Fabrication and characterization of KGM-based FMBO-containing aerogels for removal of arsenite in aqueous solution

Abstract

Hybrid materials were obtained by immobilizing Fe and Mn oxides (FMBO) into a konjac glucomannan (KGM) based aerogel matrix to remove arsenite from water. Composite adsorbents were prepared through a coupling sol–gel process with a suitable freeze-drying technique. The KGM aerogels were employed as the framework and FMBO as the coating materials. Scanning electron microscopy (SEM), thermo gravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used for the characterization of the hybrid aerogels. The adsorption of As(III) by the composite aerogels decreased with increasing pH. Isotherms were well predicted by Freundlich behavior, implying the heterogeneous nature of the As(III) adsorption. The maximum As(III) uptake capacity reached 30.33 mg g⁻¹ at the FMBO/KGM ratio of 1.5 : 1 at pH 7 and 323 K. The effects of coexisting anions including Cl⁻, NO³⁻, SO₄²⁻, SiO₃²⁻, PO₄³⁻ as well as natural organic matter, which possibly exist in natural water, on As(III) removal were also investigated. The hybrid adsorbents could be easily regenerated by using NaOH solution, exhibiting excellent practicability and reusability. Furthermore, XPS analysis of composite aerogels before and after the reaction confirmed the oxidation–sorption mechanism for As(III) removal. This research extends the potential applicability of KGM-based aerogels and provides an eco-friendly and convenient approach to efficiently remove trace As(III) from aqueous solutions.