Génie Chimique
Modélisation de la cinétique d’adsorption des HAP dans une colonne a lit fixe.
Par le passé, l’aspect essentiel des études hydrogéologiques consistait à estimer le potentiel d’alimentation en eau des aquifères. L’objectif est maintenant clairement axé sur les processus de transport et de dispersion, de retard et de dégradation des contaminants chimiques, les effets de l’hétérogénéité (du milieu) sur les trajectoires d’écoulement et les temps de parcours, et les phénomènes de rétention d’eaux contaminées dans les matériaux à faibles perméabilités. L’objectif de ce présent travail est de résoudre numériquement l’équation de transport de réactif à travers un milieu physiquement hétérogène dans le cas d’adsorption linéaire, et d’étudier l’influence de l’hétérogénéité physique sur la dispersion globale d’un polluant non-linéairement interactif.Nos résultats montrent l’importance déterminante de l’hétérogénéité physique du milieu poreux. En effet, Dans le cas d’une sorption non linéaire et dans un milieu poreux homogène, la cinétique affecte le comportement de soluté dans le milieu poreux, les fronts de concentration seront plus dispersifs et retardés par apport au cas d’une cinétique de sorption linéaire. Tandis que dans un milieu physiquement hétérogène, lorsque la sorption est linéaire, la dispersion du panache augmente fortement alors que l'hétérogénéité a un effet négligeable sur l'étalement du panache lorsque la sorption est non-linéaire. Voir les détails
Mots clés : modélisation, transport réactif, milieu poreux saturé, hétérogénéité physique.
Phenol photodegradation process assisted with Wells–Dawson heteropolyacids
This work aims to investigate the catalytic properties of the heteropolyacids (HPAs) withinphotocatalytic process. Photocatalytic degradation of phenol in aqueous solution was performedusing Wells–Dawson HPAs as catalysts under UV-illuminated condition at 254 nm.The effects of various parameters such as, concentration of catalyst, initial pH, and initialphenol concentration on the performance of photocatalytic process have been investigatedto obtain the efficient and durable catalysts and determine the better reaction conditions.The kinetics and the efficiency of phenol degradation were determined by various analyticaltechniques, such as HPLC and TOC. The results show that the photocatalytic degradationefficiency increases with decreasing pH and the optimum pH is 2 for both catalysts. Thephotodegradation follows pseudo-first-order kinetics with rate constants k = 8.56 × 10−2 and 9.94 × 10−2 min−1 for iron- and vanadium-substituted HPAs, respectively. Voir les détails
Mots clés : Well-Dawson HPA, Homogeneous catalysis, Phenol photodegradation, UV irradiation
Pillared clays as catalysts for methyl parathion removal by advanced oxidation processes
A natural bentonite from Mostaganem in Algeria was modified by intercalation with polyoxocationic solutions (Al•Fe, Al•Co, Al•Cu, Al•Fe•Cu or Al•Fe•La). The modification of the bentonite occurred via pillaring by ionic exchange with these solutions. The addition of these solutions led to the formation of pillared clays with important catalytic properties in environmental impact reactions. The structural and textural properties of materials calcined at 500 °C were determined by several techniques: X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and N2 adsorption–desorption analysis. The pillared clays were then used as a Fenton-type heterogeneous catalyst for the heterogeneous sono-Fenton process for the oxidation of methyl parathion in water. The catalytic tests revealed the activity of the introduced iron species and the promoter effect of lanthanide or copper on the catalytic activity of these species. The sono-Fenton method showed promising results for the degradation of methyl parathion when compared with the Fenton method. Therefore, the sono-Fenton method can be a viable alternative technology to the existing methods for treating methyl parathion in wastewater. Voir les détails
Mots clés : Advanced oxidation process, Pillared clay, Sono-Fenton, Methyl parathion pesticide, Wastewater treatment
Phenol photodegradation process assisted with Wells- Dawson heteropolyacids
This work aims to investigate the catalytic properties of the heteropolyacids (HPAs) within photocatlytic process. Photocatalytic degradation of phenol in aqueous solution was performed using Wells-Dawson HPAs as catalysts under UV-illuminated condition at 254 nm. The effects of various parameters such as, concentration of catalyst, initial pH and initial phenol concentration on the performance of photocatalytic process have been investigated to obtain the efficient and durable catalysts and determine the better reaction conditions. The kinetics and the efficiency of phenol degradation were determined by various analytical techniques, such as HPLC and TOC. The results show that the photocatalytic degradation efficiency increases with decreasing pH and the optimum pH is 2 for both catalysts. The photodegradation follows pseudo first-order kinetics with rate constants k = 8.56×10−2 min-1 and 9.94x10-2 min-1 for iron and vanadium substituted - HPAs, respectively. Voir les détails
Mots clés : Wells-Dawson HPA, Homogeneous catalysis, Phenol photodegradation, UV irradiation
Pillared clays as catalysts for methyl parathion removal by advanced oxidation processes
A natural bentonite from Mostaganem in Algeria was modified by intercalation with polyoxocationic solutions (Al•Fe, Al•Co, Al•Cu, Al•Fe•Cu or Al•Fe•La). The modification of the bentonite occurred via pillaring by ionic exchange with these solutions. The addition of these solutions led to the formation of pillared clays with important catalytic properties in environmental impact reactions. The structural and textural properties of materials calcined at 500 °C were determined by several techniques: X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and N2 adsorption–desorption analysis. The pillared clays were then used as a Fenton-type heterogeneous catalyst for the heterogeneous sono-Fenton process for the oxidation of methyl parathion in water. The catalytic tests revealed the activity of the introduced iron species and the promoter effect of lanthanide or copper on the catalytic activity of these species. The sono-Fenton method showed promising results for the degradation of methyl parathion when compared with the Fenton method. Therefore, the sono-Fenton method can be a viable alternative technology to the existing methods for treating methyl parathion in wastewater. Voir les détails
Mots clés : Advanced oxidatio process, Sono-Fenton, heterogeneous catalysis, Methyl parathion pesticide, Wastewater treatment
Adsorption d’un mélange binaire «plomb-nickel» par le kaolin
Le kaolin a été utilisé comme adsorbant pour éliminer le nickel et le plomb en mono adsorption et en mélange binaire. Le processus envisagé en régime statique et en mono adsorption a montré qu’un gramme de kaolin peut fixer 43,2 mg/g de nickel et 35,69 mg/g de plomb selon le modèle de Langmuir avec une cinétique de pseudo 1er ordre où le temps du pseudo équilibre est de 16 minutes pour Ni++ et de 14 minutes pour Pb++. Le rapport d’affinité RL a montré que le kaolin présente une bonne capacité d’adsorption. Pour le mélange binaire, l’expérience a montré que l’adsorption du nickel est la plus importante et le pseudo équilibre est plus lent que celui de l’ion seul. Toutefois, nous avons représenté approximativement le mélange avec le modèle de Langmuir généralisé et Langmuir généralisé modifié, en utilisant à la fois des données en mono constituant et en mélange. De ces deux représentations, nous avons constaté une inversion de sélectivité pour le modèle de Langmuir généralisé et une isotherme proche de celle de l’expérimentale pour le modèle de Langmuir généralisé et modifié. Voir les détails
Mots clés : Eau -dépollution- plomb- nickel- adsorption- kaolin
POLYPYRROLE COATED CELLULOSIC SUBSTRATE MODIFIED BY COPPER OXIDE AS ELECTRODE FOR NITRATE ELECTROREDUCTION
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
Effect of Welding Current on Microstructure Properties ofdissimilar metal joints
Dissimilar metal joints between X70 and duplex pipes will be required to prove their weldability in the oil and gas industry, the welds have been performed by GTA weldingprocess using alternating current, and different values of current (between 75 and 140A),without filler metal. The results show that, the heat input has a great influence on microstructure. The details of optical microscopic observations and Scanning electron microscopy (SEM) are discussed. Voir les détails
Mots clés : GTA welding, Dissimilar welding, welding current, HSLA, DSS, HAZ, microstructure
polypyrrole coated cellulosic substrate modified by copper oxide.
Firstly, the chemical polymerization of polpyrrole onto cellulosic substrate is conducted by using FeCl3 as an oxidant and pyrrole as monomer. Different parameters were tested (monomer concentration, duration of the experiment, nature of supporting electrolyte, temperature, etc…) in view to obtain films with different thickness and different morphologies. Thickness and topography of different PPy deposits (films) were estimated by a profilometer apparatus. The electrochemical reactivity of the obtained electrodes was tested by voltamperometry technique (CV) and electrochemical impedance spectroscopy (SIE).Secondly, the modification of the PPy film surface by incorporation of copper oxide nanoparticles is conducted by applying a galvanostatic procedure from a CuCl2 solution.Surface characterization has been carried out using scanning microscope (SEM) coupled with energy dispersive X-ray analysis (EDX), fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The analysis showed clearly the presence of the copper oxide nanoparticles (CuO and Cu2O) in the polymer films with dimensionsless than 50 nm. Voir les détails
Mots clés : modified polypyrrole, copper oxides
CuO grown on copper of high performance electrocatalyst for O2 electroreduction
The aim of this work is to synthesize copper oxide on copper electrode electrochemically for use in the O2 electroreduction. The growth of CuO arrays on Cu foil was demonstrated. The morphology and structure of the CuO were examined by X-ray diffraction spectroscopy. The catalytic performance of the obtained CuO/Cu electrode for O2 electroreduction was evaluated by means of cyclic voltammetry, chronoamperometry. Voir les détails
Mots clés : Copper substrate, electrocatalyst