Electrosorption Cell

Electrosorption cells, also known as capacitive deionization (CDI), consist of two porous electrodes, separated by a non-conductive separator. Upon charging, ions are stored by the electrodes, resulting in dilution of the stream. As soon as the electrodes are fully charged, a discharging step is performed to regenerate them, resulting in a concentrated stream.

Electrosorption cells have great potential to perform a variety of ion-ion selective separations in a flexible and tunable manner by varying properties such as electrode materials, charging voltage window, cycle timing, and flow rates. For example, using a very similar cell, both perfect calcium selectivity and perfect sodium selectivity can be achieved. Moreover, local pH variations develop during the charging process, enabling the removal of species with pH-dependent charge, such as boron, phosphate, and ammonia. In our lab, we utilize simple electrode materials to achieve a variety of selective separations. To that end, we combine numerical models, bench-scale experiments, and fluorescence microscopy.

Further reading:

• Monovalent selective removal of sodium over calcium:
  • Guyes et al., npj Clean Water, 2021, link: https://doi.org/10.1038/s41545-021-00109-2
  • Sahray et al., Water Res., 2023, link: https://doi.org/10.1016/j.watres.2023.120684
• Divalent selective removal of calcium over sodium: Uwayid et al., Water Res., 2022, link: https://doi.org/10.1016/j.watres.2021.117959
• Ion-exchange between sodium and calcium: Mathur et al., J. Mater. Chem. A, 2025, link: https://doi.org/10.1039/d5ta05182g
• Chemical-free boron removal:
  • Shocron et al., PNAS, 2021, link: https://doi.org/10.1073/pnas.2108240118
  • Shocron et al., Chem. Eng. J., 2023, link: https://doi.org/10.1016/j.cej.2023.142722