Redox electrolyte enhances dual-anode FCDI (DA-FCDI) desalination of brackish and synchronously removal NOM

Natural brackish water bodies constitute complex mixtures. Accordingly, the production of high-quality drinking water from such sources necessitates the concurrent removal of salts and natural organic matter (NOM). A dual-anode circuit system (DA-FCDI) was developed by integrating electrochemical oxidation with flow-electrode capacitive deionization (FCDI). This dual-circuit configuration enables modulation of both desalination and electrochemical oxidation performances, while simultaneously regulating the charge and energy distribution between these two processes. At the same time, it was found that an increase in voltage difference between the internal and external circuits is beneficial for the degradation of organic matter. Furthermore, I − /I 3 − redox electrolytes were employed to expand the voltage window, thereby overcoming the voltage threshold limitation of the DA-FCDI system and enhancing its overall performance. When the applied voltage is 1.2 V - 1.8 V, ASRR and ATRR are 0.059 μmol cm −2  min −1 and 0.34 μg cm −2  min −1 , respectively, and the specific energy consumption is only 0.052 kWh/m 3 .Compared to other technologies, this FCDI and electrochemical oxidation integrated device significantly reduces the consumption of chemical agents and simplifies the process flow. More importantly, while improving economic efficiency, it endows the system with high adaptability and controllability to different water qualities. This study breaks through the bottleneck of traditional single technology that cannot regulate and remove salt and organic matter separately.