铝酸盐材料对镉污染土壤的稳定化修复及其机理

为研究铝酸盐材料对于修复Cd污染土壤的可行性，以常见的硅酸盐材料为参照，比较了两者对土壤中Cd的稳定化效果，并对相关反应机制进行了讨论。结果表明：当土壤中Cd的质量分数为54.6 mg·kg⁻¹时，铝酸盐和硅酸盐材料使Cd的7 d浸出质量浓度分别降低58.07%~77.75%和63.46%~93.02%，180 d浸出质量浓度分别降低28.72%~79.23%和41.08%~86.63%；当土壤中Cd的质量分数为2 940.03 mg·kg⁻¹时，铝酸盐和硅酸盐材料使Cd的7 d浸出质量浓度分别降低76.97%~93.15%和19.05%~94.38%，180 d浸出质量浓度分别降低56.56%~88.87%和-32.68%~49.79%。这说明铝酸盐材料对土壤中Cd的稳定化效果优于硅酸盐材料。在CdCl₂溶液中(94.02 mg·L⁻¹)，铝酸盐和硅酸盐材料分别使Cd质量浓度降低了99.92%~99.93%和99.68%~99.92%，并使pH分别增大了6.56~6.81和7.01~7.69。通过SEM-EDS、FTIR、XRD和XPS等分析手段发现，铝酸盐材料可通过水化反应生成Ca—Si—H和Ca—Al—Si—H凝胶，以实现对Cd的物理包裹和吸附，并可通过使pH增大而生成Cd(OH)₂、CdO或CdCO₃沉淀，进而实现了对Cd的稳定化。本研究表明铝酸盐材料较硅酸盐材料对Cd的稳定化更为高效且长效，可为Cd污染土壤修复提供参考。

Stabilization and remediation of Cadmium contaminated soil by Aluminate and its mechanisms

In order to explore the feasibility of aluminate in cadmium contaminated soil remediation, the stabilization effects of aluminate material on cadmium polluted soil were compared with traditional silicate material, and the related reacion mechanism was expounded. The results showed that when the mass fraction of Cd was 54.6 mg·kg−1, the leaching mass concentration of Cd at 7 d decreased by 58.07%~77.75% and 63.46%~93.02% with aluminate and silicate materails, respectively, and the leaching mass concentration at 180 decreased by 28.72%~79.23% and 41.08%~86.63%, respectively.. When the mass fraction of Cd was 2 940.03 mg·kg−1, the leaching mass concentration of Cd at 7 d decreased by 76.97%~93.15% and 19.05%~94.38% with aluminate and silicate materails, respectively, and the leaching mass concentration of Cd at 180d decreased by 56.56%~88.87% and −32.68%~49.79%, respectively. These results indicated that aluminate material was more efficient in stabilization of cadmium in soil than silicate material. In CdCl2 solution (94.02 mg·L−1), aluminate and silicate reduced Cd concentration by 99.92%~99.93% and 99.68%~99.92%, respectively, and increased pH by 6.56~6.81 and 7.01~7.69, respectively. Through SEM-EDS, FTIR, XRD and XPS analysis, it was found that aluminate could form Ca—Si—H and Ca—Al—Si—H gels through hydration reaction to achieve physical encapsulating and adsorption of Cd. In addition, aluminate could also increase pH to generate Cd(OH)2, CdO or CdCO3 to realize the stabization of Cd. In conclusion, aluminate was more efficient and long-term in stabilization of cadmium than silicate, which can provide reference for the remediation of cadmium-contaminated soil.