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Exploring enzymatic treatments for the production of dissolving grade pulp from different wood and non-wood paper grade pulps
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
2009 (English)In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 63, no 6, 721-730 p.Article in journal (Refereed) Published
Abstract [en]

The feasibility of producing dissolving grade pulps for viscose production from different fiber raw materials, such as paper grade pulps from wood and non-woody plants, was investigated. Commercial dried bleached hardwood kraft pulps from eucalypt, and bleached non-wood soda/AQ pulps from flax, hemp, sisal, abaca, and jute, were subjected to enzymatic and chemical pretreatments in order to improve the accessibility and reactivity of cellulose and to reduce their hemicellulose content. A commercial monocomponent endoglucanase and a commercial xylanase were employed for biochemical treatment. The chemical treatment consisted of cold alkaline extraction. The effects of these pre-treatments on pulps were studied by reactivity, according to Fock's method, and viscosity measurements, determination of hemicellulose content, and recording of molecular weight distributions. The results were compared to those of commercial bleached eucalypt dissolving pulp. Eucalypt and sisal pulps showed high improvement in reactivity, reaching levels near or even higher than that of the eucalypt dissolving pulp (65%-70%), and a low hemicellulose content (2%-4%), when both were submitted to a sequence of treatments consisting of an initial xylanase treatment followed by cold alkaline extraction, and a final endoglucanase treatment. However, the viscosity decreased considerably. A uniform and narrow molecular weight distribution was observed in both eucalypt and sisal pulps after this sequential pre-treatment.

Place, publisher, year, edition, pages
2009. Vol. 63, no 6, 721-730 p.
Keyword [en]
dissolving grade pulp, endoglucanase, non-woody plants, paper grade, pulp, reactivity, regenerated cellulose, size exclusion chromatography, (SEC), viscose, wood, xylanase, kraft pulp, monocomponent endoglucanase, trichoderma cellulases, nitren, extraction, reactivity, enzymes, xylan, accessibility, cellulose, removal
National Category
Paper, Pulp and Fiber Technology
Identifiers
URN: urn:nbn:se:kth:diva-18944DOI: 10.1515/hf.2009.102ISI: 000271661600012Scopus ID: 2-s2.0-73449134861OAI: oai:DiVA.org:kth-18944DiVA: diva2:336991
Note
QC 20100525 10th European Workshop on Lignocellulosics and Pulp, Stockholm, SWEDEN, AUG 25-28, 2008Available from: 2010-08-05 Created: 2010-08-05 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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