Vapor-Liquid Equilibrium of Ethyl Lactate Highly Diluted in Ethanol-Water Mixtures at 101.3 kPa. Experimental Measurements and Thermodynamic Modeling Using Semiempirical Models

A thermodynamic study of the vapor-liquid equilibrium for the ternary system ethyl lactate-ethanol-water was performed at 101.3 kPa and infinite dilution regarding ethyl lactate, for boiling temperatures ranging from (352.3 to 370.0) K. The experimental measurements were carried out with a recirculation still and the equilibrium compositions of ethyl lactate were determined by gas chromatography. The volatility of ethyl lactate decreases when the ethanol content in the liquid phase is increased. The investigated system was correctly correlated by the NRTL and UNIQUAC models, with an average absolute relative deviation below 10%. The comparison with the results obtained from interaction parameters fitted to experimental data of the binary systems ethyl lactate-ethanol and ethyl lactate-water at 101.3 kPa, proves that the parameters calculated in this work give a better description of the ethyl lactate volatility, a key parameter in distillation, at low concentrations. These latter parameters are therefore recommended for process simulation and optimization in alcoholic beverages production.