Flow capacitive deionization (FCDI) technology holds significant promise for cost-effective and energy-efficient desalination; however, its practical application is hindered by limited electrode stability and desalination performance. In this study, we propose a novel composite strategy that combines chemical surface modification with surfactant-assisted dispersion to enhance electrode performance in FCDI systems. We observed that the dispersion stability and capacitance of the flow electrodes were significantly improved after oxidation (AC-O) or amination (AC-N) of activated carbon (AC). To further investigate the underlying ion adsorption mechanisms, we performed Density Functional Theory (DFT) simulations. The simulations revealed that oxidative modification (AC-O) enhances chloride ion adsorption through stronger electrostatic and van der Waals interactions, while amination (AC-N) is more effective for sodium ion adsorption. Subsequently, surfactants (sodium dodecyl sulfate, SDS; cetyltrimethylammonium bromide, CTAB) were used to prepare stable and high-performance flow electrodes. Electrochemical characterization and desalination tests in a 1000 mg·L−1 saline solution demonstrated that the AC-O/SDS composite exhibited excellent dispersion stability (>7 d) and significantly enhanced conductivity and specific capacitance, increasing by factors of 2.48 and 2.50, respectively, compared to unmodified AC. This optimized electrode achieved a desalination efficiency of 74.37% and a desalination rate of 6.2542 mg·L−1·min−1, outperforming the unmodified electrode by a factor of 5.72. Our findings provide a robust, sustainable approach for fabricating advanced flow electrodes and offer valuable insights into electrode structure optimization, opening new possibilities for the application of FCDI technology in water treatment and material sciences.
Qiao et al. (2025) studied this question.