[Preparation of Iron-based Lime-reinforced Passivation Material and Its Passivation Effect on Sb]

As a solidified material, iron salt has a good effect on the remediation of soil antimony （Sb） pollution, but its improper use will cause soil acidification and reduce the remediation effect. The ferric sulfate cornerstone ash-reinforced passivation material （FS） and the polyferric sulfate cornerstone ash-reinforced passivation material （PFS） were prepared by using ferric sulfate, polyferric sulfate, and quicklime as raw materials. The morphology and characteristics of the materials were analyzed using X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and Fourier transform infrared spectroscopy （FTIR）. The adsorption mechanism and remediation effect of the two materials on soil Sb were studied by an adsorption experiment and a soil culture experiment. The results showed that FS and PFS were mainly composed of iron and calcium oxides and hydroxides, which contained hydroxyl, carbonyl, and other functional groups. The Freundlich model fitted the isothermal adsorption data well, indicating that the adsorption of Sb （Ⅲ） by both materials was multilayer adsorption. The adsorption capacity of Sb （Ⅲ） by FS and PFS increased with the increase in materials added. The pseudo-second-order kinetic model fitted the adsorption kinetics of FS and PFS well. Among the coexisting ions, PO₄^3- had the greatest effect on the adsorption of Sb （Ⅲ） by FS and PFS, and the presence of a high concentration of （0.1 mol·L^-1） PO₄^3- significantly inhibited the adsorption of Sb （Ⅲ） by FS and PFS. In the presence of low concentrations （0.01 mol·L^-1 and 0.001 mol·L^-1） of PO₄^3-, the adsorption of Sb （Ⅲ） by FS and PFS was promoted. The addition of FS and PFS could reduce the total Sb （T） and trivalent Sb （Ⅲ） contents of extractable citric acid in the soil. The soil culture experiment showed that adding 5% FS and PFS could reduce the exchangeable Sb content in heavily polluted soil by 66.39% and 72.88%, respectively, and reduce the exchangeable Sb content in mildly polluted soil by 56.04% and 56.86%, respectively. Soil pH and electrical conductivity （EC） increased significantly with the increase in material addition. In conclusion, FS and PFS had efficient adsorption properties for both aqueous solution and soil Sb, and application in acidic soil could significantly improve soil pH, indicating that both materials could effectively passivate soil Sb and alleviate soil acidification and have great potential in passivating remediation of Sb-polluted soil.