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Towards a selective ozone bleaching stage by addition of organic oxygenates

Pulp & paper Canada, 1995-09, Vol.96 (9), p.49-53

Copyright Southam Business Communications, Inc. Sep 1995 ;ISSN: 0316-4004 ;EISSN: 1923-3515

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  • Title:
    Towards a selective ozone bleaching stage by addition of organic oxygenates
  • Author: Xu, J ; Cogo, E ; Briois, L ; Duprat, S ; Molinier, J ; Coste, C ; Kalck, P
  • Subjects: alcohols ; bleaching ; bleaching agents ; chemical reactions ; ozone ; Pulp bleaching ; softwood ; softwood kraft pulps ; tert-butyl alcohol ; wood pulp
  • Is Part Of: Pulp & paper Canada, 1995-09, Vol.96 (9), p.49-53
  • Description: Based on the foregoing observations, the tert-butyl alcohol effect cannot be because of a chemical action. That conclusion is consistent with the tert-butyl alcohol dosage by gas phase chromatography in the liquid phase before and after ozonation. Nevertheless, the observation of smaller gas bubbles during the ozonation with tert-butyl alcohol compared to the blank, turned our attention to the ozone transfer study [8]. Determination of the coefficient kl.a--which is a product of the ozone transfer factor by the exchange specific area--shows that tert-butyl alcohol brings this value from 6.210'Symbol not transcribed'-2 S'Symbol not transcribed'-1 in the blank to 13.810'Symbol not transcribed'-2 S'Symbol not transcribed'-1 at 0C and from 5.810'Symbol not transcribed'-2 S'Symbol not transcribed'-1 in the blank to 23.810'Symbol not transcribed'-2 S'Symbol not transcribed'-1 at 25C. At the same time, the ozone saturation concentration is slightly increased. Abstract: Instead of chlorinated agents, oxygen, ozone and hydrogen peroxide make up the new bleaching-sequence roots. In this research field, the reported investigations are devoted to ozone-stage improvements by adding organic oxygenates. Many alcohols and acids known as radical scavengers succeed in increasing ozone reactivity, efficiency and selectivity at low consistency. Among the tested additives, tert-butyl alcohol shows an outstanding effect due to its hydrodynamic role in the ozone transfer. Even if the tert-butyl alcohol concentration is reduced to a large extent, the ozone transfer rise involves better access to the lignin, and the efficiency and selectivity increase. Finally, the bleaching sequences OZEZP and EZEZP including the modified Z stage carried out with a reasonable ozone charge, manage to reach high brightness values with good carbohydrate protection.
  • Publisher: Westmount: Annex Publishing & Printing, Inc
  • Language: English
  • Identifier: ISSN: 0316-4004
    EISSN: 1923-3515
  • Source: AUTh Library subscriptions: ProQuest Central
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