An improvement study of biodiesel production from rice bran via non-catalytic in-situ transesterification using a subcritical water-methanol mixture

Abstract

A non-catalytic in-situ transesterification of biodiesel production from rice bran using subcritical water-methanol mixture was found to be unaffected by initial moisture and free fatty acids (FFA) contents. The method has been known as environmentally friendly conversion since no catalyst was used. Acid catalyst has an important role in in-situ transesterification due to their ability to accelerate the oil extraction from the bran and the reaction rate. In this study, CO2 as pressurizing gas was added into subcritical water methanol mixture to increased yield and content of biodiesel. Effect of different operation pressure (P = 40-100 bar) at subcritical water methanol mixture (T = 200°C) and reaction time of 180 min on the yield and content of biodiesel were investigated. Rice bran with initial FFA content of 40.42 % has been subjected into hydrothermal reactor together with water methanol mixture to produce rice bran oil (RBO)-based biodiesel. The more CO2 as pressurizing gas was added into the hydrothermal reactor, the more yield and content of biodiesel were obtained. The highest yield and content of biodiesel of 98.00±1.41% and 83.93%, respectively, were produced under P = 100 bar.