Significantly accelerated degradation of naproxen by reduction and complexation coupling in a Cu0/PMS system

Cu 0 - activated peroxymonosulfate (PMS) is a promising advanced oxidation process for the removal of pharmaceuticals and personal care products, yet its performance is often limited by inefficient Cu(II)/Cu(I) redox cycling as well as the low steady-state availability of reactive copper species. Here, we constructed a Cu 0 /HA/NCP/PMS system by integrating hydroxylamine as a reductant and neocuproine as a Cu(I) - complexing ligand to intensify naproxen degradation and investigate the underlying activation pathway. Under typical conditions, the synergistic combination of HA and NCP caused NPX removal to enable 98.57% within 6 min. This is significantly higher than those in Cu 0 /PMS, Cu 0 /NCP/PMS, and Cu 0 /HA/PMS. The system maintained high efficiency across pH 3.0 ~ 7.0. Scavenging tests and nitrobenzene probing indicated that ⋅ O H / S O 4 ⋅ − pathways were not dominant, whereas benzoic acid caused only moderate inhibition, collectively supporting a non-radical pathway. Spectroscopic and LC-MS evidence revealed a ligand-stabilized high-valent copper oxidant, with characteristic absorption at 358 nm and a signal at m/z 479 assigned to [Cu(III) - (NCP) 2 ] 3+ . This work provides a mechanistically grounded “reduction and complexation” strategy to overcome Cu - based persulfate activation bottlenecks and achieve rapid, pH - resilient degradation of NPX. • HA - NCP synergistically accelerates NPX degradation in Cu⁰/PMS system. • Cu(I) concentrations increased in the presence of reductants and complexants. • NCP increased the reduction rate of Cu(II) to Cu(I) by adding hydroxylamine. • [Cu(III) - (NCP) 2 ] 3+ identified as the dominant reactive species in the system.