Non-radical mechanism of N-doped porous biochar derived from corn stalks for efficient peroxydisulfate activation

Biochar has demonstrated significant potential as an alternative to carbonaceous catalysts in peroxydisulfate (PDS) activation for the oxidation of organic pollutants. However, the catalytic performance of pristine biochar generally remains unsatisfactory due to its inert conjugated carbon framework and limited redox moieties. It is of great necessity to fabricate biochars with abundant effective sites to promote the degradation of pollutants mainly through the non-radical mechanism. Herein, corn stalk and melamine were selected as a precursor for preparing nitrogen-doped biochar (N-BC) through ball-milling and high-temperature pyrolysis under oxygen-limited conditions. Benefiting from the unique properties of nitrogen-doped biochar (N-BC), such as large specific surface area, well-formed oxygen-containing groups, and abundant structural defects, the 2,4-dichlorophenol (2,4-DCP) degradation efficiency reached 98.4% in 40 min by N-BC/PDS system. In particular, N-BC maintained excellent catalytic ability in both artificial and natural water conditions to efficiently degraded 2,4-DCP owing to its non-radical dominated degradation mechanism based on O2·-/1O2 and electrons transferring. This study will expand biochar application and provide new insights for PDS activation to promote the non-radical oxidation of organic pollutants.