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Troy M. Runge, Arthur J. Ragauskas

NMR Analysis of Oxidative Alkaline Extraction Stage Lignins

Chlorine dioxide delignified pulp was subjected to various oxidative alkaline extraction stages (EAr, E, EO, EP, and EPO) from which the residual and effluent lignins were isolated and characterized by ¹H and ¹³C NMR. Results of the NMR analyses indicate an increase in unconjugated carboxyl content of the lignins with the alkali treatment; a decrease in phenolic and formyl groups with oxidant reinforcement, especially oxygen; and an enrichment in aromatic methoxyl groups with increasing amount of oxidant reinforcement. The alkaline extracted pulps were further treated to a second chlorine dioxide stage from which the residual lignins were extracted and analyzed by ¹H NMR. Significant structural differences were noted between the various oxidative E stage and D₁ stage lignins.

Holzforschung, Walter de Gruyter

Print ISSN: 0018-3830
Volume: 53, 11/1999
Pages: 623 - 631

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