Yin Xue, Chen Jia-Jun, Cai Wen-Min
Huan Jing Ke Xue. 2014 Aug;35(8):3096-101.
As commonly used eluents, Na2EDTA (EDTA) and citric acid (CA) have been widely applied in remediation of soil contaminated by heavy metals. In order to evaluate the removal of arsenic, cadmium, copper, and lead in the contaminated soil collected in a chemical plant by compounding EDTA and CA, a series of stirring experiments were conducted. Furthermore, the changes in speciation distribution of heavy metals before and after washing were studied. The results showed that, adopting the optimal molar ratio of EDTA/CA (1:1), when the pH of the solution was 3, the stirring time was 30 min, the stirring rate was 150 r x min(-1) and the L/S was 5:1, the removal rates of arsenic, cadmium, copper and lead could reach 11.72%, 43.39%, 24.36% and 27.17%, respectively. And it was found that after washing, for arsenic and copper, the content of acid dissolved fraction rose which increased the percentage of available contents. Fe-Mn oxide fraction mainly contributed to the removal of copper. As for cadmium, the percentages of acid dissolved fraction, Fe-Mn oxide fraction and organic fraction also decreased. In practical projects, speciation changes would pose certain environmental risk after soil washing, which should be taken into consideration.
作为常用洗脱剂，乙二胺四乙酸二钠（EDTA）和柠檬酸（CA）已广泛应用于重金属污染土壤的修复。为了评估通过复合EDTA和CA对某化工厂采集的污染土壤中砷、镉、铜和铅的去除效果，进行了一系列搅拌实验。此外，还研究了洗涤前后重金属形态分布的变化。结果表明，采用EDTA/CA最佳摩尔比（1:1），当溶液pH值为3，搅拌时间为30分钟，搅拌速率为150转×分钟⁻¹且液固比为5:1时，砷、镉、铜和铅的去除率分别可达11.72%、43.39%、24.36%和27.17%。并且发现洗涤后，对于砷和铜，酸溶态含量上升，有效态含量百分比增加。铁锰氧化物态是铜去除的主要贡献形态。对于镉，酸溶态、铁锰氧化物态和有机态的百分比也降低。在实际工程中，土壤洗涤后形态变化会带来一定环境风险，应予以考虑。
