Esterification of High Free Fatty Acid Rice Bran Oil: Parametric and Kinetic Study

R. Arora, A. P. Toor and R. K. Wanchoo

Abstract
The esterification of free fatty acids (FFA) in rice bran oil (RBO) with methanol in the presence of sulfuric acid as a homogeneous catalyst was studied. The effects of catalyst concentration (0.15 to 1.0 wt%), reaction temperature (318 K to 333 K), and molar ratio of oil to methanol (1:5 to 1:30) on the conversion of FFA were investigated to optimize the conditions for maximum conversion of FFAs. A detailed kinetic study was carried out using second-order pseudo-homogeneous kinetic model. The kinetic parameters were obtained and activation energy was determined from the Arrhenius plot. The activation energy of 23.21 kJ mol–1 and pre-exponential factor of 32.65 L mol–1 min–1 was obtained under the optimum catalyst concentration of 0.5 wt %, stirring speed of 500 rpm and oil to methanol ratio 1:20.

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Keywords
biodiesel, esterification, high free fatty acid oil, homogeneous catalyst, kinetics