Microwave assisted biodiesel production from crude Pongamia pinnata oil using homogeneous base catalyst (KOH) was unsuccessful because of considerable soap formation. Therefore, a two step process of biodiesel production from high free fatty acid (FFA) oil was investigated. In first step, crude P. pinnata oil was acid catalyzed using H2SO4 and acid value of oil was reduced to less than 4 mg KOH/g. Effect of sulfuric acid concentration, alcohol-oil molar ratio and microwave irradiation time on acid value of oil was studied. Result suggested that 1.5% H2SO4 (w/w), 6:1 methanol oil molar ratio and 3 min microwave irradiation time was sufficient to reduce the acid value of oil from 12 and 22 mg KOH/g to 2.9 and 3.9 mg/KOH/g, respectively. Oil obtained after pretreatment was subsequently used for microwave assisted alkali catalyzed transesterification. A higher biodiesel yield (99.0%) was achieved by adopting two step processes. Microwave energy efficiency during alkali catalyzed transesterification was also investigated. The results suggested a significant energy saving because of reduced reaction time under microwave heating.
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Abstract Introduction Materials and Methods Materials Microwave assisted acid esterification Microwave assisted transesterification Ester content and fuel properties of biodiesel Determination of specific heat of P. pinnata oil Estimation of electrical energy consumption Results and Discussion Physical and fuel properties of P. pinnata oil Microwave assisted single step alkali catalyzed transesterification Microwave assisted esterification Alkali- catalyzed transesterification Fuel properties of P. pinnata biodiesel Energy consumption during microwave assisted transesterification Conclusions Acknowledgements References