Ionic conductivity of ion-exchange membranes: Measurement techniques and salt concentration dependence
| Autor: | José C. Díaz, Jovan Kamcev |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
chemistry.chemical_classification
Materials science Analytical chemistry Salt (chemistry) Filtration and Separation 02 engineering and technology Electrolyte 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Biochemistry 0104 chemical sciences Dielectric spectroscopy Electrochemical cell Membrane chemistry Electrode Ionic conductivity General Materials Science Physical and Theoretical Chemistry 0210 nano-technology Ion transporter |
| Zdroj: | Journal of Membrane Science. 618:118718 |
| ISSN: | 0376-7388 |
| Popis: | Accurate measurements of membrane ionic conductivity are important for advancing the fundamental understanding of electric field-driven ion transport in ion-exchange membranes. There is no standardized technique for performing such measurements on membranes equilibrated with salt solutions, despite a longstanding interest in this topic. As a result, discrepancies between reported ionic conductivity values for common commercial membranes are often found in the open literature. This study examines ionic conductivity measurements based on the experimental technique in which a membrane directly contacts the electrodes. In the through-plane configuration of this technique, external resistances due to the interfacial region between the membrane and electrodes contribute significantly to the total measured resistance, particularly for thin membranes equilibrated with dilute salt solutions. A non-invasive approach to account for such external resistances based on performing the measurements with membranes having different thicknesses is presented. The total resistance of the electrochemical cell containing membranes with different thicknesses was measured via electrochemical impedance spectroscopy, and the results were extrapolated to zero thickness to determine the magnitude of the external resistances. The membrane ionic conductivity results obtained from this approach were compared to those obtained from measurements utilizing the in-plane configuration, in which external resistances were negligible, as well as measurements in which external resistances were eliminated by replacing the solution on the membrane surface with a highly conducting electrolyte solution. The salt concentration dependence of the ionic conductivity of homogeneous ion-exchange membranes is discussed within the Nernst-Einstein framework. |
| Databáze: | OpenAIRE |
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