Radical/non-radicals oxidative degradation of sulfamethoxazole via peroxymonosulfate activation by ball milling and N-doping co-functionalized sludge biochar

Developing an efficient activator for peroxymonosulfate (PMS) is of great significance for eliminating emerging contaminants (e.g., antibiotics such as sulfamethoxazole (SMX)) from water. A novel ball milling and nitrogendoping (melamine was used as the nitrogen source) co-functionalized sludge biochar (BMNSBC) was the first time synthesized and employed to activate PMS for oxidative degradation of SMX. The removal rate of SMX could reach up to 100 % within 60 min (C0(SMX) = 10 mg/L, (BMNSBC)0 = 0.4 g/L, and C0(PMS) = 1 mM). The defective structure and pyridinic-N were confirmed as the main catalytic sites of BMNSBC. Combined with quenching experiments, electron paramagnetic resonance (EPR) analysis and electrochemical experiments, it suggested that both radical (center dot OH) and non-radicals (1O2, surface-bound and electron transfer) contributed to SMX degradation in PMS/BMNSBC system. In addition, BMNSBC exhibited outstanding sustainable catalytic degradation performance for SMX even after five reuse cycles. Compared with SMX, the transformed products (TPs) generated in PMS/BMNSBC system were less toxic to typical aquatic organisms (daphnia, green algae and fish). Also, PMS/BMNSBC system built in this study was capable of efficiently degrading SMX in various actual waters including pure water (90.1 %), tap water (75.89 %), river water (75.79 %) and lake water (73.8 %). The high tolerance, outstanding degradation/detoxification ability and low ecological risk of PMS/BMNSBC system enabled it to be a prospective technique for antibiotics elimination, as well as resource utilization of municipal sludge.