Chemical inertness conversion of carbon fraction in coal gangue via N-doping for efficient benzo(a)pyrene degradation

Efficient degradation of organic pollutants in complex media via advanced oxidation processes (AOPs) is still critical and challenging. Herein, nitrogen (N)-doped coal gangue (CG) catalysts ( N -CG) with economic competitiveness and environmental friendliness were successfully synthesized to activate peroxymonosulfate (PMS), exhibiting ultrafast degradation performance toward benzo(a)pyrene (BaP) with 100.00 % and 93.21 % in contaminated solution and soil under optimized condition, respectively. In addition, 0.4  N -CG possessed excellent reusability toward BaP degradation with over 80.00 % after five cycles. However, BaP removal efficiency was significantly affected by some co-existing anions (HCO 3 − and SO 4 2− ) and humic acid (HA) in solution and soil, as well as inhibited under alkaline conditions, especially pH ≥ 9. According to the characterizations, N -doping could promote the generation of pyridinic N and graphitic N in N -CG via high-temperature calcination, which was conducive to produce hydroxyl radical ( • OH), sulfate radical (SO 4 •− ), superoxide radical ( • O 2 − ) and single oxygen ( 1 O 2 ). In 0.4  N -CG/PMS system, 1 O 2 and • O 2 − were proved to be the predominant reactive oxygen species (ROSs) in BaP degradation, as well as • OH and SO 4 •− made certain contributions. To sum up, this work provided a promising strategy for synthesis of CG-based catalysts by chemical inertness conversion of carbon fracture via N -doping for PMS activation and opened a novel perspective for environmental remediation of hydrophobic and hydrophilic contaminants pollution.