Atividade fotocatalítica de pó de TiO2 obtido por uma nova rota sintética
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Data
2017-03-03
Autores
Montanhera, Maykon André [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Questões ambientais vêm sendo destaque nos meios de comunicação, motivando a busca por técnicas e materiais que possam amenizar os efeitos nocivos ao meio ambiente causados pelo crescimento populacional. Dentre essas técnicas, os Processos Oxidativos Avançados vêm se desenvolvendo, pois possibilitam a degradação de poluentes por meio da atividade fotocatalítica de alguns materiais semicondutores. O dióxido de titânio é um dos materiais semicondutores que se destacam nessa aplicação devido a suas propriedades físicas e químicas. No presente trabalho, o dióxido de titânio foi sintetizado por uma nova rota sintética envolvendo oxisulfato de titânio, peróxido de hidrogênio e água deionizada. Inicialmente, as amostras foram sintetizadas com diferentes concentrações de peróxido de hidrogênio e tratadas termicamente a 600 °C. A morfologia, estrutura e atividade fotocatalítica dessas amostras foram analisadas. Os resultados mostraram que concentrações a partir de 0,392 mol/L de H2O2 proporcionaram a formação de microtubos e que esta morfologia favorece a atividade fotocatalítica do dióxido de titânio. A temperatura de tratamento térmico foi outro parâmetro estudado, amostras foram sintetizadas com uma concentração fixa de 0,392 mol/L de peróxido de hidrogênio e submetidas a diferentes temperaturas. Os resultados obtidos com difratometria de raios-X mostraram a existência de fases puras anatase e rutilo, assim como fases mistas com diferentes percentuais. Dentre elas, a amostra tratada termicamente a 740 °C apresentou um percentual de 14 % de rutilo e a maior eficiência fotocatalítica. Esse aumento da eficiência foi devido à morfologia obtida via rota de síntese que proporcionou a formação de heterojunção entre as duas fases cristalográficas. Com o objetivo de possibilitar a aplicação fotocatalítica sob luz visível, foi incorporado PCBM ([6,6]-fenil C61 ácido butírico metil ester) em diferentes percentuais no dióxido de titânio. A incorporação não resultou em uma alteração na cristalinidade, mas possibilitou a fotossensibilização do dióxido de titânio para maiores comprimentos de onda, no espectro do visível. Das amostras, a que continha 2 % de PCBM foi a que apresentou a maior atividade fotocatalítica em comparação com a amostra de dióxido de titânio puro, quando irradiada por luz visível.
Environment issues have been highlighted in the media, motivating the search for techniques and materials that are able to diminish the harmful effects to the environment caused by population growth. Among these techniques, advanced oxidative processes have been developed, enabling the degradation of pollutants by the photocatalytic activity of some semiconductors materials. Titanium dioxide has been pointed out as a semiconductor material due to its physicals and chemicals properties. In the present work, the titanium dioxide was synthesized by a new synthetic route evolving titanium oxysulfate, hydrogen peroxide, deionized water. Initially, the samples were synthesized with different concentrations of hydrogen peroxide and heat treated at 600 °C. The morphology, structure and photocatalytic activity of these samples were analyzed. The results showed that concentrations of 0.392 mol/L H2O2 or higher provided microtubes formation and that this morphology favors the photocatalytic activity of titanium dioxide. The temperature of heat treatment was another parameter studied, the samples were synthesized with a fixed concentration of 0.392 mol/L of hydrogen peroxide and submitted to different temperatures. The X-ray diffraction results showed pure phase anatase and rutile, as well as mixed phases with different percentages. The sample heat treated at 740 °C presented a percentage of 14 % of rutile and higher photocatalytic efficiency. This efficiency increment was due to the morphology obtained by synthetic route, that provided the formation of heterojunction between both crystallographic phases. To achieve visible light-induced photocatalytic activity, PCBM ([6,6]-Phenyl C61 butyric acid methyl ester) was incorporated at different rates into the titanium dioxide. The incorporation did not result in any change in crystallinity, but enabled the photosensitivity of titanium dioxide for absorption spectrum to larger wavelengths, in the visible spectrum. Among the samples, the one containing 2 % of PCBM showed higher photocatalytic activity comparing to the sample of pure titanium dioxide, when irradiated by visible light.
Environment issues have been highlighted in the media, motivating the search for techniques and materials that are able to diminish the harmful effects to the environment caused by population growth. Among these techniques, advanced oxidative processes have been developed, enabling the degradation of pollutants by the photocatalytic activity of some semiconductors materials. Titanium dioxide has been pointed out as a semiconductor material due to its physicals and chemicals properties. In the present work, the titanium dioxide was synthesized by a new synthetic route evolving titanium oxysulfate, hydrogen peroxide, deionized water. Initially, the samples were synthesized with different concentrations of hydrogen peroxide and heat treated at 600 °C. The morphology, structure and photocatalytic activity of these samples were analyzed. The results showed that concentrations of 0.392 mol/L H2O2 or higher provided microtubes formation and that this morphology favors the photocatalytic activity of titanium dioxide. The temperature of heat treatment was another parameter studied, the samples were synthesized with a fixed concentration of 0.392 mol/L of hydrogen peroxide and submitted to different temperatures. The X-ray diffraction results showed pure phase anatase and rutile, as well as mixed phases with different percentages. The sample heat treated at 740 °C presented a percentage of 14 % of rutile and higher photocatalytic efficiency. This efficiency increment was due to the morphology obtained by synthetic route, that provided the formation of heterojunction between both crystallographic phases. To achieve visible light-induced photocatalytic activity, PCBM ([6,6]-Phenyl C61 butyric acid methyl ester) was incorporated at different rates into the titanium dioxide. The incorporation did not result in any change in crystallinity, but enabled the photosensitivity of titanium dioxide for absorption spectrum to larger wavelengths, in the visible spectrum. Among the samples, the one containing 2 % of PCBM showed higher photocatalytic activity comparing to the sample of pure titanium dioxide, when irradiated by visible light.
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Palavras-chave
Dióxido de titânio, Semicondutor, Fotocatálise, PCBM