José M. Goenaga

Temperature Dependence of Excess Molar Volumes of Ethanol + Water + Ethyl Acetate

In order to design and optimize equipment needed for production of distilled alcoholic beverages, an adequate knowledge of their physical properties and phase equilibria is necessary. The key thermodynamic information needed is for those chemicals that are the main components in terms of nonideal behavior. In this paper we present the temperature dependence of the excess molar volumes of the ternary system ethanol + water + ethyl acetate in the range 288.15–323.15 K at atmospheric pressure, due to the importance of ethyl acetate among the flavor compounds contained in this type of beverage. The observed excess molar volumes are usually negative over the whole homogeneous composition range, but take on positive values as the binary ethanol + ethyl acetate system is approached and the liquid phase separation region is observed. Because the current process designs are strongly computer oriented, the accuracy of theoretical model predictions was examined. The experimental data were used to test the capability of the Soave–Redlich–Kwong (SRK) equation of state to predict the ternary mixture behavior from binary mixture interaction parameters, which were obtained from previously published data. Derived properties, such as partial the excess molar volumes, excess isobaric expansibility, and the pressure derivative of excess molar enthalpy at constant temperature were calculated, due to their importance in the study of specific molecular interactions.

Influence of temperature on ultrasonic velocity measurements of ethanol + water + ethyl acetate mixtures

The ultrasonic velocity of the ternary mixtures ethanol + water + ethyl acetate at the range 288.15–323.15 K and atmospheric pressure, has been measured over the whole concentration range. The corresponding change of isentropic compressibility was computed from the experimental data. The results were fitted by means of a temperature-dependent equation, the parameters of which have been gathered in this experiment. The experimental ultrasonic velocities have been analyzed in terms of different theoretical models, an adequate agreement between the experimental and predicted values both in magnitude and sign being obtained, despite the high non-ideal trend of the studied mixture. The obtained experimental values indicate varying extent of interstitial accommodation among unlike molecules as a function of steric hindrance attending to ethyl acetate composition as key component and as a function of hydrogen bond and temperature attending to ethanol composition as key component.

Influence of temperature on thermodynamic properties of substituted aromatic compounds

This work presents experimental liquid densities and ultrasonic velocities for a collection of substituted aromatic compounds (isobutylbenzene, 1,3,5-trimethylbenzene, butylbenzene, isopropylbenzene, p-xylene, m-xylene and o-xylene) at the range of temperature 278.15–323.15 K and atmospheric pressure of a collection of halogenated and aromatic hydrocarbons. Fitting equations were applied to data in order to correlate for later computer-based design. The estimation of the studied properties was made by the application of different theoretical procedures. An equation of state based on the generalised Van der Waals theory which combines the Staverman–Guggenheim combinatorial term of lattice statistics with an attractive lattice gas expression and the free length theory (FLT) showed a good response at the studied conditions.

Vapor–liquid equilibria for binary mixtures containing ethyl tert butyl ether (ETBE) + (p-xylene, m-xylene and ethylbenzene) at 101.3 kPa

Isobaric vapor–liquid equilibria data at 101.3 kPa were reported for the binary mixtures ethyl tert butyl ether (ETBE) + (p-xylene, m-xylene and ethylbenzene). VLE experimental data were tested for thermodynamic consistency by means of a modified Dechema test and was demonstrated to be consistent. The activity coefficients were correlated with the Margules, van Laar, UNIQUAC, NRTL, and Wilson equations. The Analytical Solution Of Groups (ASOG) model also was applied for prediction.

Phase behaviour of ethanol + water + ethyl acetate at 101.3 kPa

Must distillation processes simulation is a challenging task, due to the lack of thermodynamic interaction parameters and accurate studies of phase equilibria. The presence of polar substances, those different from ethanol and water, and their low concentrations make it very difficult to model industrial distillation. Several of the congeners are essential enological components of the organoleptic matrix. In this work, we are concerned with the study of phase behaviour of ethanol + water + ethyl acetate at 101.3 kPa, this being the third compound, the legal congener of the highest composition in common alcoholic distillation. The experimental results showed partial miscibility and four azeotropes into a complex medium. Group contribution models yield poor results. Disposable literature was compared and commented upon. The lack of experimental data in multicomponent alcoholic distillation mixtures and the low reliability of the group contribution methods suggest a prudent application to process simulation.

Isobaric phase equilibrium of the ternary mixture ethanol + water + 2-propanol

Simulation of the distillation of wine and must is a challenging task due to the lack of thermodynamic information because of scarcity of accurate studies of phase equilibria. Simulation of these processes is rather complicated because of the presence of polar substances (called congeners) at very low concentration. This work studies the phase behavior of the ternary system, ethanol + water + 2-propanol at 101.3 kPa being the third compound one of the most important legal congener in common alcoholic distillation. Experimental results showed that this system exhibits two binary minimum azeotropes. Prediction of activity coefficients and equilibrium compositions with different UNIFAC group contribution models showed poor accurate results. Consistency of experimental data was tested by the McDermott–Ellis method. In addition, disposable literature was compared and commented upon. The lack of experimental data in multicomponent alcoholic distillation mixtures and the low reliability of the group contribution methods suggest a prudent work into simulation of alcoholic distillation.