Physicochemical characterisation of residual hemicelluloses isolated with cyanamide-activated hydrogen peroxide from organosolv pre-treated wheat straw.
Seven residual hemicellulosic preparations (19.6-45.0% of the original hemicelluloses) were extracted from wheat straw pre-treated with various organic solvents using 1.8% H2O2-0.18% cyanamide at 50 degrees C and pH 10.0 for 4 h. Their chemical compositions and physicochemical properties were determined using GC, HPLC, GPC, FT-IR and 13NMR spectroscopy. The results indicated that all the residual hemicellulosic preparations were heteropolysaccharides containing xylose, glucose, arabinose, galactose, mannose, rhamnose and 4-O-methyl-alpha-D-glucopyranosyluronic acid. The predominant monosaccharide was xylose, ranging between 67.7% and 81.9% of the total neutral sugars, composed mainly of L-arabino-(4-O-methyl-D-glucurono)-D-xylan. The content of contaminant lignin in the isolated residual hemicelluloses was 2.89-5.31%. The Mw values of the two residual hemicellulosic preparations H6 and H7 (42,710 and 44,080 g mol-1, respectively) obtained from the aqueous-alcohol pre-treated straw were much higher than those of H1-H5 (12,980-15,950 g mol-1) extracted from the organic acid pre-treated straw.
Sun
Xiao Feng
XF
College of Forestry, The North-Western University of Agricultural and Forest Sciences and Technology, Yangling 712100, China.
Xu
F
F
Zhao
H
H
Sun
R C
RC
Fowler
P
P
Baird
M S
MS
D002241:Carbohydrates / Q000737:chemistry; D005591:Chemical Fractionation; D003484:Cyanamide / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D008031:Lignin / Q000737:chemistry; D018547:Plant Stems / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry* / Q000302:isolation & purification; D012037:Refuse Disposal / Q000379:methods; D012997:Solvents; D014908:Triticum / Q000737:chemistry*
D002241:Carbohydrates; D011108:Polymers; D011134:Polysaccharides; D012997:Solvents; D003484:Cyanamide; C007916:hemicellulose; D008031:Lignin; D006861:Hydrogen Peroxide