Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, People's Republic of China; Key Laboratory of Forestry Genetics & Biotechnology (Nanjing Forestry University), Ministry of Education, Nanjing 210037, People's Republic of China. Electronic address: [Email]
A novel combined pretreatment process of poplar sawdust was established in this study based on the sequential acetic acid and alkali treatment with poly (ethylene glycol) diglycidyl ether (PEGDE). Effects of each treatment step on chemical composition, cellulose accessibility, and enzymatic digestibility of poplar sawdust was investigated. Acetic acid pretreatment remarkably increased cellulose accessibility while also producing a relatively high quantity of xylooligosaccharides (XOS) (37.6% of raw xylan). However, enzymatic digestibility remained low (28.3%) despite hemicellulose disruption. Post alkali treatment was next applied, leading to improvement on cellulose accessibility and enzymatic hydrolysis. Enzymatic hydrolysis was improved more significantly by successive alkali treatment with PEGDE. Its potential mechanisms attributable to enzymatic hydrolysis improvement were explored by revealing the changes to lignin properties. This work successfully demonstrated that recalcitrant waste woody biomass can be biorefined into both high-value XOS as well as relatively high yield of fermentable sugars.