In the last ten years, stannates with perovskite structure have been tested as photocatalysts. In spite of the ability of perovskite materials to accommodate different cations in its structure, evaluation of doped stannates is not a common task in the photocatalysis area. In this work, Fe 3+ doped BaSnO 3 was synthesized by the modified Pechini method, with calcination between 300 and 800°C/4 h. The powder precursor was characterized by thermogravimetry after partial elimination of carbon. Characterization after the second calcination step was done by X-ray diffraction, Raman spectroscopy and UV-visible spectroscopy. Materials were tested in the photocatalytic discoloration of the Remazol Golden Yellow azo dye under UVC irradiation. Higher photocatalytic efficiency was observed under acid media. As no meaningful adsorption was observed at this condition we believe that an indirect mechanism prevails. Fe 3+ doping decreased the band gap and favored the photocatalytic reaction, which may be assigned to the formation of intermediate levels inside the band gap.
ResumoA versatilidade de materiais naturais como as argilas tem chamado a atenção para a sua aplicação em estudos científicos. Neste trabalho foi avaliado o enriquecimento dessas propriedades com a impregnação de SnO2 na superfície desse material, e seu comportamento como catalisador para a reação de transesterificação de óleo de soja. Para isso, uma bentonita foi selecionada, considerando os valores de capacidade de troca catiônica e teor de quartzo. A bentonita foi utilizada na forma pura e impregnada com SnO2 por dois métodos: solvotermal assistido por micro-ondas e Pechini modificado. Para avaliar a eficiência da impregnação, foram realizadas algumas caracterizações, como difração de raios X, adsorção de N2 e microscopia eletrônica de varredura, que mostraram uma melhor dispersão do SnO2no suporte utilizando o método Pechini modificado, o qual também apresentou melhor eficiência no teste catalítico para obtenção de biodiesel, reduzindo em 41,3% a viscosidade do óleo utilizado.
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