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Title: Separation of fission products based on ionic liquids: Task-specific ionic liquids containing an aza-crown ether fragment

Abstract

A new class of task-specific ionic liquids (TSILs) based on the covalent attachment of imidazolium cations to a monoaza-crown ether fragment has been synthesized and characterized. The efficacy of these TSILs for the biphasic extraction of Cs(+) and Sr(2+) from aqueous solutions has been evaluated. The extraction properties of these TSILs can be influenced by the structures of the covalently attached imidazolium cations, which highlight the possibilities to enhance or tune the selectivities of crown ethers toward target ionic species through the covalent coupling with the imidazolium cations. (c) 2005 Elsevier B.V. All rights reserved.

Authors:
 [1];  [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1118756
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Alloys and Compounds; Journal Volume: 418; Journal Issue: 1-2
Country of Publication:
United States
Language:
English

Citation Formats

Luo, Huimin, Dai, Sheng, Bonnesen, Peter V, and Buchanan III, A C. Separation of fission products based on ionic liquids: Task-specific ionic liquids containing an aza-crown ether fragment. United States: N. p., 2005. Web.
Luo, Huimin, Dai, Sheng, Bonnesen, Peter V, & Buchanan III, A C. Separation of fission products based on ionic liquids: Task-specific ionic liquids containing an aza-crown ether fragment. United States.
Luo, Huimin, Dai, Sheng, Bonnesen, Peter V, and Buchanan III, A C. 2005. "Separation of fission products based on ionic liquids: Task-specific ionic liquids containing an aza-crown ether fragment". United States. doi:.
@article{osti_1118756,
title = {Separation of fission products based on ionic liquids: Task-specific ionic liquids containing an aza-crown ether fragment},
author = {Luo, Huimin and Dai, Sheng and Bonnesen, Peter V and Buchanan III, A C},
abstractNote = {A new class of task-specific ionic liquids (TSILs) based on the covalent attachment of imidazolium cations to a monoaza-crown ether fragment has been synthesized and characterized. The efficacy of these TSILs for the biphasic extraction of Cs(+) and Sr(2+) from aqueous solutions has been evaluated. The extraction properties of these TSILs can be influenced by the structures of the covalently attached imidazolium cations, which highlight the possibilities to enhance or tune the selectivities of crown ethers toward target ionic species through the covalent coupling with the imidazolium cations. (c) 2005 Elsevier B.V. All rights reserved.},
doi = {},
journal = {Journal of Alloys and Compounds},
number = 1-2,
volume = 418,
place = {United States},
year = 2005,
month = 1
}
  • This work explores the performance of a series of ionic liquids that incorporate a nitrile-containing anion paired to 1-alkyl-3-methylimidazolium cations in tailoring the selectivity and permeance of supported ionic liquid membranes for CO2/N2 separations. The permeance and selectivity of three ionic liquids, each with an increasing number of nitrile groups in the anion (i.e., two, three, and four), were measured using a non-steady-state permeation method. By predictably varying the molar volume and viscosity of the ionic liquids, we show that the solubility, selectivity, and permeance can be optimized for CO2/N2 separation through controlled introduction of the nitrile functionality into themore » anion. Of the three nitrile-based ionic liquids studied, 1-ethyl-3-methylimidazolium tetracyanoborate, [emim][B(CN)4], showed the highest permeance with a value of 2.55 10 9 mol/(m2 Pa s), a magnitude 30% higher than that of the popular ionic liquid [emim][Tf2N]. This same nitrile-bearing ionic liquid also exhibited a high CO2/N2 selectivity of approximately 53. Additionally, the carbon dioxide solubility for each ionic liquid was measured at room temperature with [emim][B(CN)4] again exhibiting the highest CO2 solubility. Results from our study of the nitrile-based ionic liquids can be rationalized in terms of regular solution theory wherein the selectivity and permeance of a given SILM system are largely determined by the molar volume and viscosity of the corresponding ionic liquid phase.« less
  • The transfer of strontium ion from acidic nitrate media into a series of 1-alkyl-3-methylimidazolium-based room-temperature ionic liquids containing dicyclohexano-18-crown-6 is shown to proceed via cation-exchange, in contrast to conventional solvents such as alkan-1-ols, in which extraction of a strontium nitrato-crown ether complex is observed.
  • Nuclear magnetic resonance (NMR) spectroscopy has been used to study hydrogen-bonding interactions between water, associated and dissociated acids (i.e., nitric and methanesulfonic acids), and the constituent ions of several water-immiscible room-temperature ionic liquids (ILs). In chloroform solutions also containing a crown ether (CE), water molecules strongly associate with the IL ions, and there is rapid proton exchange between these bound water molecules and hydronium associated with the CE. In neat ILs, the acids form clusters differing in their degree of association and ionization, and their interactions with the CEs are weak. The CE can either promote proton exchange between differentmore » clusters in IL solution when their association is weak or inhibit such exchange when the association is strong. Even strongly hydrophobic ILs are shown to readily extract nitric acid from aqueous solution, typically via the formation of a 1:1:1 {l_brace}H{sub 3}O{sup +} {center_dot} CE{r_brace}NO{sub 3}{sup -} complex. In contrast, the extraction of methanesulfonic acid is less extensive and proceeds mainly by IL cation-hydronium ion exchange. The relationship of these protic equilibria to the practical application of hydrophobic ILs (e.g., in spent nuclear fuel reprocessing) is discussed.« less