Liquid–Liquid Equilibrium Study for a Ternary System of Water + 1,2-Pentanediol + Organic Solvent

The efficient extraction of bioderived 1,2-pentanediol from dilute aqueous solutions is important for its use in industrial production. Three organic solvents, ethyl acetate, methyl isobutyl ketone (MIBK), and 2-heptanol, were studied for their liquid–liquid equilibria in 1,2-pentanediol extraction at 101 kPa and two temperatures (283.2 and 293.2 K). Experimental results indicated that 2-heptanol and methyl isobutyl ketone exhibited high extraction capability and selectivity toward 1,2-pentanediol. The consistency of the phase equilibrium data was verified using the Tobias–Othmer equation and the Hand equation. The experimental data were also correlated with the NRTL and UNIQUAC models, and the binary interaction parameters were regressed. Both NRTL and UNIQUAC models showed good agreement with the experimental data. Density functional theory calculations were performed to visualize and quantify the interaction between 1,2-pentanediol and the extractants. It is found that extractants with high selectivity also showed strong hydrogen bond strength.