Thèses doctorat

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ANALYSE ET MODELISATION DES EXTREMES DE TEMPERATURE AU NIVEAU DE QUELQUES STATIONS TYPES DU NORD OUEST ALGERIEN
(University of sciences and technology on Oran, 2015-03-03) ABDERRAHMANI, BELAID; M. HAOUARI; A. DOBBI; M. HADJEL; N. HASSINI
Le caractère permanent de la température lui confère un rôle déterminant en bioclimatologie. Ses valeurs minimale et maximale revêtent un intérêt particulier du fait qu'elles soient quelques fois liées à une situation météorologique "à risque", pouvant générer des phénomènes exceptionnels souvent dommageables tels les vagues de chaleur ou de froid. Ainsi, la canicule de l’été 2003 en France s’est soldée par un nombre important de décès parmi les personnes vulnérables tels que les malades ou les personnes âgées. En décembre 2004, une vague de froid, accompagnée de fortes gelées a causé d’importants dommages aux cultures maraîchères dans la région de Ain Defla (Algérie). D’où l’intérêt porté dans cet article à l’analyse des extrêmes de température en Algérie. Ceci permet d’apprécier le risque d’occurrence de tels événements extrêmes et par suite d’en limiter les impacts souvent sévères sur des secteurs sensibles tels que l’agriculture, les ressources en eau ou la santé.
Caractérisation de la vase de dragage du barrage de l’Oued Fodda et valorisation en tant que matériau de construction
(University of sciences and technology in Oran, 2015-10-25) Benasla, Mohamed
La retenue du barrage de l’Oued Fodda est soumise à une forte Sédimentation en raison des volumes considérables d'apports solides transportés chaque année par les rivières surtout lors des fortes crues. C’est ainsi, qu’un volume de 103.10 6 m 3 de vase s’est déposé réduisant ainsi sa capacité à moins de 45 % [1]. Afin de prolonger la «durée de vie» de cet ouvrage, le dragage de la retenue est devenu une solution indispensable malgré les énormes quantités de vases extraites par les vannes de fond du barrage et qui ne trouvent aucune application et leur stockage pose actuellement un problème qui menace l'environnement. Dans cet article, nous allons faire une étude basée sur des analyses physiques, chimiques et minéralogiques de la vase prélevée dans la retenue du barrage de l’Oued Fodda. Les résultats des analyses obtenus vérifient bien les normes d’une argile utilisée pour la fabrication de céramique.
Desalination and Water Treatment
(University of sciences and technology in Oran, 2015-05-25) Azri Yamina, Mounia; Zerouali, Djilali
In this study, the electrochemical deposition of gold (Au) onto graphite has been performed under different deposition potential conditions. These Au particles electrodeposited on the graphite were used as cathode for O2 electrochemical reduction and H production in acidic solution, and the hydrogen peroxide (H2O) electrogenerated on graphite modiﬁed by gold particles was used in electro-Fenton process. Results show ﬁrstly that the O2 cathodic reduction on gold particles electrodeposited on the graphite electrode in acidic medium with two well-deﬁned reduction waves at −300 mV/SCE and −1,300 mV/SCE; those waves indicated reduction of two O2 electrons to H2O. Secondly, the optimal cathodic potential condition for H2O 22 generation on cathode modiﬁed was −300 mV and unmodiﬁed one was −500 mV/SCE. The electrolysis time, dissolved oxygen level, magnetic stirring, and pH were systematically studied; the hydrogen peroxide production increased with the aeration and electrolysis time and then became stationary after 2 h of electrolysis. The maximum Haccumulation increased up to 60 mg/L with air compressed, at −300 mV. Optimized parameters (potential, oxygen level, and concentration of ferrous ions) were also applied to incinerate the Belgard EV2030 sodium salt of polycarboxylic acid. The incineration efﬁciency onto optimized parameters shows that 74% of Chemical oxygen demand was incinerated in the modiﬁed electrode that conﬁrms the positive gold modiﬁcation effect onto the performance.
Influence of Hydration on the Neutral Complex ( - OH, H 3 O + ) (H 2 O) n
(University of sciences and technology in Oran, 2015-05-19) Benyettou, Fatma; S.HIADSI; A.BENDRAOUA
Density-functional theory (DFT) within local density approximation (LDA) has been carried out for a sequence of hydrated proton clusters. Optimised structures were odtained for n=0, 1 and OH, H3O+)(H2O)n, complex . Hydronium ion H3O+ and hydroxide ion OH are found to be the center of the neutral complex (-OH, H3O+-). The LDA give shorter hydrogen bond lengths O-H, bslightly longer chemical bond lengths O…H as compared with the Post-Hartree-Fock calculations.We found that the distance O...H successively increases with the number of water molecules added to the neutral complex (-OH, H3O). The solvent effects on proton transfer energy barriers in clusters have been studied. The harmonic vibrational frequencies and IR intensities of various modes have been generated for all optimised structures. This study was confirmed by vibrational studies of these complexes, our results give excellent agreement with experimental values.
Lignosulfonate interleaved layered double hydroxide: A novel green organoclay for bio-related polymer
(University of sciences and technology in Oran, 2014-04-19) Hennous, Mohammed; Derriche, Zoubir; Privas, Edwige; Navard, Patrick; Verney, Vincent; Leroux, Fabrice
New organic inorganic layered double hydroxide (LDH) organoclays are assembled through coprecipitation with lignosulfonate (LS) interleaved inorganic host structure sheets. The biopolymer is found to accommodate the interlayer space adopting a bilayer molecular arrangement resulting in a basal spacing of 2.54 nm. However the crystallinity of the resulting bio-organoclay is weak, probably due to the difﬁculty of the inorganic sheets to be built on amorphous polymer chain, the latter inducing low structural ordering. An organoclay of composition Zn Al/LS is subsequently used as ﬁller in three bio-related polyesters, poly(lactic) acid (PLA), poly(butylene) succinate (PBS) and poly(butylene adipate-co-terephthalate) (PBAT). Melt polymer extrusion using 5 wt.% organoclay loading yields polyester nanocomposite with a nanocomposite structure largely intercalated for both PLA and PBS (Δd (expansion)>6 nm) while a non miscible structure is obtained for PBAT. The incorporation of hydrophilic Zn 2Al/LS platelets decreases the water/polymer contact angle of about 10° for the LDH/LS PBAT composite only. A strong increase of the complex viscosity |η*| is observed for both nanocomposites Zn22Al/LS PLA and PBS compared to the polyester itself. This is explained on the basis of a chain extender behavior of the intercalated Zn Al/LS platelets towards polymer chains as evidenced on the Cole Cole representation showing an increase of the real viscosity in the low-ω region. In opposition a strong decrease in |η*| is observed for PBAT, underlining a plasticizing effect of the organoclay ﬁller. Comparatively, the thermal stability of PLA is slightly enhanced with an increase of T2 value while PBS and PBAT bio-nanocomposites degrade at slightly lower temperature.
Reduction of the Additives Migration from Poly Vinyl Chloride Films by the Use of Permanent Plasticizers
(University of sciences and technology in Oran, 2015-05-07) M. O. Boussoum; N. Belhaneche-Bensemra
This aim of this work is to study the partial replacement of the plasticizer ordinarily used di-octyl phtalate (DOP) by the permanent plasticizers ethylene-vinyl-acetate (EVA) and acrylonytrile-bu- tadiene-styrene (ABS) in order to reduce migration of additives initially contents in polyvinyl chloride (PVC) stabilized with expoxidized sunflower oil (ESO). Migration tests with agitation to 40˚C in sunflower oil and ethanol at 15% were made. Migration phenomenon was studied on the basis of the PVC samples mass variations, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) analysis. The results showed the effectiveness of the approach consisting in the partial substitution of DOP by plasticizers of polymeric nature. The fol-lowing order concerning the migration of additives was found: DOP (40) > DOP:EVA > (30/10) DOP: ABS (30/10). Furthermore, all the measured values of overall migrations were lower than the maximum allowable overall migration: 10 mg∙dm^2.
Removal of Furfural from Aqueous Solutions by Adsorption Using Organobentonite: Isotherm and Kinetic Studies
(2015-05-03) Mebrek, Ouassila Rachedi; Derriche, Zoubir
Lubricant refineries are facing pollution problems associated with the occasional loss of furfural. This constitutes both an economic loss and an environmental hazard, especially for aquatic organisms. Some studies on the removal of furfural by adsorption onto hydrophobic polymeric resins (XAD-4 and XAD-7), activated carbon and the nanoporous material MCM-48 have been published, but none provides information on the adsorption of furfural onto clays. In the present work, we have studied the efficiency of sodium bentonite modified with the cationic surfactant cethyltrimethylammonium bromide (CTAB) in the adsorption of furfural. The structures of both natural and modified bentonites have been examined using XRD and FT-IR analyses. Adsorption studies were performed in a batch system, with the effects of various experimental parameters such as the contact time, the organobentonite concentration, pH, the initial furfural concentration and the temperature being evaluated. Kinetic results showed that furfural could be removed by CTAB–bentonite after contact for 6 h, with the adsorption process being well described by the pseudo-second-order reaction model. Furfural sorption onto CTAB–bentonite was characterized by a linear isotherm, with the adsorption capacity towards furfural being reduced by increasing temperature. A comparison of furfural adsorption capacities revealed that the capacities decreased in the following order: CTAB–bentonite > XAD-4 > XAD-7.
Removal of Orange II by Phosphonium-modiﬁed Algerian Bentonites
(University of sciences and technology in Oran, 2015-04-28) Bouzid, Samia
An Algerian montmorillonite was modiﬁed with two organic surfactants, methyltriphenyl phosphonium bromide and n-hexyltriphenyl phosphonium bromide. The solids obtained were used as adsorbents to remove Orange II, an anionic dye from aqueous solutions. Batch experiments were conducted to study the effects of temperature (20–60 C), initial concentration of adsorbate (50–150 mg L_1 ) and pH of solution 6.5 on dye adsorption. Due to their organophilic nature, exchanged montmorillonites were able to adsorb Orange II at a very high level. Adsorption of Orange II for B-NHTPB and B-MTPB at different pH show that the adsorption capacity clearly decreases with an increase in pH of the initial solution from 2 to 8, this decrease being dramatic for pH>8. This may be due to hydrophobic interactions of the organic dye with both phosphonium molecules and the remaining non-covered portion of siloxane surface. The kinetics of the adsorption was discussed on the basis of three kinetic models, i.e., the pseudo-ﬁrst-order, the pseudo-second-order, and the intraparticle diffusion models. Equilibrium is reached after 30 min and 60 min for B-MTPB and B-NHTPB, respectively; the pseudo-second-order kinetic model described very well the adsorption of Orange II on modiﬁed bentonites. The non-linear Langmuir model provided the best correlation of experimental data, maximum adsorption of Orange II is 53.78 mgg_1 for B-NHTPB and 33.79 mg g_1 for B-MTPB. The thermodynamic parameters, such as free energy of adsorption (DG_), enthalpy change (DH_), and entropy change (DS_) were also determined and evaluated. From thermodynamic studies, it was deduced that the adsorption was spontaneous and exothermic.
Synthesis and characterization of Mg–Fe layer double hydroxides and its application on adsorption of Orange G from aqueous solution
(University of sciences and technology in Oran, 2015-03-09) Benselka-Hadj Abdelkader, Naima; A. Bentouami; Z. Derriche; N. Bettahar; L.-C. de Ménorval
Layered double hydroxide (LDH) with hydrotalcite-like structure containing Mg(II) and Fe(III) in the layers and its calcined form were prepared at different Mg/Fe molar ration by co-precipitation method at ﬁxed pH= 10 and followed by calcination at 500°C (denoted CLDH). The obtained materials were characterized by powder X-ray diffraction (PXRD), FT-IR spectroscopy, and TGA. The prepared LDH and CLDH were used for Orange G (Acid Orange 10) dye removal from aqueous solutions. Batch studies were carried out to address various experimental parameters such as contact time, pH, sorbent dose and temperature. The sorption kinetics data ﬁtted the pseudo-second order model. The isotherms were established and the parameters calculated. The sorption data ﬁtted the Langmuir model with good values of the correlation coefﬁcient. The sorption capacity of CLDH was found to be almost independent on initial pH of solution in the range 3–13 and approximately 5 times higher than that of LDH.
Thermal stability and structural characteristics of PTHF–Mmt organophile nanocomposite
(University of sciences and technology in Oran, 2015-04-20) Hattab, Youcef; Benharrats, Nassira
Polymer nanocomposites represent a new class of material alternative to conventionally ﬁlled polymers. This new class of material is synthesized from a mixed polymeric matrix at a weak percentage with ontmorillonites as inorganic charges. Their dispersion is facilitated by the organophilization of their structure by the exchange of inside foliar cations with compatilization possessed at once hydrophiles and hydrophobes ends, respectively, to be compatible with clay and polymer. The objective of this study is to use organophilized montmorillonites in the presence of monomer tetrahydrofuran to obtain polytétrahydrofuran montmorillonites (PTHF–Mmt) of composites by polymerization in situ. The organophilisation of the Mmt is formed by active cationic surface.The obtained results show an increase in the distance inside the reticular in the diffractograms of X-rays (DRX) and the appearance of absorption bands of the characteristics of polytétrahydrofuran on the spectra of infrared spectroscopy (IR), which indicate pre-polymerization of tetrahydrofuran in the galleries of clay and, therefore, the obtaining of a nanocomposite. We have also studied the thermal stability of the samples by differential analysis calorimetric (DSC) analysis, and we can conclude that the nanocomposites are stabilized thermally by the presence of clay in the matrix. 2011 King Saud University. Production and hosting by Elsevier B.V. All rights reserved
β-diketone functionalized SBA-15 and SBA-16 for rapid liquid–solid extraction of copper
(University of sciences and technology in Oran, 2015-05-13) R. Ouargli; R. Hamacha; N. Benharrats; A. Boos; A. Bengueddach
b-diketone functionalized SBA mesoporous materials were used successfully for the removal of copper from aqueous solution. SBA-15 and SBA-16 were impregnated with an acid ligand, 1-phenyl-3-methyl-4-stearoyl-5-pyrazolone (HPMSP) via the wet impregnation method. Characterization techniques showed that the highly ordered structure of the functionalized SBA is well retained after impregnation by the HPMSP. The effect of different extraction parameters, such as equilibrium time, extraction rate as a function of pH, nature of the medium (presence of NO 3- or SO4 2-) and the extraction capacity has been studied and discussed. A copper uptake close to 99.99 % for functionalized SBA-15 and SBA-16 was achieved within only 5 min at lower pH values, thus the extraction kinetics are very rapid and instantaneous as attested by the immediate green coloration of the materials when mixed with copper solution. The extraction capacities of copper were determined about 22 and 25 mg/g at pH 3 respectively for SBA-15 CI and SBA-16 CI and ﬁts well to the Langmuir isotherm equation.