Impact of the cation symmetry on the mutual solubilities between water and imidazolium-based ionic liquids
authors Martins, MAR; Neves, CMSS; Kurnia, KA; Luis, A; Santos, LMNBF; Freire, MG; Pinho, SP; Coutinho, JAP
nationality International
journal FLUID PHASE EQUILIBRIA
author keywords Mutual solubilities; Ionic liquids; Water; Cation symmetry; COSMO-RS
keywords COSMO-RS; BINARY-SYSTEMS; AQUEOUS-SOLUTION; UNIFAC MODEL; EXTRACTION; RECOVERY; SURFACE; TEMPERATURE; EQUILIBRIA; VOLATILITY
abstract Aiming at the evaluation of the impact of the ionic liquids (ILs) cation symmetry on their phase behaviour, in this work, novel mutual solubilities with water of the symmetric series of [C(n)C(n)im][NTf2] (with n=1-5) were determined and compared with their isomeric forms of the asymmetric [C(n)C(1)im][NTf2] group. While the solubility of isomeric ILs in water was found to be similar, the solubility of water in ILs follows the same trend up to a maximum cation alkyl side chain length. For n >= 4 in [C(n)C(n)im][NTf2] the solubility of water in the asymmetric ILs is slightly higher than that observed in the symmetric counterparts. The thermodynamic properties of solution and solvation derived from the experimental solubility data of ILs in water at infinite dilution, namely the Gibbs energy, enthalpy and entropy were used to evaluate the cation symmetry effect on the ILs solvation. It is shown that the solubility of ILs in water is entropically driven and highly influenced by the cation size. Accordingly, it was found that the ILs solubility in water of both symmetric and asymmetric series depends on their molecular volume. Based on these findings, a linear correlation between the logarithm of the solubility of ILs in water and their molar volume is here proposed for the [NTf2]-based ILs at a fixed temperature. (C) 2014 Elsevier B.V. All rights reserved.
publisher ELSEVIER SCIENCE BV
issn 0378-3812
year published 2014
volume 375
beginning page 161
ending page 167
digital object identifier (doi) 10.1016/j.fluid.2014.05.013
web of science category Thermodynamics; Chemistry, Physical; Engineering, Chemical
subject category Thermodynamics; Chemistry; Engineering
unique article identifier WOS:000339533200019
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journal impact factor (jcr 2016): 2.473
5 year journal impact factor (jcr 2016): 2.499
category normalized journal impact factor percentile (jcr 2016): 64.949
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