Efficient extraction and characterization of polymeric hemicelluloses from hybrid poplar (original) (raw)
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Polymers
In this study, hemicelluloses of aspen wood (Pópulus trémula) were obtained by oxidative delignification in an acetic acid-water-hydrogen peroxide medium at temperatures of 70–100 °C and a process time of 1–4 h. The maximum polysaccharide yield of up to 9.68 wt% was reported. The composition and structure of the hemicelluloses were studied using a complex of physicochemical methods: gas and gel permeation chromatography, Fourier-transform infrared spectroscopy, 2D nuclear magnetic resonance spectroscopy, and thermogravimetric analysis. The xylose, mannose, galactose, and glucose monomer units were identified in the hemicelluloses by gas chromatography. The weight average molecular weight Mw of the products determined by gel permeation chromatography was found to range within 8932–33,142 g/mol. The reported Fourier-transform spectra of the hemicelluloses contain all the bands characteristic of heteropolysaccharides; a weak lignin absorption signal in the spectra at 1500–1510 cm−1 is ...
Physicochemical characterization of hemicelluloses from bamboo (Phyllostachys pubescens Mazel) stem
Industrial Crops and Products, 2012
In this paper, hemicelluloses from bamboo (Phyllostachys pubescens Mazel) stem aged six months were sequentially extracted with hot water, 2% KOH, and 5% NaOH. The water-soluble hemicelluloses H 1 , and four alkali-soluble hemicellulosic fractions H 2 , H 3 , H 4 and H 5 were obtained, achieving a total yield of 59.60% based on the original hemicelluloses. Sugar composition analysis showed that the hemicelluloses were mainly composed of xylose (44.39-72.71%), arabinose (26.36-51.87%), ribose (0.93-2.72%), and uronic acid (0.29-5.27%). The structures of the hemicelluloses were determined to be mainly arabinoxylan, using the FT-IR and NMR techniques. The AFM images of fraction H 3 revealed a distribution of spherical nanoparticles with different sizes, while the fraction H 2 had helix rod and random coil feature. The SEM characterizations indicated that the fraction H 1 displayed spherical particles while the fraction H 3 had mainly flat particles at high magnification. Thermal stability was also analyzed using TG-DTG method and first-order kinetics model.
Characteristics of the Water-and Alkali-Soluble Hemicelluloses Fractionated by Sequential.pdf
Sweet maize stems were treated with hot water and potassium hydroxide to fractionate hemicellulosic polymers. The results showed that the water-soluble hemicelluloses were mainly composed of glucose (27.83%), xylose (27.32%), and galactose (16.81%). In comparison, alkali-soluble hemicelluloses fractionated by acidification and a graded ethanol solution (10%, 20%, 35%, 50%, 65%, and 80%) were mainly composed of xylose (69.73 to 88.62%) and arabinose (5.41 to 16.20%). More highly branched hemicelluloses tended to be precipitated in a higher concentration of ethanol solution, as revealed by the decreasing xylose to arabinose ratio from 16.43 to 4.21. Structural characterizations indicated that alkali-soluble hemicelluloses fractionated from sweet maize stems were mainly arabinoxylans. The results provided fundamental information on hemicelluloses composition and structure and their potential utilization in the fields of biofuels, biochemicals, and biomaterials.
Food and Bioproducts Processing, 2020
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Extraction and Utilization of Hemicelluloses for New Biomaterial Applications
Hemicellulose material is an abundant, relatively under-utilized polymeric material present in lignocellulosic materials. In this research, an alkaline treatment was applied to wood and grasses in order to extract hemicelluloses to subsequently produce novel materials. An extraction at 75°C recovered 23% of the biomass as a predominantly hemicellulose material with a number average degree of polymerization of ~ 450 determined by gel permeation chromatography. These hemicelluloses were modified separately with different agents (monomers, polymers) such as citric acid, succinic anhydride, sodium monochloracetate and chitosan for improved absorbency applications. This report also describes the use of an ionic liquid to acetylate hemicellulose without the need of a catalyst as reactive solvents for their eco-friendliness (green application) enhanced thermal stability and higher reaction rates for hemicelluloses modified. The new products were characterized by FTIR spectroscopy, Nuclear Magnetic Resonance, thermal properties analysis, saline absorbency and surface area analysis. The results obtained indicate promising combinations between the effective extraction of hemicellulose from different biomass and environmentally friendly processes to generate the next generation of hemicellulose modified with high degree of polymerization for use in various industrial applications.
Isolation and characterisation of hemicelluloses from sunflower hulls
Carbohydrate Research, 1993
The hemicelluloses extracted from sunflower hulls by repeated alternating oxidative and alkaline treatments were purified by precipitation with Cetavlon and then ion-exchange chromatography on DEAE-trisacryl. The resulting fractions were examined by hydrolysis, methylation, GLC-MS, and NMR spectroscopy. The hemicelluloses are of the glucuronoxylan type with the following structure 4 4)-p-D-Xylp-(1-t 4)[4-O-Me-aD -GlcpA-(1 + 2)]-p-D-Xylp-(1 +. The polysaccharides differed in the amount of branching; the ratio of the main fraction 40MeGlcA : Xyl was 1: 8-9.
Bioresource Technology, 2018
Formic acid/water binary solvent extraction with formic acid fraction lower than 77.5% (w/w) of azeotrope was used to extract hemicellulose-derived saccharides from poplar wood at various levels of severity. The highest xylose yield of 77.8% and arabinose yield of 93.5% were obtained at 120°C and 1 h. To reduce cellulose hydrolysis and facilitate downstream xylose crystallization, mild conditions at 90°C and 4 h was chosen as optimum severity, which led to the highest xylose fraction of 81.7% in all saccharides extracted, with a remarkable xylose yield of 73.1%. Mass balance analysis showed that 5.84% of xylan was degraded, but only 0.25% of xylan ended up as furfural at optimum severity. The proposed extraction process has high feasibility for industrial application since the low formic acid fraction in solvent allows simple recovery and concentration of used solvent.
Water-soluble hemicelluloses and eight alkali-soluble hemicelluloses were fractionated from bamboo (Phyllostachys pubescens Mazel) culm with hot distilled water, 2% NaOH, 2% KOH, 5% NaOH, and 5% KOH aqueous solution. The chemical structures, as analyzed employing FTIR spectrometry, suggested that all the hemicelluloses were likely to be comprised of arabinoxylans associated with lignin more or less. Thermal analysis for hemicelluloses was carried out using TG-DTG method under nitrogen atmosphere at a heating rate of 10 C/min, and first-order kinetics was evaluated. The major pyrolysis was focused at 187-346 C, with activation energy ranging from 23.77 to 45.02 kJ/mol. The alkalisoluble fractions, being soluble in solution only at pH higher than 5.5, presented lower thermal stability and higher values of activation energy and pre-exponential factor than the alkali-soluble fractions remaining soluble in alkaline solution at pH lower than 5.5 and insoluble in ethanol. The chemical property of the hemicellulose fractions may greatly influence the thermal characteristics.
Extraction of hemicelluloses from fiberized spruce wood
Carbohydrate Polymers, 2015
A novel mechanical pre-treatment method was used to separate the wood chips into fiber bundles in order to extract high molecular weight wood polymers. The mechanical pre-treatment involved chip compression in a conical plug-screw followed by defibration in a fiberizer. The fiberized wood was treated with hot water at various combinations of time and temperature in order to analyze the extraction yield of hemicelluloses at different conditions. Nearly 6 mg/g wood of galactoglucomannan was obtained at 90 • C/120 min which was about three times more than what could be extracted from wood chips. The extracted carbohydrates had molecular weight ranging up to 60 kDa. About 10% of each of the extracted material had a molecular weight above 30 kDa. The extraction liquor could also be reused for consecutive extractions with successive increase in the extraction yield of hemicelluloses.