Vapor-liquid equilibria of (Water + Glycerol), (Water + 1,3-Propanediol), or (Ethanol + Glycerol) binary mixtures at several temperatures: measurements and modeling
Résumé
Petroleum is the main energy source utilized in the world, but its availability is limited and the search for new renewable energy sources is of major interest. Biofuels, such as ethanol and biodiesel, are among the most promising sources for the substitution of fossil fuels. Biodiesel can replace petroleum diesel, as it is produced from animal fats and vegetable oils, which generate about 10% (w/w) glycerol as the main byproduct. The excess glycerol generated may become an environmental problem, since it cannot be disposed of in the environment. One of the possible applications is its use as carbon and energy source for microbial growth in industrial microbiology. Glycerol bioconversion in valuable chemicals, such as 1,3-propanediol, dihydroxyacetone, ethanol, succinate, .... The present paper is part of a research program concerning the thermodynamic properties of biofuels containing systems. In this presentation, the vapor-liquid equilibria of (water + glycerol), (water + 1,3-propanediol), and (ethanol + glycerol) binary mixtures measured using a static device at temperatures between 263 and 363 K are reported. The data were correlated with the Antoine equation. From these data excess Gibbs functions (GE) were calculated for several constant temperatures and fitted to a fourth-order Redlich-Kister equation using the Barker's method. The three binary systems exhibit positive deviations in GE for all investigated temperatures over the whole composition range. The NRTL, UNIQUAC and UNIFAC model have also been used and good results were obtained in the prediction of the total pressure and thermodynamic excess properties.