Effective degradation of quinoline by catalytic ozonation with MnCexOy catalysts: performance and mechanism

View large Download slide View large Download slide Close modal Quinoline inevitably remains in the effluent of coking wastewater treatment plants due to its bio-refractory nature, which might cause unfavorable effects on human and ecological environments. In this study, MnCe x O y was consciously synthesized by α -MnO 2 doped with Ce 3+ (Ce:Mn = 1:10) and employed as the ozonation catalyst for quinoline degradation. After that, the removal efficiency and mechanism of quinoline were systematically analyzed by characterizing the physicochemical properties of MnCe x O y , investigating free radicals and monitoring the solution pH. Results indicated that the removal rate of quinoline was greatly improved by the prepared MnCe x O y catalyst. Specifically, the removal efficiencies of quinoline could be 93.73, 62.57 and 43.76%, corresponding to MnCe x O y , α -MnO 2 and single ozonation systems, respectively. The radical scavenging tests demonstrated that • OH and • O 2 - were the dominant reactive oxygen species in the MnCe x O y ozonation system. Meanwhile, the contribution levels of • OH and • O 2 - to quinoline degradation were about 42 and 35%, respectively. The abundant surface hydroxyl groups and oxygen vacancies of the MnCe x O y catalyst were two important factors for decomposing molecular O 3 into more • OH and • O 2 - . This study could provide scientific support for the application of the MnCe x O y /O 3 system in degrading quinoline in bio-treated coking wastewater. MnCe x O y Ce 3+ , MnCe x O y • OH and • O 2 - MnCe x O y were successfully synthesized by α-MnO 2 doped with Ce 3+ . The by abundant oxygen vacancies and surface hydroxyl groups of the MnCe x O y catalyst enhanced its catalytic activity. • OH and • O 2 - formation contributed to quinoline degradation in the MnCe x O y ozonation system.