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Combination of alkaline and enzymatic treatments as a process for upgrading sisal paper-grade pulp to dissolving-grade pulp
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
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2010 (English)In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 101, no 19, 7416-7423 p.Article in journal (Refereed) Published
Abstract [en]

A sequence of treatments consisting of an initial xylanase treatment followed by cold alkaline extraction and a final endoglucanase treatment was investigated as a process for upgrading non-wood paper-grade pulps to dissolving-grade pulps for viscose production. Five commercial dried bleached non-wood soda/ AQ paper pulps, from flax, hemp, sisal, abaca, and jute, were studied for this purpose. Commercial dried bleached eucalyptus dissolving pulp was used as reference sample. Sisal pulp showed the highest improvement in Fock's reactivity, reaching levels nearly as high or even higher than that of eucalyptus dissolving pulp (65%), and a low hemicellulose content (3-4%) when was subjected to this sequence of treatments. The viscosity, however, decreased considerably. A uniform and narrow molecular weight distribution was observed by size exclusion chromatography. C-13 nuclear magnetic resonance spectroscopy and Raman microspectroscopy revealed that the cellulose structure consisted of cellulose I.

Place, publisher, year, edition, pages
2010. Vol. 101, no 19, 7416-7423 p.
Keyword [en]
Alkaline extraction, Dissolving-grade pulp, Enzymatic treatment, Paper-grade pulp, Non-wood fibers
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-26983DOI: 10.1016/j.biortech.2010.04.050ISI: 000279894400032PubMedID: 20493684Scopus ID: 2-s2.0-77957728796OAI: oai:DiVA.org:kth-26983DiVA: diva2:373629
Note

QC 20101201

Available from: 2010-12-01 Created: 2010-12-01 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Conversion of Wood and Non-wood Paper-grade Pulps to Dissolving-grade Pulps
Open this publication in new window or tab >>Conversion of Wood and Non-wood Paper-grade Pulps to Dissolving-grade Pulps
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Dissolving-grade pulps are commonly used for the production of cellulose derivatives and regenerated cellulose. To obtain products of high quality, these so-called "special" pulps must fulfill certain requirements, such as high cellulose content, low hemicellulose content, a uniform molecular weight distribution and high cellulose reactivity. Most, if not all, of the commercial dissolving pulps accomplish these demands to a certain extent. Nevertheless, achieving high cellulose accessibility as well as solvent and reagent reactivity is not an easy task due to the compact and complex structure presented by the cellulose.

In the first part of this work, three commercial monocomponent endoglucanases were investigated with the purpose of enhancing the cellulose accessibility and reactivity of a hardwood dissolving pulp. A monocomponent endoglucanase with a cellulose-binding domain (CBD) was shown to significantly improve the cellulose reactivity. The positive effect of this enzyme on dissolving-grade pulps was also observed on paper-grade pulps.

The main focus of the forest industry is the production of paper-grade pulps. Paper-grade pulps are mostly produced by the kraft process. In contrast, dissolving-grade pulps are produced by the sulfite and prehydrolysis kraft processes due to the high purity required for these pulps. The kraft process is known for being the most efficient process in terms of energy and chemical recovery, which makes the production costs of paper-grade pulps lower than those of sulfite dissolving-grade pulps. Besides, the production of dissolving pulps present, among others, higher capital and chemical costs than paper-grade pulps.

Therefore, the viability of converting paper-grade pulps into dissolving pulps is brought into a question. However, this task is not simple because paper-grade pulps contain a lower cellulose content and a higher hemicellulose content than dissolving pulps. They also present lower cellulose reactivity and an inhomogeneous molecular weight distribution. As a consequence, the second part of this work focused on the study of the feasibility of converting kraft pulps into dissolving pulps. Several sequences of treatments of hardwoods and non-wood pulps were investigated. The best sequence for each suitable pulp was developed, and the parameters involved were optimized. After several attempts, it was demonstrated that pulps from birch, eucalypt and sisal fulfill the requirements of a commercial dissolving pulp for the viscose process after being subjected to a sequence of treatments that included two commercial enzymes, a xylanase and a monocomponent endoglucanase, and alkali extraction steps.

 

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. 57 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2010:46
National Category
Wood Science
Identifiers
urn:nbn:se:kth:diva-26967 (URN)978-91-7415-777-2 (ISBN)
Public defence
2010-12-03, Sal F3, Lindstedtsvägen 26, KTH, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
QC 20101201Available from: 2010-12-01 Created: 2010-11-30 Last updated: 2010-12-01Bibliographically approved

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Larsson, Per Tomas

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