Effect of temperature and composition on the density, viscosity surface tension and excess quantities of binary mixtures of 1-ethyl-3-methylimidazolium tricyanomethanide with thiophene

Abstract

Thermal properties of the ionic liquid (IL) 1-ethyl-3-methylimidazolium tricyanomethanide, ([EMIM][TCM]), measured by the Differential scanning calorimetry (DSC) as glass transition temperature (Tg,1), heat capacity change at glass transition temperature (ΔCp(g),1), melting temperature (Tfus), enthalpy of melting (ΔHfus), phase transition temperature (Ttr), enthalpy of phase transition (ΔtrH) and decomposition temperature (Td) were presented. The density and viscosity for the binary mixtures containing [EMIM][TCM] and thiophene at six temperatures (298.15, 308.15, 318.15, 328.15, 338.15 and 348.15K) and ambient pressure were reported. The density and viscosity as a function of temperature were tested by an empirical second-order polynomial and by the Vogel–Fucher–Tammann equation. The density and viscosity variations with compositions were described by polynomials. Excess molar volumes were described by the Redlich–Kister polynomial expansion. Viscosity deviations were calculated and correlated by the Redlich–Kister polynomial expansions. The surface tensions of pure ionic liquid and binary mixtures of [EMIM][TCM] and thiophene were measured at atmospheric pressure at five temperatures (298.15, 308.15, 318.15, 328.15, and 338.15K). The surface tension deviations were calculated and correlated by the Redlich–Kister polynomial expansion. The temperature dependence of interfacial tension was used to evaluate the excess surface energy, the surface enthalpy, the critical temperature, parachor and speed of sound for pure ionic liquid. These measurements have been provided to complete information of the influence of temperature on physico-chemical properties for the selected IL, which was chosen as a possible new entrainer in the separation of sulfur compounds from fuels. A qualitative analysis on these quantities in terms of molecular interactions is reported. The obtained results indicate that ionic liquid interactions with alcohols are strong dependent on the special trend of packing effects and hydrogen bonding of this ionic liquid with polar solvent.