Nitrogen and sulfur co-doped mesoporous carbon as an efficient peracetic acid activator for the degradation of 4-chlorophenol: A nonradical mechanism dominated by singlet oxygen

Abstract

Metal-free peracetic acid (PAA) activators are urgently required due to their low toxicity. Heteroatom doping is beneficial to improve the catalytic performance of carbon materials, but the activation performance of doped carbon materials on PAA and the underlying mechanism have not been reported. Herein, nitrogen and sulfur co-doped mesoporous carbons (NS-MC-x, with x representing the mass ratio of thiourea:mesoporous carbon) were fabricated and used as efficient PAA activators for 4-chlorophenol (4-CP) degradation. The NS-MC-1.0/PAA system can remove > 95 % of 4-CP within 10 min, far more than the MC/PAA system. Co-existing anions show no effect on the degradation of 4-CP, whereas humic acid has a certain degree of inhibition. Singlet oxygen (1O2) primarily drives the degradation of 4-CP, with a secondary contribution from a direct electron transfer process mediated by reactive surface complexes, while the contribution of radicals is minimal. In addition, NS-MC-1.0 exhibits excellent reusability for PAA activation, which is conductive to its practical application. This study facilitates further research on metal-free catalysts for PAA activation and offers fresh perspectives on the utilization of PAA in degrading emerging pollutants.