Article

The distillation and volatility of ionic liquids

The QUILL Centre, The Queen's University of Belfast, Stranmillis Road, Belfast BT9 5AG, UK.
Nature (Impact Factor: 42.35). 03/2006; 439(7078):831-4. DOI: 10.1038/nature04451
Source: PubMed

ABSTRACT It is widely believed that a defining characteristic of ionic liquids (or low-temperature molten salts) is that they exert no measurable vapour pressure, and hence cannot be distilled. Here we demonstrate that this is unfounded, and that many ionic liquids can be distilled at low pressure without decomposition. Ionic liquids represent matter solely composed of ions, and so are perceived as non-volatile substances. During the last decade, interest in the field of ionic liquids has burgeoned, producing a wealth of intellectual and technological challenges and opportunities for the production of new chemical and extractive processes, fuel cells and batteries, and new composite materials. Much of this potential is underpinned by their presumed involatility. This characteristic, however, can severely restrict the attainability of high purity levels for ionic liquids (when they contain poorly volatile components) in recycling schemes, as well as excluding their use in gas-phase processes. We anticipate that our demonstration that some selected families of commonly used aprotic ionic liquids can be distilled at 200-300 degrees C and low pressure, with concomitant recovery of significant amounts of pure substance, will permit these currently excluded applications to be realized.

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    • "During the last decade, ionic liquids (ILs) have been emerging at the cutting edge of modern chemistry as new alternative solvents [1]. Owing to their exceptional combination of properties (negligible vapor pressure [2], high ion conductivity [3], high thermal stability [4], and low flammability [5]), ILs have been used to promote more efficient processes or develop novel functional materials in a plethora of different technological fields such as electrochemistry [6], biotechnology [7], analytical chemistry [8], catalysis [9], energy [10], nanotechnology [11], among others. In particular, ILs have attracted much attention as alternative media for CO 2 capture and separation processes [12] [13] [14] [15] [16] [17] [18] [19], not only due to their low volatility, but also to their highly tunable nature which allows for the design of specific ILs with remarkable affinity for CO 2 over other flue gases [20] [21] [22] [23] [24]. "
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    Journal of Membrane Science 06/2015; 483(1):155-165. DOI:10.1016/j.memsci.2015.02.020 · 4.91 Impact Factor
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    • "ILs are organic salts that consist entirely of weakly coordinating ions. An IL typically has a melting point below 100 C [16] [17] [18], a negligible vapor pressure [19], low flammability [20], high thermal stability [21], a large electrochemical window, and a broad liquidus range [22]. Therefore, substitution of volatile hydrocarbon-based organic solvents with ILs could lead to inherently safer and more environmentally friendly extraction processes [13]. "
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    ABSTRACT: The purpose of our study was to select the most effective ionic liquid (IL) extraction solvents for NdCl3 and DyCl3 using a theoretical conductor-like screening model for real solvents (COSMO-RS) based on quantum chemistry and the statistical thermodynamics of predefined NdCl3-IL and DyCl3-IL systems. The thermodynamics of the extraction process were predicted with the COSMO-RS method.NdCl3 and DyCl3 were considered in 4400 different ILs. As predicted, the chemical potential values of both NdCl3 and DyCl3 decreased significantly in systems with ILs based on the cation of dodecyl-dimethyl-3-sulfopropylammonium and the anions of bis(2,4,4-trimethylpentyl) phosphinate, decanoate, and benzoate.Considering the calculated physicochemical properties of the ILs containing these specific ions, the most effective IL extraction solvents for liquid–liquid extraction of the salts were selected. Experiments confirmed the high extraction efficiency of the ionic liquids chosen based on the COSMO-RS predictions.The COSMO-RS approach can be applied before extensive experimental tests to quickly screen the affinity of any rare earth element (REE) for a large number of IL systems, if only the physical dissolution of the REEs is considered.
    Fluid Phase Equilibria 12/2014; 383. DOI:10.1016/j.fluid.2014.10.018 · 2.24 Impact Factor
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    • "ILs are organic salts that consist entirely of weakly coordinating ions. An IL typically has a melting point below 100 C [16] [17] [18], a negligible vapor pressure [19], low flammability [20], high thermal stability [21], a large electrochemical window, and a broad liquidus range [22]. Therefore, substitution of volatile hydrocarbon-based organic solvents with ILs could lead to inherently safer and more environmentally friendly extraction processes [13]. "
    Fluid Phase Equilibria 10/2014; · 2.24 Impact Factor
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