三种淋洗剂淋洗脱除土壤中Cr、Cd的效果研究

Study on the effectiveness of three drenchers for the removal of Cr and Cd from soil by drenching

采用振荡淋洗的方式研究柠檬酸(CA)、硝酸和乙二胺四乙酸二钠(EDTA-2Na)对Cr、Cd复合污染土壤的淋洗脱除效果。结果表明,Cr和Cd的去除率随着淋洗剂浓度的增加而增长,在最佳的淋洗剂浓度(CA浓度为0.08 mol/L、HNO_(3)为0.6 mol/L、EDTA-2Na为0.1 mol/L),最佳液固比为20∶1,最佳的淋洗时间为12 h,HNO_(3)的淋洗效率最高,对Cr、Cd的淋洗率分别为72.09%和92%;CA相比于EDTA-2Na对Cr有更好的去除效果,而EDTA-2Na对Cd有更好的去除效果。淋洗主要是化学过程,CA对Cr、Cd从土壤中的解吸主要是酸溶作用和络合作用,EDTA-2Na是通过螯合作用,HNO_(3)则主要是通过强酸性溶解难溶金属化合物。

The effect of citric acid(CA),nitric acid(HNO_(3)) and disodium ethylenediaminetetraacetic acid(EDTA-2Na)on the removal of Cr and Cd from the composite contaminated soil was studied by oscillatory drenching.The results showed that the removal rate of Cr and Cd increased with the increase of drencher concentration,and at the optimum drencher concentration(0.08 mol/L for CA,0.6 mol/L for HNO_(3) and 0.1 mol/L for EDTA-2Na),the optimum liquid-solid ratio was 20∶1,and the optimum drenching time was 12 h.The highest drenching efficiency was achieved by HNO_(3) with 72.09%and 92%for Cr and Cd,respectively;CA had a better removal effect on Cr than EDTA-2Na,while EDTA-2Na had a better removal effect on Cd.Drench the desorption of Cr and Cd from soil by CA was mainly by acid solubilization and complexation,while EDTA-2Na was by chelation,and HNO_(3) was mainly by strong acid solubilization of insoluble metal compounds.