Highly Selective Capacitive Deionization of Copper Ions in FeS2@N, S co-doped Carbon Electrode from Wastewater

Abstract Capacitive deionization (CDI) as a promising water treatment technique aroused great concern for selective electrosorption of heavy metal ions from complex wastewater. Here, for the first time, we developed FeS2@N, S co-doped carbon (FeS2@NSC) composites as a novel electrode material for high-efficiency selective electrosorption of Cu2+ ion under various cations coexistence system. On account of the synergistic effect of electric double layers and pseudocapacitance of FeS2@NSC electrode, the superior electrosorption performance of 508.5 mg∙g−1 and high coefficient of selectivity (Cu2+/Na+) of 71.6 at molar ratio of 1:10 for Cu2+ ion were achieved at 1.0 V. Significantly, the FeS2@NSC electrode had obvious Cu2+ ion selective electrosorption behavior in mixed ions environment including Cu2+, Pb2+, Cd2+, Zn2+, Co2+ and Mn2+ ions. Finally, the ex-situ XRD and XPS characterization demonstrated that the highly selective electrosorption of Cu2+ ion in FeS2@NSC was dominated by the Faradic redox reaction of the Fe2+/Fe3+ and Cu2+/Cu+ couples. The selective electrosorption performance of FeS2@NSC electrode was also confirmed by treatment of real copper-containing electroplating wastewater.