Ammonium sulfite pretreatment of wheat straw for efficient enzymatic saccharification

Pretreatment is an important upstream process that affects the economics of biofuels production from lignocellulose. This study established a novel pretreatment process for efficient bioconversion of wheat straw using ammonium sulfite as pretreatment option. Effects of temperature, time, ammonium sulfite concentration and sodium carbonate supplementation level on pretreatment were evaluated. 99.9% of glucan and 88.0% of xylan were hydrolyzed with 35 FPU cellulase and 70 FXU xylanase (per gram of dry biomass) in 24 h after pretreatment by 20% (w/w) ammonium sulfite supplemented with 4% (based on ammonium sulfite dosage) sodium carbonate at 180 °C for 1 h. Total monosaccharide yield of 0.413 g/g native wheat straw was achieved with 82.6% acid insoluble lignin removal. Characterization results of flourier translation infrared spectrum revealed that lignin can be removed by sulfonation and ammonolysis. The results in the research provide an efficient method for lignocellulose pretreatment.