Determination and Correlation of Solid-Liquid Phase Equilibrium and Phase Diagram for a Multicomponent System of Mixed Dibasic Acids. Ternary System of Succinic Acid plus Adipic Acid plus Ethanol

The solid liquid phase equilibrium for the ternary succinic acid + adipic acid + ethanol system was determined at 283.15, 303.15, and 313.15 K, respectively, under about 101.3 kPa. The mutual solubility for the ternary system were obtained. At each temperature, there existed two pure solid phases in the ternary system, which were pure succinic acid and pure adipic add, and identified by the Schreinemaker's wet residue method and X-ray diffraction (XRD) pattern. The crystallization region of adipic acid was a little smaller than that of succinic acid at a certain temperature. The solid-liquid phase equilibrium for the ternary system was correlated and calculated by using the Wilson and NRTL models, and the corresponding binary interaction parameters were acquired. Results showed that calculated solubility values with NRTL model agreed better than those with the Wilson model. In addition, the densities of the equilibrium liquor were obtained and correlated with an empirical equation. The mutual solubility and the phase diagram for the ternary system are helpful in separating Of succinic acid and adipic acid mixtures.