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  • 1.
    Enberg, Sofia
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Norske Skog Saugbrugs, NO-1756 Halden, Norway.
    Opdal, Øivind
    Norske Skog Saugbrugs, NO-1756 Halden, Norway.
    Axelsson, Patrik
    Norske Skog Saugbrugs, NO-1756 Halden, Norway.
    Eriksen, Øyvind
    Paper & Fibre Res Inst, NO-7491 Trondheim, Norway.
    Rundlöf, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Capisco Sci & Art, SE-60234 Norrkoping, Sweden.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. AkzoNobel Pulp & Performance Chem, SE-44580 Bohus, Sweden.
    Mapping and modelling of optical properties from pulp to super calendered paper2015In: Appita journal, ISSN 1038-6807, Vol. 68, no 2, p. 128-138-Article, review/survey (Refereed)
    Abstract [en]

    During production of mechanical pulp based paper, the pulp darkenswithin the process which represents a significant cost for the mill. Amapping of the optical properties of the pulp was conducted along theprocess, from pulp mill to paper machine, at a mill producing supercalendered (SC) paper on three paper machines. The focus was to evaluateat which positions in the mill the discolouration occurs and also whichfraction of the pulp darkens the most.The fine fraction of the pulp darkened more than the long fibrefraction. Bleached pulp diluted with white water from the paper machinedarkened more during storage than pulp diluted with clear filtrate. Thewhite water contains a considerable amount of suspended solids, i.e.pulp fines and clay. There was a tendency for a shoulder in absorptionspectra of the pulp stored in white water from the paper machine in theregion 550 to 650 nm, both for fibres and for fines. This is in the sameregion where the added dyes have their absorption maxima and also somecomplexes between iron and some of the components among lignin and theextractives. Simulation of retention times of different fractions showedthat, although the main part of the fine material is retained in thepaper within a few hours, a small part might circulate for considerablylonger time.

  • 2.
    Enberg, Sofia
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Norske Skog Saugbrugs, NO-1756 Halden, Norway.
    Rundlöf, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. AkzoNobel Pulp & Performance Chem, SE-85170 Bohus, Sweden.
    Axelsson, Patrik
    Norske Skog Saugbrugs, NO-1756 Halden, Norway.
    Eriksen, Oyvind
    Paper & Fibre Res Inst, NO-7491 Trondheim, Norway.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Some causes of formation of colour during storage of hydrogen-peroxide bleached Norway spruce mechanical pulp2014In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 29, no 2, p. 356-366Article in journal (Refereed)
    Abstract [en]

    The discolouration of hydrogen-peroxide bleached Norway spruce mechanical pulp during storage in mill systems was studied and the contributions of process water, iron and dyes were evaluated over the visible spectrum. Washing of the pulp made it less sensitive to storage, possibly due to the removal of extractives, lignin-like substances, iron and pulp fines. Storage in white water gave extensive discolouration with a shoulder in the absorption spectrum at around 550-650 nm. Most of the colour was associated with pulp fines or filler but some colour was also found in smaller fractions and in the water phase. The addition of ferric ions increased the light absorption coefficient during storage, initially at short wavelengths and then over the whole spectrum, but could not explain the increased absorption at 550-650 nm and could not be the only cause of the darkening in the mill system. A cationic basic violet dye gave a shoulder in the absorption spectrum similar to that in the mill system, but the absorption in this area did not increase during storage. Model calculations indicate that ferric ions together with violet and red dyes could explain a major part, but not all, of the colour observed in the mill system after storage. The darkening not accounted for at longer wavelengths and around 550-650 nm is suggested to be related to fines and fillers including dissolved and colloidal substances associated with these particles.

  • 3.
    Enberg, Sofia
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Rundlöf, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Axelsson, Patrik
    Norske Skog Saugbrugs, NO-1756 Halden, Norway.
    Eriksen, Oyvind
    Paper & Fibre Res Inst, NO-7491 Trondheim, Norway.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    The influence of process waters on optical properties during storage of hydrogen-peroxide bleached Norway spruce mechanical pulp2014In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 29, no 2, p. 344-355Article in journal (Refereed)
    Abstract [en]

    To evaluate the causes behind the formation of colour in mill systems, the effect of different process waters on the optical properties of hydrogen-peroxide bleached Norway spruce mechanical pulp during storage was studied. The influence of process water type, temperature, time, pulp consistency and pH was evaluated over the visible range of wavelengths. The darkening was more pronounced when pulp was stored in process waters compared to in distilled water. Increased temperature and prolonged storage times increased the darkening as expected, whereas a higher storage consistency gave less darkening than a lower storage consistency (15% compared to 5%). The pH value that gave the lowest brightness reduction and a minimum in Delta k(460) was found to be 5.5-6.0. Storage of pulp in white water from the paper machine resulted in a broad shoulder in the k spectra indicating colour formation related to the particles in this water. Part of this shoulder in absorption spectra was related to added dyes, but the increase in absorption with time is likely to be caused by some other colour formation. The colour measured as a*, b* showed that the storage changed the colour of the pulp towards red and yellow, and initially more towards red.

  • 4.
    Enberg, Sofia
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Norske Skog Saugbrugs AS, NO-1756 Halden, Norway .
    Rundlöf, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Capisco Science and Art, SE-602 34 Norrköping, Sweden.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. AkzoNobel Pulp and Performance Chemicals, SE-445 80 Bohus, Sweden.
    Johnsen, Ingvild A.
    Paper and Fibre Institute, NO-7491 Trondheim, Norway .
    Axelsson, Patrik
    Norske Skog Saugbrugs AS, NO-1756 Halden, Norway .
    The influence of process conditions during pulp storage on the optical properties of Norway spruce mechanical pulps2013In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 28, no 2, p. 203-210Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to study the influence of process conditions (time, pH, temperature and consistency) on the optical properties of mechanical pulps during storage in a clean system as a reference for further work. Laboratory storage trials were performed with unbleached and hydrogen-peroxide bleached well-washed Norway spruce pulps. In general, the pulp darkened during storage due to an increase in light absorption, especially at shorter wavelengths. After long storage times, the light absorption coefficient, k had increased also at longer wavelengths. No specific peaks were seen in Delta k-spectra. The increase in light absorption was most rapid initially, during the first four hours, for all pulps when stored at high temperature (80 degrees C), and then proceeded more slowly. The corresponding change in colour, measured as a* and b*, was shifted towards red and somewhat towards yellow, and over longer periods of storage, the shift towards yellow became greater. Time and temperature were found to have the largest impact. The effects were similar regardless of the starting pH (4.3-9.7) and pulp consistency (5%-25%). The hydrogen-peroxide bleached pulps were more sensitive to storage compared to the unbleached pulp at temperatures above 50 degrees C. At storage times of up to four hours, the unbleached pulp showed no loss of brightness at either of the storage temperatures. A slightly less bleached pulp darkened more than a highly bleached pulp at all wavelengths. The only difference measured between the two pulps was that the less bleached pulp had a higher content of iron. This higher iron content may be at least part of the reason for the more extensive darkening.

  • 5.
    Engstrand, Per
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ferritsius, Rita
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Rundlöf, Mats
    Capisco AB.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Decrease in strengthalong a process line for SC paper2019In: Fundamental Mechanical Pulp Research Seminar, FMPRS2019, Norrköping, SwedenArranged by Mid Sweden University in cooperatrion with Holmen AB, Valmet AB, AF AB and Treesearch., 2019Conference paper (Refereed)
  • 6.
    Fjellström, Helena
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Höglund, Hans
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Forsberg, Sven
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    The UV-screening properties of coating layers: The influence of pigments, binders and additives2009In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, no 2, p. 206-212Article in journal (Refereed)
    Abstract [en]

    The ability of coating colours to obstruct ultraviolet (UV) radiation in the 300-385 nm region was examined with the aim of finding the best photo-stabilising formulation to inhibit discoloration of high-yield pulps. The influence of pigment type, bleaching of the pigments, pigment size, pigment size distribution, type of binder and addition of U-V-absorbing compounds were examined using a newly developed method for studying the reflectance and transmittance properties of thin coating layers.

    The pigment type and coat weight was found to be the most important factors for reducing the transmittance of UV-radiation. Kaolin clays were more effective than calcium carbonate pigments and are therefore a better coating pigment for photostability reasons. Bleaching of the pigments, resulted in an overall minor decrease in transmittance for both kaolin and ground calcium carbonate (GCC) pigments, especially at low coat weights. Bleaching of the pigments changed the particle size distribution somewhat, which probably alters the structure in the coating layer. Precipitated calcium carbonate (PCC) pigments have a higher UV-screening potential compared to GCC pigments and should therefore be a better choice among the calcium carbonates. It was further concluded that a narrow pigment size distribution was beneficial for reducing the amount of transmitted UV-radiation that reaches the base paper. Styrene butadiene latex and polyvinylpyrrolidone were better in reducing the transmittance in the UV-region than polyvinyl alcohol.

    Adding a fluorescent whitening agent to a coating colour decreased the transmittance in the UV-region when the pigment was of the GCC type, and increased the transmittance when kaolin pigment was used. Addition of titanium dioxide (3 parts) to a coating colour containing kaolin pigment blocked about 90% of the UV-radiation at a coat weight of 10 g/m(2), which is a common coat weight for a single coated paper. Another possibility is to double coat to increase the coat weight, which turns the transmittance factor closed to zero.

  • 7.
    Hellström, P.
    et al.
    AkzoNobel Pulp and Performance Chemicals, 445 80 Bohus, Sweden.
    Heijnesson-Hultén, A.
    AkzoNobel Pulp and Performance Chemicals, 445 80 Bohus, Sweden.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. AkzoNobel Pulp and Performance Chemicals, 445 80 Bohus, Sweden.
    Håkansson, H.
    Department of Engineering and Chemical Sciences, Karlstad University, 651 88 Karlstad, Sweden .
    Germgård, U.
    Department of Engineering and Chemical Sciences, Karlstad University, 651 88 Karlstad, Sweden .
    The effect of Fenton chemistry on the properties of microfibrillated cellulose2014In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, no 3, p. 1489-1503Article in journal (Refereed)
    Abstract [en]

    A fully bleached birch kraft pulp was treated with acidic hydrogen peroxide in the presence of ferrous ions (Fenton's reagent) and thereafter treated mechanically in a colloid mill to produce a product containing microfibrillated cellulose (MFC). The produced MFC products were chemically and morphologically characterized and compared with MFC products produced without pretreatment as well as with enzymatic hydrolysis. Fenton treatment resulted in an increase in total charge and number of carbonyl groups while the intrinsic viscosity decreased. The Fenton treated pulps were easier to process mechanically i.e. they reached a higher specific surface area at a given mechanical treatment time and the MFC produced had a stable water-fibre suspension for at least 8 weeks compared to enzymatic pretreated pulps and pulps not subjected to any pretreatment. © 2014 Springer Science+Business Media Dordrecht.

  • 8.
    Hellström, Pia
    et al.
    Akzo Nobel Pulp & Paper Performance Chem AB, Bleaching Chem Applicat RD&I, Bohus, Sweden.;Karlstad Univ, Karlstad, Sweden.
    Heijnesson-Hulten, Anette
    Akzo Nobel Pulp & Paper Performance Chem AB, Bleaching Chem Applicat RD&I, Bohus, Sweden.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Akzo Nobel Pulp & Performance Chem AB, Bleaching Chem Applicat RD&I, Bohus, Sweden.
    Hakansson, Helena
    Karlstad Univ, Chem Engn, Karlstad, Sweden.
    Germgard, Ulf
    Karlstad Univ, Pulp Technol, Karlstad, Sweden.
    A comparative study of enzymatic and Fenton pretreatment applied to a birch kraft pulp used for MFC production in a pilot scale high-pressure homogenizer2016In: TAPPI Journal, ISSN 0734-1415, Vol. 15, no 6, p. 375-381Article in journal (Refereed)
    Abstract [en]

    Microfibrillated cellulose (MFC) was produced in pilot scale from a bleached birch (Betula verrucosa) kraft pulp that was pretreated with either Fenton's reagent or with a combined mechanical and enzymatic method used at the Centre Technique du Papier (CTP; Grenoble, France). The change in fiber fibrillation during the homogenization treatment was monitored by analyzing the fiber and the fines content, size fractionation, rheological properties and visualization by light-and scanning electron microscopy (SEM). The Fenton pretreatment resulted in MFC suspensions that contained a high amount of small sized elements. After five passes through the high-pressure homogenizer, the amount of particles smaller than 20 mu m was 37% for the Fenton pretreated MFC compared to 13% for the enzymatically (endoglucanase) pretreated MFC. Altogether, the Fenton pretreatment enabled preparation of MFC with a higher degree of fibrillation after the same number of passes through the high-pressure homogenizer. Another option is to produce MFC of the same amount of fibrillation as after an enzymatic stage, but at significantly lower energy consumption.

  • 9.
    Hellström, Pia
    et al.
    AkzoNobel Pulp & Performance Chem, SE-44580 Bohus, Sweden.
    Heijnesson-Hultén, Anette
    AkzoNobel Pulp & Performance Chem, SE-44580 Bohus, Sweden.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. AkzoNobel Pulp & Performance Chem, SE-44580 Bohus, Sweden.
    Håkansson, Helena
    Karlstad Univ, Dept Engn & Chem Sci, SE-65188 Karlstad, Sweden.
    Germgård, Ulf
    Karlstad Univ, Dept Engn & Chem Sci, SE-65188 Karlstad, Sweden.
    Fenton pre-treated microfibrillated cellulose evaluated as a strength enhancer in the middle ply of paperboard2014In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 29, no 4, p. 732-740Article in journal (Refereed)
    Abstract [en]

    Microfibrillated celluloses (MFCs), produced by various pre-treatments of a fully bleached birch kraft pulp, were evaluated as strength enhancers in test sheets representing the middle ply of paperboard. The furnish consisted of hydrogen peroxide bleached high temperature spruce chemithermomechanical pulp (HT-CTMP), MFC and a retention system containing cationic starch and an anionic silica sol. The MFC was prepared via a mechanical treatment in a colloid mill after pretreatment with Fenton's reagent, monocomponent endoglucanase or acidic hydrogen peroxide. Addition of 5% MFC, produced with Fenton pre-treatment, resulted in improved HT-CTMP properties with respect to increased tensile index (similar to 35%), z-directional strength (similar to 50%), tensile stiffness index (similar to 25%) compared to HT-CTMP test sheets prepared without MFC addition. The strength improvement was linearly correlated to the density of the tests sheet, to the surface area (BET) and to the surface charge of the enzymatic or chemically pre-treated MFCs.

  • 10.
    Karlsson, Anette
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Enberg, Sofia
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Rundlöf, Mats
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Edström, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Determining optical properties of mechanical pulps: Sheetmaking procedure and investigation of different ways to evaluate light absorption2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 3, p. 531-541Article in journal (Refereed)
    Abstract [en]

    A method to produce representative sheets for determination of optical properties of mechanical pulps has been developed. It reduces the risk of contamination and discoloration and can be used with small pulp quantities. The deviation from the expected linear behaviour of the light scattering coefficient, s, at wavelengths corresponding to strong light absorption, has been studied using the Kubelka-Munk model and the angular resolved DORT2002 radiative transfer solution method. This decrease in s could not be explained by errors introduced in the Kubelka-Munk modelling by anisotropic scattering. Linear extrapolation of s can therefore not be justified as a way to obtain a more correct light absorption coefficient, k. For thepulps studied, the decrease in s at short wavelengths had little effect on k at 457 nm.

  • 11.
    Karlsson, Anette
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Reduced heat-induced darkening and enhanced bleachability of mechanical pulps studied using the UV-visible absorption spectraManuscript (preprint) (Other academic)
  • 12.
    Karlsson, Anette
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. SCA R and D Centre AB, SE-851 21 Sundsvall, Sweden.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. AkzoNobel Pulp and Performance Chemicals, SE-445 80 Bohus, Sweden.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Strategies to reduce heat-induced darkening for enhanced bleachability of mechanical pulps2014In: Appita journal, ISSN 1038-6807, Vol. 67, no 1, p. 50-57Article in journal (Refereed)
    Abstract [en]

    Under mechanical pulping conditions, elevated temperature initiates reactions in the wood constituents resulting in the formation of coloured structures. In an attempt to reduce the formation of colour, a number of additives have been examined to assess their ability to inhibit heat-induced darkening of a Norway spruce (Picea abies) stone groundwood (SGW) pulp. SGW pulp was used as a model pulp with the purpose of imitating a thermomechanical pulp (IMP). The heat-treated SGW pulp, both with and without additives present, was subsequently bleached with 4.5% hydrogen peroxide at high pulp consistency and with varying alkali charges in order to examine the hydrogen peroxide bleachability of such pulps. Heat treatment at 170 °C resulted in a loss of brightness of about 4% ISO after heating for 60 seconds. The reduction in brightness could only partly be regained through high consistency hydrogen peroxide bleaching; the SGW pulp displayed a brightness of 83.7% ISO whereas the heat-treated SGW pulp reached a brightness of 80.4% ISO. Heat treatment with a low addition rate (1 %) of alkaline hydrogen peroxide, sodium bisulfite or sodium sulfite, with a subsequent hydrogen peroxide bleaching stage, resulted in an improved bleached brightness of about 81.6% ISO, i.e. the loss of brightness due to heat was still approximately 2% ISO. Sodium borohydride (1 %) did not suppress the thermal darkening but improved the bleached brightness by approximately 2% ISO compared to the heat-treated SGW pulp and resulted in a brightness of 82.6% ISO. Addition of a chelating agent (DTPA, 0.11 and 0.45%) and the radical scavengers phthalic hydrazide (1 %) and 1 -hexanol (1 %) suppressed the heat-induced darkening somewhat but did not improve the hydrogen peroxide bleachability to any noticeable extent. Addition of citric acid (0.6%) did not suppress the thermal darkening and resulted in impaired bleachability.

  • 13. Li, Shiming
    et al.
    Lundquist, Knut
    Paulsson, Magnus
    Skogsindustriell kemiteknik, CTH.
    Synthesis of guaiacylglycerol β-guaiacyl ether1995In: Acta Chemica Scandinavica, ISSN 0904-213X, E-ISSN 1902-3103, Vol. 49, no 8, p. 623-624Article in journal (Refereed)
  • 14.
    Logenius, Louise
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Karlström, A.
    Chalmers Industriteknik, SE-41288 Gothenburg, Sweden.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Improved hydrogen peroxide bleaching of mechanical pulps using carbon dioxide in combination with sodium and magnesium based alkali sources2011In: 16th International Symposium on Wood, Fiber and Pulping Chemistry - Proceedings, ISWFPC, 2011, Vol. 1, p. 741-745Conference paper (Refereed)
    Abstract [en]

    The pH-profile in the hydrogen peroxide bleaching stage of a Norway spruce thermomechanical pulp was levelled out by using carbon dioxide in combination with sodium or magnesium based alkali sources. Addition of carbon dioxide when magnesium hydroxide was used as the alkali source increased the pulp brightness with up to 1.5 brightness units when the bleaching was performed at 70 °C. When the temperature was increased from 70°C to 90 °C the brightness was increased with about two brightness units, addition of carbon dioxide increased it further. The residual hydrogen peroxide and the chemical oxygen demand (COD) levels were not affected as a consequence of the carbon dioxide addition. In the experiments where sodium hydroxide was used as the alkali source, addition of carbon dioxide lowered the pH that resulted in a decreased COD level, a slightly lower brightness level and, to some extent, an increased residual hydrogen peroxide level.

  • 15.
    Nelsson, E.
    et al.
    Holmen AB, New Business Development.
    Sandberg, C.
    Holmen Paper AB, Paper Product Developmen.
    Svensson-Rundlöf, E.
    Holmen Paper AB, Paper Product Developmen.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Akzo Nobel Pulp and Perfomtance Chemicals AB.
    Granfeldt, Thomas
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Valmet AB.
    Engberg, Birgitta
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Mill scale production of TMP with double disk refining-The effects of a mild sulfonation, atmospheric preheating and refining temperatures2016In: International Mechanical Pulping Conference 2016, IMPC 2016, TAPPI Press, 2016, p. 249-259Conference paper (Refereed)
    Abstract [en]

    The aim of this work was to study the effects of a mild dosage of sodium sulfite in chip impregnation at diffen temperatures during atmospheric preheating and during refining for production of TMP for printing papers usi high intensity double disk refining. Two trials were performed in the 800 bdt/day double disc line at I Braviken paper mill (Holmen Paper AB, Sweden) using Norway spruce chips. During the trials, chips w( impregnated in an Impressafiner where chips were preheated at 1.8 bar(g) for a few seconds and th compressed before impregnation. During impregnation, sodium sulfite was added to chips at pH 9 in dosages 0.6 or 1.2%. Reference pulps without addition of sulfite were also produced. In the first trial, the effect different temperatures and retention times (80°C for 6 minutes vs. 96°C for 9 minutes) in the atmosphe preheating bin following impregnation was evaluated both with and without the addition of 1.2% sodium sulf In the second trial, the effect of different refining temperatures (refiner house pressures of 4.6 or 6.4 bar(g), 1 or 167°C) was evaluated with different additions of sodium sulfite (0.0, 0.6 or 1,2%) during impregnation. The results from the two trials showed that the increase in refiner house pressure increased the tensile index pulps both with and without addition of sodium sulfite, when compared at certain SEC. However, the increase preheater bin temperature and retention time did not increase the tensile index of pulps but rather led to a sm reduction in tensile index when combined with an addition of 1.2% sodium sulfite. The two different methc used to increase the temperature in the system led to different effects in the disc gap at certain SEC. The disc j temperature was increased by both methods but disc gap was only reduced at certain SEC when the refini temperature was increased by increasing the refiner housing pressure. The difference in the effect on the disc j may hold the answer to the different effects seen in tensile index.

  • 16.
    Paulsson, Magnus
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Parkås, Jim
    Sodra Innovat, Sodra Cell Varo, SE-43024 Varobacka, Sweden.
    Review: Light-Induced Yellowing Of Lignocellulosic Pulps - Mechanisms And Preventive Methods2012In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, no 4, p. 5995-6040Article, review/survey (Refereed)
    Abstract [en]

    This review will focus on recent progress regarding the mechanisms of light-induced discoloration of mechanical and chemimechanical pulps and on the proposed preventive treatments. It is evident that the mechanisms behind photoyellowing of lignin-rich pulps are complex and that several types of reaction pathways may coexist. Photoyellowing proceeds via one initial fast phase and a slower following phase. The fast phase has been ascribed to oxidation of free phenolic groups and/or hydroquinones and catechols to photoproducts of mainly quinonoid character. A multitude of reactions involving several lignin subunits are possible. Important intermediates are phenoxyl radicals, and to some extent ketyl radicals. The importance of the phenacyl aryl ether pathway might be more important than previously thought, even though the original content of such groups is low in lignin. Even though many preventive methods against photoyellowing have been suggested, no cost-efficient treatment is available to hinder photoreversion of lignin-containing paper permanently. Suggested methods for stabilization include chemical modification (etherification and esterification), coating the paper product, addition of radical scavengers, excited state quenchers, or ultraviolet absorbing compounds.

  • 17.
    Paulsson, Magnus
    et al.
    Skogsindustriell kemiteknik, CTH.
    Simonson, Rune
    Westermark, Ulla
    Chemical modification of lignin-rich paper: Part 1. Acetylation of paper made from spruce TMP and aspen CTMP. Evaluation of paper properties.1994In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 9, no 4, p. 232-236Article in journal (Refereed)
  • 18.
    Paulsson, Magnus
    et al.
    Skogsindustriell kemiteknik, CTH.
    Simonson, Rune
    Westermark, Ulla
    Chemical modification of lignin-rich paper: Part 2. Photostabilization by acetylation of paper made from spruce TMP and aspen CTMP1995In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 10, no 1, p. 62-67Article in journal (Refereed)
  • 19.
    Ragauskas, Arthur J.
    et al.
    Georgia Inst Technol, Sch Chem, Inst Paper Sci & Technol, Atlanta, GA 30332 USA.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Akzo Nobel Pulp & Performance Chem AB, Bohus, Sweden.
    Goyal, Gopal
    Corp Technol Ctr, Loveland, OH, USA.
    Editorial perspective on bleaching: Today and tomorrow2013In: TAPPI Journal, ISSN 0734-1415, Vol. 12, no 10, p. 5-6Article in journal (Other academic)
  • 20.
    Salmen, L.
    et al.
    Innventia AB, Stockholm, Sweden .
    Viforr, S.
    Innventia AB, Stockholm, Sweden .
    Mårtensson, T.
    Innventia AB, Stockholm, Sweden .
    Sixta, H.
    Aalto Univ. Espoo, Finland.
    Ylönen, T.
    Aalto Univ. Espoo, Finland.
    Fernando, D.
    SLU, Uppsala, Sweden.
    Daniel, G.
    SLU, Uppsala, Sweden.
    Sandström, P.
    SCA, R and D CENTRE, Sundsvall, Sweden.
    Moberg, A.
    StoraEnso, Karlstad, Sweden .
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. AkzoNobel Pulp and Performance Chemicals, Bohus, Sweden .
    Back, R.
    SCA, R and D CENTRE, Sundsvall, Sweden.
    Enzymatic chip treatment for TMP - Prospects2014In: International Mechanical Pulping Conference, IMPC 2014, 2014Conference paper (Refereed)
    Abstract [en]

    In order to evaluate enzyme pre-treatments of chips as means of lowering the energy demand in mechanical pulping, impregnation and refining trials were performed. Wing refining showed that property development was similar to that of reference pulps in the case of pectinase and xylanase while for chips treated with mannanase a less favourable development of the tensile index was noted. Considering the highly increased possibility for enzymatic interactions reached with greater disintegration of chips it could well be that the possibilities for enzymes to attack desired fibre wall structures may have been too few even in the case of Impressafiner treated material used here.

  • 21.
    Walter, K.
    et al.
    AkzoNobel Pulp and Performance Chemicals, Bohus, Sweden.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. AkzoNobel Pulp and Performance Chemicals, Bohus, Sweden.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Acid hydrogen peroxide treatment of Norway spruce TMP: The effect of chelated ferric ions2014In: International Mechanical Pulping Conference, IMPC 2014, Paper Engineer's Association (PI) , 2014Conference paper (Refereed)
    Abstract [en]

    The effect of treating thermomechanical pulp with Fenton chemistry was evaluated in a model study. Ferrous ions and chelated ferric ions were compared as catalysts while initial pH was varied. The results showed that a catalyst of ferrous sulphate had a greater impact on the pulp (increased total fibre charge and carbonyl groups, more dissolved organic material in filtrate) than ferric ions chelated with EDTA. If using ferric-EDG as catalyst, the hydrogen peroxide consumption was higher and more hydroxyl radicals were detected compared to if using ferrous sulphate. Ferric-EDG, however, gave similar or less effect on the pulp.

  • 22.
    Walter, Karin
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. AkzoNobel Pulp & Performance Chem, SE-44580 Bohus, Sweden.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. AkzoNobel Pulp & Performance Chem, SE-44580 Bohus, Sweden.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Acid Hydrogen Peroxide Treatment of Norway Spruce TMP: The Effect of an Extended pH Range when Catalyzed by Free Ferrous and Free or EDG/EDTA-Chelated Ferric Ions2014In: Journal of wood chemistry and technology, ISSN 0277-3813, E-ISSN 1532-2319, Vol. 34, no 2, p. 135-155Article in journal (Refereed)
    Abstract [en]

    The influence of different types of iron salts (i.e., ferrous or ferric cations with sulphate, nitrate or chloride anions) on the reaction between coarse thermomechanical pulp and acid hydrogen peroxide (Fenton chemistry) was studied when the initial pH was 3.2 and 5.3. Also, ferric ions chelated with EDTA or EDG at different molar ratios were compared with ferrous sulphate when the initial pH was extended from about 3 to 8. Different anions of ferric ion salt gave a similar catalytic effect. At an initial pH of 7–8, the ferric-EDTA catalyzed reaction resulted in similar or higher hydrogen peroxide consumption and more detectable hydroxyl radicals than the ferrous sulphate catalyzed reaction, but less reaction with the pulp was indicated. Between pH 5–8, using Fe-EDG as a catalyst gave higher hydrogen peroxide consumption and more detectable hydroxyl radicals than if using ferrous sulphate; however, the measured effect on the pulp was similar or less.

  • 23.
    Walter, Karin
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics. AkzoNobel Pulp and Performance Chemicals , Bohus , Sweden.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics. AkzoNobel Pulp and Performance Chemicals , Bohus , Sweden.
    Hellström, Pia
    AkzoNobel Pulp and Performance Chemicals , Bohus , Sweden.
    Acid hydrogen peroxide treatment of Norway Spruce TMP: A model study using free ferrous ions and ferric ions chelated with EDTA as catalysts2013In: Journal of wood chemistry and technology, ISSN 0277-3813, E-ISSN 1532-2319, Vol. 33, no 4, p. 267-285Article in journal (Refereed)
    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.

  • 24.
    Walter, Karin
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Hellström, Pia
    Nilsson, Pär
    Energy efficient production of TMP by using acid hydrogen peroxide: Factors affecting the hydrogen peroxide consumption2011In: Proceedings of International Mechanical Pulping Conference 2011, 2011, p. 484-487Conference paper (Refereed)
  • 25.
    Walter, Karin
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Wackerberg, Eva
    Energy efficient refining of Black spruce TMP by using acid hydrogen peroxide: Part 1. A pilot plant study2009In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, no 3, p. 255-265Article in journal (Refereed)
    Abstract [en]

    The potential of using acid hydrogen peroxide for lowering the

    electrical energy consumption during production of Black spruce (Picea

    mariana) thermomechanical pulp (TMP) was investigated. The chemical

    system, which consisted of ferrous sulphate, hydrogen peroxide and

    optionally an enhancer [ethylenediaminetetraacetic acid (sodium salt),

    3,4-dimethoxybenzyl (veratryl) alcohol or oxalic acid/sodium oxalate],

    was evaluated as an inter-stage treatment where the primary refiner was

    used as a mixer. The approach has the advantage of minimising the

    capital investment needed for implementation, thus being directly

    applicable in a thermomechanical pulping process consisting of two or

    more refiners in series.

    The results obtained in a pilot plant trial revealed that is was

    possible to significantly reduce the specific energy consumption by

    approximately 20-and 35% to a freeness value of 100 ml CSF by using 1

    and 2% hydrogen peroxide, respectively. The energy reduction could be

    obtained without any substantial change in fibre length, fractional

    composition of the pulp or tensile strength of the paper. The tear

    strength was slightly reduced however, as was the pulp yield. The major

    drawback with the acid hydrogen peroxide system was a reduction in

    brightness by at least 6 brightness units. The addition level of

    ferrous sulphate was too high and the possibility to reducing the

    discoloration should be considerable when the chemical system is

    optimized.

     

  • 26.
    Walter, Karin
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Wackerberg, Eva
    Eka Chemicals AB, Bohus, Sweden.
    Energy efficient refining of Black spruce TMP by using acid hydrogen peroxide: Part 2. Washing, chelating and bleaching studies2009In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, no 3, p. 266-272Article in journal (Refereed)
    Abstract [en]

    The acid hydrogen peroxide system has the potential to significantly

    reduce the specific energy consumption in the production of softwood

    thermomechanical pulps (TMPs). A drawback of the chemical system is

    discoloration of the pulp during refining. The work presented in this

    study evaluates the possibility to regain the lost brightness by

    washing, chelating and sodium dithionite or hydrogen peroxide bleaching

    of the treated pulps.

    A washing or chelating procedure can reduce the metal ion content of

    the chemically treated TMPs considerably, though brightness can be

    increased by a maximum of two ISO units. The amount of iron can be

    further reduced to a level similar to that of untreated pulps by

    performing a reducing agent-assisted chelating stage (Q(Y)) with

    dithionite. The discoloration cannot,, however, be completely

    eliminated. The brightness decrease-of the treated pulps is thus not

    only caused by higher iron content in the pulp, but is also dependent

    on the type of iron compound and/or other coloured compounds connected

    with the acid hydrogen peroxide treatment.

    Oxidative bleaching with hydrogen peroxide (P) is more effective than

    reductive bleaching with sodium dithionite in regaining the brightness

    lost during the energy reductive treatment. By using a Q(Y) P sequence,

    a hydrogen peroxide charge of 3.8% was needed to reach an ISO

    brightness of 75% for the chemically treated pulps. The corresponding

    hydrogen peroxide charge for the untreated TMP reference was 2.5%.

     

  • 27.
    Walter, Karin
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Wackerberg, Eva
    Energy efficient refining of Black spruce TMP by using acid hydrogen peroxide: Part 3. Chemical and morphological characterisation2010In: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 36, no 1-2, p. 2-9Article in journal (Refereed)
  • 28.
    Walter, Karin
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Paulsson, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Wackerberg, Eva
    Energy-efficient refining of Black spruce TMP using acid hydrogen peroxide2009In: Proceedings - 2009 International Mechanical Pulping Conference, IMPC 2009, Stockholm: SPCI , 2009, p. 286-291Conference paper (Refereed)
    Abstract [en]

    By using Fenton chemistry (hydrogen peroxide, ferrous iron, pH<4) as an inter-stage treatment during production of Black spruce thermomechanical pulp, the specific energy consumption can be reduced by at least 20% to a constant tensile strength. The energy reduction can be achieved with preserved fibre length and cross-sectional dimensions. However, the fibre cross-sectional shape is affected, and fibres of the chemically treated pulps had the highest collapse index. A drawback with the acid hydrogen peroxide system is a decrease in pulp yield and a reduction in brightness. Different approaches for lowering the iron content of the chemically treated pulps prior to bleaching are presented. The discoloration is advantageously reduced (but not completely eliminated) by hydrogen peroxide bleaching.

     

     

1 - 28 of 28
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