Efficient catalytic ozonation over CuO/ZnO for ofloxacin degradation: the synergistic effect between CuO and ZnO promotes the catalytic effect

ABSTRACT In this study, zinc oxide (ZnO) supported copper oxide (CuO) catalyst was prepared and characterized. Ofloxacin (OFL) was selected as the target pollutant to study the catalytic activity of CuO/ ZnO. The characterizations of CuO/ZnO were studied using X-ray diffraction, field emission scanning electron microscopy and X-ray photoelectron spectroscopy etc. The catalytic activity of CuO/ZnO on OFL degradation efficiency was systematically examined under different experimental conditions: including different catalyst doses, O 3 flow rates, initial pH values and OFL concentrations. The catalytic activity achieved maximal when Cu:Zn was 1:5. The results showed that the degradation of OFL increased with the increase of CuO/ZnO dosage, O 3 flow rate and pH value, but decreased with the increase of OFL initial concentration. Under selected initial conditions (80 mL/min ozone flow, 20 mg/L OFL solution, and 0.63 g/L catalyst dosage), the O 3 +CuO/ZnO process significantly improved OFL removal efficiency due to the production of hydroxyl radical ( • OH), which was approved by tert-butanol (TBA). It was confirmed that CuO and ZnO showed synergistic effect on the catalytic ozonation of OFL. The degradation efficiency of OFL was only slightly decreased after five repeated times, indicating that CuO/ZnO had well catalytic stability.