A combined sodium phosphate and sodium sulfide pretreatment for enhanced enzymatic digestibility and delignification of corn stover

Na 3 PO 4 and Na 2 S were employed as efficient alkaline catalysts for the pretreatment of corn stover. To systematically obtain optimal conditions, the effects of critical pretreatment parameters including sodium phosphate concentration (1–4%), sulfidity (0–20%), pretreatment temperature (100–120   °C), and reaction time (20–60   min) on the reducing sugar yield of pretreated substrates were evaluated in a lab-scale using the response surface methodology. Pretreated under the sodium phosphate concentration of 4%, sulfidity of 10%, temperature of 120   °C, and reaction time of 40   min, the reducing sugar yield and glucose yield of the pretreated corn stover achieved 91.11% and 64.01%, respectively, with a moderate enzyme loading of 30   FPU/g substrate. Additionally, a strong correlation (R 2   =   0.971 and R 2   =   0.954) between the delignification and the reducing sugar yield (or glucose yield) was observed by this pretreatment method. These results evidently support that the combined Na 3 PO 4 -Na 2 S pretreatment is an effective and feasible method for processing lignocellulosic biomass.