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The yolk-shell Co3O4@Fe3O4/C nanocomposites with Co3O4 as the core, Fe3O4/C as the shell, and a cavity structure were synthesized by the hard template method. The physical and chemical properties of the composites were characterized by SEM, TEM, XRD, TGA, XPS, BET, and VSM. The specific surface area of yolk-shell Co3O4@Fe3O4/C nanocomposites is 175.9 m2 g-1, showing superparamagnetic properties. The yolk-shell Co3O4@Fe3O4/C nanocomposites were used as heterogeneous Fenton catalysts to activate peroxymonosulfate (PMS) to degrade MB, which showed high catalytic degradation performance. The degradation rate of MB reached 100% within 30 min under the circumstances of the yolk-shell Co3O4@Fe3O4/C nanocomposites dosage of 0.1 g L-1, the PMS dosage of 1.0 g L-1, the initial MB concentration of 100 mg L-1, an initial pH of 5.5, and a temperature of 30±2 ℃. The enhanced catalytic performance of the yolk-shell Co3O4@Fe3O4/C nanocomposites can be attributed to the synergistic effect of the two catalytically active materials and the middle cavity. The effects of different operating parameters and co-existing anion species on MB degradation were also investigated. Electron paramagnetic resonance (EPR) analysis and quenching experiments confirmed that the formation of SO₄̇⁻ in the yolk-shell Co3O4@Fe3O4/C/PMS system contributes to MB degradation. In addition, yolk-shell Co3O4@Fe3O4/C nanocomposites can be easily separated from the pollutant solution under the action of an external magnetic field, and the degradation rate of MB can still reach 98% after five cycles, indicating that it has good stability and reusability and has broad application prospects in the field of water purification.

The unintended leakage of endocrine-disrupting bisphenol A (BPA) from different industries into the aquatic environment has posed a severe threat to aquatic lives and human health. Herein, we explored a hydrothermal method to synthesize superparamagnetic β-cyclodextrin-cobalt ferrite (β-CD-CoFe2O4) catalyst for the selective capturing and efficient degradation of BPA through heterogeneous activation of peroxymonosulfate (PMS). The as-prepared catalysts were systematically characterized through multi-techniques to explore the relationship between their catalytic performance and material properties. Results showed that, in β-CD-CoFe2O4/PMS system, the degradation rate of BPA reached 99.23% in 60 min with a rate constant of 0.0708 min−1, approximately 16.09 times than CoFe2O4/PMS system (0.0044 min−1). Specifically, the large surface area and availability of more reactive sites of β-CD-CoFe2O4 boosted the activation process of PMS compared to pristine CoFe2O4, thus enhancing the degradation of BPA. Meanwhile, the effect of different operational parameters and co-existing anions on BPA degradation were also investigated. The generation of free radicals ( S O 4 ∙ - , ∙ O H , O 2 ∙ - , a n d 1 O 2 ) in the β-CD-CoFe2O4/PMS system liable for reducing BPA was corroborated through electron paramagnetic resonance analysis and quenching experiments. The possible degradation pathways of BPA were proposed based on the identification of reaction intermediates formed during the mineralization process. In brief, the findings of this study suggested that β-CD-CoFe2O4 is an efficient and environmentally friendly catalyst that facilitated the degradation of BPA through PMS activation. Moreover, the excellent magnetic separation, stability, and reusability of the β-CD-CoFe2O4 catalyst make them promising candidates for their water purification applications.