淋洗与电化学还原联用处理镉-铅污染土壤

Remediation of Cd-Pb contaminated soil by coupled soil washing and electrochemical reduction

为探究螯合剂淋洗与电化学还原联用能否提高土壤重金属去除效率,提出了一种基于两种技术联用的处理方法.比较了淋洗与联用技术Cd和Pb的去除效率,探究了使用联用技术时土壤悬液重金属的传质机制,分析了不同螯合剂处理的成本效益.研究发现,联用技术能有效地提高重金属的去除效率,协同增强效应与螯合剂的螯合能力及再生能力有关.氨基多羧酸类螯合剂最大可将Cd和Pb的去除效率提高15.24%和27.05%,小分子有机酸最大可将Cd和Pb的去除效率提高5.31%和10.24%.结果表明,氨基多羧酸类螯合剂更适用于联用修复体系.认为其经济有效的修复手段是采用EDTA淋洗与电化学还原联用,可以将46.60%的Cd和76.93%的Pb从土壤中去除.

This study proposed a combination technique to explore whether the coupling of chelating agent washing and electrochemical reduction can improve the heavy metal removal efficiency. The removal performance, mass transport mechanisms and economic benefits were investigated based on both a coupling strategy and separate soil washing. The combination technique could effectively improve the removal efficiency of heavy metals, and the synergistic enhancement effect was related to the chelating ability and regeneration ability of the chelating agent. The aminopolycarboxylic acids could increased the removal efficiency of Cd and Pb by 15.24% and 27.05%, respectively. The low-molecular-weight organic acids increased the removal efficiency of Cd and Pb by 5.31% and 10.24%, respectively. Aminopolycarboxylic acids were more suitable for the combination system. The most cost-effective treatment in 48h was coupled EDTA washing and electrochemical reduction, where 46.60% of Cd and 76.93% of Pb were removed from the soil.