新型杂化材料钝化修复镉铅复合污染土壤的效应与机制研究

Effect and Mechanism of Immobilization of Cadmium and Lead Compound Contiminated Soil Using New Hybrid Material

采用盆栽实验,研究了新型杂化材料及其与磷酸盐复配使用对镉铅复合污染土壤的钝化修复效果,并通过重金属形态分析、吸附平衡实验以及X射线光电子能谱(XPS)探讨了杂化材料钝化修复重金属污染土壤的机制.结果表明,杂化材料单一处理对油菜生长没有明显的促进作用,而杂化材料与磷酸盐复合处理则能显著提高油菜地上部和根部生物量,分别比对照最大增加75.53%和151.22%.不同杂化材料处理均可显著降低油菜体内Cd、Pb含量,可使油菜地上部Cd、Pb含量分别最大降低66.79%和48.62%;杂化材料与磷酸盐复配处理抑制油菜吸收Cd、Pb的效果优于杂化材料单一处理.不同杂化材料处理均可显著降低土壤TCLP提取态Cd、Pb含量,其中杂化材料与磷酸盐复配处理降低TCLP提取态Cd、Pb含量的效果显著优于杂化材料单一处理.杂化材料通过其表面的巯基与Cd、Pb离子发生配位反应,形成双齿配体来吸附固定土壤中的Cd、Pb活性组分,促进土壤中的Cd、Pb由活性高的酸可提取态向活性低的残渣态转化,从而显著降低Cd、Pb在土壤中的生物有效性和可迁移性,进而达到钝化修复Cd、Pb复合污染土壤的目的.综合实验结果,杂化材料与磷酸盐复配使用对镉铅复合污染土壤的钝化修复效果最佳,杂化材料主要通过专性化学吸附反应来钝化修复土壤镉铅污染.

The effect of new hybrid material and its compound treatments with phosphate on immobilization of cadmium and lead in contaminated soil was investigated using a pot-culture experiment,and the immobilization mechanism of hybrid material was clarified through analysis of heavy metal fractions,sorption equilibration experiment and X-ray photoelectron spectroscopy（XPS）.The single treatments of hybrid material could not significantly promote growth of Brassica chinensis,while the compound treatments of hybrid material and phosphate markedly increased dry biomass of shoots and roots,with maximal increases of 75.53% and 151.22%,respectively.Different hybrid material treatments could significantly reduce Cd and Pb concentrations in shoots,with maximal reductions of 66.79% and 48.62%,respectively,and the compound amendment treatments appeared more efficient than the single amendment treatments in reducing Cd and Pb uptake of B.chinensis.Different hybrid material treatments could significantly decrease concentrations of toxicity characteristic leaching procedure（TCLP） extractable Cd and Pb,and the compound hybrid material treatments appeared more efficient than the single treatments in reducing TCLP extractable Cd and Pb.Through the formation of bidentate ligand between metal ions and surface sulfhydryl by complexing reaction,the hybrid material could absorb and fix mobile fractions of Cd and Pb in soil,and promote transformation of acid extractable Cd and Pb into residual fraction,resulting in significant reduction of heavy metals bioavailability and mobility and then fixing remediation of contaminated soil.In summary,the compound treatment of hybrid material and phosphate is the most effective treatment for immobilization of Cd and Pb in contaminated soils,and the hybrid material inactivates Cd and Pb in soil mainly through special chemical adsorption.