Effect of oxidation of Jatropha curcas-derived biodiesel on its lubricating properties

The oxidation of a Jatropha curcas-derived biodiesel was accelerated through the Rancimat method. High-frequency reciprocating friction, wear testing and gas chromatography coupled with mass spectrometry (GC-MS) were utilized to analyze the influence of composition changes during the oxidation of Jatropha biodiesel on its lubricating properties. This research indicated that: The polar functional ester group of Jatropha biodiesel could be adsorbed on a metal surface to form a physical adsorption membrane, while its carbon-carbon double bond would enhance the electrostatic force among the adsorbed membrane molecules, to improve the lubricating properties of Jatropha biodiesel; the oxidation had a significant effect on the lubricating properties of biodiesel. The peroxides generated by the short-time oxidation would stimulate the decomposition of the fatty acid chain, destroying the stability of the lubricative adsorption membrane. The highly polar products and epoxy compounds formed at the later stage of oxidation contributed to the formation of a stable boundary film on the metal surface and enhanced the lubricity of biodiesel. (C) 2019 Published by Elsevier Inc. on behalf of International Energy Initiative.