Methanol-Based Transesterification Optimization of Waste Used Cooking Oil over Potassium Hydroxide Catalyst

Abstract

Problem statement: Waste used Cooking Oil (WCO) harmfully affected to environment and human’s health can be a feedstock for producing biodiesel. Approach: The conversion of Fatty Acid and Free Fatty Acid (FFA) of WCO with 15.0% w/w FFA content to biodiesel was studied through transesterification reactions. This work investigated the effects of alcohol and catalyst quantity, reaction time and temperature on the FFA conversion and biodiesel production and also determines the optimum condition. Results: The optimum use of 5% w/w potassium hydroxide (KOH) catalyst at 70°C for 2 h yielded 88.20% FFA conversion and 50% biodiesel recovery of WCO. For the reaction rate analysis, based on Arrhenius equation, the activation energy of 47.07 kJ.mo1^-1 and the pre-exponential factor of 7.58×10¹⁰ min^-1 were obtained using pseudo first-order model. In addition, the produced biodiesel was blended with diesel in the volumetric proportions of 5:95 (ExB5), 20:80 (ExB20) and 50:50 (ExB50) and characterized by FT-IR, in order to compare to biodiesel blend sold in local gas station (B5). It was observed that the ExB5 has exhibited the same functional group as of the B5. Conclusion: The produced biodiesel may be used in diesel engines if other properties are tested for compatibility. This provides one more choice for alternative energy and commercialization.