Role of Antioxidants in Enhancing Oxidation Stability of Biodiesels

Chemical composition of biodiesel plays an important role in deciding its oxidation stability. Bisallylic positions in fatty acid ester chain are especially prone to attack by oxygen, leading to the formation of gums, acids, and polymer deposits that cause failing or plugging problems in the engine and filter as consequences. Although oxidation of biodiesel cannot be checked completely, it can be slowed using antioxidants, which prevent the process from continuing by scavenging the free radicals, formed by the attack of oxygen on reactive sites of fatty acid ester chain. Antioxidants having phenolic and amine moiety have been found to be especially effective to enhance the stability. The mode of action and activity of various antioxidants have also been discussed.