BICARBONATE ANION AND TAED AS ACTIVATORS IN PEROXIDE BLEACHING OF A MECHANICAL PULP

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Date
2019-09
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CELLULOSE CHEMISTRY AND TECHNOLOGY
Abstract
Earlier research demonstrated that the bicarbonate anion (HCO3 − ) 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, N’, N’-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
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peroxide bleaching, mechanical pulp, hydrogen peroxide, peroxymonocarbonate anion, ACE: Energy and Environmental Sustainability, University of Energy & Natural Resources, Ghana, power
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