Production of Biodiesel from Microalgae Dunalliela Salina

In this research the possibility of biodiesel fuel production by methanolysis of Dunalliela Salina microalgae oil by use of whole cells of Rhizopus oryzae (R. oryzae) PTCC 5174 immobilized within biomass support particles (BSPs) of polyurethane as a biocatalyst (containing lipase) were investigated. Methanolysis was carried out with stepwise additions of methanol in every 24 h in the presence of 0.1M phosphate buffer (pH=6.8). The whole process was complete for 72 h. After separation of impurities by centrifugation, 59% conversion of methyl esters obtained in reaction of transesterification. To improve the conversion rate more methanol and solvent (acetone and normal hexane) were added to the reaction mixture which increased the conversion rate to 90% and 72%. The use of additional methanol resulted in enzyme inactivation. When methanol with molar ratio 2:1 was added; the conversion was reduced to 67%. The presence of a suitable amount of methanol in the reaction mixture is important because extra methanol causes the immobilized cells to lose their activities. From the results obtained in this method, unlike other methods, does not require complex process for product purification has a suitable conversion yield and can be used for large scale production.