Hydrotropic Cloud Point Extraction of Lipids from Microalgae: A New Pathway for Biofuels Production

Abstract

The solubilization of fatty acids by small amphiphiles such as butyl ethylene glycol, butyl or pentyl diethylene glycol, and hexyl triethylene glycol, also called hydrotropes, was demonstrated by the determination of their phase diagram. They were thus applied for the passive extraction at room temperature of lipids from Dunaliella salina microalgae. The extraction yield of the lipidic fraction (mainly coming from glycolipids), could reach up to 81%, depending of the nature of the hydrotrope and its concentration. In addition, their cloud point properties allow the easy separation of the organic fraction, and their low boiling points allow their recovery with a lower energetic cost than the energetic content of the solubilized lipids. They can also directly be used for the transesterification of the lipids to give the corresponding fatty esters, which may be used as biofuels.