Sustainable green solvents and techniques for lipid extraction from microalgae: A review

S.P. Jeevan Kumar, Garlapati Vijay Kumar, Archana Dash, Peter Scholz, Rintu Banerjee

Microbial Biotechnology and Downstream Processing Laboratory, Department of Agricultural and Food Engineering, Indian Institute of Technology, Kharagpur 721 302, India.

Abstract

Energy security is a serious concern for a sustainable economy where it has necessitated alternative renewable energy that can have the potential to meet the futuristic needs. Among renewable energies, carbon neutral biofuels from microalgae appear to be a promising move towards sustainability and cleaner fuels owing to its attributes of high CO₂-sequestering capability, high lipid productivity and being easily cultivable in an open pond and waste/marine/brackish water. However, the commercial viability of algae-based fuels suffers mainly from the cost incurred during the process. Among the steps involved in the biodiesel production from microalgae, lipid extraction in particular consumes not only a significant amount of energy and time but also causes environmental contamination by usage of toxic solvents. Conventional solvents used in lipid extraction process may further aggravate the quality of the product by dissolving other compounds like chlorophyll that may lead to erroneous results of lipid content. To circumvent the problem, green solvents and process intensification methods/techniques (green extraction technologies) potentially improve the characteristics of energy reduction, eco-friendliness, non-toxicity and efficient lipid extraction. Hence, this review focuses on the prospects of green solvents and extraction techniques that could improve the commercial viability of biodiesel production.

Graphical abstract

Keywords: Enzyme-assisted extraction; Fluorous solvents; In situ transesterification; Ionic liquids; Switchable solvent; Terpenes.