Phase Equilibrium Measurement and Thermodynamic Modeling for Separation of a 2-Methyl-2-butanol + Water Azeotrope System by Liquid–Liquid Extraction with Five Solvents

To separate the azeotropic system of 2-methyl-2-butanol and water, the liquid–liquid equilibria (LLE) data of water + 2-methyl-2-butanol + solvents (anisole, isoamyl alcohol, 1-octanol, ethyl acetate, methyl isobutyl ketone) were obtained at 308.2 K under 101.3 kPa, and all systems are Treybal’s type II. The distribution coefficient and selectivity coefficient were used to evaluate the effect of extraction and separation of water and 2-methyl-2-butanol. Meanwhile, quantum chemical methods were used to analyze intermolecular interactions. Finally, the Non-random Two Liquids and UNIQUAC thermodynamic models were used to correlate the LLE data to obtain binary interaction parameters with the RMSD being less than 0.19%. Meanwhile, the consistency of regression parameters of NRTL and UNIQUAC models was verified by the GUI-MATLAB tool.