Efficient fractionation of lignocellulosic biomass with high sugar yields and adequate lignin integrity has become a crucial challenge for biomass upgradation, especially via environmentally benign ways. Screening of a series of choline chloride (ChCl)‐based ternary deep eutectic solvents (DESs) indicated that additional glycerol in acidic DESs generally promoted enzymatic hydrolysis of pretreated wheat straw. Pretreatment by a natural deep eutectic solvent (NADES) composed of ChCl, lactic acid, and glycerol performed noticeably and was examined with regard to key process factors. The pretreatment achieved 71.2% delignification, 55.3% xylan removal, and a glucose yield of 77.2% by enzymatic hydrolysis upon optimization. Structural characterization indicated modified surface morphology, increased crystallinity, disrupted lignocellulosic structures, and enlarged specific surface area. Extracted lignin exhibited a high content of β‐O‐4 linkages (45.3 per 100 aromatic units), suggesting its good structural integrity. Mechanisms pertaining to biomass fractionation and lignin protection were tentatively proposed. More than 80% of the DES can be recovered after five cycles while maintaining an enzymatic glucose yield above 51.0%. This work revealed the characteristics and potential of a natural acidic polyol‐based DES in biomass fractionation comprised of commonly available and eco‐friendly components, which may have implications in establishing an efficient and sustainable biorefinery strategy.
Guo et al. (Tue,) studied this question.