Evaluation of Nb2O5 and Ag/Nb2O5 in the photocatalytic degradation of dyes from textile industries

The textile industries are distinguished by the use of dyes that are applied to textiles. Dyes are pollutant materials that are difficult to decompose by microbiological treatment. An alternative way to prevent contamination of the environment by dyes is the oxidation of these materials through photocatalysis, a process by which illumination of an oxide semiconductor produces photoexcited electrons and cations that migrate over the surface of the oxide, effectively participating in the chemical reaction. The purpose of this work is to synthesize catalysts and study their performance in the photocatalytic degradation of dyes. Niobium pentoxide and silver oxide supported on niobium pentoxide (Ag/Nb2O5), prepared by the impregnation method, were used as catalysts. Prior to use the catalysts were submitted to thermal treatment for drying and calcination. Drying was carried out at 150degreesC for 12 hours and then the solids were calcined at 500degreesC for 5 hours. After that the catalysts were applied in the photocatalytic degradation of different types of dyes from textile industries. Discoloration tests were carried out in a photocatalytic reaction unit during a period of 24 hours under different operational conditions in the presence and absence of ultraviolet light (UV). The results, evaluated by spectrophotometry, show that photodegradation of the dyes occurs, which allows evaluation of the influence of the silver on photocatalytic degradation.