Chlorella biomass as a potential source of algal oil: Investigations on optimization of ultrasonic assisted extraction, kinetics and characterization of algal oil

The creation of renewable and affordable alternative energy is required due to the growing need for sustainable energy. In this present research work, algal oil has been extracted from microalgae biomass of Chlorella vulgaris using the Soxhlet apparatus. The algal biomass is ultrasonically pretreated to disrupt the cell walls of Chlorella sp. A total of five homogeneous solvent extractions are performed. As a result, the use of chloroform and isopropanol showed higher algal oil yields of 10.8% and 9.1%, respectively. Therefore, heterogeneous solvent approaches have been used in different volume ratios (5:1 to 1:5) to improve the yield of algal oil. Accordingly, the findings demonstrated that as compared to homogeneous solvents, the use of heterogeneous solvents shows better yield of algal oil from Chlorella sp. biomass. A maximum bio-oil yield of 12.3% was obtained using chloroform and isopropanol at a ratio of 3:3. To improve the extraction yields of algal oil, various parameters were optimized. The optimized parameters include 20 min of ultrasonication time, 3:1 ratio of solvent to biomass, temperature of 50 ℃ , and an extraction period of 90 min. Further, extracted algal oil is characterised using GC-MS, and the results shows the presence of octadecanoic acid in the extracted algal oil. GC-MS analysis of the extracted edalgal oil has shown the suitability of the oil for transesterification reaction for the production of fatty acid methyl esters.