Comparison of several methods for effective lipid extraction from wet microalgae using green solvents

A comparative study of lipid extraction from microalgae was performed using the Soxhlet, Bligh and Dyer, Folch, and Hara and Radin methods, with the green solvents 2-methyltetrahydrofuran (2-MeTHF) and cyclopentyl methyl ether (CPME), which have also been used in previously published studies. Extractions were performed with the microalgae Chlorella pyrenoidosa at 65.71% moisture. The Bligh and Dyer methodology, using the solvents 2-MeTHF:isoamyl alcohol (2:1 v/v) and CPME:methanol (1:1.7 v/ v), extracted 95.73 +/- 0.52 and 89.35 +/- 7.98 mg lipids/g biomass, respectively. Regarding fatty acids yield, CPME showed higher selectivity than 2-MeTHF. A brief cost-effectiveness and energy analysis of the extraction process was performed. Based on the calculations, this study concluded that the energy required for the evaporation of the solvent and mixture of solvents after the extraction process has no significant economic impact; the largest expense is associated with solvent consumption. To extract 1 kg of fatty acids, the Hara and Radin method using hexane:isopropanol (3:2 v/v) proved to be the most costeffective. Results show that these solvents prices' are still not competitive when compared to fossil-based solvents. The price reduction of 2-MeTHE would make it more attractive than CPME, as it requires a lower amount of biomass. (C) 2019 Elsevier Ltd. All rights reserved.