Heterogeneous catalytic degradation of organic pollutants by peroxymonosulfate activated with nitrogen doped graphene oxide loaded CuFe2O4

Abstract

Nitrogen doped graphene oxide loaded CuFe2O4 nanoparticles (CuFe2O4-NG) catalyst was successfully synthesized by thermal annealing and hydrothermal reaction approaches for degrading organic pollutants by peroxymonosulfate (PMS) activation. CuFe2O4-NG exhibited superior degradation efficiency toward orange II among GO, NG, CuFe2O4 and CuFe2O4-NG. The obtained catalysts were systemically characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Raman spectrum analysis and X-ray photoelectron spectroscopy to understand the relationship between inner structure and catalytic activity. It can recognize the key reactive oxygen species including SO4•–, •OH, O2•– and 1O2 in CuFe2O4-NG/PMS degradation system by electron paramagnetic resonance and free radical quenching studies, indicating the existence of both radical pathway and non-radical pathway. Based on the valence state changes of Cu and Fe in XPS spectra, the redox cycles between Fe(III) and Fe(II), Cu(II) and Cu(I) mediated by HSO5– contributed to the production of SO4•–, •OH and O2•–. Carbonyl groups and ketonic groups on the catalyst could promote the self-decomposition of PMS, leading to the generation of 1O2. The synergistic effect between NG and CuFe2O4 can accelerate the activation of PMS and pose the new insight for organic pollutants removal.