Sainte-Foy-lès-Lyon, France
Sainte-Foy-lès-Lyon, France
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Lucazeau G.,LEPMI | Le Bacq O.,SIMAP | Pasturel A.,SIMAP | Pasturel A.,French National Center for Scientific Research | And 2 more authors.
Journal of Raman Spectroscopy | Year: 2011

Polarized Raman spectra of a single crystal of gadolinium molybdate [Gd2(MoO4)3] were obtained between 1 atm and 7 GPa. Using a mixture of alcohols as the pressure-transmitting medium, YY, ZZ, XY components of scattering matrices were measured. The ZZ spectra were also obtained in argon. Five phase transitions and amorphization were identified. The first and second transitions are reversible, while amorphization is not. In alcohol, amorphization is observed above 6.5 GPa. With argon as the pressure-transmitting medium, amorphization is progressive and begins above 3 GPa. The spectral changes with pressure affect the high wavenumber bands attributed to symmetric and antisymmetric MoO4 stretching modes as well as the very low wavenumber modes such as librations of the tetrahedra. This means that both short-range and long-range organizations of the tetrahedra are involved in these phase transitions. The amorphization mechanism and its dependence on the pressure-transmitting medium are discussed, and the steric hindrance between polyhedra is believed to be the most relevant mechanism. The TO and LO low wavenumber modes of A1 symmetry, observed in the Y(ZZ)Y and Z(YY)Z geometries, respectively, below 50 cm-1, soften continuously through the first three phases when increasing pressure. The strong A2 mode observed in the Z(XY)Z spectra exhibits the same anomalous behavior by decreasing from 53 to 46 cm-1 at 2 GPa. The softening of these modes is related to the orientation change of tetrahedra observed by ab initio calculations when the volume of the cell is decreased. These orientation changes can explain the wavenumber decrease of the Mo-O stretching modes above 2 GPa, which indicates an increase of Mo coordination. © 2010 John Wiley & Sons, Ltd.

Martinez M.,LEPMI | Molmeret Y.,CNRS Rheology Laboratory | Cointeaux L.,LEPMI | Iojoiu C.,LEPMI | And 4 more authors.
Journal of Power Sources | Year: 2010

The paper deals with the synthesis and characterisation of proton-conducting ionic liquids (PCILs) and their polymer electrolytes obtained by blending modified Nafion membranes with different concentrations of PCILs. The PCILs are obtained by the neutralization of triethylamine with different organic acids. The first part of the paper studies the influence of acidity and acid structure on PCIL thermal and electrochemical performance, while the second part examines membrane conductivity and reveals it to depend more on PCIL structure than on its intrinsic conductivity. At 130 °C, conductivities exceeding 10 mS cm-1 were obtained in fully anhydrous conditions. © 2010 Elsevier B.V. All rights reserved.

Soupremanien U.,LEGI | Person S.L.,LEGI | Favre-Marinet M.,LEGI | Bultel Y.,LEPMI
Experimental Thermal and Fluid Science | Year: 2011

This article presents experiments conducted with two single rectangular mini-channels of same hydraulic diameter (1.4mm) and different aspect ratios for conditions of horizontal boiling flow. The Forane® 365 HX used was subcooled (ΔTsub=15°C) for all the boiling curves presented in the paper. Local heat transfer coefficients were measured for heat flux ranging from 25 to 62kWm-2 and mass flux from 200kgm-2s-1 to 400kgm-2s-1. The boiling flows were observed with two different cameras (depending on the flow velocity) through a visualization window. The flow patterns in the two channels were compared for similar conditions. The results show that the boiling heat transfer coefficient and the pressure drop values are different for the two single mini-channels. For low heat flux condition, the channel with lowest aspect ratio (H/W=0.143) has a higher heat transfer coefficient. On the other hand, for high heat flux condition, the opposite situation occurs, namely the heat transfer coefficient becomes higher for the channel with highest aspect ratio (H/W=0.43). This is probably due to the earlier onset of dryout in the channel with lowest aspect ratio. For the two cases of heating, the pressure drop for the two-phase flow remains lower for the channel with lowest aspect ratio. These results show that the aspect ratio plays a substantial role for boiling flows in rectangular channels. As for single-phase flows, the heat transfer characteristics are significantly influenced (even though the hydraulic diameter remains the same) by this parameter. © 2010 Elsevier Inc.

Chiha M.,Annaba University | Hamdaoui O.,Annaba University | Baup S.,LEPMI | Gondrexon N.,LEPMI
Ultrasonics Sonochemistry | Year: 2011

The sonolytic degradation of endocrine disrupting compound 4-cumylphenol (4-CyP) in aqueous solution was investigated. The influence of operating parameters for sonication process such as 4-CyP initial concentration, frequency, power, pH, temperature and saturating gas was examined. The extent of degradation was inversely proportional to the initial substrate concentration. The rate of 4-CyP degradation was frequency dependent. The degradation rate increased proportionally with increasing ultrasonic power from 20 to 100 W and temperature in the range of 20-50°C. The most favorable degradation pH was acidic media. Destruction in the presence of saturating gas follows the order: argon > air > nitrogen. The 4-CyP degradation was inhibited in the presence of nitrogen gas owing to the free radical scavenging effect in vapor phase within the bubbles of cavitation. The ultrasonic degradation of 4-CyP was clearly promoted in the presence of bromide anions and the promoting effect on degradation increased with increasing bromide concentration. At low 4-CyP concentration (0.05 mg L -1), bicarbonate ion drastically enhanced the rate of 4-CyP degradation. Experiments conducted using pure and natural water demonstrated that the sonolytic treatment was more efficient in the natural water compared to pure water. © 2010 Elsevier B.V. All rights reserved.

Leveque J.-M.,University of Savoy | Leveque J.-M.,Shiga University of Medical Science | Fujita M.,Shiga University of Medical Science | Bosson A.,University of Savoy | And 4 more authors.
Ultrasonics Sonochemistry | Year: 2011

The Molybdate-catalyzed bromination of various aromatic compounds in the presence of KBr/H2O2 in an aqueous/chloroform biphasic system occurred under ultrasonic irradiation, whereas the reaction did not take place under conventional mechanical stirring (1400 rpm). The sonochemical activation was found to be of secondary effect, attributed to lowering pH by sonolysis of CHCl3-H2O solvents mixture. © 2010 Elsevier B.V.

Vivet A.,Limoges National Superior School of Industrial Ceramics | Vivet A.,Air Liquide | Geffroy P.M.,Limoges National Superior School of Industrial Ceramics | Coudert V.,Limoges National Superior School of Industrial Ceramics | And 3 more authors.
Journal of Membrane Science | Year: 2011

Gas dissociation with a ceramic membrane is an economical and environmental attractive process for methane gas conversion into syngas (mixture of H2 and CO). For this application, the membrane materials require mixed ionic and electronic conductivities in a large range of pO2 resulting in an excellent oxygen semi-permeation of the membrane to improve methane conversion. In this paper, particular attention is given to the influence of sealant materials on oxygen semi-permeation performances of membrane materials. For instance, oxygen semi-permeation measurements have been performed with La0.8Sr0.2Fe0.7Ga0.3O3-δ membranes under an oxygen partial pressure gradient at temperatures from 700°C to 1000°C with different sealing materials (glass or gold ring sealant) between the membrane and the support. The result leads to a better understanding of the effects of sealing on oxygen transport through the La0.8Sr0.2Fe0.7Ga0.3O3-δ membrane. Indeed, a gold sealing material is required for accurate measurements of oxygen semi-permeation flux. © 2010 Elsevier B.V.

Chiha M.,Annaba University | Hamdaoui O.,Annaba University | Baup S.,LEPMI | Gondrexon N.,LEPMI | Petrier C.,LEPMI
Separation Science and Technology | Year: 2010

The aim of this work was to evaluate the influence of mineral and organic matrices on the sonochemical degradation of 4-isopropyl-phenol (4-IPP), an endocrine disrupting chemical found in water. Bicarbonate ions as mineral matrix and sucrose as organic competitor were evaluated with respect to their effect on sonochemical degradation rates. At low 4-IPP concentration, the sonolytic degradation was clearly improved in the presence of bicarbonate involving the formation of the carbonate radical resulting from the reaction of bicarbonate with hydroxyl radical. In the presence of large excess of sucrose, the sonochemical degradation of 4-IPP at low concentration was not affected. © Taylor & Francis Group, LLC.

Chiha M.,Laboratory of Environmental Engineering | Merouani S.,Laboratory of Environmental Engineering | Hamdaoui O.,Laboratory of Environmental Engineering | Baup S.,LEPMI | And 2 more authors.
Ultrasonics Sonochemistry | Year: 2010

Sonochemical degradation of phenol (Ph), 4-isopropylphenol (4-IPP) and Rhodamine B (RhB) in aqueous solutions was investigated for a large range of initial concentrations in order to analyze the reaction kinetics. The initial rates of substrate degradation and H2O2 formation as a function of initial concentrations were determined. The obtained results show that the degradation rate increases with increasing initial substrate concentration up to a plateau and that the sonolytic destruction occurs mainly through reactions with hydroxyl radicals in the interfacial region of cavitation bubbles. The rate of H2O2 formation decreases with increasing substrate concentration and reaches a minimum, followed by almost constant production rate for higher substrate concentrations. Sonolytic degradation data were analyzed by the models of Okitsu et al. [K. Okitsu, K. Iwasaki, Y. Yobiko, H. Bandow, R. Nishimura, Y. Maeda, Sonochemical degradation of azo dyes in aqueous solution: a new heterogeneous kinetics model taking into account the local concentration OH radicals and azo dyes, Ultrason. Sonochem. 12 (2005) 255-262.] and Seprone et al. [N. Serpone, R. Terzian, H. Hidaka, E. Pelizzetti, Ultrasonic induced dehalogenation and oxidation of 2-, 3-, and 4-chlorophenol in air-equilibrated aqueous media. Similarities with irradiated semiconductor particulates, J. Phys. Chem. 98 (1994) 2634-2640.] developed on the basis of a Langmuir-type mechanism. The five linearized forms of the Okitsu et al.'s equation as well as the non-linear curve fitting analysis method were discussed. Results show that it is not appropriate to use the coefficient of determination of the linear regression method for comparing the best-fitting. Among the five linear expressions of the Okitsu et al.'s kinetic model, form-2 expression very well represent the degradation data for Ph and 4-IPP. Non-linear curve fitting analysis method was found to be the more appropriate method to determine the model parameters. An excellent representation of the experimental results of sonolytic destruction of RhB was obtained using the Serpone et al.'s model. The Serpone et al.'s model gives a worse fit for the sonolytic degradation data of Ph and 4-IPP. These results indicate that Ph and 4-IPP undergo degradation predominantly at the bubble/solution interface, whereas RhB undergoes degradation at both bubble/solution interface and in the bulk solution. © 2010 Elsevier B.V. All rights reserved.

Assumma L.,University of GrenobleF 38000Grenoble France | Iojoiu C.,University of GrenobleF 38000Grenoble France | Mercier R.,University of Lyon | Lyonnard S.,CNRS Structure and Properties of Molecular Architectures Laboratory | And 2 more authors.
Journal of Polymer Science, Part A: Polymer Chemistry | Year: 2015

Partially fluorinated poly(arylene ether sulfone) multiblock copolymers bearing perfluorosulfonic functions (ps-PES-FPES), with ionic exchange capacity (IEC) ranging between 0.9 and 1.5 meq H+/g, are synthesized by regioselective bromination of partially fluorinated poly(arylene ether sulfone) multiblock copolymers (PES-FPES), followed by Ullman coupling reaction with lithium 1,1,2,2-tetrafluoro-2-(1,1,2,2-tetrafluoro-2-iodoethoxy)ethanesulfonate. The PES-FPES are prepared by aromatic nucleophilic substitution reaction by an original approach, that is, "one pot two reactions synthesis." The chemical structures of polymers are analyzed by 1H and 19F NMR spectroscopy. The resulted ionomers present two distinct glass transitions and α relaxations revealing phase separation between the hydrophilic and the hydrophobic domains. The phase separation is observed at much lower block lengths of ps-PES-FPES as compared with the literature. AFM and SANS observations supported the phase separation, the hydrophilic domains are well dispersed but the connectivity to each other depends on the ps-PES block lengths. The thermomechanical behavior, the water up-take, and the conductivity of the ps-PES-FPES membranes are compared with those of Nafion 117® and randomly functionalized polysulfone (ps-PES). Conductivities close or higher to those of Nafion 117® are obtained. © 2015 Wiley Periodicals, Inc.

El Baradai O.,Electronic and microelectronic center | Beneventi D.,Greek National Center For Scientific Research | Alloin F.,French National Center for Scientific Research | Bultel Y.,LEPMI | And 2 more authors.
International Journal of Engineering and Technology Innovation | Year: 2015

Organic free electrodes for lithium ion batteries containing cellulose derivatives components as binding and disperser respectively, lithium iron phosphate as active material and carbon black as conductive agent were manufactured by means of a large scale technique as well as screen printing process onto a cellulosic based separator. Firstly a water based ink, was formulated and rheological properties were analyzed in order to investigate the role of each component in the ink. Electrical conductivity was tuned by adjusting the content of carbon black to insure electrical percolation. The electrode exhibits a capacity of 143 mAh/g at C/10, close to the nominal capacity of the lithium iron phosphate (150 mAh/g). At higher current rates a good retention capacity was observed with 107 mAh/g at C. Finally industrial scale printed electrodes were manufactured by means of an industrial printing machine onto a cellulose based separator. The electrodes exhibit a promising capacity of 129 mAh/g at C/10 and an electrical conductivity of 21 S/m. The industrial scale approach proposed here could be a viable route to the manufacturing of large scale and eco-sustainable electrodes. © 2015.

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