Phase Equilibria of Ternary Liquid–Liquid Systems (Water + C1–C4 Monocarboxylic Acids + Dibutyl Ether) at Three Different Temperatures: Modeling with A-UNIFAC

Abstract

Liquid–liquid equilibrium (LLE) data for the ternary systems composed of water, C1–C4 monocarboxylic acids, and dibutyl ether were determined at three different temperatures (293.15, 303.15, and 313.15 K) and atmospheric pressure. The experimental solubility curves and mutual solubilities of (water + dibutyl ether) were determined by the cloud-point method, whereas the tie-lines of conjugate phases were obtained via GC analysis. The examined C1–C4 monocarboxylic acids are valuable components for estimating the effect of acid structure on LLE. The separation factor calculated from experimental LLE data is indicative of the ability of the solvent to effectively recover the acid. Equilibrium distribution of C1–C4 acids is better for more structured propionic and butyric acids as compared to less structured formic and acetic acids, and the general ranking with respect to the separation factor (S) follows the order: C4 > C3 > C2 > C1, and T293.15 < T303.15 ≤ T313.15. The LLE data were predicted with the group-contribution method A-UNIFAC with the newly estimated parameters, which shows an appropriate consistency with the experimental data.