Reactive azo dyes are among the most applicable dyes n textile industries. However, these compounds are environmentallyhazardous and difficult to treat by classical ethods. In the present study a batch stirred photoreactor with a novel irradiating setup was utilized for decolorization of a reactive azo dye. The effects of certain parameters including initial dye, H2O2 concentration, photocatalyst loading and initial pH in a system consisting of UV/TiO2/ H2O2 on the decolorization and degradation of C.I. Reactive Black 8 were investigated. Box-Behnken method, a statistical experimental design method, has been used to optimize the decolorization process. Decolorization efficiency increases with decreasing initial dye concentration,addition of H2O2 up to an optimum value, increasing photocatalyst loading and at original pH values (containing nopH adjusting chemicals).The optimum parameters for decolorization of ReactiveBlack 8 are obtained as follows: TiO2 = 1.59 g L-1, ReactiveBlack 8 concentration =34.65 ppm, pH = 5.5, H2O2concentration = 1.82 (stoichiometric ratio). By use of theseoptimum parameters 96.1% decolorization and 78.6% degradation of the dye in the solution was observed within 60minutes irradiation
