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Studies of lignin transformation in polyoxometalate (POM) bleaching of kraft pulpAuthor(s): Biljana Bujanovic; Richard S. Reiner; Kolby C. Hirth; Sally A. Ralph; Rajai H. Atalla
Source: Proceedings of the 59th APPITA annual conference and exhibition incorporating the 13th International Symposium on Wood, Fiber and Pulping Chemistry, 2005, May 16-19, Auckland, NZ. Auckland, NZ : Appita, 2005: pages 49-56
Publication Series: Miscellaneous Publication
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DescriptionIn order to elucidate changes occurring in lignin during polyoxometalate delignification of kraft pulp, residual lignins of a series of POM- delignified kraft pulps of decreasing kappa number were isolated and characterized. Oxidative treatment of commercial unbleached kraft pulp was performed using complex POM solutions containing the active [SiVW11O40]anion. For comparison, oxygen delignification of the same kraft pulp was also performed. It was observed that POM-delignification results in lignin which is more closely associated with carbohydrates/glucose, especially in the early phase of delignification. Residual lignin after POM treatment was characterized by lower phenolic hydroxyl group content than those of kraft and kraft oxygen-delignified pulp, which corroborates the preferential attack of POMs on the phenolic lignin units. The dominant lignin product identified in the POM solution after delignification was vanillin, which is an oxidation product of uncondensed G-units and indicates cleavage of Ca -Cb and/or aryl-ether bonds.
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CitationBujanovic, Biljana; Reiner, Richard S.; Hirth, Kolby C.; Ralph, Sally A.; Atalla, Rajai H. 2005. Studies of lignin transformation in polyoxometalate (POM) bleaching of kraft pulp. Proceedings of the 59th APPITA annual conference and exhibition incorporating the 13th International Symposium on Wood, Fiber and Pulping Chemistry, 2005, May 16-19, Auckland, NZ. Auckland, NZ : Appita, 2005: pages 49-56
KeywordsVanillin, polyoxometalates, sulphate pulping process, pulping, bleaching, oxidation, hydroxyl group, pulp and paper processes, delignification
- Structural changes of residual lignin of softwood and hardwood kraft pulp upon oxidative treatment with polyoxometalates
- Lignin modification in the initial phase of softwood kraft pulp delignification with polyoxometalates (POMs)
- Composition of the organic components in polyxometalate (POM) liquors from kraft pulp bleaching
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