Browsing by Author "Meguellati, Zineb"

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Catalytic Activity of Phenol Oxidation over Iron and Cooper-Exchanged Pillared Bentonite
(Springer Nature, 2024) Chellal, Khalida; Hamidouche, Fahim; Boudieb, Naima; Meguellati, Zineb; Trari, Mohamed
Al, mixed Al–Fe and Al–Cu pillared clays were prepared by the conventional method in a diluted medium with two additional parameters for the synthesis; the first one is the cooling of the clay suspension and the second is the exchange between the clay and metal solutions before pillaring with the polymeric mixed solution. The solids were characterized by X-ray diffraction (XRD), N2 adsorption and H2-TPR. The effects of the atomic ratio (M/Al + M) and hydrolysis molar ratio (OH/M), on the basal spacing and/or the specific surface were examined. The exchange does not seem to fix more Cu as in the case of Fe. The dispersion of the cold clay suspension, before pillaring, leads to a greater basal spacing of the solid at room temperature. In the case of mixed Al–Fe exchanged and/or pillared clays calcined at 350 °C, the cold dispersion of the clay suspension increases the basal spacing from 15.89 to 17.44 Å and from 15.32 to 16.07 Å for MR-AlFe (10) and Fe/MR-AlFe (10) respectively. Catalytic Wet Peroxide Oxidation (CWPO) of phenol under mild conditions (25 °C, 1 atm) was carried out without correction of pH. Mixed Al–Fe and Al–Cu pillared clays have comparable performances, although they showed some differences in the H2O2 decomposition kinetics. A total conversion of H2O2 is obtained without the complete phenol conversion over mixed Al–Fe pillared clays suggesting the presence of active species in these catalysts. In a slight excess of H2O2, the activity increases for all Fe-based clays catalysts with increasing the Fe content. A total conversion of phenol was obtained within 15 h of reaction over Fe/MR-AlFe (10) and after extending the reaction time to 30 h in the presence of Fe/MR-Al. On the contrary, MR-AlFe (10) only converted 57.12% under the same conditions. MR-AlFe (10) has the greater basal space (17.44 Å) and is more active for H2O2 decomposition than Fe/MR-Al, which certainly allowed greater accessibility of the reactant to the Fe-species. Fe exchanged and post-pillared clay with mixed (Al–Fe) solution containing 10% Fe expressed as molar percentage {Fe/MR-AlFe (10)} was the most efficient for this reaction combining good catalytic activity with high stability against iron leaching (0.02%). It showed a total phenol degradation, the highest H2O2 decomposition (85.7%) and more than 80% of TOC removal after 15 h of reaction.
Flower‑Like Layered Double Hydroxides for the Adsorption of Azocarmine G: Kinetic, Isotherm, and Thermodynamic Studies
(Springer, 2023) Meguellati, Zineb; Ghemmi, Naima; Brahimi, Razika
The current research includes the adsorp- tion behavior of two flower-like layered double hydroxides (MgAl-LDH and MgFe-LDH) synthe- sized via co-precipitation method for the environ- mental remediation. The synthesized materials were characterized by several techniques like X-ray diffrac- tion (XRD), Fourier Transform Infrared spectrom- etry (FTIR), scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), differential ther- mogravimetry (DTG), and differential scanning calo- rimetry (DSC). The materials were also characterized by Brunauer-Emmett-Teller (BET) technique, and the obtained surface areas were 65.50 m2 ·g−1 and 51.43 m2 ·g−1 for MgAl-LDH and MgFe-LDH, respectively. The materials were tested for the adsorption removal of azocarmine G dye from aqueous medium; the experimental parameters, including the pH, the initial concentration, the adsorbent dose, and the time, were optimized to attain a maximum adsorption capacity of 105.9 mg·g−1 and 101.6 mg·g−1 for MgAl-LDH and MgFe-LDH, respectively, which confirms that the materials can be used for the effective dye removal. The kinetic study revealed that the pseudo-second order fitted well the adsorption process, and the iso- therms conformed well to the Langmuir model. The effect of temperature allowed to calculate the follow- ing thermodynamic parameters: ΔHMgAl°=12.083 KJ·mol−1 ; ΔHMgFe°=25.053 KJ·mol−1 ; ΔSMgAl°=43.81 JK−1 ·mol−1 ; and ΔSMgFe°=87.75 JK−1 ·mol−1 .
Insight into the adsorption of acid fuchsin using CoAl layered double hydroxide: Central composite design, kinetics, isotherms and thermodynamic studies
(Elsevier, 2023) Meguellati, Zineb; Ghemmit-Doulache, Naima; Brahimi, Razika
Massive amounts of wastewater contaminated by hazardous and synthetic dyes are produced by the textile industry. Therefore, it is crucial to develop innovative techniques for removing these pollutants. In the present study, CoAl- LDH with excellent adsorption ability was synthesized via coprecipitation method at ambient temperature. The surface morphology and composition of the resulted compound were evaluated using several methods including X-ray diffraction (XRD), Fourier Transform Infrared spectrometry (FTIR), scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), differential thermogravimetry (DTG), and Differential scanning calorimetry (DSC). The results given by Brunauer, Emmett and Teller theory (BET) showed that the material has a specific surface area of 48 m2.g−1 and pore volume of 0.42 cm3.g−1. The as-synthesized material was tested for the acid fuchsin removal from an aqueous medium and the impact of several parameters was investigated. The experimental parameters such as the pH, the initial concentration, the adsorbent dose and the time were optimized using the central composite response surface methodology. The optimal adsorption capacity is attained at pH = 4.5, Initial concentration C0 = 96.71 ppm, adsorbent dose d = 0.40 g.L−1 and time t = 180 min. The adsorption process fitted well with the pseudo-second order reaction, and followed Langmuir adsorption isotherm providing a considerable Langmuir adsorption capacity of 384.6 mg. g−1. The effect of different temperatures reveals the thermodynamic parameters, i.e., the free Gibbs energy ΔG° (−4.86 to −1.16 kJ.mol−1), enthalpy change (ΔH° = 79.69 kJ.mol−1) and entropy (ΔS° = 137.61 JK−1.mol−1), the negative ΔG° and positive ΔH° values signify that the fuchsin acid adsorption is spontaneous and endothermic.
Synthèse électrochimique de films d'hydroxydes doubles lamellaires sur un substrat métallique : application à l'environnement
(Université M'Hamed Bougara Boumerdès : Faculté des Sciences, 2023) Meguellati, Zineb; Ghemmit-Doulache, Naïma(Directeur de thése)
L'augmentation de la consommation de produits chimiques a considérablement amplifié la contamination organique des effluents aquatiques et des ressources des eaux. L'objectif de ce travail est l'élaboration des hydroxydes double lamellaires (HDL) suivant deux méthodes, et leur application dans le domaine environnemental. Plusieurs techniques physicochimiques, notamment XRD, FTIR, SEM/EDS, TGA/DTG et caractérisations électrochimiques, ont été utilisées afin d'évaluer les propriétés structurelles et morphologiques des poudres de MgAl-HDL, MgFe-HDL et CoAl-HDL synthétisées par la méthode de coprécipitation. D'autre part, des films minces de MgAl-HDL et de CoAl-HDL ont été électrodéposés avec succès sur des substrats métalliques (électrodes de Nickel et d'acier inoxydable). Des poudres MgAl-HDL, MgFe-HDL et CoAl-HDL ont été appliquées pour l'adsorption de l'azocarmine G (ACG), et les paramètres expérimentaux ont été optimisés à l'aide de la méthode des surfaces de réponse pour atteindre des capacités d'adsorption (mg/g) expérimentales maximales de 105,9 ; 101,6 et 98,66 pour MgAl-HDL, MgFe-HDL et CoAl-HDL, respectivement. Le comportement d'adsorption du MgAl-HDL électrodéposé sur une électrode en acier inoxydable a été testé en vue de l'élimination du bleu de bromophénol (BPB), l'effet des conditions expérimentales a été étudié et la capacité d'adsorption maximale était de 4,96 mg/g. Plusieurs modèles cinétiques et isothermes ont été appliqués aux résultats expérimentaux pour évaluer les processus d'adsorption. L'aspect énergétique des processus a été également étudié en déterminant les paramètres thermodynamiques tels que l'énergie libre standard de Gibbs (?G?), l'enthalpie (?H?) et l'entropie (?S?). La régénération des matériaux a été étudiée par deux voies chimiques et électrochimiques ; les expériences ont révélé que l'utilisation de poudres a permis d'obtenir des capacités d'adsorption extrêmement élevées, tandis que l'avantage de l'utilisation de film formé réside dans la rapidité, la simplicité et l'efficacité de la régénération. La poudre de MgFe-HDL synthétisée via la méthode de coprécipitation a été utilisée pour la modification de l'électrode en graphite (électrode G/MF). L'électrode modifiée a été ensuite testée pour la détection électrochimique sélective du métronidazole (MNZ) par voltamétrie cyclique. Le capteur développé a présenté de bonnes performances en termes de sensibilité et de sélectivité avec une limite de détection de 0,74 mM