Influence of Kraft Pulping on Carboxylate Content of Softwood Kraft Pulps

2006 ◽  
Vol 45 (13) ◽  
pp. 4509-4516 ◽  
Author(s):  
Zheng Dang ◽  
Thomas Elder ◽  
Arthur J. Ragauskas
Keyword(s):  
Kraft Pulping ◽  
Kraft Pulps ◽  
Carboxylate Content

scholarly journals Chemical characteristics and Kraft pulping of tension wood from Eucalyptus globulus labill

2012 ◽  
Vol 36 (6) ◽  
pp. 1163-1172 ◽  
Author(s):  
María Graciela Aguayo ◽  
Regis Teixeira Mendonça ◽  
Paulina Martínez ◽  
Jaime Rodríguez ◽  
Miguel Pereira
Keyword(s):  
Eucalyptus Globulus ◽  
Lignin Content ◽  
Strength Properties ◽  
Kraft Pulping ◽  
Pulp Yield ◽  
Chemical Characteristics ◽  
Kraft Pulps ◽  
Opposite Wood ◽  
Alkali Consumption ◽  
Pulp Strength

Tension (TW) and opposite wood (OW) of Eucalyptus globulus trees were analyzed for its chemical characteristics and Kraft pulp production. Lignin content was 16% lower and contained 32% more syringyl units in TW than in OW. The increase in syringyl units favoured the formation of β-O-4 bonds that was also higher in TW than in OW (84% vs. 64%, respectively). The effect of these wood features was evaluated in the production of Kraft pulps from both types of wood. At kappa number 16, Kraft pulps obtained from TW demanded less active alkali in delignification and presented slightly higher or similar pulp yield than pulps made with OW. Fiber length, coarseness and intrinsic viscosity were also higher in tension than in opposite pulps. When pulps where refined to 30°SR, TW pulps needed 18% more revolutions in the PFI mill to achieve the same beating degree than OW pulps. Strength properties (tensile, tear and burst indexes) were slightly higher or similar in tension as compared with opposite wood pulps. After an OD0(EO)D1 bleaching sequence, both pulps achieved up to 89% ISO brightness. Bleached pulps from TW presented higher viscosity and low amount of hexenuronic acids than pulps from OW. Results showed that TW presented high xylans and low lignin content that caused a decrease in alkali consumption, increase pulp strength properties and similar bleaching performance as compared with pulps from OW.

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.

Kinetics of ASAM and Kraft Pulping of Eucalypt Wood (Eucalyptus globulus)

Holzforschung ◽  
2002 ◽  
Vol 56 (1) ◽  
pp. 85-90 ◽  
Author(s):  
Isabel Miranda ◽  
Helena Pereira
Keyword(s):  
Eucalyptus Globulus ◽  
Initial Period ◽  
Reaction Times ◽  
Kraft Pulping ◽  
Kraft Pulps ◽  
Final Phase ◽  
Lower Mass ◽  
Lignin Removal ◽  
Mass Losses ◽  
Kinetics Of

Summary The kinetics of ASAM and kraft pulping of eucalypt wood (Eucalyptus globulus) were studied in relation to delignification and polysaccharide removal. In comparison to kraft, ASAM pulping had lower mass losses and delignification for the same temperature and reaction times (59.2% at Kappa 25 vs 50.0% at Kappa 17, at 180°C). The ASAM pulps have a higher brightness. ASAM pulping had a short initial period with no mass loss and lignin removal, followed by two reaction phases: a main phase where 61% of lignin was removed (at 180°C) and a subsequent final phase. In comparison to kraft, the main delignification rates of ASAM pulping were approximately 2.5 slower (at 180°C, −1.8 × 10−2 min−1 for ASAM and −4.2 × 10−2 for kraft pulping), and the calculated Arrhenius activation energies were higher (132.4 kJ mol−1 and 83.5 kJ mol−1, respectively). The loss of cellulose was relatively small (12.5 %) and lower than in kraft pulps.

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.

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.

Chemithermomechanical and kraft pulping of Pinus radiata wood chips after the hydrothermal extraction of hemicelluloses

Holzforschung ◽  
2015 ◽  
Vol 69 (1) ◽  
pp. 33-40 ◽  
Author(s):  
Pablo Reyes ◽  
André Ferraz ◽  
Miguel Pereira ◽  
Jaime Rodríguez ◽  
Regis Teixeira Mendonça
Keyword(s):  
Pinus Radiata ◽  
Energy Savings ◽  
Kraft Pulping ◽  
Wood Chips ◽  
Pulp Yield ◽  
Kraft Pulps ◽  
Pressurized Water ◽  
Pulp Viscosity ◽  
Hemicellulose Removal ◽  
Hydrothermal Extraction

Abstract Pinus radiata D. Don wood chips were submitted to a hydrothermal (HT) process, which is a pretreatment with pressurized water at P-factors of 20 (E1) and 1200 (E2), leading to 27% and 56% of hemicellulose removal, respectively. The residual wood chips were pulped by the chemithermomechanical (CTMP) and kraft processes. The pulp yield in the HT/CTMP process was in the range of 56–75%. The cellulose yields were not affected by the HT pretreatment, whereas the solubilization of hemicelluloses and lignin was intensified. The HT process provided energy savings in the refining of CTMP pulps, and the E1/CTMP pulp had a similar tensile and increased tear strength as the control wood. For kraft pulping, the HT wood chips demanded more active alkali (AA) to achieve a κ number (KN) of 30, and consequently, a decrease in pulp yield was observed (47.2% yield in the control and 44.4% and 37.8% in the E1 and E2 pulps, respectively). The fiber length decreased in the E1 and E2 kraft pulps compared with their control samples. In the E1 pulps, the tensile, tear, and burst indexes decreased by 10%, 25%, and 30%, respectively. Considering the low hemicellulose content and pulp viscosity in the range of 800–900 ml g-1, the mild HT process of P. radiata would be better suited for preparing cellulose-rich materials instead of paper-grade pulps under the biorefinery concept.

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.

Evaluation of beetle-killed white spruce for pulp and paper

1983 ◽  
Vol 13 (2) ◽  
pp. 246-250 ◽  
Author(s):  
Richard A. Werner ◽  
Erwin E. Elert ◽  
Edward H. Holsten
Keyword(s):  
White Spruce ◽  
Strength Properties ◽  
Kraft Pulping ◽  
Pulp Yield ◽  
Kraft Pulps ◽  
High Quality ◽  
South Central ◽  
Dead Trees ◽  
Standing Trees ◽  
First Results

A kraft pulping study on standing white spruce (Piceaglauca (Moench) Voss) killed by spruce beetles (Dendroetonusrufipennis (Kirby)) in south central Alaska showed no difference in pulp yield between trees dead for 1 year and those dead for as long as 50 years. Strength properties of beetle-killed white spruce remained extremely high in all dead trees regardless of how long they had been dead, so they apparently could be used for producing high-quality kraft pulps. These are the first results reported in which standing trees dead for as long as 50 years produced high-quality bleached and unbleached pulps.

A Comparative CP/MAS 13C-NMR Study of the Supermolecular Structure of Polysaccharides in Sulphite and Kraft Pulps

Holzforschung ◽  
2002 ◽  
Vol 56 (2) ◽  
pp. 179-184 ◽  
Author(s):  
Eva-Lena Hult ◽  
Per Tomas Larsson ◽  
Tommy Iversen
Keyword(s):  
Supermolecular Structure ◽  
Kraft Pulping ◽  
Magic Angle ◽  
Kraft Pulps ◽  
General Observation ◽  
Spectral Fitting ◽  
Nmr Study ◽  
Cellulose Iβ ◽  
Cp Mas 13C Nmr ◽  
C Nmr

Summary The supermolecular structure of polysaccharides in unbleached sulphite pulps and kraft pulps was investigated by CP/MAS 13C-NMR (Cross Polarisation Magic Angle Carbon-13 Nuclear Magnetic Resonance) in combination with spectral fitting. The cellulose crystallinity was found to be higher in the kraft pulps than in the sulphite pulps. Acellulose Iα to cellulose Iβ conversion was observed during kraft pulping but not during sulphite pulping. The sulphite pulps exhibited smaller lateral fibril aggregate dimensions than the kraft pulps. The spectral behaviour of the hemicelluloses in the sulphite pulps was different from that in the kraft pulps. The general observation is that the supermolecular structure of the polysaccharides in the investigated sulphite pulps is very similar to the structure observed in wood.

Near-neutral pre-extraction of hemicelluloses and subsequent kraft pulping of southern mixed hardwoods

TAPPI Journal ◽  
2011 ◽  
Vol 10 (1) ◽  
pp. 7-15 ◽  
Author(s):  
SUNG-HOON YOON ◽  
MEHMET SEFIK TUNC ◽  
ADRIAAN VAN HEININGEN
Keyword(s):  
Dry Weight ◽  
Kraft Pulping ◽  
Weight Basis ◽  
Alkaline Solutions ◽  
Pulp Yield ◽  
Kraft Pulps ◽  
Alkaline Ph ◽  
Green Liquor ◽  
Kraft Cooking ◽  
High Alkali

Southern mixed hardwood chips were extracted with alkaline solutions at different chemical charges, times (45-110 min), and temperatures (125°C-160°C). At high alkali charges (10% and 20% sodium hydroxide [NaOH] as sodium oxide [Na2O]), the extract was strongly alkaline (pH about 13) and 17%-40% of the wood was dissolved. Subsequent kraft cooking of the extracted chips yielded 5%-7% less pulp than that of control kraft pulps. However, at reduced alkali charge, just sufficient to approximately neutralize the acids released during pre-extraction, the pulp yield (on original wood) after subsequent kraft pulping was not affected. In this case, about 5%-10% of the wood substance is removed during pre-extraction with 3% NaOH or 3% green liquor (+0.05% anthraquinone) at 140°C and 160°C for 60, 90, and 110 min. The green liquor extract obtained after 110 min at 160°C contained 2.1% (oven-dry weight basis) of sugars, 2.1% acetic acid, and 1.6% lignin accounting for 64% of the wood weight loss. Kraft pulping of the pre-extracted wood chips performed at 12% effective alkali charge showed significantly improved delignification rates and approximately the same or slightly higher yield than the kraft control at 15% effective alkali. The near-neutral green liquor+anthraquinone pre-extraction kraft pulps showed lower refining response but higher tear resistance and similar tensile strength compared to control kraft pulps.

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