Liquid–Liquid Equilibrium for the Extraction of 2-Methyl-2-butanol from Water with Six Solvents at 308.2 K under 101.3 kPa: Experimental and Theoretical Analysis

To separate the azeotropic system of 2-methyl-2-butanol and water, the liquid–liquid equilibrium (LLE) data of water + 2-methyl-2-butanol + solvents (methyl tert-butyl ether (MTBE), isopropyl ether, isooctyl alcohol, methyl acetate, mesityl oxide, and 4-methyl-2-pentanol (MIBC)) were measured at 308.2 K under 101.3 kPa. All systems conform to Treybal’s type II ternary phase behavior, with water + solvents and water + 2-methyl-2-butanol being partially miscible binary mixtures, while 2-methyl-2-butanol + solvents are miscible binary mixture. The distribution coefficient (D) and selectivity coefficient (S) were employed to evaluate solvent performance for extracting 2-methyl-2-butanol from water. Intermolecular interactions between 2-methyl-2-butanol and both solvents and water were investigated by using the DMol3 module. The nonrandom two-liquid (NRTL) and universal quasi-chemical (UNIQUAC) models were applied to correlate LLE data, obtaining binary interaction parameters with root-mean-square deviations (RMSDs) < 0.60%. The consistency of regression parameters for both models was validated using the GUI-MATLAB tool.