Reaction mechanisms and toxicity evolution of Sulfamethoxazole degradation by CoFe-N doped C as Electro-Fenton cathode

As a typical sulfonamide antibiotic, sulfamethoxazole (SMX) will cause serious harm to human health and ecological environment. In this study, CoFe-N doped C was prepared as cathode catalyst of electro-Fenton for degrading SMX, and 91% of SMX could be removed within 5 h under optimum conditions (pH = 1, U = -0.7 V). In order to understand degradation mechanisms, Density Functional Theory (DFT) was combined with Liquid Chromatography-Mass Spectrometry (LC-MS), four pathways were proposed, and benzene ring fracture was the most important step. Concomitantly, the toxicity of degradation intermediates was predicted by ECOSAR software and the toxicity of most intermediates was lower than that of SMX. Therefore, this study has a certain reference value for removing the pollution of persistent organic pollutants in water.