Synergistic degradation of methylparaben on CuFe2O4-rGO composite by persulfate activation

Abstract

Methylparaben (MeP), as emerging contaminants widely used in pharmaceuticals and personal care products, have potential endocrine disrupting effect. In this study, the copper ferrite (CuFe2O4) nanoparticles were uniformly distributed on graphene oxide (GO), and the performance and mechanism of CuFe2O4-rGO composites in activating persulfate (PS) for MeP degradation were comprehensively investigated. Results showed that the CuFe2O4-rGO composites exhibited much better efficiency for MeP degradation than CuFe2O4, and the synergistic effect between CuFe2O4 and GO in CuFe2O4-rGO composite was also observed. The best catalytic performance of CuFe2O4-rGO composites was obtained at the mass ratio of 4:1 for CuFe2O4 to GO and at neutral pH. X-ray photoelectron spectroscopy (XPS) results suggested that graphene in the composites mainly served as an electron shuttle to mediate electron transfer reactions. Electron paramagnetic resonance (EPR) and the quenching experiments further revealed that both hydroxyl and sulfate radicals were the major reactive species, and non-radical process also occurred during the reaction. Meanwhile, the degradation pathways of MeP involving hydroxylation, decarbonylation and ring opening were rationally proposed based on computational method and intermediates identification. All these results could provide insight into persulfate activation by CuFe2O4-rGO nanocomposites in environmental control applications.