The recalcitrant structure of corn stover hinders its high value utilization.In this study,a freeze-thaw assisted ultra-low acid pretreatment method is proposed to selectively remove hemicellulose.The selective removal of hemicellulose from stover was achieved by ultra-low concentration of sulfuric acid,and the freeze-thawing action broke the cellulose hydrogen bonds and reduced the crystallinity of stover cellulose,which further improved the glucose yield of cellulolytic enzymes.The results showed,that the optimal pretreatment conditions were-20℃ freezing for 12 h,0.1% sulfuric acid treatment at 180℃ for 30 min,the hemicellulose removal rate could reach 93.93%,and the enzymatic glucose yield reached 94.11% .Characterization analyses revealed that the pretreated straw structure was destroyed,roughness increased and specific surface area increased,which could effectively increase the cellulase accessibility and improve the enzymatic efficiency.This study provides new ideas for achieving selective separation and efficient conversion of lignocellulose.
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