Isobaric vapor-liquid equilibrium (VLE) data were measured for three ternary systems of tert-butanol (1) + water (2) + TRIS (3), 2-propanol (1) + water (2) + EPPS (3), and 1-propanol (1) + water (2) + EPPS (3) at 101.32 kPa by using a modified recirculating type of Othmer equilibrium still. The concentration range of the added biological buffer is from 0.05 to 0.30 in mass fraction. The presence of TRIS produced significantly azetropic composition shift for the aqueous tert-butanol system. In the presence of EPPS in aqueous 2-propanol mixture, the azeotropic composition shifting effect was also found substantially from aqueous 2-propanol system, while only minor effect on the VLE behavior for the aqueous 1-propanol system. The experimental VLE data were correlated with the NRTL model to determine the binary interaction parameters. Generally, the NRTL model correlate reasonably well for the systems investigated in this study. These new VLE ternary data of EPPS-containing systems were also taken as a basis for evaluating the applicability of the binary parameters determined from the liquid-liquid equilibrium (LLE) data for predicting the VLE properties. Large discrepancy was found from this evaluation, and indicating that the simulation of buffer-recovery distillation column should use the parameters determined from the VLE data.

Isobaric vapor-liquid equilibrium (VLE) data were measured for three ternary systems of tert-butanol (1) + water (2) + TRIS (3), 2-propanol (1) + water (2) + EPPS (3), and 1-propanol (1) + water (2) + EPPS (3) at 101.32 kPa by using a modified recirculating type of Othmer equilibrium still. The concentration range of the added biological buffer is from 0.05 to 0.30 in mass fraction. The presence of TRIS produced significantly azetropic composition shift for the aqueous tert-butanol system. In the presence of EPPS in aqueous 2-propanol mixture, the azeotropic composition shifting effect was also found substantially from aqueous 2-propanol system, while only minor effect on the VLE behavior for the aqueous 1-propanol system. The experimental VLE data were correlated with the NRTL model to determine the binary interaction parameters. Generally, the NRTL model correlate reasonably well for the systems investigated in this study. These new VLE ternary data of EPPS-containing systems were also taken as a basis for evaluating the applicability of the binary parameters determined from the liquid-liquid equilibrium (LLE) data for predicting the VLE properties. Large discrepancy was found from this evaluation, and indicating that the simulation of buffer-recovery distillation column should use the parameters determined from the VLE data.

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