Not available / text

published_or_final_version / abstract / Botany / Master / Master of Philosophy

High atmospheric concentrations of CO2 contribute to adverse effects that impact human health and the climate. The need to reduce CO2 is evident, and climate stabilization will require a combination of mitigation, utilization, and even negative emission technologies. Thus, one key approach will be to transform abundant CO2 into a useful feedstock for processes that not only produce value-added products but also match the scale necessary to impact anthropogenic emissions. The tandem CO2 reduction and light alkane transformation reactions over specialized bifunctional catalysts have the potential to produce olefins or synthesis gas by efficiently utilizing the C2-C4 components in shale gas while reducing a greenhouse gas. The reactions of CO2 with light alkanes may occur through two distinct pathways, oxidative dehydrogenation (CO2 + CnH2n+2 → CnH2n + CO + H2O, CO2-ODH) and dry reforming (nCO2 + CnH2n+2 → 2nCO + (n+1)H2, DR). The two reactions can occur simultaneously at temperatures ≥823 K with considerable conversions. Until recently, there has been little understanding regarding the identification of bimetallic catalytic systems that either selectively cleave the C-H bonds to produce olefins or effectively break all the C-C and C-H bonds to produce dry reforming products. In this work, we discuss a combined approach of flow reactor experiments, in situ characterization, and density functional theory (DFT) calculations to help create a design platform for catalysts that are inherently active and selective for the reactions of CO2 and light alkanes. Particularly, it was of interest to use propane as CO2 reduction feedstock due to its increasing abundance and highly marketable respective olefin. Through the combined approach, non-precious Fe3Ni1 and precious Ni3Pt1 supported on CeO2 were identified as promising catalysts for the CO2-ODH and DR of propane, respectively. In situ X-ray absorption spectroscopy measurements revealed the oxidation states of metals under reaction conditions and DFT calculations were utilized to identify the most favorable reaction pathways over the two types of catalysts. While both the CO2-ODH and DR reactions of alkanes produce valuable molecules, the separation of gas phase products is challenging. Therefore, it was highly desirable to develop a tandem reaction scheme in which the reaction of CO2 and alkanes can produce liquid products. Another potential chemistry with increased similarity to the operating conditions of CO2-ODH, is the tandem reactions of CO2-assisted oxidative dehydrogenation and aromatization of light alkanes (CO2-ODA). In this process, alkanes are transformed directly into aromatics without the need for expensive naphtha while increasing the consumption of CO2 per mol of value-added product and facilitating downstream separation because of the production of liquid aromatics. One critical change upon the introduction of CO2 to the dehydrogenation/aromatization pathway is the formation of water. The presence of water under reaction conditions has been shown to be problematic for zeolites as it causes changes in the framework. Phosphorous modification at an optimal loading improved the hydrothermal stability of Ga/ZSM-5, reduced coke formation on the catalyst surface, and allowed for the formation of more liquid aromatics through the CO2-ODAE reaction pathway compared to the direct dehydrogenation and aromatization reaction. With the aid of DFT calculations, the mechanisms for the production of aromatics from ethane were identified, providing insight on the effect of Ga modification on ethylene formation over ZSM-5 as well as the role of CO2 on the aromatization of ethylene. Future efforts should be geared toward enhancing aromatics yield through the design of hydrothermal stable zeolite-based materials with bimetallic active centers that are capable of activating CO2.

Lau Kan Lung. / Thesis submitted in: November 2001. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 286-312). / Abstracts in English and Chinese. / List of Symbols and Abbreviations --- p.I / List of Figures --- p.III / List of Tables --- p.XII / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Polycyclic aromatic hydrocarbons (PAHs) --- p.1 / Chapter 1.1.1 --- Physical and chemical properties of PAHs --- p.1 / Chapter 1.1.2 --- Formation of PAHs --- p.5 / Chapter 1.1.3 --- Sources of PAHs --- p.9 / Chapter 1.1.4 --- Regulations for contamination of PAHs --- p.13 / Chapter 1.1.5 --- Pollution of PAHs in environments of Hong Kong --- p.17 / Chapter 1.1.6 --- Toxicity of PAHs --- p.18 / Chapter 1.1.7 --- Fate of PAHs --- p.22 / Chapter 1.1.7.1 --- Sorption --- p.24 / Chapter 1.1.7.2 --- Volatilization --- p.25 / Chapter 1.1.7.3 --- Photooxidation --- p.25 / Chapter 1.1.7.4 --- Chemical oxidation --- p.27 / Chapter 1.1.7.5 --- Microbial degradation --- p.28 / Chapter 1.1.8 --- General principles of metabolism of PAHs --- p.30 / Chapter 1.2 --- Spent mushroom compost (SMC) --- p.35 / Chapter 1.2.1 --- Production of SMC --- p.35 / Chapter 1.2.2 --- Physical and chemical properties of SMC --- p.36 / Chapter 1.2.3 --- Availability of SMC --- p.40 / Chapter 1.2.4 --- Conventional applications of SMC --- p.43 / Chapter 1.2.5 --- Alternate use of SMC --- p.44 / Chapter 1.3 --- Objectives of the study --- p.48 / Chapter 1.4 --- Research strategy --- p.51 / Chapter 1.4.1 --- Effect of initial PAH concentration --- p.51 / Chapter 1.4.2 --- Effect of initial pH --- p.52 / Chapter 1.4.3 --- Effect of incubation time --- p.53 / Chapter 1.4.4 --- Effect of incubation temperature --- p.54 / Chapter 1.4.5 --- Putative identification of intermediates and/or breakdown products --- p.54 / Chapter 1.4.6 --- Isotherm plots and fitting into monolayer models --- p.55 / Chapter 1.4.6.1 --- Langmuir isotherm --- p.56 / Chapter 1.4.6.2 --- Freundlich isotherm --- p.58 / Chapter 1.4.7 --- Toxicological study by Microtox test --- p.59 / Chapter 1.4.8 --- Removal of PAH mixtures --- p.60 / Chapter 1.4.9 --- Specific goals of the study --- p.61 / Chapter 2 --- Materials and Methods --- p.62 / Chapter 2.1 --- Materials --- p.62 / Chapter 2.2 --- Physical and chemical analysis of SMC --- p.62 / Chapter 2.2.1 --- pH --- p.63 / Chapter 2.2.2 --- Electrical conductivity --- p.63 / Chapter 2.2.3 --- Salinity --- p.63 / Chapter 2.2.4 --- Ash content --- p.63 / Chapter 2.2.5 --- Metal contents --- p.64 / Chapter 2.2.6 --- Water-soluble anion contents --- p.65 / Chapter 2.2.7 --- "Carbon, hydrogen, nitrogen and sulfur contents" --- p.65 / Chapter 2.2.8 --- Infrared spectroscopic study --- p.66 / Chapter 2.2.9 --- Chitin content --- p.66 / Chapter 2.3 --- Soil collection and characterization --- p.67 / Chapter 2.4 --- Optimization for extraction --- p.67 / Chapter 2.5 --- Removal of PAHs --- p.68 / Chapter 2.5.1 --- Experimental design --- p.68 / Chapter 2.5.1.1 --- Pretreatment and incubation --- p.68 / Chapter 2.5.1.2 --- Extraction of sorbed PAHs in soil system or in SMC --- p.69 / Chapter 2.5.1.3 --- Extraction of PAHs in water system --- p.70 / Chapter 2.5.1.4 --- Putative identification and quantification of PAHs --- p.71 / Chapter 2.5.2 --- Assessment criteria --- p.72 / Chapter 2.5.3 --- Stability of PAHs --- p.77 / Chapter 2.5.4 --- Optimization for removal of PAHs --- p.78 / Chapter 2.5.4.1 --- Effects of initial PAH concentration and amount of SMC --- p.78 / Chapter 2.5.4.2 --- Effect of initial pH --- p.79 / Chapter 2.5.4.3 --- Effect of incubation time --- p.79 / Chapter 2.5.4.4 --- Effect of incubation temperature --- p.79 / Chapter 2.5.5 --- Putative identification of intermediates and/or breakdown products --- p.80 / Chapter 2.5.6 --- Isotherm plots and fitting into monolayer models --- p.80 / Chapter 2.5.6.1 --- Langmuir isotherm --- p.80 / Chapter 2.5.6.2 --- Freundlich isotherm --- p.81 / Chapter 2.5.7 --- Toxicological study of Microtox® test --- p.82 / Chapter 2.5.8 --- Removal ability of SMC towards PAHs in single and in a mixture --- p.82 / Chapter 2.5.9 --- Removal abilities of different sorbents towards PAHs in water --- p.83 / Chapter 2.5.10 --- Removal abilities of raw and autoclaved SMC towards PAHs in water --- p.83 / Chapter 2.5.11 --- Statistical validation --- p.83 / Chapter 3 --- Results --- p.85 / Chapter 3.1 --- Characterization of soil --- p.85 / Chapter 3.1.1 --- Physical and chemical properties of soil --- p.85 / Chapter 3.1.2 --- GC-MS analysis of soil --- p.85 / Chapter 3.2 --- Calibration curves of PAHs --- p.85 / Chapter 3.3 --- Optimization for extraction --- p.91 / Chapter 3.4 --- Stability of PAHs --- p.101 / Chapter 3.4.1 --- Soil system --- p.101 / Chapter 3.4.1.1 --- Effect of incubation time --- p.101 / Chapter 3.4.1.2 --- Effect of incubation temperature --- p.101 / Chapter 3.4.2 --- Water system --- p.103 / Chapter 3.4.2.1 --- Effect of incubation time --- p.103 / Chapter 3.4.2.2 --- Effect of incubation temperature --- p.103 / Chapter 3.5 --- Characterization of SMC --- p.103 / Chapter 3.5.1 --- Physical and chemical properties of SMC --- p.103 / Chapter 3.5.2 --- GC-MS analysis of SMC --- p.106 / Chapter 3.5.3 --- Infrared spectroscopic study and chitin content --- p.106 / Chapter 3.5.4 --- Removal abilities of different sorbents towards PAHs in water --- p.121 / Chapter 3.5.5 --- Removal abilities of raw and autoclaved SMC towards PAHs in water --- p.121 / Chapter 3.6 --- Optimization for removal of PAHs --- p.124 / Chapter 3.6.1 --- Naphthalene --- p.124 / Chapter 3.6.1.1 --- Soil system --- p.124 / Chapter 3.6.1.1.1 --- Effects of initial naphthalene concentration and amount of straw SMC on removal efficiency --- p.124 / Chapter 3.6.1.1.2 --- Effects of initial naphthalene concentration and amount of straw SMC on removal capacity --- p.128 / Chapter 3.6.1.1.3 --- Effect of initial pH --- p.128 / Chapter 3.6.1.1.4 --- Effect of incubation time --- p.128 / Chapter 3.6.1.1.5 --- Effect of incubation temperature --- p.131 / Chapter 3.6.1.1.6 --- Putative identification of intermediates and/or breakdown products --- p.131 / Chapter 3.6.1.2 --- Water system --- p.134 / Chapter 3.6.1.2.1 --- Effects of initial naphthalene concentration and amount of straw SMC on removal efficiency --- p.134 / Chapter 3.6.1.2.2 --- Effects of initial naphthalene concentration and amount of straw SMC on removal capacity --- p.137 / Chapter 3.6.1.2.3 --- Effect of initial pH --- p.137 / Chapter 3.6.1.2.4 --- Effect of incubation time --- p.139 / Chapter 3.6.1.2.5 --- Effect of incubation temperature --- p.139 / Chapter 3.6.1.2.6 --- Putative identification of intermediates and/or breakdown products --- p.143 / Chapter 3.6.2 --- Phenanthrene --- p.145 / Chapter 3.6.2.1 --- Soil system --- p.145 / Chapter 3.6.2.1.1 --- Effects of initial phenanthrene concentration and amount of straw SMC on removal efficiency --- p.145 / Chapter 3.6.2.1.2 --- Effects of initial phenanthrene concentration and amount of straw SMC on removal capacity --- p.145 / Chapter 3.6.2.1.3 --- Effect of initial pH --- p.148 / Chapter 3.6.2.1.4 --- Effect of incubation time --- p.148 / Chapter 3.6.2.1.5 --- Effect of incubation temperature --- p.151 / Chapter 3.6.2.1.6 --- Putative identification of intermediates and/or breakdown products --- p.151 / Chapter 3.6.2.2 --- Water system --- p.155 / Chapter 3.6.2.2.1 --- Effects of initial phenanthrene concentration and amount of straw SMC on removal efficiency --- p.155 / Chapter 3.6.2.2.2 --- Effects of initial phenanthrene concentration and amount of straw SMC on removal capacity --- p.155 / Chapter 3.6.2.2.3 --- Effect of initial pH --- p.157 / Chapter 3.6.2.2.4 --- Effect of incubation time --- p.157 / Chapter 3.6.2.2.5 --- Effect of incubation temperature --- p.161 / Chapter 3.6.2.2.6 --- Putative identification of intermediates and/or breakdown products --- p.163 / Chapter 3.6.3 --- Benzo[a]pyrene --- p.163 / Chapter 3.6.3.1 --- Soil system --- p.163 / Chapter 3.6.3.1.1 --- Effects of initial benzo[a]pyrene concentration and amount of straw SMC on removal efficiency --- p.163 / Chapter 3.6.3.1.2 --- Effects of initial benzo[a]pyrene concentration and amount of straw SMC on removal capacity --- p.167 / Chapter 3.6.3.1.3 --- Effect of initial pH --- p.167 / Chapter 3.6.3.1.4 --- Effect of incubation time --- p.168 / Chapter 3.6.3.1.5 --- Effect of incubation temperature --- p.168 / Chapter 3.6.3.1.6 --- Putative identification of intermediates and/or breakdown products --- p.172 / Chapter 3.6.3.2 --- Water system --- p.172 / Chapter 3.6.3.2.1 --- Effects of initial benzo[a]pyrene concentration and amount of straw SMC on removal efficiency --- p.172 / Chapter 3.6.3.2.2 --- Effects of initial benzo[a]pyrene concentration and amount of straw SMC on removal capacity --- p.176 / Chapter 3.6.3.2.3 --- Effect of initial pH --- p.178 / Chapter 3.6.3.2.4 --- Effect of incubation time --- p.178 / Chapter 3.6.3.2.5 --- Effect of incubation temperature --- p.181 / Chapter 3.6.3.2.6 --- Putative identification of intermediates and/or breakdown products --- p.183 / Chapter 3.6.4 --- "Benzo[g,h,i]perylene" --- p.183 / Chapter 3.6.4.1 --- Soil system --- p.183 / Chapter 3.6.4.1.1 --- "Effects of initial benzo[g,h,i]perylene concentration and amount of straw SMC on removal efficiency" --- p.183 / Chapter 3.6.4.1.2 --- "Effects of initial benzo[g,h,i]perylene concentration and amount of straw SMC on removal capacity" --- p.187 / Chapter 3.6.4.1.3 --- Effect of initial pH --- p.187 / Chapter 3.6.4.1.4 --- Effect of incubation time --- p.187 / Chapter 3.6.4.1.5 --- Effect of incubation temperature --- p.189 / Chapter 3.6.4.1.6 --- Putative identification of intermediates and/or breakdown products --- p.189 / Chapter 3.6.4.2 --- Water system --- p.192 / Chapter 3.6.4.2.1 --- "Effects of initial benzo[g,h,i]perylene concentration and amount of straw SMC on removal efficiency" --- p.192 / Chapter 3.6.4.2.2 --- "Effects of initial benzo[g,h,i]perylene concentration and amount of straw SMC on removal capacity" --- p.196 / Chapter 3.6.4.2.3 --- Effect of initial pH --- p.198 / Chapter 3.6.4.2.4 --- Effect of incubation time --- p.198 / Chapter 3.6.4.2.5 --- Effect of incubation temperature --- p.198 / Chapter 3.6.4.2.6 --- Putative identification of intermediates and/or breakdown products --- p.201 / Chapter 3.7 --- Isotherm plots and fitting into monolayer models --- p.205 / Chapter 3.7.1 --- Sorption of naphthalene --- p.205 / Chapter 3.7.2 --- Sorption of phenanthrene --- p.205 / Chapter 3.7.3 --- Sorption of benzo[a]pyrene --- p.208 / Chapter 3.7.4 --- "Sorption of benzo[g,h,i]perylene" --- p.208 / Chapter 3.8 --- Toxicological study of Microtox test --- p.208 / Chapter 3.8.1 --- Soil system --- p.214 / Chapter 3.8.2 --- Water system --- p.214 / Chapter 3.9 --- Operable conditions of SMC for removal of PAHs --- p.214 / Chapter 3.10 --- Removal ability of SMC towards PAHs in single and in a mixture --- p.214 / Chapter 3.10.1 --- Soil system --- p.216 / Chapter 3.10.2 --- Water system --- p.216 / Chapter 4 --- Discussion --- p.221 / Chapter 4.1 --- Characterization of SMC --- p.221 / Chapter 4.2 --- Removal abilities of different sorbents towards PAHs in water --- p.223 / Chapter 4.3 --- Removal abilities of raw and autoclaved SMC towards PAHs in water --- p.226 / Chapter 4.4 --- Extraction efficiencies of PAHs --- p.227 / Chapter 4.5 --- Factors affecting removal of PAHs by SMC --- p.229 / Chapter 4.5.1 --- Initial PAH concentration and amount of straw SMC --- p.229 / Chapter 4.5.2 --- Initial pH --- p.237 / Chapter 4.5.3 --- Incubation time --- p.237 / Chapter 4.5.4 --- Incubation temperature --- p.242 / Chapter 4.6 --- Putative identification of intermediates and/or breakdown products --- p.247 / Chapter 4.7 --- Isotherm plots and fitting into monolayer models --- p.257 / Chapter 4.8 --- Toxicological study of Microtox® test --- p.258 / Chapter 4.9 --- Removal ability of SMC towards PAHs in single and in a mixture --- p.261 / Chapter 4.10 --- Comparison of removal efficiencies of benzo[a]pyrene by layering and mixing of straw SMC with soil --- p.265 / Chapter 4.11 --- Comparison of removal efficiencies of benzo[a]pyrene in different scales of experiment setup --- p.267 / Chapter 4.12 --- Effect of age of straw SMC on removal of PAHs --- p.270 / Chapter 4.13 --- Removal of benzo[a]pyrene by an aqueous extract of SMC --- p.270 / Chapter 4.14 --- Advantages of using SMC in removal of PAHs --- p.273 / Chapter 4.15 --- Limitations of the study --- p.278 / Chapter 4.16 --- Further investigation --- p.280 / Chapter 5 --- Summary --- p.282 / Chapter 6 --- Conclusion --- p.285 / Chapter 7 --- References --- p.286

by Jian Wang. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (p. 154-171). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.

Sites contaminated with polyaromatic hydrocarbons (PAHs) pose serious health and safety risks to the surrounding environment due to their toxicity, persistence and accumulation in the environment. Because certain members of this class have been demonstrated to be both carcinogenic and mutagenic, PAHs are considered as environmental priority pollutants (US EPA). The studies in this thesis provide an efficient, economical and environmentally benign technique for the remediation of PAH contaminated soil/sediment by means of PAH mobilization with surfactant followed with a catalytic hydrogenation in supercritical carbon dioxide (scCO2). / Catalytic hydrogenation of naphthalene, acenaphthylene, ancenaphthene, anthracene, phenanthrene, chrysene and benzo[a]pyrene over alumina supported palladium (5% Pd0/gammaAl2O3) commercial catalyst were investigated in either a batch reaction mode or a continuous reaction system in H2-scCO2 (∼5% v/v). The hydrocarbon compounds were efficiently reduced to their corresponding fully saturated polycyclic hydrocarbon homologs with mild conditions of temperature (90°C) and pressure (60 psi H2 or 3000 psi H2-scCO2). The bacterial reverse mutation assay demonstrated that both the fully and partially hydrogenated products of chrysene and benzo[a]pyrene were devoid of mutagenic activity. / A laboratory study was conducted on the surfactant-assisted mobilization of PAH compounds combined with reagent regeneration and detoxification steps to generate innocuous products. Five minutes of ultrasonication of field contaminated soil with a 3% (w/v) surfactant suspension mobilized appreciable quantities of all PAH compounds. Formulating the Brij 98 surfactant in 0.1 M phosphate buffer (pH 8.0) mobilized the largest quantities of PAH compounds and the recovery of surfactant (>90%) but soil residues exceeded permissible maxima for five- and six-ring analytes. Five successive washes were required to reduce the residual fraction to permissible levels. The mobilized PAH compounds were then detoxified at line by catalytic hydrogenation in a 5% H2-scCO2 (v/v) atmosphere. / New palladium hydrogenation catalysts were fabricated in the laboratory with specific processes on various supports. The hydrogenation of phenanthrene and benzo[a]pyrene in a fixed bed micro reactor demonstrated that the catalyst that was fabricated from organosoluble precursor loaded on aluminum oxide (2.5% Pd0/gammaAl2O3) was four times more efficient than the commercial catalyst that was used for PAH hydrogenations.

No description available.

Yip, Ho-yin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 181-201). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / Contents --- p.vi / List of Figures --- p.x / List of Tables --- p.xvii / Abbreviations --- p.xix / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Polycyclic aromatic hydrocarbons (PAHs) --- p.1 / Chapter 1.1.1 --- Characteristics of PAHs --- p.1 / Chapter 1.1.2 --- Sources of PAHs --- p.2 / Chapter 1.1.3 --- Environmental fates of PAHs --- p.3 / Chapter 1.1.4 --- Effects of PAHs on living organisms --- p.5 / Chapter 1.1.4.1 --- General effects --- p.5 / Chapter 1.1.4.2 --- Effects on plants --- p.6 / Chapter 1.1.4.3 --- Effects on invertebrates --- p.7 / Chapter 1.1.4.4 --- Effects on fishes --- p.7 / Chapter 1.1.4.5 --- Effects on reptiles and amphibians --- p.8 / Chapter 1.1.4.6 --- Effects on birds --- p.9 / Chapter 1.1.4.7 --- Effects on mammals --- p.9 / Chapter 1.2 --- PAH contamination in Hong Kong --- p.10 / Chapter 1.3 --- Treatments of PAH contamination --- p.12 / Chapter 1.3.1 --- Physical treatments --- p.12 / Chapter 1.3.2 --- Chemical treatments --- p.13 / Chapter 1.3.3 --- Biological treatments --- p.14 / Chapter 1.4 --- Advanced oxidation processes (AOPs) --- p.16 / Chapter 1.5 --- Summary --- p.24 / Chapter 2. --- Objectives --- p.27 / Chapter 3. --- Materials and Methods --- p.28 / Chapter 3.1 --- Chemicals --- p.28 / Chapter 3.2 --- Photocatalytic reactor --- p.30 / Chapter 3.3 --- Determination of PAHs concentrations --- p.30 / Chapter 3.3.1 --- Extraction of PAHs --- p.30 / Chapter 3.3.2 --- Quantification of PAHs --- p.32 / Chapter 3.4 --- Optimization of physico-chemical conditions for PCO --- p.37 / Chapter 3.4.1 --- Determination of the reaction time for optimization of PCO --- p.37 / Chapter 3.4.2 --- Effect of titanium dioxide (Ti02) concentration and light intensity --- p.38 / Chapter 3.4.3 --- Effect of initial pH and hydrogen peroxide (H2O2) concentration --- p.38 / Chapter 3.4.4 --- Effect of initial PAHs concentration --- p.39 / Chapter 3.5 --- Toxicity analysis --- p.39 / Chapter 3.5.1 --- Microtox® test for acute toxicity --- p.39 / Chapter 3.5.2 --- Mutatox® test for genotoxicity --- p.42 / Chapter 3.6 --- Determination of total organic carbon (TOC) removal in optimized PCO --- p.43 / Chapter 3.7 --- Determination of degradation pathways --- p.43 / Chapter 3.7.1 --- Extraction of intermediates and/or degradation products --- p.45 / Chapter 3.7.2 --- Identification of intermediates and/or degradation products --- p.45 / Chapter 4. --- Results --- p.49 / Chapter 4.1 --- Determination of PAHs concentrations --- p.49 / Chapter 4.2 --- Optimization of extraction method --- p.49 / Chapter 4.3 --- Optimization of physico-chemical conditions for PCO --- p.49 / Chapter 4.3.1 --- Determination of the reaction time for optimization of PCO --- p.49 / Chapter 4.3.2 --- Effect of Ti02 concentration and light intensity --- p.60 / Chapter 4.3.3 --- Effect of initial pH --- p.88 / Chapter 4.3.4 --- Effect of initial H2O2 concentration --- p.99 / Chapter 4.3.5 --- Effect of initial PAHs concentration --- p.104 / Chapter 4.3.6 --- Improvements on removal efficiency (RE) after optimization --- p.113 / Chapter 4.4 --- Toxicity analysis --- p.122 / Chapter 4.4.1 --- Microtox® test for acute toxicity --- p.122 / Chapter 4.4.2 --- Mutatox® test for genotoxicity --- p.122 / Chapter 4.5 --- Determination of TOC removal in optimized PCO --- p.129 / Chapter 4.6 --- Determination of degradation pathways --- p.129 / Chapter 5. --- Discussion --- p.150 / Chapter 5.1 --- Determination of PAHs concentrations --- p.150 / Chapter 5.2 --- Optimization of extraction method --- p.150 / Chapter 5.3 --- Optimization of physico-chemical conditions for PCO --- p.151 / Chapter 5.3.1 --- Determination of the reaction time for optimization of PCO --- p.151 / Chapter 5.3.2 --- Effects of Ti02 concentration and light intensity --- p.152 / Chapter 5.3.3 --- Effects of initial pH --- p.160 / Chapter 5.3.4 --- Effects of initial H202 concentration --- p.163 / Chapter 5.3.5 --- Effects of initial PAHs concentration --- p.165 / Chapter 5.3.6 --- Improvements on RE after optimization --- p.167 / Chapter 5.4 --- Toxicity analysis --- p.169 / Chapter 5.4.1 --- Microtox® test for acute toxicity --- p.169 / Chapter 5.4.2 --- Mutatox® test for genotoxicity --- p.170 / Chapter 5.5 --- Determination of TOC removal in optimized PCO --- p.171 / Chapter 5.6 --- Determination of detoxification pathways --- p.172 / Chapter 6. --- Conclusion --- p.177 / Chapter 7. --- References --- p.181 / Chapter 8. --- Appendix I --- p.202

published_or_final_version / Earth Sciences / Master / Master of Philosophy

Ambient observations have indicated that ozone formation in the Houston area is frequently faster and more efficient, with respect to NOx consumed, than other urban areas in the country. It is believed that these unique characteristics of ozone formation in the Houston area are associated with the plumes of reactive hydrocarbons, emanating from the industrial Houston Ship Channel area. Thus, accurate quantification of industrial emissions, particularly of reactive hydrocarbons, is critical to effectively address the rapid ozone formation and the consequent high levels of ozone in the area. Industrial emissions of hydrocarbons have significant temporal variability as evidenced by various measurements, but they have been assumed to be continuous at constant levels for air quality regulation and photochemical modeling studies. This thesis examines the effect of emission variability from industrial sources on ozone formation in the HoustonGalveston area. Both discrete emission events and variability in continuous emissions are examined; new air quality modeling tools have been developed to perform these analyses. Also, this thesis evaluates the impact of emission variability on the effectiveness of emission control strategies in the Houston-Galveston area. Overall, the results indicate that industrial emission variability plays a substantial role in ozone formation and that controlling emission variability can be effective in ozone reduction. These results suggest that a quantitative treatment of emission variability should be included in the development of air quality plans for regions with extensive industrial activity, such as Houston.