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Hellström, Pia
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Publications (3 of 3) Show all publications
Hellström, P. (2015). Fenton Pre-treatment of a Birch Kraft Pulp for MFC preparation. (Licentiate dissertation). Karlstad: Karlstads universitet
Open this publication in new window or tab >>Fenton Pre-treatment of a Birch Kraft Pulp for MFC preparation
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The potential to use acidic hydrogen peroxide in the presence of ferrous ions (Fenton’s reagent) as a pre-treatment when producing microfibrillar cellulose (MFC) from a fully bleached birch (Betula verucosa) kraft pulp was investigated and the properties of the produced MFC was compared to the properties of a MFC produced with enzymatic pre-treatment with a monocomponent endoglucanase (FiberCare® R). The mechanical treatment to MFC was performed in a laboratory colloid mill or in a pilot high-pressure homogeniser and the pre-treated pulps as well as the produced MFCs were chemically and morphologically characterised. Additionally, the MFCs produced in the colloid mill were evaluated as strength enhancers in test sheets representing the middle ply of paperboard.

From the chemical characterisation, it was concluded that the Fenton pre-treatment caused a decrease in the degree of polymerisation (DP) and an increase in both carboxyl- and carbonyl groups. The increase in carbonyl groups could not be explained by the formation of new reducing end groups due to depolymerisation which indicates that carbonyl groups are introduced along the cellulose chain. The enzymatic pre-treatment as performed in this study caused less impact on the cellulosic material, i.e. resulted in a pulp with a higher DP and a much lower amount of carbonyl- and carboxylic groups compared with the Fenton pre-treated pulps. In the subsequent mechanical treatment in a colloid mill, the Fenton pre-treated pulps were easier to process mechanically i.e. reached a higher specific surface area and a higher surface charge at a given mechanical treatment time compared to enzymatic pre-treated pulps and pulps not subjected to any pre-treatment. These findings were confirmed when MFCs were produced by homogenisation at high pressure in multiple passes; the birch kraft pulp was either pre-treated with Fenton’s reagent or the combined mechanic and enzymatic pre-treatment methodology used at the Centre Technique du Papier (CTP, France). By size fractionation, rheological measurements and scanning electron microscopy, it was revealed that Fenton pre-treatment resulted in MFC suspension containing a significantly higher proportion of small sized material (< 0.2 mm).

When the MFCs were evaluated as strength enhancers in test sheets produced from a furnish consisting of a spruce (Picea abies) chemithermomechanical pulp, MFC and a retention system containing cationic starch and an anionic silica sol, Fenton pre-treated MFCs increased the strength properties more than the enzymatic pre-treated MFCs. Addition of 5 wt% Fenton pre-treated MFC resulted in an increase in z-directional strength of about 50%, an increase in tensile stiffness index of about 25% and an increase in tensile index of 35% compared to test sheets prepared without MFC addition.

Abstract [en]

The potential to use acidic hydrogen peroxide in the presence of ferrous ions (Fenton’s reagent) as a pre-treatment when producing microfibrillar cellulose (MFC) from a bleached birch kraft pulp was investigated and the properties of the produced MFC was compared to the properties of a MFC produced with enzymatic pre-treatment. Additionally, the MFCs evaluated as strength enhancers in test sheets representing the middle ply of paperboard.

From the chemical characterisation, it was concluded that the Fenton pre-treatment caused a decrease in the degree of polymerisation (DP) and an increase in both carboxyl- and carbonyl groups. In the subsequent mechanical treatment in a colloid mill, the Fenton pre-treated pulps were easier to process mechanically indicating a potential to lower the energy consumption.

When the MFCs were evaluated as strength enhancers in test sheets, Fenton pre-treated MFCs increased the strength properties more than the enzymatic pre-treated MFCs at a given mechanical treatment time. Addition of 5 wt% Fenton pre-treated MFC resulted in an increase in z-directional strength of about 50%, an increase in tensile stiffness index of about 25% and an increase in tensile index of 35% compared to test sheets prepared without MFC addition.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2015
Series
Karlstad University Studies, ISSN 1403-8099 ; 2015:6
Keywords
Microfibrillated cellulose, Fenton chemistry, carbonyl groups, surface charge, total charge, Enzymatic hydrolysis, Tensile strength, z-directional strength
National Category
Natural Sciences
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-34770 (URN)978-91-7063-617-2 (ISBN)
Presentation
2015-02-05, 9C204, Karlstads universitet, Karlstad, 10:15 (Swedish)
Opponent
Supervisors
Available from: 2015-01-30 Created: 2014-12-12 Last updated: 2015-06-02Bibliographically approved
Walter, K., Paulsson, M. & Hellstrom, P. (2013). Acid Hydrogen Peroxide Treatment of Norway Spruce TMP: A Model Study Using Free Ferrous Ions and Ferric Ions Chelated with EDTA as Catalysts. Journal of wood chemistry and technology, 33(4), 267-285
Open this publication in new window or tab >>Acid Hydrogen Peroxide Treatment of Norway Spruce TMP: A Model Study Using Free Ferrous Ions and Ferric Ions Chelated with EDTA as Catalysts
2013 (English)In: Journal of wood chemistry and technology, ISSN 0277-3813, E-ISSN 1532-2319, Vol. 33, no 4, p. 267-285Article in journal (Refereed) Published
Abstract [en]

The acid hydrogen peroxide system has been evaluated in more detail in the presence of a coarse Norway spruce thermomechanical pulp (TMP). The effects of parameters on the reactions involved were determined, such as pH, retention time, pulp consistency, type of iron catalyst, and the amount of dissolved organic material. Residual hydrogen peroxide, chemical oxygen demand, dissolved iron, and total fiber charge were quantified and the hydroxyl radical activity was monitored. The results showed that a catalyst of free ferrous ions (Fe2+) gave more reactions with the lignocellulosic material than ferric ions (Fe3+) chelated with EDTA. Furthermore, there were somewhat more reactions with the TMP when there was less dissolved organic material in the liquid phase from the start. Hydroxyl radicals were detected in all cases, but the level differed depending on the conditions used. It is likely that the iron must bind with the TMP or be in close proximity for the hydroxyl radicals to react with the pulp.

Keywords
Hydrogen peroxide, TMP, Fenton's reagent, hydroxyl radicals, EDTA, COD, total fiber charge
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-38574 (URN)10.1080/02773813.2013.792840 (DOI)000320098800004 ()
Available from: 2015-11-30 Created: 2015-11-23 Last updated: 2017-12-01Bibliographically approved
Hellström, P., Heijnesson- Hultén, A., Paulsson, M., Håkansson, H. & Germgård, U. (2013). The effect of Fenton chemistry on the properties of microfibrillated cellulose (MFC).
Open this publication in new window or tab >>The effect of Fenton chemistry on the properties of microfibrillated cellulose (MFC)
Show others...
2013 (English)Other (Other academic)
Keywords
Fenton, microfibrillated cellulose
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-29181 (URN)
Available from: 2013-09-25 Created: 2013-09-25 Last updated: 2017-12-11Bibliographically approved
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