Influence of Molecular Structure on the Physicochemical and Tribological Properties of Biolubricants: A Review

The increase in the price of crude oil, the environmental impact, or the depletion of fossil resources has increased the need for bio-based alternatives. This has led to the search for renewable, biodegradable, and environmentally friendly raw materials to obtain lubricants that meet these characteristics. This review deals with the state of the art of biolubricants along with their most common raw materials and molecular structures, processes of chemical modification of bio-oils, as well as the relationship between their structural features and physicochemical/tribological properties. This review concludes that the production of fatty acid alkyl esters from vegetable oils is the most promising chemical route to produce a wide range of biolubricants through double transesterification reactions. It also highlights the need to explore this route for the production of microalgae-derived biolubricants due to its environmental benefits during cultivation and production processes.