title: Structural and thermal characterization of hemicelluloses isolated by organic solvents and alkaline solutions from Tamarix austromongolica.
abstract: Three organosolv and three alkaline hemicellulosic fractions were prepared from lignocellulosic biomass of the fast-growing shrub Tamarix austromongolica (Tamarix Linn.). Sugar analysis revealed that the organosolv-soluble fractions contained a higher content of glucose (33.7-6.5%) and arabinose (14.8-5.6%), and a lower content of xylose (62.2-54.8%) than the hemicellulosic fractions isolated with aqueous alkali solutions. A relatively high concentration of alkali resulted in a decreasing trend of the xylose/4-O-methyl-D-glucuronic acid ratio in the alkali-soluble fractions. The results of NMR analysis supported a major substituted structure based on a linear polymer of β-(1→4)-linked d-xylopyranosyl residues, having ramifications of α-L-arabinofuranose and 4-O-methyl-D-glucuronic acid residues monosubstituted at O-3 and O-2, respectively. Thermogravimetric analysis revealed that one step of major mass loss occurred between 200-400°C, as hemicelluloses devolatilized with total volatile yield of about 55%. It was found that organosolv-soluble fractions are more highly ramified, and showed a higher thermal stability than the alkali-soluble fractions.
authors: Institute of Biomass Chemistry and Technology, Beijing Forestry University, Beijing 100083, China.
authors: Yong-Chang
authors: YC
authors: Sun
authors: Jia-Long
authors: JL
authors: Wen
authors: Feng
authors: F
authors: Xu
authors: Run-Cang
authors: RC
authors: Sun
mesh_terms: D000468:Alkalies / Q000737:chemistry*; D002240:Carbohydrate Sequence; D006358:Hot Temperature; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009930:Organic Chemicals / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry*; D012996:Solutions; D012997:Solvents; D017550:Spectroscopy, Fourier Transform Infrared; D032363:Tamaricaceae / Q000737:chemistry*; D013818:Thermogravimetry
chemical_list: D000468:Alkalies; D009930:Organic Chemicals; D011134:Polysaccharides; D012996:Solutions; D012997:Solvents; C007916:hemicellulose