Behavior of xylans from Eucalyptus species. Part 1. The influence of structural features of eucalyptus xylans on their retention in kraft pulp

Holzforschung ◽  
2013 ◽  
Vol 67 (2) ◽  
pp. 115-122 ◽  
Author(s):  
Andréia S. Magaton ◽  
Teresa Cristina F. Silva ◽  
Jorge Luiz Colodette ◽  
Dorila Piló-Veloso ◽  
Flaviana Reis Milagres
Keyword(s):  
Average Molecular Weight ◽  
Structural Features ◽  
Kraft Pulping ◽  
Size Exclusion ◽  
Pulp Yield ◽  
Eucalyptus Species ◽  
H Nmr ◽  
Uronic Acid Content ◽  
Exclusion Chromatography ◽  
Hexenuronic Acid

Abstract 4-O-methylglucuronoxylans were isolated from the wood and pulp of different Eucalyptus species (E. dunni, E. grandis, E. nitens, E. urograndis and E. urophylla) and characterized by 1H NMR spectroscopy and size-exclusion chromatography (SEC). The content of 4-O-methylglucuronic acid (MeGlcA) varied between the eucalyptus species from 1.90 to 2.80 expressed as MeGlcA/10 xyloses, whereas in the pulp, the total uronic acid content was approximately 1.02, from which the half was hexenuronic acid (HexA). From the MeGlcA linked to the xylan chain 9–26% are substituted in position O-2 by hexose units. The Mw of the xylans extracted from wood ranged between 26.1 and 28.4 kDa. The retention of 4-O-methylglucuronoxylans (51.3–58.7%) during kraft pulping was high, and the retention is related to the content of MeGlcA group, the content of MeGlcA group substituted at O-2, and the average molecular weight of the xylans. The parameters observed affect the overall pulp yield and pulp properties.

Behavior of xylans from the Eucalyptus species. Part 2. Characterization of 4-O-methylglucuronoxylans isolated from black liquors of kraft pulping of Eucalyptus grandis and E. urophylla

Holzforschung ◽  
2013 ◽  
Vol 67 (2) ◽  
pp. 123-128
Author(s):  
Andréia S. Magaton ◽  
Teresa Cristina F. Silva ◽  
Jorge Luiz Colodette ◽  
Dorila Piló-Veloso ◽  
Flaviana Reis Milagres ◽  
...  
Keyword(s):  
Average Molecular Weight ◽  
Eucalyptus Grandis ◽  
Kraft Pulping ◽  
Raw Material ◽  
Size Exclusion ◽  
Eucalyptus Species ◽  
Exclusion Chromatography ◽  
Ft Ir ◽  
Black Liquors

Abstract 4-O-methylglucuronoxylans isolated from Eucalyptus grandis and Eucalyptus urophylla kraft black liquors (KBLs) were chemically characterized by Fourier transform infrared spectroscopy (FT-IR), size exclusion chromatography (SEC), and nuclear magnetic resonance (NMR) spectroscopy. Doses of alkali charge, expressed as active alkali (AA), were 16, 17, and 18% while the sulfidity was kept at 25%. Kappa numbers of 19.1, 17.5, and 16.1 for E. grandis and 20.4, 16.8, and 15.4 for E. urophylla were obtained. At higher alkali charges, the recovery of xylans from the KBLs was lower and the degree of substitution of xylans with uronic acids decreased. The average molecular weight (Mw) of the recovered xylans was greater under conditions of mild pulping, i.e., in the case of pulps with higher kappa numbers. Mw of xylans ranged from 16.1 to 19.1 kDa for E. grandis and from 15.4 to 20.4 kDa for E. urophylla. The xylans from KBL may be useful as pulp modifying agents or as a raw material for advanced applications.

Structure of a shear-thickening polysaccharide extracted from the New Zealand black tree fern, Cyathea medullaris

2020 ◽  
Author(s):  
M Wee ◽  
M Mastrangelo ◽  
Susan Carnachan ◽  
Ian Sims ◽  
K Goh
Keyword(s):  
New Zealand ◽  
Uronic Acid ◽  
Average Molecular Weight ◽  
Shear Thickening ◽  
Water Soluble ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Tree Fern ◽  
13C Nuclear Magnetic Resonance ◽  
Exclusion Chromatography

A shear-thickening water-soluble polysaccharide was purified from mucilage extracted from the fronds of the New Zealand black tree fern (Cyathea medullaris or 'mamaku' in Māori) and its structure characterised. Constituent sugar analysis by three complementary methods, combined with linkage analysis (of carboxyl reduced samples) and 1H and 13C nuclear magnetic resonance spectroscopy (NMR) revealed a glucuronomannan comprising a backbone of 4-linked methylesterified glucopyranosyl uronic acid and 2-linked mannopyranosyl residues, branched at O-3 of 45% and at both O-3 and O-4 of 53% of the mannopyranosyl residues with side chains likely comprising terminal xylopyranosyl, terminal galactopyranosyl, non-methylesterified terminal glucopyranosyl uronic acid and 3-linked glucopyranosyl uronic acid residues. The weight-average molecular weight of the purified polysaccharide was ~1.9×106Da as determined by size-exclusion chromatography coupled with multi-angle laser light scattering (SEC-MALLS). The distinctive rheological properties of this polysaccharide are discussed in relation to its structure. © 2014 Elsevier B.V.

High Performance Size Exclusion Chromatograph with Computerized Data Reduction for Analysis of Polyethylene and Oligomers

1981 ◽  
Vol 64 (4) ◽  
pp. 999-1007
Author(s):  
Roger C Snyder ◽  
Charles V Breder
Keyword(s):  
Molecular Weight ◽  
High Performance ◽  
Average Molecular Weight ◽  
Porous Silica ◽  
Size Exclusion ◽  
Dead Volume ◽  
Shape Distortion ◽  
Molecular Weight Range ◽  
Liquid Chromatograph ◽  
Exclusion Chromatography

Abstract A liquid chromatograph is described for the size exclusion chromatography (SEC) of polyethylene and oligomers. The rigid column packing material was 10 µm diameter porous silica. An infrared spectrophotometer was used as the detector. The chromatograph was designed and operated to minimize the degree of chromatographic peak shape distortion resulting from factors such as system dead volume, detector cell design, sample injection volume, and sample concentration. To compensate for peak spreading and skewing, the chromatographic data were analyzed with an IBM 370/168 computer using an APL program. The molecular weight range covered by this SEC system was 100-500 000. Precision and accuracy of Jhe calculated weight average molecular weight (Mw) values for polyethylene standards over this range were ±3 and s±4%, respectively.

scholarly journals Enzymatic Fibre Modification During Production of Dissolving Wood Pulp for Regenerated Cellulosic Materials

2021 ◽  
Vol 12 ◽  
Author(s):  
Pedro E. G. Loureiro ◽  
Sonia M. S. Cadete ◽  
Radina Tokin ◽  
Dmitry V. Evtuguin ◽  
Henrik Lund ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Wood Pulp ◽  
Kraft Pulping ◽  
Dissolving Pulp ◽  
Raw Material ◽  
Pulp Yield ◽  
Polysaccharide Monooxygenases ◽  
Cold Caustic Extraction ◽  
Cellulosic Fibres

The production of regenerated cellulosic fibres, such as viscose, modal and lyocell, is based mainly on the use of dissolving wood pulp as raw material. Enzymatic processes are an excellent alternative to conventional chemical routes in the production of dissolving pulp, in terms of energy efficiency, reagent consumption and pulp yield. The two main characteristics of a dissolving pulp are the cellulose purity and the molecular weight, both of which can be controlled with the aid of enzymes. A purification process for paper-grade kraft pulp has been proposed, based on the use of xylanases in combination with hot and cold caustic extraction, without the conventional pre-hydrolysis step before kraft pulping. This enzyme aided purification allowed the production of a dissolving pulp that met the specifications for the manufacture of viscose, < 3% xylan, > 92% ISO brightness and 70% Fock’s reactivity. Endoglucanases (EGs) can efficiently reduce the average molecular weight of the cellulose while simultaneously increasing the pulp reactivity for viscose production. It is shown in this study that lytic polysaccharide monooxygenases act synergistically with EGs in the modification of bleached dissolving pulp.

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