Utilization of waste vegetable oil methyl esters as lubricant oil

Abstract

Increasing environmental awareness and threats to the environment have made the recycling of biomass products necessary. The goal of this paper is to study the tribological properties of fatty acid methyl esters derived from waste frying oils under different lubrication conditions. For this purpose, the performance of candidate fatty acid methyl esters was compared with a mineral base oil. For the determination of tribological properties, a pin-on-disc wear tester was used. The experiments were carried out in three replications at different loads (5, 10, and 15 N) and different sliding speeds (100, 300, and 600 r/min) and a 1000 m sliding distance under dry, boundary-mixed, and fluid lubrication conditions. After the wear amount of the test specimens was determined by the mass loss method, their Archard wear indexes were calculated. Scanning electron microscopy surface images were used for visual analysis and energy-dispersive X-ray spectroscopy images for chemical analysis. The surface contact angles and surface tensions of the lubricant test specimens were also measured experimentally. In all experimental results, it has been found that the tribological properties of used frying oil fatty acid methyl esters such as friction, wear, and surface adhesion are generally better than the base oil under all lubrication conditions. Fatty acid methyl esters is a biodegradable, recycling, and environmentally friendly product and can be confirmed as a lubricant and/or an oil additive candidate.