Enzymatic in situ saccharification of sugarcane bagasse pretreated with low loading of alkalic salts Na2SO3/Na3PO4 by autoclaving.
Sugarcane bagasse (SCB) is an abundant, renewable and inexpensive agricultural byproduct for the production of biofuel and other biobased products. To effectively saccharify SCB with cellulases, combination with dilute alkali salts Na2SO3/Na3PO4 (0.4% Na3PO4, 0.03% Na2SO3) at 7.5% sulfidity and hot water (DASHW) in "one-pot" pretreatment media by autoclaving at 110°C for 40min was attempted to pretreat SCB in this study. Furthermore, FT-IR, XRD and SEM were employed to characterize the changes in the cellulose structural characteristics (porosity, morphology, and crystallinity) of the pretreated Na2SO3/Na3PO4-SCB solid residue, which indicated that combination pretreatment could effectively remove lignin and hemicellulose for enhancing enzymatic saccharification. After 72h, the reducing sugars and glucose from the enzymatic in situ hydrolysis of 50g/L Na2SO3/Na3PO4-SCB in dilute Na2SO3/Na3PO4 (0.27% Na3PO4, 0.02% Na2SO3) media were obtained at 33.8 and 21.8g/L, respectively. Finally, the SCB-hydrolysates containing 20g/L glucose were used for ethanol fermentation in the presence of dilute alkali salts. After 48h, the ethanol yield was 0.42g ethanol/g glucose, which represents 82.1% of the theoretical yield. In conclusion, this study provided an effective pretreatment strategy for enhancing SCB's saccharification, which has potential application of other lignocellulosic materials.