The final bleaching of eucalypt kraft pulps with hydrogen peroxide: relationship with industrial ECF bleaching history and cellulose degradation
authors Loureiro, PEG; Evtuguin, DV; Carvalho, MGVS
nationality International
journal JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
author keywords bleaching selectivity; brightness reversion; hydrogen peroxide decomposition; pulp bleachability; stabilizers
keywords CATALYTIC DECOMPOSITION; CHEMIMECHANICAL PULPS; METAL-IONS; MANGANESE; STABILITY; STABILIZATION; PERFORMANCE; CHEMISTRY; OXIDATION; RADICALS
abstract BACKGROUND: The process of chemical pulp bleaching is based for the most part in chlorine dioxide within elemental chlorine free (ECF) technologies. The use of greener alternatives such as bleaching with hydrogen peroxide (P stage) is not widely used owing to selectivity concerns related to transition metal-catalyzed decomposition reactions. Even at the final stage where peroxide is recognized to boost brightness and improve the brightness stability of the bleached pulp, cellulose degradation often overcomes these advantages. This paper presents the results of studies intended to optimize final peroxide bleaching performance considering two standard ECF industrial bleaching sequences: the conventional DED and the ECF-light OQ(PO) D (stages name: D - chlorine dioxide; E - alkaline extraction; O - oxygen; Q - chelation, (PO) - hydrogen peroxide pressurized with oxygen). RESULTS: The addition of sodium diethylenetriaminepentaacetate (DTPA) was the most effective option in terms of DED pulp bleachability and selectivity with hydrogen peroxide, as well as in terms of brightness reversion. As regards the OQ(PO)D pulp, a blend of DTPA and magnesium was the most beneficial in those properties. CONCLUSIONS: The choice of the best hydrogen peroxide stabilizer, among the different tested combinations of magnesium and chelants (EDTA and DTPA) studied, in terms of pulp bleachability, bleaching selectivity and brightness reversion is dependent on the impact of the previous bleaching stages on metallic nature and content. The pulp Mg/(Fe + Cu) ratio was highlighted as a process parameter controlling cellulose degradation in peroxide bleaching. (C) 2010 Society of Chemical Industry
publisher WILEY-BLACKWELL
issn 0268-2575
year published 2011
volume 86
issue 3
beginning page 381
ending page 390
digital object identifier (doi) 10.1002/jctb.2527
web of science category Biotechnology & Applied Microbiology; Chemistry, Multidisciplinary; Engineering, Environmental; Engineering, Chemical
subject category Biotechnology & Applied Microbiology; Chemistry; Engineering
unique article identifier WOS:000287259400008
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journal impact factor 2.587
5 year journal impact factor 2.734
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