凹凸棒石-双交联水凝胶微球钝化修复镉污染土壤研究

为研究凹凸棒石-双交联水凝胶微球(SA/PVA/ATP)对镉污染土壤钝化修复的效果，将SA/PVA/ATP添加到镉浓度为3.72 mg/kg的土壤中进行淹水培育，采用模拟酸雨、二乙烯三胺五乙酸(DTPA)和三乙醇胺(TEA)混合提取剂(DTPA提取剂)提取土壤有效态镉；采用欧共体标准局顺序提取方法(BCR)提取土壤中不同形态镉；讨论了SA/PVA/ATP添加量、土壤有效态镉和各形态镉的相关性；计算了钝化容量、修复效率和重金属风险评价指数，探究了SA/PVA/ATP对土壤镉的钝化机理。结果显示，随着SA/PVA/ATP的增加，DTPA提取剂和酸雨提取的有效态镉含量分别从1.72 mg/kg和0.024 mg/kg下降到0.66 mg/kg和0.004 4 mg/kg;土壤中的弱酸可提取态镉和可还原态镉含量分别从1.40 mg/kg和0.81 mg/kg下降到1.01 mg/kg和0.41 mg/kg,而可氧化态镉和残渣态镉含量分别从0.86 mg/kg和0.63 mg/kg增加到0.95 mg/kg和1.27 mg/kg。材料添加量与土壤中有效态镉、弱酸提取态镉和可还原态镉含量呈极显著负...

Passivation remediation of cadmium contaminated soil by attapulgite-double-crosslinked hydrogel microspheres

In order to study the passivation remediation effect of attapulgite-double-crosslinked hydrogel microspheres (SA/PVA/ATP) on cadmium contaminated soil, SA/PVA/ATP was added to cadmium contaminated soil with concentration of 3.72 mg/kg for flooding cultivation, using simulated acid rain, mixed extractant of diethylenetriamine pentaacetic acid (DTPA) and triethanolamine (TEA) (DTPA extractant) to extract available cadmium, and using sequential extraction method of the European Community Bureau of Standards (BCR) to extract different forms of cadmium in soil. The correlation between SA/PVA/ATP addition, available cadmium and various forms of cadmium in soil was discussed. The passivation capacity, remediation efficiency and heavy metal risk assessment index were calculated, and the passivation mechanism of SA/PVA/ATP on soil cadmium was explored. The results show that with the increase of the amount of SA/PVA/ATP, the available cadmium content of DTPA extractant and acid rain extraction decrease significantly from 1.72 mg/kg and 0.024 mg/kg to 0.66 mg/kg and 0.004 4 mg/kg respectively, the content of weak acid extractable and reducible cadmium in soil decrease significantly from 1.40 mg/kg and 0.81 mg/kg to 1.01 mg/kg and 0.41 mg/kg, respectively, while the content of oxidizable and residual cadmium increase significantly from 0.86 mg/kg and 0.63 mg/kg to 0.95 mg/kg and 1.27 mg/kg, respectively. The addition of material has a significant negative correlation with available cadmium, weakly acid extractable cadmium and reducible cadmium, while a significant positive correlation with oxidizable cadmium and residual cadmium. When the addition of SA/PVA/ATP is 2.0%, the maximum passivation capacity is 19.15 mg/kg, the maximum remediation efficiency is 34.89%, and the soil environment fall from high risk to medium risk. SA/PVA/ATP can reduce the bioavailability of cadmium and realize the passivation remediation of cadmium contaminated soil through transforming the weak acid extracted and reducible forms into oxidizable and residual forms in soil.