Phase Equilibria and Mechanism Insights into the Separation of Isopropyl Acetate and Methanol by Deep Eutectic Solvents

Abstract

Separation of methanol−isopropyl acetate (IPAC) obtained via isopropanol synthesis is essential. Deep eutectic solvents (DESs) have garnered extensive attention in the field of azeotropic separation owing to their advantages such as biodegradability, ecofriendliness, and cost-effectiveness. In this work, three cholinebased DESs were prepared. Then, the experimental data of the synthesized DESs with methanol and IPAC were measured, which were linearly correlated with Hand and Othmer−Tobias equations. The G M /RT surface obtained using GUI-MATLAB software was used to determine the reliability of the fitting data based on the NRTL model. Choline chloride and ethylene glycol DES with a molar ratio of 1:2 exhibited the best methanol affinity. The effect of the solvent structure was studied using a combination of experimental and quantum chemistry and molecular dynamics (MD) calculations. Through electrostatic potential distribution, atoms-in-molecules, and independent gradient model analytical methods, the three DEEs were primarily extracted via a hydrogen bond interaction and van der Waals interaction, wherein the former played a dominant role in separation. MD simulation was used to reveal the effect of the structures of hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs) on the extraction process at the molecular level. The analysis results indicated that HBA was the main influencing factor in the separation, and the electrostatic interaction of Cl − and methanol was dominant in the separation. Additionally, HBDs were the secondary factor during the separation process. In this work, the reasons for the differences in the separation performances of different DESs were analyzed from a microscopic perspective, offering theoretical support for selecting suitable DESs for separating alcohol-containing azeotropic systems.

Screening of Green and Environmentally Friendly Deep Eutectic Solvents and Study on Molecular Mechanism and Process for Separation of Isopropanol and Cyclohexane

“…To eliminate the effects of repulsive forces, the energy of the virtual box is minimized. After reaching the specified temperature of the system, it is necessary to equilibrate in the NPT ensemble for 50 ns, with data saved every 5 ps . VMD is used to analyze the structural characteristics of the extraction process.…”

Phase Equilibrium of p-Xylene and Isobutanol in Ionic Liquid Separations: Thermodynamic and Mechanistic Analysis

“…Moreover, MD simulation has also made some progress in the analysis of the mechanism of LLE. 24 Chen et al 25 used MD simulation to elucidate the basic mechanism of acetone-methanol azeotrope separation using ILs and found that the strong interaction between methanol and dimethylphosphate was responsible for the azeotrope elimination. Dai et al 26 Screening of ILs.…”

“…The results showed that the key to the separation is the strong hydrogen bond between the O atom of the anion in the ILs and the H atom in TFP. Moreover, MD simulation has also made some progress in the analysis of the mechanism of LLE . Chen et al used MD simulation to elucidate the basic mechanism of acetone-methanol azeotrope separation using ILs and found that the strong interaction between methanol and dimethylphosphate was responsible for the azeotrope elimination.…”