改性硅酸钙对Cd2+的吸附性能及其对Cd污染土壤的修复潜力

通过吸附-解吸实验和土柱淋溶实验，研究了改性硅酸钙对镉(Cd2+)的吸附性能及对Cd污染土壤的钝化效果。结果表明，改性硅酸钙对Cd2+有较强的吸附能力，其吸附平衡时间在60 min左右，对溶液pH有较宽的适应范围，且当pH呈中性时，对Cd2+的吸附效果最好。由Langmuir模型拟合结果可知，改性硅酸钙对Cd2+的饱和吸附容量可达441.55 mg·g-1。改性硅酸钙对Cd2+有较好的吸附稳定性，适合用于Cd污染土壤的修复。土柱淋溶实验表明，改性硅酸钙对Cd污染土壤的钝化效果明显，不仅降低淋溶液Cd2+含量，使淋溶液Cd2+累积量显著降低47.01%，还使土壤CaCl2-Cd浓度显著降低94.4%，并促使土壤易溶态Cd向难溶态Cd转变。

Cd2+ adsorption performance of modified calcium silicate and its potential on Cd contaminated soil remediation

The Cd2+ adsorption performance of modified calcium silicate and its passivation effect on Cd contaminated soil were studied by adsorption-desorption experiment and soil column leaching experiment. The results showed that the modified calcium silicate had a strong performance on Cd2+ adsorption, and its adsorption equilibrium time was about 60 min. It had a wide adaptability to the solution pH, and the maximum Cd2+ adsorption capacity occurred at neutral pH. The saturated adsorption capacity of modified calcium silicate to Cd2+ could reach 441.55 mg·g-1 based on the fitting results with Langmuir model. In addition, the modified calcium silicate presented a good adsorption stability to Cd2+, and was suitable for Cd contaminated soil remediation. Soil column leaching experiments showed that the modified calcium silicate had a significant effect on Cd contaminated soil passivation, which not only reduced the Cd2+ concentration of the leaching solution, but also significantly reduced the Cd2+ accumulation in the leaching solution by 47.01%, and the CaCl2-Cd concentration in soil by 94.4%, and promoted the transformation of soluble Cd species to insoluble Cd species in soil. It was shown that modified calcium silicate can be used for Cd contaminated soil remediation.