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Updated: Dec 12, 2025

Merging Ion Concentration Polarization between Juxtaposed Ion Exchange Membranes to Block the Propagation of the Polarization Zone
Published on: February 23, 2017
Flow through negatively charged, nanoporous membranes separates Li+ and K+ due to induced electromigration
Chao Tang1, Andriy Yaroshchuk, Merlin L Bruening
1Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46656, USA. mbruenin@nd.edu.
Abstract:
Flow through negatively charged nanopores separates Li+ and K+ with selectivities of up to 70 and Li+ passages from 20% to above 100%. Remarkably, both the Li+/K+ selectivity and Li+ passage initially increase with flow rate, breaking the permeability/selectivity trade-off. Modelling demonstrates that flow through the membranes creates electric fields that retard transport of cations. Selectivity increases with flow rate because the K+ electromigration velocity exceeds its convective velocity, but for Li+ electromigration is weaker than convection. Modelling also shows the importance of controlling concentration polarization. With further work, related separations might provide highly pure Li salts for battery manufacturing.
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