Optimization of biodiesel production by solid acid catalyst derived from coconut shell via response surface methodology

Abstract The application of solid acid catalyst in biodiesel production eliminates the tedious pretreatment of feedstock and eradicates generation of high volume of wastewater. A novel acid catalyst was prepared via sulfonation of incompletely carbonized coconut shell using concentrated sulfuric acid. The design of experiments were performed using four factor-three-level central composite design coupled with response surface methodology to evaluate the interaction between two factors in order to determine the optimum process conditions. A quadratic model was suggested for the prediction of biodiesel yield. The F-value and p-value of the model were 4.02 and 0.0129, respectively, indicate that the model was statistically significant at 95 per cent confidence interval. In addition, R 2 value of the model was 0.8364, which indicates the acceptable accuracy of the model. From the optimization study, it was found that the carbonization temperature, carbonization time, sulfonation temperature and sulfonation time were 422 °C, 4 h, 100 °C and 15 h, respectively. At these optimum conditions the predicted and observed biodiesel yield were 88.15 per cent and 88.03 per cent, respectively, which experimentally verified the accuracy of the model. The use of coconut shell-derived solid acid catalyst in biodiesel production promotes the sustainable and green way of operations.