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Title
Efficiency and effluent characteristics from Mg(OH)2-based peroxide bleaching of high-yield pulps and deinked pulp
Authors
Celine Leduc Joannie Martel and Claude Daneault
Received
January 18, 2010
Published
Volume 44 Issue 7-8 July-August
Keywords
bleaching, mechanical pulp, deinked pulp, magnesium hydroxide, efficiency, environment
Abstract
The present research project, devoted to peroxide bleaching, evaluated magnesium hydroxide [Mg(OH)] as 2 a substitute of sodium hydroxide [NaOH] for different mechanical pulps and deinked pulp. The analysis of the results obtained on both TMP and CTMP showed that the use of Mg(OH) as a substitute of NaOH in 2 peroxide bleaching allowed a reduction in both magnesium hydroxide and sodium silicate concentration, and a higher concentration of residual peroxide, which could be recirculated in the process. In deinked pulp, a significant reduction in Mg(OH) concentration was also achieved. The yield of the bleaching process was 2 improved by 1 to 2%, yet the final brightness level was slightly lower. Other benefits related to the effluent were observed, such as a significant reduction of the cationic demand and a decrease of some environmental parameters, e.g. the biochemical oxygen demand (BOD), the chemical oxygen demand (COD), the dissolved solids (DS) and the total organic carbon (TOC).
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