Síntese, caracterização e aplicação de microtubos de TiO2-ag em águas contaminadas por coliformes totais e E. coli
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2022-03-04
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Universidade Estadual Paulista (Unesp)
Resumo
Com o crescimento da população mundial e da indústria, houve um expressivo aumento no nível de poluição em geral. Grande parte dessa poluição está relacionada ao descarte incorreto de efluentes que poluem as águas de rios, lagos, etc. A demanda por técnicas que possam minimizar tais problemas tem sido crescente nos últimos anos. Uma dessas técnicas envolve as Espécies Reativas de Oxigênio (EROs), que possuem o potencial para degradar contaminantes orgânicos e eliminar bactérias, como os coliformes totais e a Escherichia coli (E. coli). Um dos materiais mais utilizados na produção de EROs é o dióxido de titânio (TiO2), material semicondutor que se destaca devido à sua propriedade fotocatalítica. Quando este material é fotoativado por luz ultravioleta, ocorre a formação dos EROs, permitindo a eliminação de contaminantes orgânicos. Neste trabalho, o TiO2 foi utilizado no desenvolvimento de um sistema de filtro fotocatalítico que possibilitou a eliminação de bactérias presentes em água contaminada por coliformes totais e E. coli. O TiO2 foi sintetizado por uma rota sintética envolvendo oxisulfato de titânio dissolvido em água deionizada e peroxido de hidrogênio. Na síntese, foi avaliada a influência da temperatura na eficiência fotocatalítica e na morfologia do TiO2. Verificou-se que, a síntese a 36 °C proporcionou a formação de microtubos de TiO2 com heterojunção das fases anatase/rutilo, o que promoveu um aumento na eficiência fotocatalítica com a mistura de fase. Um aumento da eficiência fotocatalítica também foi alcançado com a incorporação de prata (Ag) na superfície dos microtubos de TiO2. A otimização da atividade fotocatalítica foi alcançada com incorporação de aproximadamente 0,9% de Ag em relação à massa de TiO2. Os filtros fotocatalíticos obtidos com a incorporação de microtubos de TiO2 mostraram alta eficiência na formação de EROs. A eficiência foi avaliada utilizando o corante Rodamina-B e água contaminada com coliformes totais e a E. coli. Os resultados mostraram uma grande redução no número de bactérias e na degradação do corante. Com a utilização do sistema de filtração duplo com incorporação de microtubos de TiO2-Ag, houve a erradicação total dos coliformes totais e E. coli com apenas uma passagem da água contaminada pelo sistema com um fluxo máximo de 264 litros por hora. Em síntese, os resultados obtidos neste trabalho demonstram que os filtros fotocatalíticos desenvolvidos se mostraram eficientes para a descontaminação de águas contaminadas com micro-organismos como os coliformes totais e a E. coli.
In face of the world population and industry growth, there has been a huge increase in the level of pollution in general. A large part of this pollution is related to the incorrect disposal of effluents that pollute the waters of rivers, lakes, etc. The demand for techniques that can minimize such problems has been increasing in recent years. One of these techniques involves Reactive Oxygen Species (ROS), which have the potential to degrade organic contaminants and eliminate bacteria, such as total coliforms and Escherichia coli (E. coli). One of the most used materials in the production of ROS is titanium dioxide (TiO2), a semiconductor material that stands out due to its photocatalytic property. When this material is photoactivated by ultraviolet light, the formation of ROS occurs, which allows the elimination of organic contaminants. In this research, TiO2 was used in the development of a photocatalytic filter system that allowed the elimination of bacteria present in water that was contaminated by total coliforms and E. coli. TiO2 was synthesized by a synthetic route involving titanium oxysulfate dissolved in deionized water and hydrogen peroxide. In the synthesis, the influence of temperature on the photocatalytic efficiency and the morphology of TiO2 was evaluated. It was found that, when the synthesis occurs at 36 °C, it provides the formation of TiO2 microtubes with heterojunction of the anatase/rutile phases, which promoted an increase in photocatalytic efficiency with the phase mixture. An increase in photocatalytic efficiency was also achieved with the incorporation of silver (Ag) on the surface of the TiO2 microtubes. The optimization of the photocatalytic activity was achieved with the incorporation of approximately 0.9% of Ag concerning the mass of TiO2. The photocatalytic filters obtained with the incorporation of TiO2 microtubes showed high efficiency in the formation of ROS. Efficiency was evaluated using Rhodamine-B dye and water contaminated with total coliforms and E. coli. The results showed reduction in the number of bacteria and the degradation of the dye. With the use of the double filtration system with the incorporation of TiO2-Ag microtubes, the total eradication of total coliforms and E. coli was observed with only one passage of contaminated water through the system with a maximum flow of 264 liters per hour. In short, the results obtained in this work showed that the photocatalytic filters developed proved to be efficient for the decontamination of water contaminated with microorganisms such as total coliforms and E. coli.
In face of the world population and industry growth, there has been a huge increase in the level of pollution in general. A large part of this pollution is related to the incorrect disposal of effluents that pollute the waters of rivers, lakes, etc. The demand for techniques that can minimize such problems has been increasing in recent years. One of these techniques involves Reactive Oxygen Species (ROS), which have the potential to degrade organic contaminants and eliminate bacteria, such as total coliforms and Escherichia coli (E. coli). One of the most used materials in the production of ROS is titanium dioxide (TiO2), a semiconductor material that stands out due to its photocatalytic property. When this material is photoactivated by ultraviolet light, the formation of ROS occurs, which allows the elimination of organic contaminants. In this research, TiO2 was used in the development of a photocatalytic filter system that allowed the elimination of bacteria present in water that was contaminated by total coliforms and E. coli. TiO2 was synthesized by a synthetic route involving titanium oxysulfate dissolved in deionized water and hydrogen peroxide. In the synthesis, the influence of temperature on the photocatalytic efficiency and the morphology of TiO2 was evaluated. It was found that, when the synthesis occurs at 36 °C, it provides the formation of TiO2 microtubes with heterojunction of the anatase/rutile phases, which promoted an increase in photocatalytic efficiency with the phase mixture. An increase in photocatalytic efficiency was also achieved with the incorporation of silver (Ag) on the surface of the TiO2 microtubes. The optimization of the photocatalytic activity was achieved with the incorporation of approximately 0.9% of Ag concerning the mass of TiO2. The photocatalytic filters obtained with the incorporation of TiO2 microtubes showed high efficiency in the formation of ROS. Efficiency was evaluated using Rhodamine-B dye and water contaminated with total coliforms and E. coli. The results showed reduction in the number of bacteria and the degradation of the dye. With the use of the double filtration system with the incorporation of TiO2-Ag microtubes, the total eradication of total coliforms and E. coli was observed with only one passage of contaminated water through the system with a maximum flow of 264 liters per hour. In short, the results obtained in this work showed that the photocatalytic filters developed proved to be efficient for the decontamination of water contaminated with microorganisms such as total coliforms and E. coli.
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Palavras-chave
Dióxido de titânio, Fotocatálise, Coliformes totais, E. coli, Prata