Optimization of reactive extraction of castor seed to produce biodiesel using response surface methodology

Biodiesel was produced by reactive extraction (RE) of castor seed to reduce the cost and time associated with conventional method. The objective of this study is to determine the relationship between various important parameters of the RE process to obtain a high yield of FAME. Response surface methodology (RSM) was used to statistically analyze and optimize the operating parameters of the process. A central composite design (CCD) was adopted to study effects of catalyst concentration, methanol to oil molar ratio, reaction temperature and mixing intensity on yield of FAME. The results of RSM analysis indicate that catalyst concentration and methanol to oil molar ratio have most significant effect on the yield of FAME, with R2 = 0.998 shows fitness of a second-order model. The interaction terms of catalyst concentration with both methanol to oil molar ratio and reaction temperature exhibited a positive effect delivering (P < 0.0001). Based on second-order model, optimum condition for this reaction is found to be methanol to oil molar ratio of 225:1, catalyst concentration 1.0 wt.% of oil, reaction temperature 55 °C and mixing intensity of 350 rpm. The mathematical model (a quadratic polynomial equation) has developed adequately describing ranges of the experimental parameters studied and provides a statistically accurate prediction of the optimum yield of FAME.