Estudo de fotodegradação de efluente sintético composto pelos corantes alimentícios, vermelho 40 e azul brilhante, utilizando radiação ultravioleta

Abstract

The food industry uses in its processes a large quantity of dyes, which in turn makes the efluent colored, causing interference in photosynthetic processes. Due to the great concentrations of organic matter and their strong colorations, these effluents are important sources of pollution of the water bodies, being able to cause alterations in the aquatic biota, mainly in the vicinity of the launching point. In this work the photodegradation process using ultraviolet radiation, aqueous solutions of the red food colorant 40 and later the synthetic effluent composed of red 40 and bright blue dyes, was evaluated through the following variables: irradiation time, solution concentration and pH, in the absence and presence of photocatalyst. The quantification of dyes in solutions, before and after the photodegradation, was done with the use of UV/Vis spectroscopy. The results show that this methodology was satisfactory in the total discoloration of the solutions in concentrations of 10, 15 and 20 mg/L, and relatively short times are necessary for this purpose. In addition, the study of irradiation of the samples as a function of pH showed a dependence of this process with this parameter, obtaining a better result for pH 12. In the study carried out with the TiO2 photocatalyst a significant increase was observed in the degradation rate of the effluent synthetic. It was also observed that there was a decrease in the absorption bands of the ultraviolet region, in addition to the appearance of other bands, which shows that the processes of direct photolysis and photocatalysis happened without the formation of sub products.