Intensification of biolubricant synthesis from waste cooking oil using tetrahydrofuran as co-solvent

In this study, biolubricant was synthesized through two stages of transesterification. The first transesterification was the reaction between waste cooking oil and ethanol using sodium hydroxide as catalyst to produce fatty acid ethyl esters (FAEE). The second transesterification was the reaction between FAEE and 1-octanol using potassium hydroxide as catalyst with tetrahydrofuran as co-solvent to produce fatty acid octyl esters (biolubricant). This study was focused on the effect of tetrahydrofuran as co-solvent in the second transesterification. Biolubricant yield of 94.42% was obtained at reaction conditions (temperature of 125°C, time of 180 min, reactant molar ratio of 1:4, catalyst amount of 1%-w/w, vacum pressure of 100 mmHg and co-solvent amount of 25%-w/w). The physico-chemical properties of biolubricant were kinematic viscosities of 10.47 mm²/s and 2.75 mm²/s at 40°C and 100°C, viscosity index of 103 and acid number of 0.62 mg KOH/g.