A clean and sustainable strategy to produce bio-lubricant with high-bearing and good anti-oxidation ability from Lanzhou lily

Abstract

Biolubricants like natural oil or grease are sustainable and renewable alternative to mineral lubricants. Poor thermo-oxidative stability and load-carrying capacity are the main obstacles limiting the application of bio-lubricants. Striving for a plant resource with plentiful ester analogues as base oil and other lubricating-benefit ingredients as natural additives may be a new and clean strategy to produce biolubricants with high-bearing and good oxidation stability. In this work, the bio-lubricant was extracted as Lanzhou lily crude extract (LLCE) from the widely cultivated crop Lanzhou lily (Lilium davidii var. unicolor) in China. Its lubricity, load-carrying capacity, and activity-composition relationship were investigated. LLCE exhibits good lubricity at temperature above 50 °C and extreme load-carrying capacity above 600 N. The friction coefficient at stable stage is about 0.12 and the wear rate of the steel discs is on the order of 10−7-10−8 mm3/Nm. These intriguing properties are attributed to the specific components in LLCE. Phenol esters or glycosides in LLCE is functional as base oil to provide the boundary lubrication, and other plentiful components like phospholipids, alkaloids, and organic sulfides play as natural additives to improve the lubricity and extreme pressure ability by accelerating the formation of tribo-reaction film. This work provides a sustainable and clean feedstock for high-performance bio-lubricants/additives and simultaneously expands the economic utilization of crops, which can be applied in the open lubricating systems like chainsaw, metal-cutting work and food-processing equipment in agricultural, food and manufacturer industries.