Efficient removal of Sr2+ ions by a one-dimensional potassium phosphatoantimonate

Sr-90 is one of the most dangerous artificial radionuclides. Sr-90 generally exists in the form of Sr-90(2+) ions in radioactive waste liquids. The efficient removal of radioactive strontium from the complex aqueous environments remains a challenge due to high solubility and easy migration of Sr-90(2+) ions and the complex compositions of the radioactive waste liquids. Herein, a one-dimensional potassium phosphatoantimonate (1D-K2SbPO6) with the low cost presents the efficient removal of Sr2+ ions. It possesses the wide pH durability, excellent irradiation resistance and thermal stability. It exhibits the high adsorption capacity of qm = 175.90 mg/g and excellent selectivity for Sr2+ ions in the presence of competing Na+, Cs+, Mg2+ and Ca2+ ions and even in actual aqueous systems. The Sr2+ removal mechanism of K2SbPO6 is attributed to the ion exchange between Sr2+ and easily exchangeable K+ ions located between the [SbPO6](n)(2n-) chains in K2SbPO6. K2SbPO6 is the first example of antimonate(V)-based ion exchange materials with a one-dimensional structure for the Sr2+ capture. This work paves the way to the design and synthesis of new inorganic antimonite (V)-based ion exchange materials for radionuclides remediation.