Sustainable solutions of using deep eutectic solvents for hemp degumming: A combined experimental and DFT study

Aiming at the problems of heavy environmental pollution, high energy consumption, and process complexity for current degumming techniques, three types of deep eutectic solvent (DES) systems as eco-friendly sustainable solutions including choline chloride/urea (CU), ethylenediamine hydrochloride/ethylene glycol (EE) and choline chloride/imidazole (CI) were prepared and applied to the degumming of seed hemp. It was clearly showed that all three DES systems exhibit excellent degumming efficiency on seed hemp to remove noncellulosic components involving in pectin, hemicellulose, and lignin in amorphous region without damage to the structure and crystalline morphology of cellulose, leading to an increase of cellulose portion from 54% to about 80%. CI with the molar ratio of 3:8 at 175 degrees C for 2.5 h give the best removal performance for hemicellulose and pectin while EE with molar ratio of 1:2 at 175 degrees C for 3 h can remove lignin with highest efficiency. However, CU with the lowest cost reveals a balanced removal of three noncellulosic components, which may be the optimal choice for industrial production. Furthermore, density functional theory analysis disclosed the essential information of configuration stability for three DES systems.