Abstract A lard oil based biolubricant was synthesized through a two stage transesterification reaction. Raw lard oil was synthesized with methanol using potassium hydroxide as catalyst to produce a methyl ester for the first stage transesterification while the second stage involved the synthesis of the methyl ester and trimethylolpropane with sodium methoxide as catalyst to produce the lard oil based TMP ester. The optimization of the lard oil based TMP ester was carried out using a central composite design (CCD) of response surface methodology. The optimal conditions for the various independent variables were reaction temperature of 130 ºC, mole ratio of 1:4, catalyst weight of 1.5%w/w and reaction time of 180mins for a corresponding lard oil based TMP ester yield of 93%. Analysis of variance (ANOVA) of the response showed a quadratic regression model with interacting independent variables. Regression coefficient (R2) of 0.972 and a standard deviation of 0.631 implies that 97.2% of the changes in the response can be explained by the regression model. The lubricating properties of the lard oil biolubricant are as follows: pour point of -10ºC, flash point of 229ºC, viscosity index of 2.32, specific gravity of 0.92g/ml and kinematic viscosity of 40.51 and 10.22cSt at 40 ºC and 100 ºC respectively. This study showed that the properties of the lard oil based TMP ester meets the ISO VG32 grade requirement and has its potential as a base oil for gear oil in automobiles.
Keywords Biolubricant, transesterification, raw lard oil, trimethylolpropane, central composite design.