Preparation of Silicon/Iron Binary Aerogel from High Iron Fly Ash and Adsorption of Mine Antimony Wastewater

In this paper, silicon/iron binary aerogel (shortened to HFGel in the following text) was prepared from industrial solid waste fly ash. Antimony in the simulated solution and mine antimony wastewater were adsorbed with HFGel, respectively. The results showed that (1) HFGel has a three-dimensional network structure consisting of spherical nanoparticles with a specific surface area of about 346.4 m²/g, a pore size of 4.42 nm, and a pore volume of 0.43 cm³/g. (2) The adsorption of Sb(V) relies on the functional Fe-OH. The maximum adsorption capacity of HFGel on Sb(V) was 58.82 mg/g. The adsorption of Sb(V) by HFGel followed the secondary adsorption kinetics and Langmuir adsorption isotherm model. (3) The adsorption efficiency of HFGel decreased from 93% to 80.4% after five cycles. (4) HFGel has excellent selective adsorption performance for antimony. When the concentrations of CO₃²⁻, SO₄²⁻ and PO₄³⁻ were 300 mg/L, 500 mg/L, and 100 mg/L, respectively, the removal rates of Sb(V) were 91.9%, 89.9%, and 83.7%, respectively. (5) After a single oxidation-adsorption process, HFGel removed 99.2% of antimony from mine wastewater. The concentration of effluent is < 8 μg/L.