Design Optimization of Deep Eutectic Solvent Composition and Separation Performance of Cyclohexane and Benzene Mixtures with Extractive Distillation

Abstract

Deep eutectic solvents (DESs) have properties that make them suitable candidates to be used as entrainers for extractive distillation. In the previous work, it was proven that DES(1:2) (tetrabutylammonium bromide: levulinic acid, 1:2, molar ratio) can break the cyclohexane-benzene azeotrope. In the present work, the HBA and HBD ratio and molar concentration of DES were optimized to obtain a better constitute and condition of DES to be utilized in cyclohexane and benzene extractive distillation. The physical properties and structure of the prepared DESs were characterized. Vapor–liquid equilibrium data of the ternary system (benzene + cyclohexane + DESs) were also measured at atmospheric pressure. All experimental equilibrium data were correlated with Wilson, nonrandom two-liquid (NRTL), and universal quasichemical (UNIQUAC) activity coefficient models, from which the coefficient of determination (R2) of the three pseudo-ternary systems fitting was calculated. From the obtained results, the best HBA and HBD ratio in the DESs is elucidated as 1:2, the best molar concentration of DES is 0.1, and the NRTL model predicts the experimental data more accurately than the Wilson and UNIQUAC models. From the derived mechanism, the formation of stronger hydrogen bond and π–π bond interactions between DES and benzene is obtained when HBA and HBD ratio in DES is 1:2. In other conditions, the azeotrope cannot be broken, or the efficiency is low. The present work provides an environmentally friendly method to separate aromatic/aliphatic mixtures and act as a guide for further study of DESs in extractive distillation.

Deep Eutectic Solvents: An Eco‐friendly Design for Drug Engineering

“…The selection of an optimal molar ratio has been proven to produce DESs with a reasonable strength of hydrogen bonds [60] . Moreover, altering the molar ratio of a DES having the same constituents can change its physicochemical and functional properties such as density, viscosity, pH, and the extraction effect [61–64] . For example, the properties of the ChCl/ d ‐glucose eutectic system were analyzed at different molar compositions by Hayyan et al.…”

Is it correct to name DESs deep eutectic solvents?

“…As an example, mixtures of tetrabutylammonium bromide (HBA) and levulinic acid (HBD) with a molar ratio of 1:1, 1:2, 1:3 and 1:4, are all referred to as deep eutectic solvents (Bai et al 2021). Five systems with different components (namely choline chloride: ethylene glycol and choline chloride: glycerol) ratios are referred to as DES (Tang and Row 2013).…”

Advances in Deep Eutectic Solvents: New Green Solvents

“…For the application of DESs in the extractive distillation of benzene and cyclohexane mixtures, Bai et al [10] measured the density and viscosity of DESs at temperatures from 293.2 to 353.2 K and atmospheric pressures. The authors measured the VLE data of the ternary system (benzene + cyclohexane + DESs), and then used three thermodynamic models, NRTL, WILSON and UNIQUAC, to predicate VLE.…”