Clean water via Membrane Capacitive Deionisation

- Capacitive deionization (CDI) has been proposed as an energy efficient route to desalinate water, although the practical performance of many devices reported to date has been well below the theoretical expectations, in terms of both absolute salt removal and the rate of that removal.
- We will use detailed electrochemical approaches to understand, and therefore optimize, the electrode processes occurring within the CDI cell. Initially activated carbons will be used as the model electrodes, to enable comparison with existing literature. The plan would be to move to more advanced materials subsequently, including electrodes formed from graphene and graphene-MoS2 composites. The latter are of interest because of other work showing that MoS2 has some ion-selective behavior, indicating that MoS2 could function simultaneously as an electrode and membrane material within the CDI cell. One barrier to the evaluation of performance of CDI cells is the difficulty in monitoring cell composition (ie electrolyte removal). Conductivity methods are often used, but the cells are remote from the CDI electrodes, meaning there is a spatial averaging and time delay with regard to the measurement of water salinity. This problem will be addressed by incorporating inert Pt electrodes within the CDI cell to permit in situ monitoring of solution conductivity.
- We are unaware of any purely electrochemical approaches to CDI being pursued within the current UK research portfolio. The areas of electrochemical technology, energy storage and water treatment all lie firmly within the EPSRC remit.