Effect of different functional head groups of nonionic surfactants as lubricity additives in bio-hydrogenated diesel

Abstract This study addresses the poor lubricity of bio-hydrogenated diesel (BHD) by comparing two nonionic surfactants, sorbitan monooleate (Span 80) and glyceryl monooleate (GMO), as additives. Both additives improved lubricity at low concentrations, but Span 80, due to its polyhydroxylated sorbitan structure, demonstrated superior lubricity compared to GMO, which is attributed to stronger hydrogen bonding and more effective surface adsorption. These findings demonstrate that the molecular structure of the surfactant head group plays a crucial role in enhancing BHD lubricity, with Span 80 offering the most significant improvement. By improving the lubricity of BHD, this approach supports the protection of engine components and the broader adoption of renewable diesel fuels in commercial applications.