Bleaching of softwood kraft pulps with H2O2, O3, and ClO2

NR 20140805
Ozone or chlorine dioxide bleaching prior to hydrogen peroxide bleaching greatly improves the performance of the hydrogen peroxide stage. The efficiency is further improved by a chelating treatment immediately after the ozone or chlorine dioxide stage. With an optimal metal ion profile, laboratory bleached (OAZQP) softwood kraft pulps can reach brightness levels above 90% ISO, with 5-10% lower pulp strength properties and bleaching costs comparable to ECF bleaching. It also is possible to obtain full brightness with only hydrogen peroxide provided the metal ion profile is optimal, e.g., by using multiple QP treatments. The chemical consumptions, expressed as oxidation equivalents per decreased kappa number are the same as for sequences including ozone or chlorine dioxide. Ozone and chlorine dioxide are comparable as far as delignification and brightness efficiency go.

By the author/editor: Axegard, Peter; Bergnor, Elisabe ...; Ek, Monica; Ekholm, Ulrika

About the subject

ENGINEERING AND TECHNOLOGY: ENGINEERING AND ...; and Chemical Enginee ...; and Polymer Technolo ...

NATURAL SCIENCES: NATURAL SCIENCES; and Chemical Science ...; and Polymer Chemistr ...

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