Isolation and identification of residual chromophores in cellulosic materials

Rosenau, Thomas; Potthast, Antje; Milacher, Walter; Hofinger, Andreas; Kosma, Paul

doi:10.1016/j.polymer.2004.07.031

Cited by 60 publications

(16 citation statements)

References 15 publications

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“…Attempts to isolate those structures by treatment of the pulps with hydrolysing enzymes and subsequent extraction failed. Use of the extraction method suggested by Rosenau et al [16,17] did neither lead to completely colourless carbohydrate residues. Analysis of the extract gave evidence to the formation of condensation products of furfural.…”

Section: Resultsmentioning

confidence: 86%

“…However, it is unlikely that they contribute to the yellow-brownish colour that is obtained when TCF-bleached pulps are heated. Even though it was shown that the addition of 5-hydroxymethyl furfural to filter paper leads to a strong discolouration of the paper sample [15] , the structures of the colour forming compounds have not yet been elucidated except in the work done by Rosenau et al [16] . It was shown that so-called ''Theanderproducts'' are formed that can be isolated by a special procedure using the BF 3 -acetic acid complex.…”

Section: Introductionmentioning

confidence: 99%

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Role of Hemicelluloses in the Formation of Chromophores During Heat Treatment of Bleached Chemical Pulps

Beyer

Koch

Fischer

2005

Macromolecular Symposia

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The heat-induced colour formation of TCF-and ECF-bleached chemical pulps has been investigated. Partial hydrolysis of the pulps and analysis of the carboxyl content of the pulps and hydrolysed matter were carried out. It was found that the yellowing tendency of the pulps corresponds to the content of hydrolysable substances. The hydrolysis leads to a considerable removal of the carboxyl groups in the case of hardwood pulps. Differences between softwood and hardwood pulps are discussed in terms of their hemicellulose content. The yellowed pulps were extracted and the extracts were analysed by different NMR and mass spectrometric techniques. Structures of low molecular products were elucidated and the routes of their formation were proposed. The results suggest that the yellowing proceeds in two main steps, i.e. decay of unstable polysaccharide chains such as hemicelluloses to low molecular carbohydrate compounds that subsequently undergo dehydration and condensation reactions to form coloured products.

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Section: Resultsmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Role of Hemicelluloses in the Formation of Chromophores During Heat Treatment of Bleached Chemical Pulps

Beyer

Koch

Fischer

2005

Macromolecular Symposia

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“…Thus, the effect of Z stages on brightness stability can be both beneficial by destroying chromophores and chromogens and detrimental by generating heat-sensitive degradation products (Pouyet et al 2013;Röhrling et al 2002). Some of the chromophores still present in bleached chemical pulps have been identified and quantified (Rosenau et al 2004(Rosenau et al , 2011. They are of the quinone or aromatic furan type.…”

Section: Introductionmentioning

confidence: 99%

Use of UV resonance Raman spectroscopy for assessing the brightness stability of ozone TCF bleached pulp

et al. 2020

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AbstractThis study intends to explain the difference in brightness stability between hardwood ECF and TCFz kraft pulps bleached by DEpDD and A(ZEo)(ZEo)(ZP) sequences respectively, using UV Resonance Raman (UVRR) spectroscopy. The brightness stability of the pulps was tested via dry aging experiments where the Post-Color Number (PCN) of the ECF pulp was twice that of the TCF pulp. The aged and non-aged bleached pulps were analyzed with UVRR spectroscopy to identify the cause of the large difference in PCN. The spectra of ECF and TCF bleached pulps presented clear differences in the intensities of the Raman shifts associated to lignin, lignin-like compounds, and degradation products such as muconic acids. To identify more specifically the compounds affecting the PCN, several post-bleaching treatments were applied on the ECF pulp including single stages (E, B, P, Z) or combinations (ZE, ZB, ZP), and their UVRR spectra analyzed. It was found that alkaline-soluble compounds were the main culprits for the difference in PCN values between ECF and TCFz pulps. ZP combination was the most efficient in eliminating residual lignin and other unsaturated components and for the development of brightness and brightness stability.

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“…Similarly, conservators are interested in preserving their often valuable historic cellulosic documents endangered by the darkening caused by high chromophore content. To meet all of these needs, the chromophores first had to be identified, as done so by application of the CRI (chromophore release and identification) method. , This approach, for the first time, provided access to the chromophoric compounds in cellulose, whereas before only likely structural units, such as conjugated carbonyl structures or quinones, had been surmised. Comparison of the structures allowed distinguishing between “primary” chromophores, originating from carbohydrate matter or respective degradation products, and “secondary” chromophores, which involve process chemicals in their formation, such as for instance sulfur species in rayon production.…”

Section: Introductionmentioning

confidence: 99%

Degradation of the Cellulosic Key Chromophore 5,8-Dihydroxy-[1,4]-naphthoquinone by Hydrogen Peroxide under Alkaline Conditions

et al. 2017

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5,8-Dihydroxy-[1,4]-naphthoquinone (DHNQ) is one of the key chromophores in cellulosic materials. Its almost ubiquitous presence in cellulosic materials makes it a target molecule of the pulp and paper industry's bleaching efforts. In the presented study, DHNQ was treated with hydrogen peroxide under alkaline conditions at pH 10, resembling the conditions of industrial hydrogen peroxide bleaching (P stage). The reaction mechanism, reaction intermediates, and final degradation products were analyzed by UV/vis, NMR, GC-MS, and EPR. The degradation reaction yielded C-C carboxylic acids as the final products. Highly relevant for pulp bleaching are the findings on intermediates of the reaction, as two of them, 2,5-dihydroxy-[1,4]-benzoquinone (DHBQ) and 1,4,5,8-naphthalenetetrone, are potent chromophores themselves. While DHBQ is one of the three key cellulosic chromophores and its degradation by HO is well-established, the second intermediate, 1,4,5,8-naphthalenetetrone, is reported for the first time in the context of cellulose discoloration.

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Isolation and identification of residual chromophores in cellulosic materials

Cited by 60 publications

References 15 publications

Role of Hemicelluloses in the Formation of Chromophores During Heat Treatment of Bleached Chemical Pulps

Role of Hemicelluloses in the Formation of Chromophores During Heat Treatment of Bleached Chemical Pulps

Use of UV resonance Raman spectroscopy for assessing the brightness stability of ozone TCF bleached pulp

Degradation of the Cellulosic Key Chromophore 5,8-Dihydroxy-[1,4]-naphthoquinone by Hydrogen Peroxide under Alkaline Conditions

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