Effects of Transesterification Parameters on the Biodiesel Produced from Crude Groundnut Oil

Abstract

This study focused on optimization of biodiesel yield from crude groundnut oil through a two-stage transesterification process by investigating the effect of reaction parameters on the yield using a 24 experimental factorial design. The crude groundnut oil was pretreated to remove water and reduce its FFA by esterification using sulphuric acid and ethanol followed by transesterification using sodium hydroxide and ethanol. The optimum ethyl ester (biodiesel) yield of 99% was obtained at optimum conditions of 1:6 wt/wt oil to ethanol molar ratio, reaction temperature of 60oC, catalyst concentration of 1.0 wt% and reaction time of 90 minutes. The biodiesel produced was characterized for fuel properties that include kinetic viscosity, cetane number, flash point etc. and the determined values were found to be within the acceptable standard as recommended by the ASTM D 6751. Statistical analysis of the 24 factorial experimental results was conducted using ANOVA, it was evidently proved that the four (4) reaction parameters i.e. molar ratio, catalyst concentration, reaction temperature and time had significant effects on the yield of the ethyl ester with their percentage contribution and effects being 29.6667% and 4.35, 6.27121% and -2, 38.2213% and 4.9375, 3.12801% and 3.12801 respectively. Also, it was proved that interaction between the reactions parameters had significant effect on the ethyl ester yield except the interaction between molar ratio-catalyst concentration-reaction time whose p-value was below the 95% confident level. A first degree linear mathematical model was developed and it was seen to completely describe the system and the model was further used to develop software that predicts biodiesel yield from crude groundnut oil using two-step transesterification process with ethanol and KOH as the catalyst.