Boron and nitrogen hydrothermal co-doped sludge biochar towards efficiently activate peroxymonosulfate for sulfamethoxazole degradation

Designing efficient catalyst for peroxymonosulfate (PMS) activation is beneficial for eliminating the adverse effects of sulfamethoxazole (SMX) on human health. A novel boron (B) and nitrogen (N) co-doped sludge biochar (BNSBC) was synthesized by one-pot hydrothermal activation, and its remarkable PMS activation performance facilitated the rapid elimination of SMX from water. The degradation rate of SMX by BNSBC/PMS system could reach 92.1% within 60 min ([SMX] 0 = 10 mg/L, [BNSBC] 0 = 0.4 g/L, [PMS] 0 = 1 mM). B and N exhibited the synergistic enhancement effects on the physico-chemical characteristics of SBC, and abundant pores, defects, C O, -O-B-O-, graphitic-N and pyridinic N were confirmed as the main active sites of BNSBC for PMS activation. Characterization, quenching, electron paramagnetic resonance (EPR) and electrochemical tests proved that non-radicals of surface-bound, 1 O 2 and electron transfer were the main contributors to SMX degradation. The high anti-interference of BNSBC/PMS system to pH range, co-existing inorganic anions and organic matter guaranteed its outstanding purification performance for SMX in diverse environmental waters. Four potential degradation pathways of SMX in BNSBC/PMS system were proposed by its intermediates identification and density functional theory (DFT) calculation, and pathway Ⅳ was the main one. The toxicity levels of its intermediates were lower than that of SMX regardless of chronic and acute toxicity . Also, BNSBC/PMS system exhibited the board-spectrum removal performance for other typical antibiotics (e.g., sulfadiazine (SDZ), sulfamethoxypyridazine (SMP), ciprofloxacin (CIP), tetracycline (TC)). BNSBC/PMS has great application potential for eliminating diverse antibiotics in actual wastewater due to its high tolerance to complex environmental conditions and outstanding detoxification ability, also it offers a harmless disposal approach for sludge.