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Merging Ion Concentration Polarization between Juxtaposed Ion Exchange Membranes to Block the Propagation of the Polarization Zone
Published on: February 23, 2017
Electro-convective versus electroosmotic instability in concentration polarization.
Isaak Rubinstein1, Boris Zaltzman
1DSEEP, Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Sede-Boqer Campus, 84990, Israel. robinst@bgu.ac.il
Advances in Colloid and Interface Science
|June 15, 2007
Summary
Electro-convection drives mixing in strong electrolytes near charged membranes, enhancing conductivity. This mixing, driven by electroosmotic slip, is crucial for processes like electrodialysis.
Area of Science:
- Electrochemistry
- Fluid Dynamics
- Physical Chemistry
Background:
- Electro-convection is a key mixing mechanism in electrolyte diffusion layers adjacent to charged solids.
- Two types exist: bulk electro-convection and electro-convection induced by electroosmotic slip.
- The latter is increasingly recognized as the primary source of mixing, causing over-limiting conductance.
Purpose of the Study:
- To review electro-convection as a mixing mechanism in strong electrolytes.
- To differentiate between bulk electro-convection and electro-convection induced by electroosmotic slip.
- To analyze the hydrodynamic instability leading to electro-convection near charged interfaces.
Main Methods:
- Review of existing literature on electro-convection.
- Linear stability analysis of electric conduction through charged interfaces.
- Comparison of full electro-convective and electroosmotic formulations.
Main Results:
- Electro-convection induced by electroosmotic slip is identified as the main contributor to diffusion layer mixing.
- Hydrodynamic instability of electric conduction initiates electro-convection near planar charged interfaces.
- Analysis of short- and long-wave instabilities and wave number selection principles.
Conclusions:
- Electro-convection, particularly that driven by electroosmotic slip, is vital for understanding mixing and over-limiting conductance in systems like electrodialysis.
- The study provides insights into the onset and characteristics of electro-convective instabilities.
- Further research into these instabilities can optimize electrochemical processes.
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