Stability of supported ionic liquid membranes as studied by X-ray photoelectron spectroscopy

Fortunato, Raquel; Afonso, Carlos A. M.; Benavente, J.; Rodríguez‐Castellón, Enrique; Crespo, João G.

doi:10.1016/j.memsci.2005.02.023

Cited by 31 publications

(38 citation statements)

References 21 publications

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“…Importantly, although water was found to be partly soluble in the ionic liquids studied, displacement of ionic liquid from the membrane pores did not occur giving the SLM high operational stability. The high stability in aqueous systems was further confirmed by X-ray photoelectron spectroscopy (XPS) [39], which only revealed depletion of excess ionic liquid present on the membrane surface under fast recirculation conditions. Examination of stability and transport properties of SILMs based on porous, hydrophilic polyethersulfone and water stable ionic liquids [EMIM][X] (X = (CF 3 SO 3 ) 2 N, CF 3 SO 3 , (CN) 2 N) and [Hex 3 TetradecylP]Cl has also been explored as materials for acid gas separations of CO 2 from nitrogen and methane, respectively [40].…”

Section: Supported Ionic Liquid Membranes (Silms) For Separationsmentioning

confidence: 95%

Supported ionic liquids: versatile reaction and separation media

et al. 2006

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The latest developments in supported ionic liquid phase (SILP) systems for catalysis and separation technology are surveyed. The SILP concept combines the advantages of homogeneous catalysis with heterogeneous process technology, and a variety of reactions have been studied where supported ionic liquid catalysts proved to be more active and selective than common systems. In separation applications the use of supported ionic liquids can facilitate selective transport of substrates across membranes.

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Section: Supported Ionic Liquid Membranes (Silms) For Separationsmentioning

confidence: 95%

Supported ionic liquids: versatile reaction and separation media

et al. 2006

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“…A Shirley-type background was subtracted from the signals. Recorded spectra were always fitted using Gauss-Lorentz curves and following the methodology described in detail elsewhere [24], in order to determinate more accurately the binding energy (BE) of the different element core levels. Atomic concentration percentages of the characteristic elements of the surfaces were determined taking into account the corresponding area sensitivity factor [25] for the different measured spectral regions.…”

Section: Xps Measurementsmentioning

confidence: 99%

“…However, a more reduced number of papers on surface study of both original and modified membranes are published, although membrane surface represents the interface between two different transport media, which can be solid/solid in the case of fuel cells or solid/liquid when supported liquid membranes (SLMs) or other electrochemical devices proposed for selective solute separation are considered [15,24,25].…”

Section: Introductionmentioning

confidence: 99%

Modification of Nafion Membranes by IL-Cation Exchange: Chemical Surface, Electrical and Interfacial Study

Romero

Yuso

Arango

et al. 2012

International Journal of Electrochemistry

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Bulk and surface changes in two proton-exchange membranes (Nafion-112 and Nafion-117) as a result of the incorporation of the IL-cation n-dodecyltriethylammonium (or DTA + ) by a proton/cation exchange mechanism after immersion in a DTA + aqueous solution were analysed by impedance spectroscopy (IS), differential scanning calorimetry (DSC), X-ray photoelectron spectroscopy (XPS), and contact angle measurements performed with dry samples of the original Nafion and Nafion-DTA + -modified membranes. Only slight differences were obtained in the incorporation degree and surface chemical nature depending on the membrane thickness, and DTA + incorporation modified both the hydrophobic character of the original Nafion membranes and their thermal stability. Electrical characterization of the dry Nafion-112 membrane was performed by impedance spectroscopy while different HCl solutions were used for membrane potential measurements. A study of time evolution of the impedance curves measured in the system "IL aqueous solution/Nafion-112 membrane/IL aqueous solution" was also performed. This study allows us monitoring the electrical changes associated to the IL-cation incorporation in both the membrane and the membrane/IL solution interface, and it provides supplementary information on the characteristic of the Nafion/DTA + hybrid material. Moreover, the results also show the significant effect of water on the electrical resistance of the Nafion-112/IL-cation-modified membrane.

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“…This technique allows the determination of the surface chemical composition of a given sample and other properties related to the structure and chemical environment in which the atom lies within the solid and, in the case of membranes, it is commonly used to study chemical changes in polymer matrix [13,14]. Impedance spectroscopy (IS) measurements were performed for electrical characterization of dry IL-doped membranes by analyzing the impedance plots and using equivalent circuits as models [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Chemical Surface, Thermal and Electrical Characterization of Nafion Membranes Doped with IL-Cations

et al. 2014

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Surface and bulk changes in a Nafion membrane as a result of IL-cation doping (1-butyl-3-methylimidazolium tetrafluoroborate or BMIM + BF 4 and phenyltrimethylammonium chloride or TMPA + Cl − ) were studied by X-ray photoelectron spectroscopy (XPS), contact angle, differential scanning calorimetry (DSC) and impedance spectroscopy (IS) measurements performed with dry samples after 24 h in contact with the IL-cations BMIM + and TMPA + . IL-cations were selected due to their similar molecular weight and molar volume but different shape, which could facilitate/obstruct the cation incorporation in the Nafion membrane structure by proton/cation exchange mechanism. The surface coverage of the Nafion membrane by the IL-cations was confirmed by XPS analysis and contact angle, while the results obtained by the other two techniques (DSC and IS) seem to indicate differences in thermal and electrical behaviour depending on the doping-cation, being less resistive the Nafion/BMIM + membrane. For that reason, determination of the ion transport number was obtained for this membrane by measuring the membrane or concentration potential with the samples in contact with HCl solutions at different concentrations. The comparison of these results with those obtained for the original Nafion membrane provides information on the effect of IL-cation BMIM + on the transport of H + across wet Nafion/BMIM + doped membranes. OPEN ACCESSAppl. Sci. 2014, 4 196

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Stability of supported ionic liquid membranes as studied by X-ray photoelectron spectroscopy

Cited by 31 publications

References 21 publications

Supported ionic liquids: versatile reaction and separation media

Supported ionic liquids: versatile reaction and separation media

Modification of Nafion Membranes by IL-Cation Exchange: Chemical Surface, Electrical and Interfacial Study

Chemical Surface, Thermal and Electrical Characterization of Nafion Membranes Doped with IL-Cations

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