The effect of operational parameters on the photoinduced decoloration of dyes using a hybrid catalyst V2O5/TiO2

The decoloration of three dyes namely Toludine Blue, Safranin Orange and Crystal Violet was studied in the presence of UV radiation using a heterogeneous hybrid catalyst, namely titanium oxide impregnated with vanadium oxide. The advantage of using a hybrid catalyst lies in the fact that the decoloration increased by more than five times as compared to in a neat catalyst. The influence of operational parameters, such as dye concentration, amount of catalyst and pH of the solution were thus determined for dye decoloration using a hybrid catalyst. Rate of photoinduced catalytic decoloration was calculated from the observed absorption changes and the induced effects were explained on a mechanistic model involving the generation of *OH radicals which are responsible for the decoloration of dye solution. The kinetic data fitted well to pseudo first order equation and the Langmuir-Hinshelwood model. Dye decoloration was also investigated in the presence of some ions and their role was discussed in terms of chemical reactions. (c) 2006 Elsevier B.V. All rights reserved.