Continuous and effective pretreatment of sugarcane bagasse lignocellulose with DBU/glycerol to enhance enzymatic saccharification

Abstract

The new deep eutectic solvent (DES) synthesized from 1,8-Diazabicyclo [5.4.0] undec-7-ene (DBU) and glycerol was utilized for the continuous pretreatment of sugarcane bagasse (SCB) and facilitating enzymatic saccharification. Under the optimal pretreatment conditions (DBU/glycerol weight ratio of 1:1.7, 160 ℃, 70 min) and enzymatic hydrolysis of the pretreated SCB by Cellulases Cellic CTec 2 (20 FPU per gram of substrate) at 50 ℃ for 72 h, the total reducing sugar content (TRSC) and total reducing sugar yield (TRSY) were 15.76 g/L and 0.51 g/g, respectively, and the lignin removal rate was 83.21%. After five recycles, the recovered pretreatment liquid maintained excellent pretreatment performance, where TRSC (14.68 g/L) and TRSY (0.48 g/g) can remain at high levels. Besides, the physicochemical properties of the DBU/glycerol solvent system were characterized, and the structural changes of SCB after pretreatment to enhance enzymatic hydrolysis were investigated by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and Fourier transform infrared analyzer (FT-IR). The results show that DBU/glycerol pretreatment is a green, efficient, and sustainable lignocellulosic pretreatment strategy.