Case 12238

Desalination with Electric Field and Flow Discharge of Ions


Water desalination, Capacitive deionization, Permeating flow discharge (PFD)


Production of potable water from brackish water, generation of potable water using small, portable units during natural disasters and other emergency situations, deionization of radioactive elements in water, and semiconductor fabrication

  • Prohibitive costs associated with current desalination technologies
  • Low water recovery ratio of conventional capacitive deionization leading to unacceptably low system throughput


This invention introduces a new capacitive deionization process with permeating flow discharge (PFD). The process involves the flow of saline water through a pair of high surface area, porous electrodes across which a small voltage is applied. During the flow the ions in the saline water move towards respective electrodes and consequently the water flowing out of the system is de-ionized. In the novel configuration, the waste water is permeated through porous electrodes rather than allowing the waste water to flow between the electrodes, as in the conventional axial flow discharge process. The new permeating flow discharge process is able to completely clear the electrode surfaces of all ions in a much smaller time interval, which increases the water recovery ratio and consequently the net throughput by 15-20%.

  • Enhancement of the water recovery ratio and throughput of the capacitive desalination process
  • Low energy consumption and no high pressure pumps required
  • Suitability for high salinity water desalination
  • Capability to package into small, portable desalination chambers powered by solar energy or batteries

  • Professor Nam Pyo Suh(Department of Mechanical Engineering, MIT)
  • Professor Sang-Gook Kim(Department of Mechanical Engineering, MIT)
  • Dr. Taesik Lee (Department of Mechanical Engineering, MIT)
  • Dr. Gyunyoung Heo (Department of Mechanical Engineering, MIT)
  • Ishan Barman (Department of Mechanical Engineering, MIT)

Intellectual Property:

US patent filed on December 19, 2007


Barman, I., Lee, T., Heo, G., Suh, N.P., “Capacitive deionization process with decoupled charging and discharging flow schemes”, Proceedings of the Fifth International Conference on Axiomatic Design, Campus de Caparica, Lisbon, Portugal, pp. 185-192, 25-27 March, 2009.

Barman, I., Lee, T., Kim, S.-K., Suh, N.P., “Towards a low cost desalination process: Capacitive deionization with permeating flow discharge”, 2007 MIT Manufacturing Summit, September 27, 2007 (poster presentation).

Last revised:November 8, 2010

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