Efficient As(III) Removal by Novel MoS₂-Impregnated Fe-Oxide-Biochar Composites: Characterization and Mechanisms

Sorbents that efficiently eliminate toxic metal(loid)s from industrial wastes are required for the protection of the environment and human health. Therefore, we demonstrated efficient As(III) removal by novel, eco-friendly, hydrothermally prepared MoS₂-impregnated FeO @BC800 (MSF@BC800). The properties and adsorption mechanism of the material were investigated by X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller analysis, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The synergistic effects of FeO and MoS₂ on MSF@BC800 considerably enhanced As(III)-removal efficiency to ≥99.73% and facilitated superior As(III) affinity in aqueous solutions (K _d ≥ 10⁵ mL g^-1) compared to those of FeO @BC800 and MS@BC800, which showed 37.07 and 17.86% As(III)-removal efficiencies and K _d = 589 and 217 mL g^-1, respectively, for an initial As(III) concentration of ∼10 mg L^-1. The maximum Langmuir As(III) sorption capacity of MSF@BC800 was 28.4 mg g^-1. Oxidation of As(III) to As(V) occurred on the MSF@BC800 composite surfaces. Adsorption results agreed with those obtained from the Freundlich and pseudo-second-order models, suggesting multilayer coverage and chemisorption, respectively. Additionally, MSF@BC800 characteristics were examined under different reaction conditions, with temperature, pH, ionic strength, and humic acid concentration being varied. The results indicated that MSF@BC800 has considerable potential as an eco-friendly environmental remediation and As(III)-decontamination material.