Removal of arsenic(v) from aqueous solutions using sulfur-doped Fe3O4 nanoparticles

Abstract

In this study, magnetic sulfur-doped Fe₃O₄ nanoparticles (Fe₃O₄:S NPs) were applied as adsorbents for the removal of As(V). Fe₃O₄:S NPs were fabricated by a two-step route, which included low-temperature mixing and high-temperature sintering. The as-prepared Fe₃O₄:S NPs could effectively remove As(V) under a wide pH range of 2–10 and presented a high As(V) adsorption capacity of 58.38 mg g⁻¹, which was much better than undoped Fe₃O₄ nanoparticles (20.24 mg g⁻¹). Adsorption experiments exhibited a pseudo-second-order model of adsorption kinetics and a Langmuir isotherm model of adsorption isotherms. Additionally, the coexisting ions such as NO₃⁻, SO₄²⁻, and CO₃²⁻ had no significant effect on As(V) adsorption and the adsorbent worked well in actual smelting wastewater. XPS and FTIR spectra of Fe₃O₄:S NPs before and after As(V) adsorption showed that Fe–OH groups played a significant role in the adsorption mechanisms. Moreover, the magnetic Fe₃O₄:S NPs adsorbents after adsorption could be rapidly separated from wastewater with an external magnetic field. Therefore, Fe₃O₄:S NPs could be an ideal candidate for the removal of As(V) from water.