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This study was motivated by the excess oxygen that likely results from the current transition to hydrogen-based Swedish steel production. The potential usability of large amounts of oxygen in a process gas for iron ore pellet induration could improve the process efficiency in terms of fuel consumption and productivity. Iron ore pellets constitute the main raw material used in Scandinavian steel production. Knowledge of the effects of the process-gas oxygen level on induration is a prerequisite for establishing if, how, and to what extent oxygen enrichment can be exploited in an optimum manner to control temperature development and oxidation, while maintaining pellet quality. The objectives of this study are as follows: 1) to investigate the effects of the oxygen level in the inflow gas on pellet bed oxidation during induration, as well as the effects on the bed-scale temperature, oxidation degree, and cold compression strength (CCS) development; and 2) to identify the oxidation mechanisms corresponding to various oxygen levels and thermal histories. The current knowledge regarding the effects of high oxygen levels in the gas on oxidation is based on small-scale experiments; this study was conducted on a larger bed-scale and will thus contribute significantly to the knowledge pool of bed-scale effects resulting from different oxygen levels in the inflow process gas. An interrupted pot furnace experimental method was used, with the highest investigated oxygen level in the gas at 40% and an approximate bed-scale of 100 kg of pellets. The following conclusions were drawn from this study. First, efficient heating and a high degree of oxidation of an entire bed were rapidly achieved with the highest investigated oxygen level (40% O₂) compared to the results of the lower oxygen levels (6%, 13% and 30% O₂). The gas with 40% O₂ yielded improved pellet properties and a more uniform oxidation degree along the bed, compared to beds exposed to gas with lower O₂. Second, the temperature at the bottom of the bed increased more rapidly when exposed to a higher oxygen content in the gas compared to when only the gas temperature was increased. Third, the mechanical pellet properties (CCS and macrostructure) were improved in a bed exposed to gas with 40% O₂ compared to beds exposed to gas with lower oxygen levels. Finally, pellets from local conditions with comparable thermal histories oxidised according to similar mechanisms regardless of the oxygen level. Hence, it was demonstrated that the oxygen level influences the oxidation rate, whilst the temperature affects the oxidation mechanism. The overall trends in terms of the positive effect from the high oxygen content in the gas are promising, as they serve as a starting point for enabling faster production rates in the future. / <p>E632 and a digital meeting in Zoom or Teams. Maximum 8 people will be allowed in E632 due to the covid-19 pandemic situation.</p> / HYBRIT research program 1

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Polylactide homopolymers with pendent carboxylic acid functional groups have been designed and synthesized to be studied as magnetite nanoparticle dispersion stabilizers. Magnetic nanoparticles are of interest for a variety of biomedical applications including magnetic field-directed drug delivery and magnetic cell separations. Small magnetite nanoparticles are desirable due to their established biocompatibility and superparamagnetic (lack of magnetic hysteresis) behavior. For in-vivo applications, it is important that the magnetic material be coated with biocompatible organic materials to afford dispersion characteristics or to further modify the surfaces of the complexes with biospecific moieties. The acid-functionalized silane endgroup was utilized as the dispersant anchor to adsorb onto magnetite nanoparticle surfaces and allowed the polylactide to extend into various solvents to impart dispersion stability. The homopolymers were complexed with magnetite nanoparticles by electrostatic adsorption of the carboxylates onto the iron oxide surfaces, and these complexes were dispersible in dichloromethane. The polylactide tailblocks extended into the dichloromethane and provided steric repulsion between the magnetite-polymer complexes. The resultant magnetite-polymer complexes were further incorporated into controlled-size nanospheres. The complexes were blended with poly(ethylene oxide-b-D,L-lactide) diblock copolymers to introduce hydrophilicity on the surface of the nanospheres with tailored functionality. Self-assembly of the PEO block to the surface of the nanosphere was established by utilizing an amine terminus on the PEO to react with FITC and noting fluorescence. / Ph. D.

Superparamagnetic nanoparticles have potential applications in targeted drug delivery and as magnetic resonance imaging contrast agents. Magnetite clusters are of particular interest for these applications because they provide higher magnetic flux (under a magnetic field) than individual magnetite nanoparticles, are biocompatible, and their size and compositions can be controlled. This thesis involves the controlled synthesis and characterization of clusters composed of magnetite nanoparticles stabilized with an amphiphilic block copolymer. It outlines a method to design and form well-defined and colloidally stable magnetite clusters. A Multi Inlet Vortex mixer (MIVM) was used because it is a continuous process that yields particles with relatively narrow and controlled size distributions. In the MIVM, four liquid streams collide under turbulent conditions in the mixing chamber where clusters form within milliseconds. The formation of magnetite clusters was studied in the presence of amphiphilic block copolymers containing poly (ethylene oxide) to provide steric stabilization and control of size distributions using flash nanoprecipitation. First, the mixer was tested using β-carotene as a model compound to form nanoparticles stabilized with an amphiphilic triblock copolymer poly(propylene oxide)-b-poly(ethylene oxide) (F127) at different Reynolds numbers and supersaturation values. Size analysis was done using dynamic light scattering and nanoparticle tracking analysis techniques. The cluster structure was studied using electron microscopy and magnetite compositions were measured using thermogravimetric analysis. Finally, the stability of magnetite clusters was studied over time and the effect of an applied magnetite field on the colloidal stability was investigated. / Master of Science

Interaction between minerals and bacteria represents an abundant natural phenomenon depictingnature's complexity and how abiotic and biotic components are intertwined. This interaction is evidentin modern-day ecosystems, and it significantly shaped the early stage of life on Earth by influencinggeochemical processes. Evidence of this interaction includes microbialites. In the first part, this master's thesis explores the impact of iron-redox bacteria on the magneticproperties of synthetic and natural magnetic materials, with significant implications for understandingearly Earth conditions and paleoenvironments. In the second part, the magnetic signal recorded in thesediment core from the Baltic Sea is examined to identify the ferrimagnetic minerals responsible for itand their origin (biotic versus abiotic). A better understanding of the origin of ferrimagnetic mineralsallows for a more conclusive interpretation of palaeomagnetism and palaeoenvironmental history of theBaltic Sea. In both parts, the change in magnetic susceptibility was used as the main method to depictmechanisms of mineral-bacteria interaction. Experiment with iron-oxidising bacteria (Leptothrix mobilis) showed a decrease in magneticsusceptibility over time, consistent with the oxidation of solid iron/magnetic materials. However, asmall difference between bacteria culture and control samples points out that the decrease is caused byabiotic oxidation rather than bacterial. Supporting evidence is the absence of viable cells in all bacterialsamples, suggesting that L. mobilis did not grow in these experiments. In experiments with iron-reducing bacteria (Geobacter sulfurreducens), magnetic susceptibility increased by 7%. Controlsamples with the same reducing media did not show a change in magnetic susceptibility, indicating thatthe susceptibility change is caused by bacterial reduction of iron oxides. Magnetic susceptibility signal obtained in the sediment core from the Baltic Sea indicates rapidlyoxidising, ferrimagnetic nanoparticles in two organic-rich sapropels. The pattern of the signal isconsistent with the presence of bacterial greigite (magnetofossils). Contrary to previous research, nomagnetic enhancement is observed in these layers.  Magnetic susceptibility, as a non-destructive and relatively simple method, may serve as a significantindicator of mineral-bacterial interactions. Combining it with other techniques and methods can providedeeper insights into the mechanisms behind these interactions. This approach can reveal the importanceof these interactions on early Earth, enhance our understanding of palaeomagnetism, and unveil possibleconditions of ancient environments.

Die Wechselwirkung von Wasser und CO2 mit Oxidoberflächen ist vor allem ein bedeutsames Thema für Umweltnaturwissenschaftler. Der Gebrauch von Wasser als Wasserstoff-Ressource für die Reduktion/Hydrierung von CO2 würde zu einer Reduktion der CO2-Emmissionen in der Atmosphäre führen. Trotz einiger Fortschritte in diesem Bereich sind weitere grundlegende Studien notwendig, um die Wechselwirkung von Wasser und CO2 mit Metalloxidoberflächen zu verstehen und darauf aufbauend eine rationale Gestaltung Katalyse-Prozesse zu ermöglichen. Die vorliegende Arbeit präsentiert grundlegende Studien der Adsorption von Wasser und CO2 auf wohldefinierten Fe3O4(111) Filmen, welche auf einem Pt(111) Einkristall aufgewachsen wurden. Die Oberfläche wurde zuerst durch Adsorption von CO als Sondenmolekül gestützt. Es zeigt sich, dass die Magnetitoberfläche aus einer 1/4-Monoschicht tetraedrisch angeordneter Fe3+-Ionen auf einer dicht gepackten Sauerstoffschicht besteht. Auf dieser gut charakterisierten Oberfläche wurde die Wechselwirkung mit Wasser und CO2 sodann detailliert untersucht. Kombinierte IRAS- und TPD-Daten deckten auf, dass Wasser leicht an der Oberfläche dissoziiert und unter Einbeziehung von Sauerstoffatomen aus dem Wasser selbst bzw. von der Oxidoberfläche zwei Hydroxylspezies bildet. Diese Spezies fungieren als Anker für die molekulare Wasseradsorption, die schließlich zu einer geordneten Struktur führt. DFT-Rechnungen rationalisieren diese Ergebnisse im Rahmen einer kooperativen Bildung des Wasserstoffbrückenbindungsnetzwerkes. Die Magnetitoberfläche scheint hingegen eher träge gegenüber der CO2-Chemisorption zu sein. Bei niedrigen Temperaturen kann die Bildung schwacher chemisorbierter Spezies als durch Oberflächendefekte bedingt interpretiert werden. In jedem Fall spielt bei höheren Temperaturen das Vorhandensein von Wasser auf der regulären Oberfläche eine entscheidende Rolle in der CO2-Aktivierung und fördert die Bildung von Bikarbonat-Spezies. / The interaction of water and CO2 with oxide surfaces is nowadays a hot topic especially for environmental scientists. The use of water as hydrogen for CO2 reduction/hydrogenation would be the most ideal process, which would contribute to reduce CO2 emission into the atmosphere and minimize the dependence of society on fossil fuels. Despite certain advances in this field, further fundamental studies need to be addressed to understand the interaction of water and CO2 with metal-oxide surfaces for a rational design of heterogeneous catalytic processes. This work presents a fundamental study of the adsorption of water and CO2 on well-defined Fe3O4(111) films grown on Pt(111) single crystal. To understand the adsorption properties of the iron oxide film, the surface has been characterized using CO as probe molecule. The characterization showed that the magnetite surface is terminated by a 1/4 monolayer of tetrahedrally coordinated Fe3+ ions on top of a close-packed oxygen layer. On this well characterized surface, the interaction with water and CO2 has been investigated in detail. Combined IRAS and TPD data revealed that water readily dissociates on the surface, forming two hydroxyl species, OwH and OsH, involving oxygen atoms from the water (w) itself and from the oxide surface (s), respectively. At increasing coverage, these species act as anchors for molecular water adsorption ultimately giving rise to a long-range ordered architecture. DFT calculations rationalized these data in the framework of cooperative formation of the hydrogen bonding network. Moreover, Fe3O4(111) seems to be rather inert towards CO2 chemisorption at low temperatures, and the formation of weak chemisorbed species may be interpreted as driven by surface imperfections. At higher temperatures, the presence of water on the regular surface (induced and/or just as residual gas adsorption) plays a critical role in the CO2 activation, promoting the formation of bicarbonate-like species.

Superhydrophobic coatings (SHC) with excellent self-cleaning and corrosion resistance property is developed on magnetite coated AISI SAE 1020 steel by using a simple immersion method. Roughness measurement, scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), contact angle measurement (CAM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), potentiodynamic polarization test, electrochemical impedance spectroscopy (EIS), and qualitative characterization of self-cleaning behavior, antifouling property and durability of the coatings are assessed. A water contact angle as high as 152o on the coated surface with excellent self-cleaning and resistivity to corrosion and good longevity in atmospheric air is obtained. Self-cleaning test results prove that these surfaces can find applications in large scale production of engineering materials. Potentiodynamic polarization tests and EIS tests confirm that the superhydrophobic low carbon steel surfaces have better resistance to corrosion compared to bare steel and magnetite coated steel in 3.5% NaCl solution. But the longevity of the coated steel surfaces in 3.5% salt solution is limited, which is revealed by the immersion durability test. However, hydrophobic coatings (HC) have better stability in normal tap water, and it can stay unharmed up to 15 days. Finally, hydrophobic coatings on low carbon steel surface retains hydrophobic in open atmosphere for more than two months. Results of this investigation show surface roughness is a critical factor in manufacturing hydrophobic steel surfaces. Higher contact angles are obtained for rougher and more uniform surfaces. A linear mathematical relationship (y =6x+104; R2 = 0.93) is obtained between contact angle (y) and surface roughness (x).