Influence of Temperature on the Liquid-Liquid Phase Equilibria of Ternary (Water plus Alcohol plus Entrainer) Systems

The effect of temperature on the liquid liquid equilibrium (LLE) phase behavior of ternary (water + alcohol + entrainer) systems comprised of the alcohols ethanol, isopropanol, and n-propanol and the entrainers diisopropyl ether (DIPE), cyclohexane, and isooctane (excluding (water + n-propanol + DIPE)) was investigated for application to the decanter in heterogeneous azeotropic distillation. LLE data were measured at ambient pressure for the (water + isopropanol + cyclohexane), (water + isopropanol + isooctane), and (water + n-propanol + isooctane) systems at 308.2 and 318.2 K and for the (water + n-propanol + cyclohexane) and (water + ethanol + isooctane) systems at 318.2 K. These data, in conjunction with literature LLE data, show that temperature has an effect on all systems investigated. As temperature increases, the aqueous phase becomes depleted of and the organic phase becomes enriched in alcohol. It appears that component polarities play an important role in explaining the phase behavior. The systems were correlated with the NRTL and UNIQUAC ACMs in Aspen Plus V8.2, but reliable correlations were only obtained for the (water + ethanol + DIPE/cyclohexane/isooctane) and (water + ethanol/isopropanol/n-propanol + cyclohexane) systems. These correlations were used to simulate the decanter water recoveries over a range of temperatures.