Two Wertheim-based association models, the simplified PC-SAFT and the Elliott-Suresh-Donohue (ESD) equation of state, are compared in this work for the description of vapor−liquid equilibria (VLE) and liquid−liquid equilibria (LLE) in binary systems of aniline, cyclohexylamine (CHA), hydrocarbons, and water. Furthermore, the predictive capabilities of the models are investigated for four ternary systems composed of these components, which exhibit complex liquid−liquid(−liquid) equilibria (LLLE). Various aspects of association models which have an influence in the results are studied for the PC-SAFT equation of state, e.g., the choice of various association schemes for the amines and parametrization of water as well as different approaches for describing solvation. It is shown that simplified PC-SAFT using water parameters estimated in this work can describe successfully water−alkane LLE. In general, both models perform overall similarly for the binary systems, although ESD shows a remarkably good behavior despite its simplicity and the use of only the two-site scheme for all associating compounds. The prediction of the LLE in the ternary systems water + octane + aniline and water + CHA + aniline is satisfactory whereas larger deviations were obtained for the systems water + octane + CHA and octane + CHA + aniline.

The liquid-liquid equilibria (LLE) and liquid-liquid-liquid equilibria (LLLE) in eight ternary systems were determined by photometric turbidity titration at atmospheric pressure. Additionally, the compositions of coexisting phases were determined with analytic methods. The measurements in the systems heptane or octane þ phenol þ water were realized at temperatures of (313.15 and 333.15) K. The equilibrium data in the systems heptane þ 2-cresol or 3-cresol or 4-cresol þ water and octane þ 2-cresol or 3-cresol or 4-cresol þ water were estimated at temperatures of (298.15 and 323.15) K. The excess Gibbs energy nonrandom two-liquid (NRTL) and universal quasichemical (UNIQUAC) activity coefficient models as well as the Elliott-Suresh-Donohue equation of state (ESD EoS) were used to predict the LLE or LLLE in the investigated ternary systems. The binary interaction parameters were calculated using vapor-liquid and LLE data from the literature or data predicted with the modified universal quasichemical functional-group activity coefficient (UNIFAC Dortmund) model.

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.

The liquid-liquid equilibria were determined in the ternary systems toluene þ phenol or 2-cresol or 3-cresol or 4-cresol þ water and ethylbenzene þ phenol or 2-cresol or 3-cresol or 4-cresol þ water at atmospheric pressure at temperatures of 298.15 K and 313.15 K or 323.15 K by photometric turbidity titration. The liquid-liquid equilibria in the ternary systems were predicted with the excess Gibbs energy models NRTL and UNIQUAC as well as the Elliott-Suresh-Donohue equation of state. Binary interaction parameters were calculated on the basis of available vapor-liquid and liquid-liquid equilibrium data and data predicted with the modified UNIFAC (Dortmund) model. ' RESULTS AND DISCUSSIONExperimental Data. The liquid-liquid equilibria of eight ternary systems are determined at two different temperatures at atmospheric pressure. The experimental data are reported in the Supporting Information. The binodal curves indicate a type 2 character in all investigated systems agreeing to the classification of Treybal. 10 The binary mixtures of aromatic hydrocarbons þ phenols are homogeneous over the whole concentration and temperature range. By contrast, a large miscibility gap occurs in binary