Environment Research Institute, Shandong University, Qingdao, 266237, China.
School of Environmental Science and Engineering, Shandong University, Qingdao, 266237, China.
Environ Sci Pollut Res Int. 2022 Apr;29(20):29818-29829. doi: 10.1007/s11356-021-18480-5. Epub 2022 Jan 7.
Ethylenediaminetetraacetic acid (EDTA) washing has been used extensively to remediate heavy metal-contaminated soils. Electrochemical reduction treatment of spent washing solution is an effective method of EDTA regeneration. However, at present, these two technologies are usually regarded as two independent treatment processes. This research raised a new heavy metal-contaminated soil treatment strategy-a combination technique of coupled EDTA washing and electrochemical reduction. We speculated that the combination of EDTA washing and electroreduction treatment could improve the efficiency of Cd and Pb removal from contaminated soil. In this study, the removal performance and mechanisms of Cd and Pb under different current conditions were investigated based on a coupling of EDTA washing and electrochemical reduction. The combination technique can increase Cd and Pb removal efficiencies by 13.37-15.24% and 14.91-27.05%, respectively, compared with EDTA washing alone. Sequential extraction analysis showed that the reducible fraction improved metal removal efficiency. The percentage of metal removed increased with an increased current value and EDTA concentration. In addition, pulse current mode removed more Cd and Pb than continuous current, although the difference was not significant (p > 0.05). However, pulse current could effectively eliminate the cathodic hydrogen evolution reaction, resulting in a further heavy metal deposition at the cathode. The combination technique exhibited enhanced removal efficiency due to EDTA regeneration in the suspension and the cathodic reduction reaction. The most cost-effective treatment in 48 h was a pulse current mode of 32 min on/16 min off-32 mA-EDTA-10 mM, where 47.56% of Cd and 77.00% of Pb were removed from the soil with an electric energy consumption of 8.24 Wh.
乙二胺四乙酸（EDTA）洗涤已广泛用于修复重金属污染土壤。电化学还原处理用过的洗涤液是 EDTA 再生的有效方法。然而，目前这两种技术通常被视为两个独立的处理过程。本研究提出了一种新的重金属污染土壤处理策略，即 EDTA 洗涤与电化学还原耦联技术。我们推测，EDTA 洗涤与电还原处理的结合可以提高受污染土壤中 Cd 和 Pb 去除的效率。本研究基于 EDTA 洗涤与电化学还原的偶联，考察了不同电流条件下 Cd 和 Pb 的去除性能及其机制。与单独的 EDTA 洗涤相比，该组合技术可分别将 Cd 和 Pb 的去除效率提高 13.37%-15.24%和 14.91%-27.05%。顺序提取分析表明，可还原态分数提高了金属去除效率。金属去除率随电流值和 EDTA 浓度的增加而增加。此外，尽管脉冲电流比连续电流去除了更多的 Cd 和 Pb，但差异不显著（p>0.05）。然而，脉冲电流可以有效地消除阴极析氢反应，从而导致阴极处进一步重金属沉积。由于悬浮液中 EDTA 的再生和阴极还原反应，该组合技术表现出更高的去除效率。在 48 小时内，最具成本效益的处理方式是在 32 mA-EDTA-10 mM 条件下采用 32 分钟开/16 分钟关的脉冲电流模式，其中土壤中 47.56%的 Cd 和 77.00%的 Pb 被去除，电能消耗为 8.24 Wh。
