OPTIMIZATION OF BIODIESEL PRODUCTION FROM USED FRYING PEANUT OIL, AND ITS CHARACTERIZATION

Abstract

Biodiesel is produced through transesterification of oil with an alcohol and a base as a catalyst. This work aimed at employing used frying peanut oil for the production of biodiesel. The oil was transeterified using methanol and potassium hydroxide. The physicochemical analysis of used frying peanut oil revealed an acid value of 9.4 mg NaOH/g, free fatty acid (FFA) value of 6.63%, and specific gravity of 0.917. The high FFA content suggested the employment of acid esterification in the pretreatment stage. The biodiesel was produced and characterized, and compared with ASTM standards for fuel properties. Physiochemical properties of the produced biodiesel indicated specific gravity and pH values of 0.884 and 6.5, respectively. Biodiesel blends (B80 and B20) exhibited specific gravity and pH values of 0.876 and 0.832, and 6.9 and 6.3 respectively. This suggests the biodiesel's suitability for stand-alone or blended use in diesel engines. The functional groups of the biodiesel were investigated using FTIR spectroscopy. Influence of key parameters like reaction temperature, reaction time, catalyst concentration and methanol/oil molar ratio were determined based on optimized parameters of response surface methodology (RSM). An optimum yield of 78% was achieved with optimal conditions of methanol/oil molar ratio; 6:1, temperature; 55 oC, time; 75 min. This investigation has shown that used frying peanut oil can be utilized to produce biodiesel, and by replacing virgin peanut oil it improves cost effectiveness.