Direct Conversion of Dry Algae to Biodiesel under Supercritical Methanolysis

The study demonstrates a one-step process and environmentally friendly approach for the direct conversion of dry algalbiomass to crude biodiesel under supercritical methanol conditions. Methanol is used for the simultaneous extraction and transesterification of lipids in algae to produce fatty acid methyl esters at supercritical conditions. The process conditions prevented the formation of by-products and the fatty acid methyl esters are produced from polar phospholipids, free fatty acids, and triglycerides. The effects of dry algae to methanol (weight/volume) ratio (1:12-1:40),reaction temperature (150-300°C), and reaction time (5–50 min.) on the yield of fatty acid methyl esters are studied. Conversion percentage reached97%at 300°C, molar ratio 1:30(weight/volume) and reaction time 30 minutes. The purity of fatty acid methyl esters is determined using Gas Chromatography analysis to record80%and alkyl ester content about77.6%.This green conversion process has the potential to provide an energy-efficient and economical route for biodiesel production with high efficiency of high predicted cetane number(60), high resistance for oxidation and low viscosity.