Oxidation of residual lignin with alkaline hydrogen peroxide. Part 1: Changes in hydrophilic groups
2000 (English)In: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 26, no 12, 448-454 p.Article in journal (Refereed) Published
Residual lignin was isolated from an oxygen-bleached softwood kraft pulp and subjected to oxidation with alkaline hydrogen peroxide in order to study how the degradation of the lignin is influenced by parameters such as time, temperature, addition of stabilizing agents and metal ions. The oxidized lignin samples were analyzed with respect to carboxyl and phenolic hydroxyl content. It was found that the peroxide treatment resulted in a rapid increase in the amount of carboxyl groups, presumably due to the elimination of chromophoric groups. Phenolic hydroxyl groups in the lignin required a higher temperature to be oxidized and this led to the formation of more carboxyl groups. The presence of DTPA and/or Mg (II) stabilized the hydrogen peroxide against decomposition and suppressed the degradation of phenolic groups, while the carboxyl groups remained the same. The addition of transition metal ions to the reaction system resulted in a rapid decomposition of hydrogen peroxide but also in a rapid formation of carboxyl groups and a degradation of the lignin.
Place, publisher, year, edition, pages
2000. Vol. 26, no 12, 448-454 p.
kraft pulps, oxygen bleaching, lignins, oxidation, hydrogen peroxide, degradation, parameters, carboxyl groups, hydroxyl groups, transition metals, free bleaching sequence, beta-guaiacyl-ether, model compounds, decomposition, iron, ion
IdentifiersURN: urn:nbn:se:kth:diva-20269ISI: 000166231700005OAI: oai:DiVA.org:kth-20269DiVA: diva2:338963
QC 201005252010-08-102010-08-10Bibliographically approved