Desalination performance of silver/activated carbon hybrid capacitive deionization under constant-current operation

초록

Capacitive deionization (CDI) is a promising desalination technology but is often limited by the low ion removal capacity of carbon-based electrodes. In this study, a hybrid capacitive deionization (HCDI) system employing an asymmetric silver/activated carbon (Ag/AC) electrode configuration was investigated under constant-current operation and compared with a conventional membrane capacitive deionization (MCDI) system. Desalination performance was evaluated using CDI Ragone plot analysis, while galvanostatic charge-discharge measurements were used to examine the potential evolution of individual electrodes. The results show that the Faradaic Ag/AgCl reaction stabilizes the cell voltage and expands the usable potential window of the activated carbon electrode. As a result, the HCDI system consistently outperformed MCDI, achieving a maximum salt adsorption capacity of 36.5 mg g-1 in a 10 mM NaCl solution, more than twice that of MCDI (17.0 mg g-1), along with a faster ion removal rate. These findings demonstrate that integrating Faradaic electrodes effectively overcomes the intrinsic capacity limitations of conventional CDI systems.

키워드