Effect of temperature and composition on the surface tension and thermodynamic properties of binary mixtures of 1-butyl-3-methylimidazolium thiocyanate with alcohols.

The surface tensions of pure ionic liquid, 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]), and binary mixtures of [BMIM][SCN] with alcohols (1-butanol, 1-pentanol, 1-hexanol) have been measured at atmospheric pressure at five temperatures in the range from 298.15 to 328.15 K. These measurements have been provided to complete information of the influence of temperature on surface tension for the selected ionic liquid, which was chosen as a possible new entrainer in extraction processes. The surface thermodynamic functions such as surface entropy and enthalpy have been derived from the temperature dependence of the surface tension values, as well as the critical temperature, parachor, and speed of sound for pure ionic liquid. The investigations include the effect of the alkyl chain length of an alcohol and polarity of a solvent on the surface tension.