Contamination of soil with heavy metals has become a significant environmental issue worldwide. In previous studies, a technology that couped EDTA-washing and cathodic reduction technology was developed to further remove heavy metals from soil contaminated with electroplating waste compared with single soil washing technology. Although the method showed a synergistic effect in previous studies, the effect of soil suspension alkalization and the mechanism behind it remain unclear. High soil pH will have an impact on target metal removal, energy consumption and further utilization of soil. In this experimental research, we investigated the efficacy of pH control on coupling soil washing and cathodic reduction to remove multiple heavy metals from soil under various current densities. To alleviate the OH⁻ ions generated by the cathode and improve the reduction efficiency of metals, an automatic pH controller was used, resulting in a significant increase in the removal rate of target metals. The experimental results show that controlling the pH of soil suspension can increase the total removal rate of target metals by 3-6 times. Additionally, the removal efficiency of residual Pb in the soil is increased by about 30%. In terms of ecological risk, pH control could reduce the solubility and mobility of metals by 50%, and the ecological risk was greatly reduced, especially for Zn, from about 90 mg/kg to 50 mg/kg. Further research is needed to explore the mechanism of the synergistic effect and improve the efficiency of this technology for the subsequent development of coupling EDTA-washing and cathodic reduction.

土壤重金属污染已成为世界范围内的重大环境问题。前人研究开发了EDTA洗涤与阴极还原技术相结合的技术，与单一的土壤洗涤技术相比，进一步去除了电镀废料污染土壤中的重金属。尽管该方法在以往的研究中显示出协同效应，但土壤悬浮液碱化的效果及其背后的机制仍不清楚。高土壤 pH 值将对目标金属去除、能源消耗和土壤的进一步利用产生影响。在这项实验研究中，我们研究了 pH 控制对耦合土壤洗涤和阴极还原以在各种电流密度下从土壤中去除多种重金属的功效。减轻 OH ^-阴极产生的离子，提高金属的还原效率，使用自动pH控制器，目标金属的去除率显着提高。实验结果表明，控制土壤悬浮液的pH值可使目标金属的总去除率提高3-6倍。此外，土壤中残留铅的去除效率提高了约30%。在生态风险方面，pH控制可使金属的溶解度和迁移率降低50%，生态风险大大降低，尤其是Zn，从90 mg/kg左右降低到50 mg/kg。需要进一步研究探索协同效应的机理，提高该技术的效率，以用于后续开发耦合EDTA-洗涤和阴极还原。