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Title: Polyoxometalate Delignification of Birch Kraft Pulp and Effect on Residual Lignin

Source: Journal of Wood Chemistry and Technology, Volume 31, Number 2,121-141, First published on: 03 May 2011 (iFirst) 2011

Author(s)Bujanovic, B.; Reiner, R.S.; Ralph, S.A.; Atalla, R.H.

Publication Year: 2011  View PDF »

Category: Journal Articles
Associated Research Project(s):   FPL-4709-3B

Abstract: To advance the understanding of delignification with polyoxometalates (POMs) that have been explored for use in bleaching of chemical pulps, the transformation of lignin during anaerobic treatment of birch kraft pulp with an equilibrated POM mixture composed of Na5(+2)[SiV1(-0.1)MoW10(+0.1)O40] was investigated. The conversion factor between the Klason lignin and the kappa number corrected for the hexenuronic acid (HexA) contribution gradually increased, indicating loss of lignin oxidizability. Comparative analysis of residual lignins isolated from pulps of decreasing kappa number showed that lignin undergoes changes that include a sharp reduction in the content of PhOH groups, a gradual demethylation, and a high increase in carbonyl groups. The results indicated that the POM treatment of kraft pulps leads to the loss of aromaticity, most likely caused by the conversion of aromatic rings to quinone moieties. The 2D NMR studies revealed the disappearance of the correlations assigned to stilbene structures formed during kraft pulping, and the weakening of those assigned to the native lignin bonds. The GPC studies showed a gradual lignin depolymerization.

Keywords: Chemical reactions; sulphate pulping process; polyoxometalates; lignin analysis; bleaching; pulping; carbonyl compounds; nuclear magnetic resonance; oxidation; quinone; stilbene; hydrolysis; gel permeation chromatography; fourier transform infrared spectroscopy; ultraviolet radiation; spectrum analysis; lignin; pulping; delignification; birch; hexenuronic acid; demethylation; depolymerization; GPC

Publication Review Process: Informally Refereed (Peer-Reviewed)

File size: 378 kb(s)

Date posted: 06/06/2011

This publication is also viewable on Treesearch:  view
RITS Product ID: 38028

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