Enhanced bio-ethanol production from bamboo residues by alkali-aided Fenton reaction pretreatment and enzymatic saccharification

Alkali extraction was used to assist the Fenton pretreatment for overcoming the recalcitrance of bamboo and producing more sugar-based chemicals and bioethanol. The alkali-aided Fenton pretreatment showed the delignification of 55.33% and xylan removal of 80.76%. The surface lignin coverage, hydrophobicity, specific surface area, and cellulose crystallinity index were obviously changed by the combined pretreatment, which made cellulose accessibility increased by about 2-folds than Fenton pretreatment alone. The cleavage of β-O-4 linkage, the decrease of condensed structure and syringyl unit were observed in the residual lignin from the NaOH-Fenton pretreated D. brandisii, all of which reduced the nonproductive adsorption between enzymes and lignin. When NaOH-Fenton pretreated four bamboo residues were performed enzymatic hydrolysis, glucose yields of 66–74% and ethanol concentration of 11–16 g/L were obtained. The sequential NaOH-Fenton pretreatment should be considered as an environmentally-friendly bamboo biorefinery technology in the future.