Determination of vapor-liquid equilibrium at far-subatmospheric pressures by using headspace chromatography

Isothermal VLE data for the ethanol-n-butyl acetate binary system at 303.15 K, 313.15 K, and 318.15 K, and for the cyclohexane-2-propanol binary system at 298.15 K and 303.15 K, have been determined using headspace chromatography. These data have not been reported in the literature. The thermodynamic consistency of the T-x-y data in the present work has been tested by means of the Herington area test method. The checked results conformed to the requirement of thermodynamic consistency. The parameters of the NRTL and the Wilson model for the two binary systems have been respectively optimized by the simplex method according to both the experimental VLE data presented in the paper and the data published in the literature (Gmehling et al., 1978a, Gmehling et al., 1982) for each system. They were expressed as a function of the temperature from 303.15 to 353.15 K and from 298.15 to 333.15 K. Correlation results were satisfactory.