Peroxymonosulfate Activation by Fe/C Composites for Paracetamol Degradation: Performance Evaluation and Mechanism Insight

Peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) relying on non-radical pathways offer advantages such as resistance to interference, efficient oxidant utilization, and selective degradation of pollutants. In this study, an Fe, N co-doped activator (Fe-N-C_1.5) was synthesized using a simple mixed solvent pyrolysis method. The Fe-N-C_1.5 exhibited excellent PMS activation activity. A total of 100% of paracetamol (PCT, 10 ppm) was degraded in the Fe-N-C_1.5/PMS system in 7 min. Furthermore, this oxidation system maintained effective PCT removal even in the presence of background ions and in real water matrices. In addition, the leached Fe concentration after 60 min was only 0.084 mg/L, and 94% of PCT could still be removed during the fourth cyclic use of the catalyst. Quenching experiments, electron paramagnetic resonance (EPR), and electrochemical analysis revealed that the Fe-N-C_1.5/PMS/PCT system predominantly relies on non-radical pathways, including singlet oxygen (¹O₂) and catalyst-interface-mediated electron transfer process (ETP). X-ray photoelectron spectroscopy (XPS) analysis and KSCN toxicity experiment confirmed that the graphitic N, carbonyl (C=O), and Fe-N_x were the main PMS activation sites. This study provides an understanding of degradation mechanisms of the Fe-N-C_1.5/PMS/PCT system and offers insights into the design of iron–carbon composite catalysts that carry out non-radical PMS activation.