The Production and Optimization of Biodiesel from Crude Jatropha Curcas Oil by a Two Step Process—An Indian Case Study Using Response Surface Methodology

Experiments were conducted to produce biodiesel from crude Jatropha Curcas oil (CJCO) having high free fatty acid content (6.85%) in two steps. During the first step, the free fatty acid content of CJCO was reduced to 1.12% in 1 hour at 60°C, using 9:1 methanol to oil molar ratio and 1%w/w of oil of H2SO4. The second step was alkali catalyzed transesterification of pretreated CJCO to produce biodiesel and the factors affecting the biodiesel yield were optimized using response surface methodology. The effect of five level-three factors and their reciprocal interactions on biodiesel yield were studied. A total of 20 experiments were designed and conducted to study the effect of reaction temperature, catalyst amount, and oil to methanol ratio on biodiesel yield. A second-order polynomial regression model was fitted and found adequate with R2 of 0.9722. The model predicted that the highest yield of methyl ester would be 93.55% at the following optimized conditions: reaction temperature of 61.5°C, alkali catalyst of 0.58% w/w of oil and an oil to methanol molar ratio of 1:5.93. Using these optimal factors under experimental conditions in three independent replicates, an average of 92.5 ± 0.5% yield was achieved and the value was well within the range predicted by the model.