Thermodynamic behaviour of ethanol+methanol+2-ethoxy-2-methylpropane system. Physical properties and phase equilibria

The densities, refractive indices and speeds of sound of ternary ethanol+methanol+2-ethoxy-2-methylpropane (ETBE) mixtures were determined at 298.15 K and atmospheric pressure, and were used to calculate the corresponding excess molar volumes and the deviations of the molar refractive index and isentropic compressibility from linear dependence on concentration. These excess and deviational quantities were best predicted by the equations of Radojkovic, Kohler and Jacob and Fitzner. Vapour–liquid equilibrium (VLE) data were obtained for the ternary system at 101.32 kPa, shown to pass thermodynamic consistency tests, correlated by means of the equations Wilson, NRTL and UNIQUAC, and compared with the results predicted by the ASOG-KT and original and modified UNIFAC methods and by the equations of Wilson, NRTL and UNIQUAC with interaction parameters obtained from data for the relevant binary systems. The agreement between the experimental data and the latter predictions was as good as was achieved by ASOG-KT and UNIFAC-Dortmund, which were the best of the group contribution methods.