Comparison of constant voltage (CV) and constant current (CC) operation in the membrane capacitive deionisation process

In this study, desalination characteristics were systematically compared and analysed during operation of the membrane capacitive deionisation (MCDI) process in constant current (CC) and constant voltage (CV) modes. Operational characteristics in the MCDI process such as the change in effluent concentrations, the number of adsorbed ions, charge efficiencies and energy consumption were compared based on the power supply mode. When the cell potential was not varied, more ions were adsorbed in CV mode than in CC mode. However, it was determined that desorption proceeded rapidly when performing adsorption in CC mode. Regarding the charge efficiency, the process in CV mode exhibited a higher efficiency than in CC mode. In particular, the charge efficiency decreased beyond a cell potential of 0.8V due to electrode reactions. In contrast, the energy consumption was greatly reduced when operating the MCDI process in CC mode compared with when operating the MCDI process in CV mode.