High-loading cobalt single-atom activates peroxymonosulfate to efficiently degrade sulfamethoxazole via Co (IV)-oxo and sulfate radical

The problem of antibiotic contamination urgently needs to be solved. The advanced oxidation technology of peroxymonosulfate (PMS) based on single-atom activation is regarded as a promising way. However, the single-atom load is relatively low and still fails to meet the practical application. Herein, a series of high-loading metal single-atom catalysts were successfully synthesized through chelation-high-temperature calcination, and used to activate PMS for the degradation of sulfamethoxazole (SMZ). The order of catalyst activity was: Co-C 3 N 4 > Fe-C 3 N 4 > Cu-C 3 N 4 > Ni- C 3 N 4 > Zn-C 3 N 4 . SMZ could be completely removed in 30 min with a 0.0384 min −1 reaction rate constant and Escherichia coli ( E. coli ) was completely inactivated in Co-C 3 N 4 + PMS system. The main active species was high-valent Co (IV)-oxo and sulfate radical. The degradation pathway of SMZ was explored by three-dimensional fluorescence and liquid chromatography-mass spectrometry. The toxicity of intermediate products was evaluated through E. coli incubation, carrot seed germination and model prediction. After degradation, the toxicity of SMZ was significantly reduced. The practical application potential of the Co-C 3 N 4 + PMS system was evaluated by continuous flow experiments. After 36 h of continuous reaction, the removal rate of SMZ could still reach 43.4%. This work confirms that a high content metal single-atom catalyst activates PMS for the degradation of organic matter.