Carbon dioxide emissions to the atmosphere today cause problems around the world. In Sweden, the steel production contributes significantly to carbon dioxide emissions. The steel industry challenge is to improve the metallurgical processes to decrease the carbon dioxide emissions. One way to reduce the emissions is to use renewable carbon sources. The blast furnace process is a counter current reduction process for ironmaking. Raw materials such as iron ore agglomerates, coke and slag formers are charged at the top of the furnace while oxygen-rich blast air and powdered coal are injected in the bottom. The gases produced by combustion rise through the burden on the top of the furnace. The combustion of carbon produces carbon monoxide which is the reducing gas used for the reduction of iron oxides to pig iron. The process is the highest producer of CO2 emissions in Sweden; biomass can partially replace fossil carbon in coal blends for cokemaking, coal powder for coal injection and coke in self-reducing briquettes.  The purpose of this project was to maximize the addition of biomass in coal blends for cokemaking and the addition in briquettes produced for the recovery of iron bearing rest products. The challenge with biomass in cokemaking is its low density and high reactivity which decrease the coke yield and coke strength at the same time that it increases the coke reactivity. The coke quality has to be kept at sufficient quality in order to avoid effects on productivity and process stability in the blast furnace. The addition of biomass in briquettes is limited due to the low density of the biomass which may affect the strength of the briquettes. The effect of the addition of sawdust in coke and briquettes has been studied to understand the effect on reaction behaviour of bio-coal. Heat-treatment of sawdust with high volatile coal was performed in order to achieve a coating of coal on the sawdust surface and get less reactive sawdust. Torrefied sawdust contained 23 wt. % fixed carbon while the pre-treatment of sawdust with high volatile coal increased the content to about 60 wt. %. Pre-treated sawdust was added to coal blend for coke making and briquettes containing iron oxide. The pre-treated sawdust was added to five coal blends for coke production, the contents were 5, 10 and 20 wt. %, and a base blend was used as reference. Coke reactivity, chemical composition and cold compression strength in coke were studied. This work resulted in an improved bulk density; up to 20 wt. % pre-treated sawdust could be added to the coal blend and still keep a bulk density of 800 kg/m3. The coke yields in cokes with pre-treated sawdust were comparable to the coke reference. The temperature at which carbon in coke began to be consumed was slightly higher in coke containing sawdust treated with 50 wt. % high volatile coal. It was estimated that the CO2 emission from fossil coal could be reduced with 8.6 % per ton hot metal (THM) with the addition of 10 wt. % pre-treated sawdust to coal blends for cokemaking. The addition of 20 wt. % pre-treated sawdust could reduce the CO2 emission with 10% per THM. In addition, two different mixes of briquettes were produced, one with torrefied sawdust and one with pre-treated sawdust. The chemical composition and reduction of iron oxides in briquettes was also studied and evaluated. Briquettes with treated sawdust were more compact, i.e. had a higher density than briquettes containing torrefied sawdust. The amount of hematite that could be added to the briquette mixes was 0.107 moles in briquettes with torrefied sawdust and 0.112 moles in briquettes with pre-treated torrefied sawdust. / Koldioxidutsläppet till atmosfären orsakar idag problem runt om i världen. I Sverige bidrar stålproduktionen avsevärt till koldioxidutsläppet. Stålindustrin har som en utmaning att förbättra de metallurgiska processerna för att sänka utsläppet av koldioxid. Ett sätt att sänka koldioxidutsläppen är att minska påverkan genom att använda förnybara kolkällor. Masugnsprocessen är en kontinuerlig reduktionsprocess för råjärnframställning och en av processerna där det används reduktionsmedel från fossila kolkällor. Råmaterial som järnmalm, koks och slaggformare chargeras på toppen av ugnen medan syrgasberikad blästerluft och pulveriserat kol injiceras i botten av ugnen genom masugnens formor. De gaser som produceras vid förbränning stiger upp genom beskickningen upp till ugnens topp. Vid förgasning av kol bildas kolmonoxid som är den reducerande gasen, den möjliggör reduktionen av järnoxider vid framställning av råjärn. Torrefierad biomassa kan delvis ersätta fossilt kol i kolblandningarna för kokstillverkning, i kolinjektionen och i briketter. Syftet med detta projekt var att maximera mängden tillsatt biomassa i kolblandningarna för kokstillverkning och i briketter för återvinning av järnbärande restprodukter. Utmaningen med biomassa i kokstillverkningen är den höga reaktiviteten och den låga densiteten av kol, vilket resulterar i låg koksutbyte när den tillsätts i kolblandningar. Biomassa innehåller också en högt halt flyktiga ämnen vilket resulterar i koks med låg hållfasthet och hög reaktivitet. Kokskvalitén måste behållas för att undvika processvariationer i masugnen. Tillsatsen av biomassa i briketter, är begränsat då biomassa kan påverka briketternas hållfasthet. Effekten av tillsatsen av biomassa i koks och briketter har studerats för att kunna förstå reaktionsbeteendet i dessa när torrefied sågspån och förbehandlat sågspån med hög fluiditetskol har tillsatts till blandningarna. Värmebehandling av torrifierat sågspån med en hög fluiditeteskol gjordes för att uppnå en mindre reaktiv biomassa. Torrifierat sågspån innehöll 22.9 viktsprocent kol, förbehandlingen av sågspån med hög fluiditetskol ökade halten till cirka 60 viktsprocent. Den behandlade sågspånen tillsattes till fem kolblandningar för koksframställning, 5, 10 och 20 viktprocent tillsattes till en bas blandning som användes referens. Koksreaktiviteten, kemisk sammansättning och hållfasthet i koks studerades. Arbetet resulterade i en förbättrad bulkdensitet då upp till 20 viktprocent förbehandlad biomassa kunde tillsättas i kolblandningen och fortfarande behålla en bulkdensitet på 800 kg/m3. Koksutbytet i alla koks med förbehandlat sågspån var jämförbart med koksreferensen. Temperaturen där kemisk kol i koks började förbrukas, var något högre i koks som innehöll sågspån med 50 viktsprocent hög fluiditetskol. Koldioxidutsläppen från fossilt kol per ton råjärn (THM) uppskattades att vara 8,6 % lägre med tillsatsen av 10 viktprocent förbehandlat sågspån i kolblandningar för kokstillverkning. Tillsatsen av 20 viktprocent skulle innebära en minskning på 10 % per ton råjärn. Briketter med två olika blandningar framställdes, en blandning med torrifierat sågspån och en blandning med behandlat sågspån. Briketterna karakteriserades genom att analysera den kemiska sammansättningen och reduktionen av järnoxider i termisk reducerade briketter. Briketter med behandlat sågspån var mer kompakta, d.v.s. hade en högre densitet än briketter som innehöll torrifierad sågspån. Mängden hematit som kunde tillsättas i mixen med torrifierad sågspån var 0.107 mol, medan i mixen med förbehandlat sågspån 0.112 mol kunde tillsättas. / Bio4metals / CAMM

Táto diplomová práca sa zaoberá štúdiom alfa-Fe2O3(012) vystaveného vodnému prostrediu. Súčasný stav poznania ohľadom oxidov železa s pozornosťou vkladanou do popisu alfa-Fe2O3 a jeho (012) povrchu je stručne zhrnutá. Experimentálná časť tejto práce začína s popisom unikátného zariadenia na depozíciu kvapalnej vody na povrchy monokryštalických vzoriek compatibilného s podmienkami ultra vysokého vákuua. Jednotlivé konštrukčné časti a detaily sú diskutované. Navrhnutý systém bol testovaný na vzorkách striebornej fólie a monokryštálu Fe3O4 s povrchovom v rovine [100]. Chemické zloženie a morfológia povrchu po experimente s kvapalnou vodou je diskutovaná. Navrhnuté zariadenie bolo použité na štúdium interakcie vody so známymi (1x1) a (2x1) povrchovými alfa-Fe2O3(012). Experimentálne dáta ukazujú, že voda sa viaže na obe reconštrukcie disociatívne s určitým množstvom molekulárnej vody naviazanej na adsorbované hydroxydi. (1x1) sa zdá javý stabilná po expozícii rôznym tlakom vodnej pary, zatial čo (2x1) vykazuje zmenu na (1x1) pri expozíciach vyšším tlakom vodnej pary alebo po niekolo minútovej expozíci electrónovému zväzku. Ďalej sú v tejto práci prezentované prvé výsledky z štúdie prechodu (1x1) rekonštrukcie na (2x1) pomocou mikroskpie nízkoenergiových elektrónov. Výsledky ukazujú, že táto premena na nižších teplotách je inciovaná na hranách atomárnych vrstiev a defektov na povrchu, ktorá potom postupuje smerom k stredu atomárnych terás. Meranie na vyšších teplotách vykazuje postupnú premenu povrchu naznačúju viaceru nukleačných centrech z ktorých sa (2x1) povrch širi ďalej.

This thesis deals with the combined ultra-high vacuum (UHV) and electrochemical (EC) studies of selected iron oxide surfaces, namely Fe3O4(001) and -Fe2O3(012). The state-of- the-art knowledge regarding these surfaces is briefly reviewed, and importance of understanding these materials in the electrochemical environment is discussed. The design of the transfer system between UHV and EC environment is presented; individual features of the system are thoroughly discussed and the system is used for testing the stability of the Fe3O4(001) (2×2)R45° surface reconstruction in ambient conditions. The experimental results presented in this thesis show that the Fe3O4(001) (2×2)R45° reconstruction, utilized as an adatom array for single atom catalysis studies, survives both exposure to air and to liquid water, if the exposure is achieved in well-controlled fashion. Further, this thesis presents the first-ever atomic scale scanning tunneling microscopy (STM) study of the -Fe2O3(012) surface, which is important for photoelectrochemical water splitting. STM images of two surface reconstructions of the -Fe2O3(012) surface known to date are presented. A bulk terminated model of the (1×1) reconstruction is confirmed and a novel surface structure model for the (2×1) reconstructed surface is proposed. Adsorption studies of H2O and O2 on the (2×1) reconstructed surface are documented by timelapse STM.

M.Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology. / Several industries utilize species of synthetic dyes that are found in their wastewater, which is passed out in the environment. Methylene blue is one of the organic dyes that causes water pollution. It causes damage to the aquatic eco-system and health problems to human beings. It is non-biodegradable due to its chemical nature. Advanced oxidation processes (AOP’s) have been developed for the degradation of these dyes, however, some of these methods are limited due to their high cost and low efficiency. Among these methods, Fenton catalysis has been proven to be an effective method due to its low cost, high efficiency, and re-usability. Iron oxide nanoparticles have been mainly used in Fenton process however they are also limitated due to the forming of secondary pollutants, due to catalysts recovery difficulties, hence they require supporting materials. In this work, iron oxide-based catalyst supported on silica nanofibers were fabricated via electrospinning of silica sol incorporated with iron oxide, using three different routes, (a) Method 1 - wetness incipient impregnation, (b) Method 2 - direct addition of iron precursor to the silica sol and (c) Method 3 - incorporation of iron oxide nanoparticles into silica sol. The effect of iron oxide concentration loadings (1 wt%, 2 wt% and 5 wt %) was studied. Increase in iron content resulted in agglomeration of nanoparticles as embedded in the fibers as evident from their SEM images in method 3.1. The SEM results showed diameters from method 1, 2 and 3 ranging from the distribution ranges of 276 – 288 nm, 243 – 265 nm and 188 nm, respectively. EDS showed the presences of Si, P, Fe, O and P. XRD showed a crystalline phase of magnetite (9 nm) and goethite (32 nm) method 1 and 3, with vibrational modes at 3300 cm-1, 1100 cm-1, 950 cm-1 and 580 cm-1 ascribed to O-H, Si-O-Si, Si-O and Fe-O on the FTIR spectra, it showed both the presence of silica and iron oxide. The degradation of methylene blue was monitored by UV-Vis spectroscopy, the Fenton catalytic activity of the iron-oxide supported on silica nanofibers showed higher catalytic activity compared to the unsupported iron-oxide nanoparticles. The catalyst prepared by wetness incipient impregnation (method 1) had a degradation efficiency of 69.1%, the direct addition of iron precursor to the silica sol (method 2) had 75.2% and incorporation of iron oxide nanoparticles magnetite and goethite with the silica sol had 53.7% and 34.7%, respectively. The catalyst prepared by the direct addition of iron precursor in the sol (method 2) showed a high catalytic activity compared to the other catalyst prepared by other methods. Unsupported Iron oxide nanoparticles had a higher degree of leaching of 1.28 ppm magnetite, and 1.68 ppm goethite, compared to the supported iron oxide in method 1 and method 3. The catalyst incorporated with goethite showed a high degree of leaching, 3.95 ppm and 1.33 ppm. The catalyst with high catalytic activity showed a lower degree of leaching with 0.05 ppm.

No description available.

No description available.

Ziel der Untersuchungen war es, neue Strategien zu entwickeln, die zu einer Verbesserung der MR-Diagnostik von Gliomen führen. Im Vordergrund des Interesses stand dabei die MR-Charakterisierung von experimentellen Gliomen mittels superparamagnetischer Eisenoxide, wobei MION ("Monocrystalline-Iron-Oxide-Nanopartikel") als Modellsubstanz für einen Großteil der Untersuchungen benutzt wurde. In Experimenten zur Blut-Hirn-Schranke (BHS) wurde gezeigt, dass normales Hirngewebe jenseits der BHS mit Eisenoxiden erreicht werden kann, wenn artifiziell die BHS zuvor hyperosmotisch durch Mannitol-Infusion temporär geöffnet wurde. Neben der intrazellulären Aufnahme in Astrozyten werden Eisenoxide nach erfolgter BHS-Öffnung in signifikant höherem Maße von aktivierter Mikroglia phagozytiert. Nach selektiver Öffnung der BHS durch Bradykinin-Injektion in die A. carotis interna lässt sich selektiv der Transport von Eisenoxiden in das Gliomzentrum vergrößern. Am experimentellen Gliommodell ließ sich zeigen, dass intravenöse MION-Gabe zu einem charakteristischen ringförmigen Erscheinungsbild in der MRT der großen Tumoren führt: Die histologischen Untersuchungen bei mehreren Gliomarten (C6 und 9L) zeigen eindeutig die Phagozytose von Eisenpartikeln durch Gliomzellen selbst. Verglichen mit der Eisenoxid-Aufnahme in die Gliomzelle ist die Phagozytose der Eisenpartikel durch ortsständige Mikrogliazellen und Blutmakrophagen jedoch signifikant größer. Die intrazelluläre Aufnahme von MION durch Tumorzellen lies sich in Zellkulturexperimenten an verschiedenen Gliom- (C6, 9L) und Karzinom-Zelllinien (LX-1) bestätigen. In vitro konnte gezeigt werden dass die Konjugation von Transferrin (Tf) an eine Eisenoxidverbindung zu einer verstärkten intrazelluläre Aufnahme verglichen mit unkonjugiertem Verbindungen führt. Die Untersuchungen zur Bildgebung der Tumorvaskularisation von experimentellen Gliomen ergaben, dass durch die kombinatorische Anwendung eines kleinmolekularen und eines großmolekularen Markers mit anschließender einfacher Bildsubtraktion die vaskulären und interstitiellen Volumenfraktionen (VVF, IVF) ermittelt werden können. Auch die alleinige Injektion der noch experimentellen Blut-Pool-Marker MPEG-Pl-GdDTPA und Gadomer-17 ermöglicht im Tiermodell die quantitative Bestimmung sowohl des vaskulären Volumens (CBV) als auch der Permeabilität (P). Bei den Eisenoxiden verfälschen deren starke Suszeptibilitätseffekte die quantitative Bestimmung von Blutflussdaten, auch die Quantifizierung der Gefäßpermeabilität ist mit diesen Verbindungen mittels dynanischer MRT nicht möglich. / The aim of the studies was to develop new strategies for improving magnetic resonance imaging (MRI) of gliomas. In the majority of experiments the focus was on the characterization of experimental gliomas after administration of superparamagnetic iron oxides using MION (Monocrystalline Iron Oxide Nanoparticles) as a model compound. Experiments on the blood-brain barrier (BBB) demonstrated that iron oxides reach normal brain tissue beyond the BBB after their artificial, transient hyperosmotic opening by mannitol infusion. Upon opening of the BBB, iron oxides not only show intracellular uptake by astrocytes but are also phagocytosed in significantly higher amounts by activated microglia. Selective opening of the BBB by bradykinin injection into the internal carotid artery specifically increases the transport of iron oxides into the center of gliomas. Using an experimental glioma model, it was shown that intravenous administration of MION produces a characteristic ring enhancement of large tumors on MR images. Histologic studies of different types of gliomas (C6 and 9L) unequivocally demonstrated that iron oxide particles were phagocytosed by the glioma cells themselves. However, iron oxide uptake by glioma cells is significantly less pronounced compared to the phagocytosis of iron oxide particles by local microglial cells and blood macrophages. The incorporation of MION by tumor cells was confirmed in cell culture experiments using different glioma (C6, 9L) and carcinoma cell lines (LX-1). In vitro studies showed that conjugation of transferrin to an iron oxide compound enhanced intracellular uptake compared to unconjugated compounds. The imaging studies investigating tumor vascularization in experimental gliomas demonstrated that the combined use of a small-molecular and a large-molecular marker and simple image subtraction allow for determining vascular and interstitial volume fractions (VVF, IVF). Furthermore, injection of the blood pool markers MPEG-P1-Gd-DTPA and gadomer-17 alone likewise enables quantitative determination of both vascular volume (CBV) and permeability (P) in the animal model. Iron oxide particles, on the other hand, have pronounced susceptibility effects, which impair the quantitative determination of blood flow data. Nor do the particles allow for quantifying vascular permeability by dynamic MR imaging.

Ce travail s’inscrit dans une problématique locale de teneur élevée en arsenic naturel dans le but d’améliorer la surveillance et la gestion de la qualité de la ressource en eau dans l’arrière-pays niçois. L’existence de grandes disparités géographiques des teneurs en arsenic font de la géologie la cause principale de cette contamination. L’intérêt de ce travail est d’appréhender les interactions solide/solution entre l’arsenic total dissous et les particules solides (matières en suspensions, sédiment de lit de rivière, solides naturels). Pour décrypter le comportement géochimique de l’arsenic, les trois objectifs principaux sont : de déterminer son état de conservativité dans le milieu naturel ; puis d’étudier les phénomènes d’adsorption en laboratoire sur des solides naturels (illite, oxydes de fer) ou de référence (kaolinite) ; puis enfin d’apporter une application directe au piégeage de l’arsenic par la création d’un pilote de traitement destiné à dépolluer une source d’eau destiné à la consommation humaine. La concentration en particule est le facteur influençant la conservativité de l’arsenic dans le système de confluence Tinée/Var selon les données des compartiments dissous et particulaire. La fraction colloïdale semble avoir une implication de premier ordre lors de la période de crue étudiée. Le piégeage de l’arsenic est favorisé par les oxyhydroxydes de fer, les argiles puis en moindre quantité par les solides acido-solubles. / This work aimed to solve a local problem of high water contamination with natural arsenic. In order to monitor and manage the water resource quality in French Riviera region. The different geographical repartition of arsenic content makes the consequences of this contamination to the geology. The interest of this work is to understand the interaction at solid/liquid interfaces between total dissolved arsenic and the solid particles (suspended particles matter, bed sediments and natural solids). To elucidate the geochemical behavior of arsenic, the three main objectives are: to determine the conservative states in the natural environment, then to study the adsorption phenomena under laboratory conditions onto the natural solids (illite and iron oxides) or reference materials (kaolinite); thirdly to apply the outcome of this work to establish a processing pilot for arsenic removal to decontaminate drinking water. The particle content is the main factor which influences the conservativity of arsenic in the confluence Tinée/Var. Colloids seems to have the main role in the arsenic removal in the studied flood period. Arsenic removal is favored by iron oxides, and clays, but less efficiently by acid-soluble compounds. The study of sorption mechanisms onto clays showed that adsorption of arsenic is strongly dependent on pH, quantity of aluminol reactive sites, influence of competitive anions such as carbonates and phosphates. Finally, the association of zeolites (high specific surface area) with coating of amorphous iron oxides (high affinity for arsenic) makes this adsorbent the most efficient, hence was studied and used in this work for arsenic adsorption.

Le phytomanagement de matrices contaminées en métaux couple leur réhabilitation écologique avec la production de biomasses végétales pour la bioéconomie. Un front de science est d’identifier des assemblages végétaux et d’optimiser leur production, aidée ou non par l’ajout d’amendements. Le phytomanagement de deux sols, l’un contaminé en Cu, l’autre en Cd, Pb et Zn, a été testé en conditions contrôlées. L’emploi conjoint de biochar et de grenaille d’acier diminue la phytotoxicité des 2 sols. En pots, sur 2 ans, cette combinaison d’amendements séquestre du carbone, diminue la phytotoxicité du sol contaminé en Cu et produit une biomasse d’Arundo donax L. et de Populus nigra L. non contaminée, utilisable par le secteur de l’énergie. Ces modalités de culture et d’amendement ont été installées pour un suivi à long terme sur le site contaminé en Cu. Parallèlement, en microcosmes, parmi 4 macrophytes utilisées en zone humide construite (CW) pour décontaminer des matrices aqueuses (i.e. Arundo donax L., Cyperus eragrostis Lam., Iris pseudacorus L. et Phalaris arundinacea L.), A. donax est la mieux adaptée pour fournir des racines à forte concentration en Cu utilisables pour produire un écocatalyseur riche en Cu. Le phytomanagement d’un effluent de bouillie bordelaise (EB, 69 μM Cu) par A. donax a été testé en CW pilote. Il est décontaminé en 48h, sa concentration en Cu respectant la réglementation du rejet d’effluent en réseau d'assainissement. Cependant, après un cycle de circulation, la concentration en Cu des racines d’A. donax (623 ± 140 mg Cu kg-1) est inférieure aux besoins de l’éco-catalyse, et le cycle serait à répéter pour atteindre les 1000 mg Cu kg-1 requis. / The phytomanagement of metal-contaminated matrices (soils and water) combines their ecological remediation and the production of non-food crops for the bioeconomy. One science frontier is to identify plant assemblage and to optimize their biomass production, aided or not by amendment addition and cultural practices. A Cu-contaminated soil and a Cd/Pb/Zn-contaminated one were phytomanaged in controlled conditions. The combination of biochar and iron grit reduced the phytotoxicity in both soils. In a 2-year pot experiment, this amendment combination decreased the phytotoxicity of the Cu-contaminated soil, enhanced soil C sequestration and produced an uncontaminated biomass of Arundo donax L. and Populus nigra L. adapted for bioenergy production. These combinations of culture and amendment are tested in field trial at the Cu-contaminated site. In parallel, in microcosm experiment, out of 4 macrophytes commonly used in constructed wetlands (CW) to clean up aqueous matrices (i.e. Arundo donax L., Cyperus eragrostis Lam., Iris pseudacorus L. and Phalaris arundinacea L.), A. donax was the best adapted to produce a high Cu-rich root mat potentially usable as Cu-ecocatalyst. Clean up of a Bordeaux mixture effluent (BME, 69 μM Cu) by A. donax was tested in a pilot-scale CW. The BME was decontaminated in 48 hours, its Cu concentration being in compliance for indirect discharge of chemical industry effluents. However, after one BME circulation cycle, root Cu concentration of A. donax roots (623 ± 140 mg kg-1) was lower than threshold value for Cu-ecocatalysts (1000 mg kg-1) and successive treatments must be repeated to achieve required Cu concentration.

No description available.