Brightness development during mechanical pulp peroxide bleaching

Tiina Liitiä, Marjatta Ranua, P. Honkonen, Atte Mikkelson, Marjatta Kleen

Research output: Contribution to journalArticleScientificpeer-review


Reasons leading to the brightness ceiling in mechanical pulp peroxide bleaching were investigated with spruce thermomechanical pulp. During peroxide bleaching, new phenolic guaiacyl units, alpha-carbonyls and catechols were shown to be formed. All those are known precursors that can be converted to new coloured structures. High chemical charges, especially alkali, enhance formation of these precursors, and thereby limit brightness development. Contrary to the previously reported results on hardwood chemithermomechanical pulp, nitrogen pressurization had no beneficial effect on final brightness of spruce thermomechanical pulp, although it may slightly reduce formation of some colour precursors. The lower chromophore formation is probably obscured by the reduced lignin dissolution. During peroxide bleaching, naturally formed peracetic acid has no significant role in brightness development.
Original languageEnglish
Pages (from-to)91-97
Number of pages7
JournalJournal of Pulp and Paper Science
Issue number3-4
Publication statusPublished - 2010
MoE publication typeA1 Journal article-refereed

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