Aqueous fractionation of hardwood: selective glucuronoxylan solubilisation and purification of the reaction products

BACKGROUND: The solubilisation of hardwood glucuronoxylan using hot, compressed water is an environmentally friendly technology for biorefineries. Upon processing, most cellulose and lignin remain in the solid phase and can be further separated, enabling the integral benefit of the feedstock. RESULTS: The combined effects of time and temperature on the aqueous, non-isothermal processing of Betula alba wood have been assessed in selected experiments. Operating at temperatures within the range 190-230 degrees C, sugars and higher saccharides derived from glucuronoxylan were the major reaction products, whereas cellulose and lignin were scarcely affected. Refining treatments by membranes and ion-exchange resulted in mixtures of partially acetylated, acidic oligo- and polysaccharides made up of xylose. CONCLUSION: The processing scheme proposed in this work enabled the production of separate streams containing substituted hemicellulosic saccharides with different average polymerisation degrees, which show potential as co-products for biorefineries. (C) 2016 Society of Chemical Industry