Construction of core–shell magnetic metal–organic framework composites Fe3O4@MIL-101(Fe, Co) for degradation of RhB by efficiently activating PMS

Low catalytic efficiency and catalyst recovery are the key factors limiting the practical application of advanced oxidation processes. In this work, a core-shell magnetic nanostructure Fe₃O₄@MIL-101(Fe, Co) was prepared via a simple solvothermal method. The core-shell structure and magnetic recovery performance were characterized by various technologies. The results of dye degradation experiments proved that within 10 minutes, the Fe₃O₄@MIL-101(Fe, Co)/PMS system can degrade more than 95% of 10 mg per L Rhodamine (RhB) at an initial pH of 7, which possesses higher catalytic activity than the Fe₃O₄/PMS system and the MIL-101(Fe, Co)/PMS system. The effects of initial solution pH and coexisting anions in water on the degradation of RhB were further discussed. The results showed that Fe₃O₄@MIL-101(Fe, Co) displayed excellent degradation efficiency in a wide pH range of 3-11 and capability of resisting coexisting anions. It is worth mentioning that after five cycles, the RhB removal rate can still be maintained at over 90% after 10 minutes of reaction. Free radical quenching experiments were further studied, confirming that ˙OH and SO₄^-˙ were involved in the degradation of RhB, while the dominating active free radical was SO₄^-˙. The possible reaction mechanism of the RhB degradation process was also inferred.