Optimization of the production of biofuel form Jatropha oil using a recyclable anion-exchange resin

Abstract

The study of an anion-exchange resin (Amberlyst A26 (OH)) catalyzed transesterification of Jatropha (Jatropha curcas L.) oil was conducted to determine the effects of three variables: reaction temperature, ethanol: oil molar ratio and catalyst amount, on Jatropha oil conversion (XJO) and fatty acid ethyl esters yield’s (YFAEEs). The modified central composite design that involved three independent factors (temperature, ethanol: oil molar ratio and the catalyst present) with two levels, but not included the non-linear stage, was employed to optimize the process. From the main factors and their interactions, the ethanol: oil molar ratio was found to highly affect the XJO and YFAEEs. In this study, the statistical analysis showed that curvature is not significant (p ≤ 0.05), and thus, from the model regression equations, linear model was found to be more suitable to optimize the responses. By using the regression analysis and the response surface plots, the optimum XJO and YFAEEs of 37.63% and 36.31%, respectively were predicted to be obtained at the optimum temperature of 55 °C, ethanol: oil molar ratio of 35:1 and catalyst amount of 15%. Employing higher amount of catalyst reduced the XJO and YFAEEs, particularly, when the variable interacted with the reaction temperature.