The integration of different pretreatments and ionic liquid processing of eucalyptus: Hemicellulosic products and regenerated cellulose fibers

The integrated biorefinery of woody biomass for the synthesis of cellulose materials and hemicellulosic products is nowadays considered attractive towards a sustainable standpoint. The effects of alkaline, hydrothermal and acidic pretreatments on the preparation of regenerated cellulose fibers from eucalyptus via ionic liquid wet-spinning, and the isolation and conversion of hemicelluloses using different pretreatments were explored. The structure of alkali-soluble hemicelluloses via 5% sodium hydroxide extraction was deduced to be D-Glcp-4-0-methyl-D-glucurono-o-xylan. The xylooligosaccharides (XOS, DP 2-6) yields by hydrothermal (180 degrees C, 30 min) and 0.25 mol/L dilute sulphric acid (90 degrees C, 1 h) pretreatments were 37.30 and 52.12 mg/g respectively, and the main XOS productions were xylobiose (11.19-15.68 mg/g) and xylotriose (10.03-11.63 mg/g). The isolated cellulose could be completely dissolved in 1-butyl-3-methylimidazolium acetate (IbmimlOAc) and the chemical conformation of the regenerated fibers was similar to cellulose II. The viscosity of the spinning dopes, the morphology. molecular weights and mechanical strength of the fibers were highly dependent on the type of pretreatments. The multifilament fibers exhibited a smooth morphology and good mechanical property (1.55-2.01 cN/dtex) being close to commercial viscose rayon. The conversion of hemicelluloses to value-added products was achieved via different pretreatments in conjugation with cellulose spinning process. (C) 2017 Elsevier B.V. All rights reserved.