Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

Pressure volume temperature (PVT) measurements of ionic liquids ([bmim+][PF6-], [bmim+][BF4-], [bmim+][OcSO4-]) and analysis with the Sanchez Lacombe equation of state

Machida, H.[Hiroshi], Sato, Y.[Yoshiyuki], Smith, R. L.[Richard L.]
Fluid Phase Equilib. 2008, 264, 1-2, 147-155
ABSTRACT
Pressure volume temperature measurements of the pure ionic liquids 1-butyl-3-methyl-imidazolium hexafluorophosphate ([bmim+][PF6-]), 1- butyl-3-methyl-imidazolium tetrafluoroborate ([bmim+][BF4-]), 1-butyl-3-methyl-imidazolium octylsulfate ([bmim+][OcSO4-]) were performed with a metal bellows apparatus at temperatures from 313 to 473K and at pressures up to 200MPa. The pressure volume temperature data were used to determine parameters of the Sanchez Lacombe equation of state, which was used to calculate the hard core volume and free volume of ionic liquids. It was found that the hard core volume of the ionic liquid was related with anion size and was slightly smaller than the van derWaals volume estimated with Bondi methods. The free volumes of [bmim+][PF6-] and [bmim+][BF4-] calculated with the Sanchez Lacombe equation of state showed a similar pressure dependence and were close to each other (ca. 10 14 cm3/mol) whereas the values for [bmim+][OcSO4-] were much higher (ca. 18 25 cm3/mol) over the range of pressure.
Compounds
# Formula Name
1 C8H15F6N2P 1-butyl-3-methylimidazolium hexafluorophosphate
2 C8H15BF4N2 1-butyl-3-methylimidazolium tetrafluoroborate
3 C16H32N2O4S 1-butyl-3-methylimidazolium octyl sulfate
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 1
  • Mass density, kg/m3 ; Liquid
  • Pressure, kPa; Liquid
  • Temperature, K; Liquid
  • Liquid
  • Bellows volumetry
  • 181
  • POMD
  • 2
  • Mass density, kg/m3 ; Liquid
  • Pressure, kPa; Liquid
  • Temperature, K; Liquid
  • Liquid
  • Bellows volumetry
  • 181
  • POMD
  • 3
  • Mass density, kg/m3 ; Liquid
  • Pressure, kPa; Liquid
  • Temperature, K; Liquid
  • Liquid
  • Bellows volumetry
  • 170