Yin Xue, Chen Jia-Jun, Lü Ce
Huan Jing Ke Xue. 2014 Feb;35(2):733-9.
Na2 EDTA (EDTA) has been extensively applied in remediation of soil contaminated by heavy metals (HMs). However, it poses a threat to the environment due to its difficulty of degradation. In addition, it is of great importance to clarify the morphological distribution of these metals in soil, as it is related to the environmental risk of contaminated sites. Thus, in order to cut back the use of EDTA, a series of batch washing experiments were conducted to evaluate the removal of arsenic, cadmium, copper, and lead from the contaminated soil collected in a chemical plant. Furthermore, adopting the optimal ratio of EDTA/EDDS, the change of morphological distribution of HMs before and after washing was studied. The results indicated that the removal of arsenic, cadmium and lead reached the maximum when the ratio of EDTA/EDDS was 7:3 and the optimal value was 12.67%, 38.71% and 31.09%, respectively. The removal of copper reached 16.91% at an EDTA/EDDS ratio of 9:1. After washing, the absolute Fe-Mn oxide fraction concentration of arsenic was higher, which would increase the environmental risk; the morphological fraction distribution of cadmium was similar to the original soil; the removal of copper and lead was mainly derived from the Fe-Mn oxide fraction; as to lead, the absolute concentration of Fe-Mn oxide fraction decreased dramatically, was and the same was observed for the percentage in the organic fraction. Employing the compounded system, the removal of HMs could be improved, and meanwhile the amounts of bioavailable HMs declined. Hence, it is beneficial for providing theoretical support for HMs remediation.
乙二胺四乙酸二钠（EDTA）已被广泛应用于重金属污染土壤的修复。然而，由于其难以降解，对环境构成威胁。此外，明确这些金属在土壤中的形态分布非常重要，因为这与污染场地的环境风险相关。因此，为了减少EDTA的使用，进行了一系列批次冲洗实验，以评估从一家化工厂采集的污染土壤中去除砷、镉、铜和铅的效果。此外，采用EDTA/乙二胺二琥珀酸（EDDS）的最佳比例，研究了冲洗前后重金属形态分布的变化。结果表明，当EDTA/EDDS比例为7:3时，砷、镉和铅的去除率达到最大值，最佳值分别为12.67%、38.71%和31.09%。在EDTA/EDDS比例为9:1时，铜的去除率达到16.91%。冲洗后，砷的铁锰氧化物结合态绝对浓度较高，这会增加环境风险；镉的形态分布与原始土壤相似；铜和铅的去除主要来自铁锰氧化物结合态；对于铅，铁锰氧化物结合态的绝对浓度显著下降，有机结合态中的百分比也出现同样情况。采用复合体系可以提高重金属的去除率，同时生物可利用的重金属含量下降。因此，这有利于为重金属修复提供理论支持。
