Due to increasing atmospheric carbon dioxide (CO2) concentration, energy sources that release to the atmosphere smaller amounts of CO2 are of interest. Initially, all the efforts were focused on increasing the system efficiency, now more attention is being paid recently on capturing and sequestering CO2 from combustion process and eliminating discharge to the atmosphere from the major source points. In these circumstances, the chemical-looping combustion (CLC) is a promising concept that can be used in power generation which integrates power production and CO2 capture. The aim of this work is to study reaction kinetics of Chemical-Looping Combustion. In order to come up with a suitable reactor design we should have a good knowledge of the reaction kinetics happening in the air and fuel reactor; then, to get such an information as will be mentioned later, reactivity investigation was carried out in thermogravimetric analysis (TGA).

Pollution of water by herbicides and heavy metals has caused world wide concern because of the adverse effects of these pollutants on the environment, humans and wildlife. This has resulted in tighter legislation being imposed on the levels of these pollutants in drinking water. For example, the European Union (EU) has set the legislation in the drinking water Directive Admissible Concentration for a single herbicide to a maximum of 0.1 ppb. Despite the tight environmental pollution controls, isolated cases of pollutants exceeding their limits are still encountered. This would suggest that research towards the efficient and effective removal of these pollutants will be an on-going process. In this study, sorption of copper and some selected herbicides e.g. atrazine, benazolin and 2,4-dichlorophenoxyacetic acid (2,4-D) was undertaken on a conventional activated carbon and its modified series. A low level detection method was developed using High Performance Liquid Chromatography (HPLC) and this system was used to quantify the sorption capacity of the herbicides. In order to understand the sorption mechanism of the targeted pollutants, physical and chemical characterisation of the adsorbents was undertaken using a variety of techniques. These include, Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared (FT-IR) method, pore size distribution and surface area measurements, elemental analysis, sodium capacity determination, zeta potential and pH titration. The sorption data were presented and analysed by conventional adsorption isotherms. Sorption of the herbicides was favoured on carbon samples with least oxygen content while the uptake of copper was strongest in oxidised carbons. Kinetic experimental data were analysed by a pseudo second order model and the Boyd kinetic model. Molecular structural configurations and the physico-chemical properties of the adsorbent played a crucial role in the sorption behaviour of the herbicides.

La réponse globale de cellules animales à des contraintes hydrodynamiques lors de leur culture en suspension dans des réacteurs agités a été étudiée grâce à une approche intégrative couplant les outils du génie biochimique à ceux de la mécanique des fluides numérique. En premier lieu, la description de l’hydrodynamique moyenne et locale de deux systèmes de culture agités de laboratoire, spinner et bioréacteur, a été réalisée. Puis, l'étude des cinétiques macroscopiques de cellules CHO cultivées en suspension, en milieu sans sérum et sans protéine, a été réalisée avec différentes vitesses d’agitation, pour évaluer l'impact de l'agitation sur les vitesses de croissance et de mort cellulaires, ainsi que de consommation des substrats et de production des métabolites et de l'interféron-gamma recombinant. Des caractérisations supplémentaires des cellules (apoptose, protéines intracellulaires) et de l'interféron ont également été réalisées. Les effets de l'intensification de l'agitation ont été représentés avec plusieurs corrélations globales reliant : (i) en milieu contenant du pluronic, l'intégrale des cellules viables au nombre de Reynolds, et la proportion de cellules lysées à la valeur moyenne de l'énergie de dissipation, <[epsilon]? (ii) en milieu sans pluronic, les vitesses spécifiques de croissance et de mort cellulaires à <[epsilon]. De plus, l'analyse par CFD de la distribution spatio-temporelle des contraintes indique que la lyse cellulaire, observée dans le réacteur aux conditions extrêmes d'agitation, serait plutôt liée à des valeurs locales très élevées de [epsilon], ainsi qu’à la fréquence d'exposition des cellules dans ces zones énergétiques. Un modèle hydro-cinétique original, couplant l’hydrodynamique locale aux cinétiques cellulaires de croissance et de mort, et basé sur l’intermittence de la turbulence permet la prédiction de la lyse massive observée en réacteur sous certaines conditions. Pour confirmer le fait que les effets liés à l'intensification de l'agitation sont bien le résultat d'une augmentation des contraintes hydrodynamiques, et non d'une amélioration du transfert d'oxygène, ce dernier a été mesuré et modélisé par couplage avec une simulation numérique de type Volume Of Fluid , concluant en une absence de limitation d'oxygène. Enfin, la conception, le dimensionnement et la caractérisation hydrodynamique d'un réacteur innovant de type Couette-Taylor, sont proposées pour la mise en œuvre de cultures perfusées dans un environnement hydrodynamique mieux contrôlé / The global response of animal cells to hydrodynamic stress when cultivated in suspension in stirred tank reactors was studied. To do this, an integrative approach coupling biochemical engineering and fluid mechanics tools were used. First, the description of the global and local hydrodynamics of two bench-scale agitated reactors, a spinner flask and a bioreactor, was carried out. Then, macroscopic kinetics of CHO cells cultivated in a serum and protein-free medium were obtained at various agitation rates, in order to evaluate the impact of agitation on cellular growth and death, as well as substrates consumption and metabolites and recombining IFN-[gamma] production. IFN-[gamma] and cells physiological state were more precisely characterised by glycosylation, apoptosis state and intracellular proteins measurements. The effects of the agitation increase were represented by several global correlations that related: (i) in a medium containing Pluronic F68, the Integral of the Viable Cells Density to the Reynolds number, and the proportion of lysed cells with the average value of energy dissipation rate <[epsilon]? (ii) in a medium without pluronic, specific cell growth and death rates to <[epsilon]. Moreover, CFD analysis of the stress distribution indicated that the cellular lysis observed in the bioreactor at the highest agitation rate, would be related to very high local values of [epsilon], and to the exposure frequency of the cells in these energetic zones. An original hydro-kinetic model based on the intermittency of turbulence and coupling the local hydrodynamics with cell growth and death kinetics, allowed the prediction of the massive cell lysis observed in the bioreactor under some mixing conditions. To decouple shear stress effects from oxygen transfer improvement, the oxygen transfer coefficient was experimentally measured and modelled using a Volume Of Fluid numerical simulation. Our results indicated the absence of an oxygen limitation, which confirmed that this cell response resulted from the hydrodynamic stress increase alone. Lastly, an innovative continuous and perfused Couette-Taylor reactor, allowing a better-controlled hydrodynamic environment was designed and sized. Its hydrodynamic description was carried out using CFD calculations

In the modern practice, a sustainable development strategy in a domain of wasteutilization is shifting its focus from a general completeness of recycling to a morespecific attention to efficiently utilize elements in the wastes. This is well-illustrated bythe steelmaking slag industries. The major waste product from the steelmaking practiceis slag and its main constituents are: CaO, SiO2, Al2O3, MnO, FeO and so on. The mainfield of application for the steelmaking slags is civil engineering, especially for road andwaterway construction. However, a significant amount of the slag remains in the dumps,damaging the environment as well as requiring a land for secure storage. Efficientrecycling of these materials is of increasing interest worldwide as a result of increasingsustainability in processes with respect to increasing raw material costs and wastereduction.In order to find a practical solution, joint efforts are currently made at the RoyalInstitute of Technology, Sweden and National Metallurgical Academy of Ukraine. Theconcept is based on transformation of non-magnetic wüstite (FeO) to magneticmagnetite (Fe3O4) using an oxidizing atmosphere was proposed.In order to verify the feasibility of the proposed way of slag utilization, experiments onthe ternary CaO-FeO-SiO2 and quaternary CaO-FeO-SiO2-MnO slags systems,accompanied by thermodynamic and kinetic modelling, were performed. The crystalprecipitation during synthetic slag oxidation was observed by Confocal Scanning LaserMicroscopy (CSLM). Precipitated phases were found to be magnetite and manganeseferrite in the spinel form.Obtained magnetite and manganese ferrite can be separated from the slag by magneticseparation.The formation of nanosize manganese ferrite from the CaO-FeO-SiO2-MnO slag systemduring oxidation was investigated. Experiments were conducted in a horizontalresistance furnace in an oxidizing atmosphere (air). The final product was analysed by Xraydiffraction (XRD). The particles size of the manganese ferrite was estimated by theScherrer formula and was found to be of the order of 23-25 nm. In order to get anunderstanding of the magnetic properties of the manganese ferrite recovered from slagtreatment, it was necessary to synthesize a reference compound from pure precursors.The MnFe2O4 nanopowder was synthesized by the oxalate route. The size effects on themagnetic properties of manganese ferrite particles were investigated.IIThe potential way of the magnetite particles separation from liquid slags was investigatedby cold model studies. The experimental technique of mobilising non-conducting,nonmagnetic particles in conducting liquid in crossed electric and magnetic fields wasinvestigated in order to find the way of the particle separation from the liquidsteelmaking slags. The effects of the current density, magnetic field, size and shape ofthe particle on the particle velocity under action of the electromagnetic buoyancy force(EBF) in the electrolyte were analyzed. / QC 20100916