Experimental and Modeling Studies of the Reaction Kinetics of Alkaline-Catalyzed used Frying Oil Glycerolysis using Isopropyl Alcohol as a Reaction Solvent

Abstract

An alkaline catalyzed glycerolysis of used frying oil using sodium hydroxide and isopropyl alcohol as solvent was investigated. A reaction kinetic model considering glycerol-triglyceride solubility and a second order kinetic mechanism was also developed. The effect of variations in glycerol to used frying oil molar ratio (RGO = 2:1 to 4:1) and temperature (60 to 80ºC) on the rate of reaction were investigated, while the isopropyl alcohol to used frying oil ratio (2:1 v/w) and the concentration of catalyst (3 wt% based on used frying oil) were held constant. Results showed that both RGO and temperature affected the glycerolysis reaction kinetic, with the effect of RGO was found to be superior. The proposed model showed its good agreement with the experimental data. Glycerolysis at RGO = 3:1 and 80ºC in 90 min was found to be a relatively good condition, where 91.03% of tryglceride was converted into MG.