Secondary amines as switchable solvents for lipid extraction from non-broken microalgae

Lipids from algal biomass may provide renewable fuel and chemical feedstock in large quantities. The energy intensity of drying and milling of algae prior to extraction and of solvent recovery afterwards is a major obstacle. The objective is to use switchable solvents to extract oil directly from wet microalgae slurries without the need for drying and milling, and subsequently recover the extracted oil and solvent by simple phase splitting, using CO2 as trigger. In this work secondary amine solvents were investigated for lipids extraction, polarity switching and phase splitting ability upon contacting with CO2. For strain Desmodesmus sp. extraction yields from the wet algal slurries, with and without cell disruption, were comparable with Bligh & Dyer method yields. Oil and solvent recovery via phase separation was realized by CO2 induced phase splitting, making secondary amines a candidate for further development of an energy efficient lipid extraction technology for non-broken microalgae.