Oxidative Bleaching Research Articles

Metabolism of chlorophyll in higher plants IV. Relationship between fatty acid oxidation and chlorophyll bleaching in plant extracts

Metabolism of chlorophyll in higher plants IV. Relationship between fatty acid oxidation and chlorophyll bleaching in plant extracts

Effect of Bleaching Degree to Soiling and Desoiling Properties of Cotton Fabrics

Cotton fabrics for the standard artificial soiling recommended by JOCS are used for the treatment under conventional industrial conditions. Their properties, however, are different markedly from lot to lot owing to the finishing conditions. Accordingly, authors investigated the quality change of the fabrics during oxidative bleaching by sodium hypochlolite solution. The change of copper number and average polymerization degree (fluidity), as well as the tensile and tear strength of bleached fabrics were determined.Results obtained are as follows : 1) With the increases in copper number and/or fluidity of oxidized cellulose, the fabrics become to be easily soiled and the artificially soiled fabrics are easily desoiled as well.2) Copper number and fluidity of oxidized cellulose are intimately related to the tear and tensile strength. Chemical damage of the fabrics caused by bleaching can also be detected from these measurements.The authors found a clue to control the bleaching condition in order to supply standard cotton fabrics of constant properties.

Studies on the Oxidative Decomposition of Lignin

Peroxide materials (hydrogen and sodium peroxides) are now used very successfully in the bleaching of certain types of pulp such as ground wood or semichemical pulp. Peracetic acid is of obvious interest as an oxidative bleaching agent. A significant characteristic of peracetic acid is that the addition of this acid in the ordinary bleaching system results in increasing brightness, up to a high limit.A study of the rate of consumption by hard-wood chemical ground pulp of oxidants such as hydrogen and sodium-peroxides or peracetic acid indicated that peracetic acid is an effective bleaching agent for high yield pulp, and that the bleaching is highly effective at ordinary temperatures in short times.The delignification of the chemical ground pulp by sodium peroxide or peracetic acid was studied. Residual lignin present in the pulp was more rapidly degraded by peracetic acid than by sodium peroxide under the same conditions. It was also found that the open aromatic aldehyde (vanillin or syringaldehyde) -yielding moieties of residual lignin are more effectively attacked during bleaching of chemical ground pulp by the former than by latter.Peracetic acid lignin prepared from dioxane lignin, which was isolated from un-bleaching chemical ground pulp, possessed interesting qualities. It was partially water- or ether-soluble, and a high total phenolic hydroxyl and carboxyl and a low methoxyl content. Combined evidences from UV and IR absorption spectra of dioxane lignin and its degradation product by peracetic acid, and from potentiometric titration and elemental analysis data suggest the demethoxylation and the ring opening of aromatic nuclei in the lignin to muconic acid structures via catechol structural elements by peracetic acid. Syringyl nuclei of dioxane lignin was more preferentially degraded than guaiacyl nuclei of it during peracetic acid oxidation.To gain a better understanding the mechanism of pulp bleaching by peracetic acid, the chemical degradation by this agent of aromatic compounds structurally related to lignin was carried out. Products thus obtained were vanillin, vanillic acid, Protocatechualdehyde, 2-methoxy-p-hydroquinone, 2-methoxy-p-benzoquinone and muconic acid from vanillin, vanillyl alcohol, acetovanillone or guaiacylmethyl carbinol under the conditions of peracetic acid bleaching.

KINETICS OF LIGHT-INDUCED CYTOCHROME OXIDATION AND P840 BLEACHING IN GREEN PHOTOSYNTHETIC BACTERIA UNDER VARIOUS CONDITIONS.

KINETICS OF LIGHT-INDUCED CYTOCHROME OXIDATION AND P840 BLEACHING IN GREEN PHOTOSYNTHETIC BACTERIA UNDER VARIOUS CONDITIONS.

“Weak links” in polysaccharide chains as related to modified groups

AbstractCelluloses of different origin are hydrolyzed at different rates in acid medium both in fiber form (heterogeneous process) and in solution (homogeneous process). On the basis of measurements for well purified samples of commercial wood and cotton celluloses, molecularly dissolved in concentrated phosphoric acid, it was recently proposed that the fact that initial rates of hydrolysis are higher for wood cellulose than for cotton cellulose is largely related to inductive effects from modified (electrophilic) groups, e.g., carboxyls and carbonyls. Some of these groups are no doubt introduced during purification processes involving oxidative bleaching. It is possible that some of the modified groups are of native origin, but they are few (less than one modified group for 400 glucose units). The probable mechanisms for the influence on the rate of hydrolysis of modified groups, e.g., inductive and steric effects, rearrangements of the ring structure, are discussed in relation to the present knowledge of polysaccharide reactions. The concepts of inductive effects are supported by evidence from the hydrolysis of hemicelluloses and other polysaccharides containing uronic acid groups.

Spectral and redox properties of bacteriochlorophyll in its natural state

The behaviour of bacteriochlorophyll in its natural state with regard to oxidative bleaching, photobleaching and temperature bleaching was investigated. Reversible changes in absorption by the addition of oxidative and reductive agents, previously measured in organic solution, were also found to be present when bacteriochlorophyll is in its natural state in chromatophores of purple bacteria. Only the absorption band of longest wavelength in Rhodospirillum rubrum, Rhodopseudomonas spheroides and Chromatium could be bleached reversibly. Also a reversible shift in position of the 800-mμ absorption band in Rh. rubrum occurs while there are indications of a similar shift in the other species. At a potential of approximately 515 mV the difference spectrum obtained by addition of ferri-ferrocyanide mixtures to chromatophores of Rh. rubrum was similar to the difference spectrum obtained by Duysens by illumination of living bacteria. Additional bleaching experiments were done by heating and illumination of the chromatophore extracts. The present experiments may yield a link between the in vitro and in vivo phenomena obtained with chlorophyllous pigments.

Have you tried BECCO compounds? ... for OXIDATION BLEACHING CATALYTIC REACTIONS

RETURN TO ISSUEPREVAdvertisementNEXThave you tried BECCO compounds? ... for OXIDATION BLEACHING CATALYTIC REACTIONSCite this: Chem. Eng. News 1950, 28, 27, 2249Publication Date (Print):July 3, 1950Publication History Published online5 November 2010Published inissue 3 July 1950https://doi.org/10.1021/cen-v028n027.p2249Copyright © 1950 AMERICAN CHEMICAL SOCIETYArticle Views55Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (53 KB) SUBJECTS:Catalytic reactions,Oxidation Get e-Alerts