| 螯合剂复配对实际重金属污染土壤洗脱效率影响及形态变化特征 |
| 摘要点击 1892 全文点击 1141 投稿时间：2013-05-23 修订日期：2013-10-21 |
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| 中文关键词 土壤洗涤 重金属 EDTA EDDS 复配 形态 |
| 英文关键词 soil washing heavy metals EDTA EDDS compound morphology |
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| 中文摘要 |
| 乙二胺四乙酸二钠 （EDTA）是土壤重金属污染洗涤修复中最常用的洗涤剂，然而其难降解性会对环境产生不利影响. 而污染场地重金属形态分布对其环境风险至关重要. 以某化工场地多种重金属污染土壤为对象，为减少EDTA用量，开展室内振荡实验考察EDTA与EDDS复配对As、Cd、Cu及Pb的洗脱效果和最佳复配比条件下洗涤前后重金属形态变化. 结果表明在最优洗脱条件下，As、Cd和Pb去除率在EDTA：EDDS=7：3时达到最高，分别为12.67%、38.71%和31.09%；Cu在复配比为9：1时可达16.91%. 洗涤后，As的铁锰氧化态含量升高，会增加一定的环境风险；Cd的形态分布大体与原土一致；Cu和Pb的洗脱主要来自铁锰氧化态，其中Pb的铁锰氧化态洗脱量最大，而有机结合态所占百分比降幅最显著. 复配体系不仅对4种重金属的洗脱率有一定提升，洗涤后重金属有效态比例也有所降低，对土壤重金属污染的修复具有指导意义. |
| 英文摘要 |
| Na2EDTA(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. |
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