Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Improvement on cellulose accessibility and reactivity of different wood pulps
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
2008 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [sv]

Cellulosans tillgänglighet och reaktivitet är nyckelparametrar vid framställning av regenererad cellulosa och cellulosaderivat. Det är välkänt att på grund av cellulosans kristallina struktur är tillgängligheten begränsad för lösningsmedel och olika reagens. Till exempel kan en inhomogen substitution av hydroxylgrupperna i cellulosakedjan resultera i cellulosaderivat av sämre kvalitet. Baserat på detta har en del av arbetet i denna studie fokuserat på att förbättra cellulosans tillgänglighet och reaktivitet genom att studera effekten av olika enzymatiska behandlingar med monokomponent endoglukanaser. Resultaten visar att närvaron av en cellulosabindande domän fyller en viktig funktion för att öka cellulosans reaktivitet, men strukturen för den katalytiska domänen visade sig ha den största inverkan på cellulosans tillgänglighet. I kompletterande studier har även effekten av en mekanisk förbehandling i kombination med enzymatisk behandling utvärderats. Kombinationen av förbehandlingarna resulterade i en positiv effekt, cellulosans reaktivitet kunde ökas i större omfattning.

I dag används huvudsakligen dissolvingmassor som råvara vid framställning av cellulosaregenerat och cellulosaderivat. Kraven för dessa s.k. specialmassor är högt cellulosainnehåll samt lågt hemicellulosa- respektive lignininnehåll. På grund av dessa specifika krav är produktionskostnaderna för dessa massor högre än konventionella sulfatmassor. Den andra delen av studien har därför fokuserat på möjligheten att använda dessa sulfatmassor som dissolvingmassa. Det har visats att kombinationen av enzymatiska behandlingar med monokomponent endoglukanas och xylanas följt av ett alkaliskt steg kan resultera i massor där kraven uppfylls med avseende på cellulosans reaktivitet, och cellulosa- respektive hemicellulosainnehåll.

Abstract [en]

The accessibility and reactivity of cellulose are key parameters on the manufacturing of cellulose derivatives and regenerated cellulose. It is well known that, due to the crystalline structure of cellulose, the accessibility of solvents and reagents is limited. For instance, an inhomogeneous substitution of the hydroxyl groups of the cellulose chain might lead to the production of derivatives of low quality. As a consequence, part of this work has focused on improving the accessibility and reactivity on cellulose by studying the effect of different monocomponent endoglucanases. It has been demonstrated that the presence of the cellulose-binding domain plays an important role on the enhancement of cellulose reactivity; however, the structure of the catalytic domain has been showed to have the highest influence on this parameter. Furthermore, the influence of mechanical treatment prior to enzymatic treatment has been examined. The combination of pretreatments showed a positive effect enhancing to a larger extent the cellulose reactivity.

Currently, dissolving-grade pulps are commonly used for the production of cellulose derivatives and regenerated cellulose. The requirements for these so-called “special pulps” are a high cellulose content and a low hemicelluloses and lignin content. As a result of these specific demands, the production costs of these pulps are higher than those of common kraft pulps. The second part of this work, therefore, has been focused on the study on the viability of converting kraft pulps into dissolving pulps. It has been demonstrated that the combination of enzymatic treatments using a monocomponent endoglucanase and a xylanase together with the addition of an alkaline step could fulfil the requirements of a commercial dissolving pulp in terms of cellulose reactivity and cellulose and hemicellulose content.

Place, publisher, year, edition, pages
Stockholm: KTH , 2008. , 27 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2008:43
Keyword [en]
cellulose, accessibility, reactivity, enzymatic treatment, mechanical treatment, chemical treatment, dissolving pulp, paper grade pulps
National Category
Wood Science
Identifiers
URN: urn:nbn:se:kth:diva-4792ISBN: 978-91-7178-985-3 (print)OAI: oai:DiVA.org:kth-4792DiVA: diva2:13984
Presentation
2008-06-05, STFI-salen, STFI-Packfors., KTH, Drottning Kristinas väg 61, Stockholm, 14:00
Supervisors
Note
QC 20101117Available from: 2008-06-03 Created: 2008-06-03 Last updated: 2010-11-17Bibliographically approved
List of papers
1. The effect of different monocomponent endoglucanases on cellulose accessibility in dissolving pulps
Open this publication in new window or tab >>The effect of different monocomponent endoglucanases on cellulose accessibility in dissolving pulps
(English)Manuscript (Other academic)
Keyword
accessibility, cellulose, reactivity, monocomponent endoglucanase, cellulose-binding domain, mechanical treatment, enzymatic treatment
National Category
Wood Science
Identifiers
urn:nbn:se:kth:diva-8613 (URN)
Note
QC 20101117Available from: 2008-06-03 Created: 2008-06-03 Last updated: 2010-11-17Bibliographically approved
2. Increasing accessibility and reactivity of paper grade pulp by enzymatic treatment for use as dissolving pulp
Open this publication in new window or tab >>Increasing accessibility and reactivity of paper grade pulp by enzymatic treatment for use as dissolving pulp
2008 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 4, 363-368 p.Article in journal (Refereed) Published
Abstract [en]

 In this study, the feasibility of using different kraft pulps as dissolving pulps for the viscose process was investigated. Two different bleached hardwood kraft pulps from eucalypt (Eucalyptus globulus) and birch (Betula pendula) were subjected to several enzymatic and chemical pretreatments in order to improve the accessibility and reactivity of the pulps and to reduce the hemicellulose content. Enzymatic treatments were carried out using a commercial monocomponent endoglucanase and a commercial xylanase. Chemical treatment consisted of an alkali extraction. The effects of these pretreatments on reactivity and viscosity were assayed. In both pulps, the endoglucanase enhanced the cellulose reactivity and reduced the viscosity. The sequential combination of xylanase and endoglucanase enhanced the positive effect of endoglucanase treatment alone for eucalypt but showed no major effect for birch. The addition of an alkali extraction step after the xylanase followed by endoglucanase treatment as a final step significantly reduced the hemicellulose content to 24% while the reactivity reached the value of a commercial dissolving pulp (65-70%). The viscosity, on the other hand, showed a considerably decrease.

Keyword
Hardwood, Kraft pulp, Dissolving pulp, Reactivity, Xylanase, Monocomponent endoglucanase, Alkali extraction
National Category
Wood Science
Identifiers
urn:nbn:se:kth:diva-8614 (URN)10.3183/NPPRJ-2008-23-04-p363-368 (DOI)000262102700002 ()2-s2.0-58149242427 (Scopus ID)
Note
QC 20100917. Uppdaterad från Manuskript till Artikel (20100917).Available from: 2008-06-03 Created: 2008-06-03 Last updated: 2017-12-14Bibliographically approved

Open Access in DiVA

fulltext(812 kB)2626 downloads
File information
File name FULLTEXT01.pdfFile size 812 kBChecksum MD5
b09b29ed76ef75710207bca8146a0b4d071f50895e67c47e717cb23c7a0739fa0dc082f9
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Köpcke, Viviana
By organisation
Wood Chemistry and Pulp Technology
Wood Science

Search outside of DiVA

GoogleGoogle Scholar
Total: 2626 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 743 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf