Evaluation of Hydroxyalkyl-Functionalized Imidazolium-based Ionic Liquids as Solvents for the Extraction of Metal Ions

Abstract

As part of a broader effort to evaluate the suitability of a variety of ionic liquids (ILs) as solvents for the extraction of actinides and fission products, a series of new ILs containing a (1-hydroxyalkyl)-functionalized imidazolium cation have been prepared and characterized. Although certain of their physicochemical properties (e.g., density, liquidus range) remain largely unaffected vs their N,N′-dialkylimidazolium analogs by hydroxyl-functionalization, other characteristics (e.g., hydrophilicity) are measurably changed. In addition, this functionalization has been found to alter the “balance of pathways” among the various routes by which a metal ion may partition between aqueous nitric acid solutions and ionic liquids containing a neutral extractant.

Keywords:

• alkali cations
• alkaline earth cation
• crown ethers
• extraction solvents
• ionic liquids

ACKNOWLEDGEMENTS

This work was supported by the Single Investigator Small Group Research (SISGR) Program of the Office of Basic Energy Sciences of the United States Department of Energy under sub-contract from Brookhaven National Laboratory.

Notes

Uncertainties are based on the 95% confidence interval, where n = 5 measurements of density and n = 4 measurements of water mutual solubility.

ND = not determined.

^a Reference 43.

^b Reference 44.