Selective removal of chromium and chloride by flow electrode capacitive deionization (FCDI) with carrier-facilitated ion exchange membrane

Abstract

In confronting the widespread challenge of chromium (Cr(VI)) pollution in industrial effluents, this study pioneers the integration of flow electrode capacitive deionization (FCDI) with carrier-facilitated ion exchange membrane (IEM) for selective heavy metal removal, which offers a marked enhancement in selectivity and energy efficiency over conventional treatments. Our comprehensive study demonstrates that the synergistic system significantly optimizes Cr(VI) elimination from low-concentration effluents, achieving an unprecedented selectivity coefficient of 20.6 under optimal operational parameters. The system performance is critically influenced by the system’s operational parameters, including current density and ion concentration, with lower current densities favoring reduced energy consumption and higher selectivity without compromising removal efficiency. The pronounced permeability coefficient suggested that the Cr(VI) transport in the membrane occurs via continuous pathways, rather than fixed-site jumping mechanism. Furthermore, this innovative configuration exhibits remarkable adaptability to fluctuating Cr(VI) and Cl− concentrations, ensuring consistent high-performance removal. Comparative analysis with traditional electrodialysis (ED) systems illustrates the potential of our proposed method in delivering significant energy savings and operational benefits. This investigation not only broadens the horizon of membrane separation technology but also underscores the potential of FCDI-based processes in fostering the development of more sustainable water treatment and hazardous material remediation strategies.