Organically-coordinated Cu(II) mediated AOPs: A comparative study on different peroxides

The widespread presence of Cu(II) in aquatic environment has attracked increasing interests in Cu(II)-mediated advanced oxidation processes (AOPs) as a promising “two-birds-one-stone” strategies for environmental remediation. Organically coordinated Cu(II) systems offer dual benefits on facilitating efficient copper redox cycling and generating reactive species for pollutant degradation. However, the activation efficiency disparities among different peroxides and their underlying mechanisms remain poorly understood. Herein, this study presents a comprehensive comparison of organically-cooridinated Cu(II) activated peroxydisulfate (PDS), peroxymonosulfate (PMS) and hydrogen peroxide (H 2 O 2 ) systems, where ofloxacin (OFX) serving as coordinating ligand and target contaminant. Our results demonstrate enhanced activation for all the three peroxides, leading to significantly improved OFX degradation. High-valent copper species Cu(III) is identified as the primary working intermediate across all systems. The peroxides activation efficiency, OFX decay enhancement, and steady-state Cu(III) concentration consistently followed an order of PDS > H 2 O 2  > PMS. The performance differences among the three systems were governed by the initial contact probability between peroxides and copper center and the subsequent electron transfer efficiency, which is further verified by molecular dynamics (MD) simulations. This work establishes a quantitative framework for predicting peroxides activation properties in Cu(II)-mediated AOPs, offering fundamental insights for designing efficient dual-functional systems that combine heavy metal stabilization with organic pollutant degradation in wastewater treatment.