Volumetric properties of three pyridinium-based ionic liquids with a common cation or anion

Abstract New density data at high pressure for 1-butylpyridinium bis(trifluoromethyl-sulfonyl)imide, 1-hexylpyridinium bis(trifluoromethylsulfonyl)imide and 1-hexylpyridinium tetrafluoroborate have been obtained in a broad range of temperatures (283.15–338.15) K, and pressures (0.1–65) MPa using a high temperature, high pressure vibrating tube densimeter. For 1-butylpyridinium bis(trifluoromethylsulfonyl)-imide the measurement temperatures were from 303.15 to 338.15 K, due to its melting temperature. The raw densities have been corrected taking into account viscosity. The corrected densities have been satisfactorily correlated with temperature and pressure using the Tait equation. Moreover, some thermodynamic derived properties such as isobaric expansibility, isothermal compressibility and internal pressure were also obtained and discussed. In addition, the group contribution method proposed by Paduszynski and Domanska has been used to calculate the densities of the ionic liquids; a good concordance between experiment and predicted results is found.