Abstract：n-Hexane and isopropanol are widely used typical solvents in the chemical industry, and their binary system forms azeotrope when the mass fraction of isopropanol is 23%, which hinders the efficient separation and recovery of the solvents. To develop a functionalized ionic liquid extractant for the efficient separation of the azeotropic system, based on the COSMO-RS model, the extraction performance of 598 ionic liquids (ILs), formed by combining 26 cations with 23 anions, was evaluated. Analysis of ILs selectivity, solubility, and surface charge density distribution identified 1-ethyl-3-methylimidazolium acetate ([EMIM][Ac]) as the optimal extractant. Liquid-liquid equilibrium data for n-hexane-isopropanol- [EMIM][Ac] ternary system were determined experimentally at ambient temperature and atmospheric pressure. The separation performance of [EMIM][Ac] was quantified using the distribution coefficient (D) and selectivity coefficient (S). Data consistency was verified using the Othmer-Tobias, Bachman, and Hand equations, and the NRTL model successfully correlated the experimental data, yielding a root mean square deviation (δrms) of less than 3% and a correlation coefficient (R²) greater than 0.94, indicating high reliability of the experimental data. Molecular simulations were conducted using Gaussian 16W software. Through analysis of molecular electrostatic potential, interaction energy, interatomic interactions, and reduced density gradient, it revealed that strong hydrogen bonding between [EMIM][Ac] and isopropanol is the key mechanism for achieving efficient separation of the azeotropic system. This study demonstrated that the [EMIM][Ac] screened base on COSMO-RS model can effectively break the n-hexane-isopropanol azeotrope, providing a novel functionalized ionic liquid design strategy for separating alkane-alcohol azeotropic systems.
FAN Jungang,HAO Jiarui,CAO Yaxin et al. COSMO-RS Screening of Ionic Liquid for Extractive Separation of n-Hexane and Isopropanol Azeotrope[J]. Chemical Reaction Engineering and Technology, 2026, 42(2): 144-151.
