Functional biochar accelerates peroxymonosulfate activation for organic contaminant degradation via the specific B-C-N configuration.

Functional biochar designed with heteroatom doping facilitates the activation of peroxymonosulfate (PMS), triggering both radical and non-radical systems and thus augmenting pollutant degradation efficiency. A sequence of functional biochar, derived from hyperaccumulator (Sedum alfredii) residues, was synthesized via sequential doping with boron and nitrogen. The SABC-B@N-2 exhibited outstanding catalytic effectiveness in activating PMS to degrade the model pollutant, acid orange 7 (K = 0.0655 min), which was 6.75 times more active than the pristine biochar and achieved notable mineralization efficiency (71.98%) at reduced PMS concentration (0.1 mM). Relative contribution evaluations, using steady-state concentrations combined with electrochemical and in situ Raman analyses, reveal that co-doping with boron and nitrogen alters the reaction pathway, transitioning from PMS activation through multiple reactive oxygen species (ROSs) to a predominantly non-radical process facilitated by electron transfer. Moreover, the previously misunderstood concept that singlet oxygen (O) plays a central role in the degradation of AO7 has been clarified. Correlation analysis and density functional theory calculations indicate that the distinct BCN configuration, featuring the BCO group and pyridinic-N, is fundamental to the active site. This research substantially advances the sustainability of phytoremediation by offering a viable methodology to synthesize highly catalytic functional biochar utilizing hyperaccumulator residues.