Phase equilibria study of (ionic liquid + water) binary mixtures

The (solid + liquid) and (liquid + liquid) phase equilibria for 10 (ionic liquid + water) binary mixtures have been determined by a dynamic method at a wide temperature range at atmospheric pressure.The mutual immiscibility with an upper critical solution temperature (UCST) for the binary systems {4-(2-methoxyethyl)-4-methylmorpholinium trifluorotris(perfluoroethyl)phosphate, or 4-(2-methoxyethyl)-4-methylmorpholinium bis(trifluoromethylsulfonyl)imide, or 1-(2-methoxyethyl)-1-methylpiperidinium trifluorotris(perfluoroethyl)phosphate, or 1-(2-methoxy-ethyl)-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide, or 1-(2-methoxyethyl)-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, or 4-(2-methoxyethyl)-4-methylpyrrolidinium trifluorotris(perfluoroethyl)phosphate (1) + water (2)} were detected. Complete miscibility in the liquid phase, over the whole range of ionic liquid mole fraction, was observed for the binary mixtures containing: 1-butyl-1-methylpiperidinium dicyanamide, or 1-butyl-1-methylpyrrolidinium dicyanamide, or 1-butyl-4-methylpyridinium dicyanamide, or 1-butyl-4-methylpyridinium thiocyanate.For the tested binary systems with immiscibility gap the parameters of the LLE correlation have been derived using the NRTL equation. The (solid + liquid) phase equilibria have been correlated by means of NRTL, UNIQUAC and Wilson equations and compared to the literature data for different ionic liquids. The influence of the ionic liquid structure on water solubility was discussed.