Thesis (Ph. D.) -- California Institute of Technology, 2010. / Title from home page (viewed 04/05/10). Advisor and committee chair names found in the thesis' metadata record in the digital repository. Includes bibliographical references.

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Thesis (Ph.D.)--University of Iowa, 2006. / Supervisor: Alec B. Scranton. Includes bibliographical references (leaves 145-147).

A dissertation submitted to the Faculty of Science, University of the Witwatersrand in partial fulfilment of the requirement for the degree Master of Science (M.Sc.) in Chemistry. Johannesburg, 31 October 2017. / Nanotechnology has been instrumental in finding strategies of combating some of the world’s grand challenges. Water scarcity and the growing industrialization have made it an imperative to find ways of cleaning water. Photocatalysis is a promising method for water purification personified by the use of solar energy as well as nanomaterials with tailored properties. Colloidal synthesis has made it possible to synthesize new materials with tailored properties, in particular the single-source precursor method has been found to be a useful method in synthesizing nanomaterials with high purity. In the synthesis of metal chalcogenides, the single-source precursor method has an advantage of the precursor having the desired metal-chalcogenide bond hence eliminating the possible formation of side products particularly metal oxides. Herein, acylthiourea (ATU) and thiourea (TU) zinc complexes were used as precursors for the synthesis of ZnS nanoparticles. Bis(N,N-diethyl-N’-benzoylthiourea)Zn(II) [Zn(ATU)2] and bis(diaminomethylthio)Zn(II) chloride [Zn(TU)2Cl2] complexes were synthesized using a conventional method and characterized with elemental analysis, 1H NMR , 2D NMR, COSY, FTIR, mass spectrometry and X-Ray crystallography. The resultant precursors, Zn(ATU)2 and Zn(TU)2Cl2 complexes were then thermolyzed to yield ZnS nanocrystals and characterized fully. Reaction parameters that included the synthetic time, temperature, concentration and capping agents were optimized for each single-source precursor in an attempt to control the nanoparticles yielded hence their properties. Time and temperature studies generally demonstrated the most pronounced effect and with an increase, they showed increasing particle sizes through the Ostwald ripening effect. Also visible from the TEM was that the temperature had an effect on the morphology of the nanoparticles. Increasing the precursor concentration resulted in the agglomeration of nanoparticles, while using different capping agents yielded similar nanoparticles with different degrees of agglomeration. Evident from the results the ATU precursor behaved similar to the TU precursor and generally the particles obtained from the two precursors regardless of the reaction condition were very small. Preliminary investigations into the use of the synthesized nanoparticles obtained from the two precursors revealed potential in photocatalytic degradation of Rhodamine B (RhB) dye in water. While smaller particles were obtained from the synthesized nanoparticles, the degradation efficiencies were lower than the commercial ZnO and TiO2. This is due to the presence of the long-chained capping agents on the synthesized particles blocking the interaction of the core ZnS and the light. / LG2018

published_or_final_version / abstract / Mechanical Engineering / Master / Master of Philosophy

No description available.

Li, Chuanhao. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

by Chan Cho-Yin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 161-173). / Text in English; abstracts in English and Chinese. / by Chan Cho-Yin. / Acknowledgements --- p.i / Abstracts --- p.ii / Table of Contents --- p.vi / List of Figures --- p.xii / List of Plates --- p.xv / List of Tables --- p.xvi / Abbreviations --- p.xix / Equations --- p.1 / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Atrazine --- p.1 / Chapter 1.1.1 --- Characteristics of atrazine --- p.1 / Chapter 1.1.2 --- Use of atrazine --- p.7 / Chapter 1.1.3 --- Inhibitory mechanisms --- p.7 / Chapter 1.1.4 --- Global annual consumption --- p.7 / Chapter 1.1.5 --- Environmental fate --- p.8 / Chapter 1.1.5.1 --- Major intermediates --- p.10 / Chapter 1.1.6 --- Ecotoxicity --- p.10 / Chapter 1.1.6.1 --- Toxicity towards microorganisms --- p.10 / Chapter 1.1.6.2 --- Toxicity towards invertebrates --- p.12 / Chapter 1.1.6.3 --- Toxicity towards vertebrates --- p.15 / Chapter 1.1.7 --- Environmental regulations --- p.16 / Chapter 1.2 --- Treatments of atrazine --- p.16 / Chapter 1.2.1 --- Physical treatments --- p.16 / Chapter 1.2.2 --- Chemical treatments --- p.18 / Chapter 1.2.3 --- Advanced Oxidation Processes (AOPs) --- p.19 / Chapter 1.2.4 --- Photocatalytic Oxidation (PCO) --- p.21 / Chapter 1.2.4.1 --- Cyanuric acid --- p.26 / Chapter 1.2.5 --- Biological treatments --- p.33 / Chapter 1.2.6 --- Integration of treatment methods --- p.36 / Chapter 2 --- Objectives --- p.38 / Chapter 3 --- Materials and methods --- p.39 / Chapter 3.1 --- Photocatalytic oxidation (PCO) reaction --- p.39 / Chapter 3.1.1 --- Chemical reagents --- p.39 / Chapter 3.1.2 --- Photocatalytic reactor --- p.39 / Chapter 3.1.3 --- Determination of atrazine --- p.43 / Chapter 3.1.4 --- Optimization of PCO reactions --- p.43 / Chapter 3.1.4.1 --- Effect of initial hydrogen peroxide concentration --- p.49 / Chapter 3.1.4.2 --- Effect of titanium dioxide concentration --- p.49 / Chapter 3.1.4.3 --- Effect of initial pH --- p.50 / Chapter 3.1.4.4 --- Effect of UV intensities --- p.50 / Chapter 3.1.4.5 --- Internal control of parameters --- p.50 / Chapter 3.1.4.6 --- Combination study of parameters: part one --- p.50 / Chapter 3.1.4.7 --- Combination study of parameters: part two --- p.50 / Chapter 3.1.5 --- Detection methods of atrazine degradation intermediates/products --- p.51 / Chapter 3.1.5.1 --- Gas chromatography-mass spectrometry --- p.51 / Chapter 3.1.5.2 --- High performance liquid chromatography --- p.51 / Chapter 3.1.6 --- Investigation of PCO treated solution --- p.54 / Chapter 3.1.6.1 --- Total organic carbon content --- p.54 / Chapter 3.1.6.2 --- Anions content --- p.54 / Chapter 3.1.6.3 --- pH --- p.56 / Chapter 3.1.6.4 --- Hydrogen peroxide content --- p.56 / Chapter 3.1.6.5 --- Toxicity --- p.56 / Chapter 3.1.6.5.1 --- Microtox® test --- p.56 / Chapter 3.1.6.5.2 --- Amphipod survival test --- p.57 / Chapter 3.2 --- Biodegradation reaction --- p.61 / Chapter 3.2.1 --- Chemical reagents --- p.61 / Chapter 3.2.2 --- Sampling --- p.62 / Chapter 3.2.3 --- Enrichment --- p.62 / Chapter 3.2.4 --- Isolation --- p.65 / Chapter 3.2.5 --- Purification --- p.65 / Chapter 3.2.6 --- Identification of bacterial strain --- p.65 / Chapter 3.2.6.1 --- Gram staining --- p.66 / Chapter 3.2.6.2 --- Catalase and oxidase tests --- p.66 / Chapter 3.2.6.3 --- Sherlock Microbial Identification System (MIDI) --- p.66 / Chapter 3.2.6.4 --- Biolog MicroLog´ёØ system (Biolog) --- p.67 / Chapter 3.2.7 --- Determination of cyanuric acid --- p.67 / Chapter 3.2.8 --- Selection of cyanuric acid degrading bacteria --- p.67 / Chapter 3.2.9 --- Optimization of reaction conditions --- p.67 / Chapter 3.2.9.1 --- Starting medium --- p.68 / Chapter 3.2.9.2 --- Effect of temperatures --- p.68 / Chapter 3.2.9.3 --- Effect of initial pH --- p.69 / Chapter 3.2.9.4 --- Effect of agitation rates --- p.69 / Chapter 3.2.9.5 --- Effect of initial cyanuric acid and glucose concentrations --- p.70 / Chapter 3.2.9.6 --- Investigation of biodegraded solution --- p.70 / Chapter 3.2.9.6.1 --- Glucose content --- p.70 / Chapter 3.2.9.6.2 --- Biodegradation metabolite(s) of cyanuric acid --- p.70 / Chapter 3.3 --- Integration of photocatalytic oxidation and biodegradation --- p.71 / Chapter 4 --- Results --- p.72 / Chapter 4.1 --- Photocatalytic oxidation (PCO) reaction --- p.72 / Chapter 4.1.1 --- Determination of atrazine --- p.72 / Chapter 4.1.2 --- Effect of aeration and mixing --- p.72 / Chapter 4.1.3 --- Effect of initial hydrogen peroxide concentrations --- p.72 / Chapter 4.1.4 --- Effect of titanium dioxide concentrations --- p.78 / Chapter 4.1.5 --- Effect of initial pH --- p.78 / Chapter 4.1.6 --- Effect of UV intensities --- p.78 / Chapter 4.1.7 --- Effect of different internal controls --- p.85 / Chapter 4.1.8 --- "Combination of UV intensities, initial hydrogen peroxide and titanium dioxide concentrations" --- p.85 / Chapter 4.1.9 --- "Combination of initial pH, atrazine concentrations and UV intensities" --- p.94 / Chapter 4.1.10 --- Degradation products detected by GC/MS --- p.94 / Chapter 4.1.11 --- Degradation products detected by HPLC --- p.94 / Chapter 4.1.12 --- Total organic carbon removal --- p.104 / Chapter 4.1.13 --- Anions content --- p.104 / Chapter 4.1.14 --- Solution pH --- p.104 / Chapter 4.1.15 --- Hydrogen peroxide content --- p.108 / Chapter 4.1.16 --- Microtox® test --- p.108 / Chapter 4.1.17 --- Amphipod survival test --- p.114 / Chapter 4.2 --- Biodegradation reaction --- p.118 / Chapter 4.2.1 --- Isolation of bacterial colonies --- p.118 / Chapter 4.2.2 --- Identification and characterization of the isolated bacteria --- p.118 / Chapter 4.2.3 --- Selection of cyanuric acid degrading species --- p.118 / Chapter 4.2.4 --- Effect of temperatures --- p.128 / Chapter 4.2.5 --- Effect of initial pH --- p.128 / Chapter 4.2.6 --- Effect of agitation rates --- p.128 / Chapter 4.2.7 --- Effect of cyanuric acid and glucose concentrations --- p.132 / Chapter 4.2.8 --- Glucose content --- p.132 / Chapter 4.2.9 --- Biodegradation metabolites of cyanuric acid --- p.132 / Chapter 4.2.10 --- Proposed pathway of atrazine degradation by biodegradation enhanced by PCO --- p.138 / Chapter 4.3 --- Integration of photocatalytic oxidation and biodegradation --- p.138 / Chapter 5 --- Discussion --- p.141 / Chapter 5.1 --- Photocatalytic oxidation (PCO) reaction --- p.141 / Chapter 5.1.1 --- Determination of atrazine --- p.141 / Chapter 5.1.2 --- Effect of aeration and mixing --- p.141 / Chapter 5.1.3 --- Effect of initial hydrogen peroxide concentrations --- p.141 / Chapter 5.1.4 --- Effect of titanium dioxide concentrations --- p.143 / Chapter 5.1.5 --- Effect of initial pH --- p.143 / Chapter 5.1.6 --- Effect of UV intensities --- p.144 / Chapter 5.1.7 --- Effect of different internal controls --- p.145 / Chapter 5.1.8 --- "Combination of UV intensities, initial hydrogen peroxide and titanium dioxide concentrations" --- p.145 / Chapter 5.1.9 --- "Combination of initial pH, atrazine concentrations and UV intensities" --- p.146 / Chapter 5.1.10 --- Degradation products detected by GC/MS --- p.146 / Chapter 5.1.11 --- Degradation products detected by HPLC --- p.147 / Chapter 5.1.12 --- Total organic carbon removal --- p.147 / Chapter 5.1.13 --- Anions content --- p.148 / Chapter 5.1.14 --- Solution pH --- p.149 / Chapter 5.1.15 --- Hydrogen peroxide content --- p.149 / Chapter 5.1.16 --- Microtox® test --- p.149 / Chapter 5.1.17 --- Amphipod survival test --- p.150 / Chapter 5.2 --- Biodegradation reaction --- p.151 / Chapter 5.2.1 --- Isolation of bacterial colonies --- p.151 / Chapter 5.2.2 --- Identification and characterization of the isolated bacteria --- p.151 / Chapter 5.2.3 --- Selection of cyanuric acid degrading species --- p.152 / Chapter 5.2.4 --- Effect of temperatures --- p.152 / Chapter 5.2.5 --- Effect of initial pH --- p.153 / Chapter 5.2.6 --- Effect of agitation rates --- p.153 / Chapter 5.2.7 --- Effect of cyanuric acid and glucose concentrations --- p.154 / Chapter 5.2.8 --- Glucose content --- p.154 / Chapter 5.2.9 --- Biodegradation metabolites of cyanuric acid --- p.155 / Chapter 5.2.10 --- Proposed degradation pathway of atrazine by biodegradation enhanced by PCO --- p.155 / Chapter 5.3 --- Integration of photocatalytic oxidation and biodegradation --- p.155 / Chapter 6 --- Conclusions --- p.159 / Chapter 7 --- References --- p.161 / Appendix1 --- p.174 / Appendix2 --- p.175