Mutual Solubilities of Water and the [Cnmim][Tf2N] Hydrophobic Ionic Liquids

M.G. Freire, P.J. Carvalho, Ramesh Gardas, I.M. Marrucho, L.M.N.B.F. Santos, J.A.P. Coutinho

Research output: Contribution to journalArticle

245 Citations (Scopus)

Abstract

Ionic liquids (ILs) have recently garnered increased attention because of their potential environmental benefits as "green" replacements over conventional volatile organic solvents. While ILs cannot significantly volatilize and contribute to air pollution, even the most hydrophobic ones present some miscibility with water posing environmental risks to the aquatic ecosystems. Thus, the knowledge of ILs toxicity and their water solubility must be assessed before an accurate judgment of their environmental benefits and prior to their industrial applications. In this work, the mutual solubilities for [C2-C8mim][Tf2N] (n-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) and water between 288.15 and 318.15 K at atmospheric pressure were measured. Although these are among the most hydrophobic ionic liquids known, the solubility of water in these compounds is surprisingly large, ranging from 0.17 to 0.36 in mole fraction, while the solubility of these ILs in water is much lower ranging from 3.2 × 10-5 to 1.1 × 10-3 in mole fraction, in the temperature and pressure conditions studied. From the experimental data, the molar thermodynamic functions of solution and solvation such as Gibbs energy, enthalpy, and entropy at infinite dilution were estimated, showing that the solubility of these ILs in water is entropically driven. The predictive capability of COSMO-RS, a model based on unimolecular quantum chemistry calculations, was evaluated for the description of the binary systems investigated providing an acceptable agreement between the model predictions and the experimental data both with the temperature dependence and with the ILs structural variations.
Original languageEnglish
Pages (from-to)1604-1610
Number of pages7
JournalJournal of Physical Chemistry B
Volume112 (6)
Issue number6
DOIs
Publication statusPublished - 14 Feb 2008

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Ionic Liquids
Ionic liquids
solubility
Solubility
Water
liquids
water
Imides
Quantum chemistry
air pollution
Aquatic ecosystems
imides
Solvation
quantum chemistry
ecosystems
Gibbs free energy
Air pollution
toxicity
Organic solvents
Dilution

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Freire, M. G., Carvalho, P. J., Gardas, R., Marrucho, I. M., Santos, L. M. N. B. F., & Coutinho, J. A. P. (2008). Mutual Solubilities of Water and the [Cnmim][Tf2N] Hydrophobic Ionic Liquids. Journal of Physical Chemistry B, 112 (6)(6), 1604-1610. https://doi.org/10.1021/jp7097203
Freire, M.G. ; Carvalho, P.J. ; Gardas, Ramesh ; Marrucho, I.M. ; Santos, L.M.N.B.F. ; Coutinho, J.A.P. / Mutual Solubilities of Water and the [Cnmim][Tf2N] Hydrophobic Ionic Liquids. In: Journal of Physical Chemistry B. 2008 ; Vol. 112 (6), No. 6. pp. 1604-1610.
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Freire, MG, Carvalho, PJ, Gardas, R, Marrucho, IM, Santos, LMNBF & Coutinho, JAP 2008, 'Mutual Solubilities of Water and the [Cnmim][Tf2N] Hydrophobic Ionic Liquids', Journal of Physical Chemistry B, vol. 112 (6), no. 6, pp. 1604-1610. https://doi.org/10.1021/jp7097203

Mutual Solubilities of Water and the [Cnmim][Tf2N] Hydrophobic Ionic Liquids. / Freire, M.G.; Carvalho, P.J.; Gardas, Ramesh; Marrucho, I.M.; Santos, L.M.N.B.F.; Coutinho, J.A.P.

In: Journal of Physical Chemistry B, Vol. 112 (6), No. 6, 14.02.2008, p. 1604-1610.

Research output: Contribution to journalArticle

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AU - Freire, M.G.

AU - Carvalho, P.J.

AU - Gardas, Ramesh

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AU - Santos, L.M.N.B.F.

AU - Coutinho, J.A.P.

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N2 - Ionic liquids (ILs) have recently garnered increased attention because of their potential environmental benefits as "green" replacements over conventional volatile organic solvents. While ILs cannot significantly volatilize and contribute to air pollution, even the most hydrophobic ones present some miscibility with water posing environmental risks to the aquatic ecosystems. Thus, the knowledge of ILs toxicity and their water solubility must be assessed before an accurate judgment of their environmental benefits and prior to their industrial applications. In this work, the mutual solubilities for [C2-C8mim][Tf2N] (n-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) and water between 288.15 and 318.15 K at atmospheric pressure were measured. Although these are among the most hydrophobic ionic liquids known, the solubility of water in these compounds is surprisingly large, ranging from 0.17 to 0.36 in mole fraction, while the solubility of these ILs in water is much lower ranging from 3.2 × 10-5 to 1.1 × 10-3 in mole fraction, in the temperature and pressure conditions studied. From the experimental data, the molar thermodynamic functions of solution and solvation such as Gibbs energy, enthalpy, and entropy at infinite dilution were estimated, showing that the solubility of these ILs in water is entropically driven. The predictive capability of COSMO-RS, a model based on unimolecular quantum chemistry calculations, was evaluated for the description of the binary systems investigated providing an acceptable agreement between the model predictions and the experimental data both with the temperature dependence and with the ILs structural variations.

AB - Ionic liquids (ILs) have recently garnered increased attention because of their potential environmental benefits as "green" replacements over conventional volatile organic solvents. While ILs cannot significantly volatilize and contribute to air pollution, even the most hydrophobic ones present some miscibility with water posing environmental risks to the aquatic ecosystems. Thus, the knowledge of ILs toxicity and their water solubility must be assessed before an accurate judgment of their environmental benefits and prior to their industrial applications. In this work, the mutual solubilities for [C2-C8mim][Tf2N] (n-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) and water between 288.15 and 318.15 K at atmospheric pressure were measured. Although these are among the most hydrophobic ionic liquids known, the solubility of water in these compounds is surprisingly large, ranging from 0.17 to 0.36 in mole fraction, while the solubility of these ILs in water is much lower ranging from 3.2 × 10-5 to 1.1 × 10-3 in mole fraction, in the temperature and pressure conditions studied. From the experimental data, the molar thermodynamic functions of solution and solvation such as Gibbs energy, enthalpy, and entropy at infinite dilution were estimated, showing that the solubility of these ILs in water is entropically driven. The predictive capability of COSMO-RS, a model based on unimolecular quantum chemistry calculations, was evaluated for the description of the binary systems investigated providing an acceptable agreement between the model predictions and the experimental data both with the temperature dependence and with the ILs structural variations.

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Freire MG, Carvalho PJ, Gardas R, Marrucho IM, Santos LMNBF, Coutinho JAP. Mutual Solubilities of Water and the [Cnmim][Tf2N] Hydrophobic Ionic Liquids. Journal of Physical Chemistry B. 2008 Feb 14;112 (6)(6):1604-1610. https://doi.org/10.1021/jp7097203