Ternary Liquid-Phase Equilibria of an Azeotropic Mixture (Heptane + Isopropyl Alcohol) with Deep Eutectic Solvents

Abstract

The present study reports the result of the measurement and analysis of the solubility curve and tie-line data of four ternary systems containing heptane–isopropyl alcohol azeotrope mixtures and deep eutectic solvents (DESs) at T = 298.2 K and p = 0.1 MPa. This investigation is aimed to evaluate the efficiency of the prepared DESs as extractants in the separation of the heptane–alcohol azeotropic mixtures through liquid–liquid extraction (LLE) processes. In this study, four choline chloride-based DESs were prepared by a heating process. Two hydrogen bond donor (HBD) compounds (i.e., ethylene glycol and propylene glycol) were chosen in the preparation of the DESs. The solubility curves show that the effect of DESs on the immiscibility region is small. The studied systems display the type-1 LLE behavior. The measured tie-line values were adequately fitted through the nonrandom two-liquid (NRTL) thermodynamic model, and the interaction parameter values were determined. The correlation data appeared to be in good agreement with the measured tie-lie data. The extraction capacity (distribution constants and selectivities) of the studied DESs was determined. The DESs had high and similar selectivity values for the studied systems. Moreover, the distribution constants were larger than unity, indicating a favorable solvent-to-feed ratio.