Search results for "Oxydation"

Designing biochar properties through the blending of biomass feedstock with metals: Impact on oxyanions adsorption behavior

2018

Metal-blending of biomass prior to pyrolysis is investigated in this work as a tool to modify biochar physico-chemical properties and its behavior as adsorbent. Six different compounds were used for metal-blending: AlCl3, Cu(OH)2, FeSO4, KCl, MgCl2 and Mg(OH)2. Pyrolysis experiments were performed at 400 and 700 °C and the characterization of biochar properties included: elemental composition, thermal stability, surface area and pore size distribution, Zeta potential, redox potential, chemical structure (with nuclear magnetic resonance) and adsorption behavior of arsenate, phosphate and nitrate. Metalblending strongly affected biochars' surface charge and redox potential. Moreover, it incre…

Modeling of Electrochemical Process for Water Treatment Using Diamond Films

2011

Adsorption and diffusion study, in gazeous phase, of wine active molecules in cork

2010

During wine ageing, oxidation reactions occur and can lead to wine sensory defaults. The main factors involved in this phenomenon are oxygen and gas barrier properties of stoppers. During the last ten years, some studies investigated oxygen transfer during winemaking and wine storage. However, only few of them deal with the interactions between molecules and sealing materials. The material studied in this work is raw cork, without any treatment, neither washed nor surface treated (with paraffin or silicone). This Phd work focuses on mass transfer of some wine active molecules, in gas phase, through the cork. The selected molecules are water, ethanol, sulphur dioxide and oxygen. An adsorptio…

Wine metabolomic analysis : "chemical messages in a bottle"

2014

The main objective of this work was to develop non-targeted metabolomics analyses of bottled wines in order to decipher chemical informations from the time-related evolution of their composition. This original research was based on the hypothesis that, when analyzed, bottled wines would still hold chemical memories of envionmental parameters (vineyard management, oenological practices, climate, terroir…) at the moment of their elaboration, even after several years of ageing. A second hypothesis was that in order to anticipate the future evolution of the wine quality in terms of chemical composition, it is necessary to know what it was in the past. To that purpose, and for the first time in …

Influence of the Substituent on Selective Photocatalytic Oxidation of Aromatic Compounds in Aqueous TiO2 Suspensions.

2006

Experimental results are reported showing that the photocatalytic oxidation of aromatic compounds containing an electron-donor group (EDG) gives rise mainly to ortho- and para-monohydroxy derivatives while in the presence of an electron-withdrawing group (EWG) all the monohydroxy derivatives are obtained.

Synthesis and Characterization of TiO2 Based Inorganic-Organic Hybrid Photocatalysts for Enhancing the Selective Formation of 4-Methoxy-benzaldehyde …

2015

The oxidation of alcohols to carbonyl compounds in a clean fashion (i.e., with water as a solvent or under solvent-free conditions, and using O2 or H2O2 as the primary oxidant) is the subject of considerable research efforts. A new approach for the selective oxidation of soluble aromatic alcohols in water under mild conditions via a novel composite photocatalyst has been developed. The catalyst is synthesized by grafting 4-(4-(4- hydroxyphenylimino)cyclohexa-2,5dienylideneamino)phenol and silver nanoparticles onto the surface of moderately crystalline titanium dioxide. The titanium dioxide-based composite was first extensively characterized and then employed in the catalytic oxidation of 4-…

Efficacity of SMAT and laser shock-peening process for enhancement of titanium alloys high temperature oxidation resistance

2017

The aim of this thesis is to determine the influence of two mechanical surface treatments, the shot- peening performed with several type of balls (WC, alumina and glass) and the laser shock peening, on the high temperature oxidation resistance of two titanium alloys : alpha alloy with commercially purity (Grade 1) and aeronautical beta metastable alloy (TIMETAL-21S).After different treatments, the pieces are oxidized with different conditions: of time (between 5 hours to study the firsts times of oxidation and 3000 hours to compare with a classical aeronautical test), of temperature (600°C to 700°C) and atmosphere (dry air or oxygen).The pieces are analyzed before and after oxidation exposu…

Aroma production by solid state fermentation

2018

The adaptation of the production of γ-decalactones from submerged fermentation (SmF) to solid state fermentation (SSF) by Yarrowia lipolytica was investigated in this work. First of all, different solid matrices (corncob, cellulose sponge, luffa sponge, and castor seeds) were used for the first adaptation of the production of γ-décalactones. Luffa sponge appeared to be the most interesting solid support on which lactones were produced in higher concentrations than in the other solid matrices used. Then, the production of lactones using luffa sponge as the solid support was carried out in three types of SSF reactors to monitor different aeration conditions (without aeration, with a static ae…

Study of the fuel/clad bonding of pressurized water reactors fuel rods

2017

Durability and integrity of materials used in nuclear power plants is a continuous concern of the nuclear power plant owners and developers. During the fuel irradiation in pressurised water reactors (PWR), the whole fuel-clad assembly is subjected to several irradiation-induced modifications. In particular, the fuel element expansion concomitant to the cladding creeping, leads to the contacting of both materials, allowing the oxidation of the inner side of the clad, locally at first, then tending to affect the overall cladding inner surface. At high burnup, a bonding of the fuel periphery with the metallic cladding can be observed, forming the fuel-clad bonding phenomenon, which conditions …

Interconnecteurs métalliques de piles à combustibles de type SOFC : effet d'un traitement de surface par MOCVD.

2007

Les performances des alliages chromino-formeurs, utilisés comme interconnecteurs de piles à combustibles sont limitées par la formation d'une couche de chromine qui a une conductivité électrique faible et par la volatilisation des oxydes de chrome qui polluent la pile, et par conséquent détériorent son comportement. La réalisation d'une couche nanométrique d'oxydes d'éléments réactifs (La2O3, Y2O3, Nd2O3) par MOCVD permet d'améliorer la résistance à la corrosion à 800°C des alliages chromino-formeurs. Ces revêtements ont été réalisés sur l'alliage Crofer22APU dans le but de former des oxydes de type pérovskite tels que LaCrO3, NdCrO3 et YCrO3 lors de l'oxydation et qui possèdent une meilleu…