Transesterification of oil extracted from different species of algae for biodiesel production

Abstract

In the current study, biodiesel production efficiency of Chlorella vulgaris, Rhizoclonium hieroglyphicum and mixed algae culture was measured by transesterification process. Growth rate of algal species was measured on the basis of increase in their dry matter in various media. Protein, carbohydrates and lipids in all selected algae were measured on dry matter basis. Extracted oil was analyzed for water contents, iodine value, saponification value, acid number and fatty acid composition. Transesterification of algal oil was performed by using sodium methoxide as a catalyst. Yield of biodiesel from extracted oil was calculated for C. vulgaris (95%), R. hieroglyphicum (91%) and mixed algae culture (92%). Produced biodiesel was analyzed for kinematic viscosity (4.9, 5.0 and 4.7 mm2/s), flash point (160, 156 and 155°C), specific gravity (0.91, 0.914 and 0.912 g/ml), cetain number (51, 49 and 47 min), iodine value (47, 53 and 49 mg/g), acid number (0.49, 0.5 and 0.46 mg.KOH/g), carbon residue (0.01, 0.02 and 0.01 mass%), sulfated ash (0.007, 0.003 and 0.004 mass%), sulphur (0.013, 0.012 and 0.01 wt%) and water contents (15, 23 and 17 mg/kg) for C. vulgaris, R. hieroglyphicum and mixed algae culture, respectively. Properties of biodiesel were compared with ASTM standards and it was found with high quality biodiesel.

Key words: Biodiesel, oil extraction, algae, transesterification.