VAPOR-LIQUID-EQUILIBRIA FOR THE SYSTEM WATER PLUS TERT-PENTANOL AT 4 TEMPERATURES

Precise isothermal vapor-liquid equilibrium data at 10, 30, 55 and 70 degrees C for the system water + tert.-pentanol were measured using a computer-operated differential static apparatus, Activity coefficients at infinite dilution were derived from the experimental P - x data in the dilute region using a flexible Legendre polynomial, and the vapor -liquid-liquid locus was derived directly from the P - x data near the liquid-liquid phase boundary, Heteroazeotropic points were measured d irectly by distillation using a rotating band column, Furthermore the UNIQUAC and the NRTL models were used to correlate the experimental P - x data and to derive the azeotropic data. Experimental H-E data were taken from literature and used together with the experimental P - x d ata to simultaneously fit temperature dependent interaction parameters for UNIQUAC and NRTL. The parameters were used to predict the azeotro pic composition over a large temperature range, The results were compa red with those of a simple analytical thermodynamic equation using onl y the pure component vapor pressure data, heats of mixing in the heter ogeneous region and the azeotropic composition at one temperature. Hea ts of mixing were measured at 140 degrees C with the help of a flow ca lorimeter in order to determine the slope of H-E VS. x(1) in the heter ogeneous region, The H-E data were used to check the reliability of th e G(E) model parameters and the equation to calculate the temperature dependence of the heteroazeotropic composition.