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Updated: May 29, 2026

Merging Ion Concentration Polarization between Juxtaposed Ion Exchange Membranes to Block the Propagation of the Polarization Zone
Published on: February 23, 2017
Bipolar electrode depletion: membraneless filtration of charged species using an electrogenerated electric field
Eoin Sheridan1, Kyle N Knust, Richard M Crooks
1Department of Chemistry and Biochemistry, Center for Electrochemistry, The University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712-0165, USA.
Abstract:
We report a method for removing ions from aqueous solutions without the use of a membrane. The approach, which we call bipolar electrode depletion (BED), is based on the formation of an asymmetric electric field profile in a microchannel containing a bipolar electrode (BPE). The asymmetric field arises from local increases in conductivity caused by faradaic reactions at the BPE. We show how the asymmetric field can be used to deplete anions from a microchannel via a combination of electrophoresis and electroosmosis. We also apply this approach to filter an anionic species from a mixture of charged and neutral species being transported through a microchannel via electroosmosis. This technique could be utilized for desalination or filtration of any species possessing a net charge (e.g. heavy-metals, bacteria, proteins, or functionalized-nanoparticles).
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