Phase equilibria for the systems containing electrolytes and alcohols

Abstract

Vapor-liquid equilibrium data of the water + 1,3-propanediol and water + 1,3-propanediol + lithium bromide systems were measured at atmospheric pressure. The apparatus used in this study is a circulation-type still, in which the vapor condensate is recirculated into the liquid phase. For the analysis of salt-containing solution, a method of refractometry and gravimetry was used. From the experimental measurements, the effect of lithium bromide on the VLE behavior of water + 1,3-propanediol was investigated. Low-pressure vapor-liquid equilibria for the water +1,3-propanediol system were measured at pressures of 60, 160, and 300 torr. The apparatus used in this work is a modified still especially designed for the measurement of low-pressure VLE, in which both liquid and vapor are continuously recirculated. All the experimental VLE data of the salt-free system were compared each other in order to examine the trend of relative volatility according to the change of system pressures. Low-pressure vapor-liquid equilibria for the water +1,3-propanediol + lithium bromide system were measured at pressures of 160 and 300 torr. Then, the salt effect investigated in the atmospheric VLE was also studied in the low-pressure VLE. The experimental data of the salt-free system were successfully correlated using Wilson, NRTL, and the UNIQUAC models. In addition, the extended UNIQUAC model of Sander et al. was applied to the calculation of the VLE for the salt-containing system. The effective description of the electrolyte VLE was possible at atmospheric pressure while a good accuracy of calculation results could not be obtained at low pressures. High-pressure vapor-liquid equilibria for the binary carbon dioxide + 3-methyl-1-butanol and carbon dioxide + 3-methyl-2-butanol systems were measured at 313.2K. The phase equilibrium apparatus used in this work is of the circulation type, in which the coexisting phases are recirculated, on-line sampled and analyzed. The critical pressu...