Génie Chimique

Nombre total de résultats : 45
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Développement d'électrodes modifiées à base de films minces électroactifs. Application à la détection électrocatalytique

Cherif DEHCHAR (2017)
Thèse de doctorat

Au travers de ce projet de thèse, nous nous sommes fixés pour objectif la mise au point de nouveaux matériaux fonctionnels appliqués en électroanalyse. Il s'agit de développer de nouvelles électrodes modifiées ayant de grandes performances analytiques par dépôt de films minces métalliques à base d'argent ou de cuivre sur un substrat non-conducteur de verre époxy ; ou encore, par une dispersion de microparticules d'un métal noble à propriétés catalytiques, tel que le palladium, sur la surface d'un film polymère conducteur, tel que le polypyrrole électrogénéré sur silicium. Pour ce faire, nous avons opté pour la technique de dépôt par bain chimique afin de réaliser les dépôts métalliques d'argent et de cuivre ; et pour les méthodes électrochimiques de déposition, à savoir l'électropolymérisation et l'électrodéposition pour synthétiser les films composites palladium-polypyrrole. L'étude de la réactivité électrochimique des électrodes élaborées a pour objectif d'envisager leur utilisation comme capteurs voltammétriques dédiés à la détection de différentes substances d'intérêt pharmaceutique ou biomédical, telles que le peroxyde d'hydrogène, le formaldéhyde et l'acide ascorbique. La démarche que nous avons entreprise afin d'améliorer les caractéristiques analytiques de nos électrodes consiste à mettre en synergie les propriétés physicochimiques des dépôts et la réactivité électrochimique des électrodes élaborées en étudiant l'effet des paramètres de synthèse les plus influents de sorte à maîtriser leur influences sur les performances électrocatalytiques des électrodes, ainsi pour assurer une bonne reproductibilité des mesures. Voir les détails

Mots clés : Argent, capteur, Electrode modifiée, couches minces, composites, Polypyrrole

Computation Of The Energy Density Of The Adsorption Sites By Inverse Gas Chromatography

BOUHANK Antar, BENCHEIKH Lahcene (2017)
Article de conférence

Inverse Gas Chromatography (I.G.C) technique can be used to determine the adsorption properties of the stationary phase of various materials. The problem is formulated in terms of an integral equation where the unknown is the energy density. The integral equation is a Fredholm integral equation of the first kind. Generally, integral equations cannot be solved analytically. Resort is often made to numerical methods of solutions. The kernel of the integral equation is the adsorption model. For some special models, a solution in a closed form was obtained. Some results are presented.Voir les détails

Mots clés : Inverse gas chromatography, adsorption energy, adsorption models, integral equation

Réactivité électrochimique des électrodes composites (polymères conducteurs, catalyseurs) appliquées à l’électrocatalyse et à la dépollution.

Abderrazak HAMAM (En préparation)
Thèse de doctorat

The aim of this work is to synthesize polypyrrole (PPy) films on nonconducting cellulosic substrateand modified by copper oxide particles for use in the nitrate electroreduction process. Firstly, thechemical polymerization of polypyrrole onto cellulosic substrate is conducted by using FeCl3 as anoxidant and pyrrole as monomer. The thickness and topography of the difierent PPy films obtainedwere estimated using a profilometer apparatus. The electrochemical reactivity of the obtainedelectrodes was tested by voltamperometry technique and electrochemical impedance spectroscopy.Secondly, the modification of the PPy film surface by incorporation of copper oxide particles isconducted by applying a galvanostatic procedure from a CuCl2 solution. The SEM, EDX and XRD analysis showed the presence of CuO particles in the polymer films with dimensions less than 50 nm.From cyclic voltamperometry experiments, the composite activity for the nitrate electroreductionreaction was evaluated and the peak of nitrate reduction is found to vary linearly with initial nitrateconcentration. Voir les détails

Mots clés : Polypyrrole, cellulosic, CuO, electrocatalysis, Nitrate

ETUDE DES PROPRIETES PHYSICO-CHIMIQUES DES OXYDES DE TITANE OBTENUS PAR VOIE SOL-GEL

Abderrazak HAMAM (2012)
Mémoire de magister

In this work, simple and composite xerogels based alcoxydes of titanium and silicon to knowing the titanium tetraisopropoxide Ti[OCH(CH3)2]4 , tetramethoxysilane Si(CH3)4 : were prepared by sol-gel processing. The solutions were prepared in acid, basic and neutral mediums. The gelation of these solutions whereas it varies between 5 hours and 9 days for the simple xerogels whiles it varies between 3-9 days for the composite xerogels. The gel obtained was dried at ambient temperature. The microstructural evolution of the simple and composite xerogels was followed by the differential thermal analysis (DTA), thermogravimetrie (TG) and by Fourier transforms infrared spectroscopy (FTIR). Voir les détails

Mots clés : : Sol-Gel, Xerogels, titanium, composite, thermal analysis, FTIR

POLYPYRROLE COATED CELLULOSIC SUBSTRATE MODIFIED BY COPPER OXIDE AS ELECTRODE FOR NITRATE ELECTROREDUCTION

A. HAMAM, D. Oukil, A.Dib, H. HAMMACHE, L. MAKHLOUFI, B. SAIDANI (2015)
Article de journal

The aim of this work is to synthesize polypyrrole (PPy) films on nonconducting cellulosic substrate and modified by copper oxide particles for use in the nitrate electroreduction process. Firstly, the chemical polymerization of polypyrrole onto cellulosic substrate is conducted by using FeCl3 as an oxidant and pyrrole as monomer. The thickness and topography of the diferent PPy films obtained were estimated using a profilometer apparatus. The electrochemical reactivity of the obtained electrodes was tested by voltamperometry technique and electrochemical impedance spectroscopy. Secondly, the modification of the PPy film surface by incorporation of copper oxide particles is conducted by applying a galvanostatic procedure from a CuCl2 solution. The SEM, EDX and XRD analysis showed the presence of CuO particles in the polymer films with dimensions less than 50 nm. From cyclic voltamperometry experiments, the composite activity for the nitrate electroreduction reaction was evaluated and the peak of nitrate reduction is found to vary linearly with initial nitrate concentration.Voir les détails

Mots clés : Polypyrrole, cellulosic, CuO, electrocatalysis, Nitrate

Polypyrrole coated paper substrate decorated with silver nanoparticles

A. HAMAM, D. Oukil, M. Maiza, L. MAKHLOUFI, M. M. Chehimi (2017)
Article de conférence

The main objective of the present study is to elaborate a new electrode material based on polypyrrole deposited on an inert paper substrate and decorated with silver nanoparticles. So we report the chemical polymerization of polypyrrole on paper substrate by the use of iron (III) chloride (FeCl3) as oxidant. The silver polypyrrole (Ag/PPy) composite is prepared by simple chemical reduction process from an AgNO3 solution on previously chemically synthesized PPy thin films onto the cellulosic sheet. The electrochemical reactivity of the obtained electrodes was studied by voltamperometry technique and electrochemical impedance spectroscopy (EIS).Additionally, the electrode materials were characterized via FTR, XPS, XRD, SEM and EDX.Voir les détails

Mots clés : Paper substrate, Polypyrrole, chemical synthesis, Silver

Purification and detoxification of petroleumrefinery wastewater by electrochemical process

N. Gousmi, A. Sahmi, H.Z. Li, S. Poncin, R. Djebbar & K. Bensadok (2016)
Article de journal

The treatment of synthetic oily wastewater having the characteristics of a typical petrochemicalwastewater (PRW) by electrocoagulation (EC) using iron and aluminum electrodes was conducted inan electrolytic reactor equipped with fluid recirculation. During the treatment, the emulsion stabilitywas followed by the measurement of Zeta potential and particle sizes. Effects of some operatingconditions such as electrodes material, current density and electrolysis time on removal efficiencies ofturbidity and chemical oxygen demand (COD) were investigated in details. The PRW purification byEC process was found most effective using aluminum as anode and cathode, current density of 60A/m2 and 30 min of electrolysis time. Under these conditions, the process efficiencies were 83.52%and 99.94% respectively for COD and turbidity removals which correspond to final values of 96 mgO2/L and 0.5 NTU. A moderate energy consumption (0.341 kWh) was needed to treat 1 m3 of PRW.Besides, the ecotoxicicity test proved that toxic substances presented in the PRW, and those inhibitingthe germination growth of whet, were eliminated by the EC technique.Voir les détails

Mots clés : petroleum wastewater purification, electrocoagulation, energy consumption, ecotoxicity test.

Etude de quelques modèles pour le calcul des densités énergétiques des sites d'adsorption en utilisant la chromatographie gazeuse inverse

BOUHANK Antar, BENCHEIKH Lahcene (2017)
Article de conférence

L'application de la chromatographie gazeuse inverse (CGI) pour la détermination des grandeurs physico-chimique qui caractérisent l'interaction entre une molécule sonde et un support chromatographique est déjà ancienne puisque les premiers travaux remontent aux années quarante. les nombreuses possibilités offerts par cette méthode sont décrites dans plusieurs ouvrages. on se propose dans ce sujet d'explorer quelques modèles d'adsorption pour caractériser la densité énergétique des sites d'adsorption pour ce faire on s'appuie sur de nombreux travaux déjà effectués .L'objet recherché est de contribuer à la recherche de nouveaux moyens pour caractériser l'hétérogénéité de la surface des solides.Voir les détails

Mots clés : chromatographie gazeuse inverse, modèles d'adsorption, densité énergétique, surface hétérogène

TWO-STEP ELECTROLESS SYNTHESIS OF A COPPER/SILVERCOMPOSITE FILM FOR ELECTROCATALYTIC OXIDATION OF FORMALDEHYDE

Charif DEHCHAR, Rochdi KHERRAT (2016)
Article de conférence

In this work, we report a two-step electroless plating process for preparing a copper/silver composite film on a Resin Epoxy (RE) substrate. First, silver film was deposited on RE substrate from a silvering bath. Then, copper was deposited on silver film at 95 °C from a separate solution containing copper ions and formaldehyde as reducing agent. The electrochemical reactivity of the prepared copper/silver composites was investigated towards the electrochemical oxidation of formaldehyde. Scanning electron microscopy of the composites showed a porous microstructure with uniform surface morphology. The presence of silver and copper onto the RE surface was confirmed by energy dispersive X-ray analysis. The formaldehyde oxidation peak on the copper/silver electrode is obtained at -0.3 V/SCE. The electrode showed a significant electrocatalytic activity with good repeatability and stable electrochemical response.Voir les détails

Mots clés : copper, Electroless deposition, Formaldehyde, Silver, thin film

Elaboration of Natural Hydroxyapatite Using Calcination at Various Temperatures

A. Azzi, L. Bahloul, L. Alimi, H. REZZAG, S. Guerfi, M. Mokhtari (2016)
Article de conférence

The use of hydroxyapatite HA as fillers, spacers, and bone graft substitutes have received considerable attention, primarily because of their biocompatibility, bioactivity and osteoconduction as regards the characteristics to host tissues.We developed hydroxyapatite subjected at different calcination temperature (900, 1200 °C) for ninety minutes with respect to their chemical and structural properties. Simultaneous thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) was performed for our powder using a Q600 SDT equipment, 20 mg of this powder was heated in an alumina crucible at a rate of 10 ° C / min.Voir les détails

Mots clés : Calcinations, hydroxyapatite, Chemical and structural properties