Integrated chemical and multi-scale structural analyses for the processes of acid pretreatment and enzymatic hydrolysis of corn stover

•Both acid pretreatment (AP) and enzymolysis (EL) of corn stover were characterized.•AP decreased hemicellulose from 19.7% in raw substrate to 9.28%.•AP increased pore volume from 0.0067 cm3/g in raw substrate to 0.019 cm3/g.•Enzyme adsorption in AP substrate was three-fold higher than that in raw substrate.•EL proceeded in the parallel hydrolysis mode of crystalline/amorphous cellulose.

Corn stover was pretreated with acid under moderate conditions (1.5%, w/w, 121 °C, 60 min), and kinetic enzymolysis experiments were performed on the pretreated substrate using a mixture of Celluclast 1.5 L (20 FPU/g dry substrate) and Novozyme 188 (40 CBU/g dry substrate). Integrated chemical and multi-scale structural methods were then used to characterize both processes. Chemical analysis showed that acid pretreatment removed considerable hemicellulose (from 19.7% in native substrate to 9.28% in acid-pretreated substrate) and achieved a reasonably high conversion efficiency (58.63% of glucose yield) in the subsequent enzymatic hydrolysis. Multi-scale structural analysis indicated that acid pretreatment caused structural changes via cleaving acetyl linkages, solubilizing hemicellulose, relocating cell wall surfaces and enlarging substrate porosity (pore volume increased from 0.0067 cm3/g in native substrate to 0.019 cm3/g in acid-pretreated substrate), thereby improving the polysaccharide digestibility.

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