Vapor pressures and activity coefficients of binary mixtures of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide with acetonitrile and tetrahydrofuran

A new apparatus for the determination of VLE has been constructed which works for absolute pressure measurements as well as for measuring differential pressures. The first results obtained are (vapor + liquid) equilibria (VLE) of binary mixtures containing acetonitrile or tetrahydrofuran and the ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [EMIm][NTf2] by using the absolute pressures method. VLE measurements were carried out over the whole concentration range at four different temperatures between 293.15 K and 313.15 K. Activity coefficients (γ1) of the solvents in [EMIm][NTf2] and their osmotic coefficients (ϕ1) have been determined from the VLE data.

► A new apparatus for the determination of VLE is presented.
► The first vapor pressures for binary mixtures containing aprotic solvents in IL are reported.
► Calculated activity coefficients and osmotic coefficients reveal a strong non-ideal behavior.
► A more detailed study of the highly diluted IL concentration range is necessary to test the Debye–Hückel law.