Synthesis of biodiesel by two-step transesterification from crude jatropha curcus L.oil using ultrasonic irradiation assisted

Abstract

Usually, the crude Jatropha curcas L. oil has very high free fatty acid (FFA) which obstructs thetransesterification reaction. As a result it provides low yield of biodiesel production. The objective of thisresearch is to investigate the optimum conditions for biodiesel production from crude Jatropha curcas L.oilwith methanol by ultrasonic irradiation (at 40 kHz frequency and 400 Watt) assisted, using two-step catalyzedmethod. In the first step, the reaction was carried out in the presence of sulfuric acid as an acid catalyst. Theproduct was then further transesterified with potassium hydroxide in the second step. The effects of differentoperating parameters such as molar ratio of reactants, catalyst quantity, operating temperature, and time ofreactants have been studied with the aim of process optimization. In the first step, the optimum conditions forthe acid catalyzed esterification process have been obtained as ratio of methanol to oil as 15% w/w, catalystconcentration of 3% w/w, temperature as 30ºC and reaction time as 20 minutes. For the second step, theoptimum conditions for the base catalyzed transesterification process have been obtained as ratio of methanolto oil as 15% w/w, catalyst concentration of 1% w/w, temperature as 30ºC, and reaction time as 40 minutes. Ithas been observed that the mass transfer and kinetic rate enhancements were due to the increase ininterfacial area and activity of the microscopic and macroscopic bubbles formed. The efficacy of usingultrasonic irradiation has been compared with conventional mechanical stirring method. The results indicatedthat the reaction time is much lower in the case of ultrasonic irradiation and high conversion as compared tostirring method.