Desempenho do compósito fotocatalisador TiO2/Ftalocianina de zinco, visando sua aplicação em fotocatálise solar

Abstract

The present study sought to compare the performance of a composite based on association between the TiO2 P25 and zinc phthalocyanine (TiO2/FtZn 1.6%), and TiO2 P25 in the photocatalytic degradation and mineralization of the dye Ponceau 4R (C.I. 16255), P4R. The result in laboratory scale presented by composite, in the absence of hydrogen peroxide, is about three times higher than that presented by TiO2 P25, resulting in 50% of mineralization dye after 120 minutes of reaction. This performance has been attributed to the synergy between zinc phthalocyanine aggregates and the surface of the catalyst. Additional studies conducted in laboratory scale to define the most appropriate concentration of hydrogen peroxide to accelerate the mineralization of P4R, were made using just the composite. It was observed that when a concentration of 0.1 mL/L (9.7 x 10-4 M or 33 mg of H2O2 per litre of solution) in terms of H2O2 was used, the performance of the reaction was improved. The role of the pH of the medium on the degradation and mineralization of P4R, promoted by the composite and also by TiO2 P25, was also evaluated. To P4R degradation, pH showed no significant effect. However, for mineralization the best performance occurred at pH 6.0 in both cases. Photocatalytic tests on a large scale, made under action of solar radiation using a CPC (Compound Parabolic Collector) reactor under the best conditions of pH and concentration of H2O2, defined in laboratory scale, reinforce the higher efficiency of the composite TiO2/FtZn 1.6%.