Characterization of the Residual Kraft Pulp Lignin In Situ by Sulfite Treatments |
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| Authors: | Rallming Yang Yuan-Zong Lai |
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| Affiliation: | Department of Paper and Bioprocess Engineering , Empire State Paper Research Institute State University of New York, College of Environmental Science and Forestry , Syracuse, New York, USA |
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| Abstract: | Abstract The O2 delignification of kraft pulps from Norway spruce was shown having a significant impact on the reactivity of the residual pulp lignin as revealed from their responses to sulfite treatments at pH 7.5. A substantial higher ratio of lignin sulfonation to the phenolic hydroxyl group content of residual pulp lignin was observed for the O2 -delignified kraft pulps (～ 0.8) as compared to a value of ～ 0.3 for the unbleached samples and ～ 1 for the spruce wood lignin. Under the prevailing sulfite treatment conditions, the sulfonation would be largely attributed to the phenolic lignin component and the etherified structures containing an α -carbonyl or -unsaturated group. The contribution from the latter units, evaluated by a borohydride pretreatment of pulps prior to the sulfite treatment, can only account for approximately 15% of the sulfonation observed for the O2 -delignified sample. Thus, the nature of phenolic structures in the O2 -delignified pulps was more similar to that of the wood lignin than that of the kraft pulps. |
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| Keywords: | Carbonyl groups lignin analysis in situ neutral sulfite treatment O2 delignification residual kraft pulp lignin wood lignin |
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