Sequential Aqueous Ammonia Extraction and LiCl/N,N-Dimethyl Formamide Pretreatment for Enhancing Enzymatic Saccharification of Winter Bamboo Shoot Shell

Effective utilization of winter bamboo shoot shell (BSS) is of great interest, since BSS provides a renewable and inexpensive bioresource for the production of biofuels. In this study, an effective combination pretreatment by the sequential aqueous ammonia (25 wt%) extraction at 50 °C for 24 h and LiCl/ N , N -dimethyl formamide (LiCl/DMF) (6 wt% of LiCl) pretreatment at 50 °C for 8 h was used for pretreating BSS. SEM, FTIR, and XRD results indicated that combination pretreatment could effectively remove lignin and change the crystal structure of cellulose for promoting enzymatic saccharification. Additionally, significant linear correlations were found about solid recovery-delignification ( R 2 = 0.9235), delignification-reducing sugars ( R 2 = 0.9552), and delignification-hemicellulose removal ( R 2 = 0.9779) during the combination pretreatment. The reducing sugars and glucose from the hydrolysis of 100 g/L pretreated BSS could be obtained at 72.3 and 40.5 g/L, respectively. Using the recovered BSS-hydrolysates containing 20–50 g/L glucose as carbon source, the ethanol yields at 48 h could be obtained at 84.5–86.1% of the theoretical yield. In conclusion, the sequential ammonia extraction and LiCl/DMF pretreatment has high potential application in future.