Measurement of Liquid-Liquid Equilibrium Data and Study of Phase Behavior for Ternary Systems of Water, 4-Methyl-2-Pentanol, and Octanol Isomers

To address the difficulty in separating the azeotropic mixture of 4-methyl-2-pentanol (MIBC) and water by distillation, the liquid–liquid equilibrium (LLE) experiment was investigated using different octanol isomers as extractants. Ternary LLE data for the water + MIBC + octanol isomer (1-octanol, 2-ethylhexanol, 2-octanol) systems were determined at 303.2 K under 101.3 kPa. Based on the experimental data, distribution coefficients (D) and separation factors (S) were calculated. The results indicate that all three octanol isomers can effectively extract MIBC. Notably, 2-octanol exhibits a slightly higher separation efficiency, while 2-ethylhexanol demonstrates superior separation purity. The reliability of the experimental data was assessed using the Othmer-Tobias and Hand equations, with regression coefficients (R2) ≥ 0.99. Regression analysis using the NRTL and UNIQUAC models yielded data in good agreement with the experimental data. Finally, the GMcal_TieLinesLL tool was employed to validate the binary interaction parameters obtained from the regression, providing foundational data to support the simulation of extraction processes and the design of flow schemes for treating MIBC-containing azeotropic wastewater.