Counter-ions diffusion properties of silica embedded poly(perfluorosulfonic) acid membrane
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Title |
Counter-ions diffusion properties of silica embedded poly(perfluorosulfonic) acid membrane
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Creator |
CHAUDHURY, S
AGARWAL, C PANDEY, AK AHER, VT PANICKER, L RAMAGIRI, SV BELLARE, JR GOSWAMI, A |
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Subject |
PERFLUORINATED IONOMER MEMBRANES
WATER TRANSPORT CHARACTERISTICS NAFION MEMBRANES EXCHANGE MEMBRANE SELF-DIFFUSION SILVER NANOPARTICLES COMPOSITE MEMBRANES OXIDE NANOPARTICLES FUEL-CELLS CATIONS Nafion-117 Silica nanoparticles Self-diffusion coefficient Radiotracers Specific conductivity |
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Description |
To study the possibility of modifying diffusional-transport properties of the poly(perfluorosulfonic) acid (Nafion-117) membrane, the silica particles were incorporated in its matrix by in situ sol-gel method. The amount of silica incorporated in the membrane samples was varied by controlling the equilibrating time of the membrane sample in solution containing fixed proportion of precursor tetraethylorthosilicate (TEOS), methanol and water. The silica contents in the membrane samples were characterized by gravimetry, energy dispersive X-ray analysis (EDXRF) and transmission electron microscopy (TEM). Differential scanning calorimetry (DSC) studies showed that there were no significant difference in transition peak temperatures of both samples (Nafion-117 and Nafion/SiO(2)) in same ionic form except that enthalpies were increased in Nafion/SiO(2) samples in all the ionic forms. The increase in enthalpy was due to higher water content in Nafion/SiO(2) as compared to Nafion-117 in given ionic form as enthalpies normalized with water content of the respective membrane were comparable. The ion-exchange capacity, water uptake capacity and ion-exchange isotherms of the Na(+) + Cs(+) and Na(+) + Ba(2+) binary systems in silica embedded membrane samples were experimentally measured using appropriate radiotracers, and compared with that of pristine Nafion-117 membrane. The specific conductivities of the membrane samples with and without silica were studied in Na(+), Cs(+) and Ba(2+) ionic forms by electrochemical impedance spectroscopy (EIS). The self-diffusion coefficients of Na(+), Cs(+) and Ba(2+) ions in the Nafion/SiO(2) were measured by the radiotracer method. It was observed from the experimentally measured specific conductivities and self-diffusion coefficients data that diffusion mobility of Cs(+) and Ba(2+) counter-ions were enhanced significantly after incorporation of SiO(2) in the Nafion-117 matrix. Contrary to this, diffusion mobility of Na(+). counter-ion decreased in Nafion/SiO(2) sample. The selectivity of Cs(+) and Ba(2+) counter-ions was reduced in Nafion/SiO(2) sample with respect to pristine Nafion-117. (C) 2011 Elsevier B.V. All rights reserved.
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Publisher |
ELSEVIER SCIENCE BV
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Date |
2012-06-26T07:39:39Z
2012-06-26T07:39:39Z 2011 |
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Type |
Article
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Identifier |
JOURNAL OF MEMBRANE SCIENCE,382(1-2)262-270
0376-7388 http://dx.doi.org/10.1016/j.memsci.2011.08.018 http://dspace.library.iitb.ac.in/jspui/handle/100/14158 |
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Language |
English
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