Experimental design and optimization of castor oil transesterification process by response surface methodology

In the present study, optimization of biodiesel production from castor oil was investigated. The biodiesel was produced in a large lab reactor (3 L) by an acid-catalyzed transesterification process, which was designed according to 2(3) full factorial central composite design (CCD). The response surface methodology (RSM) was used to optimize the reaction conditions to achieve maximum % fatty acid methyl ester (FAME) yield. Based on a second-order polynomial equation the optimum values of the three independent parameters thus obtained were 25:1 methanol/oil molar ratio, 3 vol. % catalyst amount and 60 degrees C reaction temperature. According to the experimental results, this process gave an average % FAME yield of 76.95%. The fatty acid composition of the oil was analyzed using a gas chromatograph (GC). The developed response surface model was also validated with two different, additional sets of experimental data, and its predictions were found to be within +/- 5% deviation. Using the RSM, the effect of variation in operating parameters as methanol/oil molar ratio, catalyst amount and reaction temperature and their interaction on % fatty acid methyl ester yield were also studied.