Efficient Synthesis of Biodiesel From Waste Cooking Oil Catalysed by Al2O3 Impregnated with NaOH

Due to the high price of virgin vegetable oils and the drawbacks of the homogeneous catalytic transesterification, in this work an economically profitable alternative process was proposed for biodiesel synthesis in which transesterification of the low-cost waste cooking oil (WCO) with methanol in a heterogeneous system was done. Alumina impregnated with sodium hydroxide was utilized as a solid base catalyst along with a high yield and less waste streams. The optimum combination for transesterification reaction was determined as methanol-to-oil molar ratio 7:1, catalyst amount 1.5%, reaction time 4 hr and reaction temperature 70oC. At this optimum condition, the fatty acid methyl ester (FAME) yield was over 92%. Fourier Transform Infrared spectroscopy (FT-IR) was the assessing technique for detection of biodiesel and glycerol in this work and biodiesel’s physical properties including flash point, fire point, density, kinematic viscosity, cloud point, pour point and acid value have also been measured which satisfied the requirement of the international standards.