The effect of operational parameters and TiO2-doping on the photocatalyticdegradation of azo-dyes

The photocatalytic degradation of Acid Orange 7 (AO7), a non-biodegradable ate-dye, has been investigated over TiO2 photocatalysts irradiated with a l ight source simulating solar light. The effect of operational parameters, i .e., dye concentration, photocatalyst content, pH of the solution and incid ent light energy on the degradation rate of aqueous solutions of AO7 has be en examined. The effect of incorporating cations with valence higher (W6+) and lower (Ca2+) than the parent cation (Ti4+) in the TiO2 matrix has also been investigated. Results show that the employment of efficient photocatal ysts and the selection of optimal operational parameters may lead to comple te decolorization and to substantial decrease of the Chemical Oxygen Demand (COD) of the dye solutions. (C) 1999 Elsevier Science B.V. All rights rese rved.