First Potassium Fluoroaluminate Ionic Exchanger for Rapid and Selective Removal of Sr 2+ with High Capacity

Sr, as a typical artificial radionuclide, poses a serious threat to human health and the ecological environment. The selective removal of this radionuclide from industrial nuclear waste is crucial for our environment. Here we report a novel potassium fluoroaluminate, K [(AlF )H O], which was synthesized by a simple low-temperature one-step method. It adopts a 1D AlF -chain structure, which consists of exchangeable potassium ions in between the infinite chains of octahedral Al centers. As a remarkable inorganic ionic exchanger, K [(AlF )H O] has a high chemical stability (resistance of pH=~3-12) and thermal stability (≥~300 °C). It possesses an excellent adsorption selectivity (K =~6.1×10 mL ⋅ g ) and a maximum adsorption capacity of q =~120.32 mg ⋅ g for Sr . Importantly, it still keep a very good selectivity for Sr ions even in the presence of competing Na , Mg and Ca aqueous solutions. K [(AlF )H O] is the first example of fluoroaluminate ionic exchange materials that can capture Sr . This result opens up a new way to design and synthesize inorganic ionic exchangers for the selective removal of Sr ions from radioactive waste water.