Fabrication of self-assembled Prussian blue graphene hydrogel for highly selective removal of radioactive cesium in water: Adsorption study

This paper reports a simple and cost-effective method for fabrication of a 3D porous and redox-active Prussian blue-graphene (PBG) hydrogel using ferrous ions to reduce graphene oxide sheets. The hydrogel was obtained via sonication for 5 min only at a low temperature of 40 °C without the need of purification or centrifugation. The hydrogel exhibited high selectivity for cesium ions due to the cubic framework of iron centers bound by cyanide bridges, which allows for intercalation of additional cations. The hydrogel's centered-cubic phase of Prussian blue was confirmed through XRD, and its existence was demonstrated through FTIR and XPS. The BET surface area measurements revealed that the composite's adsorptive surface area increased as compared to magnetic PBGO. Furthermore, the hydrogel's adsorption potential for cesium ions increased to 4.67 mmol/g (621.11 mg/g) compared to the previous work, fitting well with the Langmuir isotherm and the pseudo-second order kinetic model. Moreover the optimal values for temperature and pH for cesium ions removal were found to be 30 °C and neutral, respectively.