Removal of chloramphenicol in water by an improved water falling film dielectric barrier discharge reactor: Performance, mechanism, degradation pathway and toxicity evaluation

Chloramphenicol (CAP) is a common antibiotic, which is difficult to be removed in water environment and has caused huge environmental risks. Herein, an improved water falling film dielectric barrier discharge (WFFDBD) reactor was built to treat 20 L of CAP wastewater. The effects of operating parameters of the reactor on CAP degradation were investigated, the main reactive species for CAP degradation were identified, the intermediates and degradation pathway of CAP were analyzed, and the toxicity of degradation products of CAP was evaluated by quantitative structure activity relationship (QSAR) models. The results show that CAP degradation efficiency was significantly increased by covering medical gauze. At 370 W of discharge power, CAP degradation efficiency was 88.7% and 59.9% after 140 min treatment with and without the gauze, and the energy efficiency of WFFDBD reactor with medical gauze was 2.53 times higher than that without medical gauze. The medical gauze significantly increased the yield of the reactive species of WFFDBD. Correlation matrix analysis showed that the contribution of H2O2, O3 and ·OH for CAP removal followed the order of ·OH > H2O2> O3. Moreover, O2⋅− and ·H were also the key species for CAP degradation. A possible degradation pathway was given based on the measured degradation products. The developmental toxicity of CAP and its degradation products were quantified, and the results indicate the toxicity of CAP wastewater was weakened after WFFDBD treatment. [Display omitted] •Uniformity of water film of WFFDBD reactor was improved by covering medical gauze.•OH, O3, H2O2, O2⋅− and ·H contributed to CAP degradation.•Both oxidation and reduction reactions involved in CAP degradation.•Correlation matrix was used to evaluate the contribution of O3, H2O2 and ·OH for CAP removal.•Developmental toxicity of CAP was weakened after WFFDBD.