O2 plasma-modified carbon nanotube for sulfamethoxazole degradation via peroxymonosulfate activation: Synergism of radical and non-radical pathways boosting water decontamination and detoxification.

Sulfamethoxazole (SMX), a widely used antibiotic, has triggered increasing attention due to its extensive detection in wastewater effluent, causing serious ecological threats. Herein, a carbon-based heterogeneous catalyst was developed by the O2 plasma-etching process, regulating oxygen-containing functional groups (OFGs) and defects of carbon nanotubes (O-CNT) to activate peroxymonosulfate (PMS) for highly efficient SMX abatement. Through adjusting the etching time, the desired active sites (i.e., C=O and defects) could be rationally created. Experiments collectively suggested that the degradation of SMX was owing to the contribution of synergism by radical (•OH (17.3%) and SO4•- (39.3%)) and non-radical pathways (1O2, 43.4%), which originated from PMS catalyzed by C=O and defects. In addition, the possible degradation products and transformation pathways of SMX in the system were inferred by combining the Fukui function calculations and the LC-MS/MS analysis. And the possible degradation pathway was effective in reducing the environmental toxicity of SMX, as evidenced by the T.E.S.T. software and the micronucleus experiment on Vicia faba root tip. Also, the catalytic system exhibited excellent performance for different antibiotics removal, such as amoxicillin (AMX), carbamazepine (CBZ) and isopropylphenazone (PRP). This study is expected to provide an alternative strategy for antibiotics removal in water decontamination and detoxification.