A stepwise pretreatment of sugarcane bagasse by alkaline and hydroxymethyl reagent for bioethanol production

Reducing the lignin inhibition in the enzymatic digestibility is essential to obtain high yields of sugar and bioethanol. The sequential NaOH and hydroxymethylation pretreatment (AHP) were used to treat sugarcane bagasse (SCB). Compared with NaOH pretreated SCB alone (AP-SCB), AHP increased the yield of glucose and xylose from 53.3%-68.88 %, from 67.8%-74.7 %, respectively. The hydrolysate was fermented using Saccharomyces cerevisiae for 24 h, and then ethanol concentration was 10.67 g/L, which increased by approximately 13 % compared with that of AP-SCB. The post-treatment of hydroxymethylation introduced hydroxymethyl groups and hydroxylic groups into in the aromatic nucleus of lignin, increasing the hydrophilicity and solubility of lignin in materials, which can reduce the nonproductive adsorption of lignin on cellulases and thereby improve the enzymatic saccharification efficiency.