Model-free kinetics applied to volatilization of Brazilian sunflower oil, and its respective biodiesel

Model-free kinetic studies for volatilization of Brazilian sunflower oil and its respective biodiesel were carried out. The biodiesel was obtained by the methylic route using potassium hydroxide as catalyst. Both sunflower oil and biodiesel were characterized by physicochemical analyses, gas chromatography, simulated distillation and thermogravimetry. The physicochemical properties indicated that the oil and biodiesel samples are in accordance with the specifications of the Brazilian National Agency of Petroleum, Natural Gas and Biofuels (ANP). Gas chromatography indicated that the biodiesel was obtained with a content of ester of ca. 97.35 wt%. The TG curves indicated that the temperatures for volatilization of biodiesel are lower than for sunflower oil, which is explained by their different compositions and properties. The value of the apparent activation energy for the volatilization process, as determinated by the Vyazovkin Method, was higher for sunflower oil than for biodiesel.