BICARBONATE ANION AND TAED AS ACTIVATORS IN PEROXIDE BLEACHING OF A MECHANICAL PULP
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Date
2019-09
Journal Title
Journal ISSN
Volume Title
Publisher
CELLULOSE CHEMISTRY AND TECHNOLOGY
Abstract
Earlier research demonstrated that the bicarbonate anion (HCO3
ā
) activated hydrogen peroxide and made it into an
effective bleaching agent for both chemical and mechanical pulps at pH ~ 8.5. The peroxide/bicarbonate treatment is
designated as a PB stage. It was also observed that in PB bleaching of chemithermomechanical pulps (CTMPs), a higher
initial pH resulted in more H2O2 being consumed and the achievement of a higher bleached brightness. This research
focused on using Na2CO3 instead of NaHCO3 to achieve a higher pH in PB bleaching of softwood CTMP. Further
activation of the H2O2 was obtained by the addition of N, N, Nā, Nā-tetraacetylethylenediamine (TAED). There was a
high peroxide residual when 3.0% H2O2 on pulp (oven-dried or OD basis) was used in a conventional alkaline peroxide
(P) stage. Sodium carbonate was added to the P stage effluent (with or without TAED), which was recycled and used to
pretreat unbleached pulp. A significant increase in brightness (~3 points) was obtained when the pretreated pulp was
regularly bleached with 3.0% H2O2 on pulp in a P stage
Description
Keywords
peroxide bleaching, mechanical pulp, hydrogen peroxide, peroxymonocarbonate anion, ACE: Energy and Environmental Sustainability, University of Energy & Natural Resources, Ghana, power