Potassium permanganate assisted organosolv pretreatment enhances enzymatic hydrolysis of corn stover

High efficiency enzymatic hydrolysis of lignocellulose to produce fermentable sugar is important for bioconversion of lignocellulosic biomass to liquid fuels and chemicals. In this study, a simple pretreatment with potassium permanganate is used to enhance the efficiency of organosolv pretreatment of corn stover. It is testified that, compared to the single organosolv pretreatment, the KMnO4 assisted organosolv pretreatment significantly increase yields of carbohydrates through decreasing degradation of hemicellulose, decrease formation of inhibitors and enhance enzymatic hydrolysis of corn stover pretreated at a low pretreatment temperature. Process conditions of the KMnO4 assisted organosolv pretreatment are optimized and the conversion of glucan and xylan in pretreated corn stover at 72 h of enzymatic hydrolysis reach to 89.45% and 85.30% respectively when corn stover is firstly treated with 1% (w/w) KMnO4 at 40°C for 60 min prior to ethanol‐water pretreatment with 50% ethanol concentration at 185°C for 90 min. The differences in morphological feature, fiber surface chemical compositions, crystallinity degree and thermostability of pretreated corn stover by ethanol‐water with and without KMnO4 are characterized by scanning electron microscope, X‐ray photoelectron spectroscopy, X‐ray diffraction and thermogravimetry to explore the underlying reasons of KMnO4 strengthening ethanol‐water pretreatment process. Organosolv pretreatment is a promising method for improving enzymatic digestibility of lignocellulose, and ethanol is the frequently used solvent. Generally, ethanol pretreatment is conducted under high temperature for achieving high saccharification efficiency, and serious degradation of hemicellulose occurred during the pretreatment. In this study, we simply used KMnO4 to pretreat corn stover prior to ethanol pretreatment to decrease degradation of hemicellulose and formation of inhibitors, as well as enhance enzymatic hydrolysis of corn stover at a low pretreatment temperature. The findings are valuable for developing a low‐cost and effective ethanol pretreatment method and obtaining high yield fermentable sugars.