(Liquid + liquid) equilibria of the (water + carboxylic acid + dibasic esters mixture (DBE-2)) ternary systems

• (Liquid + liquid) equilibria of water, carboxylic acid and dibasic esters mixture.
• UNIFAC and modified UNIFAC models were applied.
• Root mean square deviation was applied between experimental and theoretical data.
• Selectivity for separation of carboxylic acids/DBE-2 varies between 1.67 and 21.94.

(Liquid + liquid) equilibrium (LLE) data for the {water + carboxylic acid + dibasic esters mixture (dimethyl adipate + dimethyl glutarate)} system were determined experimentally at T = 298.2 K for each acid. In this work, we studied formic acid, acetic acid and propionic acid. All the phase diagrams were obtained by determining solubility curve and tie-line data. The reliability of the experimental tie-line data was confirmed by using the Othmer–Tobias correlation. The UNIFAC and modified UNIFAC models were used to predict the phase equilibrium in the system determined from experimental data using the interaction parameters between CH2, CH3, HCOOH, COOH, CH3COO, and H2O functional groups. Distribution coefficients and separation factors were evaluated for the immiscibility region.