The photocatalytic degradation of Reactive Black 5 (RB 5), a di-azo dye was investigated over M/TiO2 (M = Ag, Au and Pt) photocatalysts irradiated with UV and visible light. TiO2 was prepared by sol–gel technique (Syn-TiO2). Photodeposition of metal salt precursors over Syn-TiO2 was carried out so as to obtain 1 wt% of M/TiO2 catalysts. The photodecolourization and photodegradation reactions were also compared with commercial TiO2 (Degussa P25) catalyst. Kinetic studies for the decolourization of RB 5 showed that it followed pseudo first order. Recycling of catalysts was performed to check the economic feasibility of the photocatalytic process. In order to check the applicability of M/TiO2 catalyst in the treatment of industrial effluent, real textile effluent was collected from an industry and subjected to photodegradation and the results are presented. Enhanced activity of M/TiO2 catalyst under visible light irradiation highlights its importance in the field of photocatalysis.

Keywords: decolourization, kinetic studies, photodegradation, photodeposition, recycling, reactive black