Towards improvements of kraft pulp bleaching by additional treatments
2011 (English)In: 16th International Symposium on Wood, Fiber and Pulping Chemistry: Proceedings, ISWFPC, 2011, 699-704 p.Conference paper (Refereed)
During the last decade, many efforts have been made in pulp and paper industry to construct more effective, sustainable and environmentally friendly pulp bleaching sequences. In this work, enzymatic (laccase-mediator system, L), non-oxidative chemical (urea, U) and mechanical (PFI refining, R) treatments have been conducted, alone or in a combination, on unbleached eucalyptus kraft pulps to evaluate their bleaching effects and thus the further potential as additional treatment(s) on a conventional bleaching process. The pulps obtained were characterized in terms of kappa number, hexenuronic acid content, brightness and viscosity. Moreover, the lignin-carbohydrates complexes (LCCs) were fractionated and characterized concerning lignin content and carbohydrate composition and for 1HNMR and thioacidolysis-GC and -SEC analysis. It has been found that the effect of the L treatment was limited at delignification by a kappa number reduction of 0.8 units. The effects of the U treatment included delignification (1.4 kappa units), HexA removal (3 mol/g) and pulp brightening (3.4 ISO units). The refining darkened the pulp (3 ISO units) while the subsequent L or U treatment could bleached more than without the R stage. The delignification extent by all the treatments could be noticed also from the isolation yields of the LCC1 (glucan-lignin) fraction. Thioacidolysis-SEC analysis revealed the darkening mechanism of the R treatment and the delignification mechanisms of L and U treatment, showing that the L treatment removed more effectively the condensed parts of the lignin located at LCC2 (xylan-lignin) fraction.
Place, publisher, year, edition, pages
2011. 699-704 p.
, 16th International Symposium on Wood, Fiber and Pulping Chemistry - Proceedings, ISWFPC, 1
Bleaching, Eucalyptus, Laccase mediator system, Lignin-carbohydrate complex (LCC), Refining, Thioacidolysis, Urea, Additional treatment, Conventional bleaching, Environmentally-friendly, Eucalyptus kraft pulp, Hexenuronic acid, Kappa number reduction, Kappa numbers, Laccase mediator systems, Laccase-mediator system, Lignin contents, Lignin-carbohydrate complex, Non-oxidative, Pulp and paper industry, Pulp bleaching, SEC analysis, Carbohydrates, Cleaning, Delignification, Kraft process, Kraft pulp, Lignin, Metabolism, Pulp refining, Paper and pulp industry, Acidolysis, Laccase, Lignins, Pulp Industry
Paper, Pulp and Fiber Technology
IdentifiersURN: urn:nbn:se:kth:diva-149789ScopusID: 2-s2.0-84862924111OAI: oai:DiVA.org:kth-149789DiVA: diva2:741874
16th International Symposium on Wood, Fiber and Pulping Chemistry, ISWFPC; Tianjin, China; 8-10 June, 2011
QC 201408292014-08-292014-08-272014-08-29Bibliographically approved