Novel Reuse Strategy in Flow-Electrode Capacitive\nDeionization with Switch Cycle Operation To Enhance Desalination Performance

Abstract

Flow-electrode\ncapacitive deionization (FCDI) is a promising electrochemical\ndesalination system because of its superior desalination capacity\nduring a continuously operating process. However, FCDI suffers from\na lack of an effective reuse step for charged flow-electrodes for\nconducting continuous desalination despite several approaches such\nas mixing charged flow-electrodes [short-circuit cycle (SCC) operation]\nand applying a reverse voltage. Herein, we report a novel strategy\ntermed switch cycle operation in which the charged flow-electrodes\nfrom positively and negatively biased electrode channels are swapped\nand supplied to oppositely biased electrode channels for the next\nsequential desalination step. The major results include switch cycle\noperation achieving the effective reuse of charged flow-electrodes\nfor the next desalination step. The desalination performance, expressed\nin terms of salt removal efficiency and system current in FCDI, significantly\nimproved by approximately 1.7 times compared with that of the SCC.\nThis enhanced performance is attributed to the release of ions from\nthe charged flow-electrodes that cause additional ion flux to achieve\ncharge neutrality during the sequential desalination steps.