Desalination of brackish water containing oil compound by capacitive deionization process Original Research Article

The feasibility of using capacitive deionization (CDI) was investigated for the desalination of brackish water containing oil compound. The reproducibility, salt removal efficiencies, and current efficiencies were examined at various cell potentials and cell configurations. For the CDI cell constructed with only porous carbon electrodes, the results showed stable and reproducible adsorption and desorption characteristics. But the current efficiency was low at 49.3% at the cell potential of 1.4 V. The low current efficiency was attributed to the dissolved salt present in the pore volume of the carbon electrode. To increase the current efficiency, desalination experiments were performed using a membrane capacitive deionization (MCDI) unit cell, which employed ion-exchange membranes as ion selective layers in a CDI cell. The current efficiency increased to 90.2% under the same experimental conditions. MCDI tests were conducted using an influent containing octane to elucidate the effect of oil compounds on desalination efficiency. The experimental results showed that the MCDI system could be successfully applied to the desalination of brackish water containing oil compounds.