Synchronously degradation benzotriazole and elimination bromate by perovskite oxides catalytic ozonation: Performance and reaction mechanism

Abstract

Abstract Ozonation showed a good capacity on micro-emerging pollutants degradation from water or wastewater treatment, but its leading to the formation of toxic bromate. Bromate inhibition in catalytic ozonation treatment remained an important challenge. In this study, a novel catalytic ozonation was promoted using perovskite oxide as catalyst, showing good performance on synchronously degradation benzotriazole (BZA) and elimination bromate. LaCoO3 exhibited significant catalytic activity for BZA degradation, with complete degradation achieved at 15 min, and about 71% BrO3− inhibition, compared with single ozonation. LaFeO3 showed no catalytic activity for BZA degradation but inhibited the generation of BrO3− by 73%. Further investigation involving reactive oxygen species, important intermediates, the structure and surface chemical properties of the catalysts showed that H2O2 act an important effect but various in different ozonation systems. The combination of the surface hydroxyl groups on LaFeO3 with H2O2 to form [Fe-H2O2]s was found to occur in LaFeO3 catalytic ozonation, resulting the reduction of BrO3−. The production of ROS in LaCoO3 catalytic system and the cyclic of Co3+/Co2+ accelerated the BZA degradation efficiency and inhibition of BrO3−. A novel BrO3− elimination pathway was proposed, as an important contribution for the application of catalytic ozonation.