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  • 1.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ibarra, David
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Köpcke, Viviana
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Larsson, Per Tomas
    Jääskeläinen, Anna-Stiina
    Production of dissolving grade pulps from non-wood paper grade pulps using enzymatic and chemical pre-treatments for the viscose process2010Conference paper (Refereed)
    Abstract [en]

    Cellulose is the most abundant biorenewable material, constitutes an important polymer since it is used as raw material for several products, e.g.  Paper and board but also cellulose-based products which have many important applications in the pharmaceutical, textile, food and paint industries.  A raw material with high cellulose content and low content of hemicelluloses, residual lignin, extractives and minerals is required for the prodn. of these products, e.g.  Cotton and dissolving grade pulp are used.  However, the high cost prodn. of dissolving grade pulps has aroused the possibility of upgrading paper grade pulps into dissolving pulps by selective removal of hemicelluloses and subsequent activation of the pulps.  This study reports the feasibility to produce dissolving grade pulps from different pulps, i.e.  Non-wood paper grade pulps and conventional hardwood kraft pulps, employing enzymic and chem. pretreatments.  A monocomponent endoglucanase and a xylanase followed by alk. extn. were tested in order to increase the accessibility and reactivity of the cellulose pulp and decrease the hemicellulose content, resp.  An optimization of these treatments in terms of enzyme dosage, incubation time and a possible combination of them was investigated.  The treatment effects on reactivity according to Fock's method, viscosity, hemicellulose content and mol. wt. distribution, using size exclusion chromatog. (SEC), were analyzed.  The characterization of cellulose structure after the enzymic and chem. treatments was investigated by different techniques.

  • 2.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Köpcke, Viviana
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ibarra, David
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Larsson, Per Tomas
    Characterization of dissolving pulps produced from Kraft pulps2009Conference paper (Refereed)
  • 3.
    Ibarra, David
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Kopcke, Viviana
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Influence of a novel laboratory endoglucanase on the reactivity and accessibility of dissolving pulp2008In: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 2008Conference paper (Refereed)
    Abstract [en]

    Cellulose is the most abundant biorenewable material, constitutes an important polymer since it is used as raw material for several products, e.g. cellulose derivs. which have many important applications in the fiber, paper, membrane, polymer, and paints industries.  A raw material with high cellulose content is required for the prodn. of cellulose derivs., e.g. cotton and dissolving pulp are used.  Cellulose forms a network structure of fibrils and fibrilar aggregations.  Intermol. hydrogen bonds, dipole interactions, and van der Waals interactions bind the cellulose mols. intensively together.  The accessibility and reactivity of the cellulose in wood pulps to solvents and reactive agents is usually limited.  In this respect, different types of pre-treatments have been assayed to increase the reactivity of cellulose, among them the use of enzymes such as monocomponent cellulases and cellulase mixt.  In this work, was investigated the influence of a novel lab. enzyme, from Paenibacillus sp. Strain BP-23, on a com. dissolving pulp from Eucalyptus globulus, in terms of enzyme dosage and incubation time.  Evaluation of these parameters in terms of accessibility and reactivity, according to Fockxs method, were investigated.  Structural characterization and mol. wt. distribution were carried out using 13C-CP/MAS NMR (Cross-Polarisation Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonanse) and SEC (Size Exclusion Chromatog.), resp.

  • 4.
    Ibarra, David
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Köpcke, Viviana
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Behavior of different monocomponent endoglucanases on the accessibility and reactivity of dissolving-grade pulps for viscose process2010In: Enzyme and microbial technology, ISSN 0141-0229, E-ISSN 1879-0909, Vol. 47, p. 355-362Article in journal (Refereed)
    Abstract [en]

    Three different commercial monocomponent endoglucanases, with and without a cellulose-binding domain (CBD) and differences in their glycosidic hydrolysis mechanisms, were compared with respect to their ability to enhance the accessibility and reactivity of dissolving-grade pulps for viscose production. Hardwood (eucalyptus) and softwood (mixture of Norway spruce and Scots pine) commercial dried and never-dried bleached sulfite dissolving pulps were used for this purpose. The effects of the enzymatic treatments on pulps were studied by reactivity, according to Fock's method, and viscosity measurements, and recording of molecular weight distributions. Among the different assayed enzymes, endoglucanase with a CBD and an inverting hydrolysis mechanism was found to be the most effective in increasing the reactivity of both pulps. Simultaneously, the viscosity decreased, being more marked for softwood dissolving pulp. A narrower molecular weight distribution, with a great reduction in the amount of long-chain cellulose molecules was observed in both pulps, being more pronounced for softwood dissolving pulp. By contrast, endoglucanase without a CBD and a retaining hydrolysis mechanism showed a barley enhancement of the studied properties. The effects of the different endoglucanase treatments were more pronounced when never-dried dissolving pulps were used.

  • 5.
    Ibarra, David
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Köpcke, Viviana
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Exploring enzymatic treatments for the production of dissolving grade pulp from different wood and non-wood paper grade pulps2009In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 63, no 6, p. 721-730Article in journal (Refereed)
    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.

  • 6. Ibarra, David
    et al.
    Köpcke, Viviana
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Influence of a monocomponent endoglucanase on different fibre raw materials: Study of accessability and reactivity.2008In: 10th EWLP: European Workshop on Lignocellulosics and Pulp, 2008, p. 48-51Conference paper (Refereed)
  • 7.
    Ibarra, David
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Köpcke, Viviana
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Larsson, Per Tomas
    Jääskeläinen, Anna-Stiina
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Combination of alkaline and enzymatic treatments as a process for upgrading sisal paper-grade pulp to dissolving-grade pulp2010In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 101, no 19, p. 7416-7423Article in journal (Refereed)
    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.

  • 8. Kopcke, Viviana
    et al.
    Ibarra, David
    Larsson, Per Tomas
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Optimization of enzymatic and chemical treatments to use Eucalyptus kraft pulp as dissolving pulp2010In: Polymers from Renewable Resources, ISSN 2041-2479, Vol. 1, no 17, p. 34-Article in journal (Refereed)
  • 9.
    Köpcke, Viviana
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ibarra, David
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Increasing accessibility and reactivity of paper grade pulp by enzymatic treatment for use as dissolving pulp2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 4, p. 363-368Article in journal (Refereed)
    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.

  • 10.
    Köpcke, Viviana
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ibarra, David
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Study on the feasibility of converting kraft pulps into dissolving pulps: accessibility and reactivity2008Conference paper (Refereed)
    Abstract [en]

    For the prodn. of cellulose derivs. raw material contg. high cellulose and low hemicellulose content is required and today's industrial state of the art is to use dissolving pulps produced by sulphite process or prehydrolisis kraft.  This work, in contrast, focuses on the study of two different paper-grade kraft pulps from hardwood - birch and eucalyptus -- and the possibility to use it as raw material for the prodn. of cellulose derivs.  There have been different studies that focus their investigations mainly on the decrease of the hemicellulose content.  The aspects of accessibility and reactivity of cellulose towards solvents and reagents, however, are investigated far less although being key parameters when a homogenous substitution is desired for the prodn. of cellulose derivs. of high quality.  In order to accomplish the requirements of a com. dissolving pulp, the kraft pulps were subjected to different enzymic treatments using com. enzymes, xylanase and monocomponent endoglucanase.  Reactivity (Fock) was notably improved and the hemicellulose content decreased down to com. typical dissolving pulp values.  Further on, the structural characteristics of the pulps will be studied by means of 13C-CP/MAS NMR and size exclusion chromatog. (SEC).

  • 11. Köpcke, Viviana
    et al.
    Ibarra, David
    Larsson, Per Tomas
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Feasibility study on converting paper-grade pulps to dissolving-grade pulps2010Conference paper (Refereed)
  • 12.
    Köpcke, Viviana
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ibarra, David
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Larsson, Per Tomas
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Optimization of treatment sequences for the production of dissolving pulp from birch kraft pulp2010In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 25, no 1, p. 31-38Article in journal (Refereed)
    Abstract [en]

    As a continuation of our work, the viability of converting paper-grade kraft pulps into dissolving-grade pulps, for several raw materials, has been presented. It has been demonstrated that a combination of an enzymatic treatment using a commercial xylanase followed by alkali extraction resulted in an efficient hemicellulose removal. Furthermore, the cellulose reactivity could be enhanced by an additional enzymatic treatment using a commercial monocomponent endoglucanase. As a result, pulps with the characteristics of those of a commercial dissolving pulp, in terms of hemicellulose content and cellulose reactivity, were obtained. The viscosity of the treated pulps, however, was significantly affected by the treatments; they present lower values than those suitable for the production of cellulose derivatives and regenerated cellulose. The pulps, on the other hand, contained mostly cellulose II, which may also affect the process. Therefore, as a continuation of this work, an optimization of the sequences of treatments as well as a study of the parameters involved was performed in order to overcome the low viscosity values and the presence of cellulose II. After the optimization, it was observed that the xylanase treatment could be replaced by an alkali extraction step, the reaction time for the alkali treatment could be shortened, the viscosity could be increased and pulps containing cellulose I could be obtained. ;  In addition, the hemicellulose content and cellulose reactivity values remained in the range of those of a commercial dissolving-grade pulp.

  • 13.
    Köpcke, Viviana
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ibarra, David
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Larsson, Per Tomas
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Optimization of treatments for the conversion of eucalyptus kraft pulp to dissolving pulp2010In: Polymers from Renewable Resources, ISSN 2041-2479, Vol. 1, no 1Article in journal (Refereed)
  • 14.
    Li, Dongfang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ibarra, David
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Köpcke, Viviana
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Production of Dissolving Grade Pulps from Wood and Non-Wood Paper-Grade Pulps by Enzymatic and Chemical Pretreatments2012In: Functional Materials from Renewable Sources / [ed] Liebner, F., Rosenau, T., American Chemical Society (ACS), 2012, p. 167-189Chapter in book (Refereed)
    Abstract [en]

    A raw material with high cellulose content and low content of hemicelluloses, residual lignin, extractives and minerals is required for many important applications in the pharmaceutical, textile, food and paint industries i.e. cotton and dissolving grade pulp are used. However, the high costs for the production of dissolving grade pulps has triggered interest in upgrading paper-grade pulps into dissolving pulps by selective removal of hemicelluloses and subsequent activation of the pulps. This study reports the feasibility to produce dissolving grade pulps from different wood and non-wood paper-grade pulps employing enzymatic and chemical pre-treatments. The results were compared to those of commercial bleached dissolving pulps.

  • 15.
    Li, Dongfang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ibarra, David
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Köpcke, Vivianna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Production of Dissolving Grade Pulps from Wood and Non-wood Paper Grade Pulps Using Enzymatic and Chemical Pre-treatmentsManuscript (preprint) (Other academic)
    Abstract [en]

    Cellulose is the most abundant biorenewable material, constitutes an important polymer since it is used as raw material for several products, e.g. paper and board but also cellulose-based products which have many important applications in the pharmaceutical, textile, food and paint industries. A raw material with high cellulose content and low content of hemicelluloses, residual lignin, extractives and minerals is required for the production of these products, e.g. cotton and dissolving grade pulp are used. However, the high cost production of dissolving grade pulps has aroused the possibility of upgrading paper grade pulps into dissolving pulps by selective removal of hemicelluloses and subsequent activation of the pulps. This study reports the feasibility to produce dissolving grade pulps from different wood and non-wood paper grade pulps employing enzymatic and chemical pre-treatments. The results were compared to those of commercial bleached dissolving pulps.

1 - 15 of 15
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