Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

ABSTRACT

Ionic liquids (ILs) are an important new media and one of the most attractive solvents used in extraction and separation processes. This work presents some important physico-chemical properties and topics related to ILs, which were found by us as good extractive solvents for the desulfurization of fuels and for the separation of water/biobutan-1-ol. It consists of the most important series of experimental measurements of density and viscosity of pure ILs and in binary systems with thiophene and butan-1-ol: (N-hydroxyethylpyridinium tricyanomethanide, [C2OHPy][TCM] + thiophene), or (N-hydroxypropylpyridinium tricyanomethanide, [C3OHPy][TCM] + thiophene) or (N-benzyl-N-dodecyl-N,Ndimethylammonium bis(trifluoromethyl-sulfonyl)imide, [N1,1,12,Bz][NTf2] + butan-1-ol). These systems exhibit mainly negative molar excess volumes, V^E in systems with thiophene and slightly positive and negative in the system with butan-1-ol. The Redlich Kister equation was used for correlation of the liquid density, excess molar volumes and dynamic viscosity deviations as a function of temperature and composition, whereas Vogel-Fulcher-Tammann, VFT was used for describing the temperature dependence of dynamic viscosities. Very often, the high pressure is proposed for new technologies of separation and that is why we present the influence of pressure on the density of [C2OHPy][TCM], [C3OHPy][TCM] and [N1,1,12,Bz][NTf2] in a wide range of temperature from T = (298.15 to 348.15) K and pressure from p = (0.1 to 40) MPa. The Tait equation was used for the correlation of density as a function of mole fraction, temperature, and pressure. The influence of pressure for ILs, is as usual, not significant. The thermal expansion coefficient and isothermal compressibility coefficient as a function of temperature T, and pressure p are presented. Herein, surface tension of new ILs was measured for the collection of physico-chemical properties of the ILs used in this work. Also, the octan-1-ol/water, K_ow partition coefficients in ternary liquid-liquid phase equilibrium were determined for the systems {[C2OHPy][TCM], or [C3OHPy][TCM](1) + octan-1-ol (2) + water (3)} at temperature T = 298.15 K and the discussion of the biocompatibility of the used ILs is presented.