The nature of chromophores in high-extractives mechanical pulps: Western red cedar (Thuja plicata Donn) chemithermomechanical pulp (CTMP)

Keating, Jeffrey; Johansson, C. Ingemar; Saddler, John N.; Beatson, Rodger P.

doi:10.1515/hf.2006.057

Cited by 19 publications

(14 citation statements)

References 11 publications

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“…[16,17] Absorption coefficients were determined at three wavelengths (357, 457, and 550 nm) corresponding to previously determined absorption maxima in the diffuse reflectance UV. [11] …”

Section: Resultsmentioning

confidence: 99%

“…In previous work, [11] we treated western red cedar mechanical pulp with borohydride, peroxide, and by acetylation and monitored the changes in both the UV-visible and diffuse reflectance infra-red spectra. This allowed us to identify three main components, with different absorption maxima in the UVvisible spectra, which contributed to the color in western red cedar.…”

Section: Discussionmentioning

confidence: 99%

“…In an effort to develop procedures capable of efficiently brightening cedar mechanical pulp to high brightness levels we are conducting a fundamental investigation into the nature of the color in western red cedar mechanical pulps. [9][10][11] This article reports the results of our investigation into the peroxide brightening kinetics of western red cedar CTMP and the factors that limit its efficacy.…”

Section: Introductionmentioning

confidence: 99%

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Kinetics of Hydrogen Peroxide Brightening of Western Red Cedar (Thuja plicata Donn) CTMP

Keating

Johansson

Saddler

et al. 2008

J. of Wood Chem. & Tech.

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The use of western red cedar mechanical pulp is limited by its very low brightness. This article presents the kinetic expressions for hydrogen peroxide brightening of western red cedar chemimechanical pulp. The significance of the results for the reaction mechanism and for brightening under practical conditions is discussed. The kinetics of peroxide brightening of western red cedar chemimechanical pulp was monitored at the three absorption maxima-357 nm, 457 nm, and 550 nm-in the UV-visible spectra. The reaction order with respect to hydrogen peroxide was around 1 at all three wavelengths. The reaction order with respect to chromophores was approximately 2.4 at the higher wavelengths and 5 at 357 nm. The kinetic equations were successful in predicting brightness values obtained under practical conditions.

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“…[16,17] Absorption coefficients were determined at three wavelengths (357, 457, and 550 nm) corresponding to previously determined absorption maxima in the diffuse reflectance UV. [11] …”

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Kinetics of Hydrogen Peroxide Brightening of Western Red Cedar (Thuja plicata Donn) CTMP

Keating

Johansson

Saddler

et al. 2008

J. of Wood Chem. & Tech.

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“…Strong experimental support was presented for the direct photo-oxidation of hydroquinones to p-quinones, whereas hydroquinones could be identified in pulps before photoirradiation by Raman methods (Agarwal 1998). On the contrary, the role of o-quinones in chemithermomechanical pulps (CTMP) of western red cedar was emphasized by Keating et al (2006).…”

Section: Introductionmentioning

confidence: 99%

Photoyellowing of chemically modified chemithermomechanical pulps (CTMP) from Eucalyptus globulus under various atmospheres

et al. 2013

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Chemithermomechanical pulps (CTMP) were prepared from Eucalyptus globulus and photoirradiated, and the responses have been examined by means of ultraviolet (UV) microspectrophotometer. The absorbance in the UV spectra of fiber walls increased in the range of 300 of 350 nm as a result of photoirradiation, indicating the formation of conjugated double-bound systems in the fiber walls. These spectral changes occurred only on the irradiated surface of sheets. CTMP photoirradiation under various atmospheres indicated that the presence of oxygen in the irradiation atmosphere is not necessary for CTMP yellowing. In nitrogen or vacuum, photoyellowing was at the same level as observed under oxygen. This observation was interpreted as a result of direct elimination of proton radicals from free phenolic groups and/or cleavage of β-aryl ether linkages. This induced probably the excited triplet state of α-carbonyl structures in CTMP, which leads to chromophore formation in the absence of oxygen. Reduction of CTMP with sodium borohydride impeded effectively the effects of photoirradiation only in the absence of oxygen. On the contrary, acetylation of CTMP had no effect in the absence of oxygen but led to photobleaching in the presence of oxygen.

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“…They are defined, as a rule, as dimeric phenylpropans and among their intermonomeric linkages, the b-b bonds are typical. As secondary metabolites, they widely occur in the plant kingdom (Ayres and Loike 1990) and also in barks ) and callus resins (Holmbom et al 2008), especially in the knotwood of coniferous trees (Anderegg and Rowe 1974;Willför et al 2003b), which may cause problems as sources of chromophores during chemithermomechanical pulp production (Keating et al 2006). The lignan 7-hydroxymatairesinol can be isolated on an industrial scale from the knotwood of Norway spruce (Picea abies) and then utilized as a substrate for semi-synthetic preparation of a large number of other lignans, among them matairesinol (Holmbom et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Chemical characterization of polymerized products formed in the reactions of matairesinol and pinoresinol with the stable radical 2,2-diphenyl-1-picrylhydrazyl

et al. 2012

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Polymerization reactions of the lignans matairesinol and pinoresinol with the stable radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) were studied. The reactions were rapid and almost quantitative. The molecular weight distribution (MWD) of the formed lignan dimers and polymers was determined by high-performance size-exclusion chromatography (HPSEC) combined with evaporative light-scattering detection (ELSD), and the compounds were characterized by HPLC-MS, pyrolysis-GC/MS, NMR, MALDI-ToF-MS, and GC-MS of the monomeric and dimeric units formed by KMnO 4 oxidation. The yield of high-MW polymers is higher for pinoresinol (69%) than for matairesinol (43%). According to the HPSEC-ELSD analyses, the MWD is also broader for the pinoresinol polymers. The latter seem to consist mainly of hepta-hexacontalignans (MW 2.5-21.4 kDa), whereas the matairesinol polymers are mainly penta-pentadecalignans (MW 1.8-5.3 kDa). The polymers seem to contain mainly unmodified lignan units linked by 5-59 bonds.

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The nature of chromophores in high-extractives mechanical pulps: Western red cedar (Thuja plicata Donn) chemithermomechanical pulp (CTMP)

Abstract: Identification of the three chromophores provides a basis for studies of the kinetics of brightening of western red cedar mechanical pulps.

Cited by 19 publications

References 11 publications

Kinetics of Hydrogen Peroxide Brightening of Western Red Cedar (Thuja plicata Donn) CTMP

Kinetics of Hydrogen Peroxide Brightening of Western Red Cedar (Thuja plicata Donn) CTMP

Photoyellowing of chemically modified chemithermomechanical pulps (CTMP) from Eucalyptus globulus under various atmospheres

Chemical characterization of polymerized products formed in the reactions of matairesinol and pinoresinol with the stable radical 2,2-diphenyl-1-picrylhydrazyl

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