Cu/N co-doped biochar activating PMS for selective degrading paracetamol via a non-radical pathway dominated by singlet oxygen and electron transfer.

The non-free radical oxidation pathway (PMS-NOPs) of peroxymonosulfate (PMS) holds significant promise for practical wastewater treatment applications, owing to its low oxidation potential, high PMS utilization rate, and robust anti-interference capability in the degradation of pollutants. A novel activator copper nitrogen co-doped porous biochar (Cu-N-BC) with rich defect edges and functional groups was obtained by adding Cu and N to the biochar matrix generated by sodium alginate through pyrolysis in this study. Under the condition of 1 mM PMS, 30 mg/L activator was used to activate PMS and achieve efficient degradation of 10 mg/L paracetamol (PCT) within 15 min, with a high reaction rate constants (k obs) of 0.391 min−1. The activation mechanism of the Cu-N-BC/PMS/PCT system was a non-radical activation pathway with the dominance of singlet oxygen (1O 2) and the presence of catalyst-mediated electron transfer. The graphite nitrogen, pyridine nitrogen, and Cu–N coordination introduced by Cu/N co-doping, as well as the carbon skeleton and C O functional group of biochar, were considered active sites that promote the 1O 2 generation. The Cu-N-BC/PMS system exhibits strong stability, eco-friendliness, effective mineralization, and interference resistance across diverse pH levels (3–11) and interfering ions, including Cl−, H 2 PO 4 −, NO 3 −, SO 4 2−, and humic acid. Remarkably, it efficiently degrades PCT in tap and lake water, achieving a notable 63.73% TOC mineralization rate, with leached copper ions below 0.02 mg/L. This research introduces a novel method for obtaining metal nitrogen carbon activators and enhances understanding of PMS non-radical activation pathways and active sites. [Display omitted] • A strategy of co-doping biochar was developed to construct a non-radical activation mechanism of PMS. • The degradation efficiency of paracetamol can reach 100% with low-dose activators. • Singlet oxygen and electron transfer were responsible for the degradation. [ABSTRACT FROM AUTHOR]