<b>Synergistic effect between oxides semiconductors and zeolites on photobleaching of RB250 textile dye

Resumo

The present work aims to evaluate the activity of semiconductor oxides (TiO₂, Nb₂O₅ and ZnO) supported on NaA and NaY zeolites, as well as their synergistic effect on Reactive Blue Dye (RB250) photodegradation process. Prior to deposition, TiO₂ particles size was reduced by ultrasonic scattering followed by filtration. The particles on the filtrate were used to conduct the experiments. The semiconductors were immobilized in concentrations of 2.5, 5 and 10% (w w^-1) and the photocatalytic tests were performed at catalyst concentrations of 1 and 2 g L^-1. Moreover, supported catalysts were characterized by XRD, textural analysis, zero point of charge and temperature programmed desorption of NH₃. A comparison between the supported catalysts showed high activity for the ones supported with ZnO and TiO₂. Zeolite NaY has broader opened channels than NaA, which reduces the dye molecules blockage, and, as a result, increased the catalyst activity. A higher concentration of supported catalysts (2 g L^-1) provides greater photocatalytic activity, while higher concentration of semiconductors immobilized on supports does not present significant differences.