Tailoring lignocellulose-derived biochar for peroxymonosulfate-based catalytic environments: Optimizing active sites, revealing activation mechanisms, and advancing groundwater remediation applications.

Biochar derived from lignocellulosic biomass (LB) has shown broad application prospects in the field of peroxymonosulfate (PMS) catalysis, but the regulation mechanism of its catalytic active sites (e.g., C=O group) and LB components (cellulose, hemicellulose, and lignin) remains to be systematically elucidated. In this study, a laccase-mediated directional regulation strategy of LB components was innovatively proposed to target the design of biochar rich in the C=O group. Using wheat straw (WS) as a model feedstock, the properties and performance of biochar derived from native WS (BC-WS) and laccase-pretreated WS residue (BC-LR) were compared. Laccase pretreatment significantly enhanced the C=O group content of BC-LR by 213 %, achieved through a 27 % reduction in the relative lignin content and a corresponding increase in cellulose proportion. BC-LR demonstrated superior catalytic activity and reactive oxygen species yield than BC-WS in PMS activation, with strong positive correlations observed between its C=O content and phenol degradation kinetics (R=0.9145) as well as PMS decomposition kinetics (R=0.9957). Mechanistic investigations revealed that C=O-mediated non-radical pathway (including O and surface electron transfer) and adsorbed carbon transfer pathway dominated the phenol removal process in the BC-LR/PMS system. Notably, the BC-LR/PMS system exhibited broad-spectrum degradation of typical pollutants such as bisphenol F, o-phenylphenol, and naproxen. In addition, the system exhibited robust performance in dynamic remediation experiments under diverse hydrogeological conditions, achieving high efficiency in complex environments. This study elucidates the critical role of LB components in determining the C=O content and catalytic performance of biochar, providing a foundation for the tailored design of high-performance biochar for PMS catalytic environments.