Biomass pretreatment using biomass-derived organic solvents facilitates the extraction of lignin and enzymatic hydrolysis of glucan

In this study, biomass-derived organic solvents (GVL, THF, and ethanol) were used to pretreat lignocellulosic biomass to facilitate the extraction of lignin and enzymatic hydrolysis of glucan. Under the same pretreatment conditions (120 degrees C, 30 min, 0.5 wt% H2SO4), the GVL cosolvent exhibited a high lignin removal value of 62.80%. The enzymatic saccharification of residual cellulose-rich solid reached 82.59%. The extracted lignin showed a low molecular weight of 3264 g/mol and a good chemical structure according to characterization by SEM, FT-IR, GPC, and 2D-HSQC NMR. Moreover, a QC calculation was performed to explore the interactions between the lignin model compound and solvent molecules to understand the reasons for the differences in lignin dissolution of these three solvents. The H center dot center dot center dot OH length and bonding energy (Delta E) in the complex of VG-GVL were calculated to be 1.852 angstrom and 19.4 kcal/mol, respectively. The results indicated that a strong hydrogen bonding interaction was formed between VG and GVL, which explained why GVL had a higher lignin removal capacity than the other solvents under the same pretreatment conditions. In summary, the current study provided a valuable reference for lignocellulose pretreatment toward the extraction of lignin and enzymatic hydrolysis of glucan.