Este trabalho visa o estudo de processos de degradação fotocatalítica e fotoeletrocatalítica de corantes sobre dióxido de titânio. O enfoque está voltado ao uso de técnicas espectroscópicas, com especial destaque para o desenvolvimento de metodologias de espectroscopia vibracional Raman intensificada. Nesse sentido, tem-se em vista a investigação dos mecanismos envolvidos nos processos de fotodegradação e fotoeletrodegradação de corantes, através da identificação de intermediários e produtos de processos de degradação por técnicas de espectroscopia eletrônica e Raman. Os estudos de fotocatálise são também expandidos para ambientes eletroquímicos. Nos chamados processos fotoeletrocatalíticos, a combinação de processos eletroquímicos e fotoquímicos mostra-se bastante promissora para a degradação de poluentes orgânicos. O primeiro desafio no desenvolvimento desse trabalho foi construir o fotorreator adequado que permitisse a obtenção de amostras para serem analisadas por espectroscopia Raman, e apresentasse boa eficiência nos processos de fotocatálise e também fotoeletrocatálise. Encontrado o fotorreator adequado, investigamos o comportamento cinético dos processos foto(eletro)degradação de corantes, buscando verificar a dependência com o potencial eletroquímico aplicado, o efeito do eletrólito suporte, e a identificação de intermediários formados durante o processo de degradação. Analisamos também aspectos relacionados aos mecanismos de adsorção de corantes sobre a superfície do dióxido de titânio. Tais aspectos podem ser de significativa relevância no desenvolvimento de técnicas eficazes para o tratamento de poluentes orgânicos. Nossos estudos estiveram principalmente centrados em dois corantes: o azocorante verde de Janus e o corante antraquinônico alizarina vermelha S. Os resultados obtidos nos estudos da cinética dos processos fotoeletrocatalíticos sugerem que o efeito do potencial aplicado depende de maneira significativa da natureza química do corante. Observou-se uma tendência dos processos fotoeletrocatalíticos serem mais eficientes na remoção da coloração da solução corante do verde de Janus quando comparados aos fotocatalíticos. Tal tendência não foi observada para o corante alizarina vermelha S. Essa diferença de comportamento pôde ser relacionada à natureza das interações específicas de entre cada corante e a superfície do catalisador. Nossos estudos a respeito dos mecanismos envolvidos nos processos de degradação do verde de Janus revelaram que as primeiras etapas dos processos de fotodegradação e fotoeletrodegradação seguem mecanismos diferentes. Os resultados obtidos mostram que a degradação do verde de Janus em suspensão de TiO2 envolve entre suas etapas modificações na ligação azo desse corante (N=N), resultando na formação de um composto intermediário derivado da fenossafranina. No processo fotoeletrocatalítico, por outro lado, observa-se um mecanismo diferenciado o qual não envolve em suas etapas iniciais a quebra da ligação azo do corante / This work focuses on the study of photocatalytic and photoelectrocatalytic degradation processes of dyes over titanium dioxide. The main approach is based on the use of spectroscopic techniques, with special emphasis to methodologies based on surface-enhanced Raman spectroscopy. Within this context, the mechanisms involved in the photodegradation and photoelectrodegradation of dyes are investigated by the identification of degradation intermediates through vibrational and electronic spectroscopies. In the so-called photoelectrocatalytic processes, the combination of electrochemical and photochemical processes is an interesting and promising approach for the degradation of a wide variety of organic pollutants. The first step in the development of the present work was to build a photo reactor that allowed the analysis of samples through Raman spectroscopy and presented a good efficiency for both photocatalytic and photoelectrocatalytic processes. We then investigated the kinetic behavior of the photo(electro)degradation of dyes in order to verify the dependence upon the electrochemical applied potential, the effect of the supporting electrolyte, and the identification of intermediate products formed during the degradation process. We also analyzed aspects related to the adsorption mechanisms of the dyes on the titanium dioxide surface. Such aspects can be relevant to the understanding and to the development of efficient techniques for the remediation of organic pollutants. Our studies focused mainly on two dyes: the azo dye Janus green and the anthraquinonic dye alizarin red S. The results obtained in the kinetic study of the photoelectrocatalytic processes suggest that the effect of the applied electrochemical potential strongly depends on the chemical nature of the investigated dye. We have observed that the decolorization of Janus green is favored for photoelectrocatalytic process as compared to the photocatalytic degradation. Such behavior was not observed for the anthraquinonic dye alizarin red S. This difference was related to the nature of the specific interactions between each dye and the catalyst surface. Our studies regarding the mechanisms of degradation revealed that the first steps of the photocatalytic and photoelectrocatalytic processes of Janus green followed different routes. The obtained results indicate that the degradation of Janus green in aqueous TiO2 suspension involves changes in the azo bond (N=N), resulting in the formation of an intermediate compound a derived from the phenosafranine structure, whereas for the photoelectrocatalytic process there are evidences of a different mechanism that does not involve the cleavage of the azo bond.

by Cheung Kit Hing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 175-199). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstracts --- p.ii / Table of Contents --- p.vi / List of Figures --- p.xviii / List of Plates --- p.xxii / List of Tables --- p.xxiii / Abbreviations --- p.xxv / Equations --- p.xxviii / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- The chemistry of azo dyes --- p.1 / Chapter 1.2 --- Azo dyes classification --- p.2 / Chapter 1.3 --- Environmental concerns and toxicity --- p.4 / Chapter 1.3.1 --- Toxicity of azo dyes --- p.5 / Chapter 1.3.2 --- Carcinogenicity --- p.5 / Chapter 1.3.3 --- Ecotoxicity --- p.11 / Chapter 1.3.3.1 --- Toxicity to microorganisms --- p.12 / Chapter 1.3.3.2 --- Toxicity towards vertebrates --- p.13 / Chapter 1.4 --- Treatment of azo dyes --- p.13 / Chapter 1.4.1 --- Physical treatment --- p.14 / Chapter 1.4.1.1 --- Adsorption --- p.14 / Chapter 1.4.1.2 --- Membrane technology --- p.15 / Chapter 1.4.2 --- Chemical treatments --- p.15 / Chapter 1.4.2.1 --- Chlorination --- p.16 / Chapter 1.4.2.2 --- Fenton's reaction --- p.16 / Chapter 1.4.2.3 --- Ozonation --- p.16 / Chapter 1.4.2.4 --- Coagulation --- p.17 / Chapter 1.4.3 --- Biological treatments --- p.17 / Chapter 1.4.3.1 --- Activated sludge process --- p.18 / Chapter 1.4.3.2 --- Biodegradation --- p.18 / Chapter 1.4.3.3 --- Biosorption --- p.21 / Chapter 1.4.3.3.1 --- Modeling of sorption --- p.24 / Chapter 1.4.3.3.1.1 --- Langmuir sorption model --- p.24 / Chapter 1.4.3.3.1.2 --- Freundlich sorption model --- p.25 / Chapter 1.4.4 --- Advanced oxidation processes --- p.25 / Chapter 1.4.4.1 --- Photocatalytic oxidation --- p.26 / Chapter 1.4.4.2 --- Titanium dioxide (TiO2) --- p.26 / Chapter 1.4.4.3 --- Mechanism of photocatalytic oxidation using photocatalyst TiO2 --- p.28 / Chapter 1.4.4.4 --- Photocatalytic oxidation of s-triazine containing compounds --- p.30 / Chapter 1.4.4.5 --- Photocatalytic oxidation of Procion Red MX-5B --- p.31 / Chapter 1.4.4.6 --- Cyanuric acid --- p.32 / Chapter 1.4.4.6.1 --- Application --- p.32 / Chapter 1.4.4.6.2 --- Toxicity --- p.32 / Chapter 1.4.4.6.3 --- Photocatalytic oxidation resistance --- p.34 / Chapter 1.4.4.6.4 --- Biodegradation --- p.35 / Chapter 1.4.4.7 --- Enhancement of photocatalytic oxidation by using sorbent immobilized with TiO2 --- p.35 / Chapter 1.4.4.7.1 --- Sorption --- p.35 / Chapter 1.4.4.7.2 --- Immobilization of TiO2 --- p.37 / Chapter 1.4.8 --- Integration of treatment methods --- p.39 / Chapter 2. --- Objectives --- p.41 / Chapter 3. --- Materials and methods --- p.42 / Chapter 3.1. --- Sorption --- p.42 / Chapter 3.1.1 --- Chemical reagents --- p.42 / Chapter 3.1.2 --- Determination of Procion Red MX-5B --- p.42 / Chapter 3.1.3 --- Sampling --- p.44 / Chapter 3.1.4 --- Isolation of Procion Red MX-5B-sorbing bacteria --- p.44 / Chapter 3.1.5 --- Screening of Procion Red MX-5B sorption ability --- p.44 / Chapter 3.1.6 --- Identification of isolated bacterium --- p.46 / Chapter 3.1.7 --- Optimization of cell yield and sorption capacity --- p.47 / Chapter 3.1.7.1 --- Preparation of cell culture of Vibrio sp. --- p.47 / Chapter 3.1.7.2 --- Growth phase --- p.47 / Chapter 3.1.7.2.1 --- Growth curve --- p.47 / Chapter 3.1.7.2.2 --- Dye sorption capacity --- p.47 / Chapter 3.1.7.3 --- Initial pH --- p.48 / Chapter 3.1.7.3.1 --- Growth curve --- p.48 / Chapter 3.1.7.3.2 --- Dye sorption capacity --- p.48 / Chapter 3.1.7.4 --- Temperature --- p.49 / Chapter 3.1.7.4.1 --- Growth curve --- p.49 / Chapter 3.1.7.4.2 --- Dye sorption capacity --- p.49 / Chapter 3.1.7.5 --- Glucose concentrations --- p.49 / Chapter 3.1.7.5.1 --- Growth curve --- p.49 / Chapter 3.1.7.5.2 --- Dye sorption capacity --- p.50 / Chapter 3.1.8 --- Optimization of sorption process --- p.50 / Chapter 3.1.8.1 --- Preparation of sorbent --- p.50 / Chapter 3.1.8.2 --- Dry weight of sorbent --- p.50 / Chapter 3.1.8.3 --- Temperature --- p.50 / Chapter 3.1.8.4 --- Agitation rate --- p.50 / Chapter 3.1.8.5 --- Salinity --- p.51 / Chapter 3.1.8.6 --- Initial pH --- p.51 / Chapter 3.1.8.7 --- Concentration of Procion Red MX-5B --- p.51 / Chapter 3.1.8.8 --- Combination study of salinity and initial pH --- p.51 / Chapter 3.2. --- Photocatalytic oxidation reaction --- p.52 / Chapter 3.2.1 --- Chemical reagents --- p.52 / Chapter 3.2.2 --- Photocatalytic reactor --- p.52 / Chapter 3.2.3 --- Optimization of sorption and photocatalytic oxidation reactions using biomass of Vibrio sp.immobilized in calcium alginate beads --- p.54 / Chapter 3.2.3.1 --- Effect of dry weight of immobilized cells of Vibrio sp. --- p.54 / Chapter 3.2.3.1.1 --- Sorption --- p.55 / Chapter 3.2.3.1.2 --- Photocatalytic oxidation --- p.56 / Chapter 3.2.3.2 --- Effect of UV intensities --- p.57 / Chapter 3.2.3.3 --- Effect of TiO2 concentrations --- p.57 / Chapter 3.2.3.3.1 --- Sorption --- p.57 / Chapter 3.2.3.3.2 --- Photocatalytic oxidation --- p.57 / Chapter 3.2.3.4 --- Effect of H202 concentrations --- p.57 / Chapter 3.2.3.5 --- Effect of the number of beads --- p.58 / Chapter 3.2.3.5.1 --- Sorption --- p.58 / Chapter 3.2.3.5.2 --- Photocatalytic oxidation --- p.58 / Chapter 3.2.3.6 --- Effect of initial pH with and without the addition of H2O2 --- p.58 / Chapter 3.2.3.7 --- Control experiments for photocatalytic oxidation of Procion Red MX-5B --- p.59 / Chapter 3.2.3.8 --- Combinational study of UV intensities and H2O2 concentrations --- p.59 / Chapter 3.2.3.9 --- Photocatalytic oxidation of Procion Red MX-5B under optimal conditions --- p.59 / Chapter 3.2.3.10 --- "Sorption isotherms of calcium alginate beads immobilized with 70 mg Vibrio sp. and 5,000 mg/L TiO2" --- p.59 / Chapter 3.3 --- Biodegradation --- p.60 / Chapter 3.3.1 --- Chemical reagents --- p.60 / Chapter 3.3.2 --- Sampling --- p.60 / Chapter 3.3.3 --- Enrichment --- p.60 / Chapter 3.3.4 --- Isolation of cyanuric acid-utilizing bacteria --- p.61 / Chapter 3.3.5 --- Determination of cyanuric acid --- p.61 / Chapter 3.3.6 --- Screening of Procion Red MX-5B sorption ability --- p.61 / Chapter 3.3.7 --- Screening of cyanuric acid-utilizing ability --- p.61 / Chapter 3.3.8 --- Bacterial identification --- p.63 / Chapter 3.3.9 --- Growth and cyanuric acid removal efficiency of the selected bacterium --- p.63 / Chapter 3.3.10 --- Optimization of reaction conditions --- p.64 / Chapter 3.3.10.1 --- Effect of salinity --- p.64 / Chapter 3.3.10.2 --- Effect of cyanuric acid concentrations --- p.65 / Chapter 3.3.10.3 --- Effect of temperature --- p.65 / Chapter 3.3.10.4 --- Effect of agitation rate --- p.65 / Chapter 3.3.10.5 --- Effect of initial pH --- p.66 / Chapter 3.3.10.6 --- Effect of initial glucose concentration --- p.66 / Chapter 3.3.10.7 --- Combinational study of glucose and cyanuric acid concentrations --- p.66 / Chapter 3.4 --- Detection of cyanuric acid formed in photocatalytic oxidation reaction --- p.66 / Chapter 3.5 --- "Integration of sorption, photocatalytic oxidation and biodegradation" --- p.67 / Chapter 4. --- Results --- p.68 / Chapter 4.1. --- Sorption --- p.68 / Chapter 4.1.1 --- Determination of Procion Red MX-5B --- p.68 / Chapter 4.1.2 --- Isolation of Procion Red MX-5B-sorbing bacteria --- p.68 / Chapter 4.1.3 --- Screening of Procion Red MX-5B sorption ability --- p.68 / Chapter 4.1.4 --- Identification of isolated bacterium --- p.72 / Chapter 4.1.5 --- Optimization of cell yield and sorption capacity --- p.72 / Chapter 4.1.5.1 --- Growth phase --- p.72 / Chapter 4.1.5.1.1 --- Growth curve --- p.72 / Chapter 4.1.5.1.2 --- Dye sorption capacity --- p.72 / Chapter 4.1.5.2 --- Initial pH --- p.75 / Chapter 4.1.5.2.1 --- Growth curve --- p.75 / Chapter 4.1.5.2.2 --- Dye sorption capacity --- p.75 / Chapter 4.1.5.3 --- Temperature --- p.75 / Chapter 4.1.5.3.1 --- Growth curve --- p.75 / Chapter 4.1.5.3.2 --- Dye sorption capacity --- p.79 / Chapter 4.1.5.4 --- Glucose concentrations --- p.79 / Chapter 4.1.5.4.1 --- Growth curve --- p.79 / Chapter 4.1.5.4.2 --- Dye sorption capacity --- p.79 / Chapter 4.1.6 --- Optimization of sorption process --- p.82 / Chapter 4.1.6.1 --- Dry weight of sorbent --- p.82 / Chapter 4.1.6.2 --- Temperature --- p.82 / Chapter 4.1.6.3 --- Agitation rate --- p.86 / Chapter 4.1.6.4 --- Salinity --- p.86 / Chapter 4.1.6.5 --- Initial pH --- p.86 / Chapter 4.1.6.6 --- Concentration of Procion Red MX-5B --- p.90 / Chapter 4.1.6.7 --- Combination study of salinity and initial pH --- p.90 / Chapter 4.2. --- Photocatalytic oxidation reaction --- p.94 / Chapter 4.2.1 --- Effect of dry weight of immobilized cells of Vibrio sp. --- p.94 / Chapter 4.2.1.1 --- Sorption --- p.94 / Chapter 4.2.1.2 --- Photocatalytic oxidation --- p.96 / Chapter 4.2.2 --- Effect of UV intensities --- p.96 / Chapter 4.2.3 --- Effect of TiO2 concentrations --- p.96 / Chapter 4.2.3.1 --- Sorption --- p.96 / Chapter 4.2.3.2 --- Photocatalytic oxidation --- p.101 / Chapter 4.2.4 --- Effect of H2O2 concentrations --- p.101 / Chapter 4.2.5 --- Effect of the number of beads --- p.101 / Chapter 4.2.5.1 --- Sorption --- p.105 / Chapter 4.2.5.2 --- Photocatalytic oxidation --- p.105 / Chapter 4.2.6 --- Effect of initial pH with and without the addition of --- p.105 / Chapter 4.2.7 --- Control experiments for photocatalytic oxidation of Procion Red MX-5B --- p.109 / Chapter 4.2.8 --- Combinational study of UV intensities and H202 concentrations --- p.112 / Chapter 4.2.9 --- Photocatalytic oxidation of Procion Red MX-5B under optimal conditions --- p.112 / Chapter 4.2.10 --- "Sorption isotherms of calcium alginate beads immobilized with 70 mg Vibrio sp. and 5,000 mg/L Ti02" --- p.112 / Chapter 4.3 --- Biodegradation --- p.116 / Chapter 4.3.1 --- Isolation of cyanuric acid-utilizing bacteria --- p.116 / Chapter 4.3.2 --- Determination of cyanuric acid --- p.116 / Chapter 4.3.3 --- Screening of Procion Red MX-5B sorption ability --- p.116 / Chapter 4.3.4 --- Screening of cyanuric acid-utilizing ability --- p.116 / Chapter 4.3.5 --- Bacterial identification --- p.118 / Chapter 4.3.6 --- Growth and cyanuric acid removal efficiency of the selected bacterium --- p.118 / Chapter 4.3.7 --- Optimization of reaction conditions --- p.122 / Chapter 4.3.7.1 --- Effect of salinity --- p.122 / Chapter 4.3.7.2 --- Effect of cyanuric acid concentrations --- p.122 / Chapter 4.3.7.3 --- Effect of temperature --- p.126 / Chapter 4.3.7.4 --- Effect of agitation rate --- p.126 / Chapter 4.3.7.5 --- Effect of initial pH --- p.132 / Chapter 4.3.7.6 --- Effect of initial glucose concentration --- p.132 / Chapter 4.3.7.7 --- Combinational study of glucose and cyanuric acid concentrations --- p.132 / Chapter 4.4 --- Detection of cyanuric acid formed in photocatalytic oxidation reaction --- p.137 / Chapter 4.5 --- "Integration of sorption, photocatalytic oxidation and biodegradation" --- p.137 / Chapter 5. --- Discussion --- p.141 / Chapter 5.1 --- Sorption --- p.141 / Chapter 5.1.1 --- Isolation of Procion Red MX-5B-sorbing bacteria --- p.141 / Chapter 5.1.2 --- Screening of Procion Red MX-5B sorption ability --- p.141 / Chapter 5.1.3 --- Identification of isolated bacterium --- p.141 / Chapter 5.1.4 --- Optimization of cell yield and sorption capacity --- p.142 / Chapter 5.1.4.1 --- Growth phase --- p.142 / Chapter 5.1.4.1.1 --- Growth curve --- p.142 / Chapter 5.1.4.1.2 --- Dye sorption capacity --- p.143 / Chapter 5.1.4.2 --- Initial pH --- p.146 / Chapter 5.1.4.2.1 --- Growth curve --- p.146 / Chapter 5.1.4.2.2 --- Dye sorption capacity --- p.146 / Chapter 5.1.4.3 --- Temperature --- p.146 / Chapter 5.1.4.3.1 --- Growth curve --- p.146 / Chapter 5.1.4.3.2 --- Dye sorption capacity --- p.147 / Chapter 5.1.4.4 --- Glucose concentrations --- p.147 / Chapter 5.1.4.4.1 --- Growth curve --- p.147 / Chapter 5.1.4.4.2 --- Dye sorption capacity --- p.147 / Chapter 5.1.5 --- Optimization of sorption process --- p.148 / Chapter 5.1.5.1 --- Dry weight of sorbent --- p.148 / Chapter 5.1.5.2 --- Temperature --- p.148 / Chapter 5.1.5.3 --- Agitation rate --- p.149 / Chapter 5.1.5.4 --- Salinity --- p.149 / Chapter 5.1.5.5 --- Initial pH --- p.150 / Chapter 5.1.5.6 --- Concentration of Procion Red MX-5B (MX-5B) --- p.152 / Chapter 5.1.5.7 --- Combination study of salinity and initial pH --- p.153 / Chapter 5.2. --- Photocatalytic oxidation reaction --- p.153 / Chapter 5.2.1 --- Effect of immobilized cells of Vibrio sp. --- p.153 / Chapter 5.2.1.1 --- Sorption --- p.153 / Chapter 5.2.1.2 --- Photocatalytic oxidation --- p.154 / Chapter 5.2.2 --- Effect of UV intensities --- p.155 / Chapter 5.2.3 --- Effect of TiO2 concentrations --- p.155 / Chapter 5.2.3.1 --- Sorption --- p.155 / Chapter 5.2.3.2 --- Photocatalytic oxidation --- p.156 / Chapter 5.2.4 --- Effect of H2O2 concentrations --- p.156 / Chapter 5.2.5 --- Effect of the number of beads --- p.157 / Chapter 5.2.5.1 --- Sorption --- p.157 / Chapter 5.2.5.2 --- Photocatalytic oxidation --- p.158 / Chapter 5.2.6 --- Effect of initial pH with and without the addition of --- p.158 / Chapter 5.2.7 --- Control experiments for photocatalytic oxidation of Procion Red MX-5B --- p.160 / Chapter 5.2.8 --- Combinational study of UV intensities and H202 concentrations --- p.161 / Chapter 5.2.9 --- Photocatalytic oxidation of Procion Red MX-5B under optimal conditions --- p.161 / Chapter 5.2.10 --- "Sorption isotherms of calcium alginate beads immobilized with 70 mg Vibrio sp. and 5,000 mg/L Ti02" --- p.161 / Chapter 5.3 --- Biodegradation --- p.162 / Chapter 5.3.1 --- Isolation of cyanuric acid-utilizing bacteria --- p.162 / Chapter 5.3.2 --- Determination of cyanuric acid --- p.163 / Chapter 5.3.3 --- Screening of Procion Red MX-5B sorption ability --- p.163 / Chapter 5.3.4 --- Screening of cyanuric acid-utilizing ability --- p.163 / Chapter 5.3.5 --- Bacterial identification --- p.163 / Chapter 5.3.6 --- Growth and cyanuric acid removal efficiency of the selected bacterium --- p.164 / Chapter 5.3.7 --- Optimization of reaction conditions --- p.165 / Chapter 5.3.7.1 --- Effect of salinity --- p.165 / Chapter 5.3.7.2 --- Effect of cyanuric acid concentration --- p.165 / Chapter 5.3.7.3 --- Effect of temperature --- p.166 / Chapter 5.3.7.4 --- Effect of agitation rate --- p.167 / Chapter 5.3.7.5 --- Effect of initial pH --- p.167 / Chapter 5.3.7.6 --- Effect of initial glucose concentration --- p.167 / Chapter 5.3.7.7 --- Combinational study of glucose and cyanuric acid concentrations --- p.168 / Chapter 5.4 --- Detection of cyanuric acid formed in photocatalytic oxidation reaction --- p.170 / Chapter 5.5 --- "Integration of sorption, photocatalytic oxidation and biodegradation" --- p.171 / Chapter 5.6 --- Recommendations --- p.171 / Chapter 6. --- Conclusions --- p.173 / Chapter 7. --- References --- p.175 / Appendix --- p.200

Kwong Tsz Yan Alex. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 77-84). / Abstracts in English and Chinese. / Abstract --- p.i / Declaration --- p.iii / Acknowledgement --- p.iv / Table of contents --- p.v / List of tables --- p.ix / List of figures --- p.x / Chapter Chapter One : --- Introduction --- p.1 / Chapter 1.1 --- The outbreak of SARS --- p.1 / Chapter 1.2 --- Characteristics of triclosan --- p.2 / Chapter 1.3 --- Environmental fate of triclosan --- p.3 / Chapter 1.4 --- Treatment methods for triclosan --- p.5 / Chapter 1.5 --- Ti02 photocatalysis --- p.6 / Chapter 1.6 --- Addition of hydrogen peroxide to the photocatalytic system --- p.9 / Chapter 1.7 --- Gas chromatography/ ion trap mass spectrometry analysis --- p.10 / Chapter 1.8 --- Scope of work --- p.11 / Chapter Chapter Two : --- Experimental --- p.13 / Chapter 2.1 --- Chemical reagents --- p.13 / Chapter 2.2 --- Photocatalytic experiments --- p.14 / Chapter 2.3 --- "Analysis of 2,8-DCDD and triclosan by GC/ITMS" --- p.15 / Chapter 2.4 --- Optimization of GC/ITMS conditions --- p.17 / Chapter 2.5 --- Analysis of other reaction intermediates by GC/MS (full scan mode) --- p.18 / Chapter 2.6 --- "Analysis of 2,4-dichlorophenol and triclosan by GC/MS (SIM mode)" --- p.20 / Chapter 2.7 --- Effect of hydrogen peroxide concentration on triclosan degradation --- p.20 / Chapter 2.8 --- Determination of total organic carbon (TOC) removal --- p.21 / Chapter 2.9 --- UV-Visible spectrometry --- p.21 / Chapter Chapter Three : --- Results --- p.22 / Chapter 3.1 --- Selection of precursor ions for GC/ITMS analysis --- p.22 / Chapter 3.2 --- Optimization of GC/ITMS conditions --- p.25 / Chapter 3.3 --- "Analysis of 2,8-DCDD and triclosan by GC/ITMS" --- p.27 / Chapter 3.4 --- "Analysis of 2,4-dichlorophenol and triclosan by GC/MS (SIM mode)" --- p.29 / Chapter 3.5 --- "Quantitative measurement of 2,8-DCDD in UV irradiated samples" --- p.31 / Chapter 3.6 --- Photocatalytic oxidation of triclosan by UV at 365nm --- p.33 / Chapter 3.7 --- TOC removal in triclosan degradation --- p.35 / Chapter 3.8 --- Identification of intermediates in photocatalytic oxidation of triclosan --- p.36 / Chapter 3.9 --- Quantitative measurement of the intermediates in photocatalytic oxidation of triclosan --- p.41 / Chapter 3.10 --- Effect of hydrogen peroxide concentration on triclosan degradation --- p.43 / Chapter 3.11 --- Effect of hydrogen peroxide concentration on TOC removal --- p.46 / Chapter 3.12 --- "Effect of hydrogen peroxide concentration on 2,4-dichlorophenol generation during triclosan degradation" --- p.47 / Chapter 3.13 --- "Photocatalytic degradation of 2,4-dichlorophenol" --- p.49 / Chapter 3.14 --- "Identification of intermediates in photocatalytic oxidation of 2,4-dichlorophenol" --- p.50 / Chapter 3.15 --- "Quantitative measurement of the intermediates in photocatalytic oxidation of 2,4-dichlorophenol" --- p.54 / Chapter Chapter Four : --- Discussions --- p.56 / Chapter 4.1 --- "Photochemical conversion of triclosan to 2,8-DCDD" --- p.56 / Chapter 4.2 --- Proposed mechanism of triclosan degradation --- p.57 / Chapter 4.3 --- "Proposed mechanism of 2,4-dichlorophenol degradation" --- p.63 / Chapter 4.4 --- TOC removal in triclosan degradation --- p.65 / Chapter 4.5 --- Effect of hydrogen peroxide concentration on photocatalytic oxidation of triclosan --- p.65 / Chapter 4.6 --- "Adverse environmental and human health effects of 2,8-DCDD" --- p.69 / Chapter 4.7 --- "Adverse environmental and human health effects of 2,4-dichlorophenol" --- p.71 / Chapter 4.8 --- "Discharge limitations for 2,4-dichlorophenol" --- p.73 / Chapter Chapter Five : --- Conclusions --- p.75 / References --- p.77

by chan Cho-Yin. / "November 2005." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 128-142). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Text in English; abstracts in English and Chinese. / by Chan Cho-Yin.

Mesoporous titania molecular-sieve thin films have been modified by incorporating guest species either in the pores or on the walls of the structure. The incorporation was realized with the aid of sonochemical processing. The structure, morphology, texture, optical properties, and stability of the resulting nanostructures were characterized by X-ray diffraction, nitrogen adsorption, UV-vis diffuse reflectance spectroscopy, infrared spectroscopy, photoluminesent spectroscopy, scanning electron microscopy, transmission electron microscopy, thermalgravimetric and differential thermal analyses. The photocatalytic and catalytic properties of the mesoporous TiO2-based nanocomposites were evaluated by photocatalytic degradation of organic pollutants, photo-assisted killing of bacteria/cancer-cells, and catalytic oxidation of carbon monoxide. / The thesis includes seven parts. The first part describes the pore-wall chemistry and photocatalytic activity of mesoporous nanocrystalline TiO 2 molecular sieve films. The ordered mesoporous TiO2 films show better photocatalytic activities than do the conventional sol-gel-derived TiO2 films toward the degradation of volatile organic pollutants. The reasons for the high activities of the mesostructural films are also discussed. The second part of the thesis reports the incorporation of highly dispersed gold nanoparticles in the mesoporous TiO2 films by a sono- and photochemical approach. The gold nanoparticles thus obtained are well-confined and stabilized in the nanopores of the TiO2 film and therefore, the intrinsic agglomeration of gold nanoparticles is prevented. This eliminates the use of potentially catalyst-poisoning organic ligands for stabilization. This method can also be used to prepare ordered mesoporous Pt/TiO2 and Ag/TiO2 nanocomposites with catalytic and photocatalytic functions as described in the third and forth parts of the thesis. In the fifth part, solid superacid molecular sieves are prepared by the wall-functionalization of the TiO2 film by sulfate groups with the aid of sonication. The resulting 3D-ordered mesoporous sulfated TiO2 superacid molecular sieve films are found to be attractive photocatalysts for environmental applications. The sixth part the thesis reported the sonodeposition of poorly dissolved phthalocyanine dyes onto the surface of the TiO2 film. The dye molecules are attached and stabilized in the pores of the film, avoiding the aggregation of the dye molecules, and consequently achieving effective photosensitization of the TiO2 film. The final part of the thesis describes the preparation of hierarchically macro/mesoporous TiO2 nanostructural photocatalysts. The existence of macroporous channels in a mesoporous TiO2 material improves the photoabsorption efficiency and matter-transfer. These enhance the photocatalytic performance of the bimodal porous TiO2 nanocomposites toward degradation organic pollutants in gas-phase. (Abstract shortened by UMI.) / Wang Xinchen. / "July 2005." / Adviser: Jimmy C. Yu. / Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0293. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

O presente trabalho tem o objetivo de investigar a obtenção de hidrogênio a partir de soluções de etanol em água, por fotocatálise, usando-se catalisadores a base de óxido de zinco (ZnO). Nestes estudos foram empregados cinco catalisadores ZnO, sendo um comercial e os demais preparados através de diferentes metodologias encontradas na literatura. Os catalisadores foram caracterizados por área BET, DRX e FRX, e a investigação preliminar da atividade destes catalisadores foi feita através de ensaios de degradação fotocatalítica de rodamina B em reator slurry em batelada, onde foram avaliadas a taxa de reação e a remoção de corante. Os ensaios para a produção fotocatalítica de hidrogênio foram realizados em um reator de quartzo, operado em batelada com catalisador em suspensão e atmosfera inerte de nitrogênio. A solução foi irradiada por uma série de seis lâmpadas compactas de luz negra. Ao longo dos testes, amostras das fases líquida e gasosa foram coletadas e analisadas para identificação do consumo de etanol e produção de hidrogênio usando-se, respectivamente, Carbono Orgânico Total (TOC) e Cromatografia Gasosa (GC). Resultados preliminares mostraram que os catalisadores ZnO comercial e sintetizado (ZnO Merck e ZnO-B) apresentam atividade fotocatalítica e desempenho similares aos do TiO2 para a degradação da rodamina B. Contudo, estes mesmos catalisadores mostraram-se pouco ativos para a produção fotocatalítica de hidrogênio, com desempenho bastante inferior ao do TiO2 nas mesmas condições. Foi possível observar que o maior rendimento em hidrogênio ocorre para baixas concentrações de catalisador (0,05 gL[elevado a potência menos]1) e elevadas concentrações de etanol, sendo pouco dependente do pH. / This work aims to investigate the hydrogen production from ethanol-water solutions through photocatalysis, using zinc oxide catalysts (ZnO). Five ZnO catalysts were employed in this work; one was a commercial catalyst, while the others were prepared according to different methodologies reported in the literature. The catalysts were characterized by BET, XRD and XRF, and the preliminary investigation of their activity was done by photocatalytic degradation of rhodamine B, through the evaluation of the reaction rate and dye removal. Tests for photocatalytic hydrogen production were carried out in a quartz slurry batch reactor under nitrogen, irradiated by a set of six compact UV light bulbs. During the tests, gas and liquid samples were collected and analyzed in order to identify the consumption of ethanol and hydrogen production using, respectively, Total Organic Carbon (TOC) and Gas Chromatograph (GC). Preliminary results showed that the synthesized and commercial ZnO catalysts (ZnO-B and ZnO Merck) present photocatalytic activity and performance similar to TiO2 for the rhodamine B degradation. However, the ZnO catalysts presented lower performance when compared with TiO2 for hydrogen production, under the same conditions. It was observed that the highest hydrogen yield occurs for low concentrations of catalyst (0.05 gL1) and high concentrations of ethanol, being less dependent on pH.

Este trabalho de mestrado descreve a avaliação do emprego do TiO2, obtido por diferentes rotas de sínteses e do TiO2 P25 ambos modificados superficialmente com prata e cobre, como catalisador no processo de fotocátalise heterogênea visando a degradação de fenol e efluentes industriais, especificamente efluentes fenólicos. A deterioração dos recursos hídricos é uma das maiores preocupações da sociedade moderna. Dentre os principais responsáveis pela diminuição sistemática na qualidade dos sistemas aquáticos, destacam-se os compostos orgânicos poluentes presentes em efluentes industriais. Dentre esta vasta gama de compostos, os fenóis mostram-se especialmente deletérios ao meio ambiente, devido a sua elevada toxicidade, tendência a bioacumulação e grandes quantidades em que são gerados pelos mais diversos tipos de atividades produtivas. Este trabalho avaliou a aplicação do TiO2 sintetizado pelos métodos de sol-gel e precipitação homogênea na degradação de fenol e no tratamento de efluentes industriais fenólicos. De um modo geral, após 90 minutos de tratamento estes materiais permitiram uma redução de 90% no teor de fenol e de 30% na concentração de carbono orgânico total. Estes resultados são superiores aos obtidos empregando-se TiO¬2 P25 (material comercial mais utilizado neste tipo de processo). A aplicação destes materiais sintetizados na remediação de uma matriz real complexa (efluente industrial) também mostrou uma melhoria na redução de fenol (cerca de 16%) em comparação ao catalisador comercial. Além da síntese do TiO2, também avaliou-se a modificação da superfície das partículas deste semicondutor com prata e cobre visando mais uma vez um aumento na eficiência do processo de fotodegradação. A deposição de prata ou cobre nas partículas do TiO2 P25 promoveu um aumento na capacidade de redução média de fenol e carbono orgânico deste poluente de 15 e 45%, respectivamente. A modificação superficial do TiO2 sintetizado tanto por sol-gel quanto por precipitação homogênea gerou um aumento médio na eficiência catalítica do semicondutor de 30% na mineralização de fenol e 98% na redução da concentração inicial desta espécie. Aplicando estes catalisadores modificados no tratamento do efluente fenólico houve um aumento na mineralização de 32% e uma redução na concentração inicial de fenol de 98% do efluente fenólico. De maneira geral a síntese do TiO2 e a modificação superficial das partículas do catalisador com prata e cobre mostraram-se bastante promissoras para uma futura aplicação destes materiais na remediação de efluentes fenólicos. / This work describes the evaluation of TiO2, obtained from different synthesis routs and superficially modified with silver and copper, as the catalyst in the heterogeneous photocatalysis process to promote phenol degradation and industrial effluents remediation, specifically phenolic effluents. The deterioration of water resources is one the greatest concerns of modern society. Among many responsible for the systematic decreases in the aquatic systems quality, special attention has been give to the organic pollutant compounds presents in the industrial effluents. Among this wide range compounds, the phenols have been showed many deleterious effect to the environment, especially because their high toxicity, bioaccumulation tendency and large generation by several types of productive activities. This work evaluated the application of TiO2, synthesized by sol-gel and precipitation methods, for phenol degradation and phenolic industrial effluent treatment. In general, after 90 minutes of treatment, these materials allowed to rich a reduction of 90% in the phenol content and of 30% in the total organic carbon concentration. These results were superior those obtained using TiO2 P25 (commercial material usually employed in this kind of treatment). The application of these synthesized materials in the remediation of a real complex matrix (industrial effluent) also showed an improvement in the phenol reduction (about 16%) in comparison with the commercial catalysis. Besides the TiO2 synthesis, the semiconductor surface modification with silver and copper was also evaluated aiming to increase the photodegradation process efficiency. The silver and copper deposition on TiO2 P25 particles promoted an increase of 15 and 45% in average capacity of phenol and organic carbon reduction, respectively. The superficial modification of TiO2 synthesized either for sol-gel or precipitation allowed an average improvement in the catalytic efficiency of 30% for phenol mineralization and 98% to phenol concentration reduction. It was observed an increase of 32% in the mineralization and of 98% in the phenol content reduction applying these modified catalysis in the treatment of a phenolic effluent. In general, the synthesis of TiO2 and its superficial modification with silver and copper have showed a promising alternative to allow a future application of these catalysts in the phenolic effluents remediation.

Leung, Tsz Yan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 132-146). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / Table of Contents --- p.vii / List of Figures --- p.xii / List of Plates --- p.xiv / List of Tables --- p.xvii / Abbreviations --- p.xviii / Equations --- p.xxi / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Water crisis and water disinfection --- p.1 / Chapter 1.2 --- Common disinfection methods --- p.2 / Chapter 1.2.1 --- Chlorination --- p.2 / Chapter 1.2.2 --- Ozonation --- p.4 / Chapter 1.2.3 --- Ultraviolet-C (UV-C) irradiation --- p.6 / Chapter 1.2.4 --- Solar disinfection (SODIS) --- p.7 / Chapter 1.2.5 --- Mixed disinfectants --- p.9 / Chapter 1.2.6 --- Other disinfection methods --- p.10 / Chapter 1.3 --- Advanced oxidation processes (AOPs) --- p.11 / Chapter 1.4 --- Photocatalytic oxidation (PCO) --- p.13 / Chapter 1.4.1 --- Understanding of PCO process --- p.15 / Chapter 1.4.2 --- Proposed disinfection mechanism of PCO --- p.18 / Chapter 1.4.3 --- Titanium dioxide (Ti02) photocatalyst --- p.21 / Chapter 1.4.4 --- Irradiation sources --- p.22 / Chapter 1.4.5 --- Bacterial species --- p.23 / Chapter 1.4.5.1 --- Escherichia coli K12 --- p.23 / Chapter 1.4.5.2 --- Shigella sonnei --- p.24 / Chapter 1.4.5.3 --- Alteromonas alvinellae --- p.25 / Chapter 1.4.5.4 --- Photobacterium phosphoreum --- p.26 / Chapter 1.4.6 --- Bacterial defense mechanism towards oxidative stress --- p.27 / Chapter 1.4.6.1 --- Superoxide dismutase (SOD) activity --- p.28 / Chapter 1.4.6.2 --- Catalase (CAT) activity --- p.29 / Chapter 1.4.6.3 --- Fatty acid (FA) profile --- p.30 / Chapter 1.4.7 --- Significance of the project --- p.31 / Chapter 2. --- Objectives --- p.34 / Chapter 3. --- Material and Methods --- p.36 / Chapter 3.1 --- Chemicals --- p.36 / Chapter 3.2 --- Screening of freshwater and marine bacterial culture --- p.36 / Chapter 3.3 --- Photocatalytic reaction --- p.39 / Chapter 3.3.1 --- Preparation of reaction mixture --- p.39 / Chapter 3.3.2 --- Preparation of bacterial culture --- p.39 / Chapter 3.3.3 --- Photocatalytic reactor --- p.41 / Chapter 3.3.4 --- PCO disinfection reaction --- p.42 / Chapter 3.3.4.1 --- Effect of initial pH --- p.44 / Chapter 3.3.4.2 --- Effect of reaction temperature --- p.45 / Chapter 3.3.4.3 --- Effect of growth phases --- p.45 / Chapter 3.4 --- Measurement of superoxide dismutase (SOD) activity --- p.47 / Chapter 3.5 --- Measurement of catalase (CAT) activity --- p.49 / Chapter 3.6 --- Fatty acid (FA) profile --- p.50 / Chapter 3.7 --- Bacterial regrowth test --- p.51 / Chapter 3.8 --- Atomic absorption spectrophotometry (AAS) --- p.52 / Chapter 3.9 --- Total organic carbon (TOC) analysis --- p.53 / Chapter 3.10 --- Chlorination --- p.55 / Chapter 3.11 --- UV-C irradiation --- p.56 / Chapter 3.12 --- Transmission electron microscopy (TEM) --- p.56 / Chapter 4. --- Results --- p.60 / Chapter 4.1 --- Screening of UV-A resistant freshwater and marine bacteria --- p.60 / Chapter 4.2 --- Control experiments --- p.62 / Chapter 4.3 --- Treatment experiments --- p.65 / Chapter 4.3.1 --- UV-A irradiation from lamps --- p.65 / Chapter 4.3.2 --- Fluorescent light from fluorescent lamps --- p.65 / Chapter 4.3.3 --- Effect of initial pH --- p.67 / Chapter 4.3.4 --- Effect of reaction temperature --- p.70 / Chapter 4.3.5 --- Effect of growth phases --- p.70 / Chapter 4.4 --- Factors affecting bacterial sensitivity towards PCO --- p.73 / Chapter 4.4.1 --- Superoxide dismutase (SOD) and catalase (CAT) activities --- p.73 / Chapter 4.4.2 --- Superoxide dismutase (SOD) and catalase (CAT) induction --- p.74 / Chapter 4.4.3 --- Fatty acid (FA) profile --- p.75 / Chapter 4.5 --- Bacterial regrowth test --- p.78 / Chapter 4.6 --- Disinfection mechanisms of fluorescent light-driven photocatalysis --- p.79 / Chapter 4.6.1 --- Atomic absorption spectrophotometry (AAS) --- p.79 / Chapter 4.6.2 --- Total organic carbon (TOC) analysis --- p.81 / Chapter 4.6.3 --- Transmission electron microscopy (TEM) --- p.83 / Chapter 4.7 --- Chlorination --- p.89 / Chapter 4.7.1 --- Disinfection efficiency --- p.89 / Chapter 4.7.2 --- Transmission electron microscopy (TEM) --- p.92 / Chapter 4.8 --- UV-C irradiation --- p.96 / Chapter 4.8.1 --- Disinfection efficiency --- p.96 / Chapter 4.8.2 --- Transmission electron microscopy (TEM) --- p.96 / Chapter 5. --- Discussions --- p.103 / Chapter 5.1 --- Screening of UV-A resistant freshwater and marine bacteria --- p.103 / Chapter 5.2 --- Comparison of PCO coupled with UV-A lamps and fluorescent lamps --- p.103 / Chapter 5.3 --- Effect of initial pH --- p.105 / Chapter 5.4 --- Effect of reaction temperature --- p.106 / Chapter 5.5 --- Effect of growth phases --- p.107 / Chapter 5.6 --- Factors affecting bacterial sensitivity towards PCO --- p.108 / Chapter 5.6.1 --- Superoxide dismutase (SOD) and catalase (CAT) activities --- p.108 / Chapter 5.6.2 --- Superoxide dismutase (SOD) and catalase (CAT) induction --- p.110 / Chapter 5.6.3 --- Fatty acid (FA) profile --- p.110 / Chapter 5.6.4 --- Cell wall structure --- p.112 / Chapter 5.6.5 --- Bacterial size --- p.114 / Chapter 5.6.6 --- Other possible factors --- p.114 / Chapter 5.7 --- Bacterial regrowth test --- p.115 / Chapter 5.8 --- Disinfection mechanisms of fluorescent light-driven photocatalysis --- p.116 / Chapter 5.8.1 --- Atomic absorption spectrophotometry (AAS) --- p.116 / Chapter 5.8.2 --- Total organic carbon (TOC) analysis --- p.117 / Chapter 5.8.3 --- Transmission electron microscopy (TEM) --- p.118 / Chapter 5.9 --- Chlorination --- p.122 / Chapter 5.9.1 --- Disinfection efficiency --- p.122 / Chapter 5.9.2 --- Transmission electron microscopy (TEM) --- p.122 / Chapter 5.10 --- UV-C irradiation --- p.123 / Chapter 5.10.1 --- Disinfection efficiency --- p.123 / Chapter 5.10.2 --- Transmission electron microscopy (TEM) --- p.124 / Chapter 5.11 --- Comparisons of three disinfection methods --- p.124 / Chapter 6. --- Conclusions --- p.126 / Chapter 7. --- References --- p.132

So, Wai Man. / Thesis submitted in: October 2007. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 112-124). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / Table of Contents --- p.vi / List of Figures --- p.x / List of Plates --- p.viii / List of Tables X --- p.v / Abbreviations --- p.xvii / Equations --- p.xix / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Importance of water disinfection --- p.1 / Chapter 1.2 --- Conventional disinfection methods --- p.2 / Chapter 1.2.1 --- Chlorination --- p.2 / Chapter 1.2.2 --- Ozonation --- p.3 / Chapter 1.2.3 --- Ultraviolet-C (UV-C) irradiation --- p.4 / Chapter 1.2.4 --- Sunlight irradiation --- p.5 / Chapter 1.2.5 --- Others --- p.6 / Chapter 1.3 --- Photocatalytic oxidation --- p.7 / Chapter 1.3.1 --- Reactions in PCO --- p.8 / Chapter 1.3.2 --- Disinfection mechanism of PCO --- p.11 / Chapter 1.3.3 --- Photocatalysts --- p.14 / Chapter 1.3.3.1 --- Titanium dioxide (TiO2) --- p.14 / Chapter 1.3.3.2 --- Modification of TiO2 --- p.15 / Chapter 1.3.3.2.1 --- Sulphur cation-doped TiO2 (S-TiO2) --- p.17 / Chapter 1.3.3.2.2 --- Copper(I) oxide-sensitized P-25 (Cu20/P-25) --- p.18 / Chapter 1.3.3.2.3 --- Silicon dioxide-doped TiO2 (SiO2-TiO2) --- p.18 / Chapter 1.3.3.2.4 --- Nitrogen-doped TiO2 (N-TiO2) --- p.19 / Chapter 1.4 --- Bacterial defense systems against oxidative stress --- p.20 / Chapter 1.5 --- Bacterial species --- p.22 / Chapter 1.5.1 --- Salmonella typhimurium --- p.23 / Chapter 1.5.2 --- Klebsiella pneumoniae --- p.24 / Chapter 1.5.3 --- Bacillus thuringiensis --- p.25 / Chapter 1.5.3 --- Bacillus pasteurii --- p.26 / Chapter 2. --- Objectives --- p.27 / Chapter 3. --- Material and Methods --- p.28 / Chapter 3.1 --- Culture media and diluents --- p.28 / Chapter 3.2 --- Screening of target bacteria --- p.28 / Chapter 3.3 --- PCO disinfection reaction --- p.29 / Chapter 3.3.1 --- Photocatalysts --- p.29 / Chapter 3.3.2 --- Bacterial cultures --- p.31 / Chapter 3.3.3 --- PCO reactor --- p.32 / Chapter 3.3.4 --- PCO efficacy test --- p.34 / Chapter 3.3.5 --- Comparison of different photocatalysts --- p.35 / Chapter 3.4 --- Optimization of PCO disinfection conditions --- p.35 / Chapter 3.5 --- Transmission electron microscopy (TEM) --- p.39 / Chapter 3.6 --- Superoxide dismutase (SOD) activity assay --- p.42 / Chapter 3.7 --- Catalase (CAT) activity assay --- p.44 / Chapter 3.8 --- Spore staining --- p.45 / Chapter 3.9 --- Atomic absorption spectrophotometry (AAS) --- p.45 / Chapter 3.10 --- X-ray photoelectron spectrometry (XPS) --- p.46 / Chapter 4. --- Results --- p.47 / Chapter 4.1 --- Screening of wastewater bacteria --- p.47 / Chapter 4.2 --- PCO efficacy test --- p.49 / Chapter 4.3 --- PCO under visible light irradiation --- p.53 / Chapter 4.3.1 --- Fluorescence lamps with UV filter --- p.53 / Chapter 4.3.2 --- Solar lamp with UV filter --- p.61 / Chapter 4.3.3 --- Sunlight with UV filter --- p.67 / Chapter 4.4 --- Optimization of PCO disinfection conditions --- p.75 / Chapter 4.4.1 --- Effect of visible light intensities --- p.75 / Chapter 4.4.2 --- Effect of photocatalyst concentrations --- p.77 / Chapter 4.4.3 --- Optimized conditions --- p.79 / Chapter 4.5 --- Transmission electron microscopy (TEM) --- p.79 / Chapter 4.6 --- Superoxide dismutase (SOD) activity assay --- p.83 / Chapter 4.7 --- Catalase (CAT) activity assay --- p.84 / Chapter 4.8 --- Spore staining --- p.85 / Chapter 4.9 --- Studies on Cu20/P-25 --- p.88 / Chapter 4.9.1 --- Atomic absorption spectrophotometry (AAS) --- p.88 / Chapter 4.9.2 --- X-ray photoelectron spectrometry (XPS) --- p.88 / Chapter 5. --- Discussion --- p.90 / Chapter 5.1 --- Screening of wastewater bacteria --- p.90 / Chapter 5.2 --- PCO efficacy test --- p.90 / Chapter 5.3 --- Comparison between different light sources --- p.90 / Chapter 5.4 --- Comparison between different photocatalysts --- p.93 / Chapter 5.5 --- Optimization of PCO disinfection conditions --- p.95 / Chapter 5.5.1 --- Effect of visible light intensities --- p.95 / Chapter 5.5.2 --- Effect of photocatalyst concentrations --- p.96 / Chapter 5.6 --- Transmission electron microscopy (TEM) --- p.97 / Chapter 5.7 --- Comparison between different bacterial species --- p.99 / Chapter 5.8 --- Possible factors affecting susceptibility of bacteria towards PCO --- p.99 / Chapter 5.8.1 --- Formation of endospores --- p.99 / Chapter 5.8.2 --- Differences in cell wall structure --- p.100 / Chapter 5.8.3 --- SOD and CAT activities --- p.101 / Chapter 5.9 --- Dark control of Cu20/P-25 --- p.103 / Chapter 5.10 --- Studies on Cu20/P-25 --- p.104 / Chapter 6. --- Conclusion --- p.107 / Chapter 7. --- References --- p.112 / Chapter 8. --- Appendix --- p.125 / Chapter 8.1 --- Production of S-Ti02 --- p.125 / Chapter 8.2 --- Production of Si02-Ti02 --- p.125 / Chapter 8.3 --- Production of N-Ti02 --- p.125

Este trabalho de mestrado descreve a avaliação do emprego do TiO2, obtido por diferentes rotas de sínteses e do TiO2 P25 ambos modificados superficialmente com prata e cobre, como catalisador no processo de fotocátalise heterogênea visando a degradação de fenol e efluentes industriais, especificamente efluentes fenólicos. A deterioração dos recursos hídricos é uma das maiores preocupações da sociedade moderna. Dentre os principais responsáveis pela diminuição sistemática na qualidade dos sistemas aquáticos, destacam-se os compostos orgânicos poluentes presentes em efluentes industriais. Dentre esta vasta gama de compostos, os fenóis mostram-se especialmente deletérios ao meio ambiente, devido a sua elevada toxicidade, tendência a bioacumulação e grandes quantidades em que são gerados pelos mais diversos tipos de atividades produtivas. Este trabalho avaliou a aplicação do TiO2 sintetizado pelos métodos de sol-gel e precipitação homogênea na degradação de fenol e no tratamento de efluentes industriais fenólicos. De um modo geral, após 90 minutos de tratamento estes materiais permitiram uma redução de 90% no teor de fenol e de 30% na concentração de carbono orgânico total. Estes resultados são superiores aos obtidos empregando-se TiO¬2 P25 (material comercial mais utilizado neste tipo de processo). A aplicação destes materiais sintetizados na remediação de uma matriz real complexa (efluente industrial) também mostrou uma melhoria na redução de fenol (cerca de 16%) em comparação ao catalisador comercial. Além da síntese do TiO2, também avaliou-se a modificação da superfície das partículas deste semicondutor com prata e cobre visando mais uma vez um aumento na eficiência do processo de fotodegradação. A deposição de prata ou cobre nas partículas do TiO2 P25 promoveu um aumento na capacidade de redução média de fenol e carbono orgânico deste poluente de 15 e 45%, respectivamente. A modificação superficial do TiO2 sintetizado tanto por sol-gel quanto por precipitação homogênea gerou um aumento médio na eficiência catalítica do semicondutor de 30% na mineralização de fenol e 98% na redução da concentração inicial desta espécie. Aplicando estes catalisadores modificados no tratamento do efluente fenólico houve um aumento na mineralização de 32% e uma redução na concentração inicial de fenol de 98% do efluente fenólico. De maneira geral a síntese do TiO2 e a modificação superficial das partículas do catalisador com prata e cobre mostraram-se bastante promissoras para uma futura aplicação destes materiais na remediação de efluentes fenólicos. / This work describes the evaluation of TiO2, obtained from different synthesis routs and superficially modified with silver and copper, as the catalyst in the heterogeneous photocatalysis process to promote phenol degradation and industrial effluents remediation, specifically phenolic effluents. The deterioration of water resources is one the greatest concerns of modern society. Among many responsible for the systematic decreases in the aquatic systems quality, special attention has been give to the organic pollutant compounds presents in the industrial effluents. Among this wide range compounds, the phenols have been showed many deleterious effect to the environment, especially because their high toxicity, bioaccumulation tendency and large generation by several types of productive activities. This work evaluated the application of TiO2, synthesized by sol-gel and precipitation methods, for phenol degradation and phenolic industrial effluent treatment. In general, after 90 minutes of treatment, these materials allowed to rich a reduction of 90% in the phenol content and of 30% in the total organic carbon concentration. These results were superior those obtained using TiO2 P25 (commercial material usually employed in this kind of treatment). The application of these synthesized materials in the remediation of a real complex matrix (industrial effluent) also showed an improvement in the phenol reduction (about 16%) in comparison with the commercial catalysis. Besides the TiO2 synthesis, the semiconductor surface modification with silver and copper was also evaluated aiming to increase the photodegradation process efficiency. The silver and copper deposition on TiO2 P25 particles promoted an increase of 15 and 45% in average capacity of phenol and organic carbon reduction, respectively. The superficial modification of TiO2 synthesized either for sol-gel or precipitation allowed an average improvement in the catalytic efficiency of 30% for phenol mineralization and 98% to phenol concentration reduction. It was observed an increase of 32% in the mineralization and of 98% in the phenol content reduction applying these modified catalysis in the treatment of a phenolic effluent. In general, the synthesis of TiO2 and its superficial modification with silver and copper have showed a promising alternative to allow a future application of these catalysts in the phenolic effluents remediation.