聚合氯化铝铁/凹凸棒石对土壤Cd环境风险影响

Influence of PAFC Modified Attapulgite on Soil Cd Environmental Risk

采用浸渍法将聚合氯化铝铁(PAFC)与凹凸棒石混合,制备一系列聚合氯化铝铁改性凹凸棒石钝化材料,采用扫描电镜、X射线衍射仪和傅里叶红外光谱仪对其进行表征,通过钝化试验和欧洲共同体参考机构(BCR)多级提取法评价聚合氯化铝铁改性凹凸棒石对土壤中重金属Cd的钝化效果和环境风险。结果表明,添加聚合氯化铝铁改性凹凸棒石使土壤pH值显著上升,土壤中重金属Cd由活性较高的酸溶态向活性较低的可还原态、可氧化态和残渣态转变,聚合氯化铝铁质量分数为25%的改性凹凸棒石钝化效果最佳,土壤酸溶态Cd含量较原土降低29.27%,土壤残渣态Cd含量升高24.32%,环境风险因子最低,为24.15%。

A series of attapulgite modified by poly-aluminum ferric chloride(PAFC)stabilization materials were prepared by mixing polyaluminum ferric chloride with attapulgite by the impregnation method and characterized by SEM,XRD and FTIR.The stabilization effect and environmental risk of poly-aluminum ferric chloride modified attapulgite on Cd in soils were evaluated by stabilization experiment and BCR extraction method.When modified attapulgite was applied into the soil,the pH value significantly increased compared with the control group.The application of attapulgite modified by poly-aluminum ferric chloride promoted the transformation of Cd in contaminated soil from acid-soluble speciation to reducible,oxidizable and residual speciation.The treatment effect of modified attapulgite with a 25%mass ratio of poly-aluminum ferric chloride was the best.The content of acid-soluble Cd in soil was 29.27%lower than that of the control group,and the content of residual Cd in soil was 24.32%higher than that of CK.The environmental risk factor was 24.15%and was at the lowest level.