Degradation of sulfamethoxazole by cobalt-nickel powder composite catalyst coupled with peroxymonosulfate: Performance, degradation pathways and mechanistic consideration

In this work, cobalt-nickel powder (Co-NP) synthesized through electroless plating was used as a heterogeneous bimetallic catalyst for peroxymonosulfate (PMS) activation to degrade sulfamethoxazole (SMX) in the aqueous phase. Compared with different oxidation systems and different catalysts, it was proved that Co-NP had excellent catalytic ability, fast electron transfer rate and good stability. The effects of key parameters (initial pH, SMX concentration, catalyst and PMS dosages) on SMX degradation and ion leaching were studied in detail. Furthermore, the sensitivity of inorganic anions and different pollutants towards the Co-NP/PMS system was studied to investigate its application in natural water bodies. Quenching test showed that the main reactive oxygen species generated during the reaction were (OH)-O-center dot and SO4 center dot-, of which SO4 center dot- played a predominating role. Combined with XPS analysis, the activation mechanism was concluded that free radicals were mainly generated through the valence change of Co and Ni. Based on the seven intermediates measured through ultrahigh performance liquid chromatograph-mass spectrometry (UPLC-QTOF-MS/MS), the possible degradation pathways of SMX were proposed. Notably, this study provided a new kind of supporter for advanced oxidation processes and electroless plating technology.