Reductive degradation of residual chromophores in kraft pulp with sodium dithionite
authors Carreira, HJM; Loureiro, PEG; Carvalho, MGVS; Evtuguin, DV
nationality International
journal TAPPI JOURNAL
keywords RESONANCE RAMAN-SPECTROSCOPY; HEXENURONIC ACID; SULFITE; LIGNIN; IDENTIFICATION; KINETICS
abstract The focus of this study is the chemistry of reductive bleaching of kraft pulps with sodium dithionite. A set of model compounds mimicking quinone structures, residual lignin structures with conjugated carbonyl/carboxyl groups and muconic acid, among others, was reduced with sodium dithionite and monitored by ultraviolet-visible (UV-vis) spectroscopy. Depending on the chromophore models, either reductive or sulfonation reactions are thought to be responsible for the degradation. No reductive degradation of hexeneuronic acid (HexA) residues was detected, but unsaturated structures of unknown origin were eliminated from the xylan. Additionally, the potential of the reductive stage with either sodium dithionite or sodium borohydride was tested using an industrial pine kraft pulp bleached by OOZEDD sequence. This pulp, with a 88.8% ISO brightness ceiling, exhibited a brightness increase to 90 +/- 0.5% in the final reduction stage.
publisher TECH ASSOC PULP PAPER IND INC
issn 0734-1415
year published 2012
volume 11
issue 3
beginning page 59
ending page 67
web of science category Materials Science, Paper & Wood
subject category Materials Science
unique article identifier WOS:000313948200006
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journal impact factor 0.516
5 year journal impact factor 0.611
category normalized journal impact factor percentile 35.714
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