Experimental Study on Leaching Efficiency of Chemical Leaching Method for Heavy Metal Contaminated Soil

采用乙二胺四乙酸(EDTA)及柠檬酸(CA)复配淋洗剂，固定淋洗液与土壤的固液比、淋洗时间，探究淋洗液复配浓度、淋洗次数对本项目三种重金属污染土壤的淋洗效果。结果表明，采用1mM EDTA + 1mM CA复配淋洗剂，固液比1:5，淋洗时间0.5 h，淋洗一次时，三种重金属污染土壤的去除率均最佳；在上述淋洗条件下，继续增加淋洗次数，三种重金属污染土壤的去除率均有所提升，但对于高浓度汞污染土壤，仅采用化学淋洗法无法将其有效去除，且淋洗成本较高，因此可考虑结合其它修复技术进行治理。本研究对不同浓度汞污染土壤、重金属砷、钴复合污染土壤淋洗修复工艺和工程应用具有一定的指导意义。Using a compound leaching agent of ethylenediaminetetraacetic acid (EDTA) and citric acid (CA), the solid-liquid ratio and leaching time of the leaching solution and soil were fixed to investigate the leaching effect of the complex concentration and leaching frequency of the leaching solution on the three heavy metal polluted soils in this project. The results showed that the removal rates of the three heavy metal polluted soils were optimal when using a 1mM EDTA + 1mM CA compound leaching agent, with a solid-liquid ratio of 1:5 and a leaching time of 0.5 h, after one leaching; Under the above washing conditions, increasing the washing frequency further improves the removal rates of the three heavy metal polluted soils. However, for high concentration mercury polluted soils, chemical washing alone cannot effectively remove them, and the washing cost is high. Therefore, other remediation techniques can be considered for treatment. This study has certain guiding significance for the leaching and remediation process and engineering application of soils contaminated with different concentrations of mercury, heavy metals arsenic and cobalt.