Investigation on the lubrication component and mechanism for a biolubricant isolated from the agro-waste resource of Codonopsis pilosula

Waste plant resource provides a new sustainable feedstock for the biolubricant, and purification of the effective components in biomass oil is vital to improve the performance of biolubricant. In this work, the crude extract of the aerial part of Codonopsis pilosula was divided into four different parts by petroleum ether, ethyl acetate, n -butanol and water, respectively. Their thermal stability, lubricating performances and mechanisms have been systematically investigated. In the four extracts, the petroleum ether extract displays the best thermal stability and lubricating performance over the entire test conditions, and other three extracts are confronted with lubrication failure at high loads and elevated temperatures. Triterpenoid saponin, typical for n-butanol extract exhibit the best lubricity at room temperature, followed by the fatty acid derivatives as phosphatidylcholine; flavonoid, and sugar exhibit poor lubricity. At high temperature, only the petroleum ether extract retains the good lubricity.