Insight into key obstacles and technological strategy for enzymatic digestion of full cellulose fraction from poplar sawdust

Lignocellulosic biomass mainly consists of hemicellulose, lignin, and cellulose, which differently affect the enzymatic digestibility of cellulose. As for the typical representative for inert woody biomass, three components of cellulose were proposed conceptually for poplar sawdust, i.e., active cellulose, inert cellulose, and resistant cellulose. Dilute sulfuric acid pretreatment, hydrogen peroxide-sulfuric acid delignification, and sulfuric acidassisted glycerol swelling were, respectively, proven to break the three obstacle mechanisms that affect the cellulase of poplar. The removal of key obstacles improved the cellulase digestibility of poplar enzymehydrolyzed residues by 188.7 %, and glucose yield increased from 34.6 % to 99.9 %. Therefore, a total of 39.5 g glucose was obtained from 100 g poplar sawdust by integrating the above three technologies. This work presented insight into and removed the key obstacles to enzymatic digestibility of poplar cellulose and developed an integrated technology to effectively convert full cellulose fraction to glucose from woody biomass.