Photocatalytic Decolorization of Red Dye in Aqueous ZnO-TiO₂ Suspensions

Abstract:

The photocatalytic decolorization of aqueous solutions of Direct Red 27 in the presence of various amounts of semiconductor powder suspensions has been investigated in a batch reactor with the use of artificial light sources. ZnO and TiO2 have been found the most active photocatalysts; the effect of catalyst loading and type on the reaction rate was optimized for maximum degradation. The results imply that 1:1 ratio is proper for the photocatalytic removal of Direct Red 27. In addition, the effects of particle size and surface area were examined in this photocatalytic process. The results showed that the decolorization efficiency increases with increase in surface area, and decrease in powder size. The efficiency is related to mechanism of reactions on the active sites of the catalyst surface and broad adsorption of compounds with different band gaps