Oxygen Delignification of High-Yield Kraft Pulp. Part I: Structural Properties of Residual Lignins

Holzforschung ◽  
1999 ◽  
Vol 53 (4) ◽  
pp. 416-422 ◽  
Author(s):  
Størker T. Moe ◽  
Arthur J. Ragauskas
Keyword(s):  
Carboxylic Acid ◽  
Acid Hydrolysis ◽  
Extraction Method ◽  
Kraft Pulp ◽  
Kraft Pulping ◽  
High Yield ◽  
Kraft Pulps ◽  
Residual Lignin ◽  
Oxygen Delignification ◽  
Carboxylic Acid Groups

Summary The chemistry of oxygen delignification of high-yield kraft pulp was studied by analysis of residual lignin extracted from kraft and kraft-oxygen pulps using the acid hydrolysis/dioxane extraction method. For reference pulps cooked to kappa numbers between 20 and 25, the content of free phenolic groups decreased to about 50% the original value upon oxygen delignification, while the content of carboxylic acid groups increased by 50–100%. For lignins isolated from high-yield kraft pulp and oxygen delignified high-yield kraft pulp, it was shown that high-yield kraft pulping with polysulfide (PS) and anthraquinone (AQ) gives a residual lignin which is chemically different from that of kraft pulps cooked to lower kappa numbers. Lignin extracted from oxygen delignified high-yield PS/AQ kraft pulp was more similar to lignins extracted from kraft pulps cooked to lower kappa numbers.

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.

Evidence for the formation of lignin-hexenuronic acid-xylan complexes during modified kraft pulping processes

Holzforschung ◽  
2006 ◽  
Vol 60 (2) ◽  
pp. 137-142 ◽  
Author(s):  
Zhi-Hua Jiang ◽  
Jean Bouchard ◽  
Richard Berry
Keyword(s):  
Acid Hydrolysis ◽  
Kraft Pulp ◽  
Kraft Pulping ◽  
Order Kinetic ◽  
Kraft Pulps ◽  
First Order ◽  
Pseudo First Order ◽  
Hexenuronic Acid ◽  
Kinetics Of ◽  
Hydrolysis Of

Abstract The finding that hexenuronic acid (HexA) groups can be selectively removed from kraft pulps by acid hydrolysis has provided an opportunity to reduce bleaching chemicals. However, there is evidence that the acid hydrolysis is not uniform. In this report, we evaluate the kinetics of acid hydrolysis of HexA in a xylan sample enriched with HexA, a conventional kraft pulp, and three modified kraft pulps: anthraquinone pulp (Kraft-AQ), polysulfide pulp (PS), and polysulfide-anthraquinone pulp (PS-AQ). We found that HexA present in the xylan and conventional kraft pulp behaved similarly toward the acid hydrolysis throughout. On the other hand, HexA present in the Kraft-AQ, PS-AQ and PS pulps was heterogeneous toward acid hydrolysis and the reaction can be separated into two pseudo-first-order kinetic phases, each of which has a different rate constant. The kinetic data provide evidence for the formation of lignin-HexA-xylan complexes during modified kraft pulping processes.

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.

Eucalyptus globulus Kraft Pulp Residual Lignin. Part 2. Modification of Residual Lignin Structure in Oxygen Bleaching

Holzforschung ◽  
2001 ◽  
Vol 55 (6) ◽  
pp. 645-651 ◽  
Author(s):  
A.P. Duarte ◽  
D. Robert ◽  
D. Lachenal
Keyword(s):  
Acid Hydrolysis ◽  
Structural Changes ◽  
Kraft Pulping ◽  
Kraft Pulps ◽  
Residual Lignin ◽  
Qualitative And Quantitative ◽  
Methylene Groups ◽  
Hydrolysis Conditions ◽  
C Nmr ◽  
Oxygen Bleaching

Summary Residual lignins were isolated from unbleached and oxygen-bleached Eucalyptus kraft pulps by acid hydrolysis. The structural changes and degradation of residual lignin occurring during kraft pulping and oxygen bleaching were followed and identified by elemental analysis, residual carbohydrate analysis, molecular mass distribution, as well as qualitative and quantitative solution 13C NMR. The dissolved lignins in the kraft cooked and oxygen bleached liquors were also studied and compared with the corresponding residual lignins. Milled wood lignin treated under acid hydrolysis conditions served as a reference for the structural comparison. The results show that etherified syringyl structures were quite resistant towards degradation in the oxygen bleaching, causing little depolymerisation in residual lignin and a small increase in carboxylic acid content, but producing appreciable amounts of saturated aliphatic methylene groups.

Bleaching ability of pre-hydrolyzed pulps in the context of a biorefinery mill

TAPPI Journal ◽  
2013 ◽  
Vol 12 (11) ◽  
pp. 49-53 ◽  
Author(s):  
CHRISTINE CHIRAT ◽  
LUCIE BOIRON ◽  
DOMINIQUE LACHENAL
Keyword(s):  
Carbon Content ◽  
Acid Hydrolysis ◽  
13C Nmr ◽  
Kraft Lignin ◽  
Kappa Number ◽  
Hydroxyl Groups ◽  
Kraft Pulps ◽  
Quaternary Carbon ◽  
Oxygen Delignification

Autohydrolysis and acid hydrolysis treatments were applied on mixed softwood chips. The cooking ability was studied by varying the alkali and duration of the cook. Pulps with kappa numbers varying from 30 to 70 were obtained. The bleaching ability of these pulps was studied and compared to control kraft pulps. The prehydrolyzed pulps were shown to be more efficiently delignified by oxygen than the control kraft pulps starting from the same kappa number. Furthermore, the final bleaching was also easier for these pulps. It was also shown that extensive oxygen delignification applied on high-kappa pre-hydrolyzed pulps could be a way to improve the overall yield, which is a prerequisite for the development of such biorefinery concepts. Lignin was isolated from the control kraft and the two pre-hydrolyzed kraft pulps and analyzed by 13C NMR. Lignins from pre-hydrolyzed kraft pulps had similar free phenolic groups content to the control kraft lignin, but their aliphatic hydroxyl groups and β-O-4 content were lower than for the control lignin. The quaternary carbon content was the same for all the samples.

Fate of Residual Lignin during Delignification of Kraft Pulp by Trametes versicolor

1998 ◽  
Vol 64 (6) ◽  
pp. 2117-2125 ◽  
Author(s):  
Ian D. Reid
Keyword(s):  
Trametes Versicolor ◽  
Kraft Pulp ◽  
Lignin Degradation ◽  
Water Soluble ◽  
Kraft Pulps ◽  
Residual Lignin ◽  
Spruce Wood ◽  
Single Ring ◽  
Enzyme Bleaching ◽  
By Products

ABSTRACT The fungus Trametes versicolor can delignify and brighten kraft pulps. To better understand the mechanism of this biological bleaching and the by-products formed, I traced the transformation of pulp lignin during treatment with the fungus. Hardwood and softwood kraft pulps containing 14C-labelled residual lignin were prepared by laboratory pulping of lignin-labelled aspen and spruce wood and then incubated with T. versicolor. After initially polymerizing the lignin, the fungus depolymerized it to alkali-extractable forms and then to soluble forms. Most of the labelled carbon accumulated in the water-soluble pool. The extractable and soluble products were oligomeric; single-ring aromatic products were not detected. The mineralization of the lignin carbon to CO2 varied between experiments, up to 22% in the most vigorous cultures. The activities of the known enzymes laccase and manganese peroxidase did not account for all of the lignin degradation that took place in the T. versicolor cultures. This fungus may produce additional enzymes that could be useful in enzyme bleaching systems.

Production of high yield bleached hardwood kraft pulp: Breaking the kraft pulp yield barrier

TAPPI Journal ◽  
2011 ◽  
Vol 10 (9) ◽  
pp. 37-41 ◽  
Author(s):  
PETER W. HART
Keyword(s):  
Kraft Pulp ◽  
Kraft Pulping ◽  
High Yield ◽  
Pulp Yield ◽  
Recovery Cycle ◽  
High Brightness ◽  
Processing Steps

A modified kraft pulping process has been developed that successfully breaks the traditional hardwood kraft pulp yield barrier. The process produces fully bleached, high brightness hardwood kraft pulp with a yield of greater than 53% on wood. Details of the development and processing steps, along with various recovery cycle impacts, are discussed.

Modeling kraft cooking kinetics of fiber mixes from TMP and unbleached kraft pulps for assessment of old corrugated cardboard delignification

Holzforschung ◽  
2018 ◽  
Vol 72 (8) ◽  
pp. 621-629
Author(s):  
Lucas Dollié ◽  
Gérard Mortha ◽  
Nathalie Marlin
Keyword(s):  
Kraft Pulp ◽  
Kraft Pulping ◽  
Thermomechanical Pulp ◽  
Kraft Pulps ◽  
Characteristic Parameters ◽  
High Quality ◽  
Lignocellulosic Substrates ◽  
Kraft Cooking ◽  
Corrugated Cardboard ◽  
Kinetics Of

AbstractKraft cooking kinetics of three different lignocellulosic substrates have been investigated, namely fibers from unbleached kraft pulp (UBKP from Pinus radiata), fibers from softwood unbleached thermomechanical pulp (TMP), and wood chips for TMP production. UBKP and TMP were considered to be representative of a fiber mixture obtained after the pulping and cleaning of old corrugated cardboards (OCC). The characteristic parameters for fitting a mathematical model for kraft pulping were estimated. Based on the results, a “fiber mixture cooking model” was developed to predict the cooking kinetics of TMP/UBKP mixes, accounting for the proportion of each component. The aim was to tailor OCC upcycling in terms of high quality products, which can be used for various purposes including paper and non-paper applications.

An improved procedure for isolation of residual lignins from hardwood kraft pulps

Holzforschung ◽  
2004 ◽  
Vol 58 (5) ◽  
pp. 464-472 ◽  
Author(s):  
Ewellyn Augsten Capanema ◽  
Mikhail Yurievich Balakshin ◽  
Chen-Loung Chen
Keyword(s):  
Molecular Mass ◽  
Nitrogen Content ◽  
Mass Distribution ◽  
Kraft Pulp ◽  
Molecular Mass Distribution ◽  
Eucalyptus Grandis ◽  
Kraft Pulps ◽  
Carbohydrate Composition ◽  
Residual Lignin ◽  
Hydrolysis Of

Abstract Residual lignin preparations were isolated from birch, aspen and Eucalyptus grandis kraft pulp by enzymatic hydrolysis of the pulps with cellulase:hemicellulase mixture. Residual lignin preparations were characterized by investigation of nitrogen content, carbohydrate composition and molecular mass distribution. The use of enzyme with high activity and optimization of enzyme charge resulted in significant decrease in protein contaminants in residual lignin preparations as compared to previously published results. A second order law correlation between enzyme mass charge and nitrogen content in birch residual lignin preparations indicates a strong effect of enzyme charge on the amount of protein contaminants. However, the enzyme charge in the range studied does not appreciably affect either the yields of the residual lignin preparations or percentage and composition of carbohydrates in these preparations. The optimal enzyme charge was highest for Eucalyptus grandis pulp and lowest for birch pulp. It has been suggested that a significant part of the hardwood residual lignin in pulps, especially in E. grandis pulp, consists of low molecular mass lignin fragments bonded to pulp carbohydrates. Higher amount of glucose in E. grandis residual lignin preparation compared to those from birch and aspen implied a higher frequency of lignin-cellulose bonds in eucalypt pulp. Different fractions of birch residual lignin have rather similar molecular mass distribution, which was not affected by the charge of the enzyme. Eucalypt residual lignin preparation had higher molecular mass than birch residual lignin.

scholarly journals Bleached kraft pulp production from Pinus tecunumanii (Eguiluz e Perry)

2005 ◽  
Vol 29 (3) ◽  
pp. 489-494 ◽  
Author(s):  
Leonel F. Torres ◽  
Roberto Melo ◽  
Jorge Luiz Colodette
Keyword(s):  
Kraft Pulp ◽  
Strength Properties ◽  
Kappa Number ◽  
Raw Material ◽  
Kraft Pulps ◽  
Optimum Conditions ◽  
Oxygen Delignification ◽  
Bleached Kraft Pulp ◽  
Pinus Tecunumanii ◽  
Pulp Production

The use of 12-year-old Pinus tecunumanii (Eguiluz e Perry) grown in Colombia was evaluated for bleached kraft pulp production. Kraft pulps of kappa number 30 ± 1 were produced, and oxygen delignified and bleached to 90% ISO with ECF processes. The bleached pulps produced under optimum conditions were evaluated with regard to their strength properties. Pinus tecunumanii wood required low effective alkali charge to reach the desired kappa number and the unbleached pulp showed high oxygen delignification efficiency and bleachability when a OD(EO)DED sequence was used. The bleached pulps presented good physical-mechanical properties, which are comparable to those obtained with more traditional pines such as Pinus taeda and Pinus radiata. The results demonstrate that this tropical pine species is a suitable raw material for bleached kraft pulp production

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