Preparation of Oil Sludge-Based Activated Carbon Loaded with CuO/Fe2O3 and Its Mechanism in Activating Peroxymonosulfate for p-Nitrophenol Degradation

In this study, oil sludge was utilized as a carbon source to prepare a carbon-based catalyst. By leveraging the oil sludge’s inherent iron content and subsequently introducing exogenous copper, a CuO/Fe2O3/carbon composite material (OSC-0.75Cu) was synthesized for the activation of peroxymonosulfate (PMS) to degrade p-nitrophenol. The OSC-0.75Cu/PMS system achieved a degradation efficiency of 92.19%, which was 2.91 times that of the OSC/PMS system (31.71%), and its reaction rate constant (kobs) was 8.9 times greater. Furthermore, in simulated water matrices (containing anions and fulvic acid) and three real water matrices (rainwater, moat water, and Yangtze River water), the OSC-0.75Cu/PMS systemachieved PNP degradation efficiencies ranging from 71.63% to 76.36%. The degradation of p-nitrophenol in this system involves three primary reactive species: hydroxyl radicals (•OH), sulfate radicals (•SO4−), and singlet oxygen (1O2), among which 1O2 plays the dominant role. The coexistence of Cu and Fe species may facilitate surface redox reactions during PMS activation, while defect-related oxygen sites may contribute to PMS adsorption and activation and the generation of 1O2. This study provides a novel strategy that enables the resource utilization of oil sludge while simultaneously addressing environmental remediation challenges.