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  • 1.
    Aminzadeh, Selda
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Haghniaz, R.
    Ottenhall, A.
    Sevastyanova, Olena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Lindström, E.
    Khademhosseini, A.
    Lignin based hydrogel for the antibacterial applicationManuscript (preprint) (Other academic)
  • 2.
    Aminzadeh, Selda
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lauberts, M.
    Dobele, G.
    Ponomarenko, J.
    Mattsson, T.
    Lindström, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Membrane filtration of kraft lignin: Structural charactristics and antioxidant activity of the low-molecular-weight fraction2018In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 112, p. 200-209Article in journal (Refereed)
    Abstract [en]

    Lignin, which is the second most abundant biomass component and has carbon-rich phenolic content, is a promising renewable raw material for multiple applications, such as carbon fibers, adhesives, and emulsifiers. To use lignin efficiently, it is important to ensure its purity and homogeneity. As a result, the separation of lignin into fractions with high purity and narrow molecular-weight distributions is likely a prerequisite for several applications. Ultrafiltration using ceramic membranes has many advantages, including enabling direct lignin extraction from Kraft pulp cooking liquors without pH and temperature adjustment. One challenge with membrane filtration using such a system is the potential for reduced membrane performance over time, which is associated with fouling. In this study, LignoBoost Kraft lignin was fractionated using a ceramic membrane with a molecular weight cut-off of 1 kDa. The separation behavior during ultrafiltration fractionation was investigated and the antioxidant properties of the recovered low-molecular-weight (low-MW) lignin samples were evaluated. Using this model system, the permeate fluxes were unstable during the 100 h of membrane operation. However, a decrease in the average MW in the permeate over time was observed. The shift in MW was most pronounced for virgin membranes, while a more stable MW distribution was evident for membranes subjected to multiple cleaning cycles. According to 2D NMR analysis, low-MW lignin that was recovered after 100 h of operation, consisted of smaller lignin fragments, such as dimers and oligomers, with a high content of methoxy-groups. This was confirmed using the size exclusion chromatography method, which indicated an weigh average molecular weight in the range of 450–500 Da. 31P NMR spectroscopy showed that, despite the lower total content of phenolic OH groups, the low-MW sample had a higher proportion of non-condensed phenolic OH groups. The results of the antioxidant tests demonstrated the strong potential of lignin and its low-MW fraction as a natural antioxidant, particularly for lipid-containing systems. The low-MW lignin fraction showed better antioxidant activity than the non-fractionated LignoBoost lignin in the kinetic oxygen radical absorbance capacity (ORAC) test and demonstrated three-fold stronger inhibition of the substrate (fluorescein) than the reference antioxidant Trolox (a water-soluble derivative of vitamin E).

  • 3.
    Budnyak, Tetyana
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Aminzadeh, Selda
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Wallenberg Wood Science Center.
    Pylypchuk, Ievgen
    Department of Molecular Sciences, Swedish University of Agricultural Sciences (SLU), Allmas alle 5, SE-750 07 Uppsala, Swede.
    Riazanova, Anastasiia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Tertykh, Valentin
    Chuiko Institute of Surface Chemistry, National Academy of Sciences of Ukraine, 17 General Naumov Str., 03164 Kyiv, Ukraine.
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Sevastyanova, Olena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Peculiarities of synthesis and properties of lignin-silica nanocomposites prepared by sol-gel method2018In: Nanomaterials, Vol. 8, no 11, p. 1-18Article in journal (Refereed)
    Abstract [en]

    The development of advanced hybrid materials based on polymers from biorenewable sources and mineral nanoparticles is currently of high importance. In this paper, we applied softwood kraft lignins for the synthesis of lignin/SiO2 nanostructured composites. We described the peculiarities of composites formation in the sol-gel process through the incorporation of the lignin into a silica network during the hydrolysis of tetraethoxysilane (TEOS). The initial activation of lignins was achieved by means of a Mannich reaction with 3-aminopropyltriethoxysilane (APTES). In the study, we present a detailed investigation of the physicochemical characteristics of initial kraft lignins and modified lignins on each step of the synthesis. Thus, 2D-NMR, 31P-NMR, size-exclusion chromatography (SEC) and dynamic light scattering (DLS) were applied to analyze the characteristics of pristine lignins and lignins in dioxan:water solutions. X-Ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) were used to confirm the formation of the lignin–silica network and characterize the surface and bulk structures of the obtained hybrids. Termogravimetric analysis (TGA) in nitrogen and air atmosphere were applied to a detailed investigation of the thermal properties of pristine lignins and lignins on each step of modification. SEM confirmed the nanostructure of the obtained composites. As was demonstrated, the activation of lignin is crucial for the sol-gel formation of a silica network in order to create novel hybrid materials from lignins and alkoxysilanes (e.g., TEOS). It was concluded that the structure of the lignin had an impact on its reactivity during the activation reaction, and consequently affected the properties of the final hybrid materials.

  • 4.
    Budnyak, Tetyana M.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Natl Acad Sci Ukraine, Chuiko Inst Surface Chem, 17 Gen Naumov Str, UA-03164 Kiev, Ukraine..
    Aminzadeh, Selda
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Pylypchuk, Ievgen V.
    Swedish Univ Agr Sci SLU, Dept Mol Sci, Allmas Alle 5, SE-75007 Uppsala, Sweden..
    Sternik, Dariusz
    Marie Curie Sklodowska Univ, 2 M Curie Sklodowska Sq, PL-20031 Lublin, Poland..
    Tertykh, Valentin A.
    Natl Acad Sci Ukraine, Chuiko Inst Surface Chem, 17 Gen Naumov Str, UA-03164 Kiev, Ukraine..
    Lindström, Mikael E.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Sevastyanova, Olena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Methylene Blue dye sorption by hybrid materials from technical lignins2018In: Journal of Environmental Chemical Engineering, ISSN 2160-6544, E-ISSN 2213-3437, Vol. 6, no 4, p. 4997-5007Article in journal (Refereed)
    Abstract [en]

    New hybrid sorbents were synthesized from technical lignins and silica and were applied for the removal of Methylene Blue dye (MB) from aqueous solution. Kraft softwood lignins from LignoBoost (LBL) and CleanFlowBlack (CFBL) processes were used to understand the influence of molecular weight and functionality of initial lignins on the properties of the final hybrids. The synthesized materials were applied as adsorbents for the removal of MB from aqueous solutions. The effects of parameters such as contact time, initial concentration of dye and initial pH on the adsorption capacity were evaluated. The hybrids exhibited higher adsorption capacity than the initial macromolecules of lignin with respect to MB. The hybrid based on CFBL exhibited an adsorption capacity of 60 mg/g; this value was 30% higher than the capacity of the hybrid based on LBL, which was 41.6 mg/g. Lignin hybrid materials extract 80-99% of the dye in a pH range from 3 to 10. The equilibrium and kinetic characteristics of MB uptake by the hybrids followed the Langmuir isotherm model and pseudosecond-order model, rather than the Freundlich and Temkin models, the pseudo-first-order or the intraparticle diffusion model. The attachment of the dye to the hybrid surface was confirmed via FE-SEM and FTIR spectroscopy. The mechanism for MB adsorption was proposed. Due to the high values of regeneration efficiency of the surface of both lignin-silica hybrid materials in 0.1 M HCl (up to 75%) and ethanol (99%), they could be applied as effective sorbents in industrial wastewater treatment processes.

  • 5.
    de Carvalho, Danila Morais
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, Stockholm, Sweden.;Univ Fed Vicosa, Vicosa, MG, Brazil..
    Martinez-Abad, Antonio
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, Stockholm, Sweden..
    Colodette, Jorge Luiz
    Univ Fed Vicosa, Vicosa, MG, Brazil..
    Lindström, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, Stockholm, Sweden..
    Vilaplana, Francisco
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, Stockholm, Sweden..
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Fibre Wood Tech Wood Chem Pulp Tech, Stockholm, Sweden..
    Chemical and structural characterization of xylans from sugarcane bagasse and sugarcane straw2016In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 251Article in journal (Other academic)
  • 6.
    de Carvalho, Danila Morais
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Moser, Carl
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Sevastyanova, Olena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Impact of the chemical composition of cellulosic materials on the nanofibrillation process and nanopaper properties2019In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 127, p. 203-211Article in journal (Refereed)
    Abstract [en]

    This paper investigated the impact of the amounts of lignin and hemicelluloses on cellulose nanofibers (CNFs). Birch and spruce wood were used to prepare holocellulose and cellulose samples by classical methods. To better assess the effect of the chemical composition on the CNF performance and simplify the process for CNF preparation, no surface derivatization method was applied for CNF preparation. Increased amounts of hemicelluloses, especially mannans, improved the defibration process, the stability of the CNFs and the mechanical properties, whereas the residual lignin content had no significant effect on these factors. On the other hand, high lignin content turned spruce nanopapers yellowish and, together with hemicelluloses, reduced the strain-at-break values. Finally, when no surface derivatization was applied to holocellulose and cellulose samples before defibration, the controlled preservation of residual lignin and hemicelluloses on the CNFs indicate to be crucial for the process. This simplified method of CNF preparation presents great potential for forest-based industries as a way to use forestry waste (e.g., branches, stumps, and sawdust) to produce CNFs and, consequently, diversify the product range and reach new markets.

  • 7. de Carvalho, Danila Morais
    et al.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    de Queiroz, Jose Humberto
    Colodette, Jorge Luiz
    Cold alkaline extraction as a pretreatment for bioethanol production from eucalyptus, sugarcane bagasse and sugarcane straw2016In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 124, p. 315-324Article in journal (Refereed)
    Abstract [en]

    Optimal conditions for the cold alkaline extraction (CAE) pretreatment of eucalyptus, sugarcane bagasse and sugarcane straw are proposed in view of their subsequent bioconversion into ethanol through the semi -simultaneous saccharification and fermentation (SSSF) process (with presaccharification followed by simultaneous saccharification and fermentation, or SSF). The optimum conditions, which are identified based on an experiment with a factorial central composite design, resulted in the removal of 46%, 52% and 61% of the xylan and 15%, 37% and 45% of the lignin for eucalyptus, bagasse and straw, respectively. The formation of pseudo-extractives was observed during the CAE of eucalyptus. Despite the similar glucose concentration and yield for all biomasses after 12 h of presaccharification, the highest yield (0.065 g(ethanol)/g(biomass)), concentrations (5.74 g L-1) and volumetric productivity for ethanol (0.57 g L-1 h(-1)) were observed for the sugarcane straw. This finding was most likely related to the improved accessibility of cellulose that resulted from the removal of the largest amount of xylan and lignin.

  • 8. Galysh, V.
    et al.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Deartel, M.
    Lindström, Mikael E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Gornikov, Yu.
    Impact of ferrocyanide salts on the thermo-oxidative degradation of lignocellulosic sorbents2017In: Journal of thermal analysis and calorimetry (Print), ISSN 1388-6150, E-ISSN 1588-2926, Vol. 128, no 2, p. 1019-1025Article in journal (Refereed)
    Abstract [en]

    The catalytic effect of ferrocyanide salts of d-metals on the thermo-oxidative degradation of lignocellulose-inorganic sorbents derived from apricot seed shells was investigated by differential thermal analysis. A comparative analysis of the thermal characteristics of the apricot seed shells and the lignocellulose matrix obtained from the shells by alkali-acid pretreatment was performed. It was shown that acid-alkali pretreatment of the apricot seed shells increases the thermal stability of the lignocellulosic material, due to the removal of low molecular weight carbohydrates and other components. The thermal degradation process of the lignocellulose-inorganic samples containing different ferrocyanides occurred at lower temperatures than the initial lignocellulose matrix, indicating the catalytic activity of modifiers. It was demonstrated that for the sorbents containing mixed salts of potassium cobalt and potassium nickel ferrocyanide, thermal destruction ends at temperatures that are 60 A degrees C lower than those for the initial lignocellulose matrix. The obtained results also show that the thermal destruction of composite lignocellulose-inorganic sorbents can be a suitable method for their disposal.

  • 9.
    Goliszek, M.
    et al.
    Marie Curie Sklodowska Univ, Fac Chem, Maria Curie Sklodowska Sq 3, PL-20031 Lublin, Poland..
    Podkoscielna, B.
    Marie Curie Sklodowska Univ, Fac Chem, Maria Curie Sklodowska Sq 3, PL-20031 Lublin, Poland..
    Fila, K.
    Marie Curie Sklodowska Univ, Fac Chem, Maria Curie Sklodowska Sq 3, PL-20031 Lublin, Poland..
    Riazanova, A. V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Aminzadeh, Selda
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Sevastyanova, O.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Gun'ko, V. M.
    Chuiko Inst Surface Chem, 17 Gen Naumov Str, UA-03164 Kiev, Ukraine..
    Synthesis and structure characterization of polymeric nanoporous microspheres with lignin2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 10, p. 5843-5862Article in journal (Refereed)
    Abstract [en]

    Nanoporous microspheres with divinylbenzene (DVB), styrene (St), and lignin were synthesized by an emulsion-suspension polymerization method. Several types of lignins were used: (1) kraft lignin before (L-unmod) and after modification with methacryloyl chloride (L-Met) and (2) low-molecular-weight kraft lignin unmodified (LWL-unmod) and modified with methacrylic anhydride (LWL-Met). LWL was prepared by ultrafiltration of industrial black liquor using a ceramic membrane with a molecular weight (Mw) cut-off of 5 kDa. The synthesis was optimized by addition of different amounts of lignins. The microsphere texture was characterized using low-temperature nitrogen adsorption and small angle X-ray scattering analyses. The microspheres were nano- and mesoporous with a specific surface area in the range of 0.1-409 m(2)/g. The morphology of the copolymers was studied using field emission scanning electron microscopy and atomic force microscopy. The thermal properties were studied using differential scanning calorimetry and thermogravimetric analysis methods. A significant difference in the microsphere roughness is affected by lignins due to the presence of lignin nanoparticles at the surface of the microspheres. Molecular modeling was used to predict the sorption properties of the copolymers affected by various fields around the particles. The particle size, polydispersity and zeta potential of the St + DVB, L-Met + St + DVB and L-unmod + St + DVB samples were measured by dynamic light scattering. Additionally, the point of zero charge of the samples was determined using potentiometric titration. The materials studied have a great potential for sorption processes due to their developed porosity and the presence of a number of active surface functionalities. [GRAPHICS] .

  • 10.
    Goliszek, M.
    et al.
    Marie Curie Sklodowska Univ, Dept Polymer Chem, M Curie Sklodowska Sq 5, PL-20031 Lublin, Poland..
    Podkoscielna, B.
    Marie Curie Sklodowska Univ, Dept Polymer Chem, M Curie Sklodowska Sq 5, PL-20031 Lublin, Poland..
    Sevastyanova, Olena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Fila, K.
    Marie Curie Sklodowska Univ, Dept Polymer Chem, M Curie Sklodowska Sq 5, PL-20031 Lublin, Poland..
    Chabros, A.
    Marie Curie Sklodowska Univ, Dept Polymer Chem, M Curie Sklodowska Sq 5, PL-20031 Lublin, Poland..
    Paczkowski, P.
    Marie Curie Sklodowska Univ, Dept Polymer Chem, M Curie Sklodowska Sq 5, PL-20031 Lublin, Poland..
    Investigation of accelerated aging of lignin-containing polymer materials2019In: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 123, p. 910-922Article in journal (Refereed)
    Abstract [en]

    This paper presents the results of an accelerated aging test of biocomposites containing kraft lignin, where the resistance of the materials against humidity and light exposure was investigated. Low molecular weight lignin, modified with methacrylic anhydride (LWL-Met), was copolymerized with two commercial monomers: styrene (St) and methyl methacrylate (MMA). The biocomposites were obtained by a bulk polymerization method using alpha,alpha'-azoiso-bis-butyronitrile (AIBN) as a free radical polymerization initiator. The Shore D hardness of the obtained materials was determined before and after aging test. The changes in the chemical structures of polymers, as the result of aging were analyzed by using the attenuated total reflection Fourier transform infrared (ATR/FT-IR) spectroscopy method. The thermal behavior and stability of the obtained materials were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The surface topography was determined using the optical topography method to evaluate the changes on the surface of synthesized materials resulted from accelerated aging. Application of modified lignin as a biocomponent in the polymerization process and its influence on the properties of the obtained materials before and after the accelerated aging test are discussed.

  • 11. Gordobil, O.
    et al.
    Moriana, Rosana
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Zhang, Liming
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Labidi, J.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Assesment of technical lignins for uses in biofuels and biomaterials: Structure-related properties, proximate analysis and chemical modification2016In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 83, p. 155-165Article in journal (Refereed)
    Abstract [en]

    The potential of organosolv and kraft eucalyptus and spruce lignin as feedstock for polymeric materials and biofuel applications was assessed. Proximate analysis was used to predict the heating values and char formation. Chemical modification, based on the esterification reaction with methacryloyl chloride, was applied to introduce vinyl groups into the lignin macromolecules for enhanced reactivity. Kraft eucalyptus and spruce lignins had a more condensed structure than organosolv lignins, which resulted in greater thermal stability for these lignins. For different species within the same process, the thermal parameters showed a correlation with certain structural and compositional parameters (ash and sugars content, molecular weight and degree of condensation). Organosolv spruce lignin produced the highest heating value of 24. MJ/Kg, which is suitable for biofuel applications. The content of phenolic OH groups was higher for kraft lignins and especially higher for softwood lignins, both organosolv and kraft. The degree of methacrylation, estimated from the content of vinyl groups per C9 lignin unit, was significantly greater for organosolv lignins than for kraft lignins despite the higher OH-groups content in the latter.

  • 12.
    Halysh, Vita
    et al.
    Igor Sikorsky Kyiv Polytech Inst, Fac Chem Engn, Dept Ecol & Technol Plant Polymers, Peremogy Avenu 37-4, UA-03056 Kiev, Ukraine.;Natl Acad Sci Ukraine, OO Chuiko Inst Surface Chem, Gen Naumov Str 17, UA-03164 Kiev, Ukraine..
    Sevastyanova, Olena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Riazanova, Anastasia V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Pasalskiy, Bogdan
    Kyiv Natl Univ Trade & Econ, Kyoto Str 19, UA-02156 Kiev, Ukraine..
    Budnyak, Tetyana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Natl Acad Sci Ukraine, OO Chuiko Inst Surface Chem, Gen Naumov Str 17, UA-03164 Kiev, Ukraine..
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Kartel, Mykola
    Natl Acad Sci Ukraine, OO Chuiko Inst Surface Chem, Gen Naumov Str 17, UA-03164 Kiev, Ukraine..
    Walnut shells as a potential low-cost lignocellulosic sorbent for dyes and metal ions2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 8, p. 4729-4742Article in journal (Refereed)
    Abstract [en]

    Currently, it is necessary to develop new methods and materials for solving the problem of environmental pollution by various toxicants. For these purposes, vegetal materials can be used. In this study, efficient low-cost sorbents based on walnut shells, an agro-industrial by-product, were prepared by treatment with acetic acid or a mixture of acetic acid and hydrogen peroxide. It was shown that the treatments significantly affected the composition and structure of walnut shells and their sorption properties with respect to organic dyes (methylene blue, methyl violet, and murexide) and heavy metal ions. Methylene blue dye was used for additional studies on the effect of pH, contact time and kinetics of sorption. The maximum adsorption rate of the dye occurred within the first 30 min of contact, during which the concentration of methylene blue in the solution was reduced by more than half. Full sorption equilibrium was reached within 180-230 min for studied samples. The adsorption kinetics of methylene blue was found to best be described by pseudo-second-order kinetic model. It was shown that dyes adsorption processes were well described by Freundlich model, which takes into consideration the heterogeneity of the surface of the adsorbent. The obtained plant sorbents are characterized by a high sorption capacity for heavy metal ions (18-29 mg/g for Fe3+ and 33-44 mg/g for Cu-2). Due to their numerous advantages, such as the high sorption capacity, high availability and low cost of raw materials, simplicity of disposal and nontoxicity, the obtained natural sorbents may have a wide practical use in industrial wastewater treatment. [GRAPHICS] .

  • 13.
    Han, Tong
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Sophonrat, Nanta
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Tagami, Ayumu
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Sevastyanova, Olena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Mellin, P.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology. KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Characterization of lignin at pre-pyrolysis temperature to investigate its melting problem2019In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 235, p. 1061-1069Article in journal (Refereed)
    Abstract [en]

    Technical lignin particles melt under relatively low temperature. This results in the problem in the continuous feeding and fluidization during lignin pyrolysis, which in turn limits its utilization on a large scale. In this study, two most available types of lignin have been used to investigate the lignin melting problem, which are Kraft lignin (KL) from pulping process and hydrolysis lignin (HL) from bio-ethanol production process. Elemental composition, thermal property and thermally decomposed derivatives of each sample are tested by elemental analyzer, TGA, DSC, and Py-GC/MS. Morphology, structure and crystal change before and after heat treatment are tested by microscopy, FTIR and XRD. All results suggest that lignin structure determines its melting properties. Kraft lignin from pulping process contains a less cross-linked structure. It melts under heating. On the other hand, hydrolysis lignin from hydrolysis process contains a highly crossed-linked and condensed structure. It does not melt before decomposition under heat treatment. Modifying lignin structure is suggested for the resolution of technical lignin melting problem.

  • 14. Lange, H.
    et al.
    Schiffels, P.
    Sette, M.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Crestini, C.
    Fractional Precipitation of Wheat Straw Organosolv Lignin: Macroscopic Properties and Structural Insights2016In: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 4, no 10, p. 5136-5151Article in journal (Refereed)
    Abstract [en]

    Wheat straw organosolv lignin has been thoroughly characterized with respect to bulk material properties, surface properties, and structural characteristics by means of antioxidant assays and determination of the equilibrium constant in water-octanol partitioning, i.e., logP determination, optimized gel permeation chromatography, quantitative 31P NMR spectroscopy, quantitative HSQC measurements, and XPS studies. The material was subsequently fractionally precipitated based on a binary solvent system comprised of n-hexane and acetone to yield four fractions that exhibit distinct molecular mass characteristics, while displaying similar structural characteristics, as revealed by the same set of analysis techniques applied to them. Extensive correlation studies underline the versatility of the obtained fractions as higher quality starting materials for lignin valorization approaches since, for example, glass transition temperatures correlate well with number-average molecular weights, applying the Flory-Fox relation as well as its Ogawa and Loshaek variations.

  • 15.
    Lange, Heiko
    et al.
    Univ Roma Tor Vergata, Dept Chem Sci & Technol, Rome, Italy..
    Sevastyanova, Olena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Crestini, Claudia
    Univ Roma Tor Vergata, Dept Chem Sci & Technol, Rome, Italy..
    Correlating structural features of lignin with physical properties: Toward a descriptive-predictive database2015In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 249Article in journal (Other academic)
  • 16. Lauberts, Maris
    et al.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Ponomarenko, Jevgenija
    Dizhbite, Tatjana
    Dobele, Galina
    Volperts, Alexandr
    Lauberte, Liga
    Telysheva, Galina
    Fractionation of technical lignin with ionic liquids as a method for improving purity and antioxidant activity2017In: INDUSTRIAL CROPS AND PRODUCTS, ISSN 0926-6690, Vol. 95, p. 512-520Article in journal (Refereed)
    Abstract [en]

    Alder soda lignin, a by-product of the chemical processing of black alder wood, was fractionated using ionic liquids (ILs) based on the 1-buthyl-3-methylimidazolium [Bmim] cation and the following anions: chloride ([Bmim]Cl), dimethylphosphate ([Bmim]Me2PO4), acetate ([Brhim]OAc) and tosylate ([Bmim]OTs). The aim was to obtain lignin fractions of improved purity for further application as antioxidants. The purity and properties of the IL lignin fractions were compared with those of other lignin fractions obtained using sequential extraction with organic solvents. The original lignin and the lignin fractions were characterized by analytical pyrolysis (Py-GC/MS/FID), size-permeation chromatography (GPC), electron paramagnetic resonance (EPR) spectroscopy and wet chemistry methods. The lignin treatment with [Bmim]DMP, [Bmim]OAc and [Bmim]OTs produced fractions with a lignin content of 98-99%. These fractions along with the n-propanol and methanol fractions obtained using sequential organic solvent extraction were enriched with certain structural features that had a positive impact on lignin antioxidant activity, according to the results from DPPH center dot and ORAC assays.

  • 17.
    Li, Dongfang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ionic Liquids pretreatment of cellulose fiber materials for improvement of reactivity and value added applications2011In: 16th International Symposium on Wood, Fiber and Pulping Chemistry - Proceedings, ISWFPC , 2011, p. 503-510Conference paper (Refereed)
    Abstract [en]

    Cellulose is one of the most abundant biological and renewable materials in the world. The application of cellulose is widely distributed among various industries such as fiber, paper, pharmaceutical, membrane, polymer and paint. However, the utilization of cellulose or cellulosic materials has not been developed entirely because of its poor solubility in common organic solvents. Ionic liquids (ILs) are relatively new family of solvents for dissolution of cellulose. They are organic salts containing cations and anions with low melting temperature, which make them suitable for the solubilization of cellulose. Moreover, ILs are non-volatile, non-toxic, non-flammable and thermally and chemically stable. Cellulose dissolved in ILs can be regenerated with anti-solvents as water, ethanol and acetone. In this study, the pretreatment of both hardwood and softwood dissolving pulps with two ILs ([C4mim+]CH3COO- and [C4mim+]Cl-) were performed. Furthermore, the impact of treating cellulose with ILs was also evaluated by using different analytical techniques, such as size exclusion chromatography (SEC), thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM).

  • 18.
    Li, Dongfang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Pretreatment of softwood dissolving pulp with ionic liquids2012In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 66, no 8, p. 935-943Article in journal (Refereed)
    Abstract [en]

    Few Scandinavian pulp mills produce dissolving pulps; however, the demand on textile fibers is increasing. This study investigates the chemical interaction of dissolving pulp with ionic liquids (ILs), where softwood and hardwood industrial dissolving pulps were pretreated with ILs 1-butyl-3-methyl-imidazolium acetate ([C(4)mim(+)]CH3COO-) and 1-butyl-3-methyl-imdazolium chloride ([C(4)mim(+)]Cl-). Time and temperature dependence of the dissolution process as well as the impact of the pretreatment on the molecular weight properties, thermal stability, morphology, and crystallinity of the cellulose were evaluated by means of size exclusion chromatography (SEC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and solid state nuclear magnetic resonance (NMR). It was shown that the dissolution of cellulosic material in ILs is a temperature-dependent process; however, the viscosity of ILs affected the efficiency of dissolution at a given temperature. Molecular weight properties were affected negatively by increased dissolution temperature, while the type of antisolvent for the regeneration had no major impact on the degree of polymerization of cellulose. Water was more efficient than ethanol for the regeneration of cellulose when performed at an elevated temperature. The pretreatment decreased the crystallinity of cellulosic material. This might lead to the increased accessibility and reactivity of cellulose.

  • 19.
    Li, Jiebing
    et al.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Sevastyanova, Olena
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Gellerstedt, Göran
    KTH, Superseded Departments, Fibre and Polymer Technology.
    The distribution of oxidizable structures in ECF- and TCF- bleached kraft pulps2002In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 17, no 4, p. 415-419Article in journal (Refereed)
    Abstract [en]

    The kappa number in kraft pulp contains contributions from lignin and from other oxidizable structures denoted as false lignin. The latter can be divided in hexenuronic acid groups and "non-lignin" structures. In this paper, the kappa number units due to the various contributing structures have been quantified by fractionation of the kappa number. Bleached spruce and birch kraft industrial pulps taken after each stage in an ECF (ODEQP) and in a TCF (OQOPQPO) bleaching sequence respectively have been assessed. Possible correlations between the content of false lignin, the pulp origin, the bleaching conditions, and brightness and viscosity values have been sought. It is concluded that the false lignin structures are formed predominantly during the cooking and oxygen delignification stages. The false lignin structures were found to give different responses in the various bleaching stages, but to have no influence on either pulp brightness or viscosity.

  • 20.
    Li, Jiebing
    et al.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Sevastyanova, Olena
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Gellerstedt, Göran
    KTH, Superseded Departments, Fibre and Polymer Technology.
    The relationship between kappa number and oxidizable structures in bleached kraft pulps2002In: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 28, no 8, p. 262-266Article in journal (Refereed)
    Abstract [en]

    The relationship between residual oxidized lignin structures in spruce and birch kraft pulps and their kappa number contribution after each stage in an ODEQP (spruce) and an OQ(OP)Q(PO) (birch) sequence, respectively, has been investigated. Analysis by a modified kappa number method (OxDem kappa number) as well as by determination of permanganate oxidation equivalents on various isolated residual lignin samples revealed that the relationship between the lignin content and kappa number gradually changes as the bleaching sequence proceeds, giving values that differ substantially from that found in unbleached kraft pulp. These effects can be attributed to the successive oxidative fragmentation of aromatic rings and the formation of carboxyl and non-aromatic unsaturated structures in the residual lignin structure. Therefore, a kappa number determination on pulp which has been subjected to an oxidative stage will result in an underestimation of the lignin content.

  • 21. Mattsson, Tuve
    et al.
    Azhar, Shoaib
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Eriksson, Susanna
    Helander, Mikaela
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Jedvert, Kerstin
    Lawoko, Martin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lindström, Mikael E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    McKee, Lauren S.
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Oinonen, Petri
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Westerberg, Niklas
    Theliander, Hans
    The Development of a Wood-based Materials-biorefinery2017In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, no 4, p. 9152-9182Article in journal (Refereed)
    Abstract [en]

    Several different methods for the extraction, separation, and purification of wood constituents were combined in this work as a unified process with the purpose of achieving a high overall efficiency of material extraction and utilization. This study aimed to present a laboratory-scale demonstrator biorefinery that illustrated how the different wood constituents could be separated from the wood matrix for later use in the production of new bio-based materials and chemicals by combining several approaches. This study builds on several publications and ongoing activities within the Wallenberg Wood Science Center (WWSC) in Sweden on the theme "From wood to material components." Combining the approaches developed in these WWSC projects - including mild steam explosion, membrane and chromatographic separation, enzymatic treatment and leaching, ionic liquid extraction, and fractionation together with Kraft pulping - formed an outline for a complete materials-biorefinery. The process steps involved were tested as integral steps in a linked process. The scale of operations ranged from the kilogram-scale to the gram-scale. The feasibility and efficiency of these process steps in a biorefinery system were assessed, based on the data, beginning with whole wood.

  • 22.
    Morais de Carvalho, Danila
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Abad, Antonio Martinez
    KTH, School of Biotechnology (BIO), Glycoscience.
    Evtuguin, D. V.
    Colodette, J. L.
    Lindström, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Vilaplana, Francisco
    KTH, School of Biotechnology (BIO), Glycoscience.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Isolation and characterization of acetylated glucuronoarabinoxylan from sugarcane bagasse and straw2017In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 156, p. 223-234Article in journal (Refereed)
    Abstract [en]

    Sugarcane bagasse and straw are generated in large volumes as by-products of agro-industrial production. They are an emerging valuable resource for the generation of hemicellulose-based materials and products, since they contain significant quantities of xylans (often twice as much as in hardwoods). Heteroxylans (yields of ca 20% based on xylose content in sugarcane bagasse and straw) were successfully isolated and purified using mild delignification followed by dimethyl sulfoxide (DMSO) extraction. Delignification with peracetic acid (PAA) was more efficient than traditional sodium chlorite (NaClO2) delignification for xylan extraction from both biomasses, resulting in higher extraction yields and purity. We have shown that the heteroxylans isolated from sugarcane bagasse and straw are acetylated glucuronoarabinoxylans (GAX), with distinct molecular structures. Bagasse GAX had a slightly lower glycosyl substitution molar ratio of Araf to Xylp to (0.5:10) and (4-O-Me)GlpA to Xylp (0.1:10) than GAX from straw (0.8:10 and 0.1:10 respectively), but a higher degree of acetylation (0.33 and 0.10, respectively). A higher frequency of acetyl groups substitution at position α-(1 → 3) (Xyl-3Ac) than at position α-(1 → 2) (Xyl-2Ac) was confirmed for both bagasse and straw GAX, with a minor ratio of diacetylation (Xyl-2,3Ac). The size and molecular weight distributions for the acetylated GAX extracted from the sugarcane bagasse and straw were analyzed using multiple-detection size-exclusion chromatography (SEC-DRI-MALLS). Light scattering data provided absolute molar mass values for acetylated GAX with higher average values than did standard calibration. Moreover, the data highlighted differences in the molar mass distributions between the two isolation methods for both types of sugarcane GAX, which can be correlated with the different Araf and acetyl substitution patterns. We have developed an empirical model for the molecular structure of acetylated GAX extracted from sugarcane bagasse and straw with PAA/DMSO through the integration of results obtained from glycosidic linkage analysis, 1H NMR spectroscopy and acetyl quantification. This knowledge of the structure of xylans in sugarcane bagasse and straw will provide a better understanding of the isolation-structure-properties relationship of these biopolymers and, ultimately, create new possibilities for the use of sugarcane xylan in high-value applications, such as biochemicals and bio-based materials. © 2016 Elsevier Ltd

  • 23.
    Moraisde Carvalho, Danila
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. Univ Fed Vicosa, Dept Forestry Engn, Pulp & Paper Lab, BR-36570900 Vicosa, MG, Brazil.
    Martinez Abad, Antonio
    KTH, School of Biotechnology (BIO), Glycoscience.
    Colodette, Jorge Luiz
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lindström, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Vilaplana, Fransisco
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Comparative characterization of acetylated heteroxylan from eucalyptus, sugarcane bagasse and sugarcane strawManuscript (preprint) (Other academic)
  • 24.
    Moraisde Carvalho, Danila
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. Univ Fed Vicosa, Dept Forestry Engn, Pulp & Paper Lab, BR-36570900 Vicosa, MG, Brazil.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Penna, Lais Souza
    da Silva, Brunela Pereira
    Lindstrom, Mikael E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Colodette, Jorge Luiz
    Assessment of chemical transformations in eucalyptus, sugarcane bagasse and straw during hydrothermal, dilute acid, and alkaline pretreatments2015In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 73, p. 118-126Article in journal (Refereed)
    Abstract [en]

    The impact of hydrothermal, dilute acid, and alkaline pretreatments on the chemical structure of eucalyptus, sugarcane bagasse, and straw were compared with a view to their subsequent bioconversion into ethanol. Sugarcane bagasse and straw contain high amounts of extractives (15.0% and 12.2%, respectively), ash (2.3% and 7.9%, respectively), and silica (1.4% and 5.8%, respectively). If not properly corrected, the presence of silica would lead to the overestimation of the lignin, while high amounts of extractives would cause the overestimation of the content of sugars in biomass. Applying a novel approach through the use of complete mass balance, bagasse and straw were proven to contain lower amounts of lignin (18.0% and 13.9%, respectively) than previously reported for these raw materials, and certainly a much lower amount of lignin than eucalyptus (27.4%). The syringyl to guaiacyl units ratio (SIG) for lignin in bagasse and straw (1.1 and 0.5, respectively) was lower than that for eucalyptus (2.7), indicating a different reactivity during chemical pretreatments. The xylan content in sugarcane bagasse and straw was much higher than that in eucalyptus, with a significantly lower degree of substitution for uronic acids and acetyl groups. The sugarcane straw showed the highest mass loss during the investigated pretreatments, especially under alkaline conditions, with a total biomass yield of only 37.3%. During the hydrothermal and dilute acid treatments, mostly hemicelluloses were removed, followed by the formation a significant amount of pseudo-lignin structures, while the alkaline pretreatment affected the lignin content. With eucalyptus, the formation of structures similar in their behavior to extractives (i.e., soluble in toluene and ethanol, subsequently referred to as "pseudo-extractives") was observed during all three pretreatments, with 12.4% for hydrothermal, 18.9% for dilute acid, and 8.7% for alkaline pretreatment. This information, combined with actual yields, should be taken into account when assessing the impact of pretreatments on the chemical composition and structure of biomass.

  • 25. Myglovets, M.
    et al.
    Poddubnaya, O. I.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lindström, Mikael E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gawdzik, B.
    Sobiesiak, M.
    Tsyba, M. M.
    Sapsay, V. I.
    Klymchuk, D. O.
    Puziy, A. M.
    Preparation of carbon adsorbents from lignosulfonate by phosphoric acid activation for the adsorption of metal ions2014In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 80, p. 771-783Article in journal (Refereed)
    Abstract [en]

    Activated carbons were prepared from sodium lignosulfonate by phosphoric acid activation at carbonization temperatures of 400-1000 degrees C. The resulting materials were characterized with regard to their surface area, pore volume, pore size distribution, distribution of surface groups and ability to adsorb copper ions. Activated carbons were characterized by nitrogen adsorption, scanning electron microscopy, Fourier transform infrared spectroscopy and thermal gravimetric analyses. The results indicate that with increasing carbonization temperature, the surface area decreased from 770 m(2)/g at 400 degrees C to 180 m(2)/g at 700 degrees C and increased at higher temperatures to 1370 m(2)/g at 1000 degrees C. The phosphorus content peaked at 11% for carbon obtained by carbonization at 800 degrees C. Potentiometric titration revealed the acidic character of all the phosphoric acid-activated carbons, which were found to have total concentrations of surface groups of up to 3.3 mmol/g. The carbons showed a high adsorption capacity for copper ions even at pH values as low as 2.

  • 26. Podkoscielna, Beata
    et al.
    Sobiesiak, Magdalena
    Zhao, Yadong
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gawdzik, Barbara
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Preparation of lignin-containing porous microspheres through the copolymerization of lignin acrylate derivatives with styrene and divinylbenzene2015In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 69, no 6, p. 769-776Article in journal (Refereed)
    Abstract [en]

    A novel method for synthesizing microspheres from lignin or lignin acrylate derivatives through copolymerization with styrene (St) and divinylbenzene (DVB) has been developed. The copolymers were obtained by the emulsion-suspension polymerization with a constant molar ratio of DVB to St of 1: 1 (w/w) and different amounts of lignin or its derivatives. The morphologies of the obtained materials were examined by scanning electron microscopy. Two types of lignin modifications were performed to introduce vinyl groups into the lignin molecules: modification with acrylic acid and modification with epichlorohydrin plus acrylic acid. The course of modification was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy. The thermal stability and degradation behavior of the obtained microspheres were investigated by thermogravimetric analysis, and the pore structure was characterized via nitrogen sorption experiments. Owing to the presence of specific functional groups and the well-developed pore structure, the obtained Lignin-St-DVB microspheres may have potential application as specific sorbents for the removal of phenolic pollutants from water, as demonstrated by the solid-phase extraction technique.

  • 27. Podkościelna, B.
    et al.
    Goliszek, M.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    New approach in the application of lignin for the synthesis of hybrid materials2017In: Pure and Applied Chemistry, ISSN 0033-4545, E-ISSN 1365-3075, Vol. 89, no 1, p. 161-171Article in journal (Refereed)
    Abstract [en]

    In this study, a novel method for the synthesis of hybrid, porous microspheres, including divinylbenzene (DVB), triethoxyvinylsilane (TEVS) and methacrylated lignin (L-Met), is presented. The methacrylic derivatives of kraft lignin were obtained by reaction with methacryloyl chloride according to a new experimental protocol. The course of the modification of lignin was confirmed by attenuated total reflectance (ATR-FTIR) and nuclear magnetic resonance (NMR) spectroscopy. The emulsion-suspension polymerization method was employed to obtain copolymers of DVD, TEVS and L-Met in spherical forms. The porous structures and morphologies of the obtained lignin-containing functionalized microspheres were investigated by low-temperature nitrogen adsorption data and scanning electron microscopy (SEM). The microspheres are demonstrated to be mesoporous materials with specific surface areas in the range of 430-520 m2/g. The effects of the lignin component on the porous structure, shape, swelling and thermal properties of the microspheres were evaluated.

  • 28. Podkościelna, B.
    et al.
    Gordobil, O.
    Riazanova, Anastasiia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Dobele, G.
    Labidi, J.
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Gun'ko, V. M.
    Sevastyanova, Olena
    Novel Porous Materials Obtained from Technical Lignins and Their Methacrylate Derivatives Copolymerized with Styrene and Divinylbenzene2017In: ChemistrySelect, ISSN 2365-6549, Vol. 2, no 7, p. 2257-2264Article in journal (Refereed)
    Abstract [en]

    The increasing availability of various types of technical lignins as result of the emergence of new biorefinery technologies has boosted the interest in the commercialization of lignin-based materials. Here we suggest a novel method for the preparation of uniform porous microspheres through emulsion-suspension polymerization of various technical lignins and related methacrylates with styrene (St) and divinylbenzene (DVB). Obtained microspheres have diameters in the range of 5–50 μm, with a more uniform shape for copolymers that contains lignin derivatives. Nitrogen sorption with DFT theory indicates that the microspheres are mesoporous materials with specific surface areas in the range of 230–270 m2g−1 but with significant differences in pore volume, especially in the mesopores size range (0–0.65 cm3g−1). Theoretical modeling of lignin alone and in St-DVB composites shows changes in polarity of the structures, which have become mosaics with hydrophilic and hydrophobic functionalities. This structure affects the properties of the interfacial water and, therefore, can affect the adsorption of both polar and nonpolar adsorbates in solid-phase extraction.

  • 29.
    Puziy, Alexander M.
    et al.
    NAS Ukraine, Inst Sorpt & Problems Endoecol, Naumov St 13, UA-03164 Kiev, Ukraine..
    Poddubnaya, Olga I.
    NAS Ukraine, Inst Sorpt & Problems Endoecol, Naumov St 13, UA-03164 Kiev, Ukraine..
    Sevastyanova, Olena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Carbon Materials from Technical Lignins: Recent Advances2018In: Topics in Current Chemistry, ISSN 2365-0869, Vol. 376, no 4, article id 33Article, review/survey (Refereed)
    Abstract [en]

    Lignin, a major component of lignocellulosic biomass, is generated in enormous amounts during the pulp production. It is also a major coproduct of second generation biofuels. The effective utilization of lignin is critical for the accelerated development of the advanced cellulosic biorefinery. Low cost and availability of lignin make it attractive precursor for preparation of a range of carbon materials, including activated carbons, activated carbon fibers (CF), structural CF, graphitic carbons or carbon black that could be used for environmental protection, as catalysts, in energy storage applications or as reinforcing components in advanced composite materials. Technical lignins are very diverse in terms of their molecular weight, structure, chemical reactivity, and chemical composition, which is a consequence of the different origin of the lignin and the various methods of lignin isolation. The inherent heterogeneity of lignin is the main obstacle to the preparation of high-performance CF. Although lignin-based CF still do not compete with polyacrylonitrile-derived CF in mechanical properties, they nevertheless provide new markets through high availability and low production costs. Alternatively, technical lignin could be used for production of carbon adsorbents, which have very high surface areas and pore volumes comparable to the best commercial activated carbons. These porous carbons are useful for purifying gas and aqueous media from organic pollutants or adsorption of heavy metal ions from aqueous solutions. They also could be used as catalysts or electrodes in electrochemical applications.

  • 30. Rabinovich, Mikhail L.
    et al.
    Fedoryak, Olesya
    Dobele, Galina
    Andersone, Anna
    Gawdzik, Barbara
    Lindstrom, Mikael E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Carbon adsorbents from industrial hydrolysis lignin: The USSR/Eastern European experience and its importance for modern biorefineries2016In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 57, p. 1008-1024Article, review/survey (Refereed)
    Abstract [en]

    This paper reviews the origin, distribution and composition of hydrolysis lignin, a large-scale by-product of the hydrolysis industry that operated in the Soviet Union and several eastern European countries from 1930s to the end of 1990s. The fundamental and industrial aspects of the production of various types of powdered and granular carbon adsorbents from hydrolysis lignin are considered through the prism of future large-scale production of biofuels and platform chemicals from renewable lignocellulosic resources. The advantages and drawbacks of hydrolysis lignin as a feedstock for the production of carbon adsorbents are compared with other types of feedstock, and the application of lignin-based carbons is discussed. 

  • 31.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    On the importance of oxidizable structures in bleached kraft pulps2005Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    After cooking, kraft pulps always contain not only residual lignin but also significant amounts of hexenuronic acid and other non-lignin structures oxidizable by permanganate under the standard kappa number determination conditions. These here referred to as false lignin. Like ordinary lignin, the false lignin also consumes bleaching chemicals, thus increasing both the production costs and the environmental impact of bleach plant effluents. The false lignin also has an effect on pulp properties such as brightness stability. This necessitates the development of efficient experimental routines for the determination of false lignin in different types of unbleached and bleached kraft pulps, together with studies of its formation, chemical behaviour, and ultimate fate.

    The main aim of this work has been to establish a method for the quantification of various types of oxidizable structures in bleached kraft pulps and to study their impact on pulp quality, particularly, on the brightness stability of pulps bleached in elemental-chlorine-free (ECF) and a totally-chlorine-free (TCF) processes.

    Part of this research deals with the relationship between the kappa number and the lignin content in the case of partly oxidized lignins. Spruce and birch kraft pulps processed according to the ODEQP and OQ(OP)Q(PO) bleaching sequences, respectively, have been analyzed. It has been found that the oxidation equivalent of the residual lignin decreases with increasing degree of oxidation along each bleaching sequence. This finding has been further supported by experiments with a number of model compounds. The Ox-Dem kappa number method has been shown to be an accurate means of determining the residual lignin content and of monitoring the efficiency of lignin removal along different bleaching sequences. It has been demonstrated that the kappa number can always be fractioned into partial contributions, the first of which comes from the residual lignin and is measured by the Ox-Dem kappa number, and the second from the false lignin and is given by the difference between the standard kappa number and the Ox-Dem kappa number. The effect of false lignin on the pulp kappa number is most pronounced in unbleached and oxygen-delignified kraft pulps. The extractability of residual and false lignin in different solvents has been investigated. The changes that occurred in the kappa number following different extraction steps have been compared with corresponding changes in the chemical composition and the conclusion has been drawn that the hemicellulose component of a kraft pulp is a major sourse of non-lignin structures contributing to the kappa number.

    The influence on the brightness stability of various oxidizable structures, viz.: residual lignin, hexenuronic acid and other non-lignin structures, in spruce, birch and eucalyptus kraft pulps bleached in ECF and TCF type processes was studied. It was demonstrated that the selective removal of all false lignin structures significantly improves the brightness stability. The degree of yellowing was found to be proportional to the content of HexA groups in pulps. It has been shown that 2-furancarboxylic acid, 5-formyl-2furancarboxylic acid and reductic acid are formed during the course of thermal yellowing. The influence of two bleaching sequences, D0(EP)D1 (ECF-type) and Q1(OP)Q2(PO) (TCF)-type, on the content of different oxidizable structures in eucalyptus kraft pulp was studied in relation to the brightness stability of the pulp. It was shown by kappa number fractionation that pulp bleached to full brightness with ECF- and TCF-type sequences contains different amounts of HexA. The most significant discoloration was observed in the case of TCF-bleached pulp having an especially high content of HexA.

    The mechanism of the moist (8 % moisture) thermal yellowing of fully bleached kraft pulps was further studied using dissolving pulp impregnated with a set of model compounds representing the most likely HexA degradation products, viz. as 2-furancarboxylic acid (FA), 5-formyl-2-furancarboxylic acid (FFA) and reductic acid (RA), either alone or in combination with Fe(II) or Fe(III) ions. It was found that the latter two acids take part in reactions leading to colour formation whereas 2-furancarboxylic acid does not. The effect of iron ions on the colour formation appears to vary with their oxidation state. The brightness loss caused by either FFA or RA, present in an amounts similar to the content of HexA in industrial pulps, was of the same order of magnitude as that observed in industrial pulps aged under the same conditions. Based on these findings, it is suggested that the overall mechanism of moist thermal yellowing involves several stages, including the degradation of hexenuronic acid and the formation of reactive precursors, such as 5-formyl-2-furancarboxylic acid and reductic acid. The presence of ferrous ions further enhances the discoloration.

  • 32.
    Sevastyanova, Olena B.
    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 L. F.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    On the reaction mechanism of thermal yellowing of chemical pulp2005In: Appita Annu. Conf., 2005, p. 517-523Conference paper (Refereed)
    Abstract [en]

    In the present research the mechanism of colour formation in the bleached kraft pulps was studied based on the accelerated ageing experiments with industrial bleached pulps and cellulose samples doped with a number of model compounds: 2-furancarboxylic acid (FA), 5-formyl-2-furancarboxylic acid (FFA) and reductic acid (RA) in combination with Fe2+ or Fe3+ ion. The choice of the model compounds was based on the fact that they were detected in the ethanol extracts of aged industrial pulps. It was shown that the mechanism of thermal yellowing consist of several stages, including the degradation of hexenuronic acid and formation of reactive precursors, such as FFA and RA, which then take part in reactions leading to colour formation. The formation of FFA and RA is the rate-limiting stage in the discoloration of pulps. FA had basically no influence on the yellowing. The effect of Fe ions on the colour formation appears to vary with their oxidation state. The presence of Fe2+ in combination of FFA, and especially, with RA has been shown to facilitate the colour formation, whereas Fe3+ seems to suppress the discoloration caused by the FFA or RA.

  • 33.
    Sevastyanova, Olena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Use of Ionic Liquids for the pretreatment of cellulose fibre materials for improved rectivity and value added applications2009Conference paper (Other academic)
  • 34.
    Sevastyanova, Olena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Forsström, A.
    Wackerberg, E.
    Lindström, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Bleaching of eucalyptus kraft pulps with chlorine dioxide: Factors affecting the efficiency of the final D stage2012In: TAPPI Journal, ISSN 0734-1415, Vol. 11, no 3, p. 43-53Article in journal (Refereed)
    Abstract [en]

    We investigated the bleaching efficiency of the final chlorine dioxide (D 2) stage in the D 0(EP)D 1D 2 bleaching sequence, focusing on the effect of pH in relation to the bleaching history of pulp samples. The samples used were unbleached kraft Eucalyptus grandis pulps with kappa no. 14.8 and the same pulp oxygen-delignified to kappa nos. 12 and 9.8. The samples were bleached according to the D 0(EP)D 1 sequence to a brightness of about 86% ISO and then submitted to the final D 2 stage under identical conditions (e.g., chlorine dioxide charge, time, temperature, and final pH). The target final brightness was 90.5% ISO. Changes in the kappa number, brightness, viscosity, and contents of hexenuronic acid, 4-O-methylglucuronic acid, and the total amount of carboxylic acid (COOH) groups in pulps were monitored during the bleaching sequence. The final brightness of eucalyptus kraft pulps increased when the terminal pH of the D 2 stage was raised from 3.0 to 6.5. The 90.5% ISO target brightness in the D 2 stage was achieved for all pulps within a pH range of 4.5-6.5, but this required adjusting final pH for individual samples. The optimal pH value with respect to pulp viscosity was between 3 and 5. Despite dissimilar conditions applied in previous bleaching stages, the samples after the D 1 stage revealed similar residual lignin contents as shown by kappa number analysis. The content of hexenuronic acid in the samples, however, varied broadly, from 2 to 26 mmol/kg. Conductometric titration showed different amounts of carboxylic acid groups in pulps after the D 1 stage, of which hexenuronic acid accounted for only a minor part. The variations in the fiber charge resulted from the different bleaching conditions applied before the D 2 stage. The fiber charge affected the alkali demand in the final D 2 stage, whereas variations in the alkali demand affected the initial pH and associated process kinetics. Lower total fiber charge was found to be beneficial for improved final brightening and viscosity when bleached at higher final pH. Application: This study will help pulp mill engineers to better understand how a pulp's oxidative history may affect the process kinetics in the final D bleaching stage. Fiber charge is important when selecting optimal pH for the final brightening of eucalyptus kraft pulps.

  • 35.
    Sevastyanova, Olena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Forsström, A.
    Wackerberg, E.
    Lindström, Mikael E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Bleaching of eucalyptus kraft pulps with chlorine dioxide: Factors affecting the efficiency of the final D stage2011In: Int. Pulp Bleach. Conf., IPBC, 2011, p. 376-403Conference paper (Refereed)
    Abstract [en]

    The bleaching efficiency of the final D stage in the D 0(EP) D 1D 2 bleaching sequence was investigated focusing on the effect of pH in relation to the bleaching history of pulp samples. The pulps used were unbleached kraft Eucalyptus grandis pulps with a kappa number of 14.8, and the same pulp oxygen-delignified to kappa numbers 12 and 9.8. The samples were bleached according to the D 0(EP)D 1 sequence to a brightness of about 86% ISO and then submitted to the final D 2 stage under identical conditions. The target final brightness was 90.5% ISO. Changes in the kappa number, brightness, viscosity and contents of hexenuronic acid (HexA), 4-O-methylglucuronic acid and the total amount of carboxylic acid groups in pulps were monitored during the bleaching sequence. The target brightness in the D 2 stage was achieved for all pulps, but this required a different final pH for individual samples, indicating dissimilarities between chromophore types in them. In general, brightness increased as the pH increased from 3 to 6. The optimal value with respect to pulp viscosity was between pH 3 and 5. Despite unlike conditions applied in previous bleaching stages, the samples after the D 1 stage revealed similar residual lignin contents as shown by kappa number analysis. The content of hexenuronic acid in the samples was, however, found to vary broadly in the range from 2 to 26 mmol/kg. Conductometric titration showed different amounts of carboxylic (COOH) groups in pulps after the D 1 stage, of which HexA accounted for only a minor part. Since the content of 4-O-methylglucuronic acid groups was similar for all samples, the difference in the amount of COOH groups was mainly associated with oxidation of the residual lignin. Some of the charges might also originate from oxidized cellulose. It was concluded that the variations in the fiber charge result from the different bleaching conditions applied prior to the D 1 stage.

  • 36.
    Sevastyanova, Olena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Forsström, Annbritt
    Eka Chemicals AB, Bohus.
    Wackerberg, Eva
    Eka Chemicals AB, Bohus.
    Lindström, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Impact of bleaching sequence on the efficiency of final chlorine dioxide stage in ECF-type bleaching of eucalyptus kraft pulps2011Conference paper (Other academic)
  • 37.
    Sevastyanova, Olena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Forsström, Annbritt
    Eka Chemicals AB, Bohus.
    Wackerberg, Eva
    Eka Chemicals AB, Bohus.
    Lindström, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    The final bleaching of eucalyptus kraft pulp with chlorine dioxide: what factors affecting its efficiency?2011Conference paper (Other academic)
  • 38.
    Sevastyanova, Olena
    et al.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Gellerstedt, Göran
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Li, Jiebing
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Extractability and chemical structure of residual and false lignin in kraft pulps2001Conference paper (Refereed)
  • 39.
    Sevastyanova, Olena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Helander, Mikaela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Chowdhury, Sudip
    Wedin, Helena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Kadla, John F.
    Lindström, Mikael E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Evaluation of physico-chemical properties and prediction of spinning parameters for high-quality lignins produced by ultra-filtration of industrial Kraft liquor2013In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 245Article in journal (Other academic)
  • 40.
    Sevastyanova, Olena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Dongfang
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Evaluation of Ionic Liquids as direct solvents for the manufacturing of novel products from cellulose2010Conference paper (Other academic)
  • 41.
    Sevastyanova, Olena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Li, Dongfang
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Evaluation of Ionic Liquids as direct solvents for the manufacturing of novel products from cellulose2010Conference paper (Refereed)
  • 42.
    Sevastyanova, Olena
    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.
    On the reaction mechanism of the thermal yellowing of bleached chemical pulps2006In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 21, no 2, p. 188-192Article in journal (Refereed)
    Abstract [en]

    The mechanism of moist thermal yellowing of fully bleached chemical pulps was studied using dissolving pulp impregnated with different types of degradation products from hexenuronic acid, viz. 2-furancarboxylic acid, 5-formyl-2-furancarboxylic acid and 2,3-dihydroxy-2-cyclopenten-l-one (reductic acid) either alone or in combination with Fe2+ or Fe3+ ions. It was found that the two latter acids take part in reactions leading to colour formation whereas 2-furancarboxylic acid does not. The effect of iron ions on the colour formation appears to depend on their oxidation state. The brightness loss caused by either 5-formyl-2-furancarboxylic acid or reductic acid, present in an amount similar to the content of hexenuronic acid in industrial pulps, was of the same order of magnitude as that observed for industrial pulps aged under the same conditions. Based on these findings, the overall mechanism of thermal yellowing is suggested to involve several stages, including the degradation of hexenuronic acid and the formation of reactive precursors, such as 5-formyl-2-furancarboxylic acid or reductic acid, which subsequently take part in the yellowing reactions. The presence of ferrous ions further enhances the discoloration.

  • 43.
    Sevastyanova, Olena
    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.
    The influence of various oxidizable structures on the brightness stability of the bleached chemical pulps2006In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 21, no 1, p. 49-53Article in journal (Refereed)
    Abstract [en]

    The influence on the brightness stability of various oxidizable structures viz.: lignin, hexenuronic acid and other "non-lignin" structures in kraft Pulps was studied. Samples of pulp of different wood species (spruce, birch, eucalyptus) taken from TCF and ECF bleaching sequences were chemically characterised by kappa number fractionation and subjected to accelerated ageing. It was shown that the selective removal of all oxidizable structures of carbohydrate origin present in the pulp significantly improved the brightness stability. The thermal yellowing of the pulps was found to be proportional to the content of hexenuronic acid groups regardless of the pulp origin or bleaching history. Quantitative determination of the changes during ageing showed that 2-furancarboxylic acid and 5-formyl-2-furancarboxylic acid are formed in the course of decomposition of hexenuronic acid. The difference between the original amount of hexenuronic acid groups in a pulp sample and the sum of the remaining hexenuronic acid together with the 2-furancarboxylic acid and 5-formyl-2-furancarboxylic acid suggests that the latter are involved in further reactions leading to the formation of chromophoric structures. It was also found that 2,3-dihydroxy-2-cyclopenten-1-one (reductic acid) is formed during the ageing.

  • 44.
    Sevastyanova, Olena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lindström, Mikael E.
    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.
    The influence of a bleaching sequence on the brightness stability of eucalyptus kraft pulp2005In: Appita Annual Conference, 2005, p. 251-255Conference paper (Refereed)
    Abstract [en]

    In the present research the influence of two bleaching sequences, D 0(EP)D1 (ECF-type) and Q1(OP)Q2(PO) (TCP-type), on the content of different oxidizable structures and metal ions in eucalyptus kraft pulp was studied in relation to the brightness stability of the pulp. It was shown that pulps bleached to full brightness with ECF- and TCF-type sequences contain differing amounts of oxidizable structures of carbohydrate origin, such as hexenuronic acid (HexA). These structures play a dominant role in the thermal yellowing of bleached kraft pulps and largely determine the yellowing kinetics. The most significant discoloration is observed for TCF-bleached pulps having an especially high content of HexA. The discoloration does not appear to be related to the presence of metal ions in pulps. There is a correlation between the HexA content and brightness stability of the bleached pulps. This correlation is due to reactions where HexA acts as a precursor in the formation of coloured compounds or intermediates which are then involved in the color formation. Furoic structures representing the main acid degradation products of HexA are suggested as the actual intermediates that cause yellowing by forming colored compounds.

  • 45.
    Sevastyanova, Olena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lindström, Mikael
    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.
    Influence of the bleaching sequence on the brightness stability of eucalyptus kraft pulp2007Conference paper (Other academic)
  • 46.
    Sevastyanova, Olena
    et al.
    UBC, Canada.
    Qin, Wei
    UBC, Canada.
    Kadla, John
    UBC, Canada.
    Effect of nanofillers as reinforcement agents for lignin composite fibers2010In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 117, no 5, p. 2877-2881Article in journal (Refereed)
    Abstract [en]

    Biobased nanocomposites and composite fibers were prepared from organosolv lignin/organoclay mixtures by mechanical mixing and subsequent melt intercalation. Two organically-modified montmorillonite (MMT) clays with different ammonium cations were used. The effect of organoclay varying from 1 to 10 wt % on the mechanical and thermal properties of the nanocomposites was studied. Thermal analysis revealed an increased in Tg for the nanocomposites as compared with the original organosolv lignin. For both organoclays, lignin intercalation into the silicate layers was observed using X-ray diffraction (XRD). The intercalated hybrids exhibited a substantial increase in tensile strength and melt processability. In the case of organoclay Cloisite 30B, X-ray analysis indicates the possibility of complete exfoliation at 1 wt % organoclay loading.

  • 47.
    Sevasyanova, Olena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Helander, Mikaela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Chowdhury, Sudip
    Lange, Heiko
    Wedin, Helena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Zhang, Liming
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Kadla, John F.
    Crestini, Claudia
    Lindström, Mikael F.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Tailoring the Molecular and Thermo-Mechanical Properties of Kraft Lignin by Ultrafiltration2014In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 131, no 18, p. 9505-9515Article in journal (Refereed)
    Abstract [en]

    This study has shown that ultrafiltration allows the selective extraction from industrial black liquors of lignin fraction with specific thermo-mechanical properties, which can be matched to the intended end uses. Ultrafiltration resulted in the efficient fractionation of kraft lignin according to its molecular weight, with an accumulation of sulfur-containing compounds in the low-molecular weight fractions. The obtained lignin samples had a varying quantities of functional groups, which correlated with their molecular weight with decreased molecular size, the lignin fractions had a higher amount of phenolic hydroxyl groups and fewer aliphatic hydroxyl groups. Depending on the molecular weight, glass-transition temperatures (T-g) between 70 and 170 degrees C were obtained for lignin samples isolated from the same batch of black liquor, a tendency confirmed by two independent methods, DSC, and dynamic rheology (DMA). The Fox-Flory equation adequately described the relationship between the number average molecular masses (M-n) and T-g's-irrespective of the method applied. DMA showed that low-molecular-weight lignin exhibits a good flow behavior as well as high-temperature crosslinking capability. Unfractionated and high molecular weight lignin (M-w > 5 kDa), on the other hand, do not soften sufficiently and may require additional modifications for use in thermal processings where melt-flow is required as the first step.

  • 48. Sobiesiak, Magdalena
    et al.
    Podkoscielna, Beata
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Thermal degradation behavior of lignin-modified porous styrene-divinylbenzene and styrene-bisphenol A glycerolate diacrylate copolymer microspheres2017In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 123, p. 364-375Article in journal (Refereed)
    Abstract [en]

    This paper describes the thermal properties of polymeric porous microspheres that contain a natural wood-derived polymer, lignin, as one of the components. Polymeric microspheres were obtained by the reaction of divinylbenzene (DVB) or bisphenol A glycerolate diacrylate (BPA.DA) with styrene (St) and a lignin component. The lignin components were unmodified lignin (L), lignin esterified with acrylic acid (LA) or lignin initially reacted with epichlorohydrin and then with acrylic acid (LEA). The copolymers were obtained by emulsion-suspension polymerization at a constant mole ratio of the tetrafunctional monomer DVB or BPA.DA to styrene St (1:1 w/w) and different types of lignin components. The thermal stabilities and degradation behavior of the obtained microspheres were studied by a thermogravimetric (TG/DTG/DSC) analysis. The evolved gases were analyzed by FTIR spectrometry. The influence of the lignin component on thermal properties of the obtained polymeric microspheres is evaluated and discussed. Due to the presence of the specific functional groups and well-developed porous structure, the obtained lignin-containing microspheres have a potential application as specific sorbents. Based on the high char content during the pyrolysis, the copolymers containing the lignin additives can be also considered as potential precursors for preparation of carbon materials.

  • 49.
    Svärd, Antonia
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Dobele, Galina
    Jurkjane, Vilhemina
    Brännvall, Elisabet
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    COST Action FP1105: effect of raw materials and pulping conditions on the characteristics of dissolved kraft lignins2016In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, no 12, p. 1105-1114Article in journal (Refereed)
    Abstract [en]

    The composition, molecular weight (MW), and chemical structure of technical lignins as byproducts of pulping influence their application in terms of physical and chemical properties, reactivity, and performance. It is important to know how the analytical data of technical lignins are influenced by the wood species and the parameters of pulping. The present study focuses on kraft pulping and how the wood species (eucalyptus, pine, and spruce) and variable cooking times influence the characteristics of dissolved lignins. The black liquor (BL) was recovered after three different cooking times and the precipitated lignin was characterized by total acid hydrolysis including the determination of the acid insoluble part (Klason lignin, KL) and the sugars in the hydrolysate, elemental analysis, 31P NMR spectroscopy, analytical pyrolysis (Py-GC/MS), gel permeation chromatography (GPC), thermogravimetry (TG), and differential scanning calorimetry (DSC). The results indicate that the phenolic OH content, MW and glass transition temperature increased with longer cooking times for the softwood (SW) lignins. These lignins had also a higher MW (M-w 5500-8000 g mol(-1)), than the eucalyptus lignin (M-w 2200-2400 g mol(-1)). Eucalyptus lignin had higher sulfur content compared to SW.

  • 50.
    Tagami, Ayumu
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Gioia, Claudio
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Lauberts, Maris
    Latvian State Inst Wood Chem, 27 Dzerbenes Str, LV-1006 Riga, Latvia..
    Budnyak, Tetyana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Moriana, Rosana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Sevastyanova, Olena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Solvent fractionation of softwood and hardwood kraft lignins for more efficient uses: Compositional, structural, thermal, antioxidant and adsorption properties2019In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 129, p. 123-134Article in journal (Refereed)
    Abstract [en]

    This work summarizes the impact of solvent fractionation on the chemical structure, antioxidant activity, heating values, and thermal and adsorption properties of industrial hardwood and softwood kraft lignins. The aim of the research was to develop a simple approach for obtaining lignin fractions with tailored properties for applications in certain materials. Four common industrial solvents, namely, ethyl acetate, ethanol, methanol and acetone, in various combinations, were found to be efficient for separating spruce and eucalyptus kraft lignins into fractions with low polydispersities. The ethanol fraction of spruce and the ethyl acetate fraction of eucalyptus afforded the highest yields. Gel-permeation chromatography analysis was used to evaluate the efficiency of the chosen solvent combination for lignin fractionation. The composition and structure of the lignin material was characterized by elemental analysis, analytical pyrolysis (Py-GC/MS/FID) and P-31 NMR spectro-scopy. The thermal properties of the lignin samples were studied using thermogravimetric analysis. Proximate analysis data (ash, volatile components, organic matter and fixed carbon) was obtained through the direct measurement of weight changes in each experimental curve, and the high heating values (in MJ/kg) were calculated according to equations suggested in the literature. The adsorption properties of fractionated kraft lignins were studied using methylene blue dye. The correlations observed between molecular weight, composition and functionality and the thermal, radical scavenging and adsorption properties of the lignin fractions provides useful information for selecting the appropriate solvent combinations for specific applications of lignin raw materials (including their use as antioxidants, biofuels or sorbents in water treatment processes).

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