Simultaneous removal and separate recovery of radioactive Cs+ and I− ions from wastewater using a reusable bifunctional composite, Ni@Pt/K2NiFe(CN)6

Radioactive Cs+ and I− ions are major components of nuclear wastewater, typically existing as counter ions. Due to their high water solubility and mobility, these ions can spread through contaminated water and soil into ecosystems, necessitating continuous removal and management. In this study, we synthesized a reusable bifunctional Ni@Pt/K2NiFe(CN)6 composite that can simultaneously remove radioactive Cs+ and I− ions and, for the first time, enable their separate recovery in aqueous solutions. In this material, K2NiFe(CN)6 acted as an electrochemically switched ion exchanger, controlling the adsorption/desorption of Cs+, while Pt enabled the spontaneous adsorption and electrochemical desorption of I−, and the magnetic Ni core allowed for efficient adsorbent recovery. The adsorption isotherms of both Cs+ and I− were best fitted using the Langmuir model, and the corresponding adsorption capacities were comparable to those of conventional adsorbents used for the separate removal of Cs+ and I−. Furthermore, the composite demonstrated stability over 100 sorption cycles, maintaining high recovery efficiencies of 97.9 % for Cs+ and 99.7 % for I−, thereby proving its reusability. Thus, the developed composite holds great promise for radioactive wastewater treatment and environmental restoration.