Adsorption mechanism of radioactive cesium by Prussian blue

Since the accident at the Fukushima Daiichi power plant, Prussian blue (PB) has attracted increasing attention as a material for use in decontaminating the environment. We have focused the fundamental mechanism of specific Cs⁺ adsorption into PB in order to develop high-performance PB-based Cs⁺ adsorbents. The ability of PB to adsorb Cs varies considerably according to its origin such as what synthesis method was used, and under what conditions the PB was prepared. It has been commonly accepted that the exclusive abilities of PB to adsorb hydrated Cs⁺ ions are caused by regular lattice spaces surrounded by cyanido-bridged metals. Cs⁺ ions are trapped by simple physical adsorption in the regular lattice spaces of PB. Cs⁺ ions are exclusively trapped by chemical adsorption via the hydrophilic lattice defect sites with proton-exchange from the coordination water. Prussian blue are believed to hold great promise for the clean-up of ¹3^7Cs contaminated water around nuclear facilities and/or after nuclear accidents