Neste trabalho é apresentado o estudo da degradação eletroquímica de fenol, formaldeído e misturas de fenol-formaldeído sobre ânodos dimensionalmente estáveis (ADE). Foi utilizado um ADE comercial (composição nominal Ti/Ti0,7Ru0,3O2), em uma célula eletroquímica de compartimento único sob agitação constante. As concentrações utilizadas nas misturas de fenol-formaldeído foram similares às concentrações encontradas no efluente fornecido pela indústria de resinas fenólicas Schenectady Crios, localizada na cidade de Rio Claro, SP. No final do trabalho também foi feita a degradação eletroquímica do efluente industrial com os melhores parâmetros. O recobrimento do ADE foi caracterizado por Microscopia Eletrônica de Varredura (MEV) e análises de Energia Dispersiva de Raios X (EDX). A caracterização eletroquímica foi feita por voltametria cíclica na ausência e na presença das substâncias orgânicas sob estudo. Durantes as eletrólises, a degradação das substâncias inicialmente presentes em solução foi verificadas por análises de Cromatografia Líquida de Alta Eficiência (CLAE) e Carbono Orgânico Total (COT). Os subprodutos formados (ácido fórmico, benzoquinona, hidroquinona, catecol e resorcinol) também foram identificados e quantificados por CLAE. Cálculos de estimativa do consumo energético também foram realizados para cada eletrólise.Foram variados os seguintes parâmetros: as densidades de corrente aplicadas, o controle da temperatura das soluções durante as eletrólises, o pH e as concentrações iniciais de fenol e formaldeído contidas nas soluções.O decaimento das concentrações das substâncias orgânicas apresenta uma cinética de pseudo primeira ordem. Observou se que quanto maior a densidade de corrente aplicada, maior é a taxa de remoção de COT, porém o consumo energético também é maior. Não se obteve a mineralização total do poluente, porém foi possível atingir uma remoção de aproximadamente 90% de COT para as soluções contendo apenas formaldeído, aplicando uma densidade de corrente de 40 mA cm-2 durante 2 horas de eletrólise. Foi possível a identificação e a quantificação dos subprodutos presentes nas soluções e no efluente industrial. As degradações eletroquímicas realizadas sem o controle da temperatura das soluções obtiveram um consumo energético menor e maior remoção de COT. / In this work presents the study of electrochemical degradation of phenol, formaldehyde and phenol-formaldehyde mixtures at dimensionally stable anodes (DSA®). Commercial DSA® electrodes (nominal composition: Ti/Ti0,7Ru0,3O2), ) were employed in a single compartment electrochemical cell under constant agitation. The concentrations used for the mixtures of phenol-formaldehyde were similar to concentrations found in effluent provided by the phenolic resin producer Crios Schenectady, located in Rio Claro, São Paulo state. In the final stage of the present study, the electrochemical degradation of real industrial effluent was performed employing the best parameters observed for the simulated effluents. The oxide coating of the electrode was characterized by Scanning Electron Microscopy (SEM) and Energy Dispersive X Ray analyses (EDX). The electrochemical characterization of the DSA® was performed using cyclic voltammetry in the absence and presence of organic substances. The degradation of the substances inicially present in solution were monitored by High Performance Liquid Chromatography (HPLC) and Total Organic Carbon (TOC) analyses. The products formed (formic acid, benzoquinone, hydroquinone, catechol and resorcinol) were also identified and quantified by HPLC. Estimates of the energy consumption were also performed for each electrolysis.The current densities applied, the concentrations of organic substance of the solution were varied during the electrochemical oxidation.The concentration decay of organic substances displayed pseudo first order kinetics of. It was observed that the higher the applied current density, the higher the TOC removal rate , but the energy consumption is higher. Total mineralization was not attained, but removals of approximately 90% of TOC were shown to be possible. It was possible the identification and quantification of products into the solutions and industrial effluents. The electrochemical degradation carried out without controlling the temperature of the solutions obtained a lower energy consumption and higher removal of TOC.

A presente pesquisa objetivou estudar a remoção dos poluentes presentes em uma água residuária de coqueria, através do processo biológico de nitritação/desnitritação operando um reator de lodo ativado em bateladas seqüenciais em duas etapas sucessivas. Durante a primeira, o reator foi alimentado com um efluente sintético composto por dois poluentes abundantes em despejos de coqueria: nitrogênio amoniacal (500 mg N/L) e fenol (1.000 mg C6H5OH/L). Na segunda, o reator foi alimentado com o despejo gerado na unidade de coqueria de uma indústria siderúrgica integrada. Ao longo da primeira etapa, ao final da fase aeróbia dos 28 ciclos de tratamento, foi possível alcançar eficiências de remoção de N-NH3 superiores a 90% com predominância do N-NO2 - na massa líquida do reator evidenciado pelas relações N-NO2 -/ (N-NO2 - + N-NO3 -) superiores a 86%. O principal mecanismo de inibição das bactérias oxidantes de nitrito (BON) foram concentrações de amônia livre no conteúdo do reator entre 3,2 e 19,5 mg NH3/L. As taxas específicas de nitritação variaram entre 0,03 e 0,11 kg N-NH3/ kg SSV.dia, para temperaturas no conteúdo do reator entre 15 e 34°C. Durante a fase anóxica, o fenol mostrou-se adequado como fonte de carbono para a biomassa desnitritante, desde que as taxas de aplicação volumétricas fossem inferiores a 0,02 kg fenol/m³.hora. Respeitando essa condição, foi possível alcançar: eficiências de remoção de fenol entre 45 e 56%; taxas específicas de remoção de fenol entre 0,03 e 0,09 kg C6H5OH / kg SSV.dia; taxas específicas de desnitritação entre 0,03 e 0,06 kg N-NO2 -/ kg SSV.dia e eficiências de remoção de (N-NO2 - + N-NO3 -) superiores a 95%. Ao longo da fase anóxica foram retiradas amostras do conteúdo do reator para a realização de análises de nitrofenóis (NF). Os resultados acusaram a presença de 2 nitrofenol e 4 nitrofenol em concentrações proporcionais à taxa de aplicação volumétrica do fenol na massa líquida do reator. A presença desses compostos em concentrações inferiores a 0,5 mg/L não causou impacto sobre a desnitritação biológica. As análises realizadas em amostras coletadas ao final da reação anóxica, não acusaram a presença de 2 e 4 NF, demonstrando que esses compostos podem ser biodegradados por uma biomassa bem adaptada ao fenol. A concepção do sistema para tratamento da água residuária de coqueria via nitritação/desnitritação envolveu a operação de dois reatores (principal e reator de polimento) operados em bateladas seqüenciais. As condições de operação do reator principal eram manipuladas para viabilizar o acúmulo de NNO2 - ao final da fase aeróbia e promover a desnitritação durante a fase anóxica, utilizando como fonte de carbono a própria matéria orgânica presente no despejo. Como o sobrenadante do reator principal apresentava concentrações elevadas de N-NO2 -, esse efluente era aplicado no reator de polimento, juntamente com etanol como fonte de carbono para redução do NNO2 -. Ao final da fase aeróbia dos ciclos de tratamento conduzidos no reator principal alcançaram-se: relações NO2 -/ (N-NO2 - + N-NO3 -) superiores a 88%; eficiências de remoções de nitrogênio total superiores a 60%; remoções de N-NH3 superiores a 90%, para valores de pH na massa líquida do reator entre 7,8 e 8,5 e, temperatura entre 23 e 31°C. Tal qual ocorrido durante a primeira etapa da investigação, o principal mecanismo de inibição da atividade das bactérias oxidantes de nitrito foi a toxicidade conferida pelas concentrações de amônia livre (3,7 a 15,7 mg NH3/L) no conteúdo do reator. Durante a fase anóxica, as eficiências de remoção de (N-NO2 - foram limitadas pela disponibilidade de matéria orgânica biodegradável no despejo da coqueria, razões DBO/DQOafluente superiores a 80% resultaram em remoções de N-NO2 - próximas de 100%. Quanto ao reator de polimento, pode-se afirmar que o etanol teve um efeito positivo sobre a remoção de matéria orgânica da água residuária da coqueria, considerando a configuração (dois lodos) utilizada. / The present research aimed to study the coke-oven wastewater treatment over nitritation/denitritation in an activated sludge sequencing batch reactor in two successive phases. During the first one, the reactor was fed with a synthetic effluent composed by two abundant pollutants present in coke-oven wastewaters: total ammonia nitrogen (500 mg TAN.l-1) and phenol (1,000 mg C6H5OH.l-1). During the second phase, the reactor was fed with the wastewater produced in an integrated steel industrys coke-plant. The results of the first phase (28 cycles) showed that was possible to achieve TAN removal efficiencies higher than 90% with NO2 --N predominance in the reactor content, evidenced by the rates NO2 --N/ (NO2 --N + NO3 --N) higher than 86%. The main mechanism of the nitrite oxidizer bacteria (NOB) inhibition was free ammonia concentrations between 3.2 and 19.5 mg NH3.l-1. The specific nitritation rates varied between 0.03 and 0.11 kg TAN. kg VSS-1.d-1, for temperatures between 15 and 34oC. Phenol showed to be suitable as carbon source for denitrifying biomass, once the volumetric application rates were lower than 0.02 kg phenol.m-3.h-1. Obeying this condition, it was possible to achieve: phenol removal efficiencies between 45 and 56%; specific phenol removal rates between 0.03 and 0.09 kg C6H5OH. kg VSS-1.d-1; specific denitritation rates between 0.03 and 0.06 kg NO2 --N . kg VSS-1.d-1 and removal efficiencies of (NO2 --N + NO3 --N) higher than 95%. During the anoxic phase, samples were collected from the reactor content for nitrophenols analyses. The results showed the presence of 2- nitrophenol (2-NP) and 4-nitrophenol (4-NP) in concentrations proportional to phenol volumetric application rate in the reactor liquid mass. The presence of those compounds in concentrations lower than 0.5 mg/L does not cause impact over the biological denitritation. The analyses accomplished in samples collected at the end of the anoxic reaction do not show the presence of 2 and 4-NP, demonstrating that these compounds can be biodegraded by a well-adapted biomass. The arrangement of the system for the treatment of coke-oven wastewater (Phase 02) over nitritation/denitritation involved the operation of two sequencing batch reactors (the main reactor and the polishing one). The operational conditions of the main reactor were manipulated to make feasible the NO2 --N accumulation at the end of the aerobic stage and promote the denitritation using the own organic matter present in the cokeoven wastewater as carbon source. As the supernatant of the main reactor presented high nitrite concentrations, this effluent was conducted to a biological denitrifying polishing reactor with ethanol as carbon source. At the end of the aerobic stage of the treatment cycles conducted in the main reactor, it was achieved: NO2 --N/ (NO2 --N + NO3 --N) higher than 88%; total nitrogen removal efficiencies higher than 60%; ammonia nitrogen removal higher than 90%. As occurred during the first phase of the investigation, the main NOB activity inhibition was the toxicity of the free ammonia concentrations (3.7 to 15.7 mg NH3.l-1) in the reactor content. At the end of anoxic stage, the NO2 --N removal efficiencies were limited by the availability of the biodegradable organic matter in the coke-oven wastewater but BOD/CODinfluent higher than 80% resulted in NO2 --N removals next to 100%. Regarding to the polishing reactor, it can be stated that the ethanol had a positive effect over the organic matter removal of the coke-oven wastewater.

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.

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.

Thesis (M.Sc. (Chemistry)) --University of Limpopo, 2014 / This study deals with the synthesis and characterisation of cobalt complexes of nitrogen-donor imidazolyl- salicylaldimine ligands and their potential catalytic activity in the oxidation reactions of phenol and styrene. Five ligands were used in the study, four of which are new. Compound 2,4-di-tert-butyl-6{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L1), was synthesised according to a literature procedure. The other imidazole-based salicylaldimine compounds 2-ethoxy-6{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L2), 4-methoxy-6{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L3), 1{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-benzene (L4) and 4-methyl-1{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-benzene (L5) were prepared by Schiff base condensation reaction of histamine dihydrochloride with 3-ethoxy-2-hydroxybenzaldehyde, 5-methoxy-2-hydroxybenzaldehyde, benzaldehyde, 4-methylbenzaldehyde respectively. L1-L5 were characterised by 1H and 13C{1H} NMR, IR and UV-vis spectroscopy and high resolution mass spectrometry (HRMS). Reactions of L1-L5 with CoCl2 yielded complexes C1-C5, while complexes C6-C10 were synthesised by reactions of L1-L5 with CoBr2 all in a ratio of 1:1 of ligand to metal precursor. The cobalt(II) complexes were characterised by IR and UV-vis spectroscopy, elemental analysis and high resolution mass spectrometry due to their paramagnetic nature. All the characterisation data point to complexes C1-C10 being formulated as [Co(3-L)X] (where L = ligand and X = halide). However, single crystal X-ray diffraction showed that the prolonged stay of complex C6 in a solution gave a new structure as complex C11. The imidazole-based salicylaldimine cobalt(II) complexes (C1-C10) were tested as catalysts for the oxidation reactions of phenol and styrene with H2O2, O2 and 3-chloroperbenzoic acid as oxidants. The complexes were found not to be active for the oxidation of both substrates (phenol and styrene) with 0% conversion, even when the reactions were left for 1 week. Analysis of the oxidation reactions were performed with GC and 1H NMR spectroscopy. Both analysis methods showed the presence of unreacted substrates at the end of the reaction period. Effects of concentration of pre-catalysts, substrates and oxidants, time and temperature of reaction and nature of solvent on catalytic activity were also investigated, however the conversions remained at 0% conversion. / Sasol Inzalo Foundation

Thesis (MSc. (Chemistry)) --University of Limpopo, 2014 / This study deals with the synthesis and characterisation of cobalt complexes of nitrogen-donor imidazolyl- salicylaldimine ligands and their potential catalytic activity in the oxidation reactions of phenol and styrene. Five ligands were used in the study, four of which are new. Compound 2,4-di-tert-butyl-6{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L1), was synthesised according to a literature procedure. The other imidazole-based salicylaldimine compounds 2-ethoxy-6{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L2), 4-methoxy-6{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L3), 1{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-benzene (L4) and 4-methyl-1{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-benzene (L5) were prepared by Schiff base condensation reaction of histamine dihydrochloride with 3-ethoxy-2-hydroxybenzaldehyde, 5-methoxy-2-hydroxybenzaldehyde, benzaldehyde, 4-methylbenzaldehyde respectively. L1-L5 were characterised by 1H and 13C{1H} NMR, IR and UV-vis spectroscopy and high resolution mass spectrometry (HRMS). Reactions of L1-L5 with CoCl2 yielded complexes C1-C5, while complexes C6-C10 were synthesised by reactions of L1-L5 with CoBr2 all in a ratio of 1:1 of ligand to metal precursor. The cobalt(II) complexes were characterised by IR and UV-vis spectroscopy, elemental analysis and high resolution mass spectrometry due to their paramagnetic nature. All the characterisation data point to complexes C1-C10 being formulated as [Co(3-L)X] (where L = ligand and X = halide). However, single crystal X-ray diffraction showed that the prolonged stay of complex C6 in a solution gave a new structure as complex C11. The imidazole-based salicylaldimine cobalt(II) complexes (C1-C10) were tested as catalysts for the oxidation reactions of phenol and styrene with H2O2, O2 and 3-chloroperbenzoic acid as oxidants. The complexes were found not to be active for the oxidation of both substrates (phenol and styrene) with 0% conversion, even when the reactions were left for 1 week. Analysis of the oxidation reactions were performed with GC and 1H NMR spectroscopy. Both analysis methods showed the presence of unreacted substrates at the end of the reaction period. Effects of concentration of pre-catalysts, substrates and oxidants, time and temperature of reaction and nature of solvent on catalytic activity were also investigated, however the conversions remained at 0% conversion.

Growing demand and shortages of potable water sources due to industrialization have become a great concern worldwide. Various approaches and solutions have been adopted to provide cleaner and quality water. In a preliminary study, a method of treating wastewater was investigated in which algae were used to remove nutrients (nitrogen and phosphorous) from wastewater and then the algae were harvested for use as a biofuel. The results from this investigation are included in the Appendix B. Employing traditional oxidants, such as hydrogen peroxide, chlorine, and ozone, for treatment of recalcitrant organic compounds have achieved less promising results. However, photocatalysis, an advanced oxidation process (AOP), which is a low-cost and high-efficiency technique, has been widely recognized as a promising approach for water purification and elimination of organic constituents in wastewater. Photocatalysis is the increase in the rate of a chemical reaction by employing a catalyst in the presence of photons. Generally, for a high performance photocatalyst, light of appropriate wavelength is used to activate a catalyst in close contact with contaminants, thereby modifying the rate of the reaction. The presence of these contaminants could pose potential health and environmental concerns, especially in a controlled environment such as on a space station or during long-term manned missions. Thus, the development of energy efficient and "green" technologies to reduce or eliminate organic constituents in wastewater has important potential applications. This research investigated the supported semiconductor photocatalysts (TiO2 and ZnO), particularly ZnO nanorods and nanowires, their synthesis methods, properties and corresponding effectiveness in photocatalysis. The effect of transition metal co-catalysts on the photocatalytic properties of TiO2 was investigated. Although TiO2 is the most extensively studied photocatalyst for water decontamination, ZnO, as presented in this work, could be a substitute because of its lower cost, relative energy bandgap and higher visible light photoactivity. Both photocatalysts were doped and screened for the decomposition of model contaminates, rhodamine B (RhB), phenol and methyl orange, under ultraviolet and/or visible light irradiation. In the photodegradation of RhB, TiO2/Ru 1% showed a superior photocatalytic activity relative to P25-TiO2 under broad-band irradiation, while doped ZnO-Ag resulted in better photodegradation of methyl orange, compared to P25-TiO2, under visible light irradiation. The morphology and estimated chemical composition of photocatalysts were determined by energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). Brunhauer, Emmett and Teller (BET) analysis was utilized to measure mass-specific surface area(s). A X-ray diffraction (XRD) study was carried out to confirm the identity of photocatalyst phase(s) present. The cause of low photocatalytic activity under an inert atmosphere, the simple effective fabrication technique of doped ZnO nanowires over TiO2 and properties of the photocatalyst are also discussed.

Biodegradation is the breakdown of a compound by a biological organism. Over the past few decades, the biodegradation of compounds such as phenol has been researched extensively. Phenol research has shown that certain organisms are capable of utilising it as an energy source, and a variety of methods are available for its removal. Unfortunately, there is lack of research on phenol degradation at low concentrations. The majority of research performed on phenol degradation has used concentrations above 500 mg, while phenol is highly toxic at levels below 25 mg. The aim of this research was to pursue the problem of phenol degradation at below 100 mg and develop a system able to degrade phenol at such levels. The system consisted of a bioreactor developed to run in continuous mode, using Ps. putida immobilised in calcium alginate. A standard method was modified to quantitatively analyze effluent phenol levels, and a medium designed to increase the longevity of calcium alginate beads in continuous culture. A continuous flow bioreactor was also designed using an overflow weir for use with immobilised cells. Based on the results obtained, immobilisation offers increased stability and increased protection for cells under extreme conditions and is able to use higher dilution rates than cells under continuous culture / Master of Science (Hons)

La escasez de agua se presenta como uno de los mayores retos para asegurar el desarrollo sostenible. Entre otras actuaciones, se deben investigar e implementar sistemas eficientes de tratamiento de aguas biorecalcitrantes, que necesitan ser condicionadas antes de su depuración biológica. Uno de los posibles pre-tratamientos es el proceso Fenton de oxidación avanzada, que presenta dos principales inconvenientes: la utilización de sales de hierro como catalizador homogéneo, que abandonan continuamente la etapa de oxidación, y el elevado consumo de oxidante, en parte desaprovechado. La presente tesis se centra en el estudio de la mejora del proceso Fenton de aguas fenólicas mediante su acoplamiento con tecnologías de membrana como la nanofiltración, la emulsificación con membranas o los reactores de membrana. El acoplamiento de dichas tecnologías con el proceso Fenton permite el confinamiento del catalizador y el aumento de la eficiencia de oxidación, mejorando así el tratamiento en términos ambientales y económicos. / Water scarcity is one of the major challenges for assuring a sustainable development. Among other measures, research into efficient wastewater treatment systems to deal with biorefractory wastewaters, which need to be amended before their biological degradation, is required. The Fenton process is an advanced oxidation process that can be used as potential pre-treatment for this purpose. However, the pre-treatment presents two main limitations: the use of iron salts as homogeneous catalyst, which are continuously thrown away in the reactor effluent, and the high consumption of oxidant, which is partially wasted. The present thesis aims at studying the improvement of the Fenton process applied on phenolic wastewater through its coupling with membrane technologies such as nanofiltration, membrane emulsification or membrane reactors. The coupling allows confining the catalyst and increasing the oxidation efficiency, thus enhancing the treatment efficiency in environmental and economic terms.

The biocatalytic activity of mushroom tyrosinase was optimized in chloroform medium, using five selected phenolic substrates, including catechin (CT), vanillin (VA), chlorogenic acid (CA), p-aminophenol (pAP) and hydroquinone (HQ). The specific activity (SA) of tyrosinase determined as the change in absorbance at the selected wavelength per $ mu$g protein per sec ($ delta$A/$ mu$g protein/sec) in chloroform was much higher than that obtained in aqueous media. The optimal amount of enzymatic protein for tyrosinase biocatalysis in chloroform was found to be 44.0 mg protein/L for CT and VA, 31.6, 180.5 and 90.3 mg protein/L, respectively, for CA, pAP and HQ. The optimal pH for the oxidative activity of tyrosinase in chloroform was 6.0 for all the substrates; however, the optimal temperature for enzymatic activity was 30$ sp circ$C for CT and 25$ sp circ$C for the other four substrates. The use of 1.25 and 6.65 mM catechol in chloroform medium activated the tyrosinase activity maximally by 56.2% and 267.2%, respectively for CT and CA as substrates; however, no effect from catechol (0 to 7 mM) was found with VA, pAP or HQ. In addition, the use of 4.25, 2.25 and 5.39 mM ethylenediamine tetraacetic acid (EDTA) in chloroform, with CT, VA and pAP as substrates, inhibited the tyrosinase activity maximally by 44.3, 84.7 and 67.0%, respectively; however, the use of 4.75 and 1.60 mM EDTA activated the enzyme by 101.9% and 115.9%, respectively, for CA and HQ. The use of high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) demonstrated the phenolic substrate bioconversion, whereas the spectrophotometric scanning showed the product formation during the enzymatic reaction. (Abstract shortened by UMI.)