Zero valent iron as an electron transfer agent in a reaction system based on zero valent iron/magnetite nanocomposites for adsorption and oxidation of Sb(III)

Abstract

Abstract Due to the toxicity and carcinogenicity, antimony and its compounds have been included as priority pollutants by Environmental Protection Agency of the United States (USEPA) and the European Union (EU). The removal methods of antimony need to be further studied. In this study, nZVI/Fe3O4 nanocomposites were synthesized, characterized, and applied to remove Sb(III). The nZVI/Fe3O4 nanocomposites before and after reaction with Sb(III) were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), vibrating sample magnetometry (VSM), and X-ray photoelectron spectroscopy (XPS). nZVI/Fe3O4 nanocomposites have a maximum Sb(III) adsorption capacity of 87.6 mg/g at pH 7.0. The removal of Sb(III) was a complex process including surface adsorption and oxidation. The removal of Sb(III) mainly involved three processes: (1) most Sb(III) was adsorbed on the surface of nZVI/Fe3O4 nanocomposites; (2) part of Sb(III) was rapidly oxidized to less toxic Sb(V); and (3) the generated Sb(V) was further adsorbed on the surface of nZVI/Fe3O4 nanocomposites. The nZVI/Fe3O4 nanocomposites can be separated from solution with an external magnet. The high Sb(III) removal efficiency and rapid separability of nZVI/Fe3O4 nanocomposites exhibited the great potential for the removal of Sb(III) from wastewater.