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Title
Substitution of sodium hydroxide with magnesium hydroxide as an alkali source in the peroxide bleaching of softwood TMP
Authors
Huiren Hu and Hongjie Zhang
Received
June 20, 2009
Published
Volume 43 Issue 7-8 July-August
Keywords
magnesium hydroxide, TMP, peroxide bleaching, anionic trash, conductivity, turbidity
Abstract
Softwood thermo-mechanical pulp (TMP) was subjected to peroxide bleaching, by substituting sodium hydroxide (NaOH) with magnesium hydroxide (Mg(OH) ) as an alkali source. The optical and physical 2 properties of the bleached pulps were compared, as well as the COD, anionic trash and the organic and inorganic compounds present in the bleaching effluent. The results showed that, at the same hydrogen peroxide charge, the bulk opacity of Mg(OH) -based bleached pulp increased obviously, while the amount of 2 anionic trash and COD in the bleaching effluent decreased significantly, compared with that observed during NaOH-based bleaching. Furthermore, the consumption of hydrogen peroxide decreased considerably during Mg(OH) -based TMP bleaching. However, the physical properties and brightness gain resulted from the 2 Mg(OH) -based process were comparable to or just slightly lower than those obtained by the NaOH-based 2 one.
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