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source: Robbins, L. A., Chem. Eng. Prog., 76(10), 58-61 (1980), by permission.

source: Robbins, L. A., Chem. Eng. Prog., 76(10), 58-61 (1980), by permission.

for liquid-liquid behavior, as is for example the case for the methyl acetate-water and tetrahydrofuran-water systems. Homogeneous azeotropes that are completely miscible at all temperatures usually occur between species with very close boiling points and rather small liquid-phase nonidealities. Moreover, since strong positive deviations from Raoult's law are required for liquid-liquid phase splitting, maximum-boiling azeotropes (y, < 1) are never heterogeneous.

Additional general information on the thermodynamics of phase equilibria and azeotropy is available in Swietoslawski (Azeotropy and Polyazeotropy, Pergamon, London, 1963), Van Winkle (Distillation, McGraw-Hill, New York, 1967), Smith and Van Ness (Introduction to Chemical Engineering Thermodynamics, McGraw-Hill, New York, 1975), Wizniak [Chem. Eng. Sci., 38, 969 (1983)], and Walas (Phase Equilibria in Chemical Engineering, Butterworths, Boston, 1985). Horsley (Azeotropic Data-III, American Chemical Society, Washington, 1983) compiled an extensive list of binary and some ternary and higher experimental azeotropic boiling-point and composition data. Another source for azeotrope data and activity coefficient model parameters is the multivolume Vapor-Liquid Equilibrium Data Collection (DECHEMA, Frankfort 1977), a compendium of published experimental VLE data. Most of the data have been tested for ther-modynamic consistency and have been fit to the Wilson, UNIQUAC, Van Laar, Margules, and NRTL equations. An extensive two-volume compilation of data for 18,800 systems involving 1,700 compounds, entitled Azeotropic Data by Gmehling et al., was published in 1994 by VCH Publishers, Deerfield Beach, Florida. A computational method for determining the temperatures and compositions of all azeotropes of a multicomponent mixture, from liquid-phase activity-coefficient correlations, by a differential arclength homotopy continuation method is given by Fidkowski, Malone, and Doherty [Computers and Chem. Eng., 17,1141 (1993)].

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