Insight into nitrogen-doped biochar prepared from Chinese medicine compound residue for peracetic acid activation in sulfamethoxazole degradation: Electron transfer mechanism

The advanced oxidation system based on peracetic acid (PAA) has been proved to be a green and safe oxidation decontamination technology. Among them, the key challenge and complexity in current research lies in the directional induction of PAA and its utilization for selective removal of refractory pollutants. This study prepared nitrogen-doped biochar (NBC) using compound pharmaceutical residues commonly found in traditional Chinese medicine as a precursor. A system based on NBC-activated PAA was constructed for sulfamethoxazole (SMX) degradation. The introduction of nitrogen significantly enhanced the degree of graphitization in NBC. The degradation system achieved 87.89 % SMX degradation efficiency within 60 min. Furthermore, the formation of the intricate NBC-PAA* complex detected by in-situ Raman was of paramount importance as it facilitates enhanced electron transfer processes within the complex, thereby promoting PAA decomposition through electron loss. The formation of a new complex between SMX and NBC-PAA* facilitated the completion of electron transfer process within the complex. In summary, this study explored a novel approach for treating and disposing of solid waste from Chinese medicine residue by successfully inducing non-free radical degradation pathway using PAA system. It offers fresh insights and ideas in the fields of water treatment and solid waste management.