Photocatalytic degradation of azo dye acid red 14 in water: investigation of the effect of operational parameters

Acid Red 14 (AR14), commonly used as a textile dye, could be photocatalytically degraded using TiO2 suspensions irradiated by a UV-C lamp (30 W). The experiments showed that TiO2 and UV light had a negligible effect when they were used on their own. The semi-log plot of dye concentration versus time was linear, suggesting first order reaction (K=1.41×10−2 min−1). The effects of some parameters such as pH, the amount of TiO2 and initial dye concentration were also examined. otodegradation of AR14 was enhanced by the addition of proper amount of hydrogen peroxide, but it was inhibited by ethanol. From the inhibitive effect of ethanol it was deducted that hydroxyl radicals played a significant role in the photodegradation of dye, but a direct oxidation by positive holes was probably not negligible. Accordingly, it could be stated that the complete removal of color, after selecting optimal operational parameters could be achieved in a relatively short time, about 3.5 h.