Ionic Liquids: A Plausible Future of Bio-lubricants

Abstract

This paper reviews the development of bio-lubricants from conventional impeller pressed natural oils to a new class of green bio-lubricants referred to as ionic liquids (ILs) at room temperature. The attraction to bio-lubricants began with natural oils due to their low friction and wear characteristics owing to high lubricity. To better control the tribological behavior, natural oils were introduced to additives, such as lamellar solid powders. Looking to the future, room-temperature IL lubricants derived from biological feedstock are seen as prospective alternatives and solutions to the issues associated with currently available bio-lubricants. Hence, a comprehensive investigation on the tribological properties of novel bio-based IL lubricant is carried out. A simplistic IL feasibility study has also been performed wherein pin-on-disk tests were conducted to analyze the friction and wear behavior under ambient conditions. The ILs demonstrate improved tribological performance when compared to conventional petroleum-based and bio-based lubricants in their purified forms at various levels. The mechanisms concerning the chemical composition of the ILs and their tribological properties imbibed by the bio-lubricants are discussed while highlighting its plausible industrial application.