(Solid + liquid) and (liquid + liquid) phase equilibria of (IL + water) binary systems. The influence of the ionic liquid structure on mutual solubility

Abstract

In this work binary (solid+liquid) and (liquid+liquid) phase equilibria measurements for the new ionic liquids: 1-ethyl-3-methylimidazolium tricyanomethanide, [EMIM][TCM], 1-butyl-3-methylimidazolium tricyanomethanide, [BMIM][TCM], 1-butyl-1-methyl-pyrrolidinium tricyanomethanide, [BMPYR][TCM], 1-butyl-1-methylmorpholinium tricyanomethanide, [BMMOR][TCM], trihexyltertadecylphosphonium tricyanomethanide, [P6,6,6,14][TCM] with water over a wide temperature range and at atmospheric pressure have been determined using dynamic method. In order to discuss the influence of the ionic liquid structure on mutual miscibility with water the phase equilibria for 1-butyl-1-methyl-pyrrolidinium trifluoromethanesulfonate, [BMPYR][CF3SO3], 1-butyl-1-methylpyrrolidinium tetracyanoborate, [BMPYR][TCB] and 1-butyl-3-methylimidazolium dicyanamide, [BMIM] [DCA] were detected. For the tested binary systems with immiscibility gap the parameters of the LLE correlation have been derived using the NRTL equation. For the binary mixtures of water and [EMIM][TCM], [BMIM][DCA] and [BMPYR][CF3SO3] the complete miscibility in the liquid phase over whole composition range was observed. For these systems the (solid+liquid) phase equilibria have been correlated by means of NRTL, UNIQUAC and Wilson equations. The influence of the ionic liquid structure on water solubility was discussed. Additionally the basic thermal characterization of pure ionic liquids that is: the glass transition temperature, the change of heat capacity at the glass-transition temperature, temperature and enthalpy of phase transition and temperature and enthalpy of melting were determined using DSC technique. Decomposition temperature was detected by thermograwimetry.