Microwave-Assisted Subcritical Water Extraction of Lipids From Wet Algae

Microwave-assisted extraction of algal oil at subcritical water conditions was demonstrated with wet algae samples containing up to 90% of water. The extraction efficiency of this method was compared to those of the conventional solvent extraction methods, Folch and Bligh & Dyer. The extraction parameters including biomass loading, temperature and extraction time are optimized after executing a set of designed experiments. Algal oil was produced after purification of bio crude with activated charcoal. The residual algal biomass was also analyzed for its fatty acid and energy content to validate potential byproduct development as part of algal biorefinery. Energy calculations were performed for microwave assisted subcritical water extraction and compared with those of the conventional methods. Analytical instruments including GC-MS, FT-ICR were used to analyze the biomass and biocrude. Thermogravimetric analysis (TGA), TEM and SEM equipped with EDS were used to characterize the biomass in different stages of the extraction process.