Study on the Adsorption-Deposition Behavior of Antimony on Typical Minerals in Soil

Human activities such as mineral mining and coal combustion cause a large amount of antimony to enter into the environmental soil. Exploring the adsorption deposition behavior of antimony on typical soil minerals is important for predicting the environmental fate of antimony and preventing its pollution. This article selected six kinds of commonly found metal hydroxides and clay minerals in soil (namely hematite, goethite, ferrihydrite, aluminum oxide, ramsdellite, and kaolinite) to systematically investigate the adsorption thermodynamic and kinetic behavior of Sb(Ⅲ) and Sb(Ⅴ) on their surfaces, and the adsorption mechanism were speculated. The order of adsorption capacities (mg/g) of six soil minerals for Sb(Ⅲ)/Sb(Ⅴ) were as follows: ferrihydrite (101.4, 55.9)＞ramsdellite (16.52, 7.58)＞goethite (13.3, 5.67)＞hematite (5.13, 3.7)＞aluminum oxide (1.66, 1.69)＞kaolinite (0.27, 0.51). Affected by the speciation of antimony and the surface potential of minerals, acidic conditions are favourable for the adsorption of Sb(Ⅴ), while the adsorption of Sb(Ⅲ) is less affected by pH. The Sb₂O₃ formed after deposition was in situ characterized by Raman spectroscopy. Sb(Ⅴ) adsorbs on the mineral by adsorption at different concentrations, while Sb(Ⅲ) may deposit on the mineral surface at higher concentrations.