Oxidation stability of biodiesel from different feedstocks: Influence of commercial additives and purification step

The present study investigates the effectiveness of three commercial synthetic (AO1, AO2 and AO3) and one natural (AO4) antioxidants to improve the oxidation stability of various biodiesel fuels produced from different vegetable oils: soybean methyl ester (SBME), rapeseed methyl ester (RME), high oleic sunflower methyl ester (HOSME) and palm methyl ester (PME) and prepared by two different purification steps, using distilled water and acidified distilled water (0.1 M citric acid solution) wash methods. The results of this study have shown that different biodiesel samples have different levels of oxidative stability. Antioxidants can improve the oxidation stability and the antioxidant effect increases as a function of its concentration. This study showed that the use of citric acid (0.1 M) instead of distilled water in the purification step improved the oxidative stability of biodiesel from different feedstocks, and the washing agent volume required resulted reduced. Results obtained were fitted to an equation in order to predict the minimum antioxidant dosage to meet EN 14214. The information generated in this study could be used to better understand the oxidation stability and its effect on the quality of pure biodiesel. (C) 2013 Elsevier Ltd. All rights reserved.