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Phase Equilibria and Modeling of Pyridinium-Based Ionic Liquid Solutions

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journal contribution
posted on 25.11.2010, 00:00 by Urszula Domańska, Marek Królikowski, Deresh Ramjugernath, Trevor M. Letcher, Kaniki Tumba
The phase diagrams of the ionic liquid (IL) N-butyl-4-methylpyridinium bis{(trifluoromethyl)sulfonyl}imide ([BM4Py][NTf2]) with water, an alcohol (1-butanol, 1-hexanol, 1-octanol, 1-decanol), an aromatic hydrocarbon (benzene, toluene, ethylbenzene, n-propylbenzene), an alkane (n-hexane, n-heptane, n-octane), or cyclohexane have been measured at atmospheric pressure using a dynamic method. This work includes the characterization of the synthesized compound by water content and also by differential scanning calorimetry. Phase diagrams for the binary systems of [BM4Py][NTf2] with all solvents reveal eutectic systems with regards to (solid−liquid) phase equilibria and show immiscibility in the liquid phase region with an upper critical solution temperature (UCST) in most of the mixtures. The phase equilibria (solid, or liquid−liquid) for the binary systems containing aliphatic hydrocarbons reported here exhibit the lowest solubility and the highest immiscibility gap, a trend which has been observed for all ILs. The reduction of experimental data has been carried out using the nonrandom two-liquid (NRTL) correlation equation. The phase diagrams reported here have been compared with analogous phase diagrams reported previously for systems containing the IL N-butyl-4-methylpyridinium tosylate and other pyridinium-based ILs. The influence of the anion of the IL on the phase behavior has been discussed.