Lipid recovery from deep eutectic solvents by polar antisolvents

Deep eutectic solvents (DES) can be a green alternative extraction technology for microalgae lipids, acting simultaneously as a pre-treatment agent and solvent. However, due to the low vapor pressure of both DES and lipid solute, the recovery of lipids and solvent regeneration remains difficult. In this study, we developed a novel strategy to separate the dissolved sunflower and model algae oil from imidazole/hexanoic acid DES by using polar antisolvents (water, methanol, and ethanol). The polarity and the amount of antisolvent influenced the lipid solubility in DES. While the water was the strongest antisolvent, the alcohols were easier to evaporate, ensuring easy DES regeneration. By adding small amounts of water and methanol, more than 90% of the lipids were recovered in the form of high-purity oils (>90%). In the case of ethanol, a large amount of ethanol was required, which diluted the solvent-rich phase and solubilized more lipids in it. Based on three repeated cycles with the selected antisolvent methanol, > 90% of the eutectic solvent could be regenerated.