Bioethanol production has increased in demand as a replacement for conventional fuels. This work studies the use of apple pomace, which corresponds to 45% (w/w) of dehydrated apple production, as a reliable and inexpensive source for bioethanol production. Additionally, the vinasse obtained from the process as a byproduct is analyzed. Apple pomace has important properties for energy purposes, with high soluble sugar (6%–8%), organic compounds and low protein content. The carbohydrates were consumed in 99.3% in 144 h at a temperature of 30 °C and in a yeast Saccharomyces cerevisiae (YSC) concentration of 0.10 g/L. The bioethanol purity produced, 99.5% (v/v), was quantified by gas chromatography and calorific value (23.21 MJ/kg). This high purity, which fulfills the EN 15376, ASTM D 4806 Standard, allows its use as a fuel and oil additive. Moreover, it can be stated that vinasse obtained from alcohol distillation is a compound that has physicochemical values like other vinasses. Finally, Chile, as the most important exporting country of dehydrated apples in the world, has great potential to take advantage of the use of this raw material for bioethanol and vinasse production.

This work focuses on the application of a two-way approach, where Molecular Dynamics (MD) simulations and the Square Gradient Theory (SGT) have been used for describing the phase and interface behavior of binary and ternary Lennard-Jones (LJ) mixtures, along a condition of three-phase equilibrium. The unequivocal correspondence between MD and SGT has been achieved by using the global phase diagram of binary mixtures composed by equally sized Lennard-Jones molecules, from which representative molecular parameters for Type-I, Type-II, and Type-III systems have been determined. The so selected binaries have been used then to scale the behavior of a ternary mixture characterized by complex phase equilibrium patterns. For the case of the theoretical SGT approach applied to the Lennard-Jones equation of state was used for predicting phase equilibrium and interfacial properties. In addition the corresponding MD simulations of these macroscopic properties have been conducted for the LJ potential by using equivalent molecular parameters and conditions than in the theoretical approach. Excellent agreement has been observed between the predictions obtained from theory and simulations. Particularly, our results concerning the characterization of the three phase line of a binary Type-III mixture indicate that the bulk liquid (α) and the bulk gas (G) regions are sharply separated by a bulk liquid region (β) for all the explored temperature, pressure, and concentration conditions. The structural analysis of these bulk phases reveals that a secondary liquid phase (β) perfectly wets the liquid-gas interface (α-G), as previously found for Type-II mixture [A. Mejía and L. F. Vega, J. Chem. Phys. 124, 244505 (2006)]. The exploration along the three-phase line for the ternary mixture shows good agreement between SGT and MD. Particularly, we observed the specific influence of a third component in the phase and interface behavior. From all the previous results, we conclude that the SGT applied to an EoS with appropriate mixing rules produces reliable predictions of the properties of ternary mixtures.