Chapter 9 - Switchable green solvents for lipids extraction from microalgae

Abstract

Algae, with its high ability to grow in seawater by carbon dioxide (CO2) sequestration, can provide sustainable solutions for energy, water, food security, and sustainable land use. They can be considered as a potentially transformative feedstock and provide solutions to many pressing technoeconomic and environmental challenges the globe is facing today. Algae-based biofuels reduce consumption of fossil fuels. Most of the algal species are oil producers and are significantly higher than other crops like soybean, sunflower, canola, jatropha, and palm. Hence, it is a critical requirement to quantify the lipid content. There needs to be robust analytical procedures and facilities that can cater and support the technological needs of lipid extraction and estimation, as well as to provide quick, accurate, and reproducible results. Cost and the lipid production and extraction processes are the main influencing parameters for algal biodiesel production. Lipid extraction in microalgae is mainly performed by using conventional solvents or hydrothermal liquefaction (HTL). Usage of conventional solvents in lipid extraction influences the quality of the product (chlorophyll contamination) leading to poor quality product. To circumvent the problem, usage of green solvents (green extraction technologies) is more attractive in lipid extraction. The present chapter describes the types of solvent systems preferred in microalgal lipid extraction and methods of lipid extraction and estimation. It summarizes the challenges in this area of work and describes the status of analytical techniques. This provides a balanced perspective on the potential path in establishing holistic and integrated lipid extraction, solvents usage, and estimation facility.