New Method for Quantitative Preparation of Lignin- Carbohydrate Complex from Unbleached Softwood Kraft Pulp: Lignin-Polysaccharide Networks I

Holzforschung ◽  
2003 ◽  
Vol 57 (1) ◽  
pp. 69-74 ◽  
Author(s):  
M. Lawoko ◽  
G. Henriksson ◽  
G. Gellerstedt
Keyword(s):  
Major Part ◽  
Kraft Pulp ◽  
The Other ◽  
Quantitative Yield ◽  
New Method ◽  
Residual Lignin ◽  
Carbohydrate Complex ◽  
Softwood Kraft Pulp ◽  
Minor Part ◽  
A Minor

Summary A new method for the quantitative preparation of pulp representative lignin-carbohydrate complexes (LCC) has been developed, in which LCC has been systematically prepared at quantitative yield, fractionated and qualitatively determined. At least 90% of residual lignin in softwood kraft pulp is proposed to be chemically bonded to carbohydrates. A major part of LCC (92%) in softwood kraft pulp was observed between lignin, xylan and glucomannan, whereas a minor part (8%) was linked to cellulose. Half of the hemicelullosic LCC is a lignin-glucomannan complex. The other half is lignin-xylan complex and xylan-lignin-glucomannan complex. Thus, part of the residual lignin in softwood kraft pulp crosslinks xylan and glucomannan. The proposed linkages are of covalent type. At most 10% of the residual lignin is not bonded covalently to carbohydrates.

Changes in the lignin-carbohydrate complex in softwood kraft pulp during kraft and oxygen delignification

Holzforschung ◽  
2004 ◽  
Vol 58 (6) ◽  
pp. 603-610 ◽  
Author(s):  
Martin Lawoko ◽  
Rickard Berggren ◽  
Fredrik Berthold ◽  
Gunnar Henriksson ◽  
Göran Gellerstedt
Keyword(s):  
Kraft Pulp ◽  
Kappa Number ◽  
Kraft Pulps ◽  
Residual Lignin ◽  
Oxygen Delignification ◽  
Number Range ◽  
Morphological Aspects ◽  
Carbohydrate Complex ◽  
Softwood Kraft Pulp ◽  
Hydrolysis Of

Abstract Three kraft pulps in the kappa number range between 50 and 20 and the same pulps oxygen-delignified to similar lignin contents (kappa approximately 6) were analyzed for lignin-carbohydrate complexes (LCC) by a method based on selective enzymatic hydrolysis of the cellulose, and quantitative fractionation of the LCC. Between 85 and 90% of residual lignin in the unbleached kraft pulp and all residual lignin in the oxygen-delignified pulps were isolated as LCC. Three types of complexes were found; viz., xylan-lignin, glucomannan-lignin-xylan and glucanlignin complexes. After pulping to a high kappa number, most of the residual lignin was linked to xylan. Different delignification rates were observed so that most of the residual lignin was linked to glucomannan when the pulping was extended to a low kappa number. With increasing degree of oxygen delignification, a similar trend in the delignification rates of LCC was observed so that the residual lignin was increasingly linked to glucomannan. Complex LCC network structures seemed to be degraded into simpler structures during delignification. The differences in delignification rates are discussed with reference to the solubility properties and structural differences of LCC, and to morphological aspects of the pulp.

A modified Runge-Kutta method

SIMULATION ◽  
1968 ◽  
Vol 10 (5) ◽  
pp. 221-223 ◽  
Author(s):  
A.S. Chai
Keyword(s):  
Error Estimate ◽  
Linear Combination ◽  
Experimental Results ◽  
The Other ◽  
New Method ◽  
Kutta Method ◽  
Starting Values ◽  
Runge Kutta Method ◽  
Runge Kutta ◽  
A Minor

It is possible to replace k2 in a 4th-order Runge-Kutta for mula (also Nth-order 3 ≤ N ≤ 5) by a linear combination of k1 and the ki's in the last step, using the same procedure for computing the other ki's and y as in the standard R-K method. The advantages of the new method are: It re quires one less derivative evaluation, provides an error estimate at each step, gives more accurate results, and needs a minor change to switch to the RK to obtain the starting values. Experimental results are shown in verification of the for mula.

Isolation of residual lignin from softwood kraft pulp. Advantages of the acetic acid acidolysis method

2004 ◽  
Vol 327 (9-10) ◽  
pp. 911-916 ◽  
Author(s):  
Dominique Lachenal ◽  
Gérard Mortha ◽  
Rose-Marie Sevillano ◽  
Michail Zaroubine
Keyword(s):  
Acetic Acid ◽  
Kraft Pulp ◽  
Residual Lignin ◽  
Softwood Kraft Pulp

Lignin modification in the initial phase of softwood kraft pulp delignification with polyoxometalates (POMs)

Holzforschung ◽  
2007 ◽  
Vol 61 (5) ◽  
pp. 492-498 ◽  
Author(s):  
Biljana Bujanovic ◽  
Sally A. Ralph ◽  
Richard S. Reiner ◽  
Rajai H. Atalla
Keyword(s):  
Kraft Pulp ◽  
Lignin Content ◽  
Kappa Number ◽  
Ring Cleavage ◽  
Residual Lignin ◽  
Glucose Content ◽  
Lower Glucose ◽  
Softwood Kraft Pulp ◽  
Alkaline Conditions ◽  
Extraneous Material

Abstract Commercial softwood kraft pulp with kappa number 30.5 (KP30.5) was delignified with polyoxometalates (POM, Na5(+2)[SiV1(-0.1)MoW10(+0.1)O40]), and POM-treated kraft pulp of kappa number 23.6 was obtained (KPPOM,23.6). Residual lignin from pulps was isolated by mild acid hydrolysis and characterized by analytical and spectral methods to gain insight into lignin reactions taking place during the initial delignification phase. Lignin from POM-delignified pulp was isolated in lower yield. Comparative analysis of residual lignins (RL-KP30.5, RL-KPPOM,23.6) showed that POM leads to products enriched in carbonyl/carboxyl groups and carbohydrates. POM lignins have a lower molecular mass and a lower content of phenolic hydroxyl and methoxyl groups. Based on these results and FTIR spectra, we suggest that aromatic ring cleavage and quinone formation occur during POM delignification. The degree of lignin-cellulose association increases after POM delignification. Lignin-cellulose association was found to be partially unstable under mild alkaline conditions, as residual lignin isolated after alkaline extraction of KPPOM,23.6 pulp (RL-KPPOM/NaOH) exhibited lower glucose content, higher Klason lignin content, and less extraneous material.

Effect of Composition on Shrinkage of Mold Cured Elastomeric Compounds

1978 ◽  
Vol 51 (5) ◽  
pp. 1044-1059 ◽  
Author(s):  
J. R. Beatty
Keyword(s):  
Major Part ◽  
Thermal Coefficient ◽  
Thermal Contraction ◽  
Volume Percent ◽  
Specific Effects ◽  
Degree Of Orientation ◽  
Minor Part ◽  
The Common ◽  
A Minor ◽  
Soft Rubber

Abstract The mold shrinkage of elastomer compositions depends upon the elastomer employed, the volume percent of elastomer plus all other organic materials, and the kind and amount of pigment present. The specific effects of pigments in inhibiting the shrinkage are shown. A procedure is given by which the shrinkage of most soft rubber compositions of the common elastomers may be calculated from the recipe. The major part of the shrinkage of elastomer compositions is due to the much greater thermal contraction of the composition than that of the mold. This portion of the shrinkage depends upon the thermal coefficient of expansion of the composition and mold and the temperature difference between the curing and room temperatures. A minor part of the shrinkage is due to a contraction in volume resulting from vulcanization. For normal soft rubber stocks with sulfur concentrations of three phr or less and for normal neoprene stocks, this factor may be neglected. For stocks having higher sulfur ratios an allowance needs to be made for this factor. Shrinkage of fiber loaded stocks should be determined carefully depending on the quantity, and particularly on the degree of orientation of the processed stock.

STUDY OF SITE GEOMETRY OF THE Sn CATIONS IN THE Sn-ADDED Tl-Pb(1223) SUPERCONDUCTING SYSTEM USING MÖSSBAUER AND AUGER EMISSION TECHNIQUES

1999 ◽  
Vol 13 (23) ◽  
pp. 2887-2893
Author(s):  
KAMLESH KUMARI ◽  
R. K. SINGHAL ◽  
K. B. GARG ◽  
E. M. BAGGIO-SAITOVICH ◽  
SOUZA AZAVEDO ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Major Part ◽  
Mössbauer Spectra ◽  
Mossbauer Spectra ◽  
Doublet Line ◽  
Minor Part ◽  
A Minor ◽  
Tetravalent State ◽  
Weak Doublet

The addition of Sn in Tl,Pb(1223) ( Tl 0.5 Pb 0.5 Sn x Sr 1.6 Ca 2.4 Cu 3 O y) has been investigated using AES and Mössbauer Emission techniques to probe the valence and site geometry of Sn cations. It was found that Sn is present in tetravalent state in the compound at two sites with differing weights. The major part of the tin resides inside the grain and a minor part (weak doublet line in Mossbauer spectra) represents the contribution from the tin at the grain boundary.

scholarly journals Effects of Manganese Peroxidase on Residual Lignin of Softwood Kraft Pulp

1998 ◽  
Vol 64 (6) ◽  
pp. 2273-2274 ◽  
Author(s):  
Ian D. Reid ◽  
Michael G. Paice
Keyword(s):  
Manganese Peroxidase ◽  
Kraft Pulp ◽  
Kappa Number ◽  
Residual Lignin ◽  
Softwood Kraft Pulp

ABSTRACT Manganese peroxidase treatment lowered the kappa number of kraft pulp and increased the alkali extractability of the residual lignin but did not directly solubilize it. This indicates that MnP partially oxidizes the lignin in the pulp but does not degrade it to soluble fragments.

scholarly journals Assessment of Q(OP)D(PO) bleachability of softwood kraft pulp

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sara Starrsjö ◽  
Maria Boman ◽  
Olena Sevastyanova ◽  
Mikael E. Lindström ◽  
Juha Fiskari
Keyword(s):  
Kraft Pulp ◽  
Kappa Number ◽  
Carbohydrate Content ◽  
Residual Lignin ◽  
Three Samples ◽  
Softwood Kraft Pulp ◽  
Pulp Sample ◽  
Yield Gain ◽  
Hexenuronic Acid

Abstract Bleachability is evaluated as how easily a pulp sample is bleached and it depends on the structure of residual lignin and carbohydrates. Also, the bleachability varies depending on the bleaching sequence. ECF light sequences have been improved significantly in the recent years. However, we still don’t fully understand how ECF light bleach plants are optimally run. This work studies the bleachability of softwood kraft pulp in an ECF light bleaching sequence, (OO)Q(OP)D(PO). Three pulp samples with brown stock kappa number 27, 32 and 35 were bleached and studied for residual lignin, hexenuronic acid and carbohydrate content. It was found that in the bleaching stages that are highly delignifying, it is beneficial with a higher kappa number for the delignifying bleachability. However, in the bleaching stages where the objective is brightness increase, the brightness gain bleachability is improved by a lower kappa number. We also intended to determine which of the three samples had the best suited kappa number for this particular bleaching sequence. According to our results, the bleaching was most effective with kappa number around 32. Although an even higher kappa number resulted in higher yield after cooking, it seemed that this bleaching sequence cannot preserve the yield gain.

Effect of lignin content and magnesium-to-manganese ratio on the selectivity of oxygen delignification in softwood kraft pulp

2001 ◽  
Vol 73 (12) ◽  
pp. 2059-2065
Author(s):  
Lucian A. Lucia ◽  
Rachel S. Smereck
Keyword(s):  
Chemical Process ◽  
Kraft Pulp ◽  
Lignin Content ◽  
Dry Mass ◽  
The Other ◽  
Kraft Pulps ◽  
Oxygen Delignification ◽  
Pulp Viscosity ◽  
Softwood Kraft Pulp ◽  
Temperature Time

A series of oxygen delignification experiments were performed on two softwood kraft pulps that had differing starting lignin contents. One had an initial kappa of 40 and the other 25, corresponding to lignin contents of 6% and 3.75% by dry mass, respectively. Several chemical process modifications were examined to determine their influence over the delignification selectivity and final pulp viscosity. A 2k factorial format was used to assess the significance of varying the temperature, time, and Mg/Mn ratio during the oxygen delignification of the pulps. It was found that the lower lignin content pulp displayed greater delignification selectivity than the higher lignin content pulp. Kappa numbers, viscosity values, and ICP metals contents were determined and are the basis of discussion for the results obtained.

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