Volumetric behaviour of six ionic liquids from T=(278 to 398)K and up to 120MPa

In this paper the volumetric behaviour of the ionic liquids 1-butyl-1-methylpyrrolidinium tetracyanoborate,1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate, 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate, 1,3-dimethylimidazolium dimethylphosphate, 1-ethyl-3-methylimidazoliumhexylsulfate, and trihexyl(tetradecyl)phosphonium tris(pentafluoroethyl)trifluorophosphate is reported. Density was measured over the temperature range (278.15 to 398.15) K up to120 MPa by means of a high pressure densimeter based on the vibrating tube principle. Experimentalvalues were correlated as a function of temperature and pressure by means of the Tammann–Taitequation obtaining standard deviations lower than 3 x 10^-4 g cm^-3. From this correlation, isothermalcompressibility and isobaric thermal expansivity are obtained by differentiation. Furthermore, two groupcontribution methods proposed by Gardas and Coutinho and by Jacquemin et al. are applied to thesefluids to analyse their prediction abilities to determine densities, as well as an equation proposed byKiselev et al. to obtain isothermal compressibility at 0.1 MPa.