Screening deep eutectic solvents as green extractants for oil from plant seeds based on COSMO-RS model

Deep eutectic solvents (DESs) have recently attracted considerable interest as eco-friendly alternatives for conventional solvents in many industrial separation processes. However, due to its vast number of possible combinations, reliable approaches for guiding the selection of task-specific DES remain limited. Using conductor-like screening model for real solvent (COSMO-RS), the solubility capacity was applied to screen 126 deep eutectic solvents to estimate their potential use as plant seed oil extractants. Moreover, DESs' σ-profiles were matched to σ-profiles of linoleic acid and glutamine, representing oil and oil protective protein membrane, to evaluate their molecule interactions. Results of COSMO-RS revealed that the DESs with higher linoleic acid solubility capacity showed lower solubility capacity for protein and vice versa. Moreover, σ-profiles of representative DESs demonstrated this behavior by comparing the similarity of DESs to both linoleic acid and protein. Consequently, DESs with high linoleic acid solubility could be used as individual solvents, while DESs with high protein solubility could be used as co-solvents with organic solvents. However, the experimental results proved that the use of DESs having high protein capacity, as co-solvents with diethyl ether, n-pentane and n-heptane raised the extracted oil yield. Utilizing ChCl:Gly (1:2) as a co-solvent with diethyl ether produced the highest yield of 30.7% compared to pure diethyl ether, which produced 27.0%.