Electrochemical Ion Pump

Electrochemical ion pumping (EIP) is a novel system design that aims to combine the flexibility of electrosorption cells with the scalability of electrodialysis stacks. EIP stacks consists of two terminal electrodes and alternating array of flow channels, separated by either an ion exchange membrane that blocks ions of a specific sign, or a porous electrode used for electrosorption, usually termed shuttling electrodes (of either cations or anions). During the charging step (denoted by solid lines and arrows), ions leave the feed stream to be stored by the electrode. Next, during the discharge step (denoted by dashed lines and arrows), the ions leave the electrodes and are released into the receiving stream.

The unique design allows for short charging times, which can be leveraged to achieve exceptional selectivities, as well as pseudo-continuous operation (considering the flow). As this is a new design, only a handful of studies have been conducted, focusing on salt desalination. Therefore, in our lab, we plan to study ion-ion selective separations, relying on simple electrode materials. To that end, we will combine numerical study, bench-scale experiments, and fluorescence microscopy.

Further reading:

• The first paper presenting the design: Xu et al., Nat. Water, 2024, link: https://doi.org/10.1038/s44221-024-00312-8
• A paper presenting one of the first models describing the system: Liu et al., Nat. Water, 2025, link: https://doi.org/10.1038/s44221-025-00480-1