Preparation and characterization of Fe3O4/gallic acid/graphene oxide magnetic nanocomposites as highly efficient Fenton catalysts

Abstract

In this study, Fe₃O₄/gallic acid/graphene oxide magnetic nanocomposites (Fe₃O₄/GA/GO MNPs) were synthesized as heterogeneous Fenton catalysts to activate H₂O₂ to degrade methylene blue (MB). The catalysts were characterized by X-ray diffraction (XRD), zeta potential analysis, thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The addition of GA resulted in crystal defects on the surface of Fe₃O₄/GA/GO which improved its catalytic properties. Moreover, Fe₃O₄/GA/GO had larger surface area, correspondingly exposing more active sites for H₂O₂ activation, as well as enhancing the adsorption of MB which also promoted its catalytic properties. Complete removal of MB (0.2 mM) and remarkable mineralization of total organic carbon (TOC) (66.7%) were obtained within 420 min at pH 6.0 and 30 °C by using 1.0 g L⁻¹ Fe₃O₄/GA/GO MNPs and 160.0 mM H₂O₂. Furthermore, MB could be completely degraded by Fe₃O₄/GA/GO MNPs in a wide pH value ranging from 3.0 to 10.0. The catalyst showed stable catalytic activity, as well as good mechanical stability, and could be recycled 10 times.