[Synergistic Reaction Mechanism of Cu⁰@Fe₃O₄ Activated PMS for Degradation of p-nitrophenol]

A Cu⁰/PMS system mainly relies on the leaching of copper ions to degrade the pollutants and adapt to the narrow pH range (<7). To solve this defect, we studied the properties and reaction mechanism of Cu⁰@Fe₃O₄ magnetic core-shell material, which was successfully prepared using co-precipitation method, taking PNP as the target pollutant. The results showed that: ① a degradation rate of 96% can be achieved within 60 min for 5 mg ·L^-1 PNP, 200 mg ·L^-1 Cu⁰@Fe₃O₄, and 0.5 mmol ·L^-1 PMS at a natural pH value (5.65); ② the Cu⁰@Fe₃O₄/PMS system can be regarded as a heterogeneous reaction system because TCu, TCu⁺, and iron leaching were almost negligible; ③ on comparing the performance of the Cu⁰@Fe₃O₄/PMS system and Cu⁰/PMS system in the pH range of 3 to 11, it was discovered that the method by which Cu⁰ activates the PMS to degrade the PNP was successfully changed by coating a layer of Fe₃O₄. The Cu⁰@Fe₃O₄/PMS system has a good degradation performance towards PNP in the pH range of 5-9; ④ SO^-₄ · and HO · existed in the reaction system, and their contribution rates to the reaction system were 34% and 60% ; HO · was the dominant free radical; ⑤ A bimetallic synergy exists between Fe and Cu. The presence of Cu(Ⅰ) can promote the reduction of Fe(Ⅲ) to Fe(Ⅱ), thereby forming a good redox cycle and improving the durability of the reaction system.