Measurement of Dynamic Transport Number in Ion-exchange Membrane by Limiting Current Method with Microhole Filter

DOI Web Site 1 Citations 13 References
  • SUDOH Masao
    Department of Materials Science and Chemical Engineering, Shizuoka University
  • INAMI Eiji
    Department of Materials Science and Chemical Engineering, Shizuoka University

Bibliographic Information

Other Title
  • 微孔膜限界電流値法によるイオン交換膜の動的輸率測定法
  • ビコウマク ゲンカイ デンリュウチホウ ニ ヨル イオン コウカンマク ノ ド

Search this article

Abstract

The dynamic transport number of counter-ions in Nafion-117 was measured by the limiting current method with a microhole filter. The microhole filter was attached onto the anode side of the Nafion surface in order to fix the thickness of the fluid film. The limiting currents were affected by various conditions of the measurement. A scanning rate of below 10mV/s was required to maintain a steady-state concentration in the laminar film. A scanning rate of above 3mV/s was required to prevent concentration differences between opposite sides of the membrane. Since the porosity of microhole Nuclepore filters decreases with a decrease in pore diameter, the electrical resistance of the microhole filter significantly affected the voltage difference in cases where the pore diameter was below 0.05μm (the porosity below 0.01). Mean while, in case where the pore diameter was above 0.2μm, ionic transport through the microhole filter was not rate-determining. The limiting current was increased by stirring the external solution, because the flux was disturbed and the membrane vibrated. In conclusion, a pore diameter (microhole filter) of 0.08μm, a scanning rate of 5mV/ s and no stirring are the most optimum conditions. The transport number of counter-ions (H+ or Na+) through Nafion-117 decreased by the intrusion of co-ions with increasing external concentration. Non-homogeneity β was obtained as from 0.1 to 0.2 by analyzing the two phase model of ionic transport of H+and Na+, respectively. The measurement of the anion sorbed concentration yielded high non-homogeneity (β= 0.4). It is believed that the large volume of ion-clusters of Nafion was related to the anion-sorbed concentration and the small channels between ion-clusters controlled the transport of the counter-ion.

Journal

Citations (1)*help

See more

References(13)*help

See more

Details 詳細情報について

Report a problem

Back to top