Production of Xylooligosaccharides from Waste Xylan, Obtained from Viscose Fiber Processing, by Selective Hydrolysis Using Concentrated Acetic Acid

Xylooligosaccharides (XOS) were prepared by selective hydrolysis of the waste xylan, obtained from viscose fiber plants, using concentrated acetic acid. The influences of acetic acid concentration, reaction temperature, and reaction time on the yield and component profiles of XOS product were investigated. These results were further ascertained by designing orthogonal experiments. The hydrolysis of xylan residue was selective, since mainly xylooligosaccharide components were formed, with hardly any impure ingredients, except for a small amount of xylose and traces of furfural, in the hydrolyzed product. Reaction temperature was found to be the most significant factor, influencing the XOS yield. Accurate HPAEC-PAD analysis of component profiles indicated that a maximum XOS yield of 45.86% was achieved on hydrolysis of 33.77g/L waste xylan using 20% acetic acid for 20min at 140 degrees C. The main XOS components obtained were xylobiose, xylotriose, and xylotetraose, which were more than xylopentaose and xylohexaose.