(728b) Supercritical CO2 Modified with Mixed-Polarity Azeotropic Solvents for Extraction of Lipids From Algal Biomass

SC-CO₂ is cleaner green technology for extraction of algal lipids/oils for algal biodiesel production. Because of its non-polar nature, SCCO₂ is unable to interact with either polar lipids or neutral lipids that form complexes with polar lipids. The addition of a mixed –polarity azeotropic mixture with hexane/ethanol modifier, often referred to as hydrocarbon/alcohol co-solvents, enhances the fluid affinity towards neutral lipid as well as polar lipids to extract more quantity of total lipids. The major benefits of inducing mixed polarity solvents include higher lipid yield, favorable mass transfer, enhances the solvent properties, and production of quality lipid. The superior results can be possible with this system compared to SCCO₂ extraction with one solvent or without solvents.  SC-CO₂ uses moderate temperature and pressure so that it can be useful for the extraction of thermolabile compounds which may decompose at the temperature at which thermal methods are carried out. This study examines the effects of pressure, temperature, Co-solvents ratio and CO₂ flow-rate on lipid extraction yield and fatty acid composition and compares the results with SCCO₂ with hexane and SCCO₂ with ethanol methods. The algal biomass characterization and algal lipid analysis were performed using various analytical instruments such as FTIR, SEM-EDS, TEM, TLC, GC-MS and FTICR-MS. The lipid extracted-algae (LEA) from the processes are further processed for nutritional and toxicological analysis to demonstrate the suitability of algae biomass as a valuable feed supplement or substitute for conventional protein sources.