Viscosity of ionic liquid mixtures of 1-alkyl-3-methylimidazolium hexafluorophosphate + CO2

The viscosities of the mixtures 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM][PF6]) + CO2 and 1-octyl-3-methylimidazolium hexafluorophosphate ([OMIM][PF6]) + CO2 were measured with a rolling ball viscometer. The CO2 mole fraction for one mixture ranged up to 0.434 and the other up to 0.447. The viscosities were measured at 293.15–353.15 K and 10–20.0 MPa. The experimental uncertainty in viscosity was estimated to be within ±3.0%. The experimental data were compared with McAllister's three-body model, which correlated with the experimental data within average absolute deviations of 5.9%.

► Viscosity measurement of [HMIM][PF6] + CO2 mixture.
► Viscosity measurement of [OMIM][PF6] + CO2 mixture.
► The viscosity of the mixtures dramatically decreased with an increase in the CO2 mole fraction.
► The experimental data were correlated with McAllister's three-body model within an AAD of 5.9%.