| Summary: | 碩士 === 靜宜大學 === 應用化學系 === 101 === In this day, the liquid-liquid equilibria (LLE) for the quinary system of water + methanol + 2-propanol +2,2,4-trimethylpentane + p-xylene were conducted at 298.15 K and 318.15 K respectively. The liquid-liquid equilibria of the multicomponet systems investigated are: water + methanol + (2,2,4-trimethylpentane 50mol% + p-xylene 50mol%), water + (methanol 75mol% + 2-propaol 25mol%) + (2,2,4-trimethylpentane 50mol% + p-xylene 50mol%), water + (methanol 50mol% + 2-propaol 50mol%) + (2,2,4-trimethylpentane 50mol% + p-xylene 50mol%), water + (methanol 25mol% + 2-propaol 75mol%) + (2,2,4-trimethylpentane 50mol% + p-xylene 50mol%), water + 2-propaol + (2,2,4-trimethylpentane 50mol% + p-xylene 50mol%) were studied. The liquid-liquid phases after equilibrium were determined by g.l.c. measurements. The experimental LLE data of the multicomponent systems were correlated with the NRTL and UNIQUAC solution models with satisfactory results.
The multicomponent systems are depicted as the ternary mixtures and the phase diagrams in the form of Gibbs triangles with both the experimental and calculated tie-lines are presented. The solubility curve data for the studied multicomponent systems were determined by the cloud point method. The reliability of the experimental tie-line data was confirmed using the Othmer-Tobias equation. Each system exhibited a large partially miscible region. The region of heterogeneity was found to decrease with an increase of temperature or blending of 2-propanol with methanol. The water composition in the organic phase and the hydrocarbon solubility in the aqueous phase at different temperatures are illustrated in terms of the amount of (methanol+2-propanol) in the global composition. The water composition in the organic phase and the hydrocarbon solubility in the aqueous phase were found to increase with an increase of the amount of 2-propanol or an increase of temperature.
The densities, viscosities, refractive indexes of each conjugated phase located in the tie-lines have been determined for the multicomponent systems. It is observed that these data of each conjugate phase are valuable toward the understanding of the degree of solubility of the multicomponent systems. These observations may be important when appraising the water pollution potential of gasoline reformulations and the sensitivity of the gasoline to water.
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