Peroxymonosulfate activation via CoP nanoparticles confined in nitrogen-doped porous carbon for enhanced degradation of sulfamethoxazole in wastewater with high salinity

Transition-metal phosphides (TMPs) have been considered a promising candidate for heterogeneous catalysis in wastewater treatment, while the feasibility of its application in peroxymonosulfate (PMS) based advanced oxidation processes systems for the treatment of high-salinity organic wastewater remains still unclear. In this study, catalysts of cobalt phosphide (CoP) nanoparticles confined in nitrogen-doped porous carbon (CoP/NC) were prepared using zeolitic imidazolate framework-67 (ZIF-67) as a template via calcination-oxidationphosphorization, which were subsequently applied to activate peroxymonosulfate (PMS) for the degradation of sulfamethoxazole (SMX) in the water with high-salinity concentrations. Results showed that the degrading performance of CoP/NC could be improved and regulated by phosphorus (P) doping amount with an optimum of 5.0% (CoP/NC-5), which reached 100% of SMX degradation. Meanwhile, CoP/NC-5 catalyst could tolerate wide pH variations (5-9). More importantly, the CoP/NC-5/PMS system showed high adaptability to various concentrations of inorganic salt, even up to 500 mM. In addition, active species of sulfate radical (SO4 center dot-) and singlet oxygen (O-1(2)) were identified, which played dominant roles in the destruction of SMX, and the production amount of SO4 center dot- was quantified. This work confirmed that transition-metal phosphides nanoparticles confined in nitrogen-doped porous carbon were a promising catalyst for SMX elimination in high saline wastewater.

Automated summary

This study investigated the application of cobalt phosphide nanoparticles confined in nitrogen-doped porous carbon for the degradation of sulfamethoxazole in high-salinity wastewater. The results showed that the catalyst could achieve 100% degradation with optimal phosphorus doping amount. The catalyst also exhibited high adaptability to wide pH variations and various concentrations of inorganic salt. Active species of sulfate radical and singlet oxygen were identified, which dominated the degradation process.