A theoretical understanding of ionic current through a nanochannel driven by a viscosity gradient
Amer Alizadeh1, Hirofumi Daiguji2, Anne M Benneker1
1Department of Chemical and Petroleum Engineering, Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada.
Journal of Colloid and Interface Science
|August 25, 2022
Summary
A viscosity gradient can drive electrical current in nanochannels, a phenomenon termed visco-migration. This study models visco-migration using the Maxwell-Stefan equation, revealing solvent ideality and bulk solution properties significantly impact ionic drift.
Area of Science:
- Physical Chemistry
- Nanotechnology
- Electrokinetics
Background:
- Ionic current is typically driven by thermodynamic forces like temperature, electrical potential, or concentration gradients.
- Recent work demonstrated viscosity gradients can induce electrical current in charged nanochannels, a phenomenon termed visco-migration.
Purpose of the Study:
- To theoretically describe the physical mechanisms of visco-migration using a 1D model.
- To establish a relationship between solvent flux and driving forces in nanochannels.
Main Methods:
- Developed a 1D model based on the Maxwell-Stefan equation.
- Analyzed the impact of solvent ideality, ionic strength, and pH on ionic drift.
- Investigated the role of diffusion gradients in driving ionic species.
Main Results:
- The model shows ionic current is influenced by solvent ideality, aligning with experimental data for both ideal and non-ideal solvents.
- Bulk solution properties, such as ionic strength and pH, significantly affect ion drift.
- Diffusion gradients contribute substantially to ionic species drift, even with small concentration gradients.
Conclusions:
- The developed model accurately describes visco-migration and its dependence on solution properties.
- Findings suggest potential novel applications for ion drift in diffusion gradients induced by viscosity differences.
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