Experimental and Modeling of Vapor–Liquid Equilibria for Electrolyte Solution Systems

Abstract

Vapor−liquid equilibrium (VLE) data are reported for binary and mixed electrolyte solutions containing CaCl 2 , MgCl 2 , K 2 SO 4 , MgSO 4 , and KCl at total molality of salt between (0.0 and 12.0) mol•kg −1 . The measurements were carried out with a pressure between (6.3 and 101.3) kPa in a computer-controlled glass apparatus. An activity coefficient model based on the hypothesis of hydration was deduced in this paper. Experimental data and literature data for 20 salts, with temperature spanning from (273.15 to 415.85) K, were successfully correlated using the developed model. Meanwhile, the model was also successfully applied to predict the VLE data in mixed electrolyte solution systems with the binary parameters.

Thermodynamic modeling of aqueous Na+–K+–Mg2+–SO42− quaternary system

“…Fig. 1 shows a comparison of the model results for vapor pressure with the literature data of Xu et al [27] at temperatures from 310 to 376 K. The model correlates these data well with a MRD value of only 0.26%. In fact, the model correlates all available vapor pressure data [28][29][30][31] very well, as shown in Table 4, with MRD values less than or around 1%.…”

“…d Solubility data alone not sufficient to accurately determine the value. Extensive thermodynamic data of aqueous MgSO 4 solution are available in the literature [9,[26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. Table 3 shows readily accessible thermodynamic data including vapor pressure, enthalpy, heat capacity, mean ionic activity coefficient, osmotic coefficient and salt solubility that are used in regression and validation of the thermodynamic model for aqueous MgSO 4 solution.…”

“…Vapor Pressure of aqueous MgSO 4 solution: comparison of experimental data[27] in symbols with model results in solid lines:…”

Thermodynamic modeling of aqueous Na + –K + –Cl − –SO 4 2− quaternary system with electrolyte NRTL model

“…Table 3 shows the MRD values for the comparisons. It is noteworthy that the MRD value for the recent data of Xu et al [32] is as high as 3.2% while the MRD values from other data sources are less than 1%. Fig.…”

“…Heat capacity, C p , and liquid enthalpy, H l , of the liquid solution are calculated with the following equations: (20) Extensive thermodynamic data such as vapor pressure depression, molality scale mean ionic activity coefficient, osmotic coefficient, excess enthalpy, heat capacity, and salt solubility for aqueous K 2 SO 4 binary are available [28][29][30][31][32][33][34][35][36][37][38][39][40][41]. Table 3 shows some readily available literature data used in this study and their ranges of temperature and concentration.…”