S-doped α-Fe2O3 as a highly active heterogeneous Fenton-like catalyst towards the degradation of acid orange 7 and phenol

Abstract

S-doped α-Fe2O3 (α-Fe2O3/S) was synthesized with ferrous sulfate and Na2S2O3 via a hybrid hydrothermal-calcination treatment. The crystal phase, special surface area, morphology of the α-Fe2O3/S as well as the chemical state of the sulfur were studied by X-ray diffraction (XRD), scanning electro microscopy (SEM), Raman spectrum and X-ray photoelectron spectroscopy (XPS). The Fenton and photo-Fenton reactivities of the α-Fe2O3/S were tested by degrading acid orange 7 (AO7) and phenol. Although α-Fe2O3/S showed little Fenton reactivity in the dark, it had an excellent heterogeneous Fenton reaction under either UV or visible irradiation, while other α-Fe2O3s were still kept inactive. S element was found to dope into α-Fe2O3 in the forms of FeS or FeS2 in α-Fe2O3/S. The doped S element promotes the photo-Fenton reaction of α-Fe2O3/S via two roles: retarding the recombination of photogenerated charge carriers and promoting the electron transfer between the peroxide species and iron ions at the interface.