Assessment of antioxidant action of curcumin during storage of commercial biodiesel produced from soybean oil and beef tallow

Abstract

Biodiesel has emerged as an alternative source to fossil fuels. In Brazil, to assign a good quality to biodiesel, regarding oxidation stability, it is necessary that the biodiesel shows a minimum of 8 h of induction period (IP), determined at a temperature of 110 °C by the Rancimat method, in accordance with Resolution No. 45/2014 of ANP. As, in most cases, the biodiesel produced does not meet the established standards of oxidation stability, it is necessary to add antioxidants, which slow down the oxidative process. Thus, this paper proposes a study on the action of curcumin, a natural antioxidant, on commercial biodiesel produced from blending 80% soybean oil and 20% beef tallow. In this study, samples were stored for 180 days at 43 °C, according to ASTM D4625 recommendations. It was possible to observe that curcumin ensured greater oxidation stability to biodiesel and lower acid number values during the period of storage. Kinetic studies showed that samples with the addition of curcumin showed the highest value of activation energy for the oxidative degradation process, demonstrating that adding this natural antioxidant makes biodiesel more resistant to oxidation.