利用螯合剂同时去除土壤中重金属、砷及氟化物的技术研究

选取6种萃取剂甘氨酸、谷氨酸、半胱氨酸、EDTA、柠檬酸和硫脲,对受重金属污染的土样以及土样中As、氟离子进行萃取分析.结果表明：EDTA对土壤中的Pb、Cr、Cu、Cd萃取效果最佳,萃取能力大小为Pb〉Cr〉Cu〉Cd;柠檬酸对土壤中Mn、Zn萃取效果最好.设定0、2.5、5、10、20、50 mmol/L的萃取液浓度,对土样中的As、氟离子进行萃取实验.萃取液的浓度越高,萃取的效果越好;50 mmol/L谷氨酸对于As的萃取效果最好,其萃取效果约为EDTA的1.8倍;50 mmol/L的半胱氨酸对于氟离子的萃取效果最佳,远远大于其他萃取液.EDTA对于重金属污染的萃取较好,但必须考虑其对土壤修复的二次污染;而对于As、氟离子的萃取,谷氨酸和半胱氨酸相应为较好的选择.

A Technique for Simultaneous Removal of Heavy Metals,Arsenic and Fluoride from Contaminated Soil by Chelating Agents

A batch experiment was conducted to investigate extracting efficiency of six extracting agents （glycine, glutamic, cysteine, EDTA, Citric scid and thiourea） to heavy metals, arsenic and fluorinion in contaminated soils. The result showed that the best extracting efficiency of Pb, Cr, Cu, Cd and Mn, Zn were EDTA and Citric acid, respectively. The extracting efficiency of EDTA to heavy metals in an order was Pb〉Cr〉 Cu 〉Cd. For the extracting analysis of arsenic and fluorinion, the concentration of extracting agents is decided to be 0, 2.5, 5, 10, 20, 50 mmol/L. The higher concentration of extracting agents was, the better extracting efficiency was. The best extracting efficiency of arsenic was glutamic with concentration of 50 mmol/L and is almost 1.8 times of EDTA. For the fluorinion, cysteine with concentration of 50 mmol/L was best, the extracting efficiency was much better than other extracting agents. In one word, EDTA is of relatively good extracting efficiency to heavy metals but the secondary pollution must be taken into account; glutamic and cysteine are good choices for extraction of arsenic and fluorinion.