Lignin is very abundant in nature, it is one of the three main components of lignocellulose, the only substance containing a benzene ring structure. Deep eutectic solvent (DES) is a considered sustainable biomass refining option, however, there is no systematic description and comparison of lignin extraction characteristics and process parameter characterization between DES process and DES combination process. This review is based on the efficient extraction of lignin by DES composed of lactic acid-choline chloride, and the process parameters and regenerated lignin properties of this DES are summarized (e.g., (a) DES composition; (b) reaction conditions; (c) raw material type; (d) third component; and (e) the combined process, and the effects on lignin extraction efficiency as well as quality). This review provides a detailed overview of the process of DES application in the field of lignin, specifically analyzing the composition, properties and synthesis methods of DES. This review also describes the structural characteristics of lignin, hemicellulose and cellulose and its solubility in DES. Finally, the outlook and direction of DES biomass refining based on the latest technology are presented.
Keywords: Deep eutectic solvent; Extraction; Lignin; Lignocellulose.
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