Isothermal vapor-liquid equilibria, excess molar volume and the deviation of refractive indices for binary mixtures of 1-butanol, 1-hexanol, 3-methyl-1-butanol and butyl acetate

Experimental vapor-liquid equilibrium (VLE) data and mixture properties are reported toward developing a process for the separation of the traditional ABE (acetone + butanol + ethanol) fermentation. Isothermal VLE measurements at 343.2 K were performed by using headspace gas chromatography (HSGC) for binary systems {1-butanol + 3-methyl-1-butanol}, {1-butanol + 1-hexanol}, {butyl acetate + 3-methyl-1-butanol}, {butyl acetate + 1-hexanol} and {3-methyl-1-butanol + 1-hexanol}. The experimental VLE binary data were correlated using the Wilson, NRTL and UNIQUAC activity coefficient model equation. In addition, a digital vibrating tube densimeter and precision digital refractometer were used to determine the excess molar volume (VEVE) and the deviation of the refractive indices (ΔRΔR) for the same binary systems at 298.2 K. The Redlich-Kister equation was employed to show that the determined VEVE and ΔRΔR data were well correlated.