Efficient degradation of p-chlorophenol by N,S-codoped biochar activated perxymonosulfate

The easy preparation of low-cost, highly active, and environment-friendly carbon-based catalysts for wastewater treatment remains a challenge. In this study, we fabricated a biochar codoped with nitrogen and sulfur (NS-BC) as a low-cost and efficient catalyst for peroxymonosulfate (PMS) activation and p-chlorophenol degradation. NS -BC was synthesized by the pyrolysis of sawdust with urea and sulfur powder serving as the nitrogen source and sulfur source, respectively. Due to the large surface area and high defect degree of NS-BC, its catalysis performance for PMS (K-obs=0.8104) was better than those of single-doped (K-obs=0.4177 and K-obs=0.3132) and undoped (K-obs=0.1265) biochar, and it can completely degrade p-chlorophenol within 5 min. The main active substances in the activation process of PMS were elucidated by free radical burst experiments and electron paramagnetic resonance analysis. Superoxide radical and singlet oxygen were the main active species of the system. These catalysts achieve rapid removal of a wide range of organic contaminants over a wide pH range. This work mainly emphasizes that the use of nonmetal-doped biochar to activate PMS to degrade p-chlorophenol, thereby avoiding the environmental harm of metal leaching during catalyst degradation.