Removal of Fe Impurity Ions from a Spent Vanadium Electrolyte Using Capacitive Deionization Based on Resin/Activated Carbon Composite Electrodes

Capacitive deionization (CDI) based on LSC-957 resin/carbon composite electrodes was used to remove Fe impurity ions from a spent vanadium electrolyte, which enabled simple and efficient regeneration of the electrolyte. The experiments conducted in this study demonstrated that 3:1 was the optimal mass ratio of LSC-957 resin to activated carbon for the preparation of the composite electrodes, and the optimal operating voltage and operating time were 0.9 V and 6 h, respectively. After five stages of CDI tandem treatment, the adsorption rate of Fe impurity ions was 86.84% and the loss rate of V was only 3.8%. The energy efficiency of the regenerated electrolyte was 84.49%, and its performance was significantly improved compared to the spent vanadium electrolyte. The adsorption process of composite electrodes was analyzed by kinetic and isothermal models' fit, SEM-EDS, and FTIR. This work has provided an effective and novel method for removing impurity ions from a spent electrolyte.