DEGRADATION CI REACTIVE YELLOW 81 BY US/UV/ZNO HETEROGENEOUS OXIDATION PROCESS: EFFECT OF SYSTEM PARAMETERS

The degradability of an azo dye, Reactive Yellow 81 (RY81), by heterogeneous sonophotocatalytic oxidation process was investigated using simultaneous irradiation of short wave UV-C at 254 nm and power ultrasound at 20 kHz in the presence of a heterogeneous catalyst (ZnO) in this study. The effect of various system parameters i.e. pH, ZnO dose, H2O2 and inital dye concentration was examined on the dye degradation by heterogeneous sonophotocatalytic oxidation process (US/UV/ZnO). The effect of soluble gas (N-2, O-2 and air) on the dye degradation was assessed to overcome degassing and to enhance the ultrasonic cavity formation. Dye degradation efficiency was evaluated by the abatement in the visible absorbance region. It was found that the decolorization followed non-typical pseudo-first order kinetics, characterized by stabilization of the rate to a non-zero plateau. In two hours oxidation time, almost complete decolorization and partial mineralization were accomplished at 95% and 43.5%, respectively with the rate of 0.0380 min(-1).