Catalytic ozonation of sulfamethoxazole over Fe3O4/Co3O4 composites

In this study, Fe3O4/Co3O4 composites were prepared and applied in the catalytic ozonation of sulfamethoxazole (SMX). Various parameters including initial solution pH, Fe3O4/Co3O4 composites dose, O-3 dose and SMX concentration were investigated. Results showed that Fe3O4/Co3O4 composites could significantly improve the mineralization of SMX by catalytic ozonation system and a synergic effect between Fe3O4 and Co3O4 was observed. Only about 16% total organic carbon (TOC) could be removed in 60 min by single ozonation under the condition of 20 mg/L SMX, 6.0 mg/min O-3, pH 5.1 and room temperature, While in the presence of 0.10 Fe3O4/Co3O4 composites at the same conditions, 60% TOC removal were obtained by catalytic ozonation process. SMX could be degradation by O-3 rapidly and the removal was not significantly affected by the changing parameters. However, those operating parameters exerted different effects on SMX mineralization. Furthermore, the generation of hydroxyl radicals ((OH)-O-center dot) and the utilization efficiency of O-3 would increase with the addition of Fe3O4/Co3O4 composites. The quenching experiments indicated that (OH)-O-center dot might account for the enhancement of SMX mineralization and the mechanism of catalytic ozonation was proposed. Additionally, the intermediates were detected by using a high-performance liquid chromatography-mass spectrometry (LC-MS), from which some plausible transformation pathways were proposed. (C) 2019 Elsevier Ltd. All rights reserved.