碳酸钙对铜铅铬复合污染土壤的修复机制  

Remediation of Cu(Ⅱ),Pb(Ⅱ)and Cr(Ⅲ)contaminated soils with CaCO_3

作　　者：马荣生[1] 陈杰[1] 夏鹏[1] 王学江[1] 

机构地区：[1]同济大学环境科学与工程学院/污染控制与资源化研究国家重点实验室,上海200092

出　　处：《西北农林科技大学学报（自然科学版）》2017年第1期119-123,130,共6页Journal of Northwest A&F University(Natural Science Edition)

基　　金：国家"863"计划项目"污泥土地利用风险控制综合技术研发与示范(2012AA063608-03)";国家国际合作专项"污水厂污泥与餐厨垃圾高级厌氧消化技术及应用合作研究(2014DFA91650)"

摘　　要：【目的】探讨碳酸钙对铜、铅、铬复合污染土壤的钝化效果及修复机制。【方法】利用碳酸钙对复合污染土壤中的Cu、Pb和Cr进行钝化处理,以重金属有效态含量的减少对碳酸钙投加量进行优化,并对土壤中Cu、Pb和Cr有效态含量的减少进行动力学模拟;运用改进的BCR分级提取法对土壤中的3种重金属进行形态分析,并对修复后的土壤进行X射线衍射(XRD)分析,初步探讨碳酸钙对复合污染土壤中3种重金属的钝化机制。【结果】碳酸钙投加量为50g/kg时,其对Cu、Pb和Cr污染土壤的修复效果最佳,此时Cu、Pb和Cr有效态含量减少的动力学符合Elovich方程;钝化28d后,与空白对照组(未添加CaCO3)相比,Cu、Pb和Cr 3种重金属的可交换态含量分别减少28.2%,31.9%和74.8%,可还原态含量分别增加2.9,2.0和1.3倍,残渣态含量分别增加5.8,2.7和1.3倍,可氧化态含量无明显变化。【结论】碳酸钙对土壤中Cu、Pb、Cr 3种重金属的有效态含量有明显钝化效果,其一方面通过提高土壤pH提升土壤对重金属的吸附性能,促进重金属生成Cu3(OH)2(CO3)2等沉淀;另一方面其直接与重金属生成更难溶的PbCO3等沉淀,促进土壤中重金属的钝化。【Objective】This study investigated the passivation effect and remediation mechanism of CaCO_3 on Cu,Pb and Cr contaminated soils.【Method】CaCO_3was added to immobilize heavy metals in contaminated soils.The best CaCO_3 dosage was chosen according to the immobilization efficiency,and dynamic simulation of the reduction of Cu,Pb and Cr effective contents in soil was carried out.After amendment of CaCO_3,the fractions of heavy metals were measured,and the crystal structure of soil was studied using Xray diffraction（XRD）technique.【Result】CaCO_3performed the best immobilization effect with the dose of50g/kg,and the reduction of Cu,Pb and Cr effective contents followed the Elovich equation.After 28days＇ immobilization,the exchangeable contents of Cu,Pb and Cr were reduced by 28.2%,31.9% and74.8% compared with the control,the reduction contents increased by 2.9,2.0and 1.3times,the residual contents increased by 5.8,2.7and 1.3times,while the oxidation contents did not change much.【Conclusion】CaCO_3reduced the effective contents of heavy metals in soil by improving soil pH to improve soil ad-sorption of heavy metals and promote precipitation of heavy metals,and reacting with heavy metals in soil.

关 键 词：重金属污染 土壤修复 形态分析 钝化机制 

分 类 号：X53[环境科学与工程—环境工程]