THE COMBINATION OF OZONE WITH ULTRASOUND OR HYDROGEN PEROXIDE FOR THE DEGRADATION OF CI ACID ORANGE 7

The effect of various operating conditions on the degradation of C.I. Acid Orange 7 by ozone, combined with ultrasound (US/O-3) or hydrogen peroxide (H2O2/O-3), was investigated. The decolorization of C.I. Acid Orange 7 fits the pseudo-half-order kinetic model in H2O2/O-3 system. The rate constant increased with the increase of pH, hydrogen peroxide concentration, and gas flow rate. The presence of carbonate inhibited the decolorization rate, and the rate constant decreased with increasing carbonate dosage as well as initial dye concentration. The combination of ozone with hydrogen peroxide achieved a higher COD removal efficiency than ozonation alone. The synergistic effect of C.I. Acid Orange 7 mineralization by sonolytic ozonation was also significant when the system temperature was raised due to the heat effect of ultrasonic irradiation. The increase of ultrasonic power and gas flow rate would lead to the increase of TOC removal rate by the combined US/O-3 system. Initial pH has little effect on TOC removal. The presence of sodium carbonate would improve TOC removal when sodium carbonate to dye molar ratio investigated was not higher than 10.