Efficient ethanol production from masson pine sawdust by various organosolv pretreatment and modified pre-hydrolysis simultaneous saccharification and fermentation

Pretreatment is a key step in lignocellulosic biorefinery. In this study, the combination of organosolv pretreatment and lignin repolymerization inhibitor was put forward to fractionate the lignocellulosic biomass, providing readily hydrolyzed substrate. Results showed that, acidic 1,4-butanediol pretreatment extensively removed lignin from softwood, reducing the physical blockage effect of lignin. Besides, lignin repolymerization inhibitors were employed to modify lignin, giving rise to lower unproductive binding effect of lignin. As a result, maximum 79.9 ± 0.3 % of original lignin in raw biomass could be removed, and 97.9 ± 0.5 % of glucan in pretreated solid could converted into fermentable sugars after acidic butanediol pretreatment assisted by sodium 2-naphthol-7-sulphonate and enzymatic hydrolysis at 2 % glucan loading. Furthermore, a modified pre-hysrolysis simultaneous saccharification and fermentation process at 10 % glucan loading produced 45.6 ± 1.7 g/L ethanol, with ethaol yield of 18.7 ± 0.4 g/100 g raw biomass. Finally, the mass balance revealed that the lignocellulosic biorefinery based on acidic butanediol pretreatment assisted by sodium 2-naphthol-7-sulphonate could achieve full utilization of lignocellulosic components to co-produce ethanol, lignin materials and hemicellulose-derived mono-saccharides.