| EDTA与柠檬酸复配洗涤修复多重金属污染土壤效果研究 |
| 摘要点击 4246 全文点击 1867 投稿时间：2013-12-10 修订日期：2014-02-28 |
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| 中文关键词 土壤洗涤 重金属 EDTA 柠檬酸 复配 形态 |
| 英文关键词 soil washing heavy metals EDTA citric acid compound speciation |
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| 中文摘要 |
| 乙二胺四乙酸二钠（EDTA）和柠檬酸是土壤重金属污染洗涤修复中最常用的洗涤剂，现以某化工场多种重金属污染土壤为对象，开展室内搅拌实验考察EDTA与柠檬酸复配对As、 Cd、 Cu及Pb的洗脱效果和最佳洗涤条件下重金属形态变化. 结果表明，在最佳复配比（EDTA与柠檬酸的摩尔比为1：1）条件下，当混合液pH为3、 洗涤时间为30 min、 搅拌强度为150 r·min-1和液固比为5：1时，As、 Cd、 Cu及Pb去除率可达11.72%、 43.39%、 24.36%和27.17%. 洗涤后，酸溶解态As、 Cu浓度增加，相应提高了其有效态所占比例. 铁锰氧化态Cu对浓度的削减贡献最大. Cd的酸溶解态、 铁锰氧化态、 氧化物结合态所占比例均有所降低. 洗涤修复后重金属形态变化会带来一定环境风险，实际工程应用中应充分考虑. |
| 英文摘要 |
| 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·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. |
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