Characteristics of degraded cellulose obtained from steam-exploded wheat straw.
The isolation of cellulose from wheat straw was studied using a two-stage process based on steam explosion pre-treatment followed by alkaline peroxide post-treatment. Straw was steamed at 200 degrees C, 15 bar for 10 and 33 min, and 220 degrees C, 22 bar for 3, 5 and 8 min with a solid to liquid ratio of 2:1 (w/w) and 220 degrees C, 22 bar for 5 min with a solid to liquid ratio of 10:1, respectively. The steamed straw was washed with hot water to yield a solution rich in hemicelluloses-derived mono- and oligosaccharides and gave 61.3%, 60.2%, 66.2%, 63.1%, 60.3% and 61.3% of the straw residue, respectively. The washed fibre was delignified and bleached by 2% H2O2 at 50 degrees C for 5 h under pH 11.5, which yielded 34.9%, 32.6%, 40.0%, 36.9%, 30.9% and 36.1% (% dry wheat straw) of the cellulose preparation, respectively. The optimum cellulose yield (40.0%) was obtained when the steam explosion pre-treatment was performed at 220 degrees C, 22 bar for 3 min with a solid to liquid ratio of 2:1, in which the cellulose fraction obtained had a viscosity average degree of polymerisation of 587 and contained 14.6% hemicelluloses and 1.2% klason lignin. The steam explosion pre-treatment led to a significant loss in hemicelluloses and alkaline peroxide post-treatment resulted in substantial dissolution of lignin and an increase in cellulose crystallinity. The six isolated cellulose samples were further characterised by FT-IR and 13C-CP/MAS NMR spectroscopy and thermal analysis.
Sun
X F
XF
College of Forestry, The North-Western University of Agricultural and Forest Sciences and Technology, Yangling 712100, China.
Xu
F
F
Sun
R C
RC
Fowler
P
P
Baird
M S
MS
D002482:Cellulose / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D008031:Lignin / Q000032:analysis / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D018547:Plant Stems / Q000737:chemistry* / Q000378:metabolism; D011134:Polysaccharides / Q000032:analysis / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013227:Steam; D013816:Thermodynamics; D014908:Triticum / Q000737:chemistry* / Q000378:metabolism
D011134:Polysaccharides; D013227:Steam; C007916:hemicellulose; D002482:Cellulose; D008031:Lignin