物理化学学报 >> 2015, Vol. 31 >> Issue (5): 843-851.doi: 10.3866/PKU.WHXB201503202

热力学,动力学和结构化学 上一篇    下一篇

三丁基氧化膦-离子液体体系萃取UO2(NO3)2的机理和选择性

刘海望, 沈兴海, 陈庆德   

  1. 北京大学化学与分子工程学院, 放射化学与辐射化学重点学科实验室, 北京分子科学国家实验室, 北京100871
  • 收稿日期:2015-01-13 修回日期:2015-03-19 发布日期:2015-05-08
  • 通讯作者: 沈兴海 E-mail:xshen@pku.edu.cn
  • 基金资助:

    国家自然科学基金(91226112)资助项目

Extraction Mechanism and Selectivity of UO2(NO3)2 in Tributylphosphine Oxide-Ionic Liquid System

LIU Hai-Wang, SHEN Xing-Hai, CHEN Qing-De   

  1. Beijing National Laboratory for Molecular Sciences, Fundamental Science on Radiochemistry and Radiation Chemistry Laboratory, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
  • Received:2015-01-13 Revised:2015-03-19 Published:2015-05-08
  • Contact: SHEN Xing-Hai E-mail:xshen@pku.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (91226112).

摘要:

研究了三辛基氧化膦(TOPO)和三丁基氧化膦(TBPO)在离子液体(ILs) 1-烷基-3-甲基咪唑双三氟甲基磺酰亚胺盐(CnmimNTf2, n=2, 4, 6, 8)中萃取分离UO2(NO3)2. TOPO-C2mimNTf2和TOPO-C4mimNTf2体系萃取UO2(NO3)2时会出现三相, 而TBPO萃取UO2(NO3)2的萃合物可以很好地溶解在所有离子液体中. 论文也考察了萃取过程中的萃取剂浓度效应、酸效应、盐效应. 水相加入HNO3会降低萃取效率. 盐效应证明了萃取是一种阳离子交换机理. 水相中加入NO3-能够提高U的萃取, 这说明NO3-参与萃取. 选择性研究表明: 除了在高酸度下对Zr 的显著萃取, TBPO-C4mimNTf2萃取体系在低酸度下对U呈现较好的选择性; 去除U后, 在低酸度下该体系对三价Nd 仍保持较好的选择性. 通过定量比较离子液体中NO3-进入量, 电喷雾质谱(ESI-MS)和紫外光谱表征确定了TBPO-CnmimNTf2中萃取机理的差异性. 萃取中存在两种萃合物, 即UO2(TBPO)3(NO3)+和UO2(TBPO)32+, 其中UO2(TBPO)3(NO3)+的比例从C2mimNTf2体系到C8mimNTf2体系逐渐增加.

关键词: 铀, 离子液体, 萃取三相, 萃取选择性, 萃取机理

Abstract:

The extraction of UO2(NO3)2 from aqueous solution was investigated using trioctylphosphine oxide (TOPO) and tributylphosphine oxide (TBPO) in ionic liquids (ILs) (CnmimNTf2, n=2, 4, 6, 8). A third phase was formed in the TOPO-C2mimNTf2 and TOPO-C4mimNTf2 extraction systems, whereas the extracted species of TBPO-CnmimNTf2 (n=2, 4, 6, 8) were well soluble in all ILs. The influence of the concentrations of the extractant, nitric acid, and salt on the extraction efficiency was also investigated. Adding HNO3 to the aqueous phase decreased the extraction efficiency. The effect of salt indicates the presence of a cation-exchange mechanism in the extraction. The addition of NO3 - in the aqueous phase increased the extraction efficiency of U, which indicates that NO3 - participates in the extraction. Selective extraction research indicates that TBPO-C4mimNTf2 exhibits good selectivity for U at low acid concentration despite the significant extraction efficiency on Zr at high acid concentration. After removing U, TBPO-C4mimNTf2 still showed high selectivity for Nd at low acid concentration. We also confirmed the difference of the extraction mechanisms among TBPO-CnmimNTf2 by quantitative measurement of NNO3 - in ILs, electrospray ionization mass spectroscopy (ESI- MS), and UV spectroscopy. There are two extraction species (UO2(TBPO)3(NO3)+ and UO2(TBPO)32+) and the proportion of UO2(TBPO)3(NO3)+ increases from C2mimNTf2 to C8mimNTf2.

Key words: Uranium, Ionic liquid, Extraction third phase, Extraction selectivity, Extraction mechanism

MSC2000: 

  • O642