title: Formation of carbonyl groups on cellulose during ozone treatment of pulp: consequences for pulp bleaching.
abstract: The formation of carbonyl groups during the ozone treatment (Z) of eucalyptus (Eucalyptus grandis and Eucalyptus urophylla hybrid) kraft pulps and their behaviors during subsequent alkaline stages were investigated by the CCOA method with carbazole-9-carboxylic acid [2-(2-aminooxethoxy)-ethoxy] amide (CCOA) as the carbonyl-selective fluorescence label. Several pulp samples with or without lignin and hexenuronic acids (hexA) were used to elucidate the effects of these components when present in unbleached kraft pulp. Both hexA and lignin increased the formation of carbonyl groups on cellulose and hemicellulose during ozonation. It was concluded that radicals are likely formed when ozone reacts with either lignin or hexA. These carbonyl groups were involved in cellulose depolymerization during subsequent alkaline extraction stages with sodium hydroxide (E) and alkaline hydrogen peroxide (P, in ZEP or ZP). Their numbers decreased after E but increased during P when H2O2 was not stabilized enough. Several ways to minimize the occurrence of carbonyl group formation are suggested.
authors.affiliation: Grenoble INP-Pagora, The International School of Paper Print Media and Biomaterials, 461 rue de la papeterie - CS 10065, 38402 St Martin d'Hères Cedex, France. Electronic address: Frederic.Pouyet@grenoble-inp.org.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Pouyet
authors.affiliation: Grenoble INP-Pagora, The International School of Paper Print Media and Biomaterials, 461 rue de la papeterie - CS 10065, 38402 St Martin d'Hères Cedex, France. Electronic address: Christine.Chirat@pagora.grenoble-inp.fr.
authors.forename: Christine
authors.initials: C
authors.lastname: Chirat
authors.affiliation: Christian Doppler Laboratory of Pulp Reactivity, Institute of Chemistry, University of Agricultural Sciences, Muthgasse 18, A-1190 Vienna, Austria. Electronic address: Antje.Potthast@boku.ac.at.
authors.forename: Antje
authors.initials: A
authors.lastname: Potthast
authors.affiliation: Grenoble INP-Pagora, The International School of Paper Print Media and Biomaterials, 461 rue de la papeterie - CS 10065, 38402 St Martin d'Hères Cedex, France. Electronic address: Dominique.Lachenal@pagora.grenoble-inp.fr.
authors.forename: Dominique
authors.initials: D
authors.lastname: Lachenal
mesh_terms: D000447:Aldehydes / Q000138:chemical synthesis; D057886:Bleaching Agents / Q000737:chemistry; D002264:Carboxylic Acids / Q000138:chemical synthesis; D002482:Cellulose / Q000737:chemistry*; D005052:Eucalyptus / Q000737:chemistry; D010126:Ozone / Q000737:chemistry*
chemical_list: D000447:Aldehydes; D057886:Bleaching Agents; D002264:Carboxylic Acids; D010126:Ozone; D002482:Cellulose
keywords: CCOA method; Carbonyl groups; Chlorine-free bleaching sequence; Ozone; Pulp bleaching