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  • 501.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Cellulose, cellulose regenerates and derivatives2009Conference paper (Refereed)
  • 502.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Delignification and bleaching of the future pulp mill2002Conference paper (Refereed)
  • 503.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    New Cell. Innovative Biopolymers2006Conference paper (Refereed)
  • 504.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    New Cellulose Derivatives from Wood for High Value Products2007Conference paper (Refereed)
  • 505.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    The Pulp Mill biorefinery2006Conference paper (Refereed)
  • 506.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Axegård, Peter
    Modern hydrogen peroxide bleaching.1994Conference paper (Refereed)
  • 507.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Engström, Ann-Charlott
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Increase Reactivity of Dissolving Pulps by different pretreatments2006Conference paper (Refereed)
  • 508.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Engström, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Vehviläinen, M
    Tamperere University.
    Heikkilä, S
    Temperere University.
    Agnemo, Roland
    Domsjö Fabriker.
    Cellulose derivatives: improved accessibility and reactivity2005In: 13th ISWFPC: Vol 2, 2005, p. 121-126Conference paper (Refereed)
  • 509.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Freiholtz, Anna
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Formation of oxalic acid during bleaching1996Conference paper (Refereed)
  • 510.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Freiholtz, Anna
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    On the formation of oxalic acid in bleaching.1996Conference paper (Refereed)
    Abstract [en]

    In modern pulp mills with prodn. of bleached chem. pulp the increased closure of the bleach plant effluent water system will lead to increased concns. of a variety of dissolved org. substances.  Among these oxalic acid is one of the most detrimental due to the facile formation of insol. calcium oxalate once the pH-value is low enough to liberate calcium ions from the pulp.  The ppt. may cause severe prodn. problems.  Therefore, the formation of oxalic acid from the bleaching of kraft pulps with a variety of bleaching agents have been analyzed.  Two methods of anal. have been employed, viz. ion chromatog. and enzymic oxidn. to hydrogen peroxide.  The former is a std. method requiring a certain sample treatment whereas the latter may be used on line.  Anal. of the aq. phase after each bleaching stage in a O D EO D sequence reveals that oxalic acid can be formed in all stages with the oxygen stage being the predominant contributor.  A comparison between different bleaching agents applied to the same pulp again reveals oxygen as a major producer of oxalic acid.  The oxalic acid can be formed from both lignin and polysaccharides but expts. with isolated lignin indicates that the predominant part of the oxalic acid is formed from carbohydrates.       

  • 511.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gierer, Josef
    Jansbo, Kerstin
    Study on the Selectivity of Bleaching with Oxygen-Containing Species1989In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 43, no 6, p. 391-396Article in journal (Refereed)
    Abstract [en]

    In the bleaching of pulp, the term Selectivity is widely used but poorly defined.This work is an attempt to quantify the selectivity of bleaching with Oxygen-containing species by generating hydroxil radicals and measuring their reaction rates with some lignin and carbohydrate models. Results of this investigation show that the selectivity factor defined as the ratio of the rate constants for a given pair of lignin and carbohydrate models, lies between 5 and 6.

  • 512.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gierer, Josef
    Jansbo, Kerstin
    Reitberger, Torbjoern
    Chemiluminescences as a means of observing hydroxyl radicals in bleaching processes.1987In: Proc. 4th int. Symp. Wood Pulp chem., Paris, France, 1987, p. 283-284Conference paper (Refereed)
  • 513.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gierer, Josef
    Reitberger, Torbjoern
    Hydroxyl radicals in oxygen bleaching1985In: Proc. 3rd Int. Symp. Wood Pulp. Chem., 1985, p. 209-210Conference paper (Refereed)
  • 514.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gustavsson, Catrin
    Kadiric, Jasmin
    Teder, Ants
    Formation and dissolution/degradation of hexenuronic acids during kraft pulping of Eucalyptus Globulus.2001Conference paper (Refereed)
  • 515.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ibarra, David
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Köpcke, Viviana
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Larsson, Per Tomas
    Jääskeläinen, Anna-Stiina
    Production of dissolving grade pulps from non-wood paper grade pulps using enzymatic and chemical pre-treatments for the viscose process2010Conference paper (Refereed)
    Abstract [en]

    Cellulose is the most abundant biorenewable material, constitutes an important polymer since it is used as raw material for several products, e.g.  Paper and board but also cellulose-based products which have many important applications in the pharmaceutical, textile, food and paint industries.  A raw material with high cellulose content and low content of hemicelluloses, residual lignin, extractives and minerals is required for the prodn. of these products, e.g.  Cotton and dissolving grade pulp are used.  However, the high cost prodn. of dissolving grade pulps has aroused the possibility of upgrading paper grade pulps into dissolving pulps by selective removal of hemicelluloses and subsequent activation of the pulps.  This study reports the feasibility to produce dissolving grade pulps from different pulps, i.e.  Non-wood paper grade pulps and conventional hardwood kraft pulps, employing enzymic and chem. pretreatments.  A monocomponent endoglucanase and a xylanase followed by alk. extn. were tested in order to increase the accessibility and reactivity of the cellulose pulp and decrease the hemicellulose content, resp.  An optimization of these treatments in terms of enzyme dosage, incubation time and a possible combination of them was investigated.  The treatment effects on reactivity according to Fock's method, viscosity, hemicellulose content and mol. wt. distribution, using size exclusion chromatog. (SEC), were analyzed.  The characterization of cellulose structure after the enzymic and chem. treatments was investigated by different techniques.

  • 516.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Biointeractive fibres: A sustainable way of fighting bacteria by using antibacterial cellulosic fibres2010Conference paper (Refereed)
    Abstract [en]

    Bacterial growth is a risk of infection.  Antibiotics did long time seem to be a soln. to the problem, but now the consequences are seen, as antibiotic-resistant strains are evolving.  The substances are also eventually released into the environment, where they often are harmful to living organisms.  Antibacterial surfaces state another option.  However, a majority of the now existing surfaces are of leaching type i.e. assocd. with the same problems as the antibiotics.  The non-leaching are a safer option, but until now the fabrication has been a problem with use of e.g. org. solvents.  We present a sustainable way of forming an antibacterial material onto cellulose by using the polyelectrolyte multilayer technique.  By step-wise adsorbing oppositely charged polyelectrolytes in an aq. soln. contg. fibers, at room-temp., the surface of the fibers are modified.  The result is a non-leaching material with bacteria inhibiting properties.  Also the fabrication is quite safe, as polymers have shown lower toxicity to humans than their monomeric counterparts.  Cellulose is an excellent substrate for antibacterial surfaces.  It is easy to modify with the present technique and is in itself a sustainable materials, with multiple applications.  Combined this gives us in total a new, antibacterial material which also opens up for sustainable cellulose-based products.

  • 517.
    Ek, Monica K.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    NewCell, ReCell and some other cell: Some highlights from dissolving pulp projects2013In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 245Article in journal (Other academic)
  • 518.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    From Cellulose Accessibility to Polymer and Product Properties of Cellulose Derivatives2009Conference paper (Refereed)
  • 519.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Fardim, Pedro
    Maunu, Sirkka Liisa
    University of Helsinki.
    Nousiainen, Pertti
    Siika-Aho5, Matti
    Walkenström, Pernilla
    New cellulose derivatives from wood for high value products2008In: TAPPSA: Technical Association of the Pulp and Paper Industry of Southern Africa, ISSN 1029-0109, no September 2008Article in journal (Refereed)
    Abstract [en]

    Various pre-treatment methods to increase the accessibility of cellulose materials to swelling and reactive agents at different hierarchical levels, has been developed. It was demonstrated that enzymes are very efficient at increasing the cellulose reactivity. A new method to measure the reactivity and accessibility of the hydroxyl groups on cellulose was developed. Reversible addition-fragmentation chain transfer (RAFT) agents were synthesized and used further in esterification reactions with cellulose samples to prepare cellulose based graft-copolymers. MALDI-TOFMS was evaluated for characterization of cellulose derivatives. Methods to prepare electrospun fibres, casings, sponges and beads, were developed with target applications in pharmaceuticals and foods.

  • 520.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Köpcke, Viviana
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ibarra, David
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Larsson, Per Tomas
    Characterization of dissolving pulps produced from Kraft pulps2009Conference paper (Refereed)
  • 521.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lennholm, Helena
    A studies on the mechanism of the photo-yellowing of partially acetylated ground wood pulps.1991Conference paper (Refereed)
  • 522.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lennholm, Helena
    Iversen, Tommy
    A comment on the effect of carbonyl groups on the light-induced reversion of groundwood pulp1990In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 5, no 4, p. 159-160Article in journal (Refereed)
    Abstract [en]

    Sodium borohydride redn. of stone groundwood pulp from spruce (Picea abies) had no dramatic effect on the light-induced brightness reversion.  This indicates that the direct scission of phenacyl aryl ether linkages is not an important step in the initial chromophore formation.

  • 523.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lennholm, Helena
    Lindblad, Gunnar
    Iversen, Tommy
    A study of the photochromic behaviour of UV-irradiated mechanical pulps.1992In: Proc. 2nd European Workshop Lignocellulosic Pulp (EWLP), 1992, p. 183-186Conference paper (Refereed)
  • 524.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lennholm, Helena
    Lindblad, Gunnar
    Iversen, Tommy
    The light-induced colour reversion of groundwood pulps1991In: Proc 6th Int. Symp. Wood Pulp Chem., Melbourne, Australia, 1991, p. 439-442Conference paper (Refereed)
  • 525.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Westman, Eva-Helena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Karlsson, Josefin
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    CELL 28-Biointeractive fibers with antibacterial properties2008In: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY: Volume: 235, 2008, p. 28-CELL-Conference paper (Refereed)
    Abstract [en]

    Growth of bacteria on various surfaces may cause major concern if encountered in the wrong environment.  The ability to impart antimicrobial properties onto surfaces is therefore desirable.  Modification of both glass surfaces and cellulose membranes using weak polyelectrolytes as antimicrobial agent is presented.  The aim was to incorporate a known carrier of antimicrobial activity into a multilayer structure of adsorbed polyelectolytes at different surfaces and evaluate the antibacterial activities.  The approach involved screening for antimicrobial activity in soln. of modified and unmodified polymers.  The polymers were evaluated against gram-neg. E. coli and gram-pos. B. subtilis. In order to elucidate the mode of action of the polymers, the charge was detd.  This is done since earlier studies have shown that both charge and degree of hydrophobicity are of importance in terms of exerted activity.  Results show that the chosen polymers exert activity in the immobilized state.  Different techniques have been used to evaluate the mechanisms.

  • 526.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Westman, Eva-Helena
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Cellulose films and fibres with antibacterial properties2007Conference paper (Refereed)
  • 527.
    Ekelund, Maria
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Azhdar, Bruska
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Gedde, Ulf W.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Evaporative loss kinetics of di(2-ethylhexyl)phtalate (DEHP) from pristine DEHP and plasticized PVCManuscript (preprint) (Other academic)
  • 528.
    Ekelund, Maria
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Azhdar, Bruska
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hedenqvist, Mikael S
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Gedde, Ulf W
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Long-term performance of poly(vinyl chloride) cables, Part 2: Migration of plasticizer2008In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 93, no 9, p. 1704-1710Article in journal (Refereed)
    Abstract [en]

    Cable samples with plasticized poly(vinyl chloride) insulations were aged in air at temperatures between 80 and 155 degrees C. The concentrations of the plasticizer (di-(2-ethylhexyl) phthalate, DEHP) in the insulations of the aged cables were determined by extraction of samples in tetrahydrofuran followed by analysis of the extract by liquid chromatography. The plasticizer concentration data for different ageing times were analysed by numerical methods, fitting Fick's second law with a concentration-dependent diffusivity. The analysis showed that the transport of the plasticizer to the surrounding air phase was controlled by diffusion at 120 and 155 degrees C with an activation energy of 89 kJ mol(-1). The evaporation of the plasticizer from the outer boundary was rate controlling at lower temperatures (<= 100 degrees C), The rate of evaporation was initially constant and independent of the plasticizer concentration at both 80 and 100 degrees C. The activation energy for the initial DEHP loss rate from PVC at these temperatures was the same as that obtained for evaporation of pure DEHP on a glass plate at 60-100 degrees C measured by thermogravimetry, 98 2 kJ mol-1. Furthermore, the evaporation rate of pure DEHP on a glass plate was also of the same order of magnitude as the rate of plasticizer loss from the cable insulation. Extrapolation of the plasticizer loss rate data (from the cable at 80 degrees C and from pure liquid DEHP at temperatures between 60 and 100 IQ to 25 degrees C predicted a maximum loss of plasticizer of 1% over 25 years. This is in accordance with earlier presented data and with the data presented in this report.

  • 529.
    Ekelund, Maria
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Edin, Hans
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Gedde, Ulf W
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Long-term performance of poly(vinyl chloride) cables. Part 1: Mechanical and electrical performances2007In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 92, no 4, p. 617-629Article in journal (Refereed)
    Abstract [en]

    Cables insulated with plasticized poly(vinyl chloride) were aged in air at temperatures between 80 degrees C and 180 degrees C and their conditions were assessed by indenter modulus measurements, tensile testing, infrared (IR) spectroscopy and differential scanning calorimetry (DSC). Electrical testing of oven-aged cable samples was performed in order to relate the electrical functionality during a high-energy line break (HELB) to the mechanical properties and to establish a lifetime criterion. The mechanical data taken at room temperature after ageing could be superimposed with regard to ageing time and temperature. The ageing-temperature shift factor showed an Arrhenius temperature dependence. The jacketing material showed an immediate increase in stiffness (indenter modulus and Young's modulus) and a decrease in the strain at break on ageing; these changes were dominated by loss of plasticizer by migration which was confirmed by IR spectroscopy and DSC. The core insulation showed smaller changes in these mechanical parameters; the loss of plasticizer by migration was greatly retarded by the closed environment, according to data obtained by IR spectroscopy and DSC, and the changes in the mechanical parameters were due to chemical degradation (dehydrochlorination). A comparison of data obtained from this study and data from other studies indicates that extrapolation of data for the jacketing insulation can be performed according to the Arrhenius equation even down to service temperatures (20-50 degrees C). The low-temperature deterioration of the jacketing is, according to this scheme, dominated by loss of plasticizer by migration.

  • 530.
    Ekelund, Maria
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Fantoni, Paolo F.
    Gedde, Ulf W.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Thermal ageing assassment of EPDM/CSPE-insulated cables using advanced condition-monitoring techniques.Manuscript (preprint) (Other academic)
  • 531.
    Ekelund, Maria
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Gedde, Ulf W.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lifetime prediction : different strategies by example2009In: POLYMER DEGRADATION AND PERFORMANCE / [ed] Celina MC; Wiggins JS; Billingham NC, 2009, Vol. 1004, p. 159-169Conference paper (Refereed)
    Abstract [en]

    Two different approaches for lifetime prediction are presented. The underlying lifetime limiting processes have been identified in two cases. Mathematical expressions of chemical/physical relevance were used for the lifetime predictions for PE hot-water pipes and cables insulated with plasticized PVC. Accelerated testing, extrapolation and validation of the extrapolation by assessment of the remaining lifetime of objects aged during service conditions for 25 years were successfully applied to cables insulated with chlorosulfonated polyethylene. Polyolefin pipes exposed to chlorinated water showed a very complex deterioration scenario and it was only possible to find a method suitable for predicting the time for the depletion of the stabilizer system.

  • 532.
    Eklund, Tomas
    KTH, School of Chemical Science and Engineering (CHE).
    Utredning av orsaker till höga kopparhalter i Käppalaverkets slam2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Käppala wastewater treatment plant (WWTP) is located in Lidingö and currently treats water from over half a million people. Every year the Käppala plant produces about 30 000 t sludge. The nutritious sludge is then used as fertilizer on farmland. From 2007 until 2012 the copper content has increased in the produced sludge. Eventually the amount of copper has exceeded the allowed limit for spreading sludge on farmland (300 g copper/ha and year). So only a limited amount of sludge can be spread on the farmland. The limit is set to protect the soil and aquatic organisms since the divalent copper ion has toxic effects on the organisms. Even Bromma and Henriksdal WWTP have had the same increase in copper content in the sludge, but not as highas the Käppala plant.

    The largest part of the copper that ends up in the sludge is predicted to originates from copper pipes in households. That is the reason why a number of different parameters has been investigated in order to see how much each parameter affects the amount of copper that is dissolved in the drinking water. The parameters that affect the most are; pH, alkalinity andnatural organic matter (NOM). When pH is decreasing, more copper will dissolve to the drinking water, but when the alkalinity and the NOM content is increasing, more copper will dissolve to the drinking water. Even the temperature and the stagnation time is important for how fast corrosion of copper pipes will occurs. The Görväln plant purifies and supplies drinking water to the majority of the member municipalities of the Käppala plant. Lovö’s and Norsborg’swaterworks supply drinking water to the other municipalities within the catchment area of Käppala. The alkalinity has slightly increased in the Görväln plant from 2000 to present. This increase should only affect in a very small degree on the increase in copper content in the sludge of Käppala plant. There is no clear trend on the other parameters that is considered to have an influence on the copper content in the sludge.

    The sharp increase in copper content has probably other causes. In February 2009, the Käppala plant, together with Bromma and Henriksdal WWTP, changed analysis laboratory. The change of laboratory seemed to affect the results of the analysis giving higher values of copper contentin the sludge. The standard deviation is also greater in the analysis results of the samples after the change of laboratory compared to with the analysis results before the change of laboratory. However, the uncertainty of the analysis has varied over the years when the rising in the copper content in the sludge occurred. At Stockholm Vatten’s laboratory where samples were sent before the laboratory change was the uncertainty of the analysis very unspecific given. According to the analysis report, the result of the sample had an uncertainty of the analysis between 15-40 %. The samples were after the laboratory change sent to Eurofins laboratory in Lidköping. Here the uncertainty of the analysis has been diminished with the time. After the first years after the change the uncertainty of the analysis was 30 %. But after that the uncertainty of the analysis has declined to 15 %.

    The reason why the Käppala plant had a stronger increase of copper content in the sludge than in Bromma and Henriksdal WWTP is unknown. One explanation could be that the sludge conditioning process Kemicond affected the analysis result since a certain change in concentration could have occurred when the process was in operation. However, the copper content has not decreased as much as expected after Kemicond was liquidated. But the total amount of copper in to the Käppala plant has increased during the period when the copper content in the sludge was higher. This indicates that there are other underlying reasons for the increase of copper in the sludge.

  • 533.
    Ekström, Madeleine
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Mechanical Metallurgy.
    Development of a ferritic ductile cast iron for improved life in exhaust applications2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Due to coming emission legislations, the temperature is expected to increase in heavy-duty diesel engines, specifically in the hot-end of the exhaust system affecting components, such as exhaust- and turbo manifolds. Since the current material in the turbo manifold, a ductile cast iron named SiMo51, is operating close to its limits there is a need for material development in order to maintain a high durability of these components. When designing for increased life, many material properties need to be considered, for example, creep-, corrosion- and fatigue resistance. Among these, the present work focuses on the latter two up to 800°C improving the current material by additions of Cr, for corrosion resistance, and Ni, for mechanical properties. The results show improved high-temperature corrosion resistance in air from 0.5 and 1wt% Cr additions resulting in improved barrier layer at the oxide/metal interface. However, during oxidation in exhaust-gases, which is a much more demanding environment compared to air, such improvement could not be observed. Addition of 1wt% Ni was found to increase the fatigue life up to 250°C, resulting from solution strengthening of the ferritic matrix. However, Ni was also found to increase the oxidation rates, as no continuous SiO2-barrier layers were formed in the presence of Ni. Since none of the tested alloys showed improved material properties in exhaust gases at high temperature, it is suggested that the way of improving performance of exhaust manifolds is to move towards austenitic ductile cast irons or cast stainless steels. One alloy showing good high-temperature oxidation properties in exhaust atmospheres is an austenitic cast stainless steel named HK30. This alloy formed adherent oxide scales during oxidation at 900°C in gas mixtures of 5%O2-10%H2O-85%N2 and 5%CO2-10%H2O-85%N2 and in air. In the two latter atmospheres, compact scales of (Cr, Mn)-spinel and Cr2O3 were formed whereas in the atmosphere containing 5%O2 and 10%H2O, the scales were more porous due to increased Fe-oxide formation. Despite the formation of a protective, i.e. compact and adherent, oxide scale on HK30, exposure to exhaust-gas condensate showed a detrimental effect in form of oxide spallation and metal release. Thus, proving the importance of taking exhaust-gas condensation, which may occur during cold-start or upon cooling of the engine, into account when selecting a new material for exhaust manifolds. 

  • 534.
    El Azab, Ahmad
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Modeling of Biofuel Combustion2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Fortum Scandinavia’s future challenge is to develop the district heating system to be able to meet costumers and societies demand for affordable and sustainable heating. One way to reach those goals is to use biofuels in the coal-fired power and heating plant KVV6 at Värtaverket in Stockholm. Different types of biofuels could be used but it is important to understand their combustion processes and the chemical characteristics of the biofuels. During this project olive stone cross, palm shell kernel (PKS), lignin and the liquid biofuel crude glycerol where tested in a lab-scale combustor fitted with a quartz cylinder. The combustion process was filmed and the results showed that palm shell kernel is a very promising fuel to be used instead of coal, with glycerol used as a substituted for water to make paste, which is needed to be able to pump the fuel in to the PFBC at KVV6. The biofuels where also tested for alkali where the results showed that PKS have very low amounts of alkali while the glycerol have very high amounts which would be unfavorable in the PFBC at KVV6. Olive stone cross and lignin are also good substitutes for coal but they do have higher amounts of alkali compared to PKS.

  • 535.
    EL Khoury, Youssef
    KTH, School of Chemical Science and Engineering (CHE).
    Förnyelsebar plast från rapshalm2014Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Efterfrågan på förnyelsebara och miljövänliga produkter har ökat under de senaste åren. Biobaserade plaster anses vara en av de mest lovande innovationer.   

    Det övergripande målet med examensarbetet var att undersöka möjligheterna att utvinna xylan och glukomannan ur rapshalm. Metoden som utnyttjades var en hydrotermisk extraktion. Inverkan av temperatur, pH och tid studerades genom att tillämpa ett faktorförsök på två nivåer. En askhalt- och torrhalt-analys utfördes på produkterna för att dels bestämma andelen oorganiskt material, dels beräkna det totala utbytet. Hemicellulosans molekylvikt bestämdes med hjälp av en SEC-analys. Kolhydratsammansättningen och andelen lignin i varje prov avslöjdes genom att utföra en kolhydratanalys. Två väletablerade tekniker (NMR (Nuclear magnetic resonance) och FTIR (Fourier transform infrared spectroscopy)) användes i detta arbete för bestämning av strukturen. NMR utnyttjades för att studera förhållandet mellan sockret och sidogrupperna medan IR användes för identifiering av de funktionella grupperna som förekommer i varje prov. Hemicellulosan som togs fram i projektet användes till gjutning av plastfilmer vars mekaniska egenskaper studerades genom att utföra dragprovningar.  

    Resultaten påvisade ett högt utbyte av produkt i samband med höga koncentrationer av NaOH. Andelen oorganiskt material var högre för de prover som behandlades med enbart vatten jämfört med de prover som behandlades med alkali. IC-analysen påvisade att glukomannan utsöndras med vatten medan utbytet av xylan blir högre vid behandling med alkali. IC-analysen visade även att den specifika typen av xylan i den undersökta rapshalmen utgörs av arabinoglukuronoxylan. SEC-analysen fastställde att vattenbehandlade prover har en högre molekylvikt. Ett oväntat resultat var att mängden lignin som erhölls i de vattenbehandlade proverna var högre än de som erhölls vid alkalibehandling. Resultaten från NMR- och IR- analyserna påvisade förekomsten av polysackarider i de olika proven. Dragprovningen visade att jämnt fördelade andelar xylan och glukomannan tillsammans med en hög molekylvikt bidrog till en större förmåga hos materialet att kunna bemöta den ökade belastningen.

  • 536. Elawad, M.
    et al.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Mola, G. T.
    Yu, Z.
    Arbab, E. A. A.
    Enhanced performance of perovskite solar cells using p-type doped PFB:F4TCNQ composite as hole transport layer2019In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 771, p. 25-32Article in journal (Refereed)
    Abstract [en]

    Conjugated polymers have been widely used as hole transport materials (HTM) in the preparation of mesoscopic perovskite solar cells (PSCs). In this work, we employed p-type doped conducting polymer known as poly(9,9-dioctylfluorene-co-bis-N,N-(-4-butyl phenyl)-bis-N,N-phenyl-1,4-phenylenediamine) (PFB) as a hole transport material (HTM) in perovskite based solar cell. The effect of dopant concentration on the optical and electrical properties of PEB was investigated to optimize the electrical properties of the material for the best function of the solar cell. The highest power conversion efficiency of mesoscopic perovskite solar cells (PSCs), fabricated in this investigation, was found to be 14.04% which is 57% higher than that of pristine PFB hole transport layer. The UV–Vis absorption and Raman spectroscopy measurements confirm the occurrence of oxidation in a p-type doped PFB hole transport layer. This is attributed to the transfer of electrons from the highest occupied molecular orbital (HOMO) of PEB to the lowest unoccupied molecular orbital (LUMO) of F4TCNQ. The solar cells produced using p-type doped PFB:F4TCNQ composite not only improves device performances but also shows superior long-term stability. The optical, morphological and electrical properties of the doped composite PFB: F4TCNQ and newly fabricated devices are presented and discussed in this paper.

  • 537. Eldsäter, C.
    et al.
    Albertsson, A-C.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Impact of degradation mechanisms on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) during composting1997In: Acta Polymerica, ISSN 0323-7648, E-ISSN 1521-4044, Vol. 48, no 11, p. 478-483Article in journal (Refereed)
  • 538. Eldsäter, C.
    et al.
    Erlandsson, B.
    Renstad, R.
    Albertsson, A-C.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    The biodegradation of amorphous and crystalline regions in film-blown poly(ε-caprolactone)2000In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 41, no 4, p. 1297-1304Article in journal (Refereed)
  • 539. Eldsäter, Carina
    et al.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    Effect of abiotic factors on the degradation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in simulated and natural composting environments1999In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 64, no 2, p. 177-183Article in journal (Refereed)
  • 540.
    Elger, Ragna
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Modelling and experimental validation of the electrochemical behaviour of a li-ion battery during repetitive pulses of charge and discharge2004Conference paper (Refereed)
    Abstract [en]

    In this study, a mathematical model describing the electrochemical and thermal behaviour of a cylindrical lithium-ion battery during high rate discharge and charge using a pulse typical for hybrid electric vehicles (HEV) is validated against experimental data. Experiments on the battery were performed in various constant temperature environments during a repeated pulse using high rate charge and discharge. The results show that the voltage losses increase as the temperature is lowered. The measurements show that as a good approximation, the surface temperature during the pulses can be assumed constant. The open circuit potential of LiNi0.8Co0.15Al0.05 was measured using GITT-experiments. The temperature dependence of the open circuit potential of LiNi0.8Co0.15Al0.05 was shown to be negligible. The experimental data will be used to validate the battery model. Some of the model parameters have yet to be fitted to the experimental results before a good agreement between experimental and model results is obtained.

  • 541.
    Elm Svensson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Nanomaterials for high-temperature catalytic combustion2007Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Catalytic combustion is a promising technology for power applications, especially gas turbines. By using catalytic combustion ultra low emissions of nitrogen oxides (NOX), carbon monoxide (CO) and unburned hydrocarbons (UHC) can be reached simultaneously, which is very difficult with conventional combustion technologies. Besides achieving low emission levels, catalytic combustion can stabilize the combustion and thereby be used to obtain stable combustion with low heating-value gases. This thesis is focused on the high temperature part of the catalytic combustor. The level of performance demanded on this part has been proven hard to achieve. In order to make the catalytic combustor an alternative to the conventional flame combustor, more stable catalysts with higher activity have to be developed.

    The objective of this work was to develop catalysts with higher activity and stability, suitable for the high-temperature part of a catalytic combustor fueled by natural gas. A microemulsion-based preparation method was developed for this purpose in an attempt to increase the stability and activity of the catalysts. Supports known for their stability, magnesia and hexaaluminate, were prepared using the new method. The microemulsion method was also used to impregnate the prepared material with the more active materials perovskite (LaMnO3) and ceria (CeO2). It was shown that the microemulsion method could be used to prepare catalysts with better activity compared to the conventional methods. Furthermore, by using the microemulsion to apply active materials onto the support a significantly higher activity was obtained than when using conventional impregnation techniques.

    Since the catalysts will operate in the catalytic combustor for extended periods of time under harsh conditions, an aging study was performed. One of the most stable catalysts reported in the literature, LMHA (manganese-substituted lanthanum hexaaluminate), was included in the study for comparison purposes. The results show that LMHA deactivated much more strongly compared to several of the catalysts consisting of ceria supported on lanthanum hexaaluminate prepared by the developed microemulsion method.

  • 542.
    Elm Svensson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Nanotemplated High-Temperature Materials for Catalytic Combustion2008Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Catalytic combustion is a promising technology for heat and power applications, especially gas turbines. By using catalytic combustion ultra low emissions of nitrogen oxides (NOX), carbon monoxide (CO) and unburned hydrocarbons (UHC) can be reached simultaneously, which is very difficult with conventional combustion technologies. Besides achieving low emission levels, catalytic combustion can stabilize the combustion and thereby be used to obtain stable combustion with low heating-value gases. This thesis is focused on the high-temperature part of the catalytic combustor. The level of performance demanded on this part has proven hard to achieve. In order to make the catalytic combustor an alternative to the conventional flame combustor, more stable catalysts with higher activity have to be developed.

    The objective of this work was to develop catalysts with higher activity and stability, suitable for the high-temperature part of a catalytic combustor fueled by natural gas. Two template-based preparation methods were developed for this purpose. One method was based on soft templates (microemulsion) and the other on hard templates (carbon). Supports known for their stability, magnesia and hexaaluminate, were prepared using the developed methods. Catalytically active materials, perovskite (LaMnO3) and ceria (CeO2), were added to the supports in order to obtain catalysts with high activities and stabilities. The supports were impregnated with active materials by using a conventional technique as well as by using the microemulsion technique.

    It was shown that the microemulsion method can be used to prepare catalysts with higher activity compared to the conventional methods. Furthermore, by using a microemulsion to apply active materials onto the support a significantly higher activity was obtained than when using the conventional impregnation technique. Since the catalysts will operate in the catalytic combustor for extended periods of time under harsh conditions, an aging study was performed on selected catalysts prepared by the microemulsion technique. The stability of the catalysts was assessed by measuring the activity before and after aging at 1000 C in humid air for 100 h. One of the most stable catalysts reported in the literature, LMHA (manganese-substituted lanthanum hexaaluminate), was included in the study for comparative purposes. The results showed that LMHA deactivated much more strongly compared to several of the catalysts consisting of ceria supported on lanthanum hexaaluminate prepared by the developed microemulsion method.

    Carbon templating was shown be a very good technique for the preparation of high-surface-area hexaaluminates with excellent sintering resistance. It was found that the pore size distribution of the carbon used as template was a crucial parameter in the preparation of hexaaluminates. When a carbon with small pores was used as template, the formation of the hexaaluminate crystals was strongly inhibited. This resulted in a material with poor sintering resistance. On the other hand, if a carbon with larger pores was used as template, it was possible to prepare materials with hexaaluminate as the major phase. These materials were, after accelerated aging at 1400 C in humid air, shown to retain surface areas twice as high as reported for conventionally prepared materials.

  • 543.
    Elm Svensson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    High-surface-area lanthanum hexaaluminates by carbon templatingArticle in journal (Other academic)
  • 544.
    Elm Svensson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Preparation of hexaaluminate2008Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A method for preparing a hexaaluminate. The method comprises the steps of a) providing a porous template material, wherein pores having a pore size of about 5-200 nm form at least about 50% of the total pore volume; b) impregnating the material with a liquid comprising metal elements corresponding to the elements of said hexaaluminate to provide an impregnated material; c) drying the impregnated material to provide a dried material; d) optionally, repeating at least once step b), using the dried material, and step c); e) calcining the dried material in an inert atmosphere to provide a calcined material; and f) recovering the hexaaluminate by removing template material from the calcined material. A composition obtainable by such a method. A catalyst composition comprising a hexaaluminate, wherein the composition has an average surface area of at least about 9 m2/g after ageing of the composition in a moist high-temperature atmosphere. A supported catalyst comprising such a composition. Use of such a composition as a catalyst in a high-temperature application.

  • 545.
    Elm Svensson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Stability of hexaaluminate-based catalysts for high-temperature catalytic combustion of methane2008In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 84, no 1-2, p. 241-250Article in journal (Refereed)
    Abstract [en]

    Lanthanum hexaaluminate with a nominal composition of LaAl11O18 Was used to support 20 wt.% of LaMnO3 and CeO2. LaAl11O18 was prepared through co-precipitation of metal nitrates within the water phase of an isooctane/CFAB/1-butanol microemulsion. The stabilities of the prepared catalysts were assessed by measuring the activities for combustion of methane before and after aging at 1000 degrees C for 100h in air with 10 vol.% H2O. The activities were compared with LaMnAl11O19, due to its well-documented stability. It was shown that by using hydrothermal treatment of the microemulsion, a significantly higher surface area was obtained for the LaAl11O18. For LaMnO3, the reference support (Al2O3) was shown to be superior to LaAl11O18 as support, both in terms of activity and stability. Reactions between LaMnO3 and support were observed for all supports included in the study. For CeO2, LaAl11O18 was superior to Al2O3 as support. Deactivations of the CeO2 catalysts were linked to crystal growth of CeO2. LMHA deactivated strongly during aging; LaMnO3 on Al2O3 and several of the catalysts with CeO2 supported on LaAl11O18 showed a much more stable behavior.

  • 546.
    Elm Svensson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Synthesis of barium hexaaluminate by co-precipitation in microemulsionIn: Materials Chemistry and Physics, ISSN 0254-0584, E-ISSN 1879-3312Article in journal (Other academic)
  • 547.
    Elm Svensson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Lualdi, Matteo
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Catalytic combustion of methane over perovskite supported on lanthanum hexaaluminate prepared through the microemulsion method2007In: Studies in Surface Science and Catalysis, ISSN 0167-2991, Vol. 172, p. 465-468Article in journal (Refereed)
  • 548.
    Elm Svensson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Nassos, Stylianos
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Microemulsion synthesis of MgO-supported LaMnO3 for catalytic combustion of methane2006In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 117, no 4, p. 484-490Article in journal (Refereed)
    Abstract [en]

    Catalysts with 20% LaMnO3 supported on MgO have been prepared via CTAB-1-butanol-iso-octane-nitrate salt microemulsion. The preparation method was successfully varied in order to obtain different degrees of interaction between LaMnO3 and MgO as shown by TPR and activity tests after calcination at 900 degrees C. Activity was tested on structured catalysts with 1.5% CH4 in air as test gas giving a GHSV of 100,000 h(-1). The activity was greatly enhanced by supporting LaMnO3 on MgO compared with the bulk LaMnO3. After calcination at 1100 degrees C both the surface area and TPR profiles were similar, indicating that the preparation method is of little importance at this high temperature due to interaction between the phases. Pure LaMmO(3) and MgO were prepared using the same microemulsion method for comparison purposes. Pure MgO showed an impressive thermal stability with a BET surface area exceeding 30 m(2)/g after calcination at 1300 degrees C. The method used to prepare pure LaMnO3 appeared not to be suitable since the surface area dropped to 1.1 m(2)/g already after calcination in 900 degrees C.

  • 549. Elsander, Anna
    et al.
    Ek, Monica
    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.
    Oxalic acid formation during ECF and TCF bleaching of kraft pulp1997In: Proceedings Minimum Effluent Mills Symposium, 1997, p. 63-66Conference paper (Refereed)
    Abstract [en]

    The formation of oxalic acid (I) during bleaching of softwood kraft pulp was studied.  Bleaching agents used were O, H2O2, ClO2, peracetic acid (II), and O3.  The formation of I acid increased linearly with the decrease in kappa no.  II bleaching gave less I than the other bleaching agents.  In O3 bleaching ∼1/3 of the formed I was adsorbed on the pulp and not released until a later stage.

  • 550.
    El-Seedi, Hesham R.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. Uppsala University, Sweden.
    Azeem, Muhammad
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. COMSATS Institute of Information Technology, Pakistan.
    Khalil, Nasr S.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. Agricultural Research Centre, Egypt.
    Sakr, Hanem H.
    Khalifa, Shaden A. M.
    Awang, Khalijah
    Saeed, Aamer
    Farag, Mohamed A.
    AlAjmi, Mohamed F.
    Pålsson, Katinka
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Borg-Karlson, Anna-Karin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Essential oils of aromatic Egyptian plants repel nymphs of the tick Ixodes ricinus (Acari: Ixodidae)2017In: Experimental & applied acarology, ISSN 0168-8162, E-ISSN 1572-9702, Vol. 73, no 1, p. 139-157Article in journal (Refereed)
    Abstract [en]

    Due to the role of Ixodes ricinus (L.) (Acari: Ixodidae) in the transmission of many serious pathogens, personal protection against bites of this tick is essential. In the present study the essential oils from 11 aromatic Egyptian plants were isolated and their repellent activity against I. ricinus nymphs was evaluated Three oils (i.e. Conyza dioscoridis L., Artemisia herba-alba Asso and Calendula officinalis L.) elicited high repellent activity in vitro of 94, 84.2 and 82%, respectively. The most active essential oil (C. dioscoridis) was applied in the field at a concentration of 6.5 A mu g/cm(2) and elicited a significant repellent activity against I. ricinus nymphs by 61.1%. The most repellent plants C. dioscoridis, C. officinalis and A. herba-alba yielded essential oils by 0.17, 0.11 and 0.14%, respectively. These oils were further investigated using gas chromatography-mass spectrometry analysis. alpha-Cadinol (10.7%) and hexadecanoic acid (10.5%) were the major components of C. dioscoridis whereas in C. officinalis, alpha-cadinol (21.2%) and carvone (18.2%) were major components. Artemisia herba-alba contained piperitone (26.5%), ethyl cinnamate (9.5%), camphor (7.7%) and hexadecanoic acid (6.9%). Essential oils of these three plants have a potential to be used for personal protection against tick bites.

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