Vapor pressure measurement and correlation of acetonitrile + 1-butyl-3-methylimidazolium chloride, + 1-butyl-3-methylimidazolium tetrafluoroborate, and + 1-hexyl-3-methylimidazolium chloride

Vapor pressures were measured for acetonitrile + 1-butyl-3-methylimidazolium chloride ([C4mim][Cl]), + 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) and + 1-hexyl-3-methylimidazolium chloride ([C6mim][Cl]) at temperatures of 313 to 353 K by a quasi-static method. The experimental data for the binary systems were correlated by the non-random two liquid (NRTL) equation with an average absolute relative deviation (AARD) of within 1.84%. The results indicate that the three ionic liquids (ILs) can result in a negative deviation from the Raoult's law for the binary solutions containing acetonitrile, and the affinity between ILs and acetonitrile molecules follows the order [C4mim][BF4] + acetonitrile > [C4mim][Cl] + acetonitrile > [C6mim][Cl] + acetonitrile.

Graphical AbstractFigure shows that for a given mole fraction of ILs, the order of the activity coefficients is [C6mim][Cl] > [C4mim][Cl] > [C4mim][BF4]. It indicates that the affinity between the IL and acetonitrile molecules follows the order [C4mim][BF4]-acetonitrile > [C4mim][Cl]-acetonitrile > [C6mim][Cl]-acetonitrile. The similar results could also be observed at the other temperatures.Figure optionsDownload full-size imageDownload as PowerPoint slide