The final bleaching of eucalypt kraft pulps with hydrogen peroxide: relationship with industrial ECF bleaching history and cellulose degradation

2010 ◽  
Vol 86 (3) ◽  
pp. 381-390 ◽  
Author(s):  
Pedro E. G. Loureiro ◽  
Dmitry V. Evtuguin ◽  
M. Graça V. S. Carvalho
Keyword(s):  
Hydrogen Peroxide ◽  
Cellulose Degradation ◽  
Kraft Pulps ◽  
Ecf Bleaching

Initiating ECF bleaching sequences of eucalyptus kraft pulps with Z/D and Z/E stages

Holzforschung ◽  
2010 ◽  
Vol 64 (1) ◽  
Author(s):  
Juan C. García ◽  
Francisco López ◽  
Antonio Pérez ◽  
M. Angels Pèlach ◽  
Pere Mutjé ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Chlorine Dioxide ◽  
Ecological Impact ◽  
Substantial Reduction ◽  
Reference Sequence ◽  
Kraft Pulps ◽  
Eucalyptus Kraft Pulp ◽  
The Impact ◽  
Ecf Bleaching ◽  
Ozone Bleaching

Abstract Ozone bleaching is a common practice in pulping, and also of eucalyptus, where it is usually applied in combination with bleaching sequences based on oxygen, hydrogen peroxide, or chlorine dioxide. Ozone has been proven to be a highly efficient and competitive bleaching chemical in terms of delignification efficiency, low costs, and reducing ecological impact. The objective of the present work was to evaluate technology with ozone/alkaline extraction (Z/E) and ozone/chlorine dioxide (Z/D) for bleaching of eucalyptus kraft pulp. Primarily, the impact of these bleaching steps on refinability and quality of pulp should be investigated. As reference, the sequence D*(EP)D (hot chlorine dioxide, extraction in presence of hydrogen peroxide, chlorine dioxide) was selected, which is considered as the state-of-the-art bleaching in elemental chlorine free (ECF) bleaching technology. Various bleaching sequences with ozone in their first step (Z/D(EP)DP, Z/D(EP)DD, Z/EDP, Z/EDD and A*Z/EDP) were found to provide kraft pulps of similar brightness and in similar yield as the reference sequence D*(EP)D. The kappa number, viscosity, and the contents of glucose and xylose, and hexenuronic acid of the pulps were also similar. In addition, the Z sequences resulted in a substantial reduction of the total chlorine dioxide consumption (more than 30.3% in all cases). The A*Z/EDP sequence, which proved to be the most efficient, yielded 87.5% ClO2 reduction. The studied bleaching sequences also resulted in substantially improved brightness reversal with regard to the reference sequence. The sequence A*Z/EDP was also the most efficient as regards the removal or organochlorines (OX) from the pulp and their reduction in the effluents (AOX). Ozone bleaching sequences improved paper strength, especially with the A*Z/EDP sequence.

scholarly journals Use of TOF-SIMS for the analysis of surface metals in H2O2-bleached lignocellulosic fibers

2001 ◽  
Vol 73 (12) ◽  
pp. 2047-2058 ◽  
Author(s):  
Douglas G. Mancosky ◽  
Lucian A. Lucia
Keyword(s):  
Hydrogen Peroxide ◽  
Inductively Coupled Plasma ◽  
Secondary Ion Mass Spectrometry ◽  
Black Spruce ◽  
Fiber Strength ◽  
Cellulose Degradation ◽  
Fiber Surface ◽  
Peroxide Bleaching ◽  
Alkaline Peroxide ◽  
Tof Sims

Oxidation of cellulose, caused by metal-catalyzed hydrogen peroxide decomposition, is one of the main potential reactions that can occur during the alkaline peroxide bleaching of pulp. This oxidation decreases the individual fiber strength and thus the sheet strength. The bleaching reaction should be controlled to limit cellulose degradation. The goal of this project was to characterize the fiber surface metal distribution using time-of-flight secondary ion mass spectrometry (TOF-SIMS) on laboratory-generated hydrogen peroxide-bleached pulps. For this study, a single black spruce was chosen and kraft pulped. Peroxide bleaching was conducted via benchtop polyethylene bag bleaching in a temperature-controlled waterbath. The overall metals content was determined using inductively coupled plasma (ICP), whereas the surface metals were determined with TOF-SIMS. Many fundamental approaches to study metal identity and content in fibers have been undertaken, including ICP, electron spectroscopy for chemical analysis (ESCA), X-ray fluorescence, and UV­vis. None of these methods can provide the localized density distribution and metal-mapping ability that is available through TOF-SIMS. It has spectacular imaging capabilities that were exploited for evaluating metals on the fiber sheets used in this work. The samples were subjected to other sheet and fiber testing. Tests conducted on select samples included brightness and viscosity. Factors in this experiment included metal addition, chelation, and peroxide charge.

Effect of oxygen, ozone and hydrogen peroxide bleaching stages on the contents and composition of extractives of Eucalyptus globulus kraft pulps

2006 ◽  
Vol 97 (3) ◽  
pp. 420-428 ◽  
Author(s):  
Carmen S.R. Freire ◽  
Armando J.D. Silvestre ◽  
Carlos Pascoal Neto ◽  
Dmitry V. Evtuguin
Keyword(s):  
Hydrogen Peroxide ◽  
Eucalyptus Globulus ◽  
Kraft Pulps ◽  
Peroxide Bleaching ◽  
Effect Of Oxygen

Upgrading of paper-grade pulps to dissolving pulps by nitren extraction: Optimisation of extraction parameters and application to different pulps

Holzforschung ◽  
2006 ◽  
Vol 60 (4) ◽  
pp. 347-354 ◽  
Author(s):  
Ron Janzon ◽  
Jürgen Puls ◽  
Bodo Saake
Keyword(s):  
Kraft Pulp ◽  
Cellulose Degradation ◽  
The Other ◽  
Decisive Factor ◽  
Kraft Pulps ◽  
Chemical Pulps ◽  
Dissolving Pulps ◽  
Sulfite Pulp ◽  
Extraction Parameters ◽  
Birch Kraft Pulp

Abstract Xylans were selectively removed from paper-grade pulps by nitren extraction to produce dissolving pulps. Extraction parameters were optimised for a birch kraft pulp regarding time, temperature, liquor/pulp ratio, and total nitren charge. Furthermore, the applicability of the method was investigated for two other kraft pulps obtained from eucalyptus and mixed softwood, and for one beech sulfite pulp. Extracted pulps were characterised regarding their carbohydrate content and Cuen viscosity. The nitren charge was a decisive factor for xylan removal and pulp purity. The combination of a high nitren concentration and low liquor/pulp ratio was most effective for xylan removal. However, a high liquor/pulp ratio with a lower nitren concentration proved to be more selective and minimised cellulose degradation as well. Glucomannans were almost insoluble under the extraction conditions investigated. Therefore, softwood pulps were not suitable for the upgrading of chemical pulps to dissolving pulps by nitren extraction. On the other hand, hardwood pulps obtained by kraft and sulfite processes contained 96–97% cellulose after nitren extraction.

ECF Bleaching of Pre-Hydrolyzed Larix Kraft Pulp for Production of Dissolving Pulp

2013 ◽  
Vol 634-638 ◽  
pp. 386-390
Author(s):  
Zhi Li ◽  
Jun Li ◽  
Jun Xu
Keyword(s):  
Hydrogen Peroxide ◽  
Chlorine Dioxide ◽  
Kraft Pulp ◽  
Kappa Number ◽  
Alkaline Extraction ◽  
Polymerization Degree ◽  
Oxygen Delignification ◽  
Elemental Chlorine ◽  
Pulp Properties ◽  
Ecf Bleaching

Elemental Chlorine Free (ECF) bleaching sequence of O1/O2D0EOPD1D2 was adopted to bleach the pro-hydrolyzed Larix kraft pulp, where O1/O2 was two-stage oxygen delignification without interstage treatment, D was chlorine dioxide bleaching, EOP was pressurized alkaline extraction strengthened by hydrogen peroxide. Keeping bleaching temperature and time unchanged, sodium hydroxide charge(NaOH) in O1 stage, chlorine dioxide(ClO2) charge in D0 stage and D2 stage were studied, pulp properties such as brightness, kappa number, alpha-cellulose, pentosan and polymerization degree were measured and compared to establish optimal bleaching conditions. Results show that the optimal charge of NaOH in O1 stage is 2.5%, ClO2 in D0 and D2 stage are 2.5%, 0.6%, and the pulp gained at the optimal bleaching conditions has the properties of 93.9% of alpha-cellulose, 2.60% of pentosan, 375.5 ml/g of viscosity and 86.6%ISO of brightness.

Extension of a steady-state chlorine dioxide brightening model for Z-ECF bleaching of softwood kraft pulps

TAPPI Journal ◽  
2021 ◽  
Vol 20 (3) ◽  
pp. 186-197
Author(s):  
BRIAN N. BROGDON ◽  
LUCIAN A. LUCIAN
Keyword(s):  
Steady State ◽  
Linear Relationship ◽  
Chlorine Dioxide ◽  
Current Model ◽  
Kappa Number ◽  
Kraft Pulps ◽  
Current Investigation ◽  
Elemental Chlorine ◽  
Steady State Model ◽  
Ecf Bleaching

Earlier studies developed a steady-state model to predict the brightness and/or bleach consumption during the chlorine dioxide brightening (D1) of softwood pulps produced by conventional elemental-chlorine-free (ECF) sequences. This model relates the chlorine dioxide consumed to the brightness gains predicated upon an asymptotic D1 brightness limit, an incoming D1 pulp brightness, and an equation parameter (β11). The current investigation examines the application of this model to ECF sequences that use ozone delignification (Z-ECF). Literature D1 data from various Z-ECF bleaching studies, which investigated OZ, OD0/Z, and OZ/D0 delignification, were fitted to the model. The β11 parameter was found to be linearly correlated to the entering kappa number. Interestingly, this linear relationship was found to be identical to the relationships observed when modeling the D1 stage for conventional ECF and chlorine-based bleach sequences. Subtle differences in D1 brightening response in the model among the various bleach sequences are reflected by incoming pulp brightness (at the same kappa number). The current model is used to illustrate how alterations to Z-ECF delignification affect D1 brightening and chlorine dioxide consumption.

Bleachability of Alkaline Pulps. Part 1. The Importance of β-Aryl Ether Linkages in Lignin

Holzforschung ◽  
2000 ◽  
Vol 54 (6) ◽  
pp. 609-617 ◽  
Author(s):  
G. Gellerstedt ◽  
W. Wafa Al-Dajani
Keyword(s):  
Hydrogen Peroxide ◽  
Structural Studies ◽  
Kraft Pulps ◽  
Residual Lignin ◽  
Aryl Ether ◽  
Different Types

Summary Analytical and structural studies were done on different types of alkaline pulps and their isolated residual lignins. Although having the same degree of delignification after cooking, some pulps were easier to bleach than others. All isolated residual lignins were found to contain β-aryl ether (β-O-4) structures in reasonable amounts when analysed by thioacidolysis (≥10 % of the native lignin value). At decreasing kappa numbers, there was also a corresponding decrease in the amount of β-aryl ether structures in the residual lignin. Moreover, a high β-aryl ether content in the unbleached residual lignin after cooking was found to contribute to a better bleachability of the pulp, especially when hydrogen peroxide stages were involved. At the same degree of delignification, the superior bleachability of alkaline sulfite pulps over kraft pulps was shown to be attributable to a higher content of β-aryl ether linkages in the former type of pulps.

Activated hydrogen peroxide decolorization of a model azo dye-colored pulp

Holzforschung ◽  
2015 ◽  
Vol 69 (6) ◽  
pp. 677-683 ◽  
Author(s):  
Elsa Walger ◽  
Camille Rivollier ◽  
Nathalie Marlin ◽  
Gérard Mortha
Keyword(s):  
Hydrogen Peroxide ◽  
Azo Dye ◽  
Kraft Pulp ◽  
Dye Removal ◽  
Cellulose Degradation ◽  
Degree Of Polymerization ◽  
Radical Mechanism ◽  
Bleached Kraft Pulp ◽  
Free Radical Mechanism ◽  
Alkaline Conditions

Abstract Recovered fibers are reused for manufacturing bright paper after deinking and fiber decolorization. This second process generally starts with an alkaline hydrogen peroxide (H2O2) stage, referred to as P. However, the color-stripping effect of P is often limited due to the low reactivity of H2O2 on the azo groups of dyes. The purpose of this study was to improve the removal of these azo dyes by H2O2. A bleached kraft pulp was dyed with a model azo dye and submitted to activated H2O2 bleaching. Phenanthroline and copper(II)-phenanthroline (Cu-Phen) served as activating compounds. The color-stripping trials were carried out at weak or conventional alkaline pH. The results were mainly evaluated in terms of dye removal index and degree of polymerization of cellulose. The theoretical composition of Cu-Phen in the bleaching conditions was calculated by means of the geochemical software PHREEQC. The results show that Cu-Phen was able to activate H2O2 color stripping, although it was accompanied by additional cellulose degradation. Moreover, the color stripping was more effective under alkaline conditions, in which case CuPhen(OH)2 would be present. Two hypotheses are proposed to explain this activated decolorization: a free radical mechanism and the influence of CuPhen(OH)2 as an activating species.

Effect of a novel enzyme on fibre morphology during ECF bleaching of oxygen delignified Eucalyptus kraft pulps

2000 ◽  
Vol 74 (2) ◽  
pp. 135-140 ◽  
Author(s):  
A.L. Torres ◽  
M.B. Roncero ◽  
J.F. Colom ◽  
F.I.J. Pastor ◽  
A. Blanco ◽  
...  
Keyword(s):  
Kraft Pulps ◽  
Fibre Morphology ◽  
Ecf Bleaching

Degradation of wood veneers by Fenton's reagents: Effects of wood constituents and low molecular weight phenolic compounds on hydrogen peroxide decomposition and wood tensile strength loss

Holzforschung ◽  
2010 ◽  
Vol 64 (3) ◽  
Author(s):  
Yanjun Xie ◽  
Zefang Xiao ◽  
Barry Goodell ◽  
Jody Jellison ◽  
Holger Militz ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Molecular Weight ◽  
Tensile Strength ◽  
Metal Binding ◽  
Cellulose Degradation ◽  
Iron Concentration ◽  
Wood Decay ◽  
Brown Rot ◽  
Strength Loss ◽  
Low Molecular Weight

AbstractPine wood (Pinus sylvestris) veneer strips were incubated in acetate buffer containing hydrogen peroxide and Fe ions (Fenton's reagent) to mimic aspects of brown rot decay and to assess the degradation of cellulose in wood via measurement of tensile properties (measured in a zero-span mode). Varying the type of iron (ferrous or ferric sulfate) mixed with H2O2did not yield significant differences in the rates of H2O2concentration and tensile strength reduction. However, increasing the amount of wood material (the number of wood strips) in the reaction mixture elevated Fe(III) reduction in solution, indicating that wood constituents participated in this reaction. Increasing concentrations of Fe(III) in the reaction mixture resulted in a decrease in H2O2in solution. Despite an increase in iron concentration and H2O2decomposition under these conditions, a uniform and consistent strength loss of 30% was observed at all Fe(III) concentrations tested. At fixed Fe(III) concentrations, increasing the H2O2concentration linearly increased the strength loss of the veneers up to approximately 50% within 24 h. The addition of a low molecular weight, metal-binding, phenolic compound (2,3-dihydroxybenzoic acid) and of a non-chelating hydroquinone to the reaction mixtures entailed a more rapid consumption of H2O2; however, the tensile strength loss of the veneers decreased with increasing concentration of the phenolics. Thus, in contrast to previous studies on cellulose degradation, phenolics reduced the degree of wood decay in a Fenton system.

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