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  • 1. Aarts, Mark
    et al.
    Reiser, Alain
    Laboratory for Nanometallurgy, ETH Zürich, Department of Materials, Vladimir-Prelog-Weg 1-5/10, Zürich, Switzerland.
    Spolenak, Ralph
    Alarcon-Llado, Esther
    Confined pulsed diffuse layer charging for nanoscale electrodeposition with an STM2022In: Nanoscale Advances, ISSN 25160230, Vol. 4, no 4, p. 1182-1190Article in journal (Refereed)
  • 2. Abbasalizadeh, Aida
    et al.
    Malfliet, Annelies
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Sietsma, Jilt
    Yang, Yongxiang
    Electrochemical Extraction of Rare Earth Metals in Molten Fluorides: Conversion of Rare Earth Oxides into Rare Earth Fluorides Using Fluoride Additives2017In: JOURNAL OF SUSTAINABLE METALLURGY, ISSN 2199-3823, Vol. 3, no 3, p. 627-637Article in journal (Refereed)
    Abstract [en]

    In the present research on rare earth extraction from rare earth oxides (REOs), conversion of rare earth oxides into rare earth fluorides with fluoride fluxes is investigated in order to overcome the problem of low solubility of the rare earth oxides in molten fluoride salts as well as the formation of oxyfluorides in the fluorination process. Based on thermodynamic calculations, a series of experiments were performed for converting the rare earth oxides into rare earth fluorides using AlF3, ZnF2, FeF3, and Na3AlF6 as fluorinating agents in a LiF-Nd2O3 system. The formation of neodymium fluoride as a result of the reactions between these fluxes and neodymium oxide is confirmed. The rare earth fluoride thus formed can subsequently be processed through the electrolysis route in the same reactor, and rare earth metal can be produced as the cathodic deposit. In this concept, the REO dissolution in molten fluorides would become unnecessary due to the complete conversion of the oxide into the fluoride, REF3. The results of XRD and EPMA analysis of the reacted samples indicate that AlF3, ZnF2, and FeF3 can act as strong fluorinating agents for the neodymium oxide giving rise to a complete conversion of neodymium oxide into neodymium fluoride.

  • 3. Abbasalizadeh, Aida
    et al.
    Malfliet, Annelies
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Sietsma, Jilt
    Yang, Yongxiang
    Electrochemical Recovery of Rare Earth Elements from Magnets: Conversion of Rare Earth Based Metals into Rare Earth Fluorides in Molten Salts2017In: Materials transactions, ISSN 1345-9678, E-ISSN 1347-5320, Vol. 58, no 3, p. 400-405Article in journal (Refereed)
    Abstract [en]

    In the present work, selective extraction of rare earth (RE) metals from NdFeB magnets is investigated by studying the effects of various fluxes, viz. AlF3, ZnF2, FeF3 and Na3AlF6 in the LiF-NdFeB system. The aim is to convert RE from RE magnet into the fluoride salt melt. The results show the complete selective separation of neodymium (also dysprosium) from the magnet and formation of rare earth fluoride, leaving iron and boron unreacted. The formed rare earth fluoride can subsequently be processed in the same reactor through an electrolysis route so that RE can be deposited as a cathode product. The results of XRD and EPMA analysis of the reacted samples indicate that AlF3, ZnF2 and FeF3 can act as strong fluorinating agents for extraction of rare earth from NdFeB magnet, converting the RE to REF3. The results confirm the feasibility of the rare earth metals recovery from scrap NdFeB magnet as raw material. The fluoride conversion- electrolysis route suggested in the present work enables the extraction of rare earth metals in a single step using the above-mentioned fluxes.

  • 4.
    Abdalla, Abdulbasit
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Odgren, Emilia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Biodiesel production from rape seed oil catalyzed by calcium oxide doped with lithium2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Biodiesel ses som ett av de främsta substituten för fossila bränslen, då den relativt enkelt kan appliceras i redan existerande dieselmotorer. Dagens produktion av biodiesel använder sig av homogena katalysatorer som inte återanvänds i processen, men för en mer cirkulär och i längden en billigare process ses heterogena katalysatorer som ett alternativ. Syftet med denna studie var att undersöka litium dopad kalciumoxid katalytiska egenskaper, de optimala förhållandena för reaktionen och även kinetiken för reaktionen. Den valda katalysatorn syntetiserades med kalcinering och sedan testades den katalytiska förmågan i reaktionen vid olika reaktionsförhållanden, för att finna de optimala förhållandena. Även katalysatorns fysiska egenskaper analyserades och kinetiken för reaktionen. De optimala förhållanden för transesterifieringen bestämdes till 3 h, 1:6 olja- metanolförhållande, 60°C och 5 vikts% katalysator, där 96% utbyte av biodiesel uppnåddes. Övriga utbyten från de andra försöken var betydligt lägre, vilket kan bero på icke optimala förhållanden, men även relativ dålig katalytisk förmåga. Ytarea och porstorlek konstateras vara små, vilket påverkar den katalytiska förmågan negativt. Anledningen till katalysatorns egenskaper beror huvudsakligen på tillverkningsprocessen, men även mängden litium i dopningen. Kinetiken visar en oväntad reaktionsutveckling med initialt hög koncentration FAME (Fatty acid Methylester), vilket troligen beror på felkällor.

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  • 5.
    Abdel-Magied, Ahmed Fawzy
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery. Nuclear Materials Authority. P. O. Box 530, El Maadi, Cairo, Egypt.
    Abdelhamid, Hani Nasser
    Assiut University.
    Ashour, Radwa M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery. Nuclear Materials Authority. P. O. Box 530, El Maadi, Cairo, Egypt.
    Fu, Le
    Central South University.
    Dowaidar, Moataz
    King Fahd University of Petroleum and Minerals (KFUPM).
    Xia, Wei
    Uppsala University.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Magnetic Metal-Organic Frameworks for Efficient Removal of Cadmium(II), and Lead(II) from Aqueous Solution2022In: Journal of Environmental Chemical Engineering, ISSN 2213-3437, p. 107467-107467, article id 107467Article in journal (Refereed)
    Abstract [en]

    Efficient and convenient methods for the removal of toxic heavy metal ions especially Cd(II) and Pb(II) from aqueous solutions is of great importance due to their serious threat to public health and the ecological system. In this study, two magnetic metal-organic frameworks (namily: Fe3O4@ZIF-8, and Fe3O4@UiO-66–NH2) were synthesized, fully characterized, and applied for the adsorption of Cd(II) and Pb(II) from aqueous solutions. The adsorption efficiencies for the prepared nanocomposites are strongly dependent on the pH of the aqueous solution. The maximum adsorption capacities of Fe3O4@UiO-66–NH2, and Fe3O4@ZIF-8 at pH 6.0 were calculated to be 714.3 mg·g 1, and 370 mg·g 1 for Cd(II), respectively, and 833.3 mg·g 1, and 666.7 mg·g 1 for Pb(II), respectively. The adsorption process follows a pseudo-second-order model and fit the Langmuir isotherm model. Moreover, the thermodynamic studies revealed that the adsorption process is endothermic, and spontaneous in nature. A plausible adsorption mechanism was discussed in detail. The magnetic adsorbents: Fe3O4@ZIF-8, and Fe3O4@UiO-66–NH2 showed excellent reusability, maintaining the same efficiency for at least four consecutive cycles. These results reveal the potential use of magnetic Fe3O4@ZIF-8, and Fe3O4@UiO-66–NH2 as efficient adsorbents in removing Cd(II) and Pb(II) from aqueous solutions.

  • 6.
    Abdel-Magied, Ahmed Fawzy
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Nasser Abdelhamid, Hani
    Ashour, Radwa M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Zou, Xiaodong
    Stockholms Universitet.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Hierarchical porous zeolitic imidazolate framework nanoparticles for efficient adsorption of rare-earth elements2019In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 278, p. 175-184Article in journal (Refereed)
    Abstract [en]

    Hierarchical porous zeolitic imidazolate frameworks nanoparticles (ZIF-8 NPs) were synthesized at room temperature via a template-free approach under dynamic conditions (stirring) using water as a solvent. The ZIF-8 NPs were evaluated as adsorbents for rare earth elements (La3+, Sm3+ and Dy3+). Adsorption equilibrium was reached after 7h and high adsorption capacities were obtained for dysprosium and samarium (430.4 and 281.1 mg g(-1), respectively) and moderate adsorption capacity for lanthanum (28.8 mg g(-1)) at a pH of 7.0. The high adsorption capacitiese, as well as the high stability of ZIF-8 NPs, make the hierarchical ZIF-8 materials as an efficient adsorbent for the recovery of La3+, Sm3+ and Dy3+ from aqueous solution.

  • 7.
    Abdi, Sofia
    KTH, School of Chemical Science and Engineering (CHE).
    Preparation and process optimization of encapsulating cellulose microspheres2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Microspheres are spherically shaped particles within the size range of 1-1000 μm in diameter.

    Due to the their small size and round shape, microspheres show many advantages in various

    applications such as pharmaceuticals, composites and coatings. The microspheres can be

    customized to fit a specific application and are manufactured in various forms such as solid,

    hollow and encapsulating.

    Encapsulating cellulose microspheres have been produced in this project by the emulsionsolvent

    evaporation technique. The purpose of this study was to further investigate the

    possibility of producing encapsulating microspheres with a size range of 10-50 μm that will

    have a high encapsulation. A second purpose of this study was optimizing the emulsifier

    system for the preparation of these spheres. This has been accomplished by varying several

    process parameters such as type of emulsifiers and solvents to study the effect on morphology

    and encapsulation efficiency. The analyses of the spheres were performed with optical

    microscopy, thermal gravimetric analyzer (TGA) and scanning electron microscopy (SEM).

    The emulsifier type and concentration affected the encapsulation and size distribution but had

    no direct effect on the internal and external structure, which was multi-cellular and porous,

    respectively. The highest encapsulation in relation to average size was obtained with 0.1 v/v-

    % of the emulsifier mixture Emulsifier 1 (E1)/Emulsifier 2 (E2) (70/30 %). The solvent used

    to dissolve the polymer had a direct effect on encapsulation, a combination of Solvent 2 (S2)

    and Solvent 1 (S1) proved best for the three tested cellulose derivatives with low, medium and

    high number average molecular weight. The solvent also had an effect on the internal

    structure of the microspheres, becoming more core-shell when using the S1/S2 combination.

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  • 8.
    Abdirahman Ahmed, Fatima
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Reologistudie av vattenbaserade industrifärger2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The rheological properties of water-based paint have been studied and the parameters that were investigated were mobility, viscoelasticity, sagging and levelling. The methods that arepresented in this study can predict sagging before the paint is applied on a vertical surface. The purpose of this study is to understand how different paints behave when sprayed on a vertical surface. The main goal in this study is to develop a method that can predict sagging when the wet condition is 300 μm.

    The rheometer gave measurement data that could be graded on a scale. Every paint had a value on this graded scale. A "Shear Rate Loop Test" was used to grade the paints after a graphical analysis. The development on the graded scale gives the right information whether the paint sags or not.

    Different types of oscillation tests were performed and these tests were 3ITT, amplitude sweep and frequency sweep. Elastic and viscous behaviour were measured and they illustrated what behaviour was dominating in the paints. 28 water-based paints were analysed and the methods for these paints can predict how they flow on a vertical surface.

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  • 9.
    Abdullah, Rondek
    KTH, School of Chemical Science and Engineering (CHE).
    Study of the Eutrophication of Lake Vallentuna2012Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Lake Vallentuna is situated 20 km north of Stockholm, in Täby and Vallentuna municipalities. It is a shallow eutrophicated lake, with a maximum depth of 6, 0 meter and the turnover time of the lake is 1, 6 years. Lake Vallentuna has two inlets, which are Ormstaån in the North and Karbyån in the South. The outlet from Lake Vallentuna is Hagbyån in the South-West. Lake Vallentuna is, due to human activities, influenced by many contaminants, for example phosphorus and nitrogen, which contribute to the eutrophication.

    The natural state of Lake Vallentuna involves a high phosphorus concentration, since it is a lake among fields dominated by clay. The increased phosphorus levels depend on various sources, such as sewage, agriculture, and storm water.

    The aim of this project is to describe the present state of the lake and to predict the future changes. This report will also give phosphorus and calcium levels determined for Lake Vallentunna. By the examination of the chemical and physical parameters we could estimate the contribution of pollutants. To assess the lake condition, an excursion was made to collect samples and perform measurements in the field. The samples were collected from twelve different sites.

    The eight parameters measured in this study are conductivity, temperature, pH, COD, chlorinity, alkalinity, calcium and total phosphorus. The assessment of the lake was based on the guidelines from the Swedish Environmental Protection Agency ”Bedömningsgrunder för miljökvalitet”. We compared the measured values with those in the guidelines. One conclusion is that the Lake is heavily eutrophicated.

    Our measurements indicate that the incoming amount of phosphorus is bigger than the outgoing amount of phosphorus, which means that the amount of phosphorus in the lake increases at the time for the measurements. However, the main source of phosphorus in the lake water is the internal contribution from the sediments, which have been accumulated during many years. The measured values of phosphorus show that the lake is eutrophicated.

    Lake Vallentuna contains big amounts of phosphorus and metal ions (see also Adam Kazi’s diploma work on metal ions in Lake Vallentuna[19] ). The reason is that the lake is situated in a very contaminated area.

  • 10. Abel, S
    et al.
    Bäbler, Matthäus
    ETH, Inst Chem & Bioengn, Dept Chem & Appl Biosci.
    Arpagaus, C
    Mazzotti, M
    Stadler, J
    Two-fraction and three-fraction continuous simulated moving bed separation of nucleosides2004In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1043, no 2, p. 201-210Article in journal (Refereed)
    Abstract [en]

     A new experimental set-up and a new simulated moving bed (SMB) operation are presented in this work. A desktop SMB unit developed as a modification of the commercial AKTA(TM) explorer working platform has been utilized for the separation of different mixtures of nucleosides. Both two fraction and three fraction SMB separations have been carried out, the latter made possible by the adoption of a new SMB configuration and operating mode (three fraction SMB, 3F-SMB, operation). Experiments demonstrate the feasibility of the 3F-SMB operation, and confirm the trends predicted based on considerations about retention of the components to be separated along the unit. 

  • 11.
    Abitbol, Tiffany
    et al.
    Institute of Materials, School of Engineering, EPFL, 1015 Lausanne, Switzerland;Bioeconomy and Health, RISE Research Institutes of Sweden, SE-114 28 Stockholm, Sweden.
    Kubat, Mikaela
    Bioeconomy and Health, RISE Research Institutes of Sweden, SE-114 28 Stockholm, Sweden.
    Brännvall, Elisabet
    Bioeconomy and Health, RISE Research Institutes of Sweden, SE-114 28 Stockholm, Sweden.
    Kotov, Nikolay
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Johnson, C. Magnus
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Nizamov, Rustem
    Department of Mechanical and Materials Engineering, Faculty of Technology, University of Turku, FI-20014 Turku, Finland.
    Nyberg, Mikael
    Department of Mechanical and Materials Engineering, Faculty of Technology, University of Turku, FI-20014 Turku, Finland.
    Miettunen, Kati
    Department of Mechanical and Materials Engineering, Faculty of Technology, University of Turku, FI-20014 Turku, Finland.
    Nordgren, Niklas
    Bioeconomy and Health, RISE Research Institutes of Sweden, SE-114 28 Stockholm, Sweden.
    Stevanic, Jasna S.
    Bioeconomy and Health, RISE Research Institutes of Sweden, SE-114 28 Stockholm, Sweden.
    Guerreiro, Maria Pita
    Bioeconomy and Health, RISE Research Institutes of Sweden, SE-114 28 Stockholm, Sweden.
    Isolation of Mixed Compositions of Cellulose Nanocrystals, Microcrystalline Cellulose, and Lignin Nanoparticles from Wood Pulps2023In: ACS Omega, E-ISSN 2470-1343, Vol. 8, no 24, p. 21474-21484Article in journal (Refereed)
    Abstract [en]

    From a circular economyperspective, one-pot strategies for theisolation of cellulose nanomaterials at a high yield and with multifunctionalproperties are attractive. Here, the effects of lignin content (bleachedvs unbleached softwood kraft pulp) and sulfuric acid concentrationon the properties of crystalline lignocellulose isolates and theirfilms are explored. Hydrolysis at 58 wt % sulfuric acid resulted inboth cellulose nanocrystals (CNCs) and microcrystalline celluloseat a relatively high yield (>55%), whereas hydrolysis at 64 wt% gaveCNCs at a lower yield (<20%). CNCs from 58 wt % hydrolysis weremore polydisperse and had a higher average aspect ratio (1.5-2x),a lower surface charge (2x), and a higher shear viscosity (100-1000x).Hydrolysis of unbleached pulp additionally yielded spherical nanoparticles(NPs) that were <50 nm in diameter and identified as lignin bynanoscale Fourier transform infrared spectroscopy and IR imaging.Chiral nematic self-organization was observed in films from CNCs isolatedat 64 wt % but not from the more heterogeneous CNC qualities producedat 58 wt %. All films degraded to some extent under simulated sunlighttrials, but these effects were less pronounced in lignin-NP-containingfilms, suggesting a protective feature, but the hemicellulose contentand CNC crystallinity may be implicated as well. Finally, heterogeneousCNC compositions obtained at a high yield and with improved resourceefficiency are suggested for specific nanocellulose uses, for instance,as thickeners or reinforcing fillers, representing a step toward thedevelopment of application-tailored CNC grades.

  • 12.
    Abraham, Saron
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    High entropy oxide electrodes with ionic liquid electrolyte2022Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Metal-based high entropy oxides are considered promising electrode materials for use in Li- ion batteries. In this work, the most widely studied high entropy oxide Mg0.2Ni0.2Cu0.2Co0.2Zn0.2O (M-HEO) with rock salt structure was successfully synthesized by Modified Pechini synthesis, characterized by X-ray diffraction analysis, and investigated as anode active material (negative electrode) in a coin cell. M-HEO has the concept of entropy stabilisation of crystal structure in oxide system with the configurational entropy value of 1,6R which confirmed that M-HEO classified as high entropy oxide. 

    To test the electrochemical performance, full cells comprising M-HEO as anode, lithium manganese oxide (LMO) as cathode together with ionic liquid electrolyte were assembled to explore their potential for practical applications. The electrochemical cycling performance was studied by two electrochemical experiments which are three-electrode cyclic voltammetry and galvanostatic charge/discharge. The cyclic voltammetry measurement was used to determine the behaviour of the system such as potential window and scan rate, while galvanostatic charge/discharge was used to determine the performance of the battery over time by applying constant current. 

    The results demonstrate that high entropy oxide possess a stable structure. This points out the direction for the preparation of M-HEOs with stable structure and excellent performance and provides a promising candidate for anode materials for LIBs.

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  • 13.
    Acat, Sergulan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Recovery of critical metals from secondary streams2022Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Mass amounts of secondary waste are generated annually from different parts of society. Most of the waste ends up either in landfills or in incineration plants. Several of these streams contain valuable metals that can be recovered [1]. In 2020, the European Commission reported the fourth list of the critical materials. The list includes a total of 30 critical materials. Several metals are critical because they are vital for developing new products. Another aspect is the risk of supply in the future, as the EU is dependent on importing critical materials from several countries. Utilizing secondary streams would be an effective way to recycle critical materials. 

    The study aimed to recover metals from secondary streams using ultrasound-assisted extraction and organic acids. The goal has been to characterize the streams to see which critical metals are present and to quantify them then. Furthermore, the goal has been to investigate the effect of ultrasound, compare the extraction with alternative processes, and provide suggestions for improvements for higher extraction for future studies. 

    This report review various metallurgical processes for recycling metals, followed by an experimental study of metal extraction from secondary streams with ultrasound assistance. Secondary streams investigated in this study were the NMC type Lithium-ion batteries (LiBs), three kinds of bottom ashes and oil shale ash from Ragn Sells AB. The effect of acid species and extraction time on metal extraction were investigated with ultrasound assistance. Inductively coupled plasma-optical emission spectrometry (ICP-OES) was used as an analysis method to characterize the ion concentrations in extracted solutions. 

    The result showed that Al, Li, Mn, Co, and Ni are interesting for metal recycling in lithium batteries. The bottom ash contained critical metals such as rare-earth elements (Ce, Dy, Er, Gd, Sc, Tb, Y) and Co, Ga, Li, V, Sb and Ru, Zn, Al, Ca, Cu, Mg, P, Ti and S. Metals such as Bi, Pd, Pt, and Rh varied between different bottom ashes. The result for the oil shale ash showed rare-earth elements such as Ce, Dy, Er, Eu, Sc, Tb, and Y and other critical metals such as Zn, Co, Cu, Ga, Li, V, Sb, Ge, Rh, Al, Ca, Mg, P, Ti, and S. 

    In ultrasound-assisted extraction, optimal leaching was achieved for a specific time for each stream and metal, respectively. In this study, the optimal leaching time for rare-earth elements was 200 s, 60 min and 30 min for bottom ash from Plant A (0-2 mm), Plant B (0-2 mm) and (0- 1 mm). Other critical metals were at 10 min and 200 s. The optimal leaching time for the oil shale ash was 30 min for rare-earth elements and 15 min for other critical metals. Both organic acids in lithium batteries showed the highest leaching at 60 min in ultrasound-assisted extraction. 

  • 14.
    Acevedo Gomez, Yasna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    On Gas Contaminants, and Bipolar Plates in Proton Exchange Membrane Fuel Cells2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The proton exchange membrane (PEM) fuel cell is an electrochemical device that converts chemical energy into electrical energy through two electrocatalytic reactions. The most common catalyst used is platinum on carbon (Pt/C), which has shown the best performance in the fuel cell until now. However, the drawback of this catalyst is that it does not tolerate impurities, and both hydrogen and oxygen may carry small amounts of impurities depending on the production sources. The purpose of this thesis is to understand the effect of two impurities that are less investigated, i.e., ammonia, which may accompany the hydrogen rich reformates from renewable sources, and nitrogen dioxide, which may come from air pollution. The mechanism of contamination and an adequate recovery method for the respective contaminant are studied. Additionally, electroplated bipolar plates with Ni-Mo and Ni-Mo-P coatings were tested as alternatives to stainless steel and carbon materials.

    The results show that ammonia not only provokes changes in the polymer membrane but also in the oxygen reduction reaction (ORR), hydrogen oxidation reaction (HOR) and catalyst ionomer in both electrodes. The extent of performance recovery after the contamination depends on the concentration used and the exposure time. In contrast, nitrogen dioxide affects the catalyst in the electrode directly; the contamination is related to side reactions that are produced on the catalyst’s surface. However, NO2 is not attached strongly to the catalyst and it is possible to restore the performance by using clean air. The time the recovery process takes depends on the potential applied and the air flow.

    Finally, the evaluation of electroplated Ni-Mo and Ni-Mo-P on stainless steel by ex situ and in situ studies shows that these coatings reduce the internal contact resistance (ICR) and the corrosion rate of the stainless steel considerably. However, the in situ experiments show that phosphorus addition to the coating does not improve the fuel cell performance; thus, the Ni-Mo alloy is found to be a promising choice for electroplating stainless steel bipolar plates.

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  • 15.
    Acevedo Gomez, Yasna
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lagergren, Carina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Effect of nitrogen dioxide impurities on PEM fuel cell performanceManuscript (preprint) (Other academic)
    Abstract [en]

    Air is the most practical and economical oxidant to feed to the cathode in a proton exchange membrane fuel cell (PEMFC). However, the air is accompanied by small amounts of impurities that affect the performance of the fuel cell. Among these, nitrogen dioxide is the impurity that has been least investigated, and its effect is not fully understood. In this study, a possible mechanism is proposed based on the contamination of the fuel cell at different concentrations and adsorption potentials, and by employing stripping cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The results at different concentrations showed that the catalyst sites are blocked by the adsorption of NO2, and that there is a non-linear relationship between the concentration and degradation. The degradation is suggested to be related to the formation of intermediate species, as also shown by the pseudo-inductive impedance at the concentration of 100 and 200 ppm. Furthermore, the cyclic voltammetry showed that there is an oxidation to NO3- at 1.05 V, followed by the reduction of this specie to NO2- at 0.68 V, and a subsequent reduction of NO2- to N2O and/or NH2OH.

  • 16.
    Acevedo Gomez, Yasna
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lagergren, Carina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Performance recovery after contamination with nitrogen dioxide in a PEM fuel cellManuscript (preprint) (Other academic)
    Abstract [en]

    While the market of fuel cell vehicles is increasing, these vehicles will still coexist with combustion engine vehicles on the roads and will be exposed to an environment with significant amounts of contaminants that will decrease the durability of the fuel cell. In order to investigate different recovery methods, a PEM fuel cell is in this study contaminated with 100 ppm of NO2 at the cathode side. The possibility to recover the cell performance is studied by using different airflow rates, different current densities, and by subjecting the cell to successive polarization curves. The results show that the successive polarization curves are the best choice for recovery; it took 35 min to reach full recovery of cell performance, compared to 4.5 hours of recovery with pure air at 0.5 A cm-2 and 110 ml min-1. However, the performance recovery at a current density of 0.2 A cm-2 and air flow 275 ml min-1 was done in 66 min, which is also a possible alternative. Additionally, two operation techniques are suggested and compared during 7 h of operation; air recovery and air depletion. The air recovery technique shows to be a better choice than the air depletion technique.

  • 17.
    Acevedo Gomez, Yasna
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lagergren, Carina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Performance Recovery after Contamination with Nitrogen Dioxide in a PEM Fuel Cell2020In: Molecules, ISSN 1431-5157, E-ISSN 1420-3049, Vol. 25, no 5, article id 1115Article in journal (Refereed)
    Abstract [en]

    While the market for fuel cell vehicles is increasing, these vehicles will still coexist with combustion engine vehicles on the roads and will be exposed to an environment with significant amounts of contaminants that will decrease the durability of the fuel cell. To investigate different recovery methods, in this study, a PEM fuel cell was contaminated with 100 ppm of NO2 at the cathode side. The possibility to recover the cell performance was studied by using different airflow rates, different current densities, and by subjecting the cell to successive polarization curves. The results show that the successive polarization curves are the best choice for recovery; it took 35 min to reach full recovery of cell performance, compared to 4.5 h of recovery with pure air at 0.5 A cm(-2) and 110 mL min(-1). However, the performance recovery at a current density of 0.2 A cm(-2) and air flow 275 mL min(-1) was done in 66 min, which is also a possible alternative. Additionally, two operation techniques were suggested and compared during 7 h of operation: air recovery and air depletion. The air recovery technique was shown to be a better choice than the air depletion technique.

  • 18. Adamus, Grazyna
    et al.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Höglund, Anders
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Kowalczuk, Marek
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    MALDI-TOF MS Reveals the Molecular Level Structures of Different Hydrophilic-Hydrophobic Polyether-esters2009In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 10, no 6, p. 1540-1546Article in journal (Refereed)
    Abstract [en]

    Multi- and triblock copolymers based on 1,5-dioxepan-2-one/epsilon-caprolactone (DXO/CL) were investigated by MALDI-TOF MS to determine the influence of copolymer composition and architecture on the molecular structures at the individual chain level. The copolymer compositions, average block lengths, and molecular weights were determined by H-1 and C-13 NMR and by SEC, respectively. The structures of polyether-ester oligomers (linear, cyclic) as well as the chemical structures of their end groups were established on the basis of their MALDI-TOF mass spectra. The mass spectrum of PDXO homopolymer was relatively simple, however, complex mass spectra were obtained in the case of multi- and triblock copolymers and the mass spectra clearly discerned the molecular level effect of copolymer composition and copolymer type.

  • 19.
    Adolfsson, Karin H.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Huang, Ping
    Department of Chemistry – Ångström Laboratory, Uppsala University, Box 523, Uppsala, 751 20, Sweden, Box 523.
    Golda-Cepa, Monika
    Faculty of Chemistry, Jagiellonian Universityul, Krakow, 30–387, Poland.
    Xu, Huan
    School of Materials Science and Physics, China University of Mining and Technology, Xuzhou, 221116, P. R. China.
    Kotarba, Andrzej
    Faculty of Chemistry, Jagiellonian Universityul, Krakow, 30–387, Poland.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Scavenging of DPPH by Persistent Free Radicals in Carbonized Particles2023In: Advanced Sustainable Systems, E-ISSN 2366-7486, Vol. 7, no 3, article id 2200425Article in journal (Refereed)
    Abstract [en]

    Persistent free radicals (PFR) in carbonized particles may play a role in degradation of environmental compounds. The influence of PFR is evaluated in various carbonized particles on their radical scavenging efficiency upon the common radical indicator 2-2-diphenyl-1-picrylhydrazyl (DPPH). Carbonized particles are derived by hydrothermal carbonization of glucose (C-W) or glucose and urea (NC-W) and ionothermal carbonization of glucose and urea ionic liquid (IL) (NC-IL). The carbonized materials contain OH/COOH, C=C, and C-O functionalities. The addition of urea introduces NH/NH2 functionalities. The content of polar surface groups is lower in IL-processed NC-IL. The scavenging ability, measured as DPPH UV–vis absorption decline, increases with concentration and time for all particles, while the efficiency changes are in the order of C-W > NC-W > NC-IL. Electron paramagnetic resonance analysis reveals similar radical concentration in all carbonized materials studied. The difference in efficiency is, thus, not directly related to the PFR concentration but rather to the type of PFR, surface functionalities and/or scavenging mechanism. According to the g-values, radicals in these particles are carbon-centered. The minor variation in g-values suggests interactions between the radicals and their environmental functional groups. This provides insights into the influence of PFR in carbonized materials on their radical scavenging efficiency.

  • 20.
    Adolfsson, Karin H.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Lin, Chia-feng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Microwave Assisted Hydrothermal Carbonization and Solid State Postmodification of Carbonized Polypropylene2018In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 6, no 8, p. 11105-11114Article in journal (Refereed)
    Abstract [en]

    Functional carbon materials produced through a hydrothermal treatment of waste products have gained interest. Particularly, the method is considered more facile and green compared to conventional decomposition methods. Here, we demonstrated an upcycling of polypropylene (PP) waste to carbon materials by a microwave assisted hydro thermal treatment. The solid product obtained from the hydrothermal treatment was analyzed by multiple techniques to reveal the structure and the influence of processing conditions on PP degradation and hydrothermal carbonization. Chemical analyses showed the presence of carbonaceous material independent of acid amount (20 and 30 mL), temperature (210 and 250 degrees C), and time (20-80 min). A complete transformation of PP content to amorphous carbon required 60 min at 250 degrees C. The mass yield of the solid product decreased as a function of harsher processing conditions. At the same time, thermogravimetric analysis illustrated products with increasing thermal stability and a larger amount of remaining residue at 600 degrees C. The solid products consisted of irregular fragments and sheet-like structures. A solid state microwave process in air atmosphere was performed on a product with incomplete carbonization. The modification resulted in a decreased C/O ratio, and TGA analysis in nitrogen showed high thermal stability and degree of carbonization as indicated by the remaining residue of 86.4% at 600 degrees C. The new insights provided on the hydrothermal carbonization, and postmodification in air atmosphere, can catalyze effective handling of plastic waste by enabling transformation of low quality waste into functional carbon materials.

  • 21.
    Adolfsson, Karin H.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Sjöberg, I.
    Höglund, O. V.
    Wattle, O.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    In Vivo Versus In Vitro Degradation of a 3D Printed Resorbable Device for Ligation of Vascular Tissue in Horses2021In: Macromolecular Bioscience, ISSN 1616-5187, E-ISSN 1616-5195, Vol. 21, no 10, article id 2100164Article in journal (Refereed)
    Abstract [en]

    A resorbable 3D printed polydioxanone (PDO) device is manufactured to facilitate ligation of vascular tissue during surgery. The device must provide sufficient mechanical performance throughout the healing period. Therefore, degradation and mechanical performance of the device are investigated as a function of in vivo and in vitro aging. During aging the PDO device released cyclic and linear water-soluble products. In vivo aging resulted in higher relative number of linear oligomers in comparison to in vitro aging. A major loss of mechanical performance is observed after only 10 days in vivo and the Young’s modulus (E) and tensile strength at break (σb) decreased by 28% and 54%, respectively. This is in contrast to in vitro aging, where no loss of mechanical properties is observed during the same period. The in vivo aged devices exhibit clear holes in the matrices after 28 days, while apparent cracks are observed first after 140 days in vitro. These results highlight the sensitivity of the degradation process of resorbable devices with regards to the interactions of the device with the surrounding environment (tissues) and demonstrate the importance of in vivo testing as compliment to in vitro testing before clinical use of devices.

  • 22.
    af Ugglas, Samuel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Waste diagnostic - A caste study of a company’s waste management2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This case study of the waste management at a pharmaceutical company investigates the current situation and possible improvements for future work in terms of amount of waste generated, treatment methods and economy. The scope of the project was to assess all current waste streams from the everyday activities and find potential areas for improvement. Chemical/solvent waste have not been investigated thoroughly because of the complexity to make changes within the manufacturing processes. Waste generated during demolition and construction by external contractors have been excluded since it is not a part of the business as usual.

    The company has set the goal to decrease greenhouse gas emissions by 20% and waste generated by 15% and to achieve these goals the waste diagnostic project have been initiated. Waste reports and guided tours at each department have been compiled to assess and map out all waste streams at the site. The waste management hierarchy has been used as a tool together with performance measurements to evaluate current situation and with examples from literature, other sites and industries recommendations have been made. The waste management hierarchy is a tool used to prioritize waste management to reach a circular economy, with landfill at the bottom and reduction/reuse at the top of the hierarchy the current status of a company can be assessed and also what areas that have to be improved in order to climb the hierarchy. The company shows a good environmental performance today and comply with internal standards, the waste metric scoring calculation results in a value of, , 464 which corresponds to energy recovery level of the waste management hierarchy.

    An ISO certificate ensures customers that a product or service meet the standards the customer have. There are ISO standards within many different areas and ISO 14001 applies to environmental management which the company is not certified with. The company comply with the internal standards but an ISO certificate would result in extra credibility. Some of the recommendations to the site includes a waste management communication program to engage employees, reuse of disposable pallets, drying of wastewater sludge and installation of paper shredder to reduce costs related to classified documents.

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  • 23.
    Agarwal, Ayush
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Experimental study of high-pressure fluidized bed gasification of biomass at pilot scale: A proof of concept2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Climate change is real. Rising world population and increasing energy demands are taking a toll on the planet. Moving towards a greener, cooler and sustainable future, there is a need for cleaner, efficient, and reliable sources of energy, and biomass is one of them. This thesis work performed at KTH Royal Institute of Technology attempts to contribute to this pressing need. High-pressure biomass gasification technology is an important process intensification step. However, it is not well investigated yet. This work attempts to understand the performance and pave the pathway for future studies.

    Experiments were performed using olivine, magnesite, and silica sand as bed material. Grot and birch were tested as fuel. The experiments were carried out in a 75 KWfuel bubbling fluidized bed gasifier at 20 bar, using Steam/Oxygen as a gasifying agent. Produced gas composition, tar production, and carbon conversion efficiency were examined. Olivine and magnesite showed good resistance against attrition and agglomeration. Stable bed temperature with no signs of defluidization or sintering were observed during the experiments. Silica sand cannot be used as a bed material with grot due to its high ash content. However, mild agglomeration was also observed with the birch feedstock. Carbon dioxide in the produced gas increased with increase in pressure, whereas, carbon monoxide decreased with increase in pressure. Olivine showed excellent reduction properties for tars lighter than naphthalene, whereas, magnesite performed best for overall tar reduction for grot. It was observed that fuel feeding is a big challenge for running operation at high pressure.

    These tests at 20 bar were an intermediate step to validate BFB biomass gasification at 40 bar. It would be interesting to study the changes in gas composition, tar, and char formation to evaluate the performance related to carbon conversion efficiency, produced gas composition, and tar production for different bed material at 40 bar.

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  • 24.
    Aglén, Lina
    KTH, School of Chemical Science and Engineering (CHE).
    Qualification of Low Value Fuels for Production of Syngas via the WoodRoll Process2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis project has, on behalf of Cortus Energy AB, investigated how to increase the

    suitability of so called low value fuels for use in the thermochemical conversion process WoodRoll®.

    The theoretical background of the report includes theory on pyrolysis, gasification and ash chemistry,

    as well as a description of WoodRoll® and a comparison between Woodroll® and more conventional

    technologies. A theoretical and an experimental trial have been conducted to investigate methods

    for potentially increasing the ash fusion temperatures of low value fuels. The theoretical study

    compared published articles on leaching and co-gasification. The experimental study was performed

    using thermogravimetric analysis and investigated if blending was a viable alternative for improving

    behavior. Three new types of industrial wastes were also tested.

    Both the theoretically investigated pretreatment methods and the blending were indicated to

    improve the behavior of low value fuels. When compared, blending was deemed to be economically

    favorable over the investigated pretreatment methods. The most economically favorable alternative

    is if two low value fuels with complementing characteristics can be successfully blended. Blending

    would also be easier to integrate with the current WoodRoll® process design and showed promise of

    high fuel flexibility. The behavior of the blends were influenced by their level of homogeneousness,

    a relationship of interest to investigate further in the future.

  • 25.
    Aguilar-Sanchez, Andrea
    et al.
    Stockholm Univ, Div Mat & Environm Chem, Frescativagen 8, S-10691 Stockholm, Sweden..
    Jalvo, Blanca
    Stockholm Univ, Div Mat & Environm Chem, Frescativagen 8, S-10691 Stockholm, Sweden..
    Mautner, Andreas
    Univ Vienna, Fac Chem, Inst Mat Chem & Res, Polymer & Composite Engn PaCE Grp, Wahringer Str 42, A-1090 Vienna, Austria..
    Nameer, Samer
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Pohler, Tiina
    VTT Tech Res Ctr Finland, Solut Nat Resources & Environm, POB 1000, FI-02044 Espoo, Finland..
    Tammelin, Tekla
    VTT Tech Res Ctr Finland, Solut Nat Resources & Environm, POB 1000, FI-02044 Espoo, Finland..
    Mathew, Aji P.
    Stockholm Univ, Div Mat & Environm Chem, Frescativagen 8, S-10691 Stockholm, Sweden..
    Waterborne nanocellulose coatings for improving the antifouling and antibacterial properties of polyethersulfone membranes2021In: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 620, article id 118842Article in journal (Refereed)
    Abstract [en]

    This article presents a waterborne nanocellulose coating process to change the surface characteristics and mitigate fouling of commercially available polyethersulfone (PES) microfiltration membranes. An extensive comparative study between nanoporous and nano-textured layers composed of cellulose nanocrystals (CNC) or TEMPO-oxidized cellulose nanofibrils (T-CNF), which were coated on the PES membrane by taking advantage of the electrostatic interactions between the PES substrate, a polyallylamine hydrochloride (PAHC1) anchoring layer, and the nanocellulose functional layer. Coated PES membranes exhibited decreased surface roughness and pore sizes as well as rejection of compounds with a M-w above 150 kDa, while the water permeability and mechanical properties of remained largely unaffected. The coatings improved the wettability as confirmed by a reduction of the contact angle by up to 52% and exhibited a higher negative surface charge compared to the uncoated membranes over a pH range of 4-8. A significant reduction in organic fouling was observed for the coated membranes demonstrated by bovine serum albumin (BSA) adsorption studies on T-CNF and CNC surfaces using Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), UV-vis spectroscopy and FTIR mapping after exposing the membranes to dynamic adsorption of BSA. The T-CNF coating exhibited effective antibacterial action against Escherichia coli (E. coli) attributed to the pH reduction effect induced by the carboxyl groups; while CNC coatings did not show this property. This work demonstrates a simple, green, and easy-to-scale layer-by-layer coating process to tune the membrane rejection and to improve antifouling and antibacterial properties of commercially available membranes.

  • 26.
    Aguilera Costa, Joakim
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Uppgradering och identifiering av cellulosa och hemicellulosa i restströmmar från jordbruk och skogsindustri2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    By-products are in focus for further processing. Residues from agriculture and forest industry contain a large amount of fiber, and this work investigates the qualitative properties of residues and whether there is potential for using them in the cellulose industry.

    By-products collected were wheat straw, rapeseed straw, wheat bran, betfor, silage, branches, primary sludge, sawdust and fiber rejects. A literature study was conducted around each by-product to get a better understanding of what they consist of and how they occur.

    By extracting holocellulose from the by-products, the qualitative properties of the fibers were analyzed. For the slightest change in the shape and dimensions of fibers, a maceration method was used to extract holocellulose from the by-products.

    Methods used to analyze the qualitative properties of the by-products were viscosity, titrations and gravimetric analyzes. With these methods, mass exchanges, ash levels, mass viscosities, peracetic acid and hydrogen peroxide levels could be determined for the extracted holocellulose masses.

    To investigate whether the extracted holocellulose masses can be used in the cellulosic industry, two types of processes were tested. One was aerogel production and the other a compression mold to produce high strength biocomposites.

    It was found that the fiber rejects yielded the greatest holocellulose exchange compared to the other residues. The analyzes gave the result that sawdust had the fibers with the highest degree of polymerization while wheat bran and betfor had the fibers with the lowest degree of polymerization. The dissociation of the holocellulose mass could not be performed because the test sample had either a too high mass viscosity or a too high a proportion of hemicellulose which prevents the solvent from dissolving the fibers. Compression molding of the holocellulose mass from wheat straw was successful as it was possible to make the soft pulp a lot more rigid. Compression molding of the holocellulose masses may be an alternative for producing additive manufacturing materials (3D printing).

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  • 27.
    Ahlawat, Paramvir
    KTH, School of Chemical Science and Engineering (CHE).
    Modellering och implementering av simultan dubbel gradient kromatografi2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Polypeptides are becoming an important component of the antibiotic therapeutics. The production demand of therapeutic polypeptides is increasing and there is a significant interest in developing more efficient production processes. In pharmaceutical industries, polypeptides are produced as a crude mixture. Reverse phase high performance liquid chromatography (RP HPLC) is used as a typical separation technique to purify the target polypeptide from other impurities. Currently organic modifier gradients are used to elute product peptides separately from impurities. In this work, we add a second, simultaneous counter-ion gradient, in the hope of increasing separation performance and call it double gradient reverse phase chromatography. A general procedure of the model-based optimization of a polypeptide crude mixture purification process was followed to evaluate the effects of the double gradients on industrial chromatographic process. The target polypeptide elution profile was modeled with a bi-Langmuir adsorption equilibrium isotherm. The isotherm parameters of the target polypeptide were estimated by the inverse method. The model parameters of the impurities were regressed from experimental data. The variations of the isotherm parameters with the modifier concentration and counter-ion concentration were taken into account of the adsorption model. After model calibration and validation by comparison with suitable experimental data, Pareto optimization of the process were carried out to analyze the differences between single gradient chromatography and double gradient chromatography. It was observed that the additional linear gradient of counter-ion concentration did not improve the separation process. Conclusively we were able to demonstrate the concept of double gradient reverse phase chromatography within limited time and possible least experimental efforts.

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  • 28.
    Ahlberg Tidblad, Annika
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Surface analysis with ESCA and GD-OES of the film formed by cathodic reduction of chromate1991In: Electrochimica Acta, Vol. 36, no 10, p. 1605-1610Article in journal (Refereed)
    Abstract [en]

    In the chlorate process, a small addition of chromate to the electrolyte results in the formation of a cathode film, which inhibits the reduction of the intermediate hypochlorite ions. To enable surface characterization of the chromium film, it was grown by cathodic reduction onto gold and platinum substrates in hydroxide and chlorate solution. Surface analyses of this film by ESCA and GD-OES indicate that it has a distinct and constant chemical composition during growth given by the formula Cr(OH)3·xH2O. The film is thin, less than 50 Å on platinum and 80 Å on gold. It exhibits poor conductivity and covers the entire cathode surface. © 1991.

  • 29.
    Ahlinder, Astrid
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology. KTH Royal Institute of Technology.
    Degradable copolymers in additive manufacturing: controlled fabrication of pliable scaffolds2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In tissue engineering, the production of well-defined scaffolds with a porous architecture from degradable polymers is of great interest. Detailed designs have become feasible through the development of additive manufacturing. A small nozzle size is needed to obtain detailed scaffold structures, and careful control of the rheological properties is therefore required during production. A lower viscosity of the melt allows for easier printability, but a high molar mass is required to produce scaffolds that can retain mechanical properties over the time needed for tissue regeneration. An additional challenge of using degradable polymers with high molar mass in any melt-based processing is that thermal degradation can reduce the molar mass during the production stage. To utilise medical grade degradable polymers whilst limiting the thermal degradation a rheological analysis of the most commonly used commercial medical-grade degradable synthetic polymers was performed. Their rheological behaviours aided in setting process parameters for two different melt-based additive manufacturing routes. The variation in thermal degradation in the two routes was assessed, and the parameters were adjusted to minimise it.

    A nondegradative additive manufacturing method was designed, and knowledge regarding printability was developed based on rheological analysis and polymer characterisation methods. This knowledge was applied to the copolymer poly(e-caprolactone-co-p-dioxanone) developed within the group to fabricate pliable scaffolds for tissue engineering with an increased rate of hydrolysis in comparison to poly(e-caprolactone). In addition to the selection of the polymer and process parameters, the mechanical properties were also controlled through the structural design. Poly(e-caprolactone) was used as a model material to show how the mechanical properties of scaffolds could be controlled based on the design solely. The results showed that the stiffness could be reduced by more than a factor of 10 through tuning of the design, resulting in soft pliable scaffold structures.

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  • 30.
    Ahlström, Leon
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Evaluation of Woodmer/plastic composites2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Plastics provide incredible opportunities in the form of great versatility for material usage. However, this comes at the cost of environmental issues as they accumulate in the environment. Therefore a compromise between sustainability and continued plastic usage is to use biomass as a filler material in plastic composites instead of virgin plastics. This would in turn reduce the amount of plastic and increase the usage of renewable raw materials. Of course the mechanical and thermal properties must also be of acceptable quality for material applications and preferably even offer some form of improvement to the preexisting material. One potential biomass filler material is Woodmer, a LCC (lignin carbohydrate complex) produced by Ecohelix. The viability of Woodmer as a thermoplastic composite material was analysed and compared to virgin thermoplastics. Three different plastics were used as basis for the composites and these plastics were Acrylonitrile-butadiene-styrene (ABS), polylactic acid (PLA) and low density polyethylene (LDPE).

    The results show that it is possible to create homogenous Woodmer/thermoplastic composites. As for the thermal properties, while the UL 94 provided no flame classification on the materials some positive effects were observed in TGA and the results from the DSC were similar to the virgin plastics. The tensile test on the other hand showed that the mechanical properties were negatively affected by increasing Woodmer additions but the effect varied substantially between the different plastics as LDPE was the least affected and PLA the most affected. Future research should focus on making the materials through twin screw extrusion as there were unfortunately issues with the mixing from single screw extruders. Further research regarding the materials morphology, solubility and so forth are also required to see if the composites are suitable materials or if there are any unforeseen issues.

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  • 31.
    Ahlén Norberg, Evelina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Influence of current harmonics on the degradation of the catalyst coated membrane in PEMFC2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The marine shipping industry is dominated by fossil fuel driven propulsion. Electrification of marine vessels is one of the main strategies to enable emission-free propulsion. Hydrogen is an excellent energy carrier to meet the power demand of a marine vessel. Proton exchange membrane fuel cells (PEMFC) is a commercially available alternative for converting hydrogen into electricity. However, durability issues of the PEMFC is a constraint with the technology which limits technical lifetime. Research around ripple currents impact on degradation of PEMFC is scarce and the reported results are ambiguous and lack clear correlation between the effects of the ripple current on the lifetime of a PEMFC.

    This master thesis evaluates the impact on degradation of a single cell PEMFC by imposing a sinusoidal (70 Hz, 50 % amplitude) AC ripple to a dynamic load cycle. The dynamic load cycle is designed to simulate typical operating conditions of a marine vessel. Constant load cycling at 0.4 A/cm2 with the same ripple characteristics was also conducted to verify the dynamic load cycling impact on the performance losses of the PEMFC.

    The in-situ characterization showed performance losses both during the dynamic and constant load cycling, for the ripple current and reference tests. To conclude, no significant effects on degradation by the sinusoidal ripple current of 70 Hz and 50% amplitude is found when applied to a single cell PEMFC despite of performance losses for all cases.

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  • 32.
    Ahlén Norberg, Evelina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Metodutveckling för bestämning av vattenhalt i presspan2020Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the production of new transformers, the moisture from the air is adsorbed in the solid insulation and affects the insulation capacity. Therefore, the transformer undergoes a drying process before filling it with oil. Water content in the solid insulation is measured quantitatively by Karl Fischer titration. Karl Fischer titration is widely used for determining water content in products in the industry and is a proven method that has been used for many years. The manual method for determining moisture content in pressboard is time consuming due to long sample preparation with thermal extraction with methanol. An automated method for water content determination in pressboard has been developed by KF oven extraction.

    A quantitative analysis of the water content of pressboard by KF coulometry through oven extraction was compared with KF coulometry through methanol extraction. The purpose of this study was to investigate the possibility to develop a faster and simpler measurement method for the moisture content in High-Density Casein Laminated Pressboard (HDLC) and High-Density Polyester Laminated Pressboard (HDLP) by implementing oven extraction for KF coulometry. The initial step was to investigate and determine methods for sample preparation and operating parameters (oven temperature, carrier-gas flow and extraction time). Determined operating parameters were oven temperature 170 degrees Celsius, carrier gas flow of 50 ml/min and extraction time of 600 seconds. The result of investigation of different sample preparations indicated that sample selection with gouge or chisel did not meet the demands to replace sample selection by drilling.

    Validation of the method was carried out with a certified solid standard of known moisture content (1%) from Aquastar (certified in an ISO/IEC 17025 accredited testing laboratory). The measured concentration was lower than the expected concentration. A calibration model was established from the standard with a correlation of 0.9952 indicating the calibration model showed good linearity. The trueness of the measurement method has been evaluated according to ISO 5725-4 confirming the trueness of the method was not approved.

    The result of the comparison of methanol extraction and oven extraction indicated that the method was not as good as methanol extraction due to lower results of water content in the comparison samples. The method is applicable under the terms of the error is identified and eliminated. Further confirmatory experiments are needed to implement the method.

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  • 33.
    Ahmad, Waqar
    et al.
    KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    Zheng, Li-Rong
    KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK. KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    Weerasekera, Roshan
    KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    Chen, Qiang
    KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK. KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    Weldezion, Awet Yemane
    KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    Tenhunen, Hannu
    KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK. KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    Power Integrity Optimization of 3D Chips Stacked Through TSVs2009In: ELECTRICAL PERFORMANCE OF ELECTRONIC PACKAGING AND SYSTEMS, NEW YORK: IEEE , 2009, p. 105-108Conference paper (Refereed)
    Abstract [en]

    On-chip power distribution network model for simultaneous switching of 3D ICs stacked through TSVs to choose TSV pattern, maximum number of chips in a stack and location of the decoupling capacitor for early design trade-offs.

  • 34.
    Ahmadi, Mozhgan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Brage, Claes O.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Sjöström, Krister
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Engvall, Klas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Knoef, H.
    Van De Beld, B.
    Development of an on-line tar measurement method based on photo ionization technique2011In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 176, no 1, p. 250-252Article in journal (Refereed)
    Abstract [en]

    This paper presents work in progress for development of an on-line method based on PID (Photo Ionization Detector) for quantitative measurement of tar from biomass gasification. To calibrate the method the PID signals are compared to quantitative data of individual tar compounds obtained by an established reference method. The measured response factors for the model tar compounds demonstrated very good linearity. The PID approach was tested on-line with real producer gases from an atmospheric fluidized bed gasifier operated at 800-900 °C. The results suggest that PID can be used for continuous on-line tar measurement of product gases from biomass gasification.

  • 35.
    Ahmadi, Mozhgan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Knoef, Harrie
    Van De Beld, Bert
    Liliedahl, Truls
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Engvall, Klaus
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Development of a PID based on-line tar measurement method: Proof of concept2013In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 113, p. 113-121Article in journal (Refereed)
    Abstract [en]

    In this study, a proof of concept was conducted for an on-line tar analyzer based on photo ionization detection (PID). Tar model compounds (naphthalene, acenaphthene, acenaphthylene, fluorene, indane and indene) were used for the initial investigation of the analysis method. It was found that the analysis method has a high sensitivity and a linear behavior was observed between the PID response and the tar concentration over a wide concentration span. The on-line tar analysis method was successfully validated against the solid phase adsorption (SPA) method using a real producer gas.

  • 36.
    Ahmed, Ilwad
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Omställning från mesofil till termofil rötning på Hammarby Sjöstadsverket2022Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the future, the load on the Henriksdal water treatment plant will double, which means an increase serving from about 800,000 people to 1.6 million people. The hygiene requirements for sludge will also become stricter. The digestion process in Henriksdal Wastewater treatment plant is currently mesophilic (37 °C) but the plans is to convert the process to thermophilic (55 °C). This conversion was studied in detail at the Hammarby Sjöstadsverk pilot plant. Prior to the conversion, a trial with mesophilic operation took place. The results of this trial were used as a reference. 

    The experiment took place with a five cubic meter reactor and the temperature was gradually increased from 37 °C to 55 °C with a slightly larger increase at the beginning. The experiment took place over a period of three weeks. Parameters studied were total solids, volatile solids, volatile fatty acids, alkalinity, pH, ammonium nitrogen and gas composition (𝐶𝐻4, 𝐶𝑂2, 𝐻2𝑆). 

    The conversion process was relatively stable during the first three days. When the temperature reached 46 °C, methane-forming microorganisms collapsed. This was detected by the increasing VFA concentration to 2736 [mg/l], pH dropped from 7.1 to 6.7, and methane exchange deteriorated with a minimum of 37 %. The carbon dioxide content increased as a result of the increase in temperature and the decrease in pH. Process alkalinity was relatively strong during the conversion but decreased from 2210 [mg/l] to a minimum of 1120 [mg/l]. This is because of the decomposition of VFA consumes the alkalinity. During the process, the organic loading rate (OLR) varied between 0 and 3.84 [kgVS/ m3, d] and the organic destruction efficiency was between -47.5% and 71.2%. This is due to the fact that the sludge quality (TS and VS) and flows varied greatly during the conversion. The FAN concentration and hydrogen sulfide concentration increased during the conversion but never reached the toxic levels reported in the literature. The process started to stabilize one week after the temperature reached 55.0 °C and the conversion was successful. 

    Käppala wastewater treatment plant experimented a conversion at its pilot plant. The conversion strategy was different compared to the experiment at Hammarby Sjöstadsverket's pilot plant. Käppala reduced its OLR to 1.5 [kgVS/ m3, d] before the conversion but gradually increased it later in the experiment. Stop of feeding also occurred during the Käppala conversion. Problems encountered during the Käppala conversion were huge increase in VFA, low biogas production and poor biogas composition. Because of this, it is recommended to convert the Henriksdal digester using the same strategy as the trial at the Hammarby Sjöstadsverk pilot plant. 

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  • 37.
    Ahmed, Safiya
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Carlsson, Jesper
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Blomberg, Jenny
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Wiberg, Filip
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Biokol av avfallsfraktioner från IKEA:s möbeltillverkning2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I dagens samhälle genereras en stor mängd avfall, där stora delar av avfallen förbränns vilket inte är gynnsamt för vare sig miljön eller klimatet. Därför finns det idag ett stort behov av klimatsmarta metoder där avfallen kan användas till att producera produkter som kan motverka klimatförändringar. Största delen av avfallen som genereras kommer från större företag som till exempel IKEA och de är i ständigt behov av nya metoder för att kunna använda sina avfall till klimatsmarta resurser. Att producera biokol av avfallen är en sådan klimatsmart metod, där biokolet är en hållbar produkt som både motverkar klimatförändringar och andra miljöproblem såsom övergödning. I denna rapport undersöktes två avfallsfraktioner från IKEA, vilka var Dust2k och Hogger. Det som undersöktes var hur lämpliga avfallsfraktionerna från IKEA är för produktion av biokol som skulle kunna appliceras i jordbruket samt hur denna lämplighet påverkas av avfallsfraktion och processförhållanden som används under pyrolysen.

    För att besvara frågeställningarna utfördes pyrolys på avfallsfraktionerna vid pyrolystemperaturerna 550℃ och 750℃, vilket gav fyra olika prover av biokol. Dessa prov analyserades med ett antal analysmetoder för att avgöra biokolets lämplighet som jordförbättrare och för att motverka klimatförändringar. De analyser som utfördes var elementaranalys, pH-mätning, termogravimetrisk analys (TGA), Brunauer-Emmet-Teller (BET) och svepelektronmikroskopi (SEM). Från pyrolysen och TGA kunde utbytet bestämmas, vilket uppgick till över 20% för samtliga prov. Elementaranalysen visade att biokol producerat av Hogger vid 900°C uppfyllde de EBC-krav som analyserades. Genom att mäta pH på avfallsfraktionerna samt biokolen gick det att se att pH höjdes under pyrolysen. Från BET och SEM erhölls information om porositet, ledningsförmåga och ytarea. Porositeten ökade med temperaturen och ledningsförmågan var högre för biokolet än biomassan. Ytarean låg mellan 347,2 m2/g och 422,8 m2/g och porvolymen mellan 0,173 cm3/g och 0,205 cm3/g. Det erhölls bäst egenskaper för avfallsfraktionen Hogger samt pyrolystemperaturen 750℃, vilket gjorde att slutsatsen att produktion av biokol från Hogger vid 750℃ lämpar sig bäst för användning som jordförbättrare kunde dras.

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  • 38.
    Aisling, Lynch
    et al.
    Univ Limerick, Synth & Solid State Pharmaceut Ctr, Mat & Surface Sci Inst, Dept Chem & Environm Sci, Limerick, Ireland..
    Rasmuson, Åke C.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering. Synthesis and Solid State Pharmaceutical Centre, Department of Chemical and Environmental Science, University of Limerick, Limerick, Ireland.
    Crystal Growth of Single Salicylamide Crystals2019In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 19, no 12, p. 7230-7239Article in journal (Refereed)
    Abstract [en]

    Growth of single salicylamide crystals was investigated in a nonstirred growth cuvette and on a rotating disk. In the growth cuvette the crystal growth rates were measured for both primary nucleated crystals and seed crystals manually inserted into the cuvette. In the rotating disk experiments multiple seed crystals were attached to a disk that was rotated in a supersaturated solution. The crystal growth rates in the length and width direction were precisely measured in situ for each individual crystal, and growth rates were also extracted for a specific crystal facet, that is, (200). In all cases, the growth rate was considerably faster in the rotating disk experiments, shown to be governed by surface integration. Solvent was found to impact the growth rates of the crystal facets in part by creating different surface features. The influence of the supersaturation on the crystal growth rate depended on the solvent; in general, an increasing trend was observed. At relatively low supersaturations, it was discovered that the growth process will focus on repairing morphological defects. Within the range of experimental conditions, the growth kinetics were strongly affected by the temperature as was further indicated by the relatively high activation energy values obtained. The crystal seed quality was found to have a substantial impact on the growth rate, with rougher crystals leading to quicker growth. A wide growth rate dispersion was obtained for both crystal growth methods, found to be reduced by using seed crystals with high quality, lower supersaturations, and also within certain solvents.

  • 39.
    Ajpi Condori, Cesario
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry. UMSA-University.
    Hybrid materials for lithium-ion batteries2022Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Lithium‐ion batteries are the most important power source for electronic devices as electronics, storage and the different electric vehicles. The research and development of new materials for different applications has increased, especially in the development of materials with better electrochemical properties (Specific capacity, rate capability, high energy density and cyclability). Inorganic materials such as LiFePO4, LiMn2O4 and organic materials such as Li4C6O6, quinones and anthraquinones, polyaniline (PANI) and others have been extensively studied. Improvement of the electrochemical properties involve different aspects as: control in the particle size of the materials, doping with other elements and the combination of the different properties of the organic an inorganic materials. The development of hybrids materials with improved electrochemical properties need a combination between of inorganic and organic structures. This type of hybrids materials are a very attractive option for the development of advanced materials. For the design of this type of hybrid materials it is necessary to form interactions between the inorganic and organic part (supramolecular chemistry). This opens up for using an immense amount of organic materials such as conductive polymers and PANI (Polyaniline) are attractive alternatives in the development of hybrid materials due to their excellent electronic conductivity. Other attractive types of hybrid materials are compounds based on metal-organic frameworks (MOF), coordination polymers (CP) and coordination networks (CN).

    This thesis work is focused in the synthesis, structural characterization and electrochemical characterization of two groups of hybrid materials: 

    1) LiFePO4-PANI synthetized by different methods.

    2) Metal-organic compounds M-BDC-DMF with M=Ni2+, Fe2+, C8H4O2=Terephthalate=BDC=Benzene dicarboxylate, DMF=N,N-dimethylformamide.

    The materials were synthesized by chemical oxidation methods combined with thermal treatment (LiFePO4-PANI-Li hybrid powder) and by solvothermal methods (M-BDC-DMF). The materials were characterized by SCXRD, PXRD, FTIR, SEM and electrochemical methods and the electrochemical characterization was carried out using CV, EIS and galvanostatics methods. 

    The specific capacities of PANI was 95 mAh/g, of LiFePO4 was 120 mAh/g and of LiFePO4-PANI was 145 mAh/g at 0.1C. At 2C the capacity of LiFePO4 was 70 mAh/g and LiFePO4-PANI was 100 mAh/g. The specific capacities of Ni3(C8H4O4)3(C3H7NO)4 is ~50 mAh/g and Fe-BDC-DMF was ~175 mAh/g. 

    The work has shown that PANI can improve the performance of LFP also at higher discharges rates. For M-BDC-DMF stability seems to be an issue which should be studied more in the future.

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  • 40.
    Akan, Rabia
    KTH, School of Chemical Science and Engineering (CHE).
    Oorganiska-organiska nanopartikelbaserade supramolekylära strukturer för biomedicinska applikationer2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The possibility to create a multifunctional nanoparticle system via supramolecular chemistry approach with ability to simultaneously target, deliver and diagnose was investigated. Superparamagnetic iron oxide nanoparticles were synthesized by co-precipitation method and surface modified with the cyclic oligosaccharide carboxymethyl-β-cyclodextrin by three different routes. The different routes involved one, two or three reaction steps in order to reach to the final oligosaccharide functionalized nanoparticles. Esterification was performed using the intrinsic hydroxyl functionality of the nanoparticle surfaces or amine functionality was introduced prior to amidization. Further, a polymeric coating was created by incorporation of folic acid functionalized Pluronic® L-35 into carboxymethyl-β-cyclodextrin. The resulting nanoparticle based supramolecular systems were characterized by TEM, TGA, FT-IR, DLS and zeta potential techniques.

     

    The colloidal stabilities of the supramolecular nanoparticle systems were investigated in phosphate buffered saline with pH 7.4 representing body conditions. It was found that a three-step functionalization of iron oxide nanoparticles with citric acid, hexamethylenediamine and finally carboxymethyl-β-cyclodextrin resulted in the most stable ferrofluids. The average size of the resulting carboxymethyl-β-cyclodextrin functionalized nanoparticles was 25 nm prior to, and 50 nm after inclusion of folic acid functionalized Pluronic. The amount of grafted carboxymethyl-β-cyclodextrin on the nanoparticles surfaces was 25 weight %. Thus, the resulting stable ferrofluid creates an efficient platform with potential of multiple uses in biomedicine. This nanoparticle based supramolecular system combines the properties of magnetic targeting and MRI contrast enhancement due to the superparamagnetic iron oxide nanoparticle core, drug delivery of hydrophobic drugs due to the polymer capsule and selective targeting towards tumour cells due to the folic acid.

  • 41.
    Akbarkermani, Mohammadreza
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery. Chemical Engineering Department, Istanbul Technical University, 34469, Maslak, Istanbul, Turkey.
    Genceli Güner, Fatma Elif
    Chemical Engineering Department, Istanbul Technical University, 34469, Maslak, Istanbul, Turkey; Polar Research Center (PolReC), Istanbul Technical University, 34469, Maslak, Istanbul, Turkey; Nanotechnology Research and Application Center (ITUNano), Istanbul Technical University, 34469, Istanbul, Turkey.
    Eutectic freeze crystallization in the boric acid–water system2023In: Chemické zvesti, ISSN 0366-6352, E-ISSN 1336-9075, Vol. 77, no 10, p. 5881-5891Article in journal (Refereed)
    Abstract [en]

    Boron compounds are widely used in various industries. Current high rates of boron production/usage generate significant wastes. As an ecologically friendly technology, eutectic freeze crystallization (EFC) has the potential to treat boron wastewater ponds for mineral recovery; however, its feasibility has not been examined before. Here, we determined the eutectic point of boric acid (a major boron compound)-water system to be -0.79 °C and 2.5 ± 0.05 wt%. At the eutectic point, ice and boric acid crystals were isolated from the aqueous solution. The nucleation rate and growth rate of boric acid were considered, as well as the boron content in ice crystals. Our results show that it is feasible to separate boric acid and water from boron waste streams by EFC.

  • 42.
    Akhand, Victoria
    KTH, School of Chemical Science and Engineering (CHE).
    Mass Balance Model of Impurities for the WoodRoll Process2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The depletion time for fossil fuels calculated from 2009 is 35 years for oil, 37 years for gas

    and 107 years for coal. Hence, it has become essential to reduce the dependence on fossil

    fuels by switching over to renewable resources. This in turn will also help in combating the

    negative effects on the environment like global warming. Thermochemical processes such as

    pyrolysis and gasification of biomass are considered the most efficient technology for

    converting biomass to useful energy carriers. Cortus Energy AB is a Swedish company that

    has developed a patented gasification technology called WoodRoll

    ® for gasification of fuels derived from biomass. However, ash in a thermochemical conversion process can cause

    corrosion, sintering, slag and poisoning of catalysts, which leads to operational problems. In

    addition, heavy metals such as Zn, Pb and Cd are environmentally problematic. These metals

    contribute to environmental pollution by contaminating the soil, which in turn can harm

    humans and the ecosystem via the food chain. The undesired elements should therefore be

    identified to minimize their impact on the overall thermochemical process and to reduce the

    emission of these harmful substances.

    The objective of this master thesis project, on behalf of Cortus Energy AB, was to investigate

    possible key numbers that can be used to describe and predict how the ash behaves in their

    patented WoodRoll® process. The key numbers that have been identified are empirically

    developed based on experience of coal combustion. These key numbers are regularly used for

    fuel derived from biomass by companies specializing in analyzing, although knowledge about

    whether they can actually be used on biomass is limited. In order to ensure that the use of

    these for biomass is correct, they must be experimentally verified in the future. In addition, a

    theoretical investigation is conducted to study which species can form and in what phase this

    occurs. The investigation reveals that there are no clear trends for how the inorganic elements

    behave since contradicting results from different studies have been reported. Formation of

    species and their phase depends on several parameters such as temperature, heating rate,

    particle size, volatility, quantity and interaction between the elements in the biomass. The

    thesis project ends with a mass balance model on selected inorganic elements for wood

    residues, as well as for bark. The model could be a tool for Cortus Energy AB to identify

    approximately how much of each element is present in each stream in the WoodRoll® process.

    The models are verified with analysis results. Inorganic elements that affect the

    overall process and its equipment have been selected for modelling. The volume percent of

    H2, CO, CO2 and CH4 in the models agree well with the values obtained by Cortus Energy

    AB. This shows that the thermodynamic equilibrium calculations performed are reasonable.

  • 43.
    Akhlaghi, Lina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Potentialen hos hydrokol från avloppsslam som jordförbättringsmedel2022Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Margretelund's treatment plant in Åkersberga, like other Swedish sewage treatment plants, faces new challenges in connection with the adaptation to a more sustainable and circular society. In order to contribute to a good local environment with few transports and minimized odors, achieve a high degree of phosphorus recovery, and reduce organic and inorganic pollutants in the sludge, Roslagsvatten, in collaboration with the IVL Swedish Environmental Institute, will evaluate C-Green's OxyPower HTC-technology. 

    The HTC-technology is hydrothermal carbonization (HTC) combined with wet oxidation of HTC-water. The wet sludge is taken care of at the treatment plant and converted into a fast carbon-enriched product called HTC-biochar or hydrochar. The HTC-process involves heating the wet sludge (180–260°C) under high pressure and oxygen-free conditions with water present. The hydrochar that is formed can be upgraded to fuel, soil improver or activated carbon. 

    In this work, the potential of using hydrochar as a soil improver is studied by examining the biochar's physical and chemical properties. Hydrochar was compared with biochar from pyrolysis, which is also a charring process of biomass at high temperatures (300–650 °C) under oxygen-free conditions but without the presence of water. 

    Based on the results of published studies, hydrochar has the potential to replace or supplement mineral fertilizers. Hydrochar improves soil fertility and productivity by e.g. increase overall plant growth, improve nutrient mineralization and phosphorus availability, and provide a slow release of nutrients. 

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  • 44.
    Akhlaghi, Shahin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Degradation of acrylonitrile butadiene rubber and fluoroelastomers in rapeseed biodiesel and hydrogenated vegetable oil2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Biodiesel and hydrotreated vegetable oil (HVO) are currently viewed by the transportation sector as the most viable alternative fuels to replace petroleum-based fuels. The use of biodiesel has, however, been limited by the deteriorative effect of biodiesel on rubber parts in automobile fuel systems. This work therefore aimed at investigating the degradation of acrylonitrile butadiene rubber (NBR) and fluoroelastomers (FKM) on exposure to biodiesel and HVO at different temperatures and oxygen concentrations in an automated ageing equipment and a high-pressure autoclave. The oxidation of biodiesel at 80 °C was promoted by an increase in the oxygen partial pressure, resulting in the formation of larger amounts of hydroperoxides and acids in the fuel. The fatty acid methyl esters of the biodiesel oxidized less at 150 °C on autoclave aging, because the termination reactions between alkyl and alkylperoxyl radicals dominated over the initiation reactions. HVO consists of saturated hydrocarbons, and remained intact during the exposure. The NBR absorbed a large amount of biodiesel due to fuel-driven internal cavitation in the rubber, and the uptake increased with increasing oxygen partial pressure due to the increase in concentration of oxidation products of the biodiesel. The absence of a tan δ peak (dynamical mechanical measurements) of the bound rubber and the appearance of carbon black particles devoid of rubber suggested that the cavitation was caused by the detachment of bound rubber from particle surfaces. A significant decrease in the strain-at-break and in the Payne-effect amplitude of NBR exposed to biodiesel was explained as being due to the damage caused by biodiesel to the rubber-carbon-black network. During the high-temperature autoclave ageing, the NBR swelled less in biodiesel, and showed a small decrease in the strain-at-break due to the cleavage of rubber chains. The degradation of NBR in the absence of carbon black was due only to biodiesel-promoted oxidative crosslinking. The zinc cations released by the dissolution of zinc oxide particles in biodiesel promoted reduction reactions in the acrylonitrile part of the NBR. Heat-treated star-shaped ZnO particles dissolved more slowly in biodiesel than the commercial ZnO nanoparticles due to the elimination of inter-particle porosity by heat treatment. The fuel sorption was hindered in HVO-exposed NBR by the steric constraints of the bulky HVO molecules. The extensibility of NBR decreased only slightly after exposure to HVO, due to the migration of plasticizer from the rubber. The bisphenol-cured FKM co- and terpolymer swelled more than the peroxide-cured GFLT-type FKM in biodiesel due to the chain cleavage caused by the attack of biodiesel on the double bonds formed during the bisphenol curing. The FKM rubbers absorbed biodiesel faster, and to a greater extent, with increasing oxygen concentration. It is suggested that the extensive biodiesel uptake and the decrease in the strain-at-break and Young’s modulus of the FKM terpolymer was due to dehydrofluorination of the rubber by the coordination complexes of biodiesel and magnesium oxide and calcium hydroxide particles. An increase in the CH2-concentration of the extracted FKM rubbers suggested that biodiesel was grafted onto the FKM at the unsaturated sites resulting from dehydrofluorination.

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  • 45.
    Akhlaghi, Shahin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Amir Masoud, Pourrahimi
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Christian, Sjöstedt
    Martin, Bellander
    Mikael S., Hedenqvist
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ulf W., Gedde
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Degradation of fluoroelastomers in rapeseed biodiesel at different oxygen concentrations2017In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 136, p. 10-19Article in journal (Refereed)
    Abstract [en]

    The degradation of fluoroelastomers (FKM) based on different monomers, additives and curing systems was studied after exposure to rapeseed biodiesel at 100 °C and different oxygen partial pressures. The sorption of fuel in the carbon black-filled FKM terpolymer was promoted by the fuel-driven cavitation in the rubber. The bisphenol-cured rubbers swelled more in biodiesel than the peroxide-cured FKM, presumably due to the chain cleavage caused by the attack of biodiesel on the double bonds formed during the bisphenol curing. With any of the selected types of monomer, the FKM rubbers absorbed biodiesel faster and to a greater extent with increasing oxygen partial pressure due to the increase in concentration of the oxidation products of biodiesel. Water-assisted complexation of biodiesel on magnesium oxide and calcium hydroxide particles led to dehydrofluorination of FKM, resulting in an extensive fuel uptake and a decrease in the strain-at-break and the Young's modulus of the rubbers. An increase in the CH2-concentration determined by infrared spectroscopy, and the appearance of biodiesel flakes in scanning electron micrographs of the extracted rubbers, were explained as being due to the presence of insoluble biodiesel grafted onto FKM on the unsaturated sites resulting from dehydrofluorination. The extensibility of the GFLT-type FKM was the least affected on exposure to biodiesel because this rubber contained less unsaturation and metal oxide/hydroxide particles.

  • 46.
    Akhlaghi, Shahin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pourrahimi, A. M.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Christian, Sjöstedt
    Martin, Bellander
    Mikael S., Hedenqvist
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ulf W., Gedde
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Effects of ageing conditions on degradation of acrylonitrile butadiene rubber filled with heat-treated ZnO star-shaped particles in rapeseed biodiesel2017In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321Article in journal (Refereed)
    Abstract [en]

    The degradation of acrylonitrile butadiene rubber (NBR) after exposure to biodiesel at different oxygen partial pressures in an automated ageing equipment at 80 °C, and in a high-pressure autoclave at 150 °C was studied. The oxidation of biodiesel was promoted by an increase in oxygen concentration, resulting in a larger uptake of fuel in the rubber due to internal cavitation, a greater decrease in the strain-at-break of NBR due to the coalescence of cavity, and a faster increase in the crosslinking density and carbonyl index due to the promotion of the oxidation of NBR. During the high-temperature autoclave ageing, less fuel was absorbed in the rubber, because the formation of hydroperoxides and acids was impeded. The extensibility of NBR aged in the autoclave decreased only slightly due to the cleavage of rubber chains by the biodiesel attack. The degradation of NBR in the absence of carbon black was explained as being due to oxidative crosslinking. The dissolution of ZnO crystals in the acidic components of biodiesel was retarded by removing the inter-particle porosity and surface defects through heat treating star-shaped ZnO particles. The rubber containing heat-treated ZnO particles swelled less in biodiesel than a NBR filled with commercial ZnO nanoparticles, and showed a smaller decrease in the strain-at-break and less oxidative crosslinking.

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  • 47.
    Al Husseinat, Ali
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Lignin Biorefining: Swelling and activation of fibers for lignin extraction2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the world’s transformation towards a bioeconomy, lignocellulosic biomass plays a key role as a substitute for fossil-based resources. Lignin is the most abundant source of renewable and naturally occurring aromatics and it constitutes 15-30% of lignocellulosic biomass. The technical lignin currently available on the market is limited in its applications because of its complex and poorly understood chemical structure. To contribute to the lignin-first biorefinery concept, this work investigates the effect of urea and carboxymethylation pretreatments on the yield as well as the chemical and physical properties of lignin. Characterization techniques such as Fourier-transform infra-red and nuclear magnetic resonance spectroscopy were utilized to analyze the molecular structure of the lignin product after extraction. It was shown that both pretreatment methods resulted in higher yields between 1% and 16%. The urea pretreatment had no effect on the chemical structure of the fibers nor the lignin. However, carboxymethylation altered the chemical structure of the lignin by adding carboxymethyl groups in both the aliphatic and phenolic regions. While increasing the pretreatment time increased the yield for both pretreatment methods, in the case of carboxymethylation it reduced the amount of quantifiable inter-unit linkages. Overall, the pretreatment methods discussed have potential use for lignin valorization.

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  • 48.
    Al Soubaihi, Rola Mohammad
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Saoud, Khaled Mohammad
    Virginia Commonwealth Univ Qatar, Liberal Arts & Sci Program, Doha, Qatar..
    Myint, Myo Tay Zar
    Sultan Qaboos Univ, Coll Sci, Dept Phys, POB 36, Muscat 123, Oman..
    Göthelid, Mats A.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Dutta, Joydeep
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    CO Oxidation Efficiency and Hysteresis Behavior over Mesoporous Pd/SiO2 Catalyst2021In: Catalysts, E-ISSN 2073-4344, Vol. 11, no 1, article id 131Article in journal (Refereed)
    Abstract [en]

    Carbon monoxide (CO) oxidation is considered an important reaction in heterogeneous industrial catalysis and has been extensively studied. Pd supported on SiO2 aerogel catalysts exhibit good catalytic activity toward this reaction owing to their CO bond activation capability and thermal stability. Pd/SiO2 catalysts were investigated using carbon monoxide (CO) oxidation as a model reaction. The catalyst becomes active, and the conversion increases after the temperature reaches the ignition temperature (T-ig). A normal hysteresis in carbon monoxide (CO) oxidation has been observed, where the catalysts continue to exhibit high catalytic activity (CO conversion remains at 100%) during the extinction even at temperatures lower than T-ig. The catalyst was characterized using BET, TEM, XPS, TGA-DSC, and FTIR. In this work, the influence of pretreatment conditions and stability of the active sites on the catalytic activity and hysteresis is presented. The CO oxidation on the Pd/SiO2 catalyst has been attributed to the dissociative adsorption of molecular oxygen and the activation of the C-O bond, followed by diffusion of adsorbates at T-ig to form CO2. Whereas, the hysteresis has been explained by the enhanced stability of the active site caused by thermal effects, pretreatment conditions, Pd-SiO2 support interaction, and PdO formation and decomposition.

  • 49.
    Al-Badri, Tuqa
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Biomimetic Surface Functionalization of Cellulose Fibers for Tuning Material Properties2020Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 50.
    Al-Badri, Tuqa
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Thermal degradation of PFAS in solid matter2024Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Per- and polyfluoroalkyl substances (PFAS) are man-made organic compound widely used in consumer and industrial products. They exhibit attractive properties such as resistance to water, heat, and grease. Therefore, PFAS are used in fire foam, non-stick pans, water-resistant clothes, make-up, and furniture. Recent studies have revealed that PFAS substances can be harmful to humans, animals, and the environment. Some PFAS substances have, therefore, been classified as persistent, bioaccumulative, and toxic (PBT), and very persistent and very bioaccumulative (vPvB). This means that PFAS resists degradation, accumulates in living organisms and biota, and inherits toxic effects.

    In previous and current research, the focus has been on the behavior of PFAS in different environmental settings. However, there is a gap in research on how these PFAS substances behave during thermal treatment processes in commercial facilities at temperatures of 850-950 °C and how effective the thermal degradation is. This project investigates the effectivity of thermal degradation via combustion and the fate of PFAS post-combustion, focusing on the formation of potentially hazardous by-products. Therefore, the combustion of PFAS-containing sewage sludge in a bench- scale bubbling fluidized bed (BFB) was to be conducted to fulfill the objective of this study. Due to hindrances, the experiments were performed in a conventional furnace furnace instead. Also, a literature study was conducted to investigate the fate of PFAS after combustion.

    From this study, it was concluded that thermal treatment via combustion at temperatures 850 and 950 °C is an effective method to degrade PFAS in sewage sludge. Also, the literature study investigation revealed that persistent short-chain PFCAs were most abundant in the ash, liquid, and gaseous residues after thermal treatment. A few investigations indicate that thermal treatment of PFAS-containing matter possibly results in ozone-depleting compounds. Based on the conducted literature study, there is a lack of strong evidence that supports the claim of the formation of ozone- depleting compounds during combustion of PFAS.

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