Simultaneous removal of cesium and iodate using prussian blue functionalized CoCr layered double hydroxide (PB-LDH)

Radioactive cesium and iodine have become an emerging issue because these radionuclides have high radiotoxicity and solubility, and they can easily transport to the surrounding environment. Prussian blue, known as metal hexacyanoferrate compound, has a cubic face-centered structure and similar ionic size to Cs+, known to be used for Cs+ removal. In addition, layered double hydroxides (LDHs) have anion exchange properties and become the promising sorbents of iodine. In this study, based on the advantages of both Prussian blue (PB) and layered double hydroxide (LDH), Prussian blue functionalized layered double hydroxide (PB-LDH) was synthesized to concurrently remove both Cs+ and IO3− from radioactive solutions. During the synthesis of PB-LDH, Fe(CN)64− does not intercalate into the LDH structure, but aggregates on the LDH surface according to electrostatic force and ion-specific effects and forms the PB on the surface of LDH. The synthesized PB-LDH simultaneously removed 32 mg/g of Cs+ and 91 mg/g of IO3− from the mixed waste solutions. The main removal mechanism of Cs+ was redox coupled alkali metal ion transport to form Cs4Co4FeⅡ3(CN)18 species at the surface of PB-LDH. However, IO3− was mainly removed by ion exchange with intercalated Cl− in addition to the redox effect of Co ions.