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Ion Separations Based on Spontaneously Arising Streaming Potentials in Rotating Isoporous Membranes
Chao Tang1, Andriy Yaroshchuk2,3, Merlin L Bruening1,4
1Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46656, USA.
Membranes
|June 23, 2022
Summary
Highly selective ion separations using charged membranes can be improved by controlling experimental conditions. Optimizing membrane rotation and feed composition significantly enhances lithium and potassium ion separation efficiency.
Area of Science:
- Membrane science
- Separation technology
- Electrochemistry
Background:
- Membrane-based ion separations offer an alternative to traditional methods.
- Previous studies showed charged isoporous membranes can separate Li+ and K+.
- Separation relies on streaming potentials and electromigration.
Purpose of the Study:
- To investigate factors influencing highly selective ion separations.
- To optimize conditions for enhanced Li+/K+ separation using charged membranes.
- To understand the role of concentration polarization in separation efficiency.
Main Methods:
- Utilizing pressure-driven flow through negatively charged isoporous membranes.
- Employing a rotating membrane system to control concentration polarization.
- Varying transmembrane pressure, ionic strength, feed ratio, and rotation rate.
Main Results:
- Achieved Li+/K+ selectivities up to 150 with optimized membrane rotation (1000 rpm).
- Selectivity decreased significantly at lower rotation rates (1.3 at 95 rpm).
- Increased ionic strength and feed ratio negatively impacted selectivity.
Conclusions:
- Careful control of experimental conditions, especially concentration polarization, is crucial for high selectivity.
- Membrane rotation is a key parameter for enhancing ion separation performance.
- This technique shows promise for efficient production of pure salts.
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