Enhanced enzymatic saccharification of sugarcane bagasse pretreated by combining O2 and NaOH

• An effective pretreatment of sugarcane bagasse by combining O2 and NaOH was developed.
• O2–NaOH pretreatment offers advantages in lignin removal and enzymatic digestibility.
• Total sugar recovery from both pretreatment and enzymatic hydrolysis reached 89%.
• Susceptibility of substrates to enzymolysis was explained by their characteristics.

Sugarcane bagasse pretreated by combining O2 and NaOH with different variables was conducted to improve its enzymatic digestibility and sugar recovery, and the results were compared with sole NaOH pretreatment. Lignin removal for O2–NaOH pretreatment was around 10% higher than that for sole NaOH pretreatment under the same conditions, and O2–NaOH pretreatment resulted in higher glucan recovery in the solid remain. Subsequently, O2–NaOH pretreated sugarcane bagasse presented more efficient enzymatic digestibility than sole NaOH pretreatment. Under the moderate pretreatment conditions of combining 1% NaOH and 0.5 MPa O2 at 80 °C for 120 min, a high glucan conversion of 95% was achieved after 48 h enzymatic hydrolysis. Coupled with the operations of pretreatment and enzymatic hydrolysis, an admirable total sugar recovery of 89% (glucose recovery of 93% and xylose recovery of 84%) was obtained. The susceptibility of the substrates to enzymatic digestibility was explained by their physical and chemical characteristics.