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  • 1.
    Escamilla-Roa, Elizabeth
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Cartwright, Julyan H. E.
    Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, Armilla Granada, Spain. Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, Granada, Spain.
    Sainz-Díaz, C. Ignacio
    Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, Armilla Granada, Spain.
    Chemobrionic Fabrication of Hierarchical Self‐Assembling Nanostructures of Copper Oxide and Hydroxide2019In: ChemSystemsChem, E-ISSN 2570-4206, Vol. 1, no 3, article id e1900011Article in journal (Refereed)
    Abstract [en]

    Copper oxide nanostructures have great potential use in a plethora of nanotechnology applications including nanoelectronics, photovoltaics, sensors, electrochemistry, and pharmacology. In the present work we show how hierarchically nano‐structured copper oxide and hydroxide may be prepared through self‐assembly from CuSO4 salt and silicate solutions using the chemobrionic growth process of a chemical garden. Procedures were explored using the cupric salt in either solid (pellet and seed growth methods) or liquid phase (fluid injection techniques). Self‐assembling nanostructures were characterized by means of environmental scanning electron microscopy (ESEM) with energy‐dispersive X‐ray spectroscopy (EDX) analysis, micro‐Raman spectroscopy and X‐ray diffraction. Our results show the formation of crystalline aggregates of copper oxide and hydroxide in complex hierarchical nanostructured forms including fans, flowers, petals, skeins, lentils, and sheaves. Analytical methods corroborate that these nanostructures may be selected in shape and chemical composition with the reaction conditions.

  • 2.
    Escamilla-Roa, Elizabeth
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), Granada, Spain.
    Zorzano Mier, María-Paz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Centro de Astrobiología (INTA-CSIC), Torrejón de Ardoz, Madrid, Spain.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), Granada, Spain.
    Hernández-Laguna, Alfonso
    Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), Granada, Spain.
    Saínz-Díaz, C.Ignacio
    Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), Granada, Spain.
    DFT study of the reduction reaction of calcium perchlorate on olivine surface: Implications to formation of Martian’s regolith2020In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 512, article id 145634Article in journal (Refereed)
    Abstract [en]

    Perchlorates have been found widespread on the surface of Mars, their origin and degradation pathways are not understood to date yet. We investigate here, from a theoretical point of view, the potential redox processes that take place in the interaction of Martian minerals such as olivine, with anhydrous and hydrated perchlorates. For this theoretical study, we take as mineral substrate the (1 0 0) surface of forsterite and calcium perchlorate salt as adsorbate. Our DFT calculations suggests a reduction pathway to chlorate and chlorite. When the perchlorate has more than 4 water molecules, this mechanism, which does not require high-temperature or high energy sources, results in parallel with the oxidation of the mineral surface, forming magnesium peroxide, MgO2, and in the formation of ClO3, which through photolysis is known to form ClO-O2. Because of the high UV irradiance that reaches the surface of Mars, this may be a source of O2 on Mars. Our results suggest that this process may be a natural removal pathway for perchlorates from the Martian regolith, which in the presence of atmospheric water for salt hydration, can furthermore lead to the production of oxygen. This mechanism may thus have implications on the present and future habitability of the Martian surface.

  • 3.
    Gergely, Andras
    et al.
    Department of Physical Chemistry, Institute of Chemistry, University of Pannonia, Egyetem, Hungary .
    Szabó, Péter
    Department of General and Inorganic Chemistry, Institute of Chemistry, University of Pannonia, Egyetem, Hungary .
    Krojer, Antal
    Department of Inspection and Maintenance, Mol Nyrt., Olajmunkás, Hungary .
    Nagy, Bence
    Refining Research and Innovation, Mol Nyrt., Hungary .
    Kristof, Tamas
    Department of Physical Chemistry, Institute of Chemistry, University of Pannonia, Egyetem, Hungary .
    Hydrogen Sulfide Corrosion of Carbon and Stainless Steel Alloys in Mixtures of Renewable Fuel Sources under Co-Processing Conditions2018In: Modern Applied Science, ISSN 1913-1844, E-ISSN 1913-1852, Vol. 12, no 4, p. 227-255Article in journal (Refereed)
    Abstract [en]

    Corrosion rates of steel alloys were investigated in gas oil and its mixture with waste cooking oil and animal waste lard over 1, 3, 7 and 21 days under desulfurizing condition. Co-processing conditions were attempted to simulate by batch-reactor experiment at temperatures between 200 and 300oC and pressures between 20 and 90 bar in the presence of 2 volume% hydrogen sulfide. Integral and differential corrosion rates were defined by weight losses. Intense sulfide corrosion of carbon steels was less impacted by the biomass sources. Thinner scales in gas oil was probably due to frequent cohesive failure, whereas thicker layers in biomass mixtures were allowed to form to afford limited physical protection. The high corrosion rate of low alloy steel with temperature over time is related to inefficient protection by the metal sulfide scales. Greater activation energy and enthalpy balance in the formation of activated complex is expected to reflect in thick cohesive scales. Loose layers and the less unfavorable entropy balance in the transition state did not lead to valuable barrier protection. High sulfide corrosion resistance of stainless steels is in chemical in nature markedly impacted by the biomass fuel sources and contributed especially by the acidic species. Corrosion rates increased with temperature by magnitude similar to those of carbon steels, which probably owes to the less unfavorable entropy and free energy balance between the initial and transition states of the reactants.

  • 4.
    Hegedűs, Péter
    et al.
    Department of General and Inorganic Chemistry, Institute of Chemistry, University of Pannonia, Hungary.
    Szabó-Bárdos, Erzsébet
    Department of General and Inorganic Chemistry, Institute of Chemistry, University of Pannonia, Hungary.
    Horváth, Ottó
    Department of General and Inorganic Chemistry, Institute of Chemistry, University of Pannonia, Hungary.
    Szabó, Péter
    Department of Analytical Chemistry, Institute of Chemistry, University of Pannonia, Hungary.
    Horváth, Krisztián
    Department of Analytical Chemistry, Institute of Chemistry, University of Pannonia, Hungary.
    Investigation of a TiO2 photocatalyst immobilized with poly(vinyl alcohol)2017In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 284, p. 179-186Article in journal (Refereed)
    Abstract [en]

    Immobilization of TiO2 photocatalyst was realized with application of poly(vinyl alcohol) (PVA). However, these PVA-based foils were too instable to be used for photocatalytic water cleaning. Their stability could be significantly enhanced by a thermal treatment, but this procedure generated various water-soluble derivatives such as aldehydes, ketones, and aromatic species. Photocatalytic pre-treatment of the foils proved to be suitable to remove these products from the surface of the composite. After three subsequent pre-treating cycles of irradiation and rinsing, the PVA-TiO2 foil became applicable for photocatalytic degradation of Triton X-100, a widely used non-ionic detergent. The composite catalyst kept its stability and efficiency even after some cycles of re-usage, while its surface underwent a perceptible, although quantitatively negligible degradation.

  • 5.
    Hernández-Laguna, Alfonso
    et al.
    Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), Granada, Spain.
    Pérez del Valle, Carlos
    DCM and ISTerre, Université Grenoble Alps, France.
    Hernández-Haro, Noemí
    Departament de Química, Universitat de les Illes Balears, Palma de Mallorca, Spain.
    Ortega-Castro, Joaquín
    Departament de Química, Universitat de les Illes Balears, Palma de Mallorca, Spain.
    Muñoz-Santiburcio, Daniel
    Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), Granada, Spain. CIC nanoGUNE, San Sebastián, Spain.
    Vidal, Isaac
    Apoyo a la Docencia - Centro de Servicios de Informática y Redes de Comunicaciones, Universidad de Granada, Granada, Spain. Grupo de Modelización y Diseño Molecular, Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Granada, Granada, Spain.
    Sánchez-Navas, Antonio
    Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), Granada, Spain. Departamento de Mineralogía y Petrología, Facultad de Ciencias, Universidad de Granada, Granada, Spain.
    Escamilla-Roa, Elizabeth
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), Granada, Spain..
    Sainz-Díaz,, Claro Ignacio
    Compressibility of 2M1 muscovite-phlogopite series minerals2019In: Journal of Molecular Modeling, ISSN 1610-2940, E-ISSN 0948-5023, Vol. 25, no 11, article id 341Article in journal (Refereed)
    Abstract [en]

    Muscovite (Ms) and phlogopite (Phl) belong to the 2:1 dioctahedral and trioctahedral layer silicates, respectively, and are the end members of Ms-Phl series minerals. This series was studied in the 2M1 polytype and modeled by the substitution of three Mg2+ cations in the Phl octahedral sites by two Al3+ and one vacancy, increasing the substitution up to reach the Ms. The series was computationally examined at DFT level as a function of pressure to 9 GPa. Cell parameters as a function of pressure and composition, and bulk moduli as a function of the composition agrees with the existing experimental results. The mixing Gibbs free energy was calculated as a function of composition. From these data, approximated solvi were calculated at increasing pressure. A gap of solubility is found, decreasing the gap of solubility at high pressure.

  • 6.
    Ishikawa, Kunio
    et al.
    Department of Biomaterials, Faculty of Dental Science, Kyushu University, Maidashi, Higashi-Ku, Fukuoka, Japan.
    Garskaite, Edita
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering. Institute of Chemistry, Vilnius University, Vilnius, Lithuania.
    Kareiva, Aivaras
    Institute of Chemistry, Vilnius University, Vilnius, Lithuania.
    Sol–gel synthesis of calcium phosphate-based biomaterials: A review of environmentally benign, simple, and effective synthesis routes2020In: Journal of Sol-Gel Science and Technology, ISSN 0928-0707, E-ISSN 1573-4846, Vol. 94, no 3, p. 551-572Article, review/survey (Refereed)
    Abstract [en]

    In this review article the available results about application of sol–gel synthesis method for the preparation of different calcium phosphates and composite materials are summarized. The attention is paid to calcium phosphate-containing compounds which show the biological properties and could be used as potential phosphate bioceramics in medicine. It was demonstrated that the sol–gel synthesis method is a powerful tool for the synthesis of calcium hydroxyapatite and other phosphates, and different calcium phosphate-based composites at mild synthetic conditions resulted in high reproducibility, high phase purity, and desired morphology. Thus, the sol–gel synthesis method enables the researchers to develop biomaterials with superior features in terms of biomedical applications.

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  • 7.
    Neikter, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Microstructure and hydrogen embrittlement of additively manufactured Ti-6Al-4V2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The work of this doctoral thesis has been performed between the 24th of August 2015 to the 6th of September 2019. The general purpose of this work has been to increase the knowledge of additively manufactured Ti-6Al-4V when it comes to microstructure, texture and hydrogen embrittlement. Several additive manufacturing (AM) processes have been addressed, the main focus, however, has been on the two processes electron beam melting (EBM) and selective laser melting (SLM). The work has been performed at Luleå University of Technology and at Monash Centre of Additive Manufacturing (MCAM), which is a part of Monash University, Melbourne Australia. GKN Aerospace Engine Systems has been involved in the work as a collaborative industrial partner. Where the main interaction and support has been between GKN in Trollhättan, Sweden. GKNs facility in Filton, United Kingdom, however, has also been involved in sample production. The texture measurements using neutron time of flight (TOF) diffraction were performed in Dubna, Russia at Frank Laboratory of Neutron Physics at the Joint Institute for Nuclear Research, using the spektrometer kolitshestvennovo analiza tekstury (SKAT) instrument and in Los Alamos at Los Alamos Neutron Science Center, using the texture instrument high pressure preferred orientation (HIPPO). The interest of specifically additively manufactured Ti-6Al-4V originates from GKN Aerospace Engine Systems as they have been contracted to manufacture parts for the Ariane rockets. In aerospace, weight is of utter importance as reduced weight of the components reduce the fuel costs and makes it possible to transport increased loads. Therefore, titanium has been suggested to replace heavier metal alloys (such as nickel-based superalloys) due to titanium’s high specific strength and overall good properties. The work has been managed under the supervision of Professor Marta-Lena Antti, Professor Robert Pederson and Dr. Pia Åkerfeldt at Luleå University of Technology and by Professor Xinhua Wu and Professor Aijun Huang at MCAM. The project has been financed by three parties Space for Innovation and Growth (RIT), Nationellt Rymdtekniskt Forskningsprogram (NRFP) and the Graduate School of Space Technology. The thesis is composed of a literature review along with the appended papers that have been written throughout the duration of the project. The purpose of the literature review is to give the reader a broader knowledge and context about the theory behind the work conducted during the Ph.D. project. The thesis commences with a theoretical background about titanium, its crystal structures, microstructure, and AM. The chapter about AM is divided into three sub-chapters, explaining the two different AM sub-groups directed energy deposition (DED) and powder bed fusion (PBF). Then the chapter finalizes with explaining the benefits and drawbacks with AM. Once these subjects been explained there is a chapter explaining AM built Ti-6Al-4V. The theme of this chapter is the differences in the microstructure of AM built and conventional built Ti-6Al-4V, where phenomena like chessboard pattern and layers bands are discussed, followed by a comparative section of the mechanical properties. The chapter about AM built Ti-6Al-4V is followed by a chapter about texture where the two texture techniques electron backscattered diffraction (EBSD) and neutron (TOF) diffraction are explained. The literature review then continues with the chapters neutron tomography, hydrogen embrittlement, and fatigue crack growth. Then there is a chapter about the materials and experimental methods that have been used to perform all the experiments, then a summary of all the papers and conclusions. After the conclusions, the thesis finalizes with a chapter about possible future work and an outlook into the future of AM. In the end, the papers I to IV are appended.  

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  • 8.
    Neikter, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Microstructure and Texture of Additive Manufactured Ti-6Al-4V2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Additive manufacturing (AM) for metals is a manufacturing process that has increased a lot in popularity last few years as it has experienced significant improvements since its beginning, both when it comes to accuracy and deposition rates. There are many different AM processes where the energy sources and deposition methods varies. But the common denominator is their layer wise manufacturing process, melting layer on layer. AM has a great design freedom compared to conventional manufacturing, making it possible to design new structures with decreased weight and increased performance.  A drawback is slow manufacturing speeds, making it more expensive. But when it comes to low lot sizes and complex structures AM is very competitive. So, for the aerospace and space industry AM is a good option as manufacturing cost is less of an issue and where saving weight is of great concern, both environmentally and economically.  There are however many topics left to research before additive manufactured titanium can be widely adopted for critical components, such as microstructure and texture development and its correlation to mechanical properties. The aim of this work has been to investigate the microstructure and texture of various AM processes. Microstructural features such as prior β grains, grain boundary α (GB-α), α laths, α colonies have been characterized along with hardness measurements for 5 different AM processes. Some of these AM processes have also been investigated in the SKAT instrument in Dubna, Russia, to obtain their texture. These textures have then been compared with one another and correlated to previous microstructural investigations and mechanical properties. This is important knowledge as the microstructure and the texture sets the basis for the mechanical properties. In case there is a high texture, the material can have anisotropic mechanical behavior, which could be either wanted or unwanted for different applications.  

    Some the findings are that α phase was found to increase in the prior β grain boundary for the AM processes with low cooling rates, while it was discontinuous and even non-present for the AM processes with high cooling rates. The prior β size are larger for the directed energy deposition (DED) processes than for the powder bed fusion (PBF) processes. Parallel bands were present for the DED process while being non-present for the PBF processes. Concerning the texture, it was found that LMwD had a higher texture than EBM and SLM. Texture inhomogeneity was also found for the LMwD process., where two parts of the same sample was investigated and the material closer to the surface had higher texture. 

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  • 9.
    Papp, Máte
    et al.
    Department of Organic Chemistry, Institute of Chemistry, University of Pannonia.
    Szabó, Péter
    Department of Analytical Chemistry, University of Pannonia.
    Srankó, Dávid
    Department of Surface Chemistry and Catalysis, Centre for Energy Research, Hungarian Academy of Sciences.
    Sáfrán, György
    Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences.
    Kollár, L.
    Department of Inorganic Chemistry, MTA-PTE Research Group for Selective Chemical Syntheses, University of Pécs.
    Skoda-Földes, R.
    Department of Organic Chemistry, Institute of Chemistry, University of Pannonia.
    Mono- and double carbonylation of aryl iodides with amine nucleophiles in the presence of recyclable palladium catalysts immobilised on a supported dicationic ionic liquid phase2017In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 70, p. 44587-44597Article in journal (Refereed)
    Abstract [en]

    Silica modified with organic dicationic moieties proved to be an excellent support for palladium catalysts used in the aminocarbonylation of aryl iodides. By an appropriate choice of the reaction conditions, the same catalyst could be used for selective mono- or double carbonylations leading to amide and α-ketoamide products, respectively. The best catalyst could be recycled for at least 10 consecutive runs with a loss of palladium below the detection limit. By the application of the new support, efficient catalyst recycling could be achieved under mild reaction conditions (under low pressure and in a short reaction time). Palladium-leaching data support a mechanism with dissolution—re-precipitation of the active palladium species.

  • 10.
    Raudoniene, Jolanta
    et al.
    Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Vilnius, Lithuania.
    Skaudzius, Ramunas
    Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Vilnius, Lithuania.
    Zarkov, Aleksej
    Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Vilnius, Lithuania.
    Selskis, Algirdas
    Center for Physical Sciences and Technology, Vilnius, Lithuania.
    Karlsson, Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Kareiva, Aivaras
    Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Vilnius, Lithuania.
    Garskaite, Edita
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wet-chemistry synthesis of shape-controlled Ag3PO4 crystals and their 3D surface reconstruction from SEM imagery2019In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 345, p. 26-34Article in journal (Refereed)
    Abstract [en]

    A simple chemical solution-based synthesis route has been developed to prepare uniform and shape-controllable Ag3PO4 crystals. Tetrapod- and cube-shaped crystals having a size of about 9–10 μm were prepared from AgNO3 and NH4H2PO4 precursors, and pseudo-octahedral (equiaxial) crystals were prepared from AgNO3 and (NH4)2HPO4. TEM analysis revealed Ag3PO4 crystals to be electron beam sensitive materials, which under a voltage of 200 kV decompose to the metallic Ag, thereby demonstrating the difficulty in determining crystal facets and structural defects using conventional electron diffraction studies. UV–Vis diffuse reflectance spectroscopy was used to study the correlation between structural and optical properties of surfaces of Ag3PO4 crystals. Furthermore, a spatial 3-dimentional (3D) reconstruction of Ag3PO4 surface structures was performed from SEM images. The reconstruction produced realistic 3D mesh models, insomuch that the 3D reconstructed structures provided extra information about the examined crystals. Results suggested that the proposed synthesis route and performed spatial reconstruction of Ag3PO4 had the potential for simulating processing conditions to produce various microcrystals and explore material surface structures and reconstruction of microstructures.

  • 11.
    Saeed, Sumbul
    et al.
    Institute of Biotechnology and Genetic Engineering, University of Sindh-76080, Jamshoro, Pakistan.
    Rafiq, Muhammad
    Institute of Biotechnology and Genetic Engineering, University of Sindh-76080, Jamshoro, Pakistan.
    Baloach, Qurrat-ul-Ain
    Dr. M. A. Kazi Institute of Chemistry University of Sindh-76080, Jamshoro, Pakistan.
    Naqvi, Syed Habib Ahmed
    Institute of Biotechnology and Genetic Engineering, University of Sindh-76080, Jamshoro, Pakistan.
    Tahira, Aneela
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Willander, Magnus
    Department of Science and Technology, Campus Norrkoping, Linkoping University.
    Akhtar, Mansoor
    Key Lab of Polyoxometalate of Science, Northeast Normal University, Changchun City, Jilin Province, P. R. China.
    Ibupoto, Zafar Hussain
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science. Dr. M. A. Kazi Institute of Chemistry University of Sindh-76080, Jamshoro, Pakistan.
    Realization of Peptone Biosensor Based on Newly Prepared NiO Nanostructures2017In: Sensor Letters, ISSN 1546-198X, E-ISSN 1546-1971, Vol. 15, no 10, p. 822-826Article in journal (Refereed)
    Abstract [en]

    The present study authenticates the fabrication of nickel oxide porous shaped nanostructure by hydrothermal method. The novel and functionalized nickel oxide nanomaterial were visualized by using scanning electron microscopy (SEM) and X-ray diffraction techniques (XRD). NiO nanomaterial advertised sensitive, selective and attracted morphology for the development of peptone biosensor. Phenylalanine displays a soft template and growth directing agent for the developing of nickel oxide low dimension nanostructures. The nickel oxide nanomaterial together with protease possesses tremendous role towards the oxidation potential phenomena and transfer of anodic electro-catalytic current for the peptone. The generation of low potential electrochemical signals exhibited the determination of peptone by utilizing different electrochemical techniques for the given concentration ranging from 0.1 mM to 2.5 mM with the measured limit of detection about 0.002 mM with a sensitivity of 107200 μA/mMCm2. The well-defined and highly developed sensor system provides the standard platform for the fabrication and functioning of new devices that are helpful for the determination of many biological macromolecules. The presented peptone biosensor is highly selective, sensitive, and reproducible that could also be useful for the determination of peptone from various milk samples.

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  • 12.
    Simon, Hellgren
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Secondary Steel Metallurgy Slag Design and MgO-C Refractory Implications: Theoretical and Practical Considerations2019Independent thesis Advanced level (professional degree), 300 HE creditsStudent thesis
    Abstract [en]

    MgO-C based refractory materials, often used in secondary steel making, are exposed to variouswear mechanisms in its application. The wear could be divided into oxidative, chemical andabrasive categories, all behaving differently and all being influenced by different factors. Dueto the importance of minimizing material loss and to the environmental challenges to run asustainable industry, it is of interest to gain more knowledge of the behavior of the refractorymaterial in use. The present thesis work specifically investigated slag designed of the CaOSiO2-Al2O3-MgO (CSAM) system as well as the chemical and oxidative wear mechanisms ofthree different MgO-C based refractory materials from Höganäs AB, Halmstadverken, whichcontained 5, 10 and 12 wt% carbon (labeled T05, T10 and T12). Different CSAM slags weredesigned to meet certain process criteria such as MgO and CaO saturations and wereinvestigated through thermodynamic calculations using the FactSage software and throughlaboratory scaled slag smelting experiments. The oxidation effect on the refractory material wasalso studied through pre-heating simulations in chamber furnaces, similar to the pre-heating ofa re-built ladle furnace.The thermodynamic calculations made in FactSage 7.0, using the FactPS and FToxid databases, resulted in a few different slag designs with different properties. A few different slagsfulfilled the CaO and MgO saturation limits proposed by Höganäs AB and could be consideredto test experimentally for further evaluation. The simulations also showed trends on how theliquid viscosity behaved with different slag compositions and how the solids content changedwith temperature.The oxidation experiments were performed on the different MgO-C refractory types, where thebricks with 10% carbon also contained Al2O3 antioxidants. The experiments showed that themass loss during the pre-heating is greater for refractory with higher carbon content, withexception to T10, where the mass losses were measured to 3.76 – 4.01%, 1.06 – 1.28% and6.28 – 6.33% for T05, T10 and T12 respectively. Further, the oxidation depth of each materialwas measured to 9-10 mm, 2-3 mm and 2-5 mm for the T05, T10 and T12. The experimentsalso showed that T12 refractory in particular was very susceptible to abrasive wear after beingoxidized.The slag smelting experiments were carried out through two different methods, by melting slagin MgO-C crucibles and by melting pressed slag briquettes on top of refractory bricks. Theformer tests mainly showed that the methodology was not suitable for this type of refractorymaterial due to the crucibles cracking during the experiments. The latter experiments showedsome general behaviour of the different components in the slag, where Ca, Al and Fe stayednear the surface, and Si and Mg penetrated deeper. The spinel formation at the refractory surfacewas then concluded to be the reason for Al not penetrating deeper. Further it was concludedthat no significant difference in refractory dissolution was seen between slags with- and withoutMgO, other than possibly a small increase in refractory dissolution for the latter.

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  • 13.
    Szabo, Peter
    et al.
    Department of Analytical Chemistry, University of Pannonia.
    Zsirka, Balázs
    Institute of Environmental Engineering, University of Pannonia.
    Fertig, Dávid
    Department of Analytical Chemistry, University of Pannonia.
    Horváth, Erzsébet
    Institute of Environmental Engineering, University of Pannonia.
    Csizmadia, Tamás
    Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University.
    Kristóf, János
    Institute of Environmental Engineering, University of Pannonia.
    Delaminated kaolinites as potential photocatalysts: Tracking degradation of Na-benzenesulfonate test compound adsorbed on the dry surface of kaolinite nanostructures2017In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 287, no Supplement C, p. 37-44Article in journal (Refereed)
    Abstract [en]

    Abstract Based on their bandgap values, kaolins can have semiconductive and photocatalytic properties enabling them to use as potential photocatalysts. Kaolinite nanostructures (Knano) and silver-coated kaolinite nanohybrids (Knano(Ag)) were made of ordered (Hinkley Index, HI=1.4) and disordered (HI=0.3) kaolins via intercalation/deintercalation. The book-type kaolin built up from tetrahedral(T)-octahedral(O) double layers has very low photocatalytic activity. At the same time the nanostructures made of individual TO layers show photochemical activity in spite of the fact that their bandgap values are comparable to those of the book-type ones. The presence of Ag on the surface significantly reduced the bandgap and shifted the excitation wavelength towards the visible range. This phenomenon supports the supposition that kaolinite has some semiconductive character. This work presents the connection between photocatalytic activity and morphology for the first time. The surface activity of kaolinite nanostructures and their Ag-hybrids was studied through the decomposition of sodium-benzenesulfonate (BS) test compound with attenuated total reflection Fourier transform infrared spectroscopy (FT-IR/ATR). BS decomposition can be detected on the Knano surface but with low efficiency. The presence of silver can significantly improve the mineralization efficiency. No correlation was found between the activity and the quantity of Ti and Fe contaminants and the amount of Ag on the surface. However, the activity could be correlated with the order-dependent morphology (mixture of semi-hexagonal and nanoscroll-type structures), the pore size and with the increase of the surface coverage.

  • 14.
    Zsirka, Balázs
    et al.
    University of Pannonia, Institute of Environmental Engineering, Hungary.
    Horváth, Erzsébet
    University of Pannonia, Institute of Environmental Engineering, Hungary.
    Szabó, Péter
    University of Pannonia, Department of Analytical Chemistry, Hungary.
    Juzsakova, Tatjána
    University of Pannonia, Institute of Environmental Engineering, Hungary.
    Szilágyi, Róbert K.
    Department of Chemistry and Biochemistry, Montana State University, USA.
    Fertig, Dávid
    University of Pannonia, Department of Analytical Chemistry, Hungary.
    Makó, Éva
    University of Pannonia, Institute of Materials Engineering, Hungary.
    Varga, Tamás
    University of Szeged, Department of Applied and Environmental Chemistry, Hungary.
    Kónya, Zoltán
    University of Szeged, Department of Applied and Environmental Chemistry, Hungary; MTA-SZTE Reaction Kinetics and Surface Chemistry Research Group, Hungary .
    Kukovecz, Ákos
    University of Szeged, Department of Applied and Environmental Chemistry, Hungary; MTA-SZTE “Lendület” Porous Nanocomposites Research Group, Hungary.
    Kristóf, János
    University of Pannonia, Department of Analytical Chemistry, Hungary.
    Thin-walled nanoscrolls by multi-step intercalation from tubular halloysite-10 Å and its rearrangement upon peroxide treatment2017In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 399, p. 245-254Article in journal (Refereed)
    Abstract [en]

    Surface modification of the halloysite-10 Å mineral with tubular morphology can be achieved by slightly modified procedures developed for the delamination of kaolinite minerals. The resulting delaminated halloysite nanoparticles have unexpected surface/morphological properties that display, new potentials in catalyst development. In this work, a four-step intercalation/delamination procedure is described for the preparation of thin-walled nanoscrolls from the multi-layered hydrated halloysite mineral that consists of (1) intercalation of halloysite with potassium acetate, (2) replacement intercalation with ethylene glycol, (3) replacement intercalation with hexylamine, and (4) delamination with toluene. The intercalation steps were followed by X-ray diffraction, transmission electron microscopy, N2adsorption-desorption, thermogravimetry, and infrared spectroscopy. Delamination eliminated the crystalline order and the crystallite size along the ‘c’-axis, increased the specific surface area, greatly decreased the thickness of the mineral tubes to a monolayer, and shifted the pore diameter toward the micropore region. Unexpectedly, the removal of residual organics from intercalation steps adsorbed at the nanoscroll surface with a peroxide treatment resulted in partial recovery of crystallinity and increase of crystallite size along the ‘c’-crystal direction. The d(001) value showed a diffuse pattern at 7.4–7.7 Å due to the rearrangement of the thin-walled nanoscrolls toward the initial tubular morphology of the dehydrated halloysite-7 Å mineral.

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