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

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.