Copper hexacyanoferrate/carbon nanostructure hybrids: electrochemically switched ion-exchange electrodes for the sustainable removal of cesium from water

Herein, we report the design and fabrication of carbon supported copper hexacyanoferrate (CuHCF) based nanohybrids as potential electrode materials for electroadsorptive removal of Cs+ from aqueous solution. Specifically, we present a hydrothermal approach for the synthesis of cubic shaped CuHCF decorated carbon nanostructures (CuHCF/CNS) viz. multi-walled carbon nanotubes (CuHCF/f-CNT), graphene oxide (CuHCF/GO) and graphitic carbon nitride (CuHCF/g-C3N4). The crafted CuHCF/CNS materials exhibit an excellent ability for electroadsorptive removal of Cs+ from its aqueous solutions, due to enhanced charge transport and high surface area offered by the CNS support to the selectively ion specific CuHCF functional units in the CuHCF/CNS hybrid. Among the CuHCF/CNS hybrids crafted for the present work, the cesium uptake capacity of CuHCF/f-CNT hybrid is highest, almost 2–3-fold higher than that reported for the various state-of-art materials. The impact of electrolyte concentration, Cs+ ion concentration, and the regeneration and selectivity for Cs+ ions over K+ over the CuHCF/CNS hybrids is also presented. We opine that the results presented herein clearly reveal the fundamental requirements and the potential advantages of combining electro-adsorption and ion exchange strategy for selective and efficient removal of 137Cs+ from radioactive liquid wastes.