Preliminary exploration on pretreatment with metal chlorides and enzymatic hydrolysis of bagasse

• Bagasse was pretreated with metal chlorides for bio-conversion.
• Hemicelluloses could be efficiently removed by metal chlorides to promote CED.
• Metal chlorides with low pKa values facilitated degradation of bagasse.
• An inhibition factor was proposed to describe cellulase digestibility of biomass.
• The enzymatic digestibility of bagasse pretreated with FeCl3 approached to 100%.

Converting biomass to fermentable sugar is the critical step in the biomass refinery. Moreover, pretreatment of biomass plays an important role in improving the conversion of biomass to sugar. In this study, sugarcane bagasse was pretreated by metal chloride Lewis acids (0.1 mol L−3 CrCl3, FeCl3, FeCl2, ZnCl2 and AlCl3 solution) for cellulase hydrolysis. The effects of pretreatments on the yield, chemical components, and sequential cellulase hydrolysis of pretreated bagasse were investigated. The results indicated that metal chlorides with different pKa values could efficiently remove the hemicellulose in bagasse during pretreatment. Furthermore, an inhibition factor (IF) quantitatively reflecting difficulty of cellulase hydrolysis was proposed. The low IF means the facile cellulase hydrolysis. The IF of Fe (III)-pretreated bagasse could decrease to 1.35. In this case, the enzymatic digestibility of bagasse approached to 100%.

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