Degradação fotocatalítica de efluente simulado de refinaria de petróleo e monitoramento de sua toxicidade com microrganismos
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Data
2009-08-27
Autores
Lopes, Paulo Renato Matos [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O interesse científico e comercial pela catálise ambiental expandiu-se significativamente, nos últimos anos, devido ao aumento contínuo das restrições legais sobre a qualidade das emissões. Cada vez mais, surgem demandas pelo desenvolvimento de tecnologias de tratamento e remediação de água. Com isso, a catálise pode ser a peça chave neste desenvolvimento. Os efluentes industriais, como os provenientes das refinarias de petróleo, indústrias petroquímicas e coquearias, freqüentemente contêm compostos fenólicos que são tóxicos ao ambiente aquático e ao homem. Estes compostos são tratados convencionalmente através de processos biológicos, de extração e adsorção. Entretanto, estas técnicas apresentam limitações para aplicação em sistemas de concentrações intermediárias e em presença de multicomponentes fenólicos, além de representarem um elevado custo de tratamento. Dessa forma, o uso de tecnologias avançadas de oxidação catalítica vem se consolidando como uma das tendências de desenvolvimentos futuros em catálise, como a fotocatálise. Neste contexto, estão os processos oxidativos avançados (POAs), os quais se caracterizam pela capacidade de gerar radicais hidroxila que são responsáveis por oxidar compostos orgânicos. Dentre os POAs se encontra o processo fotocatalítico. A fotocatálise heterogênea é baseada na irradiação de um fotocatalisador, geralmente um semicondutor inorgânico, como o TiO2, cuja energia do fóton deve ser maior ou igual a energia do band gap do semicondutor para provocar uma transição eletrônica (excitação). Assim, o processo é capaz de oxidar os compostos orgânicos à CO2 e H2O. Entretanto, a aplicação prática da fotocatálise heterogênea em suspensões de TiO2 apresenta algumas desvantagens, como a separação final das partículas do catalisador e o baixo rendimento quântico. Através de eletrodos térmicos...
Scientific and commercial interest in environmental catalysis expanded significantly in last years due to restrictions about the emissions quality. Even more, it has been increasing the demands for the development of technologies for water treatment and remediation. Thus, catalysis may be an important technique in this area. Industrial effluents, such as petrochemical wastewater, often present phenolic compounds that are toxic to aquatic environment and humans. These compounds are conventionally treated by biological, extraction and adsorption process. However, these processes have limitation in systems with intermediate concentrations and in presence of phenol derivates, besides of represent high cost. Therefore, the use of advanced technologies of catalytic oxidation has been consolidated as one of tendencies in future developments in catalysis, such as the photocatalysis. In this context are the advanced oxidative processes (AOPs), which are able to generate hydroxyl radicals that are responsible for oxidizing organic compounds. And, within the AOPs is the photocatalysis. The heterogeneous photocatalysis is based on irradiation of a photocatalyzer that is usually an inorganic semiconductor, such as TiO2. Photon energy must be greater or equal to the semiconductor’s band gap energy to cause an electronic transition (excitation). Hence, the process is able to oxidize organic compounds to CO2 and H2O. Nevertheless, heterogeneous photocatalysis application with TiO2 suspensions presents some disadvantages, for example the final separation of catalyst particles and the low quantum yield. Through Ti/TiO2 thermal electrodes, these problems can be solves, because it becomes unnecessary the final separation of particles and it is also possible the application of an electric potential on electrode. Electric potential improves the photocatalytic efficiency due to the electronic drainage that... (Complete abstract click electronic access below)
Scientific and commercial interest in environmental catalysis expanded significantly in last years due to restrictions about the emissions quality. Even more, it has been increasing the demands for the development of technologies for water treatment and remediation. Thus, catalysis may be an important technique in this area. Industrial effluents, such as petrochemical wastewater, often present phenolic compounds that are toxic to aquatic environment and humans. These compounds are conventionally treated by biological, extraction and adsorption process. However, these processes have limitation in systems with intermediate concentrations and in presence of phenol derivates, besides of represent high cost. Therefore, the use of advanced technologies of catalytic oxidation has been consolidated as one of tendencies in future developments in catalysis, such as the photocatalysis. In this context are the advanced oxidative processes (AOPs), which are able to generate hydroxyl radicals that are responsible for oxidizing organic compounds. And, within the AOPs is the photocatalysis. The heterogeneous photocatalysis is based on irradiation of a photocatalyzer that is usually an inorganic semiconductor, such as TiO2. Photon energy must be greater or equal to the semiconductor’s band gap energy to cause an electronic transition (excitation). Hence, the process is able to oxidize organic compounds to CO2 and H2O. Nevertheless, heterogeneous photocatalysis application with TiO2 suspensions presents some disadvantages, for example the final separation of catalyst particles and the low quantum yield. Through Ti/TiO2 thermal electrodes, these problems can be solves, because it becomes unnecessary the final separation of particles and it is also possible the application of an electric potential on electrode. Electric potential improves the photocatalytic efficiency due to the electronic drainage that... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Microorganismos, Agua - Purificação, Dióxido de titânio, Fotocatalise, Radiação ultravioleta, Fenol, Potencial elétrico, Toxicidade, Phenol, Photocatalysis, Titanium dioxide, UV radiation, Electric potential, Toxicity
Como citar
LOPES, Paulo Renato Matos. Degradação fotocatalítica de efluente simulado de refinaria de petróleo e monitoramento de sua toxicidade com microrganismos. 2009. 163 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Biociências de Rio Claro, 2009.