Journal of Chemical and Engineering Data, Vol.52, No.1, 199-205, 2007
Isobaric vapor-liquid equilibria for water plus 2-propanol plus 1-butyl-3-methylimidazolium tetrafluoroborate
An ebulliometer has been designed for vapor-liquid equilibrium measurement of systems containing an ionic liquid (IL). The new design allows vapor phase sampling and analysis, while the liquid composition is calculated on the basis of synthetic quantities and with regard to vapor phase composition, quantity of vapor material, and vapor-to-liquid circulation ratio. T, x, y data are reported for the system water + 2-propanol + 1-butyl-3-methylimidazolium tetrafluoroborate at 100 kPa and ionic liquid mass fractions of 0.300, 0.500, and 0.700. The quasi-binary system water + 2-propanol presents a temperature minimum when IL mass fraction is kept constant at these three concentrations. Addition of the IL with mass fraction of 0.500 and 0.700 breaks the azeotrope. Activity coefficients are calculated from the experimental data for the volatile components in the IL-containing mixture. The activity coefficients are directly related to the relative volatility of the quasi-binary mixture and show rather complicated composition dependence.