Hydrolysis of hemicellulose from barley straw and enhanced enzymatic saccharification of cellulose using acidified zinc chloride

A chemical fractionation process using acidified zinc chloride (ZnCl2) was investigated to recover hemicellulose. The process variables of the fractionation process, including reaction temperature, reaction time, and ZnCl2 concentration, were selected as factors of the experimental design by preliminary tests. The optimal reaction conditions of these three factors for maximal xylose and mannose (XM) recovery yield and purity were determined by statistical experimental design and central composite design (CCD). The determined optimal conditions were 67.9 °C reaction temperature, 10.5 min reaction time, and 7.3% ZnCl2 concentration. The predicted maximum XM recovery yield and purity from the regression equation of dependent variable Y (XM yield) were 47.6% and 75.0% respectively. The experiment showed a 54.5% XM recovery and 72.7% purity under the optimal reaction condition.