Sökning: "oxygen bleaching"

Visar resultat 1 - 5 av 22 avhandlingar innehållade orden oxygen bleaching.

  1. 1. Optimization of Pretreatment of Kraft Pulp with Nitrogen Oxides

    Författare :Urban Öjteg; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Kappa number; lignins; Nitric acid; Magnesium; spent liquors; viscosity; softwood; oxygen bleaching; Nitrogen dioxide; Manganese; Oxygen; Nitrogen oxides; pretreatment; Kraft pulp;

    Sammanfattning : Modified kraft pulp subjected to oxygen bleaching following pretreatment with 2% nitrogen dioxide for 140 min with the addition of oxygen resulted in low selectivity after subsequent oxygen bleaching. In contrast, pretreatment in the absence of oxygen removed more than 80% of the lignin after oxygen bleaching and still maintained high selectivity (kappa number less than 5 at viscosity 950 dm3/kg). LÄS MER

  3. 2. Förbehandling av sulfatmassa och sulfatlignin med kväveoxider

    Författare :Urban Öjteg; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; delignifiering nitrogen dioxide; carbon dioxide; kraft pulps; pretreatment; bleaching; spent liquors; carboxylic acids; dinitrogen oxide; nitric acid; lignins; oxygen;

    Sammanfattning : .... LÄS MER

  4. 3. TCF Bleaching of Softwood Kraft Pulp. Metal Management Procedures

    Författare :Harald Brelid; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; bleaching; manganese; Kraft pulps; iron; copper; hydrogen peroxide; acid pretreatment; calcium; magnesium; liquid chromatography; ion exchange; metal complexes; EDTA;

    Sammanfattning : The aim of this work has been to increase knowledge of the influence of the metal ion content in softwood kraft pulp on peroxide bleaching and to investigate the effects of different metal management procedures at various stages in the production of TCF pulps (i.e. LÄS MER

  5. 4. Delignification and bleachability of kraft pulps pretreated with nitrogen dioxide

    Författare :Per Larsson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; chlorine dioxide; oxygen bleaching; molecular mass; paper properties; ozone bleaching; nitrogen dioxide; kraft pulps; pretreatment; gel permeation chromatography; indulin AT; hydrogen peroxide; consecutive alkaline extractions;

    Sammanfattning : .... LÄS MER

  7. 5. The link between kraft cooking and bleaching : influence on ECF bleachabiblity and bleaching effluent parameters

    Författare :Magnus Björklund; []
    Nyckelord :;

    Sammanfattning : The link between kraft cooking and bleaching was investigated, with the focus on how cooking kappa number, cooking conditions and pre-bleaching stages influence ECF bleachability and environmental parameters in the bleaching effluent. In one part of the study standard cooking conditions were used to produce birch and spruce pulps of different kappa numbers and then we studied how the AOX in the ECF bleaching effluent was affected by oxygen delignification, and hot acid stages. LÄS MER