Degradation of dichloroacetic acid in acidic solution by nanosized ZnO catalyzed ozonation

Nanosized ZnO catalysts prepared by the precipitation method were used for the degradation of dichloroacetic acid (DCAA) in acidic solution by ozone. Catalyst samples were characterized by measuring the specific area (BET) and X-ray diffraction (XRD). The results showed that the presence of ZnO catalyst obviously improved the degradation efficiency of DCAA in the process of ozonation, 67.9% higher compared with ozonation alone, and operating parameters such as catalyst loading, gas ozone concentration and pH exerted a positive influence on the DCAA catalytic degradation under the same experimental conditions. 25 mg/L of tert-butyl alcohol (t-BuOH) in the aqueous bulk leaded to significant reduction of 67.6% for the degradation efficiency of DCAA in the ZnO catalytic ozonation, indicating that ZnO catalytic ozonation followed a hydroxyl radical (•OH) reaction mechanism. According to the experimental results, it was suggested that nanosized ZnO catalyst exhibited efficient catalytic properties for the acceleration of ozone decomposition and the generation of •OH, resulting in the enhancement of degradation efficiency of DCAA.