Microwave-assisted lipid extraction from Chlorella vulgaris in water with 0.5%-2.5% of imidazolium based ionic liquid as additive

Microwave is a good candidate towards lipid extraction from microalgae in a bid to reduce the overall energetic consumption and extraction time. 1-octy1-3-methylimidazolium-based ILs belonging to 1st generation and 2nd generations, have been used. At 2.5% of [Omim][OAc] in the medium, 19.2% of lipid were obtained, while the conventional IL-less system only yielded 10.9%. More interestingly, the extraction efficiency increases with increasing amount of IL A broader range of fatty acid profiles was also found to be extracted in the presence of ILs. The lipid extraction ability of the ILs was further confirmed and even dramatically enhanced under high pressure microwave irradiation. At 1.5% IL, the lipid yield reached 37% with FAME profile mirroring the results obtained by hydrophobic IL based extraction. The energy balance calculation have shown a reduction in the energy loss with the different type of IL used resulting in a 12% net energy gain with the [Omim][NTf2] IL based extraction. A key finding in this study suggests that both the polarity of the ILs and the electronegativity of the anions play an important role in the type of lipids extracted. (C) 2019 Elsevier Ltd. All rights reserved.