In:
e-Polymers, Walter de Gruyter GmbH, Vol. 6, No. 1 ( 2006-12-1)
Abstract:
Hemicellulose-type polysaccharides were isolated from the delignified and ultrasonic irradiated sugarcane bagasse by a sequential two-step alkaline extraction. It was found that the successive extractions with 15% and 18% KOH for 2 h, 15% and 18% NaOH for 2 h, 8% and 10% KOH for 15 h, and with 8% and 10% NaOH for 15 h resulted in a total dissolution of 89.6%, 92.8%, 94.9%, and 97.3% of the original hemicelluloses, respectively. Sugar analysis revealed that xylose was the predominant sugar composition of all the hemicelluloses, comprising 57.4- 68.6% of the total sugars. Arabinose (12.3-18.4%) and glucose (10.8- 14.6%) appeared as the second and third major sugar constituents. Galactose (3.9-8.7%), uronic acids, mainly 4- O -methyl-glucuronic acid (2.7-5.8%), rhamnose (1.2-2.6%), and mannose (0.2-1.3%) were observed as minor constituents. The structural studies by 13 C-NMR spectroscopy showed that L-arabino (4- O -methyl-D-glucurono) xylans were the major constituents of the hemicellulosic polymers. Furthermore, the current results also showed that the four alkali-soluble hemicellulosic fractions, isolated during the first step treatment with relatively lower concentrations of alkalis, were more branched and acidic, and had larger molecular weights (M w , 23100-34500), but lower thermal stability than the other four alkali-soluble hemicellulosic preparations (M w , 21700-28700), extracted during the second stage treatment with relatively higher concentrations of alkalis.
Type of Medium:
Online Resource
ISSN:
1618-7229
,
2197-4586
DOI:
10.1515/epoly.2006.6.1.855
Language:
Unknown
Publisher:
Walter de Gruyter GmbH
Publication Date:
2006
detail.hit.zdb_id:
2060396-4
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