Chimie

Nombre total de résultats : 150
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Investigation théorique des complexes d’inclusion acide acétylsalicylique:β-cyclodextrine via la méthode AIM et la dynamique moléculaire

BEZZINA Belgacem (2019)
Thèse de doctorat

La mécanique quantique et la dynamique moléculaire ont été utilisées pour étudier l'inclusion d'aspirine neutre et déprotonée dans la cavité de la β-cyclodextrine (β-CD). Tout d'abord, la mécanique quantique a été utilisée pour étudier les propriétés structurelles, énergétiques et topologiques du complexe neutre (ASA: β-CD) et de sa forme déprotonée (ASA–: β-CD). La nature et la force des interactions conventionnelles et non conventionnelles dans ces complexes ont été étudiées. Elle a été réalisée en combinant les critères théoriques d'Atoms In Molecules (AIM) suggérés par Koch et Popelier et la méthode des orbitales atomiques (NBO) à l'aide de la théorie de la fonctionnelle de la densité corrigée en dispersion (DFT-D3) avec la fonctionnelle B3LYP utilisant la base cc-pvdz dans la phase gazeuse.Tandis que la dynamique moléculaire a été utilisée pour étudier les processus d'inclusion des complexes (ASA:β-CD) et (ASA–:β-CD) pour déterminer l'énergie libre à l'aide de simulations non biaisées et biaisées. De plus, nous avons suivi la formation de liaisons hydrogène entre les molécules d’ASA/ASA– et la β-CD en fonction du temps d’un part, et la formation de liaisons hydrogène entre ASA/ASA– et les molécules d'eau, d'autre part. Voir les détails

Mots clés : Aspirine, Cyclodextrine, Mécanique quantique, Complexes d'inclusion, Simulation par dynamique moléculaire, Liaisons hydrogène.

Cr(VI) photocatalytic reduction under sunlight followed by Cr(III) extraction from TiO2 surface

Ridha Djellabi, Fouzi M.Ghorab, Sana Nouacer, Abdelaziz Smara, Ouahida Khireddine  (2016)
Publication

The main objective of this work was the extraction of Cr(III) from TiO2 surface deposited after Cr(VI) reduction by TiO2 solar photocatalysis. The results show that the reduction of Cr(VI) to Cr(III) by TiO2 under natural sunlight is total after 2 h using tartaric acid (A.T) as a hole scavenger under the following conditions: [Cr(VI)]: 20 ppm, [TiO2]: 2 g/L, [A.T]: 60 ppm and pH: 2.2. The produced Cr(III) is divided between deposited onto TiO2 surface (39.75%) and in the solution (60.25%). The Cr(III) removal from TiO2 surface by the sequential extraction after three washing were 90.13% and 42.62% using citric acid and EDTA respectively. Voir les détails

Mots clés : Chromium, Reduction, Deposition, Solar light, extraction, TiO2 surface

A Copper Oxide (CuO) Thin Films Deposited by Spray Pyrolysis Method

Y.BELLAL, A. Bouhank, H.Serrar, t.tüken, g.s???rc?k  (2019)
Publication

A simple and low-cost procedure (spray pyrolysis) was used to elaborate a copper oxide thin films on ordinary glass substrates. A copper nitrate was used and dissolved in two different solutions (Water, Methanol) S1 and S2 respectively in order to obtain an equal concentration; CS1,S2=0.5M. The spray pyrolysis deposition made at fixed temperature T=500°C and different volumes of S1 or S2 on the glass substrates. The X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis spectrophotometry were used to determinate the structural, morphological and optical properties of CuO thin films. The X-ray diffraction patterns confirm the presence of the polycrystalline phase of CuO as monoclinic crystal structure with preferential orientation along (110), (002), (111), (200) and (020). Their optical band gaps ranged from 3.95 to 4.02eV for thin films made with S1, and from 1.6 to 1.95eV for thin films made with S2 with a high absorbency in the visible region, which is in agreement with the values of the literature. Voir les détails

Mots clés : Copper oxide, Thin films, Spray pyrolysis, Band Gaps, XRD, SEM.

Study of thin Films of Nickel Oxide (NiO) Deposited bythe Spray Pyrolysis Method

Antar BOUHANK, Youcef. Bellal, Hacene Serrar  (2018)
Publication

Abstract: In this work, thin films of nickel oxide (NiO) were deposited by a simple and inexpensive technique, which is spraypyrolysis on ordinary glass substrates heated to a fixed temperature of 500 °C, from a solution containing nickel nitrate hexahydrateas a precursor dissolved in distilled water with deferent values of concentrations. The NiO thin films obtained were characterized todetermine the structure with X-ray diffraction technique (XRD), the absorption domain (UV-Visible Spectroscopy), and the surfacemorphology (SEM). The X-ray diffraction patterns confirm the presence of NiO phase with preferential orientation along the (111)direction. The optical gap for nickel oxide calculated with a concentration of 0.1 M from the measurement of optical absorption is 3.6eV, which is quite comparable to the value of the ratio. Voir les détails

Mots clés : NiO, Thin films, Spray pyrolysis

ETUDE DE LA PLASTIFICATION DU PVC PAR DES HUILES NATURELLES ALIMENTAIRES

BOUCHOUL Bousaha (2011)
Mémoire de magister

health starts several research to replace them by bio plasticizers, for that we studied the possibility of using the di ester isosorbide (DEI) and sunflower oil epoxydized as bio plasticizers. We manufactured PVC films containing various rates of DEHP, DEI and HTE. Then we carried out the analyses for the study of the mechanical (traction and hardness), thermals (coloring, TGA and DMA) and physic-chemical properties (volatility, extraction and leaching) according to change of the rate and the type of plasticizer. The results obtained show that the HTE has better thermal properties but very bad mechanical properties and physic-chemical, the DEI having almost the same properties or better than the DEHP. Voir les détails

Mots clés : PVC, DEHP, DEI, HTE, bio plasticizers, Volatility, extraction, leaching.

Quantitative and qualitative analyses of intermolecular interactions in neutral/deprotonated aspirin@β-CD inclusion complexes: QTAIM and NBO analyses

Belgacem BEZZINA, Rayenne Djemil, Nadjia Bensouilah  (2019)
Publication

Most of the researches in supramolecular chemistry area are focused on the conventional hydrogen bonds without taking into account unconventional intermolecular interactions. The nature and strength of the conventional and unconventional interactions in inclusion complexes formed between neutral aspirin (ASA) and its deprotonated form (ASA−) with β-cyclodextrin (β-CD) have been studied. It was conducted through combining atoms in molecules (AIM) theoretical criteria suggested by Koch and Popelier and natural bond orbital (NBO) analyses by means of dispersion-corrected density functional theory (DFT-D3) with the functional B3LYP using cc-pvdz basis set in the gas phase. We have found fve intermolecular closedshell interaction groups responsible for neutral ASA:β-CD and deprotonated ASA−:β-CD inclusion complexes stability: One is conventional O–H···O bond group. The four C–H···O, C–H···C, O–H···H–C and C–H···H–C groups are nonconventional. Also, with respect to the Koch and Popelier criteria, some of them present the properties of a hydrogen bond, while others do not. The non-covalent interaction energies are calculated using Espinosa approach. Finally, according to the AIM and NBO analyses, the topological parameters (electron density ρband its Laplacian ∇2ρb), estimated interaction energies (Eint), and the stabilization energy E(2)of both complexes were correlated with the intermolecular bond lengths Voir les détails

Mots clés : β-Cyclodextrin, Aspirin, Inclusion complex, DFT-D3, QTAIM, NBO

Poly Chlorure de Vinyle (PVC) Plastifié par des Mélanges des Plastifiants d’origineBiosourcés : Synthèse et Caractérisation

Boussaha BOUCHOUL, Mohamed Tahar BENANIBA  (2016)
Publication

L’huile de tournesol époxydée (HTE) avec un indice d’oxyrane de 4,5 a été synthétisée à partir de l’huile de tournesol vierge et l’eau oxygénée (H2O2) en présence de l’acide formique. L’HTE est utilisée avec le di esters isosorbide (DEI) comme un système plastifiant biosourcé dans le PVC en combinaison avec un plastifiant classique soit le di-éthyle-2-hexyle phthalates (DEHP).Après fabrication des films (0,5 mm d’épaisseurs) de différents pourcentages des plastifiants dans un mélangeur à deux cylindres, on a réalisé les essais de la migration et d’excudation des plastifiants des formulations obtenues. La migration des plastifiants biosourcés (DEI ou HTE) en combinaison avec le DEHP est suivie par les tests de volatilité, d’extraction et de lessivage. Les pertes des masses des formulations plastifiées réalisées obtenues par les différents modes de caractérisation à savoir: la volatilité, l’extraction dans l’eau distillée et dans la gazoline et le lessivage dépendent de la pression devapeur, de la masse moléculaire, de la solubilité, de la compatibilité et de la structure chimique du plastifiant. Voir les détails

Mots clés : PVC, Biosourcé, Epoxydation, plastifiants

Thermal and mechanical properties of bio-basedplasticizers mixtures on poly (vinyl chloride)

Boussaha BOUCHOUL, Mohamed Tahar BENANIBA, Valérie MASSARDIER  (2017)
Publication

The use of mixtures of nontoxic and biodegradable plasticizers coming from natural resources is a good way to replaceconventional phthalates plasticizers. In this study, two secondary plasticizers of epoxidized sunflower oil (ESO)and epoxidized sunflower oil methyl ester (ESOME) were synthesized and have been used with two commerciallyavailable biobased plasticizers; isosorbide diesters (ISB) and acetyl tributyl citrate (ATBC) in order to produce flexiblePVC. Different mixtures of these plasticizers have been introduced in PVC formulations. Thermal, mechanical andmorphological properties have been studied by using discoloration, thermogravimetric analysis (TGA), differentialscanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), tensile - strain and scanning electronmicroscopy (SEM). Studies have shown that PVC plasticization and stabilization were improved by addition ofplasticizers blends containing ISB, ATBC, ESO and ESOME. An increase in the content of ESO or ESOME improvedthermal and mechanical properties, whereas ESOME/ATBC formulations exhibited the best properties. Voir les détails

Mots clés : PVC, epoxidized sunflower oil, epoxidized sunflower oil methyl ester, isosorbide diesters, acetyl tributyl citrate.

ZnO nanoparticles and biocidal effect of nanostructured ZnO filmson Escherichia coli

Nabila Bouasla, Sihem Abderrahmane, Sameh Athmani, Amel Oulabbas, Mohamed Bououdina  (2018)
Publication

The biocidal effect of ZnO nanostructured films was studied using Escherichia coli ATCC 43897. TheZnO nanoparticles were synthesized in diethylene glycol by using zinc acetate forced hydrolysis.X-ray diffraction analysis confirmed the formation of single wurtzite-type ZnO phase with a crystallitesize of 20.59 nm. Transmission electron microscopy observations revealed spherical-shaped particlesin the nanoscale regime with a mean particle size of 21.96 nm. It was found that the addition oftrioctylphosphine during synthesis favored much improved dispersion of ZnO nanoparticles, withsmaller particle size; that is, 16.28 nm. Meanwhile, ZnO film grown onto glass substrate by spin-coatingrevealed single phase with the formation of aggregates (≈700) having mushroom-like morphologyformed of very fine particles in the nanoscale regime. The as-deposited nanostructured films exhibiteda hydrophilic character. The classical bacteriological and electrochemical impedance spectroscopymeasurements enabled the biocidal effect of ZnO nanostructured films with 94% inactivation efficiencyafter 90 min of contact time. Voir les détails

Mots clés : ZnO; Spin-coating; Nanostructured film; Biocide effect; E. coli; EIS

Effect of Biobased Plasticizers on Thermal, Mechanical, andPermanence Properties of Poly(vinyl chloride)

Boussaha BOUCHOUL, Mohamed Tahar BENANIBA, Valérie MASSARDIER  (2014)
Publication

Phthalates can be replaced by other harmless andenvironmentally friendly plasticizers, such as isosorbidediesters (ISB), and epoxidized sunflower oil (ESO),which has been proved an efficient stabilizer for poly(vinyl chloride) (PVC) in helping to prevent degradationduring processing. Formulations based on PVC withdifferent amounts of ISB, ESO, and di-(2-ethylhexyl)phthalate (DEHP) from 0 to 60 parts by weight per hundredparts of resin were realized. To make PVC flexiblewith partial amounts of the debated phthalates asplasticizers, we use a combination of DEHP, ISB, andESO. Effects of these two biobased plasticizers, ISBand ESO, and their mixture with DEHP on thermal stabilityby measuring discoloration degrees and thermalgravimetric analysis, on mechanical properties suchtensile strength, elongation at break, and hardness,were characterized. Plasticizer permanence propertiesof PVC compounds were studied. Studies showed thatprocessibility and flexibility were improved by the additionof a plasticizer system (ISB, ESO, and DEHP). Anincrease in the content of ISB and/or ESO increasedthermal and mechanical properties, whereas compositionswith ternary compositions of ISB/ESO/DEHP (15/15/30) exhibited the best performance properties. Voir les détails

Mots clés : PVC, Sunflower oil, Leaching, Volatility