Effect of activated carbon electrode material characteristics on hardness control performance of membrane capacitive deionization

Capacitive deionization (CDI) is an electrochemical-based water treatment technology that has attracted attention as an effective hardness-control process. However, few systematic studies have reported the criteria for the selection of suitable electrode materials for membrane capacitive deionization (MCDI) to control hardness. In this study, the effect of electrode material characteristics on the MCDI performance for hardness control was quantitatively analyzed. The results showed that the deionization capacity and the deionization rate were affected by the specific capacitance and BET-specific surface area of the activated carbon electrode. In addition, the deionization rate also showed significant relationship with the BET specific surface area. Furthermore, it was observed that the deionization capacity and the deionization rate have a highly significant relationship with the BET specific surface area divided by the wettability performance expressed as the minimum wetting rate (MWR). These findings highlighted that the electrode material should have a large surface area and good wettability to increase the deionization capacity and the deionization rate of MCDI for hardness control. The results of this study are expected to provide effective criteria for selecting MCDI electrode materials aiming hardness control.