Fe/Zr/AlOx-modified graphene oxide-chitosan aerogels for efficient removal of As(III) and Sb(III) from mining groundwater: Adsorption selectivity and mechanistic insights

Abstract

Arsenic (As) and antimony (Sb) contamination in groundwater poses serious threats to the environment and human health. In this study, graphene oxide–chitosan aerogel microspheres loaded with Fe/Zr/Al ternary oxides (IZA@GCAMs) were synthesized and systematically evaluated for their adsorption performance. IZA@GCAMs exhibited a high specific surface area (150–165 m²/g) and a hierarchical pore structure. Thermogravimetric analysis revealed that the incorporation of metal oxides enhanced structural stability and delayed thermal decomposition. Meanwhile, the amino and hydroxyl groups of chitosan not only provided initial binding sites for As(III) but also promoted the uniform dispersion of metal oxides and participated in subsequent complexation. The maximum adsorption capacities reached 248.51 mg/g for As(III) and 314.39 mg/g for Sb(III). Mechanistic studies indicated that As(III) first interacts with the functional groups of the chitosan matrix before binding to oxide sites, whereas Sb(III) directly forms stable complexes with Fe/Zr/AlOx, accompanied by partial oxidation, and in binary systems significantly suppresses As(III) removal by preferential site occupation. Density functional theory (DFT) calculations show that Sb(III) preferentially binds to FeO_x, followed by ZrO_x and AlO_x, while As(III) tends to bind first to ZrO_x, then to FeO_x and AlO_x. The material showed robust performance over pH 3–10 and high reusability, and efficiently reduced As/Sb in real groundwater. These findings elucidate the competitive adsorption mechanisms of As(III) and Sb(III) and demonstrate the practical application potential of this material in remediating As and Sb-contaminated groundwater.