Liquid−Liquid(−Liquid) Equilibria in Ternary Systems of Water + Cyclohexylamine + Aromatic Hydrocarbon (Toluene or Propylbenzene) or Aliphatic Hydrocarbon (Heptane or Octane)

Abstract

Liquid−liquid equilibria and liquid−liquid−liquid equilibria were determined for (water + cyclohexylamine + toluene), (water + cyclohexylamine + propylbenzene), (water + cyclohexylamine + heptane), and (water + cyclohexylamine + octane) at temperatures of (298.15, 303.15, and 333.15) K at atmospheric pressure by photometric turbidity titration. The composition of conjugate phases was determined by gas−liquid chromatography or potentiometric titration and Karl Fischer titration. All systems show type I behavior since there is only one binary pair of partial miscible liquids. Surprisingly, the systems (water + cyclohexylamine + heptane) and (water + cyclohexylamine + octane) have a three-phase region in a limited temperature range. The data were predicted with the NRTL and the UNIQUAC models in comparison to the Elliott−Suresh−Donohue equation of state based on binary interaction parameters only.