冠醚-离子液体体系对水相中铀酰离子的萃取

Investigation on extraction of uranium ions from aqueous phase using crown ether-ionic liquid systems

以二环己基-18-冠醚-6(DCH18C6)为萃取剂,一系列离子液体为溶剂的冠醚-离子液体萃取体系对水相中铀酰离子(UO2+2)进行萃取实验。结果表明:UO2+2在1-丁基-3-甲基咪唑双三氟磺酰亚胺盐([C4min]NTf2)体系的去除效率明显高于六氟磷酸盐类(PF-6)离子液体。在水相中当硝酸浓度在3 mol·L^(-1)左右时萃取效率最高,体系的萃取效率随着萃取剂浓度的增加而变大,共存离子的加入会降低体系的萃取效率,但是当加入的是硝酸根离子时,萃取率会相应增大。根据实验结果分析可以判断此萃取体系主要为阳离子交换过程。

The extraction of uranium ions using DCH18C6 as the extractant and various ionic liquids（ ILs） as solvents was investigated. The extraction efficiency in an NTf2^-ionic liquid system was found to be distinctly higher than that in a PF6^-system,and the extraction efficiency increases with the concentration of the extractant.The addition of coexisting ions decreases the extraction efficiency,whereas the presence of nitrate ions has the opposite effect. Moreover,the highest extraction ratio for the extraction of UO2^2 ＋from 3 mol·L^-1nitric acid is achieved by 0. 1 mol·L^-1DCH18C6. The findings confirm that the extraction proceeds mainly via a cation-exchange mechanism.