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  • 1. Abdel-Rehim, M.
    et al.
    Altun, Zeki
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    New trend in sample preparation: On-line microextraction in packed syringe (MEPS) for LC and GC applications, Part II, Determination of ropivacaine and its metabolites in human plasma samples using MEPS-LC-MS-MS2004In: J. Mass Spectr., 39 (2004) 1488-1493Article in journal (Refereed)
  • 2. Abdel-Rehim, M.
    et al.
    Carlsson, Gunilla
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad University, Faculty of Technology and Science, Materials Science.
    Bielenstein, M.
    Arvidsson, T.
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Evaluation of Solid-Phase microextraction (SPME) for Study of the protein Binding in Human Plasma Samples,2000In: J. Chromatogr. Sci., 38 (2000) 458-464Article in journal (Refereed)
  • 3. Abdel-Rehim, M.
    et al.
    Hassan, Z.
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Hassan, M.
    Determination of Busulphan in plasma samples by gas chromatography-mass spectrometry (GC-MS) using on-line derivatization utilizing solid-phase microextraction (SPME)2003In: J. Therapeutic Drug Monitoring, 25 (2003) 400-406Article in journal (Refereed)
  • 4. Abdel-Rehim, M.
    et al.
    Skansen, P.
    Vita, M.
    Hassan, Z.
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Hassan, M.
    Microextraction in packed syringe / liquid chromatography /electrospray tandem mass spectrometry (MEPS/LC/MS/MS) for quantification of olomoucine in human plasma samples2005In: Anal.Chim. Acta., 539 (2005) 35-39Article in journal (Refereed)
  • 5.
    Abdel-Rehim, Mohamed
    et al.
    AstraZeneca R&D Södertälje, Södertälje, Sweden.
    Andersson, L.I.
    AstraZeneca R&D Södertälje, Södertälje, Sweden.
    Altun, Zeki
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Microextraction in Packed Syringe Online with Liquid Chromatography-Tandem Mass Spectrometry: Molecularly imprinted polymer as packing material for MEPS in selective extraction of ropivacaine from plasma2006In: Journal of Liquid Chromatography & Related Technologies, ISSN 1082-6076, E-ISSN 1520-572X, Vol. 29, no 12, p. 1725-1736Article in journal (Refereed)
    Abstract [en]

    The excellent performance of a new sample preparation method, microextraction in packed syringe (MEPS), was recently illustrated by online LC‐MS and GS‐MS assays of local anaesthetics in plasma samples. In the method, approximately 1 mg of solid packing material was inserted into a syringe (100–250 µL) as a plug. Sample preparation took place on the packed bed. The new method was easy to use, fully automated, of low cost, and rapid in comparison with previously used methods. This paper presents the use of molecularly imprinted polymers (MIPs) as packing material for higher extraction selectivity. Development and validation of a method for MIP‐MEPS online with LC‐MS‐MS using ropivacaine in plasma as model compound were investigated. A bupivacaine imprinted polymer was used. The method was validated and the standard curves were evaluated by means of quadratic regression and weighted by inverse of the concentration: 1/x for the calibration range 2–2000 nM. The applied polymer could be used more than 100 times before the syringe was discarded. The extraction recovery was 60%. The results showed high correlation coefficients (R 2 >0.999) for all runs. The accuracy, given as a percentage deviation from the nominal concentration values, ranged from -6% to 3%. The precision, given as the relative standard deviation, at three different concentrations (QC samples) was consistently about 3% to 10%. The limit of quantification was 2 nM.

  • 6. Abdel-Rehim, Mohamed
    et al.
    Dahlgren, Marie
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Quantification of ropivacaine and its major metabolites in human urine samples utilizing microextraction in packed syringe automated with liquid chromatography-tandem mass spectrometry (MEPS-LC-MS-MS)2006In: J. Sep. Sci., 29 (2006) 1658-1661Article in journal (Refereed)
  • 7. Abdel-Rehim, Mohamed
    et al.
    Dahlgren, Marie
    Claude, Saturnin
    Tabacchi, Raphael
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Microextraction in packed syringe (MEPS) utilizing methylcyanopropyl silarylene as coating polymer for extraction of drugs in biological samples,2006In: J. Liq. Chromatogr. & Relat. Technol., 29 (2006) No. 17, 2537-2544Article in journal (Refereed)
  • 8.
    Acker, Pascal
    et al.
    University of Freiburg, Germany.
    Rzesny, Luisa
    University of Freiburg, Germany.
    Marchiori, Cleber F. N.
    Uppsala universitet.
    Araujo, Carlos Moyses
    Uppsala universitet.
    Esser, Birgit
    University of Freiburg, Germany.
    π-Conjugation Enables Ultra-High Rate Capabilities and Cycling Stabilities in Phenothiazine Copolymers as Cathode-Active Battery Materials2019In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 29, no 45, article id 1906436Article in journal (Refereed)
    Abstract [en]

    In recent years, organic battery cathode materials have emerged as an attractive alternative to metal oxide–based cathodes. Organic redox polymers that can be reversibly oxidized are particularly promising. A drawback, however, often is their limited cycling stability and rate performance in a high voltage range of more than 3.4 V versus Li/Li+. Herein, a conjugated copolymer design with phenothiazine as a redox‐active group and a bithiophene co‐monomer is presented, enabling ultra‐high rate capability and cycling stability. After 30 000 cycles at a 100C rate, >97% of the initial capacity is retained. The composite electrodes feature defined discharge potentials at 3.6 V versus Li/Li+ due to the presence of separated phenothiazine redox centers. The semiconducting nature of the polymer allows for fast charge transport in the composite electrode at a high mass loading of 60 wt%. A comparison with three structurally related polymers demonstrates that changing the size, amount, or nature of the side groups leads to a reduced cell performance. This conjugated copolymer design can be used in the development of advanced redox polymers for batteries.

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  • 9.
    Aderne, Rian E.
    et al.
    Pontifícia Universidade Católica do Rio de Janeiro – PUC-Rio, BRA.
    Borges, Bruno Gabriel A. L.
    Universidade Federal do Rio de Janeiro-UFRJ, BRA.
    Avila, Harold C.
    University of Atlantic, COL.
    von Kieseritzky, Fredrik
    Karolinska Institutet.
    Hellberg, Jonas
    Chemtron AB, Sweden.
    Koehler, Marlus
    Universidade Federal do Paraná-UFPR, BRA.
    Cremona, Marco
    Pontifícia Universidade Católica do Rio de Janeiro – PUC-Rio, BRA.
    Roman, Lucimara S.
    Universidade Federal do Paraná-UFPR, BRA.
    Araujo, Moyses C.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013). Uppsala University.
    Rocco, Maria Luiza M.
    Universidade Federal do Rio de Janeiro-UFRJ, BRA.
    Marchiori, Cleber
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    On the energy gap determination of organic optoelectronic materials: the case of porphyrin derivatives2022In: Materials Advances, E-ISSN 2633-5409, no 3, p. 1791-1803Article in journal (Refereed)
    Abstract [en]

    The correct determination of the ionization potential (IP) and electron affinity (EA) as well as the energy gap is essential to properly characterize a series of key phenomena related to the applications of organic semiconductors. For example, energy offsets play an essential role in charge separation in organic photovoltaics. Yet there has been a lot of confusion involving the real physical meaning behind those quantities. Experimentally the energy gap can be measured by direct techniques such as UV-Vis absorption, or indirect techniques such as cyclic voltammetry (CV). Another spectroscopic method is the Reflection Electron Energy Loss Spectroscopy (REELS). Regarding data correlation, there is little consensus on how the REELS' energy gap can be interpreted in light of the energies obtained from other methodologies such as CV, UV-Vis, or photoemission. In addition, even data acquired using those traditional techniques has been misinterpreted or applied to derive conclusions beyond the limits imposed by the physics of the measurement. A similar situation also happens when different theoretical approaches are used to assess the energy gap or employed to explain outcomes from experiments. By using a set of porphyrin derivatives as model molecules, we discuss some key aspects of those important issues. The peculiar properties of these porphyrins demonstrate that even straightforward measurements or calculations performed in a group of very similar molecules need a careful interpretation of the outcomes. Differences up to 660 meV (similar to 190 meV) are found comparing REELS (electrochemical) measurements with UV-Vis energy gaps, for instance. From the theoretical point of view, a reasonable agreement with electrochemical measurements of the IP, EA, and the gap of the porphyrins is only obtained when the calculations involve the full thermodynamics of the redox processes. The purpose of this work is to shed light on the differences and similarities of those aforementioned characterization methods and provide some insight that might help one to develop a critical analysis of the different experimental and theoretical methodologies.

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  • 10.
    Ahmad, Tausif
    et al.
    Universiti Teknologi PETRONAS, MYS.
    Bustam, Mohamad Azmi
    Universiti Teknologi PETRONAS, MYS.
    Zulfiqar, Muhammad
    Universiti Teknologi PETRONAS, MYS.
    Moniruzzaman, Muhammad
    Universiti Teknologi PETRONAS, MYS.
    Idris, Alamin
    Universiti Teknologi PETRONAS, MYS.
    Iqbal, Jibran
    Zayed University, ARE.
    Asghar, Hafiz Muhammad Anwaar
    University of the Punjab, PAK.
    Ullah, Sami
    King Khalid University, SAU.
    Controllable phytosynthesis of gold nanoparticles and investigation of their size and morphology-dependent photocatalytic activity under visible light2020In: Journal of Photochemistry and Photobiology A: Chemistry, ISSN 1010-6030, E-ISSN 1873-2666, Vol. 392, p. 1-11, article id 112429Article in journal (Refereed)
    Abstract [en]

    Plants mediated synthesis of gold nanoparticles (AuNPs) containing desired characteristics for their suitable potential applications has been a challenging task, which is causing a major hindrance towards its commercialization. Therefore, herein phytosynthesis of AuNPs with required size and morphology has been achieved through manipulating the reaction conditions including reaction temperature and volume of Elaeis guineensis leaves (EGL) extract. Furthermore, photocatalytic potential of EGL mediated AuNPs having different size and shape has also been explored for the removal of methylene blue (MB) under visible light irradiation. The reaction temperature and volume of EGL strongly influenced the size and morphology of AuNPs, which are directly associated with the photocatalytic activities. The experimental results revealed that predominantly spherical and ultra-smaller size AuNPs with particle size of 16.26 ± 5.84 nm, formed at 70 °C showed the highest removal efficiency up to 92.55 % in 60 min. This highest photocatalytic activity of AuNPs could be attributed to the availability of higher number of low-coordinated gold (Au) atoms in the MB aqueous solution, which might have boosted the adsorption of the MB on the surface of particles and accelerated the degradation phenomenon. The proposed photocatalytic degradation mechanism of AuNPs for MB was also explained. The highly photoactive EGL mediated AuNPs with controllable morphology and size could be an advance step in future in chemical and biomedical applications.

  • 11. Almgren, M
    et al.
    Alsins, J
    Mukhtar, E
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad University, Faculty of Technology and Science, Materials Science.
    Diffusion-Controlled Fluorescence Quenching in Micelles1989In: Reactions in Compartmentalized Liquids; Knoche W and Shomacker R (eds), Springer-Verlag, Berlin Heidelberg (1989), 61-68, 1989Chapter in book (Refereed)
  • 12. Almgren, M.
    et al.
    Alsins, J.
    Mukhtar, E.
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad University, Faculty of Technology and Science, Materials Science.
    Fluorescence Quenching Dynamics in Rodlike Micelles1988In: J. Phys. Chem., 1988, 92, 4479-4483Article in journal (Refereed)
  • 13. Almgren, M.
    et al.
    Alsins, J.
    van Stam, Jan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Fluorescence Decay Studies of Structures and Dynamics in Ionic Micellar Solutions1988In: Ordering and Organization in Ionic Solutions, World Scientific, Singapore: World Scientific, 1988, p. 225-232Chapter in book (Refereed)
  • 14. Almgren, M
    et al.
    Alsins, J
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad University, Faculty of Technology and Science, Materials Science.
    Mukhtar, E
    The micellar sphere-to-rod transition in CTAC-NaClO3. A fluorescence quenching study1988In: Progr. Colloid Polym. Sci., 1988, 76, 68-74Article in journal (Refereed)
  • 15. Almgren, M.
    et al.
    Hansson, P.
    Mukhtar, E.
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad University, Faculty of Technology and Science, Materials Science.
    Aggregation of Alkyltrimethylammonium Surfactants in Aqueous Poly(styrenesulfonate) Solutions1992In: Langmuir, 1992, 8, 2405-2412Article in journal (Refereed)
  • 16. Almgren, M.
    et al.
    Löfroth, J-E
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad University, Faculty of Technology and Science, Materials Science.
    Fluorescence Decay Kinetics in Monodisperse Confinements with Exchange of Probes and Quenchers1986In: J. Phys. Chem., 1986, 90, 4431-4437Article in journal (Refereed)
  • 17. Almgren, M.
    et al.
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad University, Faculty of Technology and Science, Materials Science.
    Lindblad, C.
    Li, P.
    Stilbs, P.
    Bahadur, P.
    Aggregation of Poly(ethyelene oxide)-Poly(propylene oxide)-Poly(ethylene oxide) Triblock Copolymers in the Presence of Sodium Dodecyl Sulfate in Aqueous Solution1991In: J. Phys. Chem., 1991, 95, 5677-5684Article in journal (Refereed)
  • 18. Almgren, M
    et al.
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad University, Faculty of Technology and Science, Materials Science.
    Swarup, S
    Löfroth, J-E
    Structure and Transport in the Microemulsion Phase of the System Triton X-100-Toluene-Water1986In: Langmuir, 1986, 2, 432-438Article in journal (Refereed)
  • 19.
    Alriksson, Björn
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Ethanol from lignocellulose: Alkali detoxification of dilute-acid spruce hydrolysates2006Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Detoxification of dilute-acid lignocellulose hydrolysates by treatment with Ca(OH)2 (overliming) efficiently improves the production of fuel ethanol, but is associated with drawbacks like sugar degradation and CaSO4 precipitation. In factorial designed experiments, in which pH and temperature were varied, dilute-acid spruce hydrolysates were treated with Ca(OH)2, NH4OH or NaOH. The concentrations of sugars and inhibitory compounds were measured before and after the treatments. The fermentability was examined using the yeast Saccharomyces cerevisiae and compared with reference fermentations of synthetic medium without inhibitors. The treatment conditions were evaluated by comparing the balanced ethanol yield, which takes both the degradation of sugars and the ethanol production into account. Treatment conditions resulting in excellent fermentability and minimal sugar degradation were possible to find regardless of whether Ca(OH)2, NH4OH or NaOH was used. Balanced ethanol yields higher than those of the reference fermentations were achieved for hydrolysates treated with all three types of alkali. As expected, treatment with Ca(OH)2 gave rise to precipitated CaSO4. The NH4OH treatments gave rise to a brownish precipitate but the amounts of precipitate formed were relatively small. No precipitate was observed in treatments with NaOH. The possibility that the ammonium ions from the NH4OH treatments gave a positive effect as an extra source of nitrogen during the fermentations was excluded after experiments in which NH4Cl was added to the medium. The findings presented can be used to improve the effectiveness of alkali detoxification of lignocellulose hydrolysates and to minimize problems with sugar degradation and formation of precipitates.

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  • 20.
    Alriksson, Björn
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Ethanol from lignocellulose: Management of by-products of hydrolysis2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fuel ethanol can be produced from lignocellulosic materials, such as residues from agriculture and forestry. The polysaccharides of lignocellulose are converted to sugars by hydrolysis and the sugars can then be fermented to ethanol using microorganisms. However, during hydrolysis a wide range of by-products are also generated. By-product formation can affect ethanol yield and productivity. Management of by-products of hydrolysis is therefore important in the development of commercially viable production of cellulosic ethanol.

    Detoxification of inhibitory dilute-acid lignocellulose hydrolysates by treatment with Ca(OH)2 (overliming) efficiently improves the fermentability, but is associated with drawbacks like sugar degradation and CaSO4 precipitation. In factorial designed experiments, in which pH and temperature were varied, dilute-acid spruce hydrolysates were treated with Ca(OH)2, NH4OH or NaOH. The concentrations of sugars and inhibitory compounds were measured before and after the treatments. The fermentability was examined using the yeast Saccharomyces cerevisiae and compared with reference fermentations of synthetic medium without inhibitors. The treatment conditions were evaluated by comparing the balanced ethanol yield, which takes both the degradation of sugars and the ethanol production into account. Treatment conditions resulting in excellent fermentability and minimal sugar degradation were possible to find regardless of whether Ca(OH)2, NH4OH or NaOH was used. Balanced ethanol yields higher than those of the reference fermentations were achieved for hydrolysates treated with all three types of alkali. As expected, treatment with Ca(OH)2 gave rise to precipitated CaSO4. The NH4OH treatments gave rise to a brownish precipitate but the amounts of precipitate formed were relatively small. No precipitate was observed in treatments with NaOH. The findings presented can be used to improve the effectiveness of alkali detoxification of lignocellulose hydrolysates and to minimize problems with sugar degradation and formation of precipitates.

    Overexpression of different S. cerevisiae genes was investigated with the aim to engineer a biocatalyst with increased inhibitor tolerance. Overexpression of YAP1, a gene encoding a transcription factor, conveyed increased resistance to lignocellulose-derived inhibitors as well as to a dilute-acid hydrolysate of spruce.

    Recombinant Aspergillus niger expressing the Hypocrea jecorina endoglucanase Cel7B was cultivated on spent lignocellulose hydrolysate (stillage). The fungus simultaneously removed inhibitors present in the stillage and produced higher amounts of endoglucanase than when it was grown in a standard medium with comparable monosaccharide content. The concept can be applied for on-site production of enzymes in a cellulose-to-ethanol process and facilitate recycling of the stillage stream.

  • 21.
    Alriksson, Björn
    et al.
    Karlstad University, Division for Chemistry.
    Horváth, Ilona Sárvári
    Karlstad University, Division for Chemistry.
    Sjöde, Anders
    Karlstad University, Division for Chemistry.
    Nilvebrant, Nils-Olof
    Karlstad University, Division for Chemistry.
    Jönsson, Leif J
    Karlstad University, Division for Chemistry.
    Ammonium hydroxide detoxification of spruce acid hydrolysates.2005In: Applied Biochemistry and Biotechnology, ISSN 0273-2289, E-ISSN 1559-0291, Vol. 121-124, p. 911-22Article in journal (Refereed)
    Abstract [en]

    When dilute-acid hydrolysates from spruce are fermented to produce ethanol, detoxification is required to make the hydrolysates fermentable at reasonable rates. Treatment with alkali, usually by overliming, is one of the most efficient approaches. Several nutrients, such as ammonium and phosphate, are added to the hydrolysates prior to fermentation. We investigated the use of NH4OH for simultaneous detoxification and addition of nitrogen source. Treatment with NH4OH compared favorably with Ca(OH)2, Mg(OH)2, Ba(OH)2, and NaOH to improve fermentability using Saccharomyces cerevisiae. Analysis of monosaccharides, furan aldehydes, phenols, and aliphatic acids was performed after the different treatments. The NH4OH treatments, performed at pH 10.0, resulted in a substantial decrease in the concentrations of furfural and hydroxymethylfurfural. Under the conditions studied, NH4OH treatments gave better results than Ca(OH)2 treatments. The addition of an extra nitrogen source in the form of NH4Cl at pH 5.5 did not result in any improvement in fermentability that was comparable to NH4OH treatments at alkaline conditions. The addition of CaCl2 or NH4Cl at pH 5.5 after treatment with NH4OH or Ca(OH)2 resulted in poorer fermentability, and the negative effects were attributed to salt stress. The results strongly suggest that the highly positive effects of NH4OH treatments are owing to chemical conversions rather than stimulation of the yeast cells by ammonium ions during the fermentation.

  • 22.
    Alriksson, Björn
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Rose, Shaunita, H
    Department of Microbiology, University of Stellenbosch, South Africa.
    van Zyl, Wilhelm, H
    Department of Microbiology, University of Stellenbosch, South Africa.
    Sjöde, Anders
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Nilvebrant, Nils-Olof
    STFI-Packforsk AB, Stockholm, Sweden.
    Jönsson, Leif J.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Cellulase Production from Spent Lignocellulose Hydrolysates with Recombinant Aspergillus niger.2009In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 75, no 8, p. 2366-2374Article in journal (Refereed)
  • 23.
    Alriksson, Björn
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Sárvári Horváth, Ilona
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Jönsson, Leif J.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Overexpression of Saccharomyces cerevisiae transcription factor and multidrug resistance genes conveys enhanced resistance to lignocellulose-derived fermentation inhibitors.2010In: Process Biochemistry, ISSN 1359-5113, E-ISSN 1873-3298, Vol. 45, no 2, p. 264-271Article in journal (Refereed)
  • 24.
    Alshogran, Forat
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    Fabrication of battery separator by coating with sulfonated cellulose nanofibrils on kraft paper and inkjet paper substrates: Tillverkning av batteriseparator genom bestrykning med sulfonerad cellulosananofibriller på kraft papper och bläckstråle papper substrat2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Modified nanocellulose have distinctive qualities and have drawn a lot of interest from a variety of fields. It is a natural, sustainable product that is manufactured from plant-based materials like wood and other renewable resources. It is also biodegradable. It is a possible material for battery separators because of its great mechanical strength, flexibility, and ability to create a stable and consistent membrane. Due to the cost of using it as a membrane, it has been investigated in this work to see if it can be coated onto a substrate and used as battery separator. In this work sulfonated cellulose nanofibrils (SCNF) has been used to be coated on kraft paper and inkjet paper using a rod coater. Parameters like concentration, thickness and substrates have been varied in this experiment. Viscosity was measured using Brookfield instrument to measure the viscosity for 0,5% SCNF and 1,5% SCNF. The coating was carried out using a rod coater and varying between two rods to influence the thickness, the coating used concentrations of 0,5% SCNF and 1,5% SCNF and two different substrates, kraft paper and inkjet paper. Thickness was determined to study the effect of the variation in rod. The mechanical strength was tested on the coated paper substrates and compared the results to the noncoated substrates as reference, the mechanical strength showed an improvement with the coated SCNF substrates. Permeance through the Gurley method was studied in order to understand how the coated substrates behaves compared to the noncoated. Contact angle was determined as well to understand the wettability of the coated substrates and how they would behave as separators in zinc ion batteries. The contact angle decreased with increasing concentration of the SCNF which is a result of the sulfonate groups. Cross sections were analyzed using SEM to study the influence of the coating to the substrates. Ionic conductivity was also tested to evaluate the possibility of the coated substrates as separators.

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  • 25.
    Alshogran, Forat
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Mikroskopisk analys av polyvinylalkohol filmer samt defekternas inverkan på syrepermeabilitet2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In food packaging, it is very important that the material with which the food is packed acts as a good barrier to keep away for example oxygen so that the food lasts a longer time. Oxygen is kept away from the food because oxygen encourages the growth of microorganisms, resulting in mold and yeast growth therefor a good oxygen barrier is preferred.

    In this study polyvinyl alcohol (PVOH) films were produced with the concentrations of 10%, 15% and 20% PVOH. Controlled defects were also introduced to investigate the impact on oxygen barrier capacity, using optical microscopy oxygen transmission rate (OTR) measurement. A total of 3 tests were made on each concentration for both non-defect and defect equipped films.  

    In this study a permeometer is used to calculate the OTR value. The permeometer is supposed to measure the dynamic of the gas transmission with the three regions penetration, transient and stationary. In the manufacture of the PVOH films the concentration, thickness, and size of the defects of the films were checked. The viscosity was also checked but before the mixture of PVOH and water hardened. 

    For the defective PVOH films they let through more than the non-defective ones but for the PVOH concentration of 20% they let through the same amount regardless of it had defects or not. Microscopic analysis of defects showed a tendency for the bubble defects to look different where some bubble defects could be interconnected or have small bubble defects in themselves.

  • 26. Altun, Z.
    et al.
    Andersson, L.I.
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Abdel-Rehim, M.
    Some factors affecting the performance of microextraction in packed syringe (MEPS)2008In: submitted to Analyt. Chim. ActaArticle in journal (Refereed)
  • 27.
    Altun, Zeki
    Karlstad University, Division for Chemistry.
    New Techniques for Sample Preparation in Analytical Chemistry2005Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Sample preparation is often a bottleneck in systems for chemical analysis. The aim of this work was to investigate and develop new techniques to address some of the shortcomings of current sample preparation methods. The goal has been to provide full automation, on-line coupling to detection systems, short sample preparation times and high-throughput.

    A new technique for sample preparation that can be connected on-line to liquid chromatography (LC) and gas chromatography (GC) has been developed. Microextraction in packed syringe (MEPS) is a new solid-phase extraction (SPE) technique that is miniaturized and can be fully automated. In MEPS approximately 1 mg of sorbent material is inserted into a gas tight syringe (100-250 μL) as a plug. Sample preparation takes place on the packed bed. Evaluation of the technique was done by the determination of local anaesthetics in human plasma samples using MEPS on-line with LC and tandem mass spectrometry (MS-MS). MEPS connected to an autosampler was fully automated and clean-up of the samples took one minute. In addition, in the case of plasma samples the same plug of sorbent could be used for about 100 extractions before it was discarded.

    A further aim of this work was to increase sample preparation throughput. To do that disposable pipette tips were packed with a plug of porous polymer monoliths as sample adsorbent and were then used in connection with 96-well plates and LC-MS-MS. When roscovitine in human plasma and water samples was used as model substance, a 96-plate was handled in two minutes.

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    FULLTEXT01
  • 28.
    Altun, Zeki
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    New Techniques for Sample Preparation in Analytical Chemistry: Microextraction in Packed Syringe (MEPS) and Methacrylate Based Monolithic Pipette Tips2008Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Sample preparation is often a bottleneck in systems for chemical analysis. The aim of this work was to investigate and develop new techniques to address some of the shortcomings of current sample preparation methods. The goal has been to provide full automation, on-line coupling to detection systems, short sample preparation times and high-throughput.

    In this work a new technique for sample preparation that can be connected on-line to liquid chromatography (LC) and gas chromatography (GC) has been developed. Microextraction in packed syringe (MEPS) is a new solid-phase extraction (SPE) technique that is miniaturized and can be fully automated. In MEPS approximately 1 mg of sorbent material is inserted into a gas tight syringe (100-250 μL) as a plug. Sample preparation takes place on the packed bed. Evaluation of the technique was done by the determination of local anaesthetics in human plasma samples using MEPS on-line with LC and tandem mass spectrometry (MS-MS). MEPS connected to an autosampler was fully automated and clean-up of the samples took about one minute. In addition, in the case of plasma samples the same plug of sorbent could be used for about 100 extractions before it was discarded.

    A further aim of this work was to increase sample preparation throughput. To do that disposable pipette tips were packed with a plug of porous polymer monoliths as sample adsorbent and were then used in connection with 96-well plates and LC-MS-MS. The evaluation of the methods was done by the analysis of local anaesthetics lidocaine and ropivacaine, and anti-cancer drug roscovitine in plasma samples. When roscovitine and lidocaine in human plasma and water samples were used as model substances, a 96-plate was handled in about two minutes. Further, disposable pipette tips may be produced at low cost and because they are used only once, carry-over is eliminated.

    Download full text (pdf)
    FULLTEXT01
  • 29. Altun, Zeki
    et al.
    Abdel-Rehim, M.
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    New trends in sample preparation: On-line microextraction in packed syringe (MEPS) for LC and GC applications. Part III Determination and validation of local anaesthetics in human plasma samples using a cation-exchange sorbent and MEPS-LC-MS-MS2004In: J. Chromatogr. B, 813 (2004) 129-135Article in journal (Refereed)
  • 30.
    Altun, Zeki
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Andersson, Lars I.
    AstraZeneca R&D Södertälje, DMPK & BAC, Södertälje, Sweden.
    Blomberg, Lars G.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Abdel-Rehim, Mohamed
    Karlstad University, Division for Business and Economics.
    Some Factors Affecting the Performance of Microextraction in Packed Syringe (MEPS)Manuscript (Other academic)
  • 31. Altun, Zeki
    et al.
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Use of carbon dioxide and ammonia as nebulizer gases in mass spectrometry2002In: Rapid Comm. Mass Spectrometry, 16 (2002) 738-739Article in journal (Refereed)
  • 32.
    Altun, Zeki
    et al.
    Karlstad University, Division for Chemistry.
    Blomberg, Lars G.
    Karlstad University, Division for Chemistry.
    Abdel-Rehim, Mohamed
    Karlstad University, Division for Chemistry.
    Increasing Sample Preparation Throughput Using Monolithic Methacrylate Polymer as Packing Material for 96-Tips: 2 Minutes per 96-Well Plate2005Manuscript (preprint) (Other academic)
  • 33. Altun, Zeki
    et al.
    Hjelmström, Anette
    Abdel-Rehim, Mohamed
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Surface Modified Polypropylene Pipette Tips Packed with a Monolithic Plug of Adsorbent for High Throughput Sample Preparation2007In: J. Sep. Sci., 30 (2007) 1964-1972Article in journal (Refereed)
  • 34. Altun, Zeki
    et al.
    Hjelmström, Anette
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Abdel-Rehim, Mohamed
    Evaluation of monolithic packed 96-tips for solid-phase extraction of local anesthetics from human plasma for quantitation by liquid chromatography tandem mass spectrometry2008In: J. Liq. Chromatogr. & Relat. Technol , 31 (2008) 743-751Article in journal (Refereed)
  • 35. Altun, Zeki
    et al.
    Jagerdeo, E.
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Abdel-Rehim, M.
    Drug screening using microextraction in packed syringe (MEPS) / LC-MS utilizing monolithic-based sorbent material,2006In: Journal of Liquid Chromatography and Related Technologies, 29 (2006) 829-839Article in journal (Refereed)
  • 36.
    Ammothum Kandy, Akshay Krishna
    et al.
    Department of Chemistry, Ångström Laboratory, Uppsala University, Box 538, Uppsala, Sweden.
    Wadbro, Eddie
    Umeå universitet, Institutionen för datavetenskap.
    Aradi, Bálint
    Bremen Center for Computational Materials Science, University of Bremen, Am Fallturm 1, Bremen, Germany.
    Broqvist, Peter
    Department of Chemistry, Ångström Laboratory, Uppsala University, Box 538, Uppsala, Sweden.
    Kullgren, Jolla
    Department of Chemistry, Ångström Laboratory, Uppsala University, Box 538, Uppsala, Sweden.
    Curvature Constrained Splines for DFTB Repulsive Potential Parametrization2021In: Journal of Chemical Theory and Computation, ISSN 1549-9618, E-ISSN 1549-9626, Vol. 17, no 3, p. 1771-1781Article in journal (Refereed)
    Abstract [en]

    The Curvature Constrained Splines (CCS) methodology has been used for fitting repulsive potentials to be used in SCC-DFTB calculations. The benefit of using CCS is that the actual fitting of the repulsive potential is performed through quadratic programming on a convex objective function. This guarantees a unique (for strictly convex) and optimum two-body repulsive potential in a single shot, thereby making the parametrization process robust, and with minimal human effort. Furthermore, the constraints in CCS give the user control to tune the shape of the repulsive potential based on prior knowledge about the system in question. Herein, we developed the method further with new constraints and the capability to handle sparse data. We used the method to generate accurate repulsive potentials for bulk Si polymorphs and demonstrate that for a given Slater-Koster table, which reproduces the experimental band structure for bulk Si in its ground state, we are unable to find one single two-body repulsive potential that can accurately describe the various bulk polymorphs of silicon in our training set. We further demonstrate that to increase transferability, the repulsive potential needs to be adjusted to account for changes in the chemical environment, here expressed in the form of a coordination number. By training a near-sighted Atomistic Neural Network potential, which includes many-body effects but still essentially within the first-neighbor shell, we can obtain full transferability for SCC-DFTB in terms of describing the energetics of different Si polymorphs.

  • 37.
    Amruth, C.
    et al.
    Lodz University of Technology, Poland.
    Szymanski, Marek Zdzislaw
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013). Örebro University.
    Luszczynska, Beata
    Lodz University of Technology, Poland.
    Ulanski, Jacek
    Lodz University of Technology, Poland.
    Inkjet printing of super yellow: Ink formulation, film optimization, OLEDs fabrication, and transient electroluminescence2019In: Scientific Reports, E-ISSN 2045-2322, Vol. 9, p. 1-10, article id 8493Article in journal (Refereed)
    Abstract [en]

    Inkjet printing technique allows manufacturing low cost organic light emitting diodes (OLEDs) in ambient conditions. The above approach enables upscaling of the OLEDs fabrication process which, as a result, would become faster than conventionally used vacuum based processing techniques. In this work, we use the inkjet printing technique to investigate the formation of thin active layers of well-known light emitting polymer material: Super Yellow (poly(para-phenylene vinylene) copolymer). We develop the formulation of Super Yellow ink, containing non-chlorinated solvents and allowing stable jetting. Optimization of ink composition and printing resolution were performed, until good quality films suitable for OLEDs were obtained. Fabricated OLEDs have shown a remarkable characteristics of performance, similar to the OLEDs fabricated by means of spin coating technique. We checked that, the values of mobility of the charge carriers in the printed films, measured by transient electroluminescence, are similar to the values of mobility measured in spin coated films. Our contribution provides a complete framework for inkjet printing of high quality Super Yellow films for OLEDs. The description of this method can be used to obtain efficient printed OLEDs both in academic and in industrial settings.

    Download full text (pdf)
    fulltext
  • 38.
    An, Wei
    et al.
    Brookhaven National Laboratory, USA.
    Baber, Ashleigh E.
    Brookhaven National Laboratory, USA.
    Xu, Fang
    Stony Brook University, USA.
    Soldemo, Markus
    KTH.
    Weissenrieder, Jonas
    KTH.
    Stacchiola, Dario
    Brookhaven National Laboratory, USA.
    Liu, Ping
    Brookhaven National Laboratory, USA.
    Mechanistic Study of CO Titration on CuxO/Cu(111) (x <= 2) Surfaces2014In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 6, no 8, p. 2364-2372Article in journal (Refereed)
    Abstract [en]

    The reducibility of metal oxides is of great importance to their catalytic behavior. Herein, we combined ambient-pressure scanning tunneling microscopy (AP-STM), X-ray photoemission spectroscopy (AP-XPS), and DFT calculations to study the CO titration of CuxO thin films supported on Cu(111) (CuxO/Cu(111)) aiming to gain a better understanding of the roles that the Cu(111) support and surface defects play in tuning catalytic performances. Different conformations have been observed during the reduction, namely, the 44 structure and a recently identified (5-7-7-5) Stone-Wales defects (5-7 structure). The DFT calculations revealed that the Cu(111) support is important to the reducibility of supported CuxO thin films. Compared with the case for the Cu2O(111) bulk surface, at the initial stage CO titration is less favorable on both the 44 and 5-7 structures. The strong CuxO <-> Cu interaction accompanied with the charge transfer from Cu to CuxO is able to stabilize the oxide film and hinder the removal of O. However, with the formation of more oxygen vacancies, the binding between CuxO and Cu(111) is weakened and the oxide film is destabilized, and Cu2O(111) is likely to become the most stable system under the reaction conditions. In addition, the surface defects also play an essential role. With the proceeding of the CO titration reaction, the 5-7 structure displays the highest activity among all three systems. Stone-Wales defects on the surface of the 5-7 structure exhibit a large difference from the 44 structure and Cu2O(111) in CO binding energy, stability of lattice oxygen, and, therefore, the reduction activity. The DFT results agree well with the experimental measurements, demonstrating that by adopting the unique conformation, the 5-7 structure is the active phase of CuxO, which is able to facilitate the redox reaction and the Cu2O/Cu(111)<-> Cu transition.

  • 39.
    Anderson, Fredrik
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    Rheological changes at the air-liquid interface and examining different kind of magnetic needles2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The main objective in this work was to learn how the instrument, the Interfacial Shear

    Rheometer (ISR400), worked and to investigate how the rheological properties, storage

    modulus (elasticity), G' and loss modulus (viscous), G'', changes when the surface

    pressure at the air-liquid interphase changes. The second objective were to examine the

    different kind of magnetic needles used in the experiments and to conclude which type of

    needle is best for its specific field of analysis.

    It was concluded that the relative heavy needle with mass 70.6 mg and length 50 mm

    was best for systems where the viscous and elastic components are significantly large,

    where the inertia of the needle is not dominant. It also worked of using the heavier needle

    for a system of phospholipids.

    For the hydroxystearic acid (HSA) experiment that were tested on NaCl sub-phase there

    was a clear improvement after switching from the heavy needle (mass 41.5 mg; length 51

    mm) to the relative lighter needle (mass 6.94 mg; length 34.7 mm). The values for the

    dynamic modulus therefore had a better agreement with reference literature.

    A spread layer of class II hydrophobins (HFBII) could be compressed to a surface

    pressure of 46 mNm-1. The G' and G'' values from the frequency sweep were discarded

    because the monolayer turned into a very viscous-like liquid, and the oscillating needle,

    after compression, was kind of stuck in the sub-phase and moved very staggering during

    a frequency sweep.

    The needle comparison experiment with silica particles 10 wt% Bindzil CC30 (BCC30),

    at pH 3.5 was done to see if there was any difference in the sensitivity for the needles at

    the interface which consisted of a pure 10 mM NaCl solution or a 10 mM NaCl solution

    with BCC30 added to it. The differences were negligible in terms of surface tension but

    there was a clear difference between the heavy needle and the light needle, when

    oscillating at higher frequencies (>≈6 rad/s).

    With this study, the understanding of ISR400 has increased largely. Several issues have

    been addressed and the results provide a good basis for further studies within the many

    areas the instrument can be used for. Despite the project's time limit, and the fact that the

    instrument was new and untested where the project was carried out, focus areas were

    prioritized so good results could be achieved within reasonable goals.

    Download full text (pdf)
    Rheological changes
  • 40.
    Andersson, Kerstin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Molecular properties of TCNQ and anions2023In: Theoretical Chemistry accounts, ISSN 1432-881X, E-ISSN 1432-2234, Vol. 142, no 6, article id 58Article in journal (Refereed)
    Abstract [en]

    The purpose of the work is to calculate accurate values of molecular properties of tetracyanoquinodimethane (TCNQ) and anions using the complete active space self-consistent field and complete active space second-order perturbation theory methods. The accuracy has been evaluated using several basis sets and active spaces. The calculated properties have, in many cases, been confirmed by experimental data (within parentheses), e.g., 9.54 eV (9.61 eV) and 3.36 eV (3.38 eV) for the ionization potential and electron affinity, respectively, of TCNQ; 3.12 eV (3.01 eV) and 3.54 eV (3.42 or 3.60 eV) for transition energies to the two lowest-lying excited singlet states of TCNQ; − 0.03, 0.46 and 1.44 eV (0, 0.5 and 1.4 eV) for electronic energies in electron attachment of TCNQ forming $$\hbox {TCNQ}^-$$; and 3.88 eV (3.71 eV) for the transition energy to the second lowest-lying excited singlet state of $$\hbox {TCNQ}^{2-}$$. Further, the calculations have brought insight into some experimental observations, e.g., the shape of the fluorescence spectrum of TCNQ at 3–4 eV.

    Download full text (pdf)
    fulltext
  • 41.
    Andersson, Kerstin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    The electronic spectrum of C602020In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 739, p. 1-5, article id 136976Article in journal (Refereed)
    Abstract [en]

    Using the CASSCF/CASPT2 methodology the electronic transitions HOMO → LUMO, HOMO → LUMO+1, HOMO-1 → LUMO and HOMO-2 → LUMO are determined for C60.Comparison to experiment suggests an accuracy better than 0.3 eV. Some illustrative examples are (with experimental data within parentheses) the first excited state, 3T2g, at 1.54 eV (1.60 eV), the two lowest-lying 1T1u states (for spin- and symmetry-allowed transitions) at 3.09 eV (3.08 eV) and 3.19 eV (3.30 eV) and the lowest singlet excited states (1Gg, 1T1g, 1T2g , 1Hg) at [1.84, 1.95] eV (1.90 eV with mainly 1Gg and 1T1g and minor 1T2g character).

  • 42. Andersson, Magnus
    et al.
    Lu, B.
    Abdel-Rehim, M.
    Blomberg, S.
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Capillary electrophoresis methods for the separation of the basic compound lidocaine and its metabolites2004In: Rapid Commun. Mass Spectr., 18 (2004) 2612-2618Article in journal (Refereed)
  • 43.
    Andersson, Magnus S.
    Karlstad University, Division for Chemistry.
    Capillary electrophoresis methods for the separation of the basic compound lidocaine and its metabolites2003Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    For the separation of the basic compound lidocaine and its metabolites a variety of capillary electrophoresis (CE) methods have been developed. This includes capillary zone electrophoresis (CZE), micellar electrokinetic chromatography (MEKC) and nonaqueous CE separations. The parameters affecting the separations were investigated and optimized.

    In CZE reproducible separations were obtained in both un-coated and polyacrylamide-coated fused silica capillaries using a TFA/TEA electrolyte at pH 2.5.

    The MEKC method: a low pH phosphate/Tris buffer containing the cationic surfactant cetyltrimethylammonium bromide (CTAB) was successfully validated in human plasma.

    A couple of nonaqueous methods were developed. One of the methods 70 mM ammonium formate and 2 M formic acid in acetonitrile/methanol (60:40 v/v) was used for capillary electrophoresis-electrospray mass spectrometry analysis. Reproducible determinations in human plasma were obtained. The sensitivity was improved compared to UV. The detection limits for lidocaine and the metabolites monoethylglycinexylidide (MEGX) and glycinexylidide (GX) were 69 nM, 130 nM and 337 nM respectively. Parameters such as sheath liquid composition, nebulizing gas pressure and drying gas temperature were considered.

    The results show that CE is a simple and powerful technique for the separation of basic compounds.

  • 44. Andersson, Magnus
    et al.
    Wan, H.
    Abdel-Rehim, M.
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Characterization of Lidocaine and its Metabolites in Human Plasma using Capillary Electrophoresis,1999In: J. Microcol. Sep., 11, (1999) 620-626Article in journal (Refereed)
  • 45. Andersson, M.B.O.
    et al.
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Electric field-assisted micro-packed HPLC,2001In: J. Sep. Sci. 24 (2001) 304-308Article in journal (Refereed)
  • 46. Andersson,, M.B.O.
    et al.
    King, J.W.
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Synthesis of fatty alcohol mixtures from oleochemicals in supercritical fluids,2000In: Green Chemistry, (2000) 230-234Article in journal (Refereed)
  • 47.
    Andersson, N.
    et al.
    BTG Instruments AB, Box 602, Säffle.
    Wilke, Caroline
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Germgård, Ulf
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Impact of dissolved lignin in peroxide bleaching2017In: PEERS Conference 2017: Maximizing Success Through Innovation, TAPPI Press , 2017, p. 597-604Conference paper (Refereed)
    Abstract [en]

    It has been demonstrated in previous studies that dissolved lignin carryover has a significant impact in oxygen delignification and chlorine dioxide stages. Specifically for chlorine dioxide stages, it has been shown that the total kappa number of the pulp, i.e. the sum of the fiber kappa number and the filtrate kappa number, corresponds very well to its bleach demand and should be used for accurate feedforward based control. Since peroxide also is commonly used for pulp bleaching, and gaining in popularity, the present study was conducted in order to investigate the basic relations and mechanisms, using laboratory peroxide bleaching experiments comparing different carryover lignin concentrations and types. The results show that in particular chlorine dioxide filtrates have significant negative impact on delignification and brightening, likely due to alkali consumption of e.g. dissolved lignin, and that compensation using a higher alkali charge will result in lower brightness at a given kappa number. The paper also touches upon the opportunities using advanced process control systems for bleach plants, and the process and economic improvements which can be made by properly accounting for disturbances such as carryover variability.

  • 48. Andersson, Niclas
    et al.
    Lindström, Tomas
    Tillämpad analytisk kemi inom massaindustrin1997Student thesis
  • 49.
    Andersson, Niclas
    et al.
    BTG Instruments AB, Saffle, Sweden..
    Wilke, Caroline
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Biazzo, Tom
    BTG Instruments AB, Saffle, Sweden..
    Van Fleet, Rick
    BTG Instruments AB, Saffle, Sweden..
    Germgård, Ulf
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    A new sensor and a novel control concept for optimized fiber line operation2014In: TAPPI Journal, ISSN 0734-1415, Vol. 13, no 10, p. 39-45Article in journal (Refereed)
    Abstract [en]

    Kraft and sulfite pulp mills use several consecutive process stages for pulp production. However, usually only one key pulp parameter is used for process control and that is the lignin content in the fibers, typically expressed as the kappa number. Even so, to improve process efficiency, more variables need to be monitored. To do that, a new sensor was developed, the dissolved lignin transmitter (DLT), along with a new control concept. The DLT measures the dissolved lignin content in the pulp slurry using a unique principle based on optical measurements. The device can measure the dissolved lignin inline at low consistency and at medium consistency. The sensor has two major applications: 1) improving the efficiency in washing stages and 2) optimizing chemical charges. Results from several mill trials have shown that the contribution from dissolved lignin in the filtrate portion of the pulp is up to 30% of the total bleach load, i.e., fiber and filtrate kappa number combined into the bleach plant. Hence, chemical savings can be achieved taking this component into account compared to only measuring the washed fiber kappa number. Application: The results of this study can help mills understand how to better control the pulping stages, which might lead to significant economic savings and better pollution control.

  • 50.
    Andersson, Niclas
    et al.
    BTG Instruments AB.
    Wilke, Caroline
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013). BTG Instruments AB.
    Biazzo, Tom
    BTG Americas Inc. .
    van Fleet, Rick
    BTG Americas Inc. .
    Germgård, Ulf
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering.
    A new sensor and a novel control concept for optimized fiberline operation2013In: 2013 PEERS Conference, Co-located with the 2013 International Bioenergy and Bioproducts Conference, TAPPI Press, 2013, p. 190-215Conference paper (Refereed)
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