Agronomy Department, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia.
J Hazard Mater. 2011 Aug 30;192(2):714-21. doi: 10.1016/j.jhazmat.2011.05.077. Epub 2011 May 31.
Recycling of chelant decreases the cost of EDTA-based soil washing. Current methods, however, are not effective when the spent soil washing solution contains more than one contaminating metal. In this study, we applied electrochemical treatment of the washing solution obtained after EDTA extraction of Pb, Zn and Cd contaminated soil. A sacrificial Al anode and stainless steel cathode in a conventional electrolytic cell at pH 10 efficiently removed Pb from the solution. The method efficiency, specific electricity and Al consumption were significantly higher for solutions with a higher initial metal concentration. Partial replacement of NaCl with KNO(3) as an electrolyte (aggressive Cl(-) are required to prevent passivisation of the Al anode) prevented EDTA degradation during the electrolysis. The addition of FeCl(3) to the acidified washing solution prior to electrolysis improved Zn removal. Using the novel method 98, 73 and 66% of Pb, Zn and Cd, respectively, were removed, while 88% of EDTA was preserved in the treated washing solution. The recycled EDTA retained 86, 84 and 85% of Pb, Zn and Cd extraction potential from contaminated soil, respectively.
螯合剂的回收降低了基于 EDTA 的土壤洗脱的成本。然而，当用过的土壤洗脱溶液中含有多种污染金属时，目前的方法就不那么有效了。在这项研究中，我们应用电化学处理从 Pb、Zn 和 Cd 污染土壤的 EDTA 萃取后获得的洗脱溶液。在 pH 值为 10 的传统电解槽中，牺牲的 Al 阳极和不锈钢阴极有效地从溶液中去除 Pb。对于初始金属浓度较高的溶液，该方法的效率、比电耗和 Al 消耗量显著更高。用 KNO3 部分替代 NaCl 作为电解质（需要有腐蚀性的 Cl-来防止 Al 阳极钝化）可以防止 EDTA 在电解过程中降解。在电解之前，将 FeCl3 添加到酸化的洗脱溶液中，可以提高 Zn 的去除率。使用新方法，Pb、Zn 和 Cd 的去除率分别为 98%、73%和 66%，而处理后的洗脱溶液中保留了 88%的 EDTA。回收的 EDTA 分别保留了从污染土壤中提取 Pb、Zn 和 Cd 的 86%、84%和 85%的潜力。
