Surface Tensions and the Gibbs Excess Surface Concentration of Binary Mixtures of the Ionic Liquid 1-Ethyl-3-methylimidazolium Bis[(trifluoromethyl)sulfonyl]imide with Tetrahydrofuran and Acetonitrile

The surface tensions of binary mixtures containing the ionic liquid 1-ethyl-3-methyl-imidazolium bis[(trifluoromethyl-sulfonyl]imide ([EMIM][NTf(2)]) and the aprotic solvents tetahydrofuran (THF) or acetonitrile were measured at temperatures in the range from (293.15 to 313.15) K (or to 308.15 K for the system with THF) using the pendant drop method. On the basis of these experimental results and activity coefficients taken from vapor pressure measurements, the Gibbs excess surface concentrations for mixtures were calculated. The results and their relationship to electrolyte solutions are discussed.