Determination and correlation of solid–liquid phase equilibrium and phase diagram for multicomponent system of mixed dibasic acids. (I) Ternary system of adipic acid + glutaric acid + ethanol system

• The solid–liquid phase equilibrium of adipic acid + glutaric acid + ethanol system were measured under 101.3 kPa.
• The ternary phase diagrams were constructed at three temperatures.
• The ternary phase diagrams were correlated and calculated by Wilson and NRTL model.
• The densities of the equilibrium liquid phase were obtained and correlated with an empirical equation.

In this work, the solid–liquid phase equilibrium data for ternary system of adipic acid + glutaric acid + ethanol were measured using an isothermal saturation method at the three temperatures of 283.15, 303.15, and 313.15 K under 101.3 kPa. Three isothermal phase diagrams were built according to the measured solubility data. There were two pure solids formed in the ternary system at a given temperature, which corresponded to pure adipic acid and pure glutaric acid, and were confirmed by Schreinemaker's method of wet residue. The crystallization region of glutaric acid was smaller than that of adipic acid at each temperature. Two thermodynamic models, NRTL and Wilson were employed to correlate and calculate the mutual solubility data for the ternary adipic acid + glutaric acid + ethanol system. Results indicated that calculated results with NRTL model agreed well than those with Wilson model. Furthermore, the densities of the equilibrium liquid phase were obtained and correlated with an empirical equation.

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