Letteratura scientifica selezionata sul tema "Ammoniac – Propriétés physico-chimiques"
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Articoli di riviste sul tema "Ammoniac – Propriétés physico-chimiques"
LEBRE, S., G. DAVID, C. NEGRELL, H. CARRERE, A. BATTIMELLI, E. RUIZ, L. VACHOUD e C. WISNIEWSKI. "Optimisation de la séparation de phases de digestat par un coagulant-floculant biosource". Techniques Sciences Méthodes 4 (20 aprile 2023): 21–31. http://dx.doi.org/10.36904/202304021.
Testo completoTesi sul tema "Ammoniac – Propriétés physico-chimiques"
Rizk-Ouaini, Rosette. "Contribution à l'étude des propriétés physicochimiques des haloamines et de leur réactivité sur l'ammoniac et les amines en milieu aqueux". Lyon 1, 1987. http://www.theses.fr/1987LYO19007.
Testo completoAvice, Jérémy. "Etudes des propriétés physico-chimiques de revêtements sol-gel par spectroscopie, optoacoustique et endommagement laser". Thesis, Le Mans, 2018. http://www.theses.fr/2018LEMA1028.
Testo completoWithin the framework of the simulation project, the Atomic Energy Commission (CEA) aims to reproduce the pressure and temperature conditions of a thermonuclear fusion with the Megajoule laser (LMJ). Some of the optical components of the LMJ, in particular some focusing lenses, are coated with an antireflective (AR) layer made by a sol-gel process. These films are composed of silica nanoparticles 10 nm in diameter with 55% porosity. To increase the mechanical strength of these layers, the films are exposed to water and ammonia vapors during a post-process. This post-treatment creates covalent bonds between the silica nanoparticles and thus strengthens the colloidal film. In order to give all the qualities of an optical coating, besides the key optical properties, we have set ourselves the objective of understanding the mechanical stability of these nanomaterials. In particular, we wanted, in the context of this thesis, to have a better understanding of the ammonia hardening process and for that we undertook a complete study of the physical and chemical parameters that govern the elasticity of this assembly of nanoparticles. In a second step, we highlighted the appearance of surface cracking causing optical diffusion and a decrease in mechanical reinforcement during the post-process. In order to minimize or even eliminate these surface cracks, we performed a parametric study to identify the elements responsible for this cracking
Pelé, Ronan. "Potentiel de l'ammoniac comme additif à l'éthanol pour les moteurs à allumage commandé". Electronic Thesis or Diss., Orléans, 2023. http://www.theses.fr/2023ORLE1035.
Testo completoDecarbonization of all forms of energy is urgent to mitigate climate change. Ammonia produced from renewable energies is not only an energy vector but also a potential carbon-free fuel in its structure for all thermal applications (gas turbine, ovens, and engines). Its less reactive combustion than traditional fuels can be improved with the addition of a more reactive and carbon neutral fuel, such as hydrogen, and biofuels, such as bio-ethanol. The objective of this thesis work is therefore to evaluate the potential of ammonia/ethanol mixtures from the injection and combustion process to the efficiency and pollutant emitted in the case of a spark ignition engine. A first part is devoted to the thermodynamics of mixtures of ammonia and ethanol. It has been shown that these two molecules, which are completely miscible with each other, can be injected in liquid form and mixed in the combustion chamber. The characterization of the liquid spray, in the second part, made it possible to highlight their radically different morphology from sprays of pure ethanol, and of gasoline as a reference. The strong vaporization of ammonia causes a very strong drop in temperature (down to -40/-60°C) which makes the spray thinner and longer. This very different geometry affects the local air/fuel mixture in the combustion chamber, affecting the process of initiation and development of combustion and the formation of pollutants. Laminar flame speed is one of the key fundamental parameters for thermal applications and simulations. It was characterized in a third part for the different mixtures. A small addition of ethanol greatly improves combustion, comparisons with current kinetic mechanisms have also been carried out in order to show the various research still necessary. The last part was devoted to the engine application: good performance and stability of these mixtures was obtained, making these mixtures good candidates for decarbonizing transport and electricity production by generator. Measurements of exhaust pollutant emissions have shown that adding ethanol to ammonia makes it possible to limit the release of unburned ammonia as well as N2O, a gas with a strong impact on global warming. However, NOx and CO emissions do not evolve monotonically with the addition of ethanol and a maximum was obtained around 50/50, showing the limit of these mixtures
Oumar, Mamadou. "Synthèse de tensioactifs hautement fluorés monocéphales et gemini et étude de leurs propriétés physico-chimiques en milieu aqueux". Nice, 2011. http://www.theses.fr/2011NICE4099.
Testo completoIn this work, we were interested in the synthesis and the evaluation of the physicochemical properties of highly fluorinated surfactants able to form molecular organized system in aqueous solution (aggregates). The intermediates, 2-[F-alkylethylthio]-N,N-dimethylethanamines synthesized are of major importance in the aim to obtain, in few steps, surfactants with easily changeable molecular parameters. The objective of this work was first to synthesize two families of quaternary ammonium type surfactants : bitail hybrid and Gemini (quaternary bisammoniums) surfactants as well as to evaluate the influence of the structural parameters (the spacer, the fluorinated chain and the hydrocarbon chain) on the physiochemical properties of these compounds. Then we have tested their capacity to form aggregates in solution beyond the critical aggregation concentration (CAC) or critical micellar concentration (CMC) if the formed aggregates are micelles. The evaluation of the surface-active properties to the air/water interface of these substances by the determination of the surface tension (γs), the crucial micellar concentration (CMC) and the energy of micellization (∆G°M) shows that these molecules are more efficient than their hydrocarbon counterparts described in the literature and that they can form aggregates at relatively weak concentrations. The study of the size of these aggregates by Dynamic Light Scattering (DLS), shows the presence of giant aggregates which is confirmed by the study in scanning electronic microscopy (SEM). This technique (SEM), allowed us to show the presence of giant aggregates which can play an important role in several fields (drug, dyes, semiconductors…) and in particular in pharmacology as drugs delivering systems
Menicacci, Eleonora. "Étude théorique de la décomposition thermique du nitrate d'ammonium en présence d'additifs et de contaminants". Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEC026.
Testo completoMany chemicals are likely to lead to incompatibility when they are brought into voluntary or accidental contact with other substances or materials. To control these chemical risks, particularly in the industrial environment, a rapid and precise identification of these incompatibilities is necessary. This identification is carried out so far by laboratory tests (DSC) and the results are collected, for example, in the safety data sheets of each product and in tables of incompatibility existing in the literature. However, the information provided is limited and does not make it possible to identify and understand the cause-effect relationship of the incompatibility between two substances concerned, nor the chemical mechanism by which this incompatibility occurs. In this context, a priori prediction of the reactivity between two molecules or more by molecular modeling becomes a complementary tool to the experimental tests in order to be able to reliably understand and predict the reaction paths and the products that form when chemical substances are in touch. A first thesis (S. Cagnina, 2011-2014), in collaboration with Chimie ParisTech, aims to improve the understanding of the mechanisms of chemical incompatibilities between chemical substances to increase the safety of substances during their use, storage and transport. Was interested in understanding at the molecular level some mechanisms of chemical incompatibilities involving ammonium nitrate (NA) using the tools of quantum chemistry, such as DFT. The proposed thesis aims to accumulate cases of incompatibility studies of contaminants with the NA to develop prediction methods (focusing on the key steps of the reaction mechanisms) of the presence or absence of incompatibility and thus go towards the Development of a prediction computer tool. Another scientific challenge is to associate with thermodynamic considerations, the kinetic dimension, to predict in particular the kinetics of formation of dangerous products. The results will be tested at INERIS or CERL (Canadian Explosive Research Laboratory)
Moreau, Christophe. "Des eaux souterraines salées en baie de Bourgneuf pour la production de microalgues en aquaculture : l'azote ammoniacal, le fer et le manganèse dissous, causes de la variabilité de la fertilité potentielle pour trois diatomées-tests". Nantes, 1996. http://www.theses.fr/1996NANT2039.
Testo completoMoussa, Mariam. "Loading of dendrimer nanoparticles into layer-by-layer assembled Poly(diallyl dimethyl ammonium) chloride-(Poly(acrylic acid))n Multilayer Films : Particle Electrokinetics, Film Structure Dynamics and Elasticity". Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0383/document.
Testo completoA detailed analysis of the physicochemical properties of engineered nanoparticles (NPs) is required to understand on a mechanistic level their interactions/potential toxicity with/towards biotic components of fresh water systems. Such an analysis is further mandatory to achieve a comprehensive evaluation and optimisation of the performance of (ultra)filtration methods developed to prevent NPs release into aquatic media. Within this context, the aim of this PhD thesis was to decipher the basic physico-chemical processes governing the loading of carboxylated-poly(amidoamine) (PAMAM-COOH) nanodendrimers -commonly employed in biomedical applications- into layer-by-layer assembled (poly(diallyl dimethyl ammonium) chloride-poly(acrylic acid))n ((PDADMAC-PAA)n) multilayer films. For that purpose, a systematic investigation of the electrohydrodynamic properties of PAMAM-COOH NPs was first performed as a function of pH and monovalent salt concentration in solution. On the basis of advanced electrokinetic theory for soft particles with zwitterionic functionality, it is demonstrated that the interfacial electrostatic features of the considered NPs are determined both by surface and bulk particle contributions to an extent that depends on electrolyte concentration. This leads to a remarkable NPs mobility reversal with changing monovalent salt concentration and to a marked dependence of the point of zero NPs mobility on electrolyte content. In addition, confrontation between experiments and theory further highlights how pH- and salt-mediated modifications of the NP particle structure affect dendrimer electrokinetic features at large pH and/or low salt concentrations. In a second part, the structure, morphology and mechanical properties of PDADMAC-PAA films, and their evolution over time under natural aging conditions or after thermal treatment, were addressed from atomic force microscopy (AFM) and Raman microspectroscopy analyses. Results evidence that PDADMAC-PAA multilayer films of exponential type exhibit mechanical and structural features that are typical for polyelectrolyte multilayer films with linear growth. In particular, their slow relaxation to equilibrium is accelerated after heating treatment at 60°C and, in line with density functional theory computation, this relaxation dynamics is shown to be intimately connected to instability of film domains rich in PDADMAC, depleted in water and marked by the presence of characteristic donut-like structures. In a final part, the reported dependence of PDADMAC-PAA multilayer films elasticity on concentration of nanodendrimers in bulk solution suggests that these complex multilayer films constitute a promising option to be further investigated for the loading and removal of carboxylated nanodendrimers from aqueous environments