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 O-3 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.