Improved enzymatic saccharification of bulrush via an efficient combination pretreatment.

[Display omitted] • Bulrush (BR) was effectively treated at 100 ℃ for 1 h (severity factor LogR o = 1.8). • NaOH-ChCl:Gly could remove lignin (80.1%) and xylan (66.8%) in BR. • The accessibility was greatly increased to 0.6 g/g BR via NaOH-ChCl:Gly treatment. • Treated BR had low hydrophobicity (1.56 L/g) and lignin surface area (417 m2/g). • The enzymatic digestibility of cellulose reached 87.9% after NaOH-ChCl:Gly treatment. Glycerol (Gly) was selected as hydrogen-bond-donor for preparing ChCl-based DES (ChCl:Gly), and the mixture of ChCl:Gly (20 wt%) and NaOH (4 wt%) was utilized for combination pretreatment of bulrush at 100 °C for 60 min (severity factor LogR o = 1.78). The effects of DES pretreatment on the chemical composition, microstructure, crystal structure, and cellulase hydrolysis were explored. NaOH-ChCl:Gly could remove lignin (80.1%) and xylan (66.8%), and the enzymatic digestibility of cellulose reached 87.9%. The accessibility of bulrush was apparently increased to 645.2 mg/g after NaOH-ChCl:Gly pretreatment. The hydrophobicity and lignin surface area were reduced to 1.56 L/g and 417 m2/g, respectively. The crystallinity of cellulose was increased from 20.8% to 55.6%, and great changes in surface morphology were observed, which explained the improvement of enzymatic hydrolysis efficiency. Overall, DES combined with alkali treatment could effectively promote the removal of lignin and xylan in bulrush, thus the relative saccharification activity was greatly affected. [ABSTRACT FROM AUTHOR]