Characterization of Novel Deep Eutectic Solvent, Choline Chloride/Glutamic Acid, as Efficient Solvent for Lignin Dissolution

A novel amino acid-based deep eutectic solvent (DES), choline chloride (ChCl)/glutamic acid (Glu), was developed as a green renewable solvent for efficient biomass pretreatment. Spectroscopic analysis revealed that Glu is rapidly converted to pyroglutamic acid (pGlu) through dehydration during the DES formation. However, hydrogen bond formation differed between ChCl/Glu DES and DES formed by mixing ChCl/pGlu. Furthermore, lignin was dissolved readily at 10% concentration in ChCl/Glu DES, indicating significant potential for application of ChCl/Glu DES in lignocellulosic biomass pretreatment. A novel deep eutectic solvent (DES), choline chloride (ChCl)/glutamic acid (Glu), was developed as a green and renewable solvent by screening 20 common amino acids. 1H NMR and FT-IR revealed that Glu is rapidly converted to pyroglutamic acid (pGlu) through dehydration during the DES formation. ChCl/Glu DES facilitated rapid lignin dissolution, indicating significant potential for application in lignocellulosic biomass pretreatment.