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.

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.

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.

Eucalyptus globulus Kraft Pulp Residual Lignins. Part 1. Effects of Extraction Methods upon Lignin Structure

Holzforschung ◽  
2000 ◽  
Vol 54 (4) ◽  
pp. 365-372 ◽  
Author(s):  
Ana Paula Duarte ◽  
Danielle Robert ◽  
Dominique Lachenal
Keyword(s):  
Enzymatic Hydrolysis ◽  
Acid Hydrolysis ◽  
Eucalyptus Globulus ◽  
Kraft Pulp ◽  
Extraction Methods ◽  
Extraction Yield ◽  
Residual Lignin ◽  
Softwood Kraft Pulp ◽  
Ft Ir ◽  
Hydrolysis Conditions

Summary Residual lignins of Eucalyptus globulus kraft pulp were shown to be structurally different depending upon the type of extraction chosen. Enzymatic hydrolysis releases a residual lignin with a well preserved etherified structure but substantially contaminated by protein and carbohydrate moieties coming from the enzyme. Moreover, the extraction yield is poor and obviously it does not work as well as in the case of softwood kraft pulp. The residual lignin extracted by acid hydrolysis has less etherified units and more free phenolic functions than that of the enzymatic hydrolysis. It contains some unsaturated structures but no carbohydrate contaminants. Comparison with Milled Wood Lignin (MWL) treated under the acid hydrolysis conditions shows that ether splitting occurs during this extraction. The different residual lignin fractions were characterised by HPSEC, FT-IR, 13C NMR and sugar analysis.

scholarly journals Factors limiting oxygen delignification of kraft pulp

2001 ◽  
Vol 79 (2) ◽  
pp. 201-210 ◽  
Author(s):  
Leonid G Akim ◽  
Jorge Luiz Colodette ◽  
Dimitris S Argyropoulos
Keyword(s):  
Kraft Pulp ◽  
Oxidation Mechanism ◽  
Quantitative Information ◽  
Total Phenolic ◽  
Residual Lignin ◽  
Analytical Pyrolysis ◽  
Oxygen Delignification ◽  
Softwood Kraft Pulp ◽  
Major Factors ◽  
C Nmr

Softwood kraft pulp was subjected to a laboratory one- and three-stage oxygen delignification process. Pulp and liquor samples were collected at different stages of the process with particular attention being paid to the early and late stages. A novel residual lignin isolation method extracted about 65% of the oxidized residual lignins at a purity exceeding 90%. Using this methodology coupled to quantitative 31P NMR, 13C NMR, 2D heteronuclear (HMQC) NMR spectroscopic and analytical pyrolysis techniques allowed a thorough characterization of the residual and solubilized lignin fractions at the various stages of the process. Our conclusions do not point to a single factor as being responsible for the limits confronting oxygen delignification. Amongst the major factors impeding the effectiveness of oxygen delignification are: (i) the accumulation of relatively inert 5,5' biphenyl structures originally present in kraft lignin from dibenzodioxocin ring opening reactions; and (ii) the accumulation of considerably less reactive p-hydroxyphenyl structures. Detailed quantitative information was obtained and discussed in relation to the presence and role of these unreactive phenolic fractions on the residual oxidized lignins. As such we arrived at important conclusions as to why and how these structures remain and accumulate on the fiber. In addition, issues related to the profiles of the total phenolic hydroxyl content of the residual lignins and the remaining arylglycerol β-O-4 structures are discussed.Key words: analytical pyrolysis, biphenyl structures, HMQC, NMR, oxidation mechanism, oxygen delignification, p-hydroxyphenyl moieties, quantitative 13C NMR, quantitative 31P NMR, residual lignin, solubilized lignin, total phenolic hydroxyls.

Elucidating carboxylic acid profiles for extended oxygen delignification of high-kappa softwood kraft pulps

Holzforschung ◽  
2006 ◽  
Vol 60 (2) ◽  
pp. 123-129 ◽  
Author(s):  
Dongcheng Zhang ◽  
Yunqiao Pu ◽  
Xing-Sheng Chai ◽  
Ved Naithani ◽  
Hasan Jameel ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Acid Content ◽  
Kraft Pulp ◽  
Lignin Content ◽  
Acid Group ◽  
Kraft Pulps ◽  
Residual Lignin ◽  
Oxygen Delignification ◽  
Acid Ratio ◽  
Softwood Kraft Pulp

Abstract Two laboratory high-lignin-content softwood (SW) kraft pulps with kappa values of 48.0 and 49.5, prepared by cooking at high and low active alkali (AA), were used for the study of fiber charge development during two-stage oxygen delignification with inter-stage washing (OwO). It was established that the first oxygen delignification (O) stage increased total fiber charge by 2–4%, and further O-delignification via a second O-stage led to a 3–18% decrease in total fiber charge. Carboxylic acid content in pulp holocelluloses decreased by 12–26% with respect to a 35–70% kappa number reduction due to an O and OwO stage of delignification for high and low AA cooked SW kraft pulps. After an OwO-stage delignification, the residual lignin was found to exhibit a 50–100% increase in carboxylic acid content. 13C NMR spectral data for the residual lignin samples indicated that the unconjugated/conjugated acid ratio was approximately (3–4):1. Generally, the carboxylic acid content in low AA cooked softwood kraft pulp and the corresponding oxygen-delignified pulps was systematically higher (13–23%) than that in high AA cooked SW kraft pulp and the corresponding oxygen-delignified pulps. The experimental results also demonstrated that maximum acid-group content in total fiber occurred after 45–50% oxygen delignification of the SW kraft pulps studied.

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.

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