Photochemical degradation of the hazardous dye Safranin-T using TiO 2 catalyst

Abstract

Aqueous solutions of Safranin-T, a hazardous textile dye, are photodegraded under ultraviolet light using TiO 2 as catalyst. The process has been carried out at different pHs, amounts of catalyst, concentrations of the dye, and effects of the electron acceptor H 2O 2. It is found that under the influence of TiO 2 as catalyst the colored solution of the dye Safranin-T becomes colorless and the process follows first-order reaction kinetics. The optimum conditions for the degradation of the dye have been found as 5.0 × 10 −5 M dye concentration, pH 5.7, and 12 mg catalyst dose. In order to evaluate the effect of the electron acceptor, the effect of H 2O 2 on the degradation process is also monitored and it is found that generation of hydroxyl radicals and retardation of electron–hole recombination takes place. Measuring chemical oxygen demand also monitors the toxicity of the degraded dye solution and a significant decrease is observed, which implies that the photodegradation through TiO 2 is a safer technique.