Related Experiment Video
Updated: Aug 24, 2026

Synthesis of Ionic Liquid Based Electrolytes, Assembly of Li-ion Batteries, and Measurements of Performance at High Temperature
Published on: December 20, 2016
Solvent extraction of sr2+ and cs+ based on room-temperature ionic liquids containing monoaza-substituted crown
Huimin Luo1, Sheng Dai, Peter V Bonnesen
1Nuclear Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA. luoh@ornl.gov
Abstract:
A series of N-alkyl aza-18-crown-6 ethers were synthesized and characterized by NMR spectroscopy and mass spectrometry. These monoaza-substituted crown ethers in ionic liquids were investigated as recyclable extractants for separation of Sr(2+) and Cs(+) from aqueous solutions. The pH-sensitive complexation capability of these ligands allows for a facile stripping process to be developed so that both macrocyclic ligands and ionic liquids can be reused. The extraction efficiencies and selectivities of these monoaza-substituted crown ethers for Na(+), K(+), Cs(+), and Sr(2+) were studied in comparison to those of dicyclohexano-18-crown-6 under the same conditions. The extraction selectivity order for dicyclohexano-18-crown-6 in the ionic liquids investigated here was K(+) >> Sr(2+) > Cs(+) > Na(+). The extraction selectivity order for N-alkyl aza-18-crown-6, in which the alkyl group is varied systematically from ethyl to n-dodecyl, was Sr(2+) >> K(+) > Cs(+) > Na(+) in 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]amide and 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]amide and K(+) > Sr(2+) > Cs(+) > Na(+) in 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] amide and 1-octyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]amide. The strong dependence of selectivity on the type of ionic liquid indicates an important role played by solvation in solvent extraction processes based on ionic liquids. The optimization of macrocyclic ligands and ionic liquids led to an extraction system that is highly selective toward Sr(2+).
Related Concept Videos
Crown Ethers
Ion Exchange
Preparation and Reactions of Sulfides
Extraction: Advanced Methods
Solvents
A...
Ion-Exchange Chromatography

