Fast pyrolysis and enzymatic hydrolysis of bagasse cellulose from synergistic alkaline and oxidative pretreatment

Abstract

Advanced pretreatment technologies can promote comprehensive and effective utilization of native biomass. In this study, cellulose extracted from sugarcane bagasse by synergetic alkaline hydrogen peroxide pretreatment (AHP) was subjected to fast pyrolysis and enzymatic hydrolysis towards the selective production of fermentable sugars, i.e. levoglucosan and glucose. Lignin was effectively removed by an 8 % NaOH solution with trace H2O2, resulting in a 75 % cellulose accumulation in bagasse cellulose. Moreover, the synergetic dissolution and oxidation processes resulted in the ameliorations of lignin-carbohydrate complex structure with effective fiber separation and crystallinity enhancement. Accordingly, fast pyrolysis of bagasse cellulose showed a concentrated thermal decomposition with an overall activation energy enhanced from 236.1 to 246.2 kJ/mol, which could explain the increased levoglucosan content from 3.2 to 60.4 %. In comparison, enzymatic hydrolysis exhibited an enhanced glucose production by 2 times at even low concentration of NaOH using 2 % AHP pretreated bagasse cellulose. This study offers a comparative analysis of the underlying chemistry and kinetic behaviors of biomass saccharification boosted by combined chemical approaches to provoke advanced biorefineries via the “pretreatment–saccharification–fermentation” route.