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Improved hydrogen peroxide bleaching of mechanical pulps using carbon dioxide in combination with sodium and magnesium based alkali sources

L. Logenius ; P. Engstrand ; Anders Karlström (Institutionen för signaler och system, Reglerteknik) ; M. Paulsson
16th International Symposium on Wood, Fiber and Pulping Chemistry - Proceedings, ISWFPC Vol. 1 (2011), p. 741-745.
[Konferensbidrag, refereegranskat]

The pH-profile in the hydrogen peroxide bleaching stage of a Norway spruce thermomechanical pulp was levelled out by using carbon dioxide in combination with sodium or magnesium based alkali sources. Addition of carbon dioxide when magnesium hydroxide was used as the alkali source increased the pulp brightness with up to 1.5 brightness units when the bleaching was performed at 70 °C. When the temperature was increased from 70°C to 90 °C the brightness was increased with about two brightness units, addition of carbon dioxide increased it further. The residual hydrogen peroxide and the chemical oxygen demand (COD) levels were not affected as a consequence of the carbon dioxide addition. In the experiments where sodium hydroxide was used as the alkali source, addition of carbon dioxide lowered the pH that resulted in a decreased COD level, a slightly lower brightness level and, to some extent, an increased residual hydrogen peroxide level.

Nyckelord: Bleaching, Brightness, Carbon dioxide, COD, Hydrogen peroxide, Thermomechanical pulp

Denna post skapades 2012-11-15. Senast ändrad 2016-09-14.
CPL Pubid: 166133


Institutioner (Chalmers)

Institutionen för signaler och system, Reglerteknik (2005-2017)



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