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  • 1.
    Abächerli, A
    et al.
    International lignin institute, Switzerland.
    Gosselink, R
    Agrotechnology & Food Innovations, The Netherlands.
    Jong, E. de
    Agrotechnology & Food Innovations, The Netherlands.
    Baumberger, S
    French National Institute for Agricultural Research.
    Hortling, B
    KCL.
    Bonini, C
    USB.
    D'Auria, M
    USB.
    Zimbardi, F
    ENEA.
    Barisano, D
    ENEA.
    Duarte, J
    INETI.
    Sena-Martins, G
    INETI.
    Ribeiro, B
    INETI.
    Koukios, E
    NTUA.
    Koullas, D
    NTUA.
    Avgerinos, E
    NTUA.
    Vasile, C
    PPI.
    Cazacu, G
    PPI.
    Mathey, R
    Granit.
    Ghidoni, D
    Granit.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE).
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Quintus-Leino, P
    VTT.
    Piepponen, S
    VTT.
    Laine, A
    VTT.
    Koskinen, P
    VTT.
    Gravitis, J
    LSIWC.
    Suren, J
    Bakelite.
    Fasching, M
    Lenzing.
    Intermediary status of the round Robins in the eurolignin network2005Conference paper (Refereed)
  • 2. Ala-Kaila, K.
    et al.
    Li, Jiebing
    KTH, Superseded Departments, Pulp and Paper Technology.
    Gellerstedt, Göran
    KTH, Superseded Departments, Pulp and Paper Technology.
    Chemical character of the response of softwood kraft pulp towards industrial two-stage oxygen-alkali delignification2004In: Paperi ja puu, ISSN 0031-1243, Vol. 86, no 5, p. 353-358Article, review/survey (Refereed)
    Abstract [fi]

    The transient behavior of residual material affecting the kappa number of softwood kraft pulp (termed residual lignin), was tested experimentally step-wise in an industrial two-stage oxygen-alkali delignification process. The behavior was characterized by leaching the pulps and dividing the residual lignin into four different fractions to represent the wash loss fraction, the easily leachable fraction, the slowly leachable fraction and the stagnant fraction of the lignin in pulp. Further characterization was made regarding the chemical character of these fractions, i.e. residual lignin, extractives, hexenuronic acid, and other chemical structures that contribute to the kappa number of the pulps. The componential delignification response in the two oxygen-alkali reactors and the effects of the leaching operation were comprehensively assessed regarding the behavior of these different pulp components. The results were compared with results obtained earlier for birch kraft pulp originating from the same industrial process and treated using identical experimental procedures. Application: This study gives a new perspective with which to evaluate apparent and actual responses in industrial oxygen-alkali delignification of kraft pulps.

  • 3. Ala-Kaila, K.
    et al.
    Li, Jiebing
    KTH, Superseded Departments, Pulp and Paper Technology.
    Sevastyanova, O.
    Gellerstedt, Göran
    KTH, Superseded Departments, Pulp and Paper Technology.
    Apparent and actual delignification response in industrial oxygen-alkali delignification of birch kraft pulp2003In: TAPPI Journal, ISSN 0734-1415, Vol. 2, no 10, p. 23-27Article in journal (Refereed)
    Abstract [en]

    The time-dependent behavior of material that affects the kappa number of birch kraft pulp was experimentally tested in an industrial, two-stage, oxygen-alkali delignification process. The pulps were leached, and the leached material was divided into four different fractions: the wash loss fraction and the easily leachable, slowly leachable, and stagnant fractions. These fractions were further characterized according to their chemical natures, representing residual lignin, extractives, hexenuronic acids, and other chemical structures contributing to the kappa number of the pulps. The apparent and actual delignification responses in the two reactors and the effects of the leaching operation were thoroughly evaluated based on the behaviors to these different pulp components.

  • 4. Al-Dajani, W. W.
    et al.
    Gellerstedt, Göran
    KTH, Superseded Departments, Pulp and Paper Technology.
    On the isolation and structure of softwood residual lignins2002In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 17, no 2, p. 193-198Article in journal (Refereed)
    Abstract [en]

    Different softwood residual lignins were isolated by acid hydrolysis of kraft and soda Pulps. Complete isolation of lignin Could not be achieved in one hydrolysis step. The yield of lignin varied between 35 and 55%. A more acidic, second hydrolysis step was therefore necessary to isolate almost all the lignin remaining in the Pulp residue, giving a total lipin yield of 91%. Alkaline extraction of the pulp was almost as efficient as acid hydrolysis in isolating residual lignins. However, alkaline extraction gave less pure lignin fractions and there was a clear indication of the existence of lignin-carbohydrate bonds. Pine wood meal was acid-hydrolyzed in the same way as the pulps. After two-stage acid hydrolysis, the combined lignin yield was only 45% of the Klason lignin content, which means that native lignin is more difficult to isolate front wood than residual lignin front a chemical pulp. It is Concluded that the difficulty encountered in isolating residual lignin by acid hydrolysis is a problem of limited accessibility due to a complex carbohydrate network surrounding the lignin.

  • 5. Al-Dajani, W. W.
    et al.
    Gellerstedt, Göran
    KTH, Superseded Departments, Pulp and Paper Technology.
    The effect of polysulphide pre-treatment and cooking parameters on the chemical properties and TCF bleachability of alkaline pulps2001In: Pulp & paper Canada, ISSN 0316-4004, Vol. 102, no 8, p. 44-48Article in journal (Refereed)
    Abstract [en]

    The effect of pre-treating softwood chips with polysulphide on the chemical properties of the resulting pulp has been investigated. During subsequent pulping after such pre-treatment, high alkali content is maintained in the cooking liquor and, consequently, an unbleached pulp with a decreased amount of hexenuronic acid is obtained. As compared to other kraft pulps in this study, a polysulphide pre-treatment gives high cooking field, a high viscosity and brightness for the unbleached pulp and a pulp of good bleachability.

  • 6.
    Areskogh, Dimitri
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Investigation of the Molecular Weight Increase of Commercial Lignosulfonates by Laccase Catalysis2010In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 11, no 4, p. 904-910Article in journal (Refereed)
    Abstract [en]

    Lignosulfonates are by-products from the sulfite pulping process. During this process, lignin is liberated from pulp fibers through sulfonation and washed away. As a consequence, the lignosulfonate molecules contain both hydrophobic and hydrophilic moieties. Lignosulfonates are low-value products with limited performance and are used as such as binders, surfactants, and plasticizers in concrete. Lignosulfonates face strong competition from synthetic petroleum-based plasticizers with superior quality. Therefore, increasing the performance of lignosulfonates is desirable not only from a sustainability point of view but also to expand their usage. One important aspect that describes how well lignosulfonates can act as plasticizers is the molecular weight. In this paper, the molecular weight of four commercial lignosulfonates is increased through oxidation by two laccases without utilization of mediators. Different parameters to obtain maximal molecular weight increase were identified and the technical significance of the experiments is discussed.

  • 7.
    Areskogh, Dimitri
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Polymerization of lignosulohonates by laccase - from model studies to application evaluation trials2010In: Oxidative enzymes as sustainable industrial biocatalysts / [ed] G Feijoo and MT Moreira, 2010, p. 151-156Conference paper (Refereed)
  • 8.
    Areskogh, Dimitri
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Reaction mechanism of laccase-catalyzed polymerization of lignin revealed with model study2008In: 10th European workshop on lignocellulosics and pulp proceedings, 2008, p. 101-104Conference paper (Refereed)
  • 9.
    Areskogh, Dimitri
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Structural modification of commercial lignosulphonates through laccase catalysis and ozonolysis2010In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 32, no 3, p. 458-466Article in journal (Refereed)
    Abstract [en]

    Lignosulphonates are by-products from the sulphite pulping process, in which lignin is separated from cellulose by the addition of sulphonic acid groups to the alpha-position of lignin, thereby increasing the solubility of lignin in water. The predominant industrial utilisations of lignosulphonates are as dispersants, plasticisers and water-reducing agents in concrete preparation. The ability of lignosulphonates to function as a good plasticisers and water reducers is intimately linked with the purity of the lignosulphonate, its molecular weight and the number of charged groups present in the macromolecule. Currently, lignosulphonates are outrivaled by synthetic plasticisers termed superplasticisers due to their superior properties when used as additives to high-strength concrete. If lignosulphonates are to successfully compete with these superplasticisers, significant modifications are required. This paper describes a two-stage treatment of lignosulphonates in which the molecular weight is increased through laccase oxidation and carboxylic groups are introduced through ozonolysis. The technical significance of the results is also discussed.

  • 10.
    Areskogh, Dimitri
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Nousiainen, Paula
    University of Helsinki, Department of Chemistry.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Sipilä, Jussi
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Oxidative polymerisation of models for phenolic lignin end-groups by laccase2010In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 64, no 1, p. 21-34Article in journal (Refereed)
    Abstract [en]

    The redox enzyme laccase can lead to cross-linking of lignin molecules by oxidising phenolic end groups to resonance-stabilised radicals that can undergo radical coupling to form covalent bonds. This property has potential for many technical applications. However, laccase treatment can also lead to degradation. Experiments were performed with two laccases of different oxidation potential and pH and temperature optima. The predominant reaction following laccase oxidation is the formation of 5-5' and 4-O-5' bonds. If the 5-position is blocked, other reactions occur, including coupling of the 1-position and oxidation of the a-position, which aggravates cross-linking of different lignin molecules. The product profile generated by the two laccases is somewhat different, mainly because of the different pH rather than differences in enzyme activity. Reaction mechanisms and the technical and biological significance of the results are discussed.

  • 11.
    Areskogh, Dimitri
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Nousiainen, Paula
    University of Helsinki, Department of Chemistry.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Sipilä, Jussi
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Sulfonation of phenolic end groups in lignin directs laccase-initiated reactions towards cross-linking2010In: Industrial Biotechnology, ISSN 1550-9087, E-ISSN 1931-8421, Vol. 6, no 1, p. 50-59Article in journal (Refereed)
    Abstract [en]

    The effect of sulfonation of the a-carbon on model compounds representing phenolic end groups on lignin was studied with respect to the reactions initiated by oxidation of laccase, by mass spectrometry. Sulfonation seems to direct the reactions towards formation of 5-5´ and 4-O-5´ bonds, avoiding formation of 1-O-4´ bonds and oxidation of the a-carbon. This, in turn, will facilitate cross-linking reactions between lignin molecules. Sulfonation therefore has potential as an industrial pretreatment prior to laccase treatment for various wood-containing materials.

  • 12.
    Axelsson, Patrik
    et al.
    KTH, Superseded Departments, Pulp and Paper Technology.
    Gellerstedt, Göran
    KTH, Superseded Departments, Pulp and Paper Technology.
    Lindström, Mikael
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Condensation reactions of lignin during birch Kraft pulping as studied by thioacidolysis2004In: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 30, no 12, p. 317-322Article in journal (Refereed)
    Abstract [en]

    The influences of kappa number and ionic strength during birch kraft cooking on the extent of lignin condensation have been studied using thioacidolysis and size exclusion chromatography. Thioacidolysis degrades alkyl-aryl ether bonds in lignin while leaving carbon-carbon and diaryl-ether bonds relatively intact. Therefore, the lignin structures not cleaved during thioacidolysis can be considered as relatively stable and may account,, for example,for the slow residual phase delignification in the kraft cook and for differences in bleachability. It was shown that condensed lignin structures are formed in the residual lignin during birch kraft cooking. The relative amount of such structures increased with decreasing kappa number or with increasing sodium ion concentration in the cook. These structures were also found in a xylan-lignin complex isolated from a birch kraft pulp. The condensed structures were only partly reactive during oxygen delignification.

  • 13. Baumberger, Stephanie
    et al.
    Abaecherli, Alfred
    Fasching, Mario
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gosselink, Richard
    Hortling, Bo
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Saake, Bodo
    de Jong, Ed
    Molar mass determination of lignins by size-exclusion chromatography: towards standardisation of the method2007In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 61, no 4, p. 459-468Article in journal (Refereed)
    Abstract [en]

    The reactivity and physicochemical properties of lignins are partly governed by their molar mass distribution. The development of reliable standard methods for determination of the molar mass distribution is not only relevant for designing technical lignins for specific applications, but also for monitoring and elucidating delignification and pulping processes. Size-exclusion chromatography (SEC) offers many advantages, such as wide availability, short analysis time, low sample demand, and determination of molar mass distribution over a wide range. A collaborative study has been undertaken within the Eurolignin European thematic network to standardise SEC analysis of technical lignins. The high-molar-mass fraction of polydisperse lignins was shown to be the main source of intra- and interlaboratory variations, depending on the gel type, elution solvent, detection mode, and calculation strategy. The reliability of two widespread systems have been tested: one based on alkali and a hydrophilic gel (e.g., TSK Toyopearl gel) and the other based on THF as solvent and polystyrene-based gels (e.g., Styragel). A set of practical recommendations has been deduced.

  • 14.
    Brodin, Ida
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ernstsson, Marie
    YKI.
    Sjöholm, Elisabeth
    Innventia.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Oxidative stabilisation of kraft lignin for carbon fibre production2012In: Holzforschung, ISSN 0018-3830, Vol. 66, p. 141-147Article in journal (Refereed)
    Abstract [en]

    With the aim of investigating kraft lignin as a raw material for carbon fibre production, different lignins have been stabilised in air at conditions varied according to a full factorial experimental design. The lignins under examination were purified kraft lignin powders originating from birch, spruce/pine and Eucalyptus globules, as well as lignin fibres originating from birch with 5% poly(ethylene oxide) (PEO) added as a plasticiser. The influence of temperature, time and heating rate on yield and glass-transition temperature (Tg) was investigated. The highest yield was achieved after stabilisation at 280C during 2 h with a heating rate of 0.2C min-1. The Tg of all lignin powders was increased when stabilisation occurred under harsher conditions. X-ray photoelectron spectroscopy analysis (XPS) of both the outer surface and the cleaved cross-section of individual lignin/PEO fibres showed a clear gradient in the degree of chemical modification, with the major change occurring on the surface resulting in the appearance of a skin-core structure after stabilisation. The behaviour of the lignin fibres during stabilisation is similar to that of pitch-based fibres, indicating good possibilities for lignin as raw material for carbon fibre production.

  • 15.
    Brodin, Ida
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Gellerstedt, Göran L. F.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Sjöholm, E.
    Membrane separated Kraft lignin as feedstock for chemical products2008In: 2008 Nordic Wood Biorefinery Conference, NWBC 2008 - Proceedings, 2008, p. 194-Conference paper (Refereed)
  • 16.
    Brodin, Ida
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Sjöholm, Elisabeth
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Kraft lignin as feedstock for chemical products: The effects of membrane filtration2009In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 63, no 3, p. 290-297Article in journal (Refereed)
    Abstract [en]

    The use of technical lignins as feedstock for chemical products will require improvements in purity, molecular mass distribution, and thermal behavior. Therefore, industrial black liquors from kraft pulping of softwood (spruce/ pine) and hardwood (birch and Eucalyptus globulus) have been subjected to fractionation according to molecular mass by ceramic membranes. After acidification and isolation of the lignin fractions, a variety of analytical methods have been applied to help understand their structure - property relationships. From all types of lignin, the chemical and polymeric properties of fractions isolated from the membrane permeates were more homogeneous. This demonstrates that technical kraft lignins, irrespective of origin, may constitute an interesting feedstock for products, such as carbon fibers, adhesives, and phenol-based polymers.

  • 17.
    Brodin, Ida
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Sjöholm, Elisabeth
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    The behavior of kraft lignin during thermal treatment2010In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 87, no 1, p. 70-77Article in journal (Refereed)
    Abstract [en]

    Purified kraft lignin fractions from technical pulping liquors of softwood and hardwood have been subjected to step-wise analytical pyrolysis in the temperature interval 200-900 degrees C. The heterogenic structure of kraft lignin was revealed by the formation of pyrolysis products throughout the entire temperature interval although the majority of products were formed at 500-600 degrees C. Beyond 700 degrees C, no further pyrolysis products could be detected but a substantial portion of the lignin was shown to be converted into thermally stable products (char) not accessible by analytical pyrolysis. With pre-oxidation of the lignin with air at 250 degrees C prior to pyrolysis, a shift towards higher pyrolysis temperature was observed with a concomitant change in product composition. Thermal gravimetric analysis on such lignins also showed an improved stability against degradation. Methylation of the lignin prior to pyrolysis did not induce any significant changes in behavior, except for much lower T-g values.

  • 18. Cadena, Edith M.
    et al.
    Du, Xueyu
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Fillat, Amanda
    García-Ubasart, Jordi
    Vidal, Teresa
    Colom, Josep F.
    On hexenuronic acid (HexA) removal and mediator coupling to pulp fiber in the laccase/mediator treatment2011In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 102, no 4, p. 3911-3917Article in journal (Refereed)
    Abstract [en]

    Flax soda/AQ pulps were treated with different fungal laccase-mediator combinations followed by physical and chemical characterization of the pulps to obtain a thorough understanding of the laccase/mediator effects on hexenuronic acid (HexA) removal and the coupling of mediator onto pulps for fiber functionalization. Large differences were found and the presence of lauryl gallate (LG) during Trametes villosa laccase (TvL) treatment (TvL + LG) resulted in a much larger reduction of pulp-linked HexA than the combination of p-coumaric acid (PCA) and Pycnoporus cinnabarinus laccase (PcL). A major portion of LG became attached to the pulp as revealed by an increase in the kappa number and further confirmed by thioacidolysis and H-1 NMR analysis of solubilized pulp fractions. Additional experiments with other chemical pulps and isolated pulp xylan and lignin revealed that HexA seems to be the sole pulp component attacked by TvL + LG. As a substrate for TvL, the reaction preference order is PCA > HexA > LG.

  • 19. del Rio, Jose C.
    et al.
    Rencoret, Jorge
    Marques, Gisela
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Jimenez-Barbero, Jesus
    Martinez, Angel T.
    Gutierrez, Ana
    Structural Characterization of the Lignin from Jute (Corchorus capsularis) Fibers2009In: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 57, no 21, p. 10271-10281Article in journal (Refereed)
    Abstract [en]

    The structural characteristics of the lignin from jute (Corchorus capsularis) fibers, which are used for high-quality paper pulp production, were studied. The lignin content (13.3% Klason lignin) was high compared to other nonwoody bast fibers used for pulp production. The lignin structure was characterized by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), 2D-NMR, and thioacidolysis. Upon Py-GC/MS, jute fibers released predominantly products from syringylpropanoid units with the S/G ratio being 2.1 and a H/G/S composition of 2:33:65. 2D-NMR of the milled wood lignin (MWL) isolated from jute fibers showed a predominance of beta-O-4' aryl ether linkages (72% of total side chains), followed by beta-beta' resinol-type linkages (16% of total side chains) and lower amounts of beta-5' phenylcoumaran (4%) and beta-1' spirodienone-type (4%) linkages and cinnamyl end groups (4%). The high predominance of the S-lignin units, together with the high proportion of beta-O-4' aryl ether linkages, which are easily cleaved during alkaline cooking, are advantageous for pulping. On the other hand, a small percentage (ca. 4%) of the lignin side chain was found to be acetylated at the gamma-carbon, predominantly over syringyl units. The analysis of desulphurated thioacidolysis dimers provided additional information on the relative abundances of the various carbon-carbon and diaryl ether bonds and the type of units (syringyl or guaiacyl) involved in each of the above linkage types. Interestingly, the major part of the beta-beta' dimers included two syringyl units, indicating that most of the beta-beta' substructures identified in the HSQC spectra were of the syringaresinol type (pinoresinol being absent), as already observed in the lignin of other angiosperms.

  • 20.
    Du, Xueyu
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Universal fractionation of lignin-carbohydrate complexes (LCCs) from lignocellulosic biomass: an example using spruce wood2013In: The Plant Journal, ISSN 0960-7412, E-ISSN 1365-313X, Vol. 74, no 2, p. 328-338Article in journal (Refereed)
    Abstract [en]

    It is of both theoretical and practical importance to develop a universally applicable approach for the fractionation and sensitive lignin characterization of lignin-carbohydrate complexes (LCCs) from all types of lignocellulosic biomass, both natively and after various types of processing. In the present study, a previously reported fractionation approach that is applicable for eucalyptus (hardwood) and flax (non-wood) was further improved by introducing an additional step of barium hydroxide precipitation to isolate the mannan-enriched LCC (glucomannan-lignin, GML), in order to suit softwood species as well. Spruce wood was used as the softwood sample. As indicated by the recovery yield and composition analysis, all of the lignin was recovered in three LCC fractions: a glucan-enriched fraction (glucan-lignin, GL), a mannan-enriched fraction (GML) and a xylan-enriched fraction (xylan-lignin, XL). All of the LCCs had high molecular masses and were insoluble or barely soluble in a dioxane/water solution. Carbohydrate and lignin signals were observed in H-1 NMR, C-13 CP-MAS NMR and normal- or high-sensitivity 2D HSQC NMR analyses. The carbohydrate and lignin constituents in each LCC fraction are therefore believed to be chemically bonded rather than physically mixed with one another. The three LCC fractions were found to be distinctly different from each other in terms of their lignin structures, as revealed by highly sensitive analyses by thioacidolysis-GC, thioacidolysis-SEC and pyrolysis-GC.

  • 21.
    Du, Xueyu
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    STRUCTURAL VERIFICATION OF LIGNIN-CARBOHYDRATE COMPLEX (LCC) STRUCTURES FROM SOFTWOOD FIBRES2010In: RESEARCH PROGRESS IN PAPER INDUSTRY AND BIOREFINERY (4TH ISETPP), VOLS 1-3 / [ed] Sun RC; Fu SY, GUANGZHOU: SOUTH CHINA UNIV TECHNOLOGY PRESS , 2010, p. 332-335Conference paper (Refereed)
    Abstract [en]

    The LCC fractionation process developed earlier by us for hardwood samples has been further improved to include an additional fractionation of glucomannan-lignin by a step of Ba(OH)(2) precipitation to suit softwood species better. Glucan-Lignin, Glucomannan-Lignin and Xylan-Lignin were thus obtained from spruce wood and subjected to SEC and NMR analysis and thioacidolysis followed by GC and SEC analysis respectively for structural elucidations. The LCC structures have been finally verified by comparisons with the LCC fractions prepared by another earlier developed softwood process.

  • 22.
    Du, Xueyu
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Rencoret, Jorge
    Instituto de Recursos Naturales y Agrobiologia de Sevilla.
    Del Rio, Jose C.
    Instituto de Recursos Naturales y Agrobiologia de Sevilla.
    Martinez, Angel
    Centro de Investigaciones Biologicas.
    Gutierrez, Ana
    Instituto de Recursos Naturales y Agrobiologia de Sevilla.
    Understanding Pulp Delignification by Laccase-Mediator Systems through Isolation and Characterization of Lignin-Carbohydrate Complexes2013In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 14, no 9, p. 3073-3080Article in journal (Refereed)
    Abstract [en]

    The effects and mechanism of pulp delignificabon by laccases in the presence of redox mediators have been investigated on unbleached eucalyptus kraft pulp treated with laccases from Pycnoporus cinnabarinus (PcL) and Myceliophthora thermophila (MtL) and 1-hydroxybenzotriazole (HBT) and methyl syringate (MeS) as mediators, respectively. Determination of the corrected kappa number in eucalyptus pulps after the enzymatic treatments revealed that the PcL-HBT system exhibited a more remarkable delignification effect than the MtL-MeS system. To obtain further insight, lignin-carbohydrate complexes were fractionated and subsequently characterized by nuclear magnetic resonance, thioacidolysis (followed by gas chromatography and size exclusion chromatography), and pyrolysis-gas chromatography-mass spectrometry (pyrolysis-GC-MS) analyses before and after the enzymatic treatments and their controls. We can conclude that the laccase mediator treatments altered the lignin structures in such a way that more lignin was recovered in the xylan-lignin fractions, as shown by Klason lignin estimation, with smaller amounts of both syringyl (5) and guaiacyl (G) uncondensed units, as shown by thioacidolysis and gas chromatography, especially after the PcL-HBT treatment. The laccase mediator treatment produced oxidation at C alpha and cleavage of C alpha and C beta bonds in pulp lignin, as shown by pyrolysis-GC-MS. The general mechanism of residual lignin degradation in the pulp by laccase-mediator treatments is discussed in light of the results obtained.

  • 23.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gellerstedt, GöranKTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.Henriksson, GunnarKTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Paper chemistry and technology2009Collection (editor) (Refereed)
    Abstract [en]

    The production of forestry products is based on a complex chain of knowledge in which the biological material wood with all its natural variability is converted into a variety of fiber-based products, each one with its detailed and specific quality requirements. This four volume set covers the entire spectrum of pulp and paper chemistry and technology from starting material to processes and products including market demands. Supported by a grant from the Ljungberg Foundation, the Editors at the Royal Institute of Technology, Stockholm, Sweden coordinated over 30 authors from university and industry to create this comprehensive overview. This work is essential for all students of wood science and a useful reference for those working in the pulp and paper industry or on the chemistry of renewable resources.

  • 24.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gellerstedt, GöranKTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.Henriksson, GunnarKTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Paper products physics and technology2009Collection (editor) (Refereed)
  • 25.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gellerstedt, GöranKTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.Henriksson, GunnarKTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Pulping chemistry and technology2009Collection (editor) (Refereed)
    Abstract [en]

    The production of forestry products is based on a complex chain of knowledge in which the biological material wood with all its natural variability is converted into a variety of fiber-based products, each one with its detailed and specific quality requirements. This four volume set covers the entire spectrum of pulp and paper chemistry and technology from starting material to processes and products including market demands. Supported by a grant from the Ljungberg Foundation, the Editors at the Royal Institute of Technology, Stockholm, Sweden coordinated over 30 authors from university and industry to create this comprehensive overview. This work is essential for all students of wood science and a useful reference for those working in the pulp and paper industry or on the chemistry of renewable resources.

  • 26.
    Ekevåg, Per
    et al.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Lindström, Tom
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Gellerstedt, Göran
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Lindström, Mikael
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Addition of carboxymethylcellulose to the kraft cook2004In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 19, no 2, p. 200-207Article in journal (Refereed)
    Abstract [en]

    The physical attachment of carboxymethylcellulose (CMC) onto kraft pulps during cooking and the effects of subsequent bleaching in an OD(EOP)DD sequence were investigated. Two CMC grades with different molecular weights and different degrees of substitution (D.S.) were used, CMC Finnfix WRH and CMC Cekol DVG. The effect of the CMC was studied by measuring the increase in the total charge density as well as in the surface charge density. In this way, both the total amount of attached CMC and the amount of the CMC attached onto the surface of the fibres Could be determined. Hand-sheets were made to study the effects of CMC addition on the physical properties of the paper. Different amounts of CMC were added to find the optimum, which was determined to be 1% CMC on wood. The proportion of CMC attached at a level addition of 1% (on wood) was about 40%. It was, however, found that a large part of the CMC was degraded during the cook. Whereas high molecular weight CMC is attached onto the surface of fibres, the degraded CMC is attached to the interior of the cell wall, decreasing the efficiency of the CIVIC to enhance the joint strength between fibres. The tensile index increased significantly, approximately 10% after beating to 2000 PFI revolutions, when 1% CMC Finnfix WRH on wood was added. The CMC Cekol DVG grade showed the greatest increase in tensile index, approximately 12% at 2000 PFI revolutions. The results of the bleaching of a sample treated with CMC Finnfix WRH showed that a part of the effect of CMC remains after bleaching. Most of the reduction in the positive effect was due to a loss of CMC molecules from the fibre surface.

  • 27. Elsander, A.
    et al.
    Ek, Monica
    KTH, Superseded Departments, Pulp and Paper Technology.
    Gellerstedt, Göran
    KTH, Superseded Departments, Pulp and Paper Technology.
    Oxalic acid formation during ECF and TCF bleaching of kraft pulp2000In: TAPPI Journal, ISSN 0734-1415, Vol. 83, no 2, p. 73-77Article in journal (Refereed)
    Abstract [en]

    Formation of oxalic acid during bleaching of softwood kraft pulp was studied. The bleaching agents used were oxygen, hydrogen peroxide, chlorine dioxide, peracetic acid, and ozone. Formation of oxalic acid increased linearly with the reduction in kappa number. However, bleaching with peracetic acid produced less oxalic acid than the other bleaching agents. In ozone bleaching, about one-third of the oxalic acid formed is adsorbed on the pulp and not released until pulp pH is increased during a later stage, where it could combine with calcium ions to produce a calcium oxalate scale.

  • 28.
    Forsström, A
    et al.
    Eka Chemicals, Sweden.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Jour, P
    Eka Chemicals, Sweden.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    On selective removal of hexenuronic acid (HexA) by oxidative bleaching of eucalyptus O2-delignified kraft pulp2005Conference paper (Refereed)
  • 29. Gartner, A.
    et al.
    Gellerstedt, Göran
    KTH, Superseded Departments, Pulp and Paper Technology.
    Oxidation of residual lignin with alkaline hydrogen peroxide. Part 1: Changes in hydrophilic groups2000In: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 26, no 12, p. 448-454Article in journal (Refereed)
    Abstract [en]

    Residual lignin was isolated from an oxygen-bleached softwood kraft pulp and subjected to oxidation with alkaline hydrogen peroxide in order to study how the degradation of the lignin is influenced by parameters such as time, temperature, addition of stabilizing agents and metal ions. The oxidized lignin samples were analyzed with respect to carboxyl and phenolic hydroxyl content. It was found that the peroxide treatment resulted in a rapid increase in the amount of carboxyl groups, presumably due to the elimination of chromophoric groups. Phenolic hydroxyl groups in the lignin required a higher temperature to be oxidized and this led to the formation of more carboxyl groups. The presence of DTPA and/or Mg (II) stabilized the hydrogen peroxide against decomposition and suppressed the degradation of phenolic groups, while the carboxyl groups remained the same. The addition of transition metal ions to the reaction system resulted in a rapid decomposition of hydrogen peroxide but also in a rapid formation of carboxyl groups and a degradation of the lignin.

  • 30. Gartner, A.
    et al.
    Gellerstedt, Göran
    KTH, Superseded Departments, Pulp and Paper Technology.
    Oxidation of residual lignin with alkaline hydrogen peroxide. Part II: Elimination of chromophoric groups2001In: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 27, no 7, p. 244-248Article in journal (Refereed)
    Abstract [en]

    Isolated residual lignin from art oxygen-bleached kraft pulp was subjected to oxidation with alkaline hydrogen peroxide under different time and temperature conditions in both the absence and presence of stabilizing agents and transition metal ions. The resulting lignin samples were analyzed by UV/VIS and FTIR spectroscopy. The analyses demonstrate the occurrence at a temperature as low as 50 degreesC: of a rapid but limited elimination of chromophoric groups, resulting in the formation of carboxyl groups. The presence of DTPA and magnesium ions stabilizes the hydrogen peroxide towards decomposition and the chromophore elimination is improved. At a higher oxidation temperature, 80 degreesC, the effect of added stabilizer(s) is particularly pronounced. Addition of transition metal ions resulted in a rapid decomposition of hydrogen peroxide and the introduction of new chromophoric groups.

  • 31.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Analytical methods2009In: Wood Chemistry and Wood Biotechnology, Walter de Gruyter, 2009, p. 195-217Chapter in book (Refereed)
  • 32.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Cellulose products and chemicals from wood2009In: Wood Chemistry and Biotechnology, Walter de Gruyter, 2009, p. 173-193Chapter in book (Refereed)
  • 33.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Chemistry of bleaching of chemical pulp2009In: Pulping Chemistry and Technology, Walter de Gruyter, 2009, p. 201-238Chapter in book (Refereed)
  • 34.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Chemistry of chemical pulping2009In: Pulping Chemistry and Technology, Walter de Gruyter, 2009, p. 91-120Chapter in book (Refereed)
  • 35.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Mechanical pulping chemistry2009In: Pulping Chemistry and Technology, Walter de Gruyter, 2009, p. 35-56Chapter in book (Refereed)
  • 36.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    On the importance of lignin-carbohydrate complexes in wood and chemical pulps2006In: Research Progress in Pulping and Papermaking, 2006 / [ed] Beihai, H; Shiya, F; Fangeng, C, 2006, p. 7-10Conference paper (Refereed)
    Abstract [en]

    Selective enzymatic hydrolysis of cellulose has been used to facilitate the isolation of lignin-carbohydrate complexes from wood and kraft pulps. On isolated fractions, a combination of thioacidolysis and size exclusion chromatography was used to gain information about the structure and chemical changes taking place in the lignin component when going from wood to kraft pulp. The method has been applied to spruce, birch and eucalyptus. For the hardwoods, however, the method needs improvement.

  • 37.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Professor Gosta Brunow (1936-2013) Obituary2014In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 68, no 2, p. 253-254Article in journal (Refereed)
  • 38.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Softwood kraft lignin: Raw material for the future2015In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 77, p. 845-854Article in journal (Refereed)
    Abstract [en]

    Large quantities of kraft lignin are formed in the pulp industry. Although the vast majority is used for internal energy production at mill sites, modern pulping technology allows for a partial outtake of lignin without disturbance of the energy balance in the mill. At present, lignin from softwood pulping is available in commercial quantities and it can be assumed that this amount will rapidly increase in the future. Therefore, development of material systems based on softwood kraft lignin should be beneficial for the future sustainable society and add value to a renewable resource. In this review, the formation, structure, and properties of softwood kraft lignin is summarized and it is suggested that, depending on final use, an optimization of lignin properties is done through selected fractionation and purification.

  • 39.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    The Wood-Based Biorefinery: A New Concept for Green Chemicals and Materials2008In: PROCEEDINGS OF INTERNATIONAL CONFERENCE ON PULPING, PAPERMAKING AND BIOTECHNOLOGY 2008: ICPPB '08, VOL I / [ed] Jin Y; Zhai H; Li Z, NANJING: NANJING FORESTRY UNIV , 2008, p. 9-15Conference paper (Refereed)
    Abstract [en]

    The rapid expansion of bioethanol production will, in addition to fermentation of sugar and starch sources, also involve a conversion of lignocellulosic materials. In addition to fermentable hexoses from cellulose and glucomannan, this will result in large amounts of lignin and xylan which can be used as process fuel but also serve as feedstock for chemicals and materials. Modem kraft mills constitute a second source of such products since the energy balance is such that a partial outtake from the black liquor can be permitted. Irrespective of source, lignin and xylan must be further purified/modified in order to acquire properties which make them suitable as feedstock in material systems.

  • 40.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    The worldwide wood resource2009In: Wood Chemistry and Biotechnology, Walter de Gruyter, 2009, p. 1-12Chapter in book (Refereed)
  • 41.
    Gellerstedt, Göran
    et al.
    KTH, Superseded Departments, Pulp and Paper Technology.
    Al-Dajani, W. W.
    Bleachability of alkaline pulps - Part 1. The importance of beta-aryl ether linkages in lignin2000In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 54, no 6, p. 609-617Article in journal (Refereed)
    Abstract [en]

    Analytical and structural studies were done on different types of alkaline pulps and their isolated residual lignins. Although having the same degree of delignification after cooking, some pulps were easier to bleach than others. All isolated residual lignins were found to contain beta -aryl ether (beta -O-4) structures in reasonable amounts when analysed by thioacidolysis (greater than or equal to 10% of the native lignin value). At decreasing kappa numbers, there was also a corresponding decrease in the amount of beta -aryl ether structures in the residual lignin. Moreover, a high beta -aryl ether content in the unbleached residual lignin after cooking was found to contribute to a better bleachability of the pulp, especially when hydrogen peroxide stages were involved. At the same degree of delignification, the superior bleachability of alkaline sulfite pulps over kraft pulps was shown to be attributable to a higher content of beta -aryl ether linkages in the further type of pulps.

  • 42.
    Gellerstedt, Göran
    et al.
    KTH, Superseded Departments, Pulp and Paper Technology.
    Al-Dajani, W. W.
    Some factors affecting the brightness and TCF-bleachability of kraft pulp2003In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 18, no 1, p. 56-62Article in journal (Refereed)
    Abstract [en]

    By varying the cooking conditions, several series of kraft pulps having different brightness levels, i.e. different light absorption coefficients (k), were prepared. A clear correlation between the residual alkali concentration in the black liquor and the k-value was found. The darkening of the pulp (increasing k) was shown to be, in part, due to a higher content of calcium ions that increased lignin redeposition onto the fibers during the cook. Moreover, the production of a bright unbleached pulp (with low k-value) appeared to be beneficial for subsequent TCF-bleaching with hydrogen peroxide.

  • 43.
    Gellerstedt, Göran
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, MonicaKTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.Henriksson, GunnarKTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Wood Chemistry and Wood Biotechnology2009Collection (editor) (Refereed)
    Abstract [en]

    The production of forestry products is based on a complex chain of knowledge in which the biological material wood with all its natural variability is converted into a variety of fiber-based products, each one with its detailed and specific quality requirements. This four volume set covers the entire spectrum of pulp and paper chemistry and technology from starting material to processes and products including market demands. Supported by a grant from the Ljungberg Foundation, the Editors at the Royal Institute of Technology, Stockholm, Sweden coordinated over 30 authors from university and industry to create this comprehensive overview. This work is essential for all students of wood science and a useful reference for those working in the pulp and paper industry or on the chemistry of renewable resources.

  • 44.
    Gellerstedt, Göran
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lignins: Major sources structure and properties2008In: Monomers, polymers and composites from renewable resources / [ed] M.N. Belgacem and A. Gandi, Elsevier, 2008, p. 201-224Chapter in book (Other academic)
    Abstract [en]

    Lignin is one of the most predominant biopolymers present in plants. Together with cellulose and hemicelluloses, lignin builds up the cell wall in an arrangement which is regulated on the nano-scale and results in lignin-carbohydrate network structures. The molecular complexity of lignin renders all isolation and identification processes difficult and, consequently, many structural questions still remain. This chapter reviews the present knowledge about the formation of lignin in plants, its presence in different types of plants as well as several different approaches taken to reveal the chemical structure, is summarized. Furthermore, this chapter briefly discusses the chemical changes introduced in lignin as the result of different types of delignification processes, such as kraft and sulfite pulping and steam explosion, is included.

  • 45.
    Gellerstedt, Göran L. F.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Biorefinery lignins - A feedstock for chemicals and materials2008In: 2008 Nordic Wood Biorefinery Conference, NWBC 2008 - Proceedings, 2008, p. 111-113Conference paper (Refereed)
    Abstract [en]

    The rapid expansion of bioethanol production will, in addition to fermentation of sugar and starch sources, also involve a conversion of lignocellulosic materials. In addition to carbohydrates, this will result in large amounts of lignin which can be used as process fuel but also serve as a feedstock for chemicals. Modern kraft mills constitute a second source of lignin since the energy balance is such that a partial outtake of lignin can be permitted. Irrespective of source, technical lignins must be upgraded, e.g. by purification in order to acquire properties which make them suitable as feedstock in value-added products.

  • 46.
    Gellerstedt, Göran
    et al.
    KTH, Superseded Departments, Pulp and Paper Technology.
    Li, Jiebing
    KTH, Superseded Departments, Pulp and Paper Technology.
    An HPLC method for the quantitative determination of hexeneuronic acid groups in chemical pulps1996In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 294, p. 41-51Article in journal (Refereed)
    Abstract [en]

    It has recently been demonstrated that 4-deoxy-L-threo-hex-4-enopyranosyluronic acid (''hexeneuronic acid'') is present in kraft pulps and linked to the xylan backbone. An analytical method for the quantitative determination of hexeneuronic acid groups has now been developed. The procedure involves a selective hydrolysis with mercuric acetate of the glucosidic linkage between the hexeneuronic acid group and the xylan chain, followed by oxidation with periodate to form P-formyl pyruvic acid. The latter is reacted with thiobarbituric acid, and the red-coloured adduct formed is separated by reverse phase HPLC and quantified by measuring the absorbance at 549 nm, Some kraft pulps have been analysed to illustrate the contribution of hexeneuronic acid groups to the total amount of oxidizable structures present in such pulps.

  • 47.
    Gellerstedt, Göran
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Improved lignin properties and reactivity by modifications in the autohydrolysis process of aspen wood2005Conference paper (Refereed)
  • 48.
    Gellerstedt, Göran
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lignin for material applications2009Conference paper (Refereed)
  • 49.
    Gellerstedt, Göran
    et al.
    KTH, Superseded Departments, Pulp and Paper Technology.
    Li, Jiebing
    KTH, Superseded Departments, Pulp and Paper Technology.
    Xylan degradation products from birch kraft pulp1995In: Proceedings of the 8th International Symposium on Wood and Pulping Chemistry, Helsinki: Vol. I, 1995, p. 533-540Conference paper (Other academic)
  • 50.
    Gellerstedt, Göran
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Eide, Ingvar
    Kleinert, Mike
    Barth, Tanja
    Chemical Structures Present in Biofuel Obtained from Lignin2008In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 22, no 6, p. 4240-4244Article in journal (Refereed)
    Abstract [en]

    Technical lignins from various sources can be converted into bio-oil with a low O/C ratio by pyrolysis in the presence of formic acid and an alcohol. By application of different analytical techniques, such as Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), electrospray ionization mass spectrometry (ESI-MS), and size-exclusion chromatography (SEC), it has been shown that a complete degradation of the lignin takes place irrespective of the origin. The resulting bio-oil has a low-molecular-mass distribution with a preponderance of aliphatic hydrocarbon structures. A substantial number of phenolic compounds are, however, also present, and some of these also contain carboxyl groups. The results clearly show that formic acid is a powerful supplier of atomic hydrogen. By further optimization of the pyrolysis reaction, it should be possible to further reduce the content of aromatic structures.

123 1 - 50 of 126
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