Abstract
This paper deals with the photocatalytic decolourization kinetics of a xanthene dye derivative, Phloxine B ( PhB) in aqueous suspension of TiO2 using UV light under a variety of conditions. The efficiency of different TiO2 photocatalysts such as PC500-Milennium, UV100-Hombikat and P25-Degussa were compared for the decolourization of PhB. Photocatalytic, photolytic, and adsorption experiments were performed, showing that adsorption of PhB on TiO2-UV100 is appreciable compared to that on P25 and favourable by the Langmuir approach. The effects of various operational parameters such as catalyst loading, substrate concentration of the dye, initial pH and electron acceptors such as H2O2, KBrO3 and KIO3 on the decolourization have been investigated. Under the operating conditions of this study, the photocatalytic decolourization of PhB followed pseudo first-order kinetics. The photo decolourization kinetics was discussed in terms of Langmuir-Hinshelwood kinetic model. The decolourization efficiency was found to increase with the pH at strong acidic to weak acidic ranges; however the reaction was gradually retarded at the alkaline medium due to the effect of charge repulsion.