PHOTOCATALYTIC DEGRADATION OF YELLOW ALIZARIN AZO DYE IN THE PRESENCE OFTIO2SUSPENSION

The present work involves the prospects of the kinetics study for photocatalyticdecolorization of an azo dye (Alizarin yellow) in aqueous solution with TiO 2 Degussa P25 as photocatalyst in slurry form using UV-A light at 365nm.The results showed that the adsorption of alizarin yellow on TiO 2 P25 was found negligible and discoloration of this dye by TiO 2 /UV system is much faster than with direct UV photolysis. Additionally, the effects of various parameters such as initial dye concentration, catalyst dosage,H 2 O 2 concentration, addition of alcohols and presence of inorganic salts on decolorization have been investigated. The removal rate of Alizarin yellow indicated an inverse dependence on the initial dye concentration. The optimal content of the catalyst was 1 g.L -1 . The disappearance kinetics was strongly enhanced in the presence of electron acceptors such as H 2 O 2 .However,the presence in the reacting system of Cl - , SO 4 2- (Addition of dye assisting chemicals such as Cl - and SO 4 2- )inhibits the dye removal rate. The study of the effect of different type of TiO 2 on the decolorization reveals the following order of efficiency: TiO 2 - P25> TiO 2 Tiona PC.