Change search
Refine search result
1 - 9 of 9
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Dang, Binh T. T.
    et al.
    Chalmers Univ Technol, Dept Chem & Biol Engn, Forest Prod & Chem Engn, SE-41296 Gothenburg, Sweden..
    Brelid, Harald
    Sodra Innovat, SE-43286 Varobacka, Sweden..
    Theliander, Hans
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Chalmers Univ Technol, Dept Chem & Chem Engn, Forest Prod & Chem Engn, SE-41296 Gothenburg, Sweden.
    Carbohydrate content of black liquor and precipitated lignin at different ionic strengths in flow-through kraft cooking2018In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, no 7, p. 539-547Article in journal (Refereed)
    Abstract [en]

    The influence of sodium ion concentration [Na+] on the dissolution of carbohydrates in black liquor (BL) during flow-through kraft cooking of Scots pine wood meal (Pinus sylvestris) was studied. Fractions of BL were collected at different times and the carbohydrate content of the various fractions was analysed. Lignin was precipitated from the BL by lowering the pH, and the carbohydrate content of the precipitated lignins (L-prec) was also examined. The molecular weight distribution (MWD) of the L-prec samples was analysed. Xylose (Xyl) was found to be the most predominant sugar in BL aside from arabinose (Ara) and galactose (Gal), while the amounts of these sugars decreased with increasing levels of [Na+] in the cooking liquor. The minor amounts of mannose (Man) found in BL was not influenced by the [Na+]. The effects of NaCl and Na2CO3 on the carbohydrate dissolution were similar, but slightly lower concentrations of Ara and Xyl were found in the case of NaCl application. All of the L-prec samples contained some carbohydrate residues, the contents of which increased with increasing cooking time and decreased with higher [Na+]. It can be concluded that arabinoglucuronoxylan (AGX) along with arabinogalactans (AG) and arabinan, are covalently linked to lignin. The glucose (Glc) residue detected in L-prec may originate from 1,3-beta-glucan linked to lignin.

  • 2. Durruty, Julie
    et al.
    Sewring, Tor
    Schneider, Helen
    Schneider, Lynn
    Mattsson, Tuve
    Theliander, Hans
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. Chalmers University of Technology, Sweden.
    Filtration properties of kraft lignin: The influence of xylan and precipitation conditions2017In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, no 4, p. 508-526Article in journal (Refereed)
    Abstract [en]

    LignoBoost lignin powder was dissolved together with xylan and re-precipitated. The influence of the (i) precipitation temperature, (ii) rate of acidification and (iii) final pH of the slurries on the resulting material and its filtration properties was investigated. In the case of slow acidification, larger agglomerates were obtained for slurries with higher precipitation temperatures as well as with higher ionic strengths. Fast acidification led to a more heterogeneous formation of particles, having a broader particle size distribution, compared to slow acidification. Chemical analysis of different layers of the filter cakes formed revealed that xylan was distributed evenly on the solid lignin, reinforcing the hypothesis that xylan is sorbed onto the lignin agglomerates when precipitated together with lignin. Furthermore, the resulting lignin-xylan mixtures were found to be more difficult to filter in the case of a higher final pH of the slurry (pH 4), close to the pKa values of the carboxylic acid groups of xylan, compared to lower pH values (pH 1-3). This is likely the result of an increase in electrostatic repulsive interactions between the particles/agglomerates at higher pH: a locally more porous solid structure is formed, leading to a larger solid/liquid surface area during filtration.

  • 3.
    Hedlund, Artur
    et al.
    Swerea IVF, Biobased Fibers, Argongatan 30, S-43153 Molndal, Sweden.;Chalmers Univ Technol, Forest Prod & Chem Engn, Gothenburg, Sweden..
    Kohnke, Tobias
    Swerea IVF, Biobased Fibers, Argongatan 30, S-43153 Molndal, Sweden..
    Hagman, Joel
    Lund Univ, Phys Chem, Box 124, S-22100 Lund, Sweden..
    Olsson, Ulf
    Lund Univ, Phys Chem, Box 124, S-22100 Lund, Sweden..
    Theliander, Hans
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Chalmers Univ Technol, Forest Prod & Chem Engn, Gothenburg, Sweden.;Chalmers Univ Technol, .
    Microstructures of cellulose coagulated in water and alcohols from 1-ethyl-3-methylimidazolium acetate: contrasting coagulation mechanisms2019In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, no 3, p. 1545-1563Article in journal (Refereed)
    Abstract [en]

    Coagulation of cellulose solutions is a process whereby many useful materials with variable microstructures and properties can be produced. This study investigates the complexity of the phase separation that generates the structural heterogeneity of such materials. The ionic liquid, 1-ethyl-3-methylimidazolium acetate ([C(2)mim][OAc]), and a co-solvent, dimethylsulfoxide (DMSO), are used to dissolve microcrystalline cellulose in concentrations from 5 to 25wt%. The solutions are coagulated in water or 2-propanol (2PrOH). The coagulated material is then washed and solvent exchanged (water2PrOHbutanonecyclohexane) in order to preserve the generated microstructures upon subsequent drying before analysis. Sweep electron microscopy images of 50k magnification reveal open-pore fibrillar structures. The crystalline constituents of those fibrils are estimated using wide-angle X-ray spectroscopy and specific surface area data. It is found that the crystalline order or crystallite size is reduced by an increase in cellulose concentration, by the use of the co-solvent DMSO, or by the use of 2PrOH instead of water as the coagulant. Because previous theories cannot explain these trends, an alternative explanation is presented here focused on solid-liquid versus liquid-liquid phase separations. [GRAPHICS] .

  • 4.
    Jedvert, Kerstin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. Chalmers, Dept Forest Prod & Chem Engn, SE-41296 Gothenburg, Sweden..
    Saltberg, Anna
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. Chalmers, Dept Forest Prod & Chem Engn, SE-41296 Gothenburg, Sweden..
    Lindström, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Theliander, Hans
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. Chalmers, Dept Forest Prod & Chem Engn, SE-41296 Gothenburg, Sweden.
    EXTRACTION OF HEMI-CELLULOSES AFTER CHEMICAL PRETREATMENT COMBINED WITH MILD STEAM EXPLOSION2011In: 16TH INTERNATIONAL SYMPOSIUM ON WOOD, FIBER AND PULPING CHEMISTRY, PROCEEDINGS, VOLS I & II / [ed] Wang, L Kuang, S Hou, Q Cao, C Si, CL Zhang, HJ, CHINA LIGHT INDUSTRY PRESS , 2011, p. 867-871Conference paper (Refereed)
    Abstract [en]

    The aim of this research is to separate different wood components from softwood as a first step towards development of novel materials made from Scandinavian wood. The approach is pre-treatment with a reducing agent in combination with mild steam explosion (T< 160 degrees C, t < 15 min); followed by extraction with different liquors. The aim is to retain an increased amount of hemicelluloses in general, and glucomannans in particular, during chemical treatments, preferably of high molecular weight. Experiments were performed on wood chips from spruce in small scale steam explosion equipment. A pre-treatment method with sodium borohydride (NaBH4) as a reducing agent model substance was chosen. Wood chips pre-treated with NaBH4 were compared to untreated chips, and the chips were treated with steam explosion followed by extraction in alkali. Results showed that a higher amount of glucomannan was retained in chips treated with NaBH4 than in untreated chips. An increase in the extraction rate as an effect of steam explosion indicates a possible combination of chemical reactions that breaks up the lignin-polysaccharide network and a more porous wood structure. An experimental series with wood powder as raw material were also performed in order to study the chemical reactions during steam explosion, e. g. autohydrolysis. Water impregnated wood powder as well as wood powder treated with NaBH4 was subjected to mild steam explosion for different retention times. It was shown that a decrease in hemicelluloses content occurred after only 5 min, and the degradation was more severe at longer residence times. However, the degradation of hemicelluloses was not as severe as in the chemical treatments at conditions corresponding to chemical pulping, and consequently might be a more prudent method to access the wood structure. Extractions after steam explosion were investigated at different pH levels, and the results showed that most of the glucomannan was still in the wood residue at the tested conditions. The stabilization of glucomannans by pre-treatment with NaBH4 was clearly seen also in these experiments.

  • 5. Sewring, T.
    et al.
    Zhu, W.
    Sedin, M.
    Theliander, Hans
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Predictions of Pair Interaction Potentials between Kraft Lignin Macromolecules in Black Liquors by Utilization of a Modified Poisson-Boltzmann Approach2019In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 58, no 8, p. 3427-3439Article in journal (Refereed)
    Abstract [en]

    In this investigation, a modified Poisson-Boltzmann approach has been used to estimate the mean ion concentration distributions of ionic species present in black liquors around charged kraft lignin macromolecules at industrially relevant conditions. The distributions were utilized to predict the double layer repulsion and, further, predict the overall pair interaction potentials between two kraft lignin macromolecules or particles immersed in the black liquor electrolyte. The properties of softwood black liquors were used as input data to the model. The numerical results predicted the pair interaction potentials to remain repulsive up to salt concentrations of about 2.5 M at pOH 1. The critical coagulation concentration of salt was predicted to decrease as the pOH of the black liquor was increased. The predictions at 65 °C and moderate levels of pOH (3.5) and salt concentration (1.9 M) were found to be in good agreement with previous observations reported in the literature.

  • 6.
    Sewring, Tor
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Chalmers Univ Technol, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden.;Chalmers Univ Technol, .
    Durruty, Julie
    Chalmers Univ Technol, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden..
    Schneider, Lynn
    Chalmers Univ Technol, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden..
    Schneider, Helen
    Chalmers Univ Technol, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden..
    Mattsson, Tuve
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Chalmers Univ Technol, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden.;Chalmers Univ Technol, .
    Theliander, Hans
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Chalmers Univ Technol, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden.;Chalmers Univ Technol, .
    Acid Precipitation of Kraft Lignin from Aqueous Solutions: The Influence of pH, Temperature, and Xylan2019In: Journal of wood chemistry and technology, ISSN 0277-3813, E-ISSN 1532-2319, Vol. 39, no 1, p. 1-13Article in journal (Refereed)
    Abstract [en]

    In this study, the manners in which temperature (45-77 degrees C) and the addition of xylan (5 g/95 g lignin) influence the onset of precipitation and evolution of the particle size distribution during acid precipitation of softwood kraft lignin were investigated in situ. No systematic trend between the onset pH of precipitation and the temperature or the addition of xylan could be observed at these conditions: the average onset pH was found to be 9.3. However, the size of the agglomerates increased as the temperature was increased, but added xylan rendered a decrease in agglomerate size. A higher onset pH was measured at increased Na ion concentration. The results indicate that the ionization degree of the phenolic groups influences the precipitation at 1 M Na ions but it is also probable that the degree of ionization of the carboxylic groups (on kraft lignin and xylan) influences precipitation (particle numbers and sizes).

  • 7.
    Sewring, Tor
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Chalmers Univ Technol, Dept Chem & Chem Engn, Forest Prod & Chem Engn, SE-41296 Gothenburg, Sweden.;Chalmers Univ Technol, Wallenberg Wood Sci Ctr, Royal Inst Technol, Kemigarden 4, SE-41296 Gothenburg, Sweden..
    Theliander, Hans
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Chalmers Univ Technol, Dept Chem & Chem Engn, Forest Prod & Chem Engn, SE-41296 Gothenburg, Sweden.;Chalmers Univ Technol, Wallenberg Wood Sci Ctr, Royal Inst Technol, Kemigarden 4, SE-41296 Gothenburg, Sweden..
    Acid precipitation of kraft lignin from aqueous solutions: the influence of anionic specificity and concentration level of the salt2019In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 73, no 10, p. 937-945Article in journal (Refereed)
    Abstract [en]

    In this study, the formation of particles and evolution of the particle size distribution in the micron range were monitored in situ during acid precipitation of kraft lignin. The objective of this work was to study the influence of anionic specificity and the ion concentration level. The concentrations of ions in the solution were altered both in terms of the concentration of Na+ and the type of anion in the salt added (SO42- and Cl-). The results indicate that a salting-out phenomenon occurred as NaCl was added (Na+ >= 2 mol kg(-1) water) to the kraft lignin solution at high pH, but not when Na2SO4 was added. However, the onset pH of the formation of particles (>= 1 mu m), triggered by acidification, showed to be virtually non-specific to the anion but strongly dependent on the Na+ concentration. As the pH decreased further to below the onset pH of the formation of particles >= 1 mu m, the chord length distributions (particle-size related) indicated that most of the volume of the precipitated kraft lignin (and thus possibly also the mass) may be found among the micron-sized particles, despite the fact that a relatively large number of submicron particles may also be present. The volumebased distributions tended to be wide at relatively low pH and high Na' concentrations (e.g. pH 9.4 and 2.0 mol kg(-1) water).

  • 8.
    Wetterling, John
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Department of Chemistry and Chemical Engineering, Chalmers University of Technology.
    Jonsson, S.
    Department of Chemistry and Chemical Engineering, Chalmers University of Technology.
    Mattsson, Tuve
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Department of Chemistry and Chemical Engineering, Chalmers University of Technology.
    Theliander, Hans
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Department of Chemistry and Chemical Engineering, Chalmers University of Technology.
    The Influence of Ionic Strength on the Electroassisted Filtration of Microcrystalline Cellulose2017In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 56, no 44, p. 12789-12798Article in journal (Refereed)
    Abstract [en]

    The production of materials such as microfibrillated cellulose and cellulose nanocrystals is gathering significant research interest by combining mechanical strength and toughness with a low density, biodegradability and renewability. However, one of the challenges with production on an industrial scale is to obtain an energy-efficient solid-liquid separation which is difficult because of the high specific filtration resistance of these materials. This study investigates electroassisted filtration as a method to facilitate the dewatering of cellulosic materials and the influence of ionic strength on the electrofiltration behavior. Electroassisted filtration is found to improve the dewatering rate of the studied cellulosic material, and the potential improvement compared to pressure filtration increased with the specific surface area of the solid material. Increasing the ionic strength of the system increased the power demand of the electroassisted filtration, and the major potential for industrial application is thus for systems with a limited ionic strength.

  • 9.
    Wetterling, Jonas
    et al.
    KTH. Chalmers Univ Technol, Dept Chem & Chem Engn, S-41296 Gothenburg, Sweden.;Chalmers Univ Technol, Royal Inst Technol, Wallenberg Wood Sci Ctr, S-10044 Stockholm, Sweden..
    Sahlin, Karin
    KTH. Chalmers Univ Technol, Dept Chem & Chem Engn, S-41296 Gothenburg, Sweden.;Chalmers Univ Technol, Royal Inst Technol, Wallenberg Wood Sci Ctr, S-10044 Stockholm, Sweden..
    Mattsson, Tuve
    KTH. Chalmers Univ Technol, Dept Chem & Chem Engn, S-41296 Gothenburg, Sweden.;Chalmers Univ Technol, Royal Inst Technol, Wallenberg Wood Sci Ctr, S-10044 Stockholm, Sweden..
    Westman, Gunnar
    KTH. Chalmers Univ Technol, Dept Chem & Chem Engn, S-41296 Gothenburg, Sweden.;Chalmers Univ Technol, Royal Inst Technol, Wallenberg Wood Sci Ctr, S-10044 Stockholm, Sweden..
    Theliander, Hans
    KTH. Chalmers Univ Technol, Dept Chem & Chem Engn, S-41296 Gothenburg, Sweden.;Chalmers Univ Technol, Royal Inst Technol, Wallenberg Wood Sci Ctr, S-10044 Stockholm, Sweden..
    Electroosmotic dewatering of cellulose nanocrystals2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 4, p. 2321-2329Article in journal (Refereed)
    Abstract [en]

    One of the main challenges for industrial production of cellulose nanocrystals is the high energy demand during the dewatering of dilute aqueous suspensions. It is addressed in this study by utilising electroosmotic dewatering to increase the solid content of suspensions of cellulose nanocrystals. The solid content was increased from 2.3 up to 15.3 wt%, i.e. removal of more than 85% of all the water present in the system, at a much lower energy demand than that of thermal drying. Increasing the strength of the electric field increased not only the dewatering rate but also the specific energy demand of the dewatering operation: the electric field strength used in potential industrial applications is thus a trade-off between the rate of dewatering and the energy demand. Additionally, it was found that high local current intensity had the potential of degrading cellulose nanocrystals in contact with the anode. The maximum strength of the electric field applied should therefore be limited depending on the equipment design and the suspension conditions.

1 - 9 of 9
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf