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.
Isothermal vapor-liquid equilibrium data were measured at 333.15 and 363.15 K for the systems toluene + phenol, toluene + 2-cresol, toluene + 3-cresol, toluene + 4-cresol, octane + 2-cresol, octane + 3-cresol, water + phenol, and water + 3 cresol. Additionally, heteroazeotropic data of water + 2-cresol and water + 4-cresol were determined. The solubility of water in 2-cresol, 3-cresol, and 4-cresol was measured by photometric turbidity titration. Excess molar volumes for the systems toluene + phenol or cresols and octane + 2 cresol or + 3 cresol are presented together with Redlich-Kister polynomial fits. The VLE data and, if present, LLE data have been regressed according to the models NRTL, UNIQUAC, and Elliott Suresh Donohue equation of state together with data from the literature.
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
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