电动法联合铁基非晶渗透反应墙修复铜污染土壤

Remediation of Copper Contaminated Soil by Electrokinetic Method Combined with Iron-based Amorphous Osmotic Reaction Barrier

首次采用铁基非晶合金作为渗透反应墙材料联合电动法(EK)修复冶炼厂周边受铜污染的农田土壤。在模拟土壤试验中,首先进行了以Fe_(78)Si_(9)B_(13)^(AP)非晶粉末和零价铁(ZVI)为渗透反应墙以及无渗透反应墙的电动反应。通过土壤连续浸提分析电动过程中Cu^(2+)的迁移转化性能。Fe_(78)Si_(9)B_(13)^(AP)-EK修复后总铜去除率最高可达82.7%,ZVI-EK可达74.9%,而单纯EK仅为67.5%。通过反应机理的探究发现,Fe_(78)Si_(9)B_(13)^(AP)表面的产物层存在大量的垂直于反应界面的孔道结构,能够将Cu^(2+)快速传递到反应界面并被还原为稳定的Cu0,及时消除了由于Cu^(2+)的积累所产生的反向电势。在此基础上选用最佳试验组Fe_(78)Si_(9)B_(13)^(AP)-EK修复实际铜污染土壤。结果显示,此方法的修复效果受污染土壤中铜的化学形态的影响较大,迁移态中铜的去除率仍保持在65.2%。因此,Fe_(78)Si_(9)B_(13)^(AP)有望取代ZVI作为新型环境功能材料应用于土壤修复领域。

Fe-based amorphous alloy was used as osmotic barrier combined electrokinetic method(EK)to repair farmland soil contaminated by copper for the first time.In the experiment of simulating the actual external conditions,electrokinetic reactions with Fe_(78)Si_(9)B_(13)^(AP) amorphous powder and zero-valent iron(ZVI)as osmotic reaction barrier and no osmotic reaction barrier were carried out respectively.Migration and transformation performance of Cu^(2+)during electrokinetic process was analyzed by continuous soil extraction.The results show that content of total copper in soil in Fe_(78)Si_(9)B_(13)^(AP)-EK can be reduced to 17.3%,and ZVI-EK can be reduced to 25.1%,while EK alone can only be reduced to 32.5%.It is found that there are a large number of vertical and reaction interface pore structures in the product layer on the surface of Fe_(78)Si_(9)B_(13)^(AP),which promotes mass transfer process of Cu^(2+),transforms transferable Cu^(2+)into stable Cu0,and eliminates the reverse potential caused by accumulation of Cu^(2+)in time.On this basis,the best experimental group Fe_(78)Si_(9)B_(13)^(AP)-EK was selected to remediate the actual copper contaminated soil.The results show that remediation effect of this method is greatly affected by chemical form of copper in contaminated soil,and removal rate of copper in migration state is 65.2%.Therefore,Fe_(78)Si_(9)B_(13)^(AP) is expected to replace ZVI as a new environmental functional material in field of soil remediation.