Murviel-lès-Montpellier, France
Murviel-lès-Montpellier, France

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Merian T.,University of Maine, France | Debarnot D.,University of Maine, France | Rouessac V.,Institute Europeen des Membranes | Poncin-Epaillard F.,University of Maine, France
Talanta | Year: 2010

The ammonia absorption properties of polyaniline elaborated by the pulsed-plasma technique are studied. These properties depend on the structure of the polymer which is associated not only to plasma parameters such as peak power, ignition and extinction durations, pulse frequency and duty cycle, but also to the type of doping agent. Two methods of analysis are used: the UV/vis spectrometry and the quartz crystal microbalance. The results show that input power is the most influent plasma parameter on the sensitivity of the polyaniline film. Moreover, the oxidative doping is more efficient than the acidic one to create more polarons and then to obtain a more sensitive layer. The gravimetric study shows that the interaction between ammonia molecules and iodine-doped polyaniline corresponds to a multilayer reversible chemisorption. © 2010 Elsevier B.V. All rights reserved.

Kujawa J.,Nicolaus Copernicus University | Cerneaux S.,Institute Europeen des Membranes | Kujawski W.,Nicolaus Copernicus University
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2014

Four types of perfluoroalkylsilanes (PFAS) molecules with various lengths of fluorocarbon chains were used to modify Al2O3, TiO2 and ZrO2 powders. The surface grafting process was examined by 29Si NMR, TGA and FT-MIR techniques. Results reveal three possible types of bonding of the hydrophobic chains to the metal oxide surface. Moreover, it was established that the type of PFAS molecules and the type of modified surface have a strong influence on the mode and amount of hydrophobic molecules anchored to the surface. It was observed that alumina oxide is modified with the highest efficiency. The fraction of OH surface groups utilized during grafting of Al2O3 by C6, C8 and C10 are similar (64-68%), but for samples grafted by C12 are much lower (40%). The PFAS molecules with shorter fluorocarbon chains (C6 and C8) are attached mainly by siloxane (T3) and geminal silanol bonds (T2), whereas longer chains (C10 and C12) are attached generally by single (T1) and geminal silanol (T2) bonds. The hindrance steric effect is observed for powder samples grafted by C12 molecules.Additionally the influence of contact with water and butanol on the conformational orientation of PFAS was evaluated. It was found, that in contact with water molecules, PFAS chains are in a tangled form, whereas in contact with butanol molecules the grafted chains are straightened. © 2014 Elsevier B.V.

Kujawa J.,Nicolaus Copernicus University | Rozicka A.,Nicolaus Copernicus University | Cerneaux S.,Institute Europeen des Membranes | Kujawski W.,Nicolaus Copernicus University
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2014

Titania ceramic membranes were efficiently modified with perfluoroalkylsilanes (PFAS). PFAS compounds with different length of fluorine alkyl chain (in the range of 6-12 carbon atoms in chain) were used during experiments. Grafting process efficiency was determined by contact angle measurements of water and glycerol. The highest hydrophobicity was obtained for the membrane grafted by C12-after 53h of modification. The contact angle value was equal to 136̊. The least efficient modification was obtained for the membrane grafted with C8, the contact angle was equal to 126̊ after 53h of grafting. The contact angle measurements with bipolar substance (glycerol) were also carried out in order to apply the Owens-Wendt method for the determination of the surface free energy (SFE) values of modified membranes. The different mode of PFAS chains attachment to the membrane surface was observed. This phenomena was related to different structure of grafting molecules. The hindrance steric effect was observed for more hydrophobic molecules (C10, C12). The surface grafting process was characterized applying 29Si NMR and TGA techniques. According to obtained results, three possible types of bonding of the hydrophobic chains to the materials surface were determined. Additionally, based on the results, it was found that type of PFAS molecule has a strong influence on the mode of anchored hydrophobic molecules to the surface. It was found that PFAS molecules with shorter fluorocarbon chains are attached mainly by siloxane (T3) and geminal silanol bonds (T2), whereas longer chains are attached mainly by single (T1) and geminal silanol (T2) bonds. © 2013 Elsevier B.V.

Kujawa J.,Nicolaus Copernicus University | Cerneaux S.,Institute Europeen des Membranes | Kujawski W.,Nicolaus Copernicus University
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2014

Tubular and planar ceramic titania membranes as well as metal oxide powders (Al2O3, TiO2 and ZrO2) were modified by various perfluoroalkylsilanes molecules. During the modification process, the hydrophobic layer on the membrane or powder surface was created. Grafting efficiency was determined by liquid entry pressure (LEPw), contact angle or FT-MIR analysis. Subsequently grafted samples were exposed to air (2 years) or water (1 year), to evaluate the stability of hydrophobic layer with time. The chemical and thermal stability of modified powders and membranes was also estimated. Moreover, the tubular membranes of various porosity were tested in pervaporation (PV) and air-gap membrane distillation (AGMD) process after 2 years exposure to the air since grafting. The modified powders were thermally stable up to temperature of 250. °C. However, the grafted metal oxide powders were not stable in alkaline solutions at pH > 12.Furthermore, the metal oxide powders and the planar membranes were also stable in organic solvents like hexane or chloroform. Moreover, a significant decrease of contact angle from 132° to 62° was observed after 1 year of contact with water for planar membrane grafted by C10 molecules. An important impact on the transport properties of pure water in PV and AGMD after 2 years contact with air was also observed. In PV, the water flux decreased from 1200gh-1m-2 to 430gh-1m-2 for Ti-5nm-C8 membrane. AGMD the water fluxes decreased by 21% and 27% for Ti-300kD-C6 and Ti-300kD-C12 membranes, respectively. © 2013 Elsevier B.V.

Kujawa J.,Nicolaus Copernicus University | Cerneaux S.,Institute Europeen des Membranes | Kujawski W.,Nicolaus Copernicus University
Journal of Membrane Science | Year: 2015

Hydrophobic alumina and titania micro and mesoporous ceramic membranes were prepared by grafting of C6F13C2H4Si(OEt)3 (C6) molecules and subsequently applied in a pervaporation (PV) process to the removal of hazardous organic solvents (MTBE, EtAc and BuOH) from binary aqueous solutions. The transport and separation properties of investigated membranes were discussed. Additionally it was found that membrane material and grafting time have an important impact of the pervaporative properties. All tested membranes were selective toward organics. Titania membrane was the most efficient and was characterized by the highest value of PSI and the highest value of permeate flux of organic compounds in water-EtAc (JEtAc=1.1kgh-1m-2; PSIEtAc=140kgh-1m-2) and water-MTBE (JMTBE=1.0kgh-1m-2; PSIMTBE=194kgh-1m-2) systems. This behavior of titania membrane was also discussed based on the Hansen solubility parameters. In presented work the evaluation of MTBE removal degree with titania modified membrane from water binary mixture in the pervaporation process was discussed. © 2014 Elsevier B.V..

Escande V.,French National Center for Scientific Research | Olszewski T.K.,Wroclaw University of Technology | Petit E.,Institute Europeen des Membranes | Grison C.,French National Center for Scientific Research
ChemSusChem | Year: 2014

Polymetallic hyperaccumulating plants growing on wastes from former mining activity were used as the starting material in the preparation of novel plant-based Lewis acid catalysts. The preparation of biosourced Lewis acid catalysts is a new way to make use of mining wastes. These catalysts were characterized by X-ray fluorescence, X-ray diffraction, inductively coupled plasma mass spectrometry, and direct infusion electrospray ionization mass spectrometry. These analyses revealed a complex composition of metal species, present mainly as polymetallic chlorides. The catalysts proved to be efficient and recyclable in a solid-state version of the Garcia Gonzalez reaction, which has been underexploited until now in efforts to use carbohydrates from biomass. This methodology was extended to various carbohydrates to obtain the corresponding polyhydroxyalkyl furans in 38-98 % yield. These plant-based catalysts may be a better alternative to classical Lewis acid catalysts that were previously used for the Garcia Gonzalez reaction, such as ZnCl2, FeCl3, and CeCl3, which are often unrecyclable, require aqueous treatments, or rely on metals, the current known reserves of which will be consumed in the coming decades. Moreover, the plant-based catalysts allowed novel control of the Garcia Gonzalez reaction, as two different products were obtained depending on the reaction conditions. Common-or-garden variety catalyst: Polymetallic hyperaccumulating plants are used in the preparation of Lewis acid plant-based catalysts. The catalysts efficiently mediate the Garcia Gonzalez reaction to furnish platform molecules from carbohydrates. Efficiency, generality of application, ease of control of the reaction selectivity, use of solid-state reactions, and the capacity to recover and reuse polymetallic catalysts are the key advantages of the presented approach. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Habrioux A.,University of Poitiers | Napporn T.,University of Poitiers | Servat K.,University of Poitiers | Tingry S.,Institute Europeen des Membranes | Kokoh K.B.,University of Poitiers
Electrochimica Acta | Year: 2010

A new biocathode was built and tested. It consisted of bilirubin oxidase adsorbed on Vulcan XC 72 R and immobilized into a Nafion® matrix. The possibility of direct electron transfer between bilirubin oxidase and Vulcan XC 72 R was also demonstrated. The kinetics on biocathode were enhanced by including 2,2′-azinobis-3-ethylbenzothiazoline-5-sulfonic acid in the catalytic film. A first order reaction rate was observed for oxygen concentrations lower than 22%. A complete kinetic investigation of the system was shown. A biofuel cell test performed with this biocathode and Au 70Pt30 nanoparticles as anode catalyst permitted to reach a power density of 170 μW cm-2 at a cell voltage of 0.6 V, which is superior to what can be obtained with the concentric design. © 2009 Elsevier Ltd.

Rodriguez-Castillo M.,Charles Gerhardt Institute | Laurencin D.,Charles Gerhardt Institute | Tielens F.,CNRS Laboratory of Condensed Matter Chemistry, Paris | Van Der Lee A.,Institute Europeen des Membranes | And 3 more authors.
Dalton Transactions | Year: 2014

The reaction of gold nanoparticles with benzimididazol-2-ylidene ligands leads to the formation of well-defined bis-carbene gold(i) complexes, as shown by characterization techniques such as powder XRD and solid state NMR. This journal is © the Partner Organisations 2014.

Barboiu M.,Institute Europeen des Membranes | Barboiu M.,Petru Poni Institute of Macromolecular Chemistry
Chemical Communications | Year: 2016

Aquaporins (AQPs) are biological water channels known for fast water transport (∼108-109 water molecules per s per channel), with complete proton/ion exclusion. Few synthetic channels have been designed to mimic this high water permeability and to reject ions at a significant level. This Feature Article will discuss the incipient developments of the first artificial water channel systems. © The Royal Society of Chemistry 2016.

Ennajdaoui A.,Institute Europeen des Membranes | Roualdes S.,Institute Europeen des Membranes | Brault P.,University of Orléans | Durand J.,Institute Europeen des Membranes
Journal of Power Sources | Year: 2010

A plasma polymerization process using a continuous glow discharge has been implemented for preparing proton conducting membranes from trifluoromethane sulfonic acid and styrene. The chemical and physical structure of plasma membranes has been investigated using FTIR and SEM. The films are homogeneous with a good adhesion on commercial gas diffusion layer (E-Tek®). Their deposition rate can be increased with increasing flow rate and input power. The thermogravimetric analysis under air of plasma polymers has showed a thermal stability up to 140 °C. Compared to the pulsed glow discharge studied in a previous paper, the continuous glow discharge has enabled to enhance the proton conductivity of membranes by a factor 3 (up to 1.7 mS cm-1). Moreover, the low methanol permeability (methanol diffusion coefficient down to 5 × 10-13 m2 s-1) of membranes has been confirmed by this study. In an industrial context, a reactor prototype has been developed to manufacture by plasma processes all active layers of fuel cell cores to be integrated in original compact PEMFC or DMFC. © 2009 Elsevier B.V. All rights reserved.

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