Improving enzymatic saccharification and ethanol production of bamboo residues with sulfomethylation-aided phosphoric acid pretreatment.

• The SPAP removed part of lignin and disrupted the crystalline regions of bamboo. • Glucose yield of SPAP-DS was 89.06 %, which was 4.5 times higher than PAP-DS. • Sulfomethylation contributed to the decrystallize of bamboo cellulose in the subsequent H 3 PO 4 -pretreatment. The sulfomethylation-aided phosphoric acid pretreatment (SPAP) was investigated for bamboo biorefinery. The yield of glucose and xylose were increased from 19.8 % and 13.88 % for H 3 PO 4 -pretreated D. sinicus alone (PAP-DS) to 89.06 % and 72.92 % for SPAP-DS. Ethanol concentration for SPAP-DS was 13.26 g/L, which improved by about 3-folds than PAP-DS. The SPAP-DS exhibited the lower lignin content and cellulose crystallinity, thus resulting in the enzyme accessibility to cellulose increased remarkably. The pre-step of sulfomethylation loosened compact structure of bamboo, which significantly contributed to the decrystallization of cellulose in the following H 3 PO 4 -pretreatment. The study has potential implications in biomass pretreatments, which should target synergistically and simultaneously toward cellulose, hemicellulose, or lignin fraction for obtaining higher bio-based chemical compounds and biofuels. [ABSTRACT FROM AUTHOR]