Effect of temperature on the oxidation of soybean biodiesel

Abstract

This paper proposes to examine the effect of temperature on the oxidation behavior of biodiesel. Soybean biodiesel was oxidized at different temperatures (room temperature, 60, and 110 °C), and the increase in primary and secondary oxidation products was determined based on the peroxide and anisidine values, respectively, during the induction period (IP). The results indicated that the evolution of hydroperoxides followed zero-order reaction kinetics during the IP at all temperatures, and their rate of formation was exponentially affected by temperature. It was also deduced that temperature influenced the ratio between primary and secondary oxidation products formation, which decreased as the temperature increased. Additionally, it was possible to predict the oxidation behavior of the soybean biodiesel at room temperature by an exponential model fitted to the IP values at different temperatures (70, 80, 90, 100, and 110 °C) using the Rancimat apparatus.