Cu(II)-catalyzed thermally activated persulfate for carbamazepine degradation: Efficiency and mechanistic insights

The thermally activated persulfate (PDS/thermal) system has been widely explored for removing refractory organic pollutants, yet its efficiency remains constrained by energy demand and limited radical generation. In this study, Cu(II) was introduced as a homogeneous catalyst to enhance carbamazepine (CBZ) degradation in the PDS/thermal process. Under optimal conditions (40 μM Cu(II), 1 mM PDS, 60 °C), complete CBZ removal was achieved within 20 min, with the pseudo-first-order rate increased by 62 % compared to the PDS/thermal system without Cu(II). Probe experiments and density functional theory (DFT) calculations verified that SO 4 •− , • OH, and high-valent Cu(III) jointly contributed CBZ degradation, with SO 4 •− remaining the predominant reactive species. Arrhenius analysis revealed a reduction in apparent activation energy by 22.11 kJ·mol −1 , further supporting the the catalytic role of Cu(II) in facilitating O O bond cleavage and radical production. UPLC-QTOF-MS/MS identified hydroxylation, epoxidation, and deacetylation as major transformation pathways, yielding products with generally lower or comparable toxicity relative than CBZ. Moreover, the Cu(II)-PDS/thermal system demonstrated strong adaptability to pH variations, background ions, natural organic matter, and diverse organic pollutants, and maintained high efficiency in real water samples. These findings highlight the synergistic role of Cu(II) in thermal persulfate activation and provide mechanistic and practical insights for its application in the remediation of pharmaceutical-contaminated waters.