Carbon nitride supported copper catalyst activating peroxydisulfate for efficient paracetamol degradation.

The heterogeneous Fenton-like reaction with peroxydisulfate (PDS) is a highly promising technology for the degradation of pharmaceuticals and personal care products (PPCPs). It does not require a light or heat source, has a broader pH applicability, and does not cause secondary pollution or catalyst loss. In this study, we synthesized a highly dispersed Cu-doped graphitic carbon nitride catalyst (Cu/C3N4). Catalyst characterization results confirmed that the main pore size ranged from 0 to 4 nm, and Cu(I) and Cu(II) were highly uniformly dispersed onto the graphitic carbon nitride matrix. The Cu/C3N4 catalyst exhibited superior performance in activating PDS for paracetamol degradation under neutral pH conditions, achieving a catalytic efficiency of 7.82 L/(min·g-Cu). No obvious decrease in the paracetamol removal rate was observed over the eight successive cycles, indicating extraordinary reusability of the Cu/C3N4 catalyst. The removal efficiency of paracetamol in secondary effluent and river water was inhibited due to the influence of inorganic ions and organic matter, but approximately 80 % paracetamol removal was still achieved in actual waters within 30 min. Radical quenching and electron spin-resonance spectroscopy results indicated that radical pathways (mainly SO4•-) and nonradical pathways (singlet oxygen and mediated electron transfer) were the main degradation mechanisms. The transformational products identified by HPLC-QTOF-MS were mainly p-nitrophenol, hydroquinone, p-benzoquinone, butanediol, and glycerol. This study provides insights into the performance and mechanisms of Cu/C3N4/PDS oxidation for paracetamol degradation, highlighting its potential for PPCPs removal and sustainable water reclamation.