Enhanced lipid recovery from chlorella sp. Biomass by green approach: A combination of ultrasonication and homogenization pre-treatment techniques (hybrid method) using aqueous deep eutectic solvents

Microalgae is renewable and sustainable biomass with high lipid content to produce third-generation microalgal biofuels and is considered as one of the best alternative biofuels to replace non-renewable fossil fuels. Cell disruption is an essential pre-treatment, necessary for the efficient extraction of lipids from the biomass before processing in biofuel production, but high-value energy requirement is an important issue for low-valued biofuels. This study investigated the hybrid pre-treatment method of microalgae species: chlorella sp. for enhanced lipid extraction by using a green approach i.e., combination of homogenization and ultrasonication technique along with green solvents. The study found increased lipid yield that suggested rupture of the outer cell wall of chlorella sp. which was sufficient to allow for the diffusion of aqueous deep eutectic solvent (aDES) for lipid extraction. The study on the hybrid methods with aqueous deep eutectic solvents indicated that lipid extraction enhanced from 13.05% in case of untreated biomass to 19.20%, 26.3%, 29.41%, and 30.65% for hybrid method-I, hybrid method-II, hybrid method-III, and hybrid method-IV respectively. GC-MS analysis of the extracted lipids identified the major component as Diethyl phthalate with enhanced yield at 40% and 17% respectively by the hybrid method III and IV in comparison to untreated biomass which is a value-added product having potential applications as a plasticizer and use in pharmaceutical & cosmetic industry. Copyright (C) 2022 Elsevier Ltd. All rights reserved.