Browsing by Author "LUUKKONEN, ANTTI"

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    BICARBONATE ANION AND TAED AS ACTIVATORS IN PEROXIDE BLEACHING OF A MECHANICAL PULP
    (CELLULOSE CHEMISTRY AND TECHNOLOGY, 2019-09) FRANCIS, RAYMOND C.; LUUKKONEN, ANTTI; ATTIOGBE, FRANCIS K.
    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