Ultrasound-heterogeneous catalytic oxidation of phenol in aqueous solutions

The degradation of phenol is investigated in the presence of ultrasound/H2O2/CuO, ul-trasound/H2O2/Ni2O3 and ultrasound/H2O2/MnO2 systems. The initial concentration of 25 mg/L phenol is selected as model pollutant aqueous and the catalytic oxidation is carried out in a jacketed beaker. Under the conditions of ultrasound intensity 4.97 W/cm, H2O2 initial concentration 300 mg/L, catalyst dosage 1 g/L and the temperature 30°C, the higher efficency of phenol degradation can be achieved in ultrasound/H2O2/CuO compared with other catalytic systems. The removal ratio of phenol is 24.0%, 53.3%, 13.8% and 89.5% respectively corresponding to ultrasound, ultrasound/H2O2, CuO/H2O2 and ultrasound/H2O2/CuO treatment systems with the ultrasound irradiation 240 min. It is indicated that ultrasound, H2O2 and CuO have synergistic effect. When the temperature increases from 20°C to 50°C, the phenol removal ratio increases apparently under the three kinds of systems, therefore, the enhanced degradation of phenol can be ascribed to catalytic effect instead of ultrasonic effect.