit the dehydrochlorination and dechlorination of the residual TCE as discussed in Chapter 2 and Chapter 4. The hydration of CaO results in the formation of calcium hydroxide (Ca(OH) 2 ). If Ca(OH) 2 is dissolved in water in the CaO-added soil, pH of the CaO-added soil increases to over 12 (Smith, 1998). The alteration of pH in soil may affect the surface area of minerals. Jozefaciuk and Bowanko (2002) demonstrated that the surface area of several minerals increased by the dissolution of Si in minerals when the minerals were treated in alkali solution. The change of soil properties that is caused by CaO addition may affect the leachability of organic contaminants from the treated soil. The leachability of a contaminant in a treated soil is a primary concern when the treated material is used for land application because of the impact of the contaminant on groundwater quality. USEPA proposed a simple linear equilibrium soil/water partition equation and a leaching test, the synthetic precipitation leaching procedure (SPLP), for the risk assessment of groundwater (EPA, 1996). In many cases, the values of the coefficients to use for the soil/water 133

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partition equation are not available because of site-specific soil properties such as a quicklime-treated soil. The SPLP test is another option to assess the risk of land-applied soils to groundwater. The SPLP test was designed by USEPA (SW846 Method 1312) to assess the mobility of organic and inorganic contaminants in liquid and solid wastes to groundwater by simulating rainwater. Even though the accuracy, suitability, and implications of the SPLP test are still controversial, the risk assessment using the SPLP test has been widely accepted by regulatory agencies in the United States (Kosson, et. al, 2002; Townsend et al., 2006). When CaO was added directly to TCE-contaminated soil, TCE is reduced by volatilization and destruction in the short term (for few hours). If remaining TCE is present in the post-CaO-treated soil for the long term, TCE may undergo additional reactions with hydrated lime, soils, and water. In this study the change of TCE concentration in the long term (1 day and 7 days) was examined under post-CaO treatment conditions. Since the amount of residual TCE varies with different conditions of CaO treatment, simulated post-CaO-treated soils were synthesized by adding a known amount of TCE to mixtures of soils with Ca(OH) 2 . TCE-contaminated soils without mixing Ca(OH) 2 were prepared to compare the change of TCE concentrations in the soils to that of simulated post-CaO soils. Finally, the TCE leachabilites of simulated post-CaO-treated soils using the SPLP test were compared to those of TCE-contaminated soils. 6.2 Methods and Materials 6.2.1 Soils Four soils were used for these experiments. Two soils were collected from different soil master horizons (A and E mixed horizon [AE] and B horizon [B]) at a University of Florida Research Center (Pine Acres located in Citra, Florida). Another soil was collected from a soil pile excavated on a site at Fairbanks, Florida [FB], and the fourth soil was obtained at Tallahassee, FL [N]. The physical and chemical properties of the soil are summarized in Table 134

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6.1. Major minerals in sand, silt, and clay fraction of the soils are presented in Table 6.2. X-ray diffraction patterns for these soils are presented in Appendix D. All soils were crushed gently with mortar and pestle after drying them at 105 o C for 12 hours. Large particles and plant matter in a soil were removed using a # 40 sieve (0.425 mm) before the soil was used. 6.2.2 Reagents Calcium hydroxide (Fisher Scientific, certified grade) was used to create a simulated post-CaO-treat soil (SPS). Trichloroethylene (Alfa Aesar, 99.5 %) was used to synthesize contaminated soils. Methanol (Fisher Scientific, GC grade) was used to extract TCE and its organic byproducts in the tested soils. 6.2.3 Synthesis of Simulated Post-CaO-treated Soils (SPS) and TCE-contaminated Soils (TS) To create an SPS, a dry soil was mixed with a known amount of Ca(OH) 2 which was equivalent to 10 % calcium oxide (gravimetric content [CaO (g)/ Soil dry (g)x100]). Water content and TCE concentration in the soil-Ca(OH) 2 mixture were adjusted by TCE-dissolved water. The TCE-dissolved water was prepared by diluting TCE-saturated water that was synthesized by rotating a 42-mL VOA vial containing 1mL TCE and 41 ml deionized water for 24 hours. After the rotation of the VOA vials, the VOA vial remained undisturbed until the condensed phase of TCE settled down and the upper part of the solution was used for the TCE-saturated water. The TCE-saturated water was diluted by adding 2 mL TCE-saturated water to 40 mL TCE-free water in a 42mL VOA vial. The concentration of TCE in the TCE-dissolved water was analyzed by GC/FID. A simulated post-CaO-treated soil (SPS) was synthesized by adding the TCE-dissolved water and a soil-Ca(OH) 2 mixture in a glass jar (I-CHEM certified TM, Chase Scientific Glass, Inc., TX, USA). The volume of the jars was 125 mL. The amount of the added TCE-dissolved 135

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water was equivalent to 20 % gravimetric water content in the soil-Ca(OH) 2 mixture. The mixture was compacted by tapping the jar gently and filled to the top of the jar to minimize the headspace. The jar containing a SPS was capped quickly. A TCE-contaminated soil (TS) was synthesized with a soil without mixing Ca(OH) 2 by adjusting the same water content as that of an SPS. The prepared samples were stored in an incubator at 20 o C. Two sets of an SPS and a TS were prepared with the same soil and the same TCE concentration. One set was treated for 1 day and the other set was treated for 7 days. The concentration of TCE in the TCE-dissolved water, the weight of each dry soil added in a jar, and the weight of the soil-Ca(OH) 2 mixtures are presented in Table 6.3. The variation in weights of soils and soil-Ca(OH) 2 mixtures added in the jars was because of different densities of soils. 6.2.4 Synthetic Precipitation Leaching Procedure (SPLP) The SPLP tests (EPA SW846 Method 1312) were used to measure leachable TCE of SPSs and TSs. Zero headspace extraction vessels (ZHEs, Analytical Testing Corporation, USA) were used for the SPLP tests. Two samples were taken with a stainless steel spatula from a soil treated and were weighed separately before being added to a ZHE. The weight of a sample was 25g. The ZHE-added samples were capped quickly. All processes were conducted inside a walk-in cooler at 4 o C to minimize the volatilization of TCE. Deionized water (500mL) was used as an extraction fluid for SPLP test. The ZHEs containing samples were rotated in an end-over-end fashion for 18 ( 2) hours. The SPLP extract was collected in a TEDLAR bag and stored at 4 o C before chemical analysis. 6.2.5 Total Concentrations of TCE in TSs and SPSs To determine TCE concentrations in the treated TSs and SPSs, TCE in the TSs and SPSs was extracted with methanol. After a soil sample was added to ZHEs in the walk-in cooler, a part 136

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of the soil in the jar was transferred into a VOA vial containing 30 of ml methanol. The mass of the sample added to the vial was determined using the difference of weight of the vial before and after adding the sample. The vials containing samples and methanol were rotated for 12 hours to extract TCE. The methanol extracts were filtered using PTFE syringe filters (0.2-um pore size, Whatman) for the analysis with gas chromatography/mass spectrometry (GC/MS, Finnigan Trace 2000). 6.2.6 Analytical Method Filtered methanol extracts was analyzed by direct injection to GC/MS. TCE and organic byproducts were analyzed with GC/MS. The SPLP extracts were analyzed using the Purge-and-Trap method (SW-846 Method 5030B) with a sample concentrator (3100 sample concentrator, Tekmar-Dohrmann) and GC/MS. Internal standards and surrogates were added to a 5-mL SPLP extract before syringing it to the sample concentrator. The levels of TCE and the percent recoveries of TCE were determined using the internal standards and surrogates. 6.2.7 The Ratio of TCE Concentrations of a SPS to a TS To compare the relative change of TCE concentration in a SPS and a TS synthesized with the same soil, the ratio of the TCE concentration of a SPS to that of a TS was calculated using Eq. 6-1. The ratio of TCE concentration in the SPLP extracts of a SPS and that of a TS was also calculated using Eq. 6-2. (mg/kg)TS a ofion concentrat TCE(mg/kg)SPSa ofion concentratTCEsoilR [6-1] (mg/L)TS a ofextract SPLP theinionconcentratTCE(mg/L)SPS a ofextract SPLP theinionconcentratTCESPLPR [6-2] 137

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6.3 Results and Discussion 6.3.1 Observed TCE Concentration of in TSs and SPSs TCE concentrations of TSs and SPSs with 1-day and 7-day treatment at 20 o C are presented in Table 6-4. The large variation of TCE concentrations between duplicated samples might be caused by a loss of TCE during the experiment because of the high volatility of TCE. In TSs with AE, FB, and N soil, TCE concentrations with 1-day treatment did not vary from those with 7-day treatment. However, TCE concentration in the B soil decreased from 5.4 mg/kg to 0.1 mg/kg by 7-day treatment. This result suggested that a significant spontaneous escape of TCE or natural decomposition of TCE, perhaps, occurred in TCE-contaminated B soil. Comparing TCE concentrations of SPSs in 1-day treatment with those in 7-day treatment, there were no significant changes in the TCE concentrations in SPSs with FB, N, and AE soil. The results suggested that 7-day treatment of SPSs did not significantly affect the changes of TCE concentrations. However, TCE concentration of the SPS with B soil was reduced from 8.1 mg/kg to 2.9 mg/kg in 7-day treatment. The TCE reduction in the simulated post-CaO-treated B soil was thought to have the same cause as in TCE-contaminated B soil. Figure 6-2 shows the values of R soil s for all soil types used for 1-day and 7-day treatment. The values of R soil s varied with different soils and periods of the treatment. Comparing R soil s among soils used, the values of R soil s with FB, N, and AE soil were less than 1. This result suggested that simulated post-CaO-treated conditions with the soils helped to reduce the TCE concentrations. The values of R soil with B soil in 1-day and 7-day treatment were greater than 1 since the concentrations of TCE in TCE-contaminated B soil were less than those in the simulated post-CaO-treated B soil in 1-day and 7-day treatment. However, both the TCE-contaminated B soil and the simulated post-CaO-treated B soil showed the reduction of TCE by 7-day treatment. 138

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However, any byproduct by the decomposition of TCE was not detected in methanol extracts of all TSs and SPSs by GC/MS analysis (The method detection limits of the byproducts were 10 g/L of the methanol extracts.). These results suggested that the destruction of TCE in the soils treated might not influence the changes of the TCE concentrations in the SPSs and TSs. 6.3.2 Observed TCE Leaching from TSs and SPSs by the SPLP Test. Leached TCE concentrations to the SPLP extracts of TSs and SPSs are summarized in Table 6-5. TCE concentrations of the SPLP extracts varied with different soils used. TCE concentrations of the SPLP extracts ranged from 7.6 g/L to 183.2 g/L. 2000). All TCE concentrations in the SPLP extracts exceeded the regulatory level (3 g/L) in the drinking water standard of TCE by the Florida Department of Environmental Protection (FDEP). The values of R SPLP s (Figure 6-3) showed a similar trend to those of the R soil s. The R SPLP s with all types of soils with 1-day and 7-day treatment were lower than 1 except R SPLP s of B soil with 7-day treatment. Lower concentrations of TCE leached to the SPLP extracts of SPSs than those of TSs with FB, N, and AE soil were caused, perhaps because TCE concentrations in the SPSs were lower than those in TSs. With B soil, the value of R SPLP was less than 1 with 1-day treatment but greater than 1 with 7-day treatment. Figure 6-4 shows the results of the simple regression analysis with TCE concentrations in TSs and TCE concentrations leached to the SPLP extracts of the TSs (solid line), and TCE concentrations in SPSs and TCE concentrations leached to the SPLP extracts of the SPSs (dashed line). With TSs, the increase in TCE concentrations leached to the SPLP extracts of TSs was proportional to TCE concentrations of the TSs (r 2 = 0.98). With SPSs, the relationship between TCE concentrations leached to the SPLP extracts and TCE concentrations of the SPSs was not as linear as that with TSs (r 2 =0.54). If the leachability of TCE was reduced under simulated post139

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CaO treatment conditions, the slope of the fitting curve with TCE concentrations of SPSs and TCE concentrations leached to the SPLP solution should be less than that of TSs. However, the slope (slope=13.4) with SPSs did not vary from that with TSs (slope=13.8). This result suggested that TCE immobilization might not occur in SPSs. The percent of the amounts of TCE leached to the SPLP extracts from the amounts of TCE in SPSs or TSs are presented in Table 6-6. The percentages ranged from 11.4 % to 159.1 % of TCE. Great divergences in the average values were observed in simulated post-CaO-treated N soil in 1-day treatment and TCE-contaminated B soil in 7-day treatment. TCE should not be leached to a SPLP extract more than the amount of TCE of the tested soil. The percent of TCE leached from TCE-contaminated B soil in 7-day treatment was, perhaps, caused by underestimating TCE concentration in the TCE-contaminated B soil. However, the other percentage values ranged from 11.4 % to 38.0 %. The average percent of TCE leached from SPSs (both 1-day and 7-day treatment) was 35 %. If an amount of leachable TCE in a CaO-treated soil is 35 % of the amount of total TCE in the CaO-treated soil, the concentration of TCE in the CaO-treated soil has to be reduced below 0.17 mg/kg to meet the drinking water standard of TCE. 6.3.3 Implications and Limitations Notwithstanding the uncertainty of the mechanism of TCE reduction in SPSs, the results suggested that TCE reduction might occur under post-CaO-treated conditions. However, the period of treatment did not significantly affect the TCE reduction under the post-CaO-treated conditions. For the beneficial use of CaO-treated soils, the results of the SPLP tests with the CaO-treated soils may compare to the level of a contaminant in the primary drinking water standard for the risk assessment of groundwater. All TCE concentrations of the SPLP extracts of the 140

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simulated post-CaO-treated soils exceeded the TCE criteria for the primary drinking water since the level of TCE in all SPLP extracts exceeded 0.003 mg/L. In this scenario, a regulatory agency may not allow the simulated post-CaO-treated soils (or CaO-treated soils) to be applied on land where it may affect groundwater quality without further TCE removal. However, since all concentrations of TCE in SPSs used met the criteria of direct exposure in residential areas (6.4 mg/kg) or (9.4 mg/kg), the SPSs may be applied on land with appropriate protection. If the TCE level of a CaO-treated soil exceeds soil cleanup target levels (SCTLs) for direct exposure, landfilling the CaO-treated soil can be another option. To landfill the CaO-treated soil in a municipal solid waste landfill, the treated soil has to be tested for toxicity characteristics. The toxicity characteristic leaching procedure (TCLP) test is a test to assess toxicity characteristics of a waste and the procedure is similar to the SPLP except for the use of a different leaching solution. The regulatory level of TCE to pass the TCLP test is 0.5 mg/L (40 CFR). 6.4 Summary and Conclusions The fate of TCE in simulated post-CaO-treated soils (SPSs) was explored in this study. The leachability of TCE from the SPSs and TSs was investigated. Observations and findings are summarized below. TCE reduction in SPSs and TSs varied with different soils. Comparing the R soil s with different soils, TCE reductions in SPSs were greater than those in TSs with soil FB, AE, and N soil. However, TCE reduction in the TCE-contaminated B soil was greater than that in the simulated post-CaO-treated B soil. TCE concentrations in SPSs and TSs with FB, N, and AE soil did not vary with different periods of treatment. However, The TCE concentration in the simulated post-CaO-treated B soil and TCE-contaminated B soil was reduced by 7-day treatment. 141

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The amounts of leachable TCE of SPSs were less than those of TSs. Simple regression analysis with TCE concentrations of SPSs and TSs and TCE concentrations of the SPLP extracts of them revealed that no TCE immobilization in the SPSs occurred by incubating them for 7 days. The percent of TCE leached out of TCE with SPSs and TSs ranged from 11.1 % to 159.1 %. The average amount of TCE leached to the SPLP extract of SPSs was 35 % of the amount of TCE of the SPSs. For the beneficial use of the treated soil, TCE level in the treated soil has to be reduced below 0.17 mg/kg to meet the drinking water standard for TCE if the average amount of TCE leached from CaO-treated soils is 35 % of the amount of TCE in the material. 142

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Table 6-1. Physical and chemical properties of test soils. Soil name FB soil N soil AE soil B soil % OM 0.05 0.05 0.55 0.06 Particle size distribution % sand 76.2 85.2 95.2 76.5 % silt 0.9 4.3 3.6 4.3 % clay 22.9 10.5 1.2 19.2 Classification According to USDA Texture Diagram sandy clay loam loamy sand sand sandy loam Table 6-2. Major minerals found in sand, silt, and clay fraction of the soils used. Soil Fraction Sand Silt Clay FB soil quartz quartz Kaolinite N soil quartz quartz kaolinite/gibbsite AE soil quartz quartz kaolinite B soil quartz quartz kaolinite Table 6-3. Parameters used to synthesize simulated post-CaO-treated soils and TCE-contaminated soils. Soil name FB soil N Soil AE soil B soil TCE concentrations in TCE dissolved waters (mg/L) 53 ( ) 53 ( ) 132 () 68 () TCE-contaminated soils (TS, g) 189 188 200 187 Simulated post-CaO-treated soils (SPS, g) 184 204 203 192 Standard deviation in thee samples. 143

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Table 6-4. Concentrations of TCE in TSs and SPSs with 1-day and 7-day treatment (mg/kg). 1-day 7-days Soil TS SPS TS SPS FB soil 2.7 ( %) 1.0 ( %) 2.1 ( %) 1.2 ( %) N soil 3.5 ( %) 0.6 ( %) 3.0 ( %) 1.8 ( %) AE soil 12.8 ( %) 6.7 ( %) 16.8 ( %) 6.5 ( %) B soil 5.4 ( %) 8.1 ( %) 0.1( %) 2.9 ( %) The values in parenthesis indicate relative percent difference (RPD (%) = 100 [(x1-x2)/ {(x1+x2)/2}]). Table 6-5. TCE concentrations in the SPLP extracts of TSs and SPSs with 1-day and 7-day treatment (g/L). 1-day 7-day Soil TS SPS TS SPS FB soil 51.7 ( %) 19.1 ( %) 37.8 ( %) 7.9 ( %) N soil 56.5 ( %) 30.7 ( %) 43.6 ( %) 26.9 ( %) AE soil 152.3 ( %) 80.9 ( %) 183.2 ( %) 122.4 ( %) B soil 55.8 ( %) 46.4 ( %) 7.6 ( %) 36.7 ( %) The values in parenthesis indicate relative percent difference (RPD (%) = 100 [(x 1 -x 2 )/ {(x 1+ x 2 )/2}]). Table 6-6. Percents of TCE leached to the SPLP extracts of TSs and SPSs from TCE in the TSs and the SPSs treated for 1 day and 7 days (unit: %). 1-day 7-day Soil TS SPS TS SPS FB soil 37.7 38.0 36.7 12.8 N soil 32.7 98.9 28.7 30.3 AE soil 23.8 24.3 21.8 37.4 B soil 20.5 11.4 159.1 25.6 Average 28.7 43.2 61.6 26.5 144

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TCE-contaminated soil(soil, TCE-dissolved water) Simulated post-CaO-treated soil(soil, Ca(OH)2, TCE-dissolved water) Synthesis of test samples Treatment of synthesized samples( 20 oC, 1 day and 7 day) Methanol extraction GCMS analysis for byproduct and TCE SPLP test TCE-contaminated soil(soil, TCE-dissolved water) Simulated post-CaO-treated soil(soil, Ca(OH)2, TCE-dissolved water) Synthesis of test samples Treatment of synthesized samples( 20 oC, 1 day and 7 day) Methanol extraction GCMS analysis for byproduct and TCE SPLP test Figure 6-1. Schematic diagram of the experimental procedure. 145

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FBNAEB Rsoil 0.20.40.60.81.21.41.60.01.0 A FBNAEB Rsoil 0.20.40.60.81.21.429.00.01.030.0 B Figure 6-2. Ratios of TCE concentrations in simulated post-CaO-treated soils (SPSs) to those of TCE-contaminated soils (TSs) with FB, N, AE, and B soil in 1-day and 7-day treatment. A) 1-day and B) 7-day. 146

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FBNAEB RSPLP 0.10.20.30.40.60.70.80.90.00.51.0 A FBNAEB RSPLP 0.20.40.60.84.00.01.05.0 B Figure 6-3. Ratios of TCE concentrations in the SPLP extracts of simulated post-CaO-treated soils (SPSs) to those of TCE-contaminated soils (TSs) with FB, N, AE, and B in 1-day and 7-day treatment. A) 1-day and B) 7-day. 147

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TCE of SPSs and TSs (mg/kg) 024681012141618 TCE of the SPLP extracts (ug/L) 050100150200250 SPS TS Figure 6-4. Simple regression analysis with TCE concentrations of TSs and SPSs and those of the SPLP extracts. Solid line is the linear fitting curve with the results of TSs. Dashed line is the results of SPSs. 148

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CHAPTER 7 SUMMARY AND CONCLUSIONS 7.1 Summary Quicklime (calcium oxide, CaO) is frequently used to facilitate construction projects with soil by amending the physical properties of the soil, such as water content and plasticity. A reaction process known as slaking occurs when calcium oxide is hydrated. The process consumes water and generates heat. Quicklime may also be added as part of soil cleanup operations to create a more favorable physical soil condition for treatment. At a site in Fairbanks, Florida, U.S.A., quicklime was added to excavated soils to increase the workability of soil containing a large fraction of clay (FDOT, 2002). After mixing, it was found that several volatile organic pollutants were removed to levels below that required for cleanup (FDOT, 2002). The major contaminants at the Fairbanks site were highly volatile compounds, including trichloroethylene (TCE), 1,1,1-trichloroethane, 1,1-dichloroethlyene, and benzene. The unanticipated observations of the removal of volatile organic compounds (VOCs) by quicklime addition have raised questions about whether the use of quicklime to remove VOCs from soil is feasible. Three ways in which quicklime addition may affect the fate of soil contaminated with organic chemicals are (1) degradation of the chemicals, (2) volatilization of the chemicals by increased temperature, or (3) immobilization of the contaminants in the soil-Ca(OH) 2 matrix (Sedlak et al., 1991). This research was conducted to evaluate the impact of quicklime application on chlorinated ethylenes in soil. Five major experiments were conducted in this study. In the first experiment, the fate of PCE, TCE, and cis-DCE during the hydration of CaO was assessed by measuring organic byproducts and extractable chloride (i.e., inorganic byproduct) in the CaO-treated chlorinated ethylenes. The impact of the amount of water on the reaction was evaluated by conducting the 149

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experiment at two mole ratios—Ca/H 2 O: 1:1 and 1:2. The impact of the presence of air was evaluated by conducting experiments in the presence and absence of air. A mass balance was performed with the quantities of the observed byproducts. Results indicated that chlorinated ethylenes (PCE, TCE, and cis-DCE) likely reacted with the Ca(OH) 2 produced by the hydration of CaO. Chloroacetylene (CA) and dichloroacetylene (DCA) were the primary byproducts of the decomposition of cis-DCE and TCE, respectively. The formation of DCA and CA was reduced by the presence of excess water for the hydration of added CaO. The instability of the CA and DCA in the presence of air resulted in the formation of additional secondary organic byproducts (e.g., PCE, CA, and hexachlorobutadiene for CaO-treated TCE; and trans-DCE, TCE, and vinyl chloride for CaO-treated cis-DCE). The maximum decomposition and dechlorination of chloroethylenes was encountered in experiments conducted at a CaO/H 2 O ratio of 1:1 in the presence of air. The estimated maximum amount of decomposition of PCE, TCE, and cis-DCE by the hydration of CaO was 0.3 %, 37.3 %, 63.2 %, respectively. The first experiment proves that destruction of chlorinated ethylene can occur to some degree during the hydration of CaO. The second experiment explored the reaction of chlorinated ethylenes with Ca(OH) 2 by focusing on experiments where TCE was added in direct contact with Ca(OH) 2 with different temperatures and times. The impact of temperature and time on the reaction was evaluated by measuring organic byproducts and extractable chloride. When TCE was exposed to Ca(OH) 2 , the formation of organic byproducts and chloride increased with increasing reaction temperature. However, the formation of DCA did not vary with reaction time. The formation of chloride slowed down as Ca(OH) 2 was converted to the extractable chlorine-compounds. The percent of chloride was 1.2 %, 2.1 %, and 3.7 % of TCE added at 60 o C, 80 o C, and 100 o C, respectively. 150

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Assuming the conversion of Ca(OH) 2 to CaCl 2 /CaOHCl, the degree of Ca(OH) 2 conversion did not exceed 0.22 %/0.11 %. In the third experiment, the fate of chlorinated ethylenes with CaO addition was evaluated in soil solution. Temperature rises in CaO-treated soils were measured with different mole ratios of CaO to water. Minimizing volatilization, dechlorination of chlorinated ethylenes in soil was determined when CaO was added to chlorinated ethylene-spiked soil with different CaO/H 2 O ratios. Dechlorination of the chlorinated ethylenes (cis-DCE, TCE, and PCE) increased with increasing CaO added. The degree of dechlorination varied among the different chlorinated ethylenes, with significant dechlorination of cis-DCE and TCE (up to 43 %, and 29 % of the initial cis-DCE and TCE); Dechlorination of PCE was not significant (4 % of the initial PCE). The amount of excess water for the hydration of CaO at a CaO/H 2 O of 1:2 reduced dechlorination of the chlorinated ethylenes because water prevented chloroethylene vapor from contacting Ca(OH) 2 . Dechlorination of chlorinated ethylenes was enhanced when the maximum temperature achieved by the addition of CaO increased. The first three experiments found that some degree of destruction of chlorinated ethylenes occurred by the CaO treatment, but these experiments were conducted under conditions where volatilization was minimized. In the fourth experiment, the impacts of volatilization on TCE removal from soil were examined when CaO was added to TCE-contaminated soil. TCE volatilization by different amounts of CaO doses in different soils was compared to those in the soils without CaO addition; the formation of decomposed products was measured as well. Increasing the amount of CaO dose in all of the soils reduced the time required to remove TCE. The results revealed that generating more heat with higher CaO doses overcame the obstacles retarding the TCE volatilization, for example a soil with high organic content or high clay 151

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content. When a 20 % CaO was added, the formation of an organic byproduct (i.e., DCA) was observed in traps collecting volatilized compounds. However, the formation of organic byproducts may not trigger a concern if an appropriate amount of CaO is used (5-10 % dose under the tested conditions). CaO addition was thought to be an alternative remediation technique to remove VOCs in soil if an appropriate CaO dose for volatile removal under siteand chemical-specific conditions was determined. In the fifth experiment, the impact of simulated post-CaO treatment conditions on TCE reduction and immobilization was examined. Simulated post-CaO-treated conditions were created by mixing a soil with Ca(OH) 2 . One-day and 7-day treatments of the test materials were conducted at 20 o C. To measure leachable TCE, the SPLP test was conducted. The TCE concentrations of the simulated materials and the concentrations of leachable TCE from the simulated materials were compared to those of TCE-contaminated soils. TCE reductions observed in the simulated post-CaO treated soils using a sandy clay loam (FB), a loamy sand (N), and a sand (AE) were greater than those in the TCE-contaminated soils. However, TCE reduction of the simulated post-CaO-treated a sandy loam (B) was less than that of the TCE-contaminated B soil. The levels of TCE in the simulated post-CaO-treated soils ranged from 17 % to 60 % of those in the TCE-contaminated soils by treating 1 day and 7 days. In contrast with these soils, the level of TCE in TCE-contaminated B soil ranged from 3 % to 67 % of that of simulated post-CaO-treated soil B. The amounts of TCE leached to the SPLP extracts from the tested materials were proportional to the total TCE concentrations of the materials, but no evidence of the immobilization of TCE was observed. 7.2 Conclusions This research reached the following specific conclusions: 152

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The decomposition of PCE by CaO treatment caused the formation of TCE. The estimated decomposition of PCE by mass balance with chlorine did not exceed more than 0.3 % of initial PCE under the experimental conditions. The degradation of TCE and cis-DCE was observed when CaO reacted with aqueous solution that mixed with TCE or cis-DCE at the CaO/H 2 O ratio of 1:1. The degradation of TCE and cis-DCE was enhanced by the presence of air. DCA and CA were the primary organic byproducts of the decomposition of TCE and cis-DCE when CaO reacted with the aqueous solution that was mixed with TCE or cis-DCE. The instability of DCA and CA at the CaO/H 2 O ratio of 1:1 and in the presence of air caused the formation of various organic byproducts (e.g., PCE, CA, and hexachlorobutadiene with TCE, and trans-DCE, TCE, and vinyl chloride with cis-DCE) and greater decomposition of TCE and cis-DCE than in the absence of air. The estimated maximum decomposed TCE and cis-DCE during the hydration of CaO was 37.3 % and 63.2 % of the initial amount of TCE and cis-DCE added to water, respectively. The formation of DCA and CA was reduced in the presence of excess water for the hydration of added CaO. The reduction of CA and DCA formed in the condition resulted in the reduction of the secondary organic byproducts. The increase of chloride concentrations in the materials formed with the hydration of CaO in the presence of TCE and cis-DCE suggested that the inorganic extractable-chlorine compounds formed as results of dechlorination of TCE and cis-DCE. The transformation of TCE to DCA, CA, and PCE increased with increasing temperature when TCE was directly exposed to Ca(OH) 2 . Extracted chloride was increased with increasing reaction temperature when TCE was exposed to Ca(OH) 2 . The transformation of TCE to DCA and extractable chloride compounds was not significant when TCE was directly exposed to Ca(OH) 2 at 20 o C. However, the results suggest that TCE can react to dry Ca(OH) 2 at an ambient temperature range. When TCE was exposed to Ca(OH) 2 , the ratios of Cl to Ca were 0.00007 () %at 20 o C for 12 hours, 0.0004() %, 0.0006(.7) %, 0.0011 (.6) %at 60 o C, 80 o C, and 100 o C for 5 hours. This results showed that most Ca(OH) 2 remained unreacted. When TCE was exposed to Ca(OH) 2 , the production of DCA did not vary with reaction time but the formation of chloride increased for first few hours and remained flat following the increase at 60 o C, 80 o C, and 100 o C. 153

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When TCE was exposed to Ca(OH) 2 at different temperature and time, the change of the Cl/DCA ratios suggested that the formation of chloride was due to not only HCl production by the dehydrochlorination of TCE with Ca(OH) 2 but also to other undiscovered reactions. When CaO was added to wet soil, soil temperature increased quickly but the change of temperature varied with the mole ratio of CaO to water, water content of the soil, and soil types. The temperature peaks caused by CaO addition were higher and occurred earlier in coarse sand than in loamy sand. The difference of temperature rise in coarse sand and loamy sand was likely caused by the different fraction of finer particles in soils that had large surface area and a strong affinity to water. When CaO was added to a soil contaminated by cis-DCE, TCE, or PCE, dechlorination of chlorinated ethylenes was increased by increasing the CaO/H 2 O ratio in soils. The maximum percent of dechlorination of the cis-DCE, TCE, and PCE were 43 %, 29 %, and 4 %, respectively at a CaO/H 2 O ratio of 1.5. The presence of excess water at the CaO/H 2 O ratio of 0.5 hindered dechlorination of chloroethylenes. It was revealed that increasing the water content in soil was the most effective way to reduce the dechlorination of chlorinated ethylenes by CaO addition. Dechlorination of chlorinated ethylenes in coarse sand was more prominent than in loamy sand. The different degree of the dechlorination in coarse sand and in loamy sand with the same CaO/H 2 O ratio was likely caused by the different temperature increases in the two soils. Removal of TCE from a soil using volatilization increased by increasing the CaO dose into the soil. Volatile removals of TCE in CaO-added soils for 3 hours resulted in 97 %-99 % removal of the initial TCE concentrations with 5 %, 10 %, and 20 % CaO doses in sand soils (e.g., AE soil and E soil). In loamy sand (B soil), TCE volatile removal ranged from79 % to 99 % with the same CaO doses. Enhanced TCE volatilization from soil by CaO addition revealed that generating more heat with higher CaO doses overcame the obstacles retarding the TCE volatilization, such as high organic content and clay content. The formation of DCA during TCE volatilization was observed with a 20 % CaO dose in all soils used. The largest quantity of DCA was also produced in sand soil (1.9 % clay, 0.13 % organic content) with a 20 % CaO dose. With a 10 % CaO dose, the formation of DCA during TCE volatilization was observed from one of three quicklime-treated sand soil samples (1.9 % clay, 0.13 % organic content). Reducing the formation of DCA and minimizing the amount of CaO addition, the optimum performance of TCE removal by CaO addition in 3-hour treatments was obtained with a range of 5 %-10 % CaO dose in sand (AE soil) with 0.55 % OC and 1.2 % clay, a 5 % CaO dose in sand 154

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(E soil) with 0.13 % OC and 1.9 % clay, and a 10 % CaO dose in loamy sand (B soil) with 0.06 % OC and 19.2 % clay. The results of TCE reduction and TCE leachability under post-CaO-treated conditions created by mixing Ca(OH) 2 to a soils showed that TCE reduction might occur in the soilCa(OH) 2 mixtures. A simple regression analysis showed that the reduction of leached TCE in the treated soils was not the result of immobilization by the treatment but because of the reduction of total TCE concentration in the treated soil. 7.3 Integration, Application, and Limitations In this dissertation, three feasible mechanisms affecting the fate of chlorinated ethylenes in soil by CaO addition were examined: (1) degradation of the chlorinated ethylenes, (2) volatilization of TCE, and (3) immobilization of TCE in the soil-Ca(OH) 2 matrix. The destruction of chlorinated ethylenes by CaO addition can occur for TCE and cis-DCE, with the reaction of the chemicals with Ca(OH) 2 being the main mechanism. Water content, temperature, reaction time, and the presence of air play a role in terms of quality and quantity of byproducts. Volatilization of chlorinated ethylenes plays a huge role and may be the most dominant process with regards to the removal of the chemicals in CaO-treated soil. However, no evidence of the immobilization of chlorinated ethylenes in soil-Ca(OH) 2 matrix was observed. This work focused on basic principles of the feasible mechanisms of chlorinated ethylenes with a laboratory scale. To apply and predict VOC-removal with CaO treatment (quicklime) under field conditions, other parameters should be considered such as quality of quicklime (CaO content), degree of mixing of quicklime and soil (how well the soil is being mixed with quicklime), the ratio of the exposed surface of the CaO-treated material to the ambient air, the depth of quicklime-treated material, ambient temperature, wind speed, chemical properties of contaminants. To use quicklime under full-scale field conditions, large-scale experiments are necessary. 155

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A remediation site of FDOT Fairbanks disposal pit, Florida, U.S.A, is an example of quicklime application on a contaminated soil (FDOT, 2002). At a site in Fairbanks, quicklime addition that was used to help materials handling resulted in unanticipated removal of several volatile organic compounds in the excavated soil. Interestingly, air sampling data from four sampling station on the perimeter and personal air samplers on workers in the site did not prove volatilization to be a major pathway of the pollutant removal. It is difficult to evaluate the major removal mechanism at the site since the information of the excavated soil (water content, organic content, and clay fraction), the area of quicklime-soil mixture lifts, and the quantity of soil treated daily were not documented. At this site, quicklime mixing with excavated soil was conducted with 5 % quicklime addition to the soil of 18-inch lifts. The average concentration of TCE back-calculated using 160 excavated soil samples was 0.98 mg/kg. At the site, the fraction of contaminants decomposed during the hydration of quicklime, particularly chlorinated ethylenes, might be negligible since the formation of organic byproducts of CaO-treated TCE along volatilization was not observed with 5 % CaO doses in the lab-scale experiments. Also, the excavated soil at the Fairbanks site likely had high water content since it was dewatered by pumping groundwater before being excavated. It is likely that VOCs in the excavated soil were removed by volatilization at the Fairbanks. The emission rates of VOCs during soil processing and mixing of quicklime, perhaps, were not high enough to be detected by air surveillance because of the dilution of contaminants by air. While applying quicklime addition as a tool for remediating a soil contaminated with VOCs, several issues need to be considered. The issues include factors influencing the quicklime treatment, toxic effects created by byproducts, and the emission of hazardous air pollutants (HAPs). The amounts of CaO (or quicklime) added, water content, and soil types were key 156

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factors in laboratory experiment to determine favorable conditions for volatile removal of target chemicals. The optimum range of CaO doses for TCE volatilization under the tested experimental conditions was 5 % 10 % CaO by weight and water content after CaO-treatment ranged 10 % 13 % by weight when the amount of soil used was about 2.5 cm in depth in the test vessel. To maximize volatile removals of chlorinated ethylenes and minimize the formation of byproducts by CaO addition, strategies are (1) increasing the temperature of the soil-CaO mixture using the mole ratio of CaO to water less than 1, (2) increasing the CaO dose when clay or organic content of the soil increases, 3) keeping the soil-CaO mixture wet by adding water before and after mixing quicklime, and (4) decreasing the depth of the soil-CaO mixture pile and increasing the surface of area contacting ambient air. The formation of toxic chemicals may be a concern during quicklime treatment in field application. To examine the potential toxic effects caused by a quicklime treatment, the formation of by-products of the CaO-treated chemicals should be examined. The method developed in Chapter 2 can be applied to determine the formation of byproducts. The organic byproducts formed in the lab experiments by CaO-treated TCE and cis-DCE include dichloroacetylene (neurotoxin and potential carcinogen), chloroacetylene, vinyl chloride (carcinogen), hexachlorobutadiene (potential carcinogen), trans-DCE (decreasing numbers of red blood cells), PCE (liver and kidney damage and potential carcinogen), and TCE (potential carcinogen). However, the quantities of byproducts are negligible if an appropriate CaO dose is used and enough water content is maintained. The emission of HAPs can limit a treatment rate of soil (an amount of soil treated per day). Florida’s Brownfields Cleanup Criteria allows air emission of hazardous air pollutant (HAP) during active remediation up to 2.5 kg of one HAP per day or 6.2 kg of total HAPs per day (62157

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785.700, F.A.C.). If the amount of emission exceeds the criteria, a separate air permit will be required. Thus, the amount of soil that can be treated without air emission treatment system will vary with the concentration of a contaminant in a soil. Concentrations of chlorinated ethylenes in a field site may vary because chlorinated ethylenes themselves have low solubility and are non-miscible with water. For instance, if a condensed phase of TCE is present in soil, particularly source areas, the concentration of TCE in the soil can be higher than those used in this study. Concentrations of TCE in a plume around the chemical source will be lower than the point of the contaminant and decrease gradually alone the distance from the source. If simulating a site similar to the scale of Fairbanks disposal pit with average TCE concentration of 0.98 mg/kg, the volume of a soil lift is 850 m 3 with a soil lift (0.46 m in depth) and a processing region (1,858 m 2 in area). Assuming that the treatment rate of soil excavated was one soil lift per day and the density of soil was 1600 kg/m 3 , the weight of CaO-treated soil per day was estimated to be 1,360,000 kg. So, TCE emission per day was estimated as 1.33 kg, if the level of TCE in treated soil meets SCTLs (leachability based, 0.03 mg/kg). If an average concentrations of TCE in soils is as high as the level of TCE used in the experiments (1,700 mg/kg) and the level of TCE is reduced by quicklime addition to meet the levels of TCE Florida’s soil clean target level (leachability based), the rate of soil treatment cannot be more than 0.92 m 3 (1,500 kg) soil per day. If a soil has a low concentration of VOCs, quicklime addition is likely applicable to achieve the cleanup target levels, as observed at the site of FDOT (Fairbanks disposal pit). If a soil contains a large quantity of VOCs, one event of quicklime addition to the soil may not be enough to achieve a certain soil target cleanup level. In this case, additional remediation of the material may be necessary. For example, TCE concentration in soils by CaO addition in the lab 158

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results (Chapter 5) was reduced from 1,600-1,700 mg/kg to 20-40 mg/kg in 3 hours. TCE concentrations of CaO-treated soils do not meet the SCTLs based on direct exposure. In this scenario, extending the period of treatment or further remedial action is required. However, various field conditions as mentioned above likely affect the efficiency of VOC removal with quicklime addition. Obtaining permission for the volatile removal may rely on the method of soil cleanup as well as the quantity and quality of the volatile contaminants in soil. Developing a system to collect contaminants volatilized during the quicklime addition can be an alternative. A combination of collecting volatilized chemicals and releasing chemicals to ambient air can be another option. For example, since extensive volatilization of chemicals likely occurs in the beginning of quicklime addition, the collection of VOCs is performed at the beginning of the treatment. The quicklime addition and mixing processes can be conducted in a building with emission control system. Releasing remaining VOCs to ambient air can be allowed after achieving a certain degree of VOC reduction in the soil. 159

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APPENDIX A COMPONENTS OF TEST VESSEL DESIGNED 44.4 mm 32mm 25mm 50.8 mm ~70mm 45o 45o 20mm connector #7 80mm180mm70 mm 30 mm 45o connector #25glass tube A Figure A-1. Components of a test vessel. A) a glass reactor with two sampling ports, B) Teflon plunger (side view and front view), and C) a Teflon cap for a sampling port. 160

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B ~14mm 28 mm13.16 mm 35 mm10.0 mm 2mm ~14mm 28 mm13.16 mm 35 mm10.0 mm 2mm C Figure A-1. Continued. 161

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APPENDIX B FLORIDA CLEANUP TARGET LEVELS Table B-1. Florida Soil Cleanup Target Levels (SCTLs). Direct Exposure Residential Commercial/ Industrial Leachability Based on Groundwater Criteria Contaminants CAS#s mg/kg mg/kg mg/kg Target Organs/Systems or Effects Chloroacetylene 593-63-5 NA NA NA NA Dichloroacetylene 156-59-2 NA NA NA NA Dichloroethene, cis-1,2 156-59-2 33 180 0.4 Blood Dichloroethene, trans-1,2156-60-5 53 290 0.7 Blood, liver Trichloroethene 79-01-6 6.4 9.3 0.03 Carcinogen None specified Tetrachloroethene 127-18-4 8.8 18 0.03 Carcinogen Liver Hexachloro-1,3-butadiene 87-68-3 NA NA NA NA Vinyl chloride 75-01-4 0.2 0.8 0.007 Carcinogen Liver NA indicates “not available in SCTLs”. Source: FDEP Chapter 62-777, F.A.C., Table II Soil Cleanup Target Levels Table B-2. Florida Groundwater and Surface Water Cleanup Target Levels (GSWCT). Groundwater Criteria Freshwater Surface Water Criteria Contaminants CAS#s g/L Hexachloro-1,3-butadiene 87-68-3 0.4 49.7 Source: FDEP Chapter 62-777, F.A.C. Groundwater and Surface Water Cleanup Target Levels (2005) 162

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APPENDIX C OCCUPATIONAL EXPOSURE LIMITS Table C-1. Occupational Exposure Limits an 8-hour workday (40-hour workweek) Contaminants CAS#s ppm (uL/L) Chloroacetylene 593-63-5 NA Dichloroacetylene 156-59-2 0.1 Dichloroethene, cis-1,2 156-59-2 200 Dichloroethene, trans-1,2156-60-5 200 Hexachloro-1,3-butadiene 87-68-3 0.02 Trichloroethene 79-01-6 100 Tetrachloroethene 127-18-4 100 Vinyl chloride 75-01-4 1.0 NA indicates “not available”. : Recommended exposure limit by the National Institute for Occupational Safety and Health (NIOSH). Source: 29 CFR 1910.1000. 163

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APPENDIX D X-RAY DIFFRACTION PATTERNS OF SOILS USED IN CHAPTER 6 QKIQQKIQ QKIQQKIQ Figure D-1. AE soil X-ray diffraction patterns. Clay w/Mg-Gly indicate clay fraction with Mg saturation and glycerol salvation. Clay w/KCl indicates clay with K saturation. KI = kaolinite and Q= quartz. Clay w/ MG GlyClay w/ KClSiltKIQQKIQQ Clay w/ MG GlyClay w/ KClSiltKIQQKIQQ Figure D-2. B soil X-ray diffraction patterns. Clay w/Mg-Gly indicate clay fraction with Mg saturation and glycerol salvation. Clay w/KCl indicates clay with K saturation. KI = kaolinite and Q= quartz. 164

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KIGbQKIQQQQ KIGbQKIQQQQ Figure D-3. N soil X-ray diffraction patterns. Clay w/Mg-Gly indicate clay fraction with Mg saturation and glycerol salvation. Clay w/KCl indicates clay with K saturation. KI = kaolinite, Gb = gibbsite and Q= quartz. Clay w/ MG GlyClay w/ KClSiltKIQKIQQ Clay w/ MG GlyClay w/ KClSiltKIQKIQQ Figure D-4. FB soil X-ray diffraction patterns. Clay w/Mg-Gly indicate clay fraction with Mg saturation and glycerol salvation. Clay w/KCl indicates clay with K saturation. KI = kaolinite and Q= quartz. 165

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Grifoll J., and Cohen Y.(1994). “Chemical Volatilization from the Soil Matrix: Transport through the Air and Water Phase,” J. Hazard. Mater., 37:445-457 Gu, B. and Siegrist, R.L.(1997). “Dehalogenation of Chlorinated Organic Compounds by Strong Alkalis,” J. Environ. Eng., October 1997:982-987 Guenzi, W.D., and Beard, W. E.(1974). Pesticides in Soil and Water , Soil Science Society of America, Madison WI, USA. Hall, A.K., Harrowfileld, J.M., Hart, R.J., and Mccormick, P.G.(1996). “Mechanochemical Reaction of DDT with Calcium Oxide,” Environ. Sci. Technol., 30(12):3401-3407. Jozefacuk, G. and Bowanko, G.(2002). “Effect of Acid and Alkali Treatments on Surface Area and Adsorption Energies of Selected Minerals,” Clays and Clay Min., 50(6) 771-783 Koper, O., Li, Y., and Klabunde K. J.(1993). “Destructive Adsorption of Chlorinated Hydrocarbons on Ultrafine (Nanoscale) Particles of Calcium Oxide,” Chem. Mater., 5:500-505. Koper, O., Lagadic, L., Klabunde, K. J.(1997). “Destructive Adsorption of Chlorinated Hydrocarbons on Ultrafine (Nanoscale) Particles of Calcium Oxide 2,” Chem. Mater., 9:838-848 Koper, O., and Klabunde, K. J.(1997). “Destructive Adsorption of Chlorinated Hydrocarbons on Ultrafine (Nanoscale) Particles of Calcium Oxide. 3. Chloroform, Trichloroethene, and Tetrachloroethene,” Chem. Mater., 9:2481-2485. Kossan,D.S., van der Sloot,H.A., Sanchez,F., Garrabrants,A.C.(2002). “An Integrated Framework for Evaluating Leaching in Waste Management and Utilization of Secondary Materials,” Environ. Eng. Sci 19(3):159-203. Levenspiel, O. (1972), Chemical Reaction Engineering , Second Edition, John Willy & Sons, New York, NY, USA. Loiselle, S., Branca, M., Mulas, G., and CoccO, G.(1997). “Selective Mechanochemical Dehalogenation of Chlorobenzenes over Calcium Hydride,” Environ. Sci. Technol., 31:261-265 Marion, G.M., Payne, J.R., and Brar, G. S.(1997). Site Remediation via Dispersion by Chemical Reaction (DCR) , U.S. Army Corps of Engineers, Cold Regions Research & Engineering Laboratory, Special Report 97-18. Matsumoto, M., Morita, Y., Hayashi, J.,Kawamoto, H.(1995). Method of Removing Volatile Chlorinated Hydrocarbon Base Materials, US Patent, 5,416,248 167

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Morgan, D.S., Novoa, J.I., and Halff, A.H.(1984). “Oil Sludge Solidification Using Cement Kiln Dust,” J of Environ. Eng., 100(5), 935-948. NLA (National Lime Association) (2004). Consideration of Lime-stabilized Layers in Mechaqnistic-Empirical Pavement Design , http://www.lime.org/MechEmpPavement.pdf , April 2007. Ong S.K. and Lion L.W.(1991). “Mechanisms for Trichloroethylene Vapor Sorption onto Soil Minerals,” J. Environ. Qual., 20 (1): 180-188. Pasquato, L., Modena, G., Cotarca, L, Delogu, P., and Mantovani, S.(2000), “Conversion of Bis(trichloromethyl) Carbonate to Phosgene and Reactivity of Triphosgene, Diphosgene, and Phosgene with Methanol,” J. Org. Chem., 65:8224-8228 Ritchie, I. M., and Bing-an, X.(1990). “The Kinetic of Lime Slaking,” Hydrometallurgy, 23:377-396 Sedlak, D. L., Dean, K. E., Armstrong, D. E., and Andren, A.W.(1991). “Interaction of Quicklime with Polychlorobiphenyl Contaminated Solids,” Environ. Sci. Technol., 25(11):1936-1940. Smith, K.A., Goins, L.E., and Logan, T. J.(1998), “Effect of Calcium Oxide Dose on Thermal Reactions, Lime Speciation, and Physical Properties of Alkaline Stabilized Biosolids,” Water Environ. Res., 70( 2):224-230. Soundararajan, R, (1991)., Final Report on the “Disappearing PCBs” project . RMC Environmental and Analytical Laboratories, Feb 4, 1991. Found in Appendix A of USEP (1991). Townsend, T., Dubey,B., Tolaymat,T.(2006). “Interpretation of Synthetic Precipitation Leaching Procedure (SPLP) Results for Assessing Risk to Groundwater from Land-applied Granular Waste,” Environ. Eng. Sci., 23(1):239-251 TRB(Transportation Research Board)(1987). Lime Stabilization-Reaction, Properties, Design, and Construction , Washington, D.C., USA. USEPA (1991). Fate of Polychlorinated Biphenyls (PCBs) in Soil Following Stabilization with Quicklime. , Risk Reduction Engineering Laboratory, Cincinnati, OH. USEPA (1996). Soil Screening Guidance: User’s Guide , Second edition, Office of Emergency and Remedial Response, U.S. Environmental Protection Agency, Washington, DC. U.S.A. USEPA, Test Methods for Evaluating Solid Waste, Physical/Chemical Methods, SW 846 on-line, http://www.epa.gov/epaoswer/hazwaste/test/main.htm , April 2007. 168

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BIOGRAPHICAL SKETCH Jae Hac Ko was born on September 27, 1971, to Byungju Ko and Yongja Kim at Namwon, Jeju, Republic of Korea. He graduated from Cheju (Jeju) National University with a bachelor’s degree in environmental engineering in 1998. He received his master’s degree in environmental engineering from University of Seoul in 2000. He began as a graduate student in the Department of Environmental Engineering Sciences at the University of Florida in fall 2002. He received his PhD in environmental engineering in 2007 with the guidance of Dr. Timothy Townsend. 170