Poly(dialydimethylammonium chloride)-functionalized graphene composites with copper hexacyanoferrate for enhanced cesium removal via capacitive deionization

Cesium ions (Cs⁺) present in liquid waste is a critical concern in nuclear environments, and capacitive deionization (CDI) has emerged as a sustainable approach to remove these ions. This study presents the synthesis of copper hexacyanoferrate (CuHCF) embedded in graphene layers to overcome the inherent conductivity limitations of pristine CuHCF. The CuHCF/graphene composites exhibit enhanced electrochemical performance with a specific capacity of 189 F g⁻¹ at 2 mV s⁻¹, which is better than that of CuHCF electrodes (166 F g⁻¹). Including graphene significantly improves ion transport, rate capability, and energy density, achieving a deionization capacity of 267 mg g⁻¹ for Cs⁺ ions at 1.4 V in a CDI system. The developed material demonstrated high selectivity for Cs⁺ ions over the competing Sr²⁺ and Na⁺ ions. These findings demonstrate the potential of CuHCF/graphene composites as efficient electrode materials for environmental remediation and wastewater treatment. • Developed a graphene-embedded copper hexacyanoferrate composite to overcome the intrinsic conductivity limitations of pristine CuHCF. • CuHCF/graphene composites exhibit enhanced electrochemical performance. • Graphene significantly improves ion transport, rate capability, and energy density. • Proposed material has high selectivity for Cs⁺ over competing Sr²⁺ and Na⁺ ions.