Novel ionic separation mechanisms in electrically driven membrane processes

I G Wenten; K Khoiruddin; Mohammad A Alkhadra; Huanhuan Tian; Martin Z Bazant

doi:10.1016/j.cis.2020.102269

Novel ionic separation mechanisms in electrically driven membrane processes

Adv Colloid Interface Sci. 2020 Oct:284:102269. doi: 10.1016/j.cis.2020.102269. Epub 2020 Sep 11.

Authors

I G Wenten¹, K Khoiruddin¹, Mohammad A Alkhadra², Huanhuan Tian², Martin Z Bazant³

Affiliations

¹ Department of Chemical Engineering, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132, Indonesia; Research Center for Nanosciences and Nanotechnology, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132, Indonesia.
² Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
³ Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA 02139, United States. Electronic address: bazant@mit.edu.

PMID: 32961418
DOI: 10.1016/j.cis.2020.102269

Abstract

Electromembrane processes including electrodialysis (ED) and related processes are usually limited by diffusion transport of ions from a bulk solution to ion exchange membranes. The diffusion limited current (DLC) occurs when the concentration at membrane surfaces vanishes and approaches zero. Increasing the applied potential difference above this point has no substantial effect on ion transport and causes operational problems such as low current efficiency, high energy consumption, and mineral scaling. However, it is evident from numerous studies that operating at overlimiting current (OLC) is possible and allows one to enhance the mass transfer of an electromembrane process. While OLC is sometimes possible by electrochemical means, such as water splitting or current induced membrane discharge, it has been found that exotic ion transport mechanisms, such as ion concentration polarization in micro/nanofluidic system, deionization shock waves, and ionic bridges, can provide novel electrokinetic means of achieving OLC. In this paper, these novel ionic separation mechanisms and their role in enhanced current transfer are reviewed in the context of emerging electromembrane processes, such as shock ED and electrodeionization (EDI).

Keywords: Desalination; Electrodialysis; Ion separation; Limiting current; Membrane.

Publication types

Review