PRODUCTION AND ASSESSMENT OF JATROPHA CURCAS OIL BASED BIOLUBRICANT FOR LIGHT GEAR APPLICATIONS

ABSTRACT

The jatropha curcas oil was extracted from the seed with the use of a soxhlet apparatus with petroleum ether as the solvent for oil extraction. The extracted oil was subjected to physiochemical characterisation to determine the its density, acid value, free fatty acid value (FFA) content, kinematic viscosity at 50˚C and 100˚C , its viscosity index and saponification value. A value of 15.2% was determined for the FFA which is above the threshold value for oils to be used as lubricant thus indicating that virgin Jatropha curcas seed oil is unsuitable for use as lubricant in its raw form. Thus the raw, unaltered jatropha curcas oil was pre-treated via esterification using methanol and this reduced the FFA content to 0.51%. This pre-treated oil with lower FFA was then subjected to a two stage transesterification process.  The first stage saw the oil transformed into its methyl esters (FAME) and the second stage transforming the methyl ester through polyol transesterification with ethylene glycol resulting in the synthesis of the biolubricant. The synthesised biolubricant was assessed for conformance with current industrial standard lubricant and its tribological and thermal properties were in line. The biolubricant had pour point, kinematic viscosity at 50 ˚C and 100˚C, and viscosity index determined to be -8˚C, 59.25cSt, 11.52cSt and 191.15 respectively. These values showed that the formulated biolubricant exhibits favourable properties even at low temperature, stable viscosity-temperature behaviour, and perfect lubricative properties. These performance parameters were found to be in tandem with ISO VG-46 commercial lubricants which are utilised in light and industrial gear applications.

Keywords: Jatropha curcas, biolubricant, two stage transesterification, tribological and thermal properties, oil extraction, physiochemical characterisation