ABSTRACT Microalgae oil of the species Chlorella protothecoides was obtained via a donation of the Soley Biotechnology Institute (SOLEYBIO) and characterized according to the fatty acid profile. Ethylic biodiesel was prepared using methods adapted by the research group. Analysis of acidity, water content, and density and viscosity temperature dependence (293.15 K to 368.15 K) were performed for the oil and ethylic biodiesel. The biofuel was characterized in terms of its flash and cloud points, heat capacity and cetane number. The properties studied were compared with conventional vegetable oils and biodiesel, presenting little differences and demonstrating the high viability of biodiesel from microalgae oil.

Abstract Phase equilibria of the reaction components are essential data for the design and process operations of biodiesel production. Despite their importance for the production of ethylic biodiesel, the reaction mixture, reactant (oil and ethanol) and the product (fatty acid ethyl esters) up to now have received less attention than the corresponding systems formed during the separation and purification phases of biodiesel production using ethanol. In this work, new experimental measurements were performed for the liquid-liquid equilibrium (LLE) of the system containing vegetable oil (sunflower oil and canola oil) + ethylic biodiesel of refined vegetable oil + anhydrous ethanol at 303.15 and at 323.15 K and the system containing refined palm oil + ethylic biodiesel of refined palm oil + ethanol at 318.15 K. The experimental data were successfully correlated by the nonrandom two-liquid (NRTL) model; the average deviations between calculated and experimental data were smaller than 1.00%.

Triacylglycerols and fatty alcohols are used in the formulation of cosmetic, pharmaceutical and food products. Although information about the phase transitions of these compounds and their mixtures is frequently required for design and optimization of processes and product formulation involving these substances, these data are still scarce in the literature. In the present study, the solid-liquid phase diagrams of two binary systems composed of triolein + 1-hexadecanol and triolein + 1-octadecanol were evaluated by differential scanning calorimetry (DSC) and optical microscopy. The experimental data were compared with predicted data by solving the phase equilibrium equations using an algorithm implemented in MATLAB. The liquid-phase activity coefficients were calculated using the Margules equation (two- and three-suffix) and the UNIFAC model (original and modified Dortmund model). The approaches used for calculating system equilibrium allowed an accurate prediction of the liquidus line with low deviations from the experimental data.

This work reports experimental tests using commercial spirits that were diluted and had their initial composition modified in order to better measure the distillation behavior of selected minor compounds of importance for the quality of alcoholic beverages. Such compounds were added to the commercial cachaça and the corresponding model wine, obtained after the spirits' dilution, was distilled. In this way a more precise distillation profile could be determined for those minor compounds. The alembic heating was performed by electrical resistance and the corresponding heat transfer coefficient was determined by analyzing the thermal behavior of the still during the distillations. A simulation algorithm was developed, including the mass and enthalpy balances as well as the heat transfer flux to the boiling wine. Good agreement between experimental and simulated results was obtained for the distillate rate, alcoholic graduation, temperature and most minor component profiles.

The water activity of aqueous solutions of EO-PO block copolymers of six different molar masses and EO/PO ratios and of maltodextrins of three different molar masses was determined at 298.15 K. The results showed that these aqueous solutions present a negative deviation from Raoult's law. The Flory-Huggins and UNIFAC excess Gibbs energy models were employed to model the experimental data. While a good agreement was obtained with the Flory-Huggins equation, discrepancies were observed when predicting the experimental behavior with the UNIFAC model. The water activities of ternary systems formed by a synthetic polymer, maltodextrin and water were also measured and used to test the predictive capability of both models.