Letteratura scientifica selezionata sul tema "Hydroxides Doubles Lamellaires"
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Tesi sul tema "Hydroxides Doubles Lamellaires"
Drici, Nawal. "Hydroxydes doubles lamellaires, synthèse, caractérisation et propriétés". Thesis, Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCD007/document.
Testo completoNew layered double hydroxides (LDHs) CoFe-Ac, CoNiFe-Ac, ZnNiFe-Ac and ZnCoFe-Acwith MII/MIII molar ratio of 3, and acetate ions in the interlayer region have been preparedusing forced hydrolysis of acetate metallic salts in a polyol medium. The structure,morphology and properties of as-prepared product were investigated by X-ray Diffraction(XRD), FT-IR Spectroscopy, elemental analysis, transmission Electron Microscopy (TEM),Scanning Electron Microscopy (SEM), thermal analysis (DTA, TGA) and V-visibleSpectroscopy: showed that these nanocomposites present the typical features of hydrotalcitelikestructure, exhibit a turbostratic character and the intercalation of acetate anions into theinterlayer domain has been successfully done, giving an interlayer spacing value of 12.70,12.47, 13.64 and 14.69 Å for CoFe-Ac, CoNiFe-Ac, ZnNiFe-Ac and ZnCoFe-Acrespectively.We can note that there is some difference between the interlayer spacing for all synthesizedphases. That can be explained by the arrangement of inserted species (anions + water) indifferent orientation in the interlayer domain.57Fe Mössbauer spectrometry allows concluding the presence of Fe3+ cations which occupyoctahedral sites and confirming the absence of Fe2+ in the as-prepared compounds.In order to check the capacity of our materials synthesized in polyol medium to exchange theacetate anions inserted in their interlamellar space, anionic exchange in aqueous medium waseffected for CoFe-Ac compound as à model of synthesized LDH. All the physicochemicalmethods of analysis (DRX, IR, ATD/ATG and elemental analysis) carried out on the materialCoFe- Ac /EC (exchanged). The comparison with a lamellar phase containing oFeCO3/Asynthesized in aqueous medium, show a layered double hydroxide compound with aturbostratic disorder, and a new interlamellar distance d003 = 7.67Å which correspondsperfectly with the presence of the carbonate anions and the water molecules in the interfeuilletfield.In the second part of this study, we are interested to examine the capacities of these kinds ofmaterials for the adsorption of an anion dye benzopurpurine-4B-. The adsorption of direct red2 by CoFe-Ac, CoNiFe-Ac LDHs has been examined in order to measure the capability ofthis new organic/inorganic nanomaterial to eliminate this highly toxic azoic class of anionicdyes from wastewater. The sorption capacities of LDHs for Benzopurpurine4B are also compared with those of other adsorbents : CoFe- Ac /Ec, CoFeCO3/A (synthesized in aqueous medium), Mg-Al-CO3/A and its calcined product at 500°C “Mg-Al-500”. The quantity of dye eliminated was found to depend on contact time, pH, initial concentration of dye and heating temperature. The thermodynamic parameters ΔG°, ΔH° and ΔS° werecalculated to predict the nature of adsorption. Results suggested that the Benzopurpurine 4B adsorption on different compounds was a spontaneous and endothermic process. Adsorption kinetic data were tested using pseudo-first order, pseudo-second order, Elovitch’sequation and intra-particle diffusion models. Kinetic studies for all cases showed that the adsorption followed a pseudo-second order reaction. Studies revealed that intra-particle diffusion played an important role in the mechanism of dye adsorption by MgAl-500. Theequilibrium data were analyzed using Langmuir, Freundlich, Tempkin, Elovitch, Dubinin-Radushkevich, Redlich-Peterson and Toth isotherm models. [...] Taking these results into account, we can conclude that prepared LDHs by forced hydrolysis in a polyol medium can be used successfully in the removal of anionic dyes from aqueous solutions
Touati, Souad. "Elaboration d'aérogels d'hydroxydes doubles lamellaires et de bionanocomposites à base d'alginate". Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2013. http://tel.archives-ouvertes.fr/tel-00975932.
Testo completoFaour, Azzam. "Relation entre synthèse, microstructure et propriétés électrochimiques d'hydroxydes doubles lamellaires (HDL)". Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2012. http://tel.archives-ouvertes.fr/tel-00822128.
Testo completoHallassi, Manel. "Elaboration, caractérisation et mesure d'activité catalytique et/ou photocatalytique sur des matériaux oxydes binaires et/ou ternaires". Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILR032.
Testo completoBimetallic (NiM (M=Cr, Fe), ZnM (M=Cr, Fe)) and trimetallic (NiZnM (M=Cr, Fe)) double lamellar oxide (DLO) catalysts with nominal compositions of Ni/M = 2 or 3 and Ni+Zn/Fe and Ni+Zn/Cr = 3, respectively, were prepared from the double lamellar hydroxides (DLH) using the co-precipitation method. The structure, texture and reducibility of the obtained catalysts were monitored by several physicochemical techniques: XRD, Raman, BET, XPS, TPR and SEM-EDX. The catalytic properties were evaluated for the dry reforming of methane reaction (CH4 + CO2 à 2H2 + 2CO). The structural study by XRD and Raman shows that the hydrotalcite structure was present at room temperature and stable up to 250 °C. The interspaces decreased as the temperature increased, with a lattice parameter and interspaces of 3.018 Å and 7.017 Å, respectively. The solids decompose completely into oxide after calcination at 500 °C. NiO, ZnO and spinel phases (NiM2O4 and ZnM2O4 M = Cr or Fe) were observed in NiM, Zn (M = Cr, Fe) and Cr2O3 were detected for chromium formulations. The NiFe and ZnFe catalysts show low activity in the DRM reaction over the entire temperature range studied. In contrast, the Cr-containing systems showed interesting CH4 and CO2 conversions and excellent H2 selectivity at low reaction temperatures. CH4 and CO2 conversions of 18-20% with H2/CO of about 0.7 at temperatures as low as 500°C, but transient behavior and deactivation were observed at higher temperatures or at long reaction times. The sequence was attributed to the stabilization of Ni metal particles formed during the reduction of the NiO phase due to the presence of NiCr2O4, paving the way for the use of these materials in periodic or looping processes for low temperature methane reforming
Di, Bitetto Arnaud. "Étude structurale et dynamique d’hydroxydes doubles lamellaires : du matériau carbonaté aux hybrides organo-minéraux". Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0191/document.
Testo completoThis thesis work is based on the synthesis and the characterization of layered double hydroxides (LDHs) by an approach combining vibrational spectroscopy, solid-state NMR and X-ray diffraction. The objectives include a description of the cations distribution in the layers, as well as a study of the structural and dynamic properties of the interlayer species. Investigations are mainly carried out for MgII/AlIII LDHs (ratio between 2 and 4) with an increased complexity of the intercalated species: from carbonate for which the materials have a preferential affinity, to other inorganic anions such as halides, perchlorate and nitrate, to finish with organo-mineral hybrids obtained by intercalation of organic anions/biomolecules (amino acids and cyclodextrins).The research carried out highlighted a local cationic order in the layers, preserved after anionic exchange. Furthermore, it has been possible to rationalize the behaviour of each anion in the interlayer space, which strongly depends on the layers charge density, as well as on the hydration state of the compounds. In particular, the coexistence between carbonate and hydrogenocarbonate anions in the interlayer space and their dynamic exchange with atmospheric carbon dioxide are revealed. On the other hand, a new interlayer dynamics probe by 27Al NMR is proposed. Finally, the step-by-step study of LDHs, first intercalating oxalate and then amino acids, allowed the transfer of the knowledge obtained for inorganic LDHs to organo-mineral hybrids. The manuscript ends with an application of cyclodextrins-containing hybrids for the treatment of water polluted with polycyclic organic compounds
Vialat, Pierre. "Composition, structure et comportement électrochimique d'Hydroxydes Doubles Lamellaires au cobalt : vers des applications en tant que matériaux d'électrodes". Thesis, Clermont-Ferrand 2, 2014. http://www.theses.fr/2014CLF22491/document.
Testo completoLayered Double Hydroxides (LDH) are lamellar materials with strong potentiality for numerous fields of application, however, their insulating electric character limits the possibilities for electrochemical applications. It is thus necessary to investigate for ways to improve their conductive properties. In this purpose, three approaches were envisaged: - insertion of cations of 3d transition metals into the lamellar sheets, - insertion of redox mediators between the layers or - addition of electronic percolants in the system to obtain “electroactive” LDH. Even if the possibilities of combination of divalent and trivalent metal cations within the LDH layer are tunable, all the studies were centered on the role of an element mainly, the cobalt. The chemical compositions of materials as well as their physico-chemical properties, in terms of morphology and global and local structure, were then studied by coupling various analytical techniques before realizing the characterization of the electrochemical properties by cyclic voltammetry and electrochemical impedance spectroscopy. These analyses then showed the application potentialities of certain type of LDH materials. The capacitive properties of CoIICoIII-CO3 phases were studied as supercapacitor electrode materials while the presence of a redox mediator as well as the immobilization properties for enzymes of the hybrid phase Co2Al-ABTS allowed constructing bioelectrodes potentially applicable in biofuel cell
Grosu, Elena-Florentina. "Layered double hydroxides and their composites : design, synthesis and specific applications". Thesis, Lille, 2019. http://www.theses.fr/2019LIL1R011.
Testo completoExploring the nano scale features of the matter and combining together different materials, novel composites with enhanced features can be fabricated, for their further utilization in biomedicine, catalysis, engineering, electronics, biotechnology and others. The anionic clays, also called layered double hydroxides (LDHs) are a category of hydrotalcite composites which possess high compositional variety, able to self-assembly. When used in presence of biological systems, they act as soft materials, with no significant effect over the constituent biomolecules. In this context, the thesis subject deals with the design of nanostructured composites LDHs type, for their further physicochemical characterization and utilization in photocatalysis, biomedicine and biochemistry. The first part of this work approaches the fabrication of self-assembled nanoparticles (NPs) as Au, In, Ag, and Ga on ZnLDHs materials by using co-precipitation, followed by reconstruction or impregnation synthesis methods. The applied characterization techniques proved that the novel materials have a hydrotalcite structure, they are crystalline and after reconstruction, the initial structure is recovered. The nanomaterials NPs/LDHs showed high photo-response activity when irradiated under simulated solar light and they were able to photodegrade organic pollutants as phenol, p-nitorphenol, acetophenone and diclofenac. The enhancement of hybrids performance, compared with their parent materials, is a consequence of the formation of surface separation between dispersed NPs and clay surface, which leads to recombination rate decrease. The second part of this thesis investigates the interactions between the LDHs or Au/LDHs based materials and Horseradish Peroxidase (HRP) enzyme. The results proved that the LDHs products resulted after clay calcination at 550 °C are capable to immobilize the enzyme via adsorption, with layered structure reformation. The kinetic data showed that only the materials without AuNPs retain the enzyme activity, while those with AuNPs in their structure are enzymatically inactive. The concept of photo-enzymatic degradation of phenol under solar irradiation and in presence of HRP/LDH biohybrid was also confirmed. The result was expressed as the synergetic effect between the enzymatic and the photocatalytic degradation. Furthermore, it was demonstrated that HRP can mediate the gold release from Au/LDH surface through HRP-AuNPs complex formation. In a separate study the nicotinamide adenine dinucleotide (NADH) cofactor was regenerated from NAD+ in presence of Au/LDH, solar light and using flavin mononucleotide (FMN) as an electron mediator. At a pH value of 8, the NADH regeneration was total in a time interval of two hours. In the last section of this work, the interactions between Au/LDHs materials and hepatitis B virus (HBV) were investigated. The cytotoxicity data have been demonstrated that the LDHs materials had no significant influence over cells viability. Remarkably, the Au/LDHs formulations have shown that they can inhibit the HBV proliferation. The parent LDHs materials manifest a modest antiviral activity
Grosu, Elena-Florentina. "Layered double hydroxides and their composites : design, synthesis and specific applications". Electronic Thesis or Diss., Université de Lille (2018-2021), 2019. http://www.theses.fr/2019LILUR011.
Testo completoExploring the nano scale features of the matter and combining together different materials, novel composites with enhanced features can be fabricated, for their further utilization in biomedicine, catalysis, engineering, electronics, biotechnology and others. The anionic clays, also called layered double hydroxides (LDHs) are a category of hydrotalcite composites which possess high compositional variety, able to self-assembly. When used in presence of biological systems, they act as soft materials, with no significant effect over the constituent biomolecules. In this context, the thesis subject deals with the design of nanostructured composites LDHs type, for their further physicochemical characterization and utilization in photocatalysis, biomedicine and biochemistry. The first part of this work approaches the fabrication of self-assembled nanoparticles (NPs) as Au, In, Ag, and Ga on ZnLDHs materials by using co-precipitation, followed by reconstruction or impregnation synthesis methods. The applied characterization techniques proved that the novel materials have a hydrotalcite structure, they are crystalline and after reconstruction, the initial structure is recovered. The nanomaterials NPs/LDHs showed high photo-response activity when irradiated under simulated solar light and they were able to photodegrade organic pollutants as phenol, p-nitorphenol, acetophenone and diclofenac. The enhancement of hybrids performance, compared with their parent materials, is a consequence of the formation of surface separation between dispersed NPs and clay surface, which leads to recombination rate decrease. The second part of this thesis investigates the interactions between the LDHs or Au/LDHs based materials and Horseradish Peroxidase (HRP) enzyme. The results proved that the LDHs products resulted after clay calcination at 550 °C are capable to immobilize the enzyme via adsorption, with layered structure reformation. The kinetic data showed that only the materials without AuNPs retain the enzyme activity, while those with AuNPs in their structure are enzymatically inactive. The concept of photo-enzymatic degradation of phenol under solar irradiation and in presence of HRP/LDH biohybrid was also confirmed. The result was expressed as the synergetic effect between the enzymatic and the photocatalytic degradation. Furthermore, it was demonstrated that HRP can mediate the gold release from Au/LDH surface through HRP-AuNPs complex formation. In a separate study the nicotinamide adenine dinucleotide (NADH) cofactor was regenerated from NAD+ in presence of Au/LDH, solar light and using flavin mononucleotide (FMN) as an electron mediator. At a pH value of 8, the NADH regeneration was total in a time interval of two hours. In the last section of this work, the interactions between Au/LDHs materials and hepatitis B virus (HBV) were investigated. The cytotoxicity data have been demonstrated that the LDHs materials had no significant influence over cells viability. Remarkably, the Au/LDHs formulations have shown that they can inhibit the HBV proliferation. The parent LDHs materials manifest a modest antiviral activity
Grégoire, Brian. "Relation Composition-Structure des Hydroxydes Doubles Lamellaires : Effets de la charge du feuillet et de la nature de l'anion interfoliaire". Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0154/document.
Testo completoThis manuscript is devoted to the comprehension of the relationship between the composition of Layered Double Hydroxides (LDH) and their structural properties. The first part of this manuscript is focalized on the formation and the structural properties of these materials. The influence of the cationic nature (MgII, NiII, CoII ; AlIII, FeIII) and their stoichiometries within the layer (MII/MIII E [2 ; 10]) constitutes the main axis of these investigations. The study of the hydrolytic behavior of a solution containing a mixture of divalent and trivalent cations as a function of their relative proportion allowed to propose a topotactic mechanism of formation of LDH phases. Moreover, it has been showed that the composition range is solely dependent on the nature of the cations. Thus, electrostatic models were designed to rationalize and predict the composition range as a function of the cationic nature. The second part is concerned with the properties of the interlayer domain. A joint study, coupling vibrational spectroscopies (Infrared and Raman) and X-ray diffraction allowed a detailed description of the influence of the cations and their stoichiometries on the organization of the interlayer anions (Cl-, CO32-, NO3-, ClO4-, aminoacids). The role of the interlayer water has also been investigated. Concerning hybrid organo-minerals, it has been showed that the layer charge dictates the orientation of the interlayered aminoacids, and consequently, their reactivity toward the formation of the peptide bonds. The enantioselective properties of the interlayer domain are highlighted toward the formation of peptides
Lainé, Maxime. "Etude du comportement de matériaux argileux sous rayonnement ionisant". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS192/document.
Testo completoThe aim of this PhD thesis is to study and understand, by proposing reaction mechanisms, the behavior under irradiation of various clay materials. The systems of interest were first synthetic talc, which is the prototype of a non-swelling material. Under irradiation by accelerated electrons, the production of dihydrogen in this system, due solely to surface hydroxyl groups, is of the same order of magnitude as the one obtained in liquid water. This yield is divided by 30 in the case of natural talc from Luzenac, thus highlighting the importance of the impurities as scavengers of the precursors of dihydrogen. Synthetic smectites, which are swelling materials, were then studied.The results evidence the radiolysis of water confined in the interlayer space, leading to H2 yields which may be two to three times higher than those measured in water. Moreover, they are similar for montmorillonite and saponite, evidencing that the charge location plays only a minor role. Finally, the study of double layered hydroxides or anionic clays shows that, in this case, the nature of the anion in the interlamellar space controls the reactivity. Parallel to these measurements, electron paramagnetic spectroscopy experiments have enabled proposing reaction mechanisms. Finally, all these results are of interest in the context of the disposal of radioactive waste
Libri sul tema "Hydroxides Doubles Lamellaires"
Berber, Mohamed Reda, e Inas Hazza Hafez. Recent Advances in Layered Double Hydroxide-Based Composites: Synthesis, Properties and Potential Applications. Nova Science Publishers, Incorporated, 2015.
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