Vapor–Liquid Phase Equilibrium for Separation of Isopropanol from Its Aqueous Solution by Choline Chloride-Based Deep Eutectic Solvent Selected by COSMO-SAC Model

Abstract

To separate isopropanol from its aqueous solution by distillation, the deep eutectic solvents (DESs) with choline chloride, which were screened using the COSMO-SAC mode, were applied to eliminate the azeotropic point. The charge density distribution over the molecular surface was calculated for isopropanol, water, and DESs to analyze the interactions between different species. Based on the screening results, a DES consisting of choline chloride and triethylene glycol in a molar ratio of 1:3 was selected. To validate the selected DES for the separation of isopropanol from its aqueous solution, the isobaric vapor–liquid equilibrium (VLE) data for the system of isopropanol + water + DES were measured at a pressure of 101.3 kPa. According to the measured VLE data, the azeotropic point of isopropanol and water can be eliminated by the DES at a concentration of 10 wt %. Meanwhile, the thermodynamic consistency of the VLE data was checked by the van Ness test. The non-random two-liquid model was employed to correlate the VLE data, which were in agreement with the measured VLE data.

Thermodynamic and Transport Properties Modeling of Deep Eutectic Solvents: A Review on gE-Models, Equations of State, and Molecular Dynamics

“…This group followed the same modeling approach for other systems composed of DES + water + allyl alcohol . In both cases the DESs were considered as a pseudocomponent (pseudoternary approach). , …”

“…21 γ−φ Concept. One of the first to employ this modeling approach without the use of an equation of state, that is, assuming the fugacity coefficient equal to unity was Jiang et al 90 They evaluated the ChCl-based DESs used as azeotrope breakers for the isopropyl alcohol + water VLE. A COSMO-RS implementation was applied for solvent screening in order to select the best possible DES based on infinite dilution activity coefficients.…”

“…91 In both cases the DESs were considered as a pseudocomponent (pseudoternary approach). 90,91 In contrast, Zhang et al 92 applied the individual constituent approach. They evaluated the water + 2-propanol system at different DES (ChCl+glycerol) concentrations and fitted an NRTL model to the experimental data.…”

Isobaric Vapor–Liquid Equilibrium Data for the Isopropanol–Water System

“…Isopropanol–water separation started to raise interest early in the last century and has been then studied in recent years to develop efficient methods to obtain pure isopropanol. Several processes have been suggested such as azeotropic distillation, , pressure swing distillation, a single unit of pervaporation membrane or multistage arrangements for the dehydration of isopropanol under adiabatic and ideal isothermal conditions, liquid–liquid extraction, reactive distillation, adsorption, the adoption of ionic liquids for breaking the azeotrope, and extractive distillation through deep eutectic solvents, also known as low transition temperature mixtures (LTTMs). − …”

Isobaric Vapor–Liquid Equilibrium Data for Four Binary Systems of n-Hexane + 1,2-Dichloroethane, tert-Butyl Acetate, sec-Butyl Acetate, and n-Propyl Acetate at 101.3 kPa

“…Extractive distillation (ED) has emerged as a successful technology for the separation of close boiling/azeotropic mixtures. − The key of ED is to choose an appropriate and effective entrainer, which will directly affect energy consumption, economic benefits, and product quality. , By analyzing the azeotrope to be separated, the polarity of 1,2-dichloroethane is greater than that of n -hexane because of the presence of chlorine atoms in 1,2-dichloroethane. Therefore, choosing a solvent with high polarity is beneficial to the separation of the azeotrope.…”