Epigallocatechin-3-gallate-coated Fe3O4 as a novel heterogeneous catalyst of peroxymonosulfate for diuron degradation: Performance and mechanism

In this paper, epigallocatechin-3-gallate/Fe 3 O 4 , a novel heterogeneous catalyst to activate peroxymonosulfate for diuron degradation, was synthesized and its structure was well characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared, and X-ray photoelectron spectroscopy. It was found that the hybrid catalyst showed a better catalytic efficiency than both Fe 3 O 4 and epigallocatechin-3-gallate. This was resulted from the high reduction ability of epigallocatechin-3-gallate, which promoted the cycle of Fe(III)/Fe(II) on the surface of catalyst. Besides, batch experimental results showed that the degradation of diuron depended upon the dosage of catalyst and oxidant, initial pH, and co-existed humic acid. Results demonstrated that high catalyst and oxidant dosages, low initial pH and humic acid were favorable for diuron removal. Furthermore, by adding different dosages of methanol and tertiary butanol, two kinds of radicals were detected to be responsible for diuron degradation in this study and sulfate radical made the predominant contribution. At last, mineralization and degradation pathway were also evaluated in this study. Anyway, it was confirmed that the as-prepared catalyst has the potential superiority for contaminants removal from aqueous solution.