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.

Deep eutectic solvent delignification: Impact of initial lignin

BioResources ◽  
2017 ◽  
Vol 12 (4) ◽  
pp. 7301-7310
Author(s):  
Veronika Majová ◽  
Silvia Horanová ◽  
Andrea Škulcová ◽  
Jozef Šima ◽  
Michal Jablonský
Keyword(s):  
Lactic Acid ◽  
Oxalic Acid ◽  
Lignin Content ◽  
Choline Chloride ◽  
Deep Eutectic Solvent ◽  
Deep Eutectic Solvents ◽  
Kappa Number ◽  
Kraft Pulps ◽  
Oxygen Delignification ◽  
Detailed Understanding

This study aimed to resolve the issue of the lack of detailed understanding of the effect of initial lignin content in hardwood kraft pulps on pulp delignification by deep eutectic solvents. The authors used Kappa number of the concerned pulp, intrinsic viscosity, and selectivity and efficiency of delignification as the parameters of the effect. The pulp (50 g oven dry pulp) was treated with four different DESs systems based on choline chloride with lactic acid (1:9), oxalic acid (1:1), malic acid (1:1), and system alanine:lactic acid (1:9); the results were compared to those reached by oxygen delignification. The results showed that the pulp with a higher initial lignin content had a greater fraction of easily removed lignin fragments.

Pre-bleaching of kraft acacia pulp

2019 ◽  
Vol 34 (2) ◽  
pp. 165-172 ◽  
Author(s):  
Moinul Haque ◽  
Moumita Nanjiba ◽  
M. Sarwar Jahan ◽  
M. A. Quaiyyum ◽  
M. Zahangir Alam ◽  
...  
Keyword(s):  
Acacia Mangium ◽  
Kappa Number ◽  
Acacia Auriculiformis ◽  
Kraft Pulps ◽  
Oxygen Delignification ◽  
Acid Pretreatment ◽  
Acacia Hybrid ◽  
Pre Treatment ◽  
Hexenuronic Acid ◽  
Peroxyformic Acid

Abstract Kraft pulps from acacia hybrid, Acacia mangium of 8 years old and Acacia auriculiformis of 6, 8 and 10 years old were pre-treated with oxygen, peroxyformic acid and acid treatment prior to bleaching. The kappa number reduction was 52–63 % by oxygen delignification, 31–35 % by peroxyformic acid (PFA) pre-treatment and 11–13 % by acid pre-treatment. Oxygen delignified pulp required less chlorine dioxide charge to reach target brightness. At the consumption of 30 kg ClO2/ton of pulp, the pulp brightness reached to 65–71 % for the untreated pulp, 81–85 % for the oxygen delignified pulp, 81–82 % for the PFA treatment and 79–80 % for acid pre-treated pulp. COD load in bleached effluent was much lower in oxygen delignified pulp. Cold alkali extraction of unbleached and oxygen delignified pulps was also carried out with varying alkali charge to remove hexenuronic acid (HexA) from the pulp. Xylan removal from the pulp was insignificant and resulted in no removal of HexA. Acid pretreatment removed 55.7 % to 17.8 % HexA from acacia hybrid, 57.5 % to 16.3 % from A. auriculiformis of 10 years and 58.6 % to 20.1 % from A. auriculiformis of 6 years old, resulting in improved final pulp brightness.

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.

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.

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

Oxygen delignification of conventional and high alkali cooked softwood Kraft pulps, and study of the residual lignin structure

RSC Advances ◽  
2014 ◽  
Vol 4 (34) ◽  
pp. 17469-17477 ◽  
Author(s):  
Vahid Jafari ◽  
Sara R. Labafzadeh ◽  
Alistair King ◽  
Ilkka Kilpeläinen ◽  
Herbert Sixta ◽  
...  
Keyword(s):  
Kinetic Data ◽  
Kappa Number ◽  
Kraft Pulps ◽  
Residual Lignin ◽  
Oxygen Delignification ◽  
High Alkali ◽  
Lignin Structure

Elucidation of the structure of the residual lignin of high kappa number softwood pulps combined with kinetic data from O-delignification.

Pulp delignification with oxygen and copper(II)-polyimine complexes

Holzforschung ◽  
2014 ◽  
Vol 68 (4) ◽  
pp. 377-384 ◽  
Author(s):  
Basile Gueneau ◽  
Nathalie Marlin ◽  
Alain Deronzier ◽  
Dominique Lachenal
Keyword(s):  
Redox Potential ◽  
Kraft Pulp ◽  
Oxygen Activation ◽  
Kraft Lignin ◽  
Kraft Pulps ◽  
Oxygen Delignification ◽  
Mechanical Pulp ◽  
Bleached Pulp ◽  
Carbohydrate Degradation ◽  
Unbleached Pulp

Abstract Ten Cu(II)-polyimine complexes were tested as potential catalysts in oxygen delignification of softwood kraft pulps. The ligands were chosen from the terpyridine and the phenanthroline families, including several neocuproines. One diamine-phenanthrene (daphen) was also investigated. The main purpose was to examine whether the presence of methyl or phenyl substituents would direct the oxidation toward lignin. As a catalyst for comparison, unsubstituted 1,10-phenanthroline was selected, which is known to activate both delignification and carbohydrate degradation during oxygen bleaching of kraft pulp. The variation of ligands was aiming at the complex solubility and redox potential of the parameters. The experiments were performed on a mixture of mechanical pulp and fully bleached kraft pulps, a fully bleached pulp alone, and an industrial unbleached pulp. Concerning the oxygen activation in delignification of kraft pulp, 4,7-diphenyl-1,10-phenanthroline was as good as 1,10-phenanthroline, but appeared to be more selective, which resulted in a higher DPv of cellulose after treatment. This was interpreted by the structural similarities between the ligand and the kraft lignin and by a better stability of the intermediate complex with lignin. Two Cu(II)-phenanthroline derivatives complexes (4,7- and 5,6-dimethyl-1,10-phenanthroline) were also identified as effective oxygen activators for the removal of native lignin.

Effects of lignin chemistry on oxygen delignification performance

TAPPI Journal ◽  
2018 ◽  
Vol 17 (07) ◽  
pp. 373-381 ◽  
Author(s):  
Valeria Juste Gomes ◽  
Hasan Jameel ◽  
Hou-Min Chang ◽  
Robert Narron ◽  
Jorge Colodette ◽  
...  
Keyword(s):  
Molecular Oxygen ◽  
Chemical Properties ◽  
Kappa Number ◽  
Kraft Pulps ◽  
Residual Lignin ◽  
Reactive Site ◽  
Oxygen Delignification ◽  
Hardwood Species ◽  
Hexenuronic Acid ◽  
The Relationship

The present work focused on characterizing the chemical and structural properties of isolated lignin from six hardwoods and their kraft pulps in an attempt to better understand the relationship between lignin’s chemical properties and resultant oxygen delignification performance. Several hardwood samples were cooked under the same conditions with varying alkali charges to obtain unbleached pulps with kappa numbers between 19 and 20. These pulps were then subjected to an oxygen delignification stage. Both processes were evaluated for pulp quality, residual lignin, and O-stage delignification efficiency. The oxygen delignification stage was carried out under fixed conditions and evaluated with regards to kappa number, which was corrected for hexenuronic acid (HexA) contributions.Results revealed that different hardwood species exhibited differing oxygen delignification efficiencies. A high correlation was found between the O-stage delignification efficiency and the content of phenolic groups in the unbleached lignin, which confirmed that free phenolic groups are the reactive site for molecular oxygen attack. When different hardwood species were compared, the HexA contents were not found to affect O-stage delignification efficiencies.

scholarly journals Evaluation of bleachability on pine and eucalyptus kraft pulps

CERNE ◽  
2013 ◽  
Vol 19 (3) ◽  
pp. 433-439 ◽  
Author(s):  
Marcela Freitas Andrade ◽  
Jorge Luiz Colodette ◽  
Flávia Natalino Oliveira
Keyword(s):  
Production Capacity ◽  
Kappa Number ◽  
Inorganic Materials ◽  
Kraft Pulps ◽  
Oxygen Delignification ◽  
Pulp Bleaching ◽  
Alkaline Leaching ◽  
Pulp Industry ◽  
Reagent Consumption ◽  
Two Stages

In recent decades, the pulp industry has been changing and improving its manufacturing processes in order to enhance production capacity, product quality and environmental performance. The aim of this study was to evaluate the bleachability effect on the efficient washing and alkaline leaching in eucalyptus and pine Kraft pulps using three different bleaching sequences: AD(EP)D, A/D(EP)DP and D HT(EP)DP. This study was carried out in two stages. In the first part, the optimum conditions for pulp bleaching in order to achieve a brightness of 90% ISO were established. The second step was a comparative study between the pulps that received alkaline leaching and efficient washing with reference pulp (without treatment). The brightness, viscosity, kappa number and HexA in pulp were analyzed. The three sequences studied reached the desired brightness, but the sequence AD(EP)D produced a lower reagent consumption for the same brightness. In the three sequences studied, the efficient washing of the pulp after oxygen delignification has contributed significantly to the removal of dissolved organic and inorganic materials in the pulp and the alkaline leaching decreased significantly the pulp kappa number due to a higher pulp delignification and bleachability.

scholarly journals Reactivity of Aliphatic and Phenolic Hydroxyl Groups in Kraft Lignin towards 4,4′ MDI

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2131
Author(s):  
Leonardo Dalseno Antonino ◽  
Júlia Rocha Gouveia ◽  
Rogério Ramos de Sousa Júnior ◽  
Guilherme Elias Saltarelli Garcia ◽  
Luara Carneiro Gobbo ◽  
...  
Keyword(s):  
Experimental Work ◽  
Chemical Structure ◽  
31P Nmr ◽  
Kraft Lignin ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Diphenylmethane Diisocyanate ◽  
Complex Chemical ◽  
Heterogeneous Reactivity ◽  
Phenolic Hydroxyl Groups

Several efforts have been dedicated to the development of lignin-based polyurethanes (PU) in recent years. The low and heterogeneous reactivity of lignin hydroxyl groups towards diisocyanates, arising from their highly complex chemical structure, limits the application of this biopolymer in PU synthesis. Besides the well-known differences in the reactivity of aliphatic and aromatic hydroxyl groups, experimental work in which the reactivity of both types of hydroxyl, especially the aromatic ones present in syringyl (S-unit), guaiacyl (G-unit), and p-hydroxyphenyl (H-unit) building units are considered and compared, is still lacking in the literature. In this work, the hydroxyl reactivity of two kraft lignin grades towards 4,4′-diphenylmethane diisocyanate (MDI) was investigated. 31P NMR allowed the monitoring of the reactivity of each hydroxyl group in the lignin structure. FTIR spectra revealed the evolution of peaks related to hydroxyl consumption and urethane formation. These results might support new PU developments, including the use of unmodified lignin and the synthesis of MDI-functionalized biopolymers or prepolymers.

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