BIOSORPTION OF METHYLENE BLUE FROM WASTE WATER USING LEBANESE CYMBOPOGON CITRATUS (CITRONNELLE)

The objective of this study was to investigate the possibility of using Lebanese Cymbopogon citratus stem as an alternative adsorbent for the removal of methylene blue from aqueous solutions. Different parameters such as the effect of initial concentration, pH, adsorbent dose, contact time and temperature were studied. Maximum adsorption capacity (61%) of MB was obtained at PH=6 an initial concentration 200 mg/L after 24h and at 25 ˚C. The adsorption isotherm was better described by a Freundlich model rather than a Langmiur model. Based on these results, it can be concluded that the stems of Cymbopogon citratus is effective as an alternative adsorbent for MB remediation in waste water

BIOSORPTION OF METHYLENE BLUE FROM WASTE WATER USING LEBANESE CYMBOPOGON CITRATUS (CITRONNELLE)

The objective of this study was to investigate the possibility of using Lebanese Cymbopogon citratus stem as an alternative adsorbent for the removal of methylene blue from aqueous solutions. Different parameters such as the effect of initial concentration, pH, adsorbent dose, contact time and temperature were studied. Maximum adsorption capacity (61%) of MB was obtained at PH=6 an initial concentration 200 mg/L after 24h and at 25 ˚C. The adsorption isotherm was better described by a Freundlich model rather than a Langmiur model. Based on these results, it can be concluded that the stems of Cymbopogon citratus is effective as an alternative adsorbent for MB remediation in waste water

Transport mechanisms in 8-tris-hydroxyquinoline aluminium (Alq3) electronic layers: a study by photodipolar absorption

International audienceThis paper describes the role of traps in the electronic conductivity of 8-tris-hydroxyquinoline aluminium in a conventional sandwich structure with indium tin oxide and aluminium electrodes. New results obtained by photodipolar absorption techniques and impedance spectroscopy are presented. The former method acts as a probe to highlight the role of traps. It is shown that optical pumping of electrons to trap levels gives a clear increase in dielectric absorption due to the reorientation of dipoles associated with trapped charges. The trap depth is estimated to be around Et= 0.19 eV, a value in good agreement with theoretical calculations and thermoluminescence measurements. The latter method permits a representation of the sample in terms of a circuit composed of a parallel capacitor (Cp) and resistor (Rp) both in series with a resistor Rs≈ 50 Ωlocated on the anode side. A logarithmic plot of Rp as a function of the dc bias voltage gives a linear law that is recognized, for the first time, to be a consequence of a trapped charge limited (TCL) current. The linearity can be improved by the introduction of a field-dependent mobility

Synthesis by ATRP of Polystyrene-b-Poly(4-vinylpyridine) and Characterization by Inverse Gas Chromatography

A linear diblock copolymer [Polystyrene-b-Poly(4-vinyl-pyridine)] (PS-b-P4VP) was successfully prepared through Atom Transfer Radical Polymerization (ATRP). This synthesis is performed in two successive steps: using the (1-bromoethyl) benzene as initiatorand and Hexamethyl tris [2(dimethylamino)ethyl] amine as ligands in a protic solvent. The first step of the synthesis allows the realization of block polystyrene having a terminal function; however, Bromine (Br) permits the grafting of the second successive block P4VP. RMN -1H demonstrates that the P4VP block has been grafted onto the PS block. The molecular weight of PS-b-P4VP is determined by size exclusion chromatography, and its thermal stability is examined by TGA. The surface and the thermodynamic properties of this copolymer are studied by inverse gas chromatography (IGC). The new Hamieh Model shows that the synthesized copolymer PS-P4VP has an amphoteric behavior with rather very basic character that is six times stronger than acidic character (in Lewis terms), reflected the presence of acidic and basic groups in the structure of the PS-P4VP copolymer, more particularly the presence of benzenic, methyl and vinylpyridine groups

Réalisation de diodes électroluminescentes souples et caractérisations.

Thèse d'Université de Limoge

Les ligands soufrés dans les métalloenzymes à cuivre (études à partir de quelques complexes modèles bioinspirés)

Dans ce travail divisé en trois parties, nous avons étudié le rôle des interactions métal-soufre présentes dans de nombreuses métalloprotéines à cuivre. Pour cela, différents complexes modèles de cuivre ont été préparés. Dans la partie J, nous avons décrit la synthése de deux nouveaux ligands tripodaux de type N2S2. A partir de ces ligands, nous avons synthétisé cinq complexes mononucléaires de Cu(I) et Cu(II). Nous avons étudié les comportements de ces complexes par diverses méthodes (RX, UV-Vis, RPE, Electrochimie). Nos résultats ont montré que ces complexes possèdent des potentiels rédox élevés, comparables à ceux des protéines à cuivre de type Dans la partie II, à partir d'un nouveau ligand tripodal N2(StBu)(SH) possédant une fonction thiolate et une fonction thioéther, nous avons préparé un nouveau complexe binucléaire de Cu(II), de type bis(J.1-thiolato). Ce mode de coordination a été rarement décrit dans la littérature; aussi la caractérisation complète de ce composé est d'un grand intérêt en relation avec l'étude des centres type CuA de la Cytochrome c oxydase et de la réductase de l'oxyde nitreux. Les points suivants ont été plus spécifiquement étudiés : i) l'étude approfondie de la signature RPE particulière de ce complexe, ii) la préparation par voie électrochimique et la caractérisation de l'espèce de valence mixte Cu(II)-Cu(I) correspondante. Dans la partie III, pour la première fois dans la littérature, nous avons élaboré deux nouveaux modèles binucléaires de Cu(II) dissymétriques dans le b de comprendre le rôle d'une liaison thioéther qui se trouve dans le site actif de la catéchol oxydase (enzyme à cuivre de type III).GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Réalisation de diodes électroluminescents souples et caractérisations

Des couches minces d'oxyde d'indium et d'étain (ITO) ont été obtenues par un procédé de dépôt IBS (Ion Beam Sputtering). Cette technique nous a permis d'élaborer des films d'ITO sur des substrats souples en polyéthylène téréphtalate (PET), dans des conditions douces de basses températures et répondant aux exigences des procédés de fabrication des composants optoélectroniques organiques. Dans le cas d'un dépôt d'ITO non thermiquement activé (20C) et assisté par -un flux d'oxygène (1 cm3/min), nous avons obtenu une transmission optique de l'ordre de 90% dans le visible, une résistivité de 10-3 cm, et une rugosité de surface inférieure à 1,5nm. Ainsi nous avons pu réaliser des diodes électroluminescentes organiques flexibles (FOLEDs) présentant de bonnes performances: une luminance crête de 12000 cd/m2 à une tension de 19V et un rendement lumineux maximum de l'ordre de 1 lm/W à une tension de 10V (ou un rendement en courant maximum de 4 cd/A à 14V) pour la structure PET(50 m)/ ITO(200nm)/TPD(40nm)/ Alq3(60nm)/Ca/Al.Indium-tin oxide (ITO) thin layers were obtained by an IBS (Ion Beam Sputtering) deposition process. This technology enabled us to elaborate ITO films on flexible substrates of polyethylene terephthalate (PET), under soft conditions of low temperatures and fulfilling the requirements of fabrication processes of the organic optoelectronic components. ln the case of an ITO deposition which was non thermally activated (20C) and assisted by an oxygen flow (1 cm3/min); we got an optical transmittance of about 90% in the visible, a resistivity of about 10-3 cm and a surface roughness lower than 1.5nm. Thus we could realise flexible organic light-emitting diodes (FOLEDs) showing good performances : a max luminance of 12000 cd/m2 at a voltage of 19V and a maximum luminous power efficiency of about 1 lm/W at a voltage of 10V (or a maximum current efficiency of 4 cd/A at 14V) for the (PET( 50 m)/ITO(200nm)/TPD(40nm)/ Alq3(60nm)/Ca/Al) structure.LIMOGES-BU Sciences (870852109) / SudocSudocFranceF

Field and temperature effects on the electronic mobility in Alq3 structures.

International audienc

ITO films realized at room-temperature by Ion Beam Sputtering for high-performance Flexible Organic Light-Emitting Diodes

International audienceIndium-tin oxide (ITO) thin layers are obtained by an IBS (Ion Beam Sputtering) deposition process. We elaborated ITO films on flexible substrates of polyethylene terephthalate (PET), under soft conditions of low temperatures and fulfilling the requirements of fabrication processes of the organic optoelectronic components. With a non thermally activated (20 °C) ITO deposition assisted by an oxygen flow (1 cm3/min), we got an optical transmittance of 90% in the visible range, a resistivity around 10-3 Ω.cm and a surface roughness lower than 1.5 nm. Thus we realized flexible organic light-emitting diodes (FOLEDs) with good performances: a maximum luminance of 12000 cd/m2 at a voltage of 19 V and a maximum luminous power efficiency around 1 lm/W at a voltage of 10 V (or a maximum current efficiency of 4 cd/A at 14 V) for the (PET(50 μ m)/ITO(200 nm)/TPD(40 nm)/Alq3(60 nm)/Ca/Al) structure