Oxygen-ozone-hydrogen peroxide bleaching sequence of kraft pulp.

New evidences for the role of borohydride pretreatment in hydrogen peroxide bleaching process of eucalyptus chemical pulps were provided, i.e., suppressing the catalysis effect of Fe(iii), decreasing carbonyl groups, and constituent lignin structure.

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Oxidized Derivatives of Lipophilic Extractives Formed during Hardwood Kraft Pulp Bleaching

Holzforschung ◽

10.1515/hf.2003.075 ◽

2003 ◽

Vol 57 (5) ◽

pp. 503-512 ◽

Cited By ~ 11

Author(s):

C. S. R. Freire ◽

A. J. D. Silvestre ◽

C. Pascoal Neto

Keyword(s):

Hydrogen Peroxide ◽

Chlorine Dioxide ◽

Kraft Pulp ◽

Structural Changes ◽

Oxidation Products ◽

Pulp Bleaching ◽

Peroxide Bleaching ◽

Kraft Pulp Bleaching ◽

First Time ◽

Derivatives Of

Summary The structural changes of E. globulus wood extractives during bleaching with chlorine dioxide (D), oxygen (O), ozone (Z) and hydrogen peroxide (P) were studied. The detailed characterisation of the extractive derivatives detected in the partially bleached D, O, P and Z pulps was achieved by performing reactions of pure reference compounds with the different bleaching agents. The results show that the unsaturated sterols and fatty acids are extensively degraded during chlorine dioxide and ozone bleaching and only partially degraded during oxygen and hydrogen peroxide bleaching. The corresponding saturated extractives as well as the long chain aliphatic alcohols and ω-hydroxyfatty acids were stable during bleaching. The main oxidation products of β-sitosterol and oleic and linoleic acids, including one chlorinated derivative of linoleic acid, were identified here for the first time in E. globulus bleached pulps and bleaching filtrates.

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Hydrogen peroxide bleaching of hardwood kraft pulp with adsorbed birch xylan and its effect on paper properties

BioResources ◽

10.15376/biores.6.1.721-736 ◽

2011 ◽

Vol 6 (1) ◽

pp. 721-736

Author(s):

Lizi Li ◽

Sanghoon Lee ◽

Hak Lae Lee ◽

Hye Jung Youn

Keyword(s):

Hydrogen Peroxide ◽

Optical Properties ◽

Kraft Pulp ◽

Strength Properties ◽

Pulp Fibers ◽

Paper Properties ◽

Peroxide Bleaching ◽

Initial Ph ◽

The Relationship ◽

Temperature Time

The adsorption of xylan on pulp fibers improves the strength properties of paper. However, the optical properties are decreased significantly. The objective of our research was to bleach hardwood kraft pulp with adsorbed birch xylan by hydrogen peroxide and study the effect of bleaching parameters on paper properties. The bleaching parameters studied included bleaching temperature, time, initial pH as well as MgSO4 dosage. The optical properties (whiteness, brightness, opacity) and physical properties (tensile index, tearing index, bulk) of handsheets made from the pulp bleached with different process variables were measured. The results showed that better optical properties were obtained with higher bleaching temperature, longer bleaching time, and more MgSO4 dosage. Bleaching from an initial pH of 11 provided the highest brightness value. On the other hand, strength properties were improved with decreasing of the bleaching temperature, and increasing the initial pH and MgSO4 dosage. The relationship between strength properties and bleaching time varied depending on bleaching temperature. According to the results, both good mechanical properties and optical properties could be achieved when the operating parameters were controlled properly. Therefore hydrogen peroxide bleaching was proved to be a suitable method for bleaching hardwood kraft pulp with adsorption of birch xylan.

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Application of a Catalyst in Peroxide Bleaching of Eucalyptus Kraft Pulp

Holzforschung ◽

10.1515/hf.2000.068 ◽

2000 ◽

Vol 54 (4) ◽

pp. 407-412 ◽

Cited By ~ 8

Author(s):

L. Kühne ◽

J. Odermatt ◽

T. Wachter

Keyword(s):

Hydrogen Peroxide ◽

Kraft Pulp ◽

Pulp Bleaching ◽

Selective Catalyst ◽

Peroxide Bleaching ◽

Softwood Pulp ◽

Kraft Pulp Bleaching ◽

Eucalyptus Kraft Pulp ◽

Softwood Kraft Pulp

Summary A binuclear [Mn(III)Mn(IV)(μ-O)2(μ-CH3COO)L](ClO4−)2 complex with L = 1,2 Bis-(4,7-dimethyl-1,4,7-triazacyclonon-1-yl)-ethane, described as a selective catalyst in hydrogen peroxide bleaching of softwood pulps, was tested in hardwood kraft pulp bleaching. The catalyst application gave rise to a higher consumption of peroxide which resulted in higher pulp brightness. The delignification improvement caused by the catalyst was shown to be much lower compared to catalysed peroxide bleaching of softwood kraft pulp. In contrast to the results of softwood pulp bleaching no selectivity improvements could be found when using the catalyst in bleaching of eucalyptus kraft pulp.

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Kraft pulp bleaching with a P-stage catalyzed by both bicarbonate and TAED

TAPPI Journal ◽

10.32964/tj18.7.409 ◽

2019 ◽

Vol 18 (7) ◽

pp. 409-414

Author(s):

N. DAS ◽

S.K. BOSE ◽

R.C. FRANCIS

Keyword(s):

Hydrogen Peroxide ◽

Sodium Bicarbonate ◽

Sodium Hydroxide ◽

Sodium Carbonate ◽

Kraft Pulp ◽

Kraft Pulps ◽

Pulp Bleaching ◽

Peroxide Bleaching ◽

Kraft Pulp Bleaching ◽

Peroxide Activation

Peroxide bleaching of softwood and hardwood (eucalypt) kraft pulps was performed in solutions of sodium bicarbonate (NaHCO3), sodium carbonate (Na2CO3), and sodium hydroxide (NaOH). The conventional P stage (hydrogen peroxide + sodium hydroxide; H2O2 + NaOH) was the most effective brightening system without an additional activator. However, peroxide activation by bicarbonate anion (HCO3–) was obvious in all cases where NaHCO3 or Na2CO3 was used. When N,N,N’,N’-tetraacetylethylenediamine (TAED) was added to the bleaching system, Na2CO3 as the alkali source afforded equal or slightly higher bleached brightness compared to NaOH usage for both the softwood and hardwood pulps. This outcome is attributed to simultaneous peroxide activation by HCO3 and TAED. When applied to the eucalypt pulp, the H2O2/Na2CO3/TAED bleaching system also decreased the brightness loss due to thermal reversion.

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The role of copper ions in hydrogen peroxide bleaching: Their origin, removal, and effect on pulp quality

TAPPI Journal ◽

10.32964/tj11.7.37 ◽

2012 ◽

Vol 11 (7) ◽

pp. 37-46 ◽

Cited By ~ 1

Author(s):

PEDRO E.G. LOUREIRO ◽

SANDRINE DUARTE ◽

DMITRY V. EVTUGUIN ◽

M. GRAÇA V.S. CARVALHO

Keyword(s):

Hydrogen Peroxide ◽

Copper Ions ◽

Peroxide Bleaching ◽

Metals Removal ◽

Peroxide Decomposition ◽

Equipment Corrosion ◽

And Performance ◽

And Control ◽

Main Effects

This study puts particular emphasis on the role of copper ions in the performance of hydrogen peroxide bleaching (P-stage). Owing to their variable levels across the bleaching line due to washing filtrates, bleaching reagents, and equipment corrosion, these ions can play a major role in hydrogen peroxide decomposition and be detrimental to polysaccharide integrity. In this study, a Cu-contaminated D0(EOP)D1 prebleached pulp was subjected to an acidic washing (A-stage) or chelation (Q-stage) before the alkaline P-stage. The objective was to understand the isolated and combined role of copper ions in peroxide bleaching performance. By applying an experimental design, it was possible to identify the main effects of the pretreatment variables on the extent of metals removal and performance of the P-stage. The acid treatment was unsuccessful in terms of complete copper removal, magnesium preservation, and control of hydrogen peroxide consumption in the following P-stage. Increasing reaction temperature and time of the acidic A-stage improved the brightness stability of the D0(EOP)D1AP bleached pulp. The optimum conditions for chelation pretreatment to maximize the brightness gains obtained in the subsequent P-stage with the lowest peroxide consumption were 0.4% diethylenetriaminepentaacetic acid (DTPA), 80ºC, and 4.5 pH.

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The Effect of Microwave Treatment on the Hydrogen Peroxide Bleaching of Soda-AQ Wheat Straw Pulp

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.236-238.1307 ◽

2011 ◽

Vol 236-238 ◽

pp. 1307-1312

Author(s):

Chao Jun Wu ◽

Chuan Shan Zhao ◽

Jun Li ◽

Ke FU Chen

Keyword(s):

Hydrogen Peroxide ◽

Wheat Straw ◽

Fiber Length ◽

Weighted Average ◽

Microwave Treatment ◽

Arithmetic Average ◽

Peroxide Bleaching ◽

Bleached Pulp ◽

Infra Red ◽

Wheat Straw Pulp

In this paper, the effect of microwave treatment on the hydrogen peroxide bleaching of Soda-AQ wheat-straw pulp was investigated. The results showed that microwave treatment could increase the brightness of the hydrogen peroxide bleached pulp. The fiber coarseness of microwave enhancing peroxide bleached pulp was higher than that of the peroxide bleached pulp. However, the arithmetic average fiber length, the length weighted average fiber length and weight weighted average fiber length of the former was lower than that of the latter. Fourier transform infra-red spectroscopy (FTIR) and X-ray diffraction (XRD) spectra showed that CrI(%) crystallinity of microwave enhancing peroxide bleached pulp was similar as that of the peroxide bleached pulp but all higher than that of the Soda-AQ wheat-straw pulp. N·O′KI infra-red crystalline index of microwave enhancing peroxide bleached pulp were lower than that of the peroxide bleached pulp. The FTIR spectra of lignin showed that the microwave treatment had some influences on the methoxyl and phenolic group in lignin.

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Influence of Hydrogen Peroxide Bleaching Gels on Color, Opacity, and Fluorescence of Composite Resins

Operative Dentistry ◽

10.2341/11-189-l ◽

2012 ◽

Vol 37 (5) ◽

pp. 526-531 ◽

Cited By ~ 10

Author(s):

CRG Torres ◽

CF Ribeiro ◽

E Bresciani ◽

AB Borges

Keyword(s):

Hydrogen Peroxide ◽

Composite Resin ◽

Color Change ◽

Composite Resins ◽

Control Group ◽

Peroxide Bleaching ◽

Color Changes ◽

Tukey Test ◽

Bleaching Gels ◽

Bleaching Treatment

SUMMARY The aim of the present study was to evaluate the effect of 20% and 35% hydrogen peroxide bleaching gels on the color, opacity, and fluorescence of composite resins. Seven composite resin brands were tested and 30 specimens, 3-mm in diameter and 2-mm thick, of each material were fabricated, for a total of 210 specimens. The specimens of each tested material were divided into three subgroups (n=10) according to the bleaching therapy tested: 20% hydrogen peroxide gel, 35% hydroxide peroxide gel, and the control group. The baseline color, opacity, and fluorescence were assessed by spectrophotometry. Four 30-minute bleaching gel applications, two hours in total, were performed. The control group did not receive bleaching treatment and was stored in deionized water. Final assessments were performed, and data were analyzed by two-way analysis of variance and Tukey tests (p<0.05). Color changes were significant for different tested bleaching therapies (p<0.0001), with the greatest color change observed for 35% hydrogen peroxide gel. No difference in opacity was detected for all analyzed parameters. Fluorescence changes were influenced by composite resin brand (p<0.0001) and bleaching therapy (p=0.0016) used. No significant differences in fluorescence between different bleaching gel concentrations were detected by Tukey test. The greatest fluorescence alteration was detected on the brand Z350. It was concluded that 35% hydrogen peroxide bleaching gel generated the greatest color change among all evaluated materials. No statistical opacity changes were detected for all tested variables, and significant fluorescence changes were dependent on the material and bleaching therapy, regardless of the gel concentration.

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