Enhanced sulfamethoxazole ozonation by noble metal-free catalysis based on magnetic Fe₃O₄ nanoparticles: Catalytic performance and degradation mechanism

In this research, Fe₃O₄ nanoparticles were prepared by a low-cost route free of other agents, and applied in the catalysis of sulfamethoxazole (SMX) ozonation. It was proven that Fe₃O₄ nanoparticles significantly enhance SMX ozonation. Using a kinetics analysis, when Fe₃O₄ particles were added to the ozonation process, the reaction rate constant increased by 51% when the pH was 5. Moreover, we also identified that Fe₃O₄ enhanced the SMX ozonation removal rate by changing the degradation pathway. It was found that addition of Fe₃O₄ improved the production of Lewis acid active sites in SMX. These kinds of site in SMX are much easier to attack, which leads to a higher SMX removal rate and lower operational costs for the Fe₃O₄-based catalytic ozonation process compared to an O₃ oxidation process. Finally, the SMX degradation pathways were classified for the first time, based on ozone oxidation types to give a guide for the quick and direct oxidation of SMX and other pollutants.