Highly efficient and selective removal of Sr2+ from aqueous solutions using ammoniated zirconium phosphate

Radioactive wastewater contains high concentrations of 90 Sr (strontium-90), which poses a serious threat to human health and ecosystems. Layered ammoniated zirconium phosphate (A-ZrP) was synthesized herein using a one-pot hydrothermal method for the adsorptive removal of Sr 2+ . ZrP was ammoniated between its structured layers to increase interlayer spacing and facilitate the access of Sr 2+ ions to adsorption sites and realize adequate ion exchange. A-ZrP achieved a faster equilibration time (120–240 min) compared with that of other ZrPs (250–500 min). A-ZrP exhibited excellent Sr 2+ uptake selectivity ( K d = 5.3 × 10 5 mL g −1 ) and maximum adsorption capacity ( q m = 341 mg g −1 ) at a pH of 7. Moreover, A-ZrP displayed high selectivity in various contaminated solutions, with a high K d value of 681 mL g −1 , even in artificial seawater. The adsorption mechanism was found to involve ion exchange between NH 4 + and Sr 2+ , primarily because of electrostatic interactions and chemical hardness. These results highlight the potential of A-ZrP as an efficient adsorbent for the selective removal of Sr 2+ ions from wastewater. • Ammonium-intercalated zirconium phosphate (A-ZrP) had a wide interlayer spacing. • A-ZrP exhibited a high capacity for adsorbing Sr 2+ from water ( q m = 341 mg g −1 ). • A-ZrP rapidly removed nearly 93% of Sr 2+ in 30 min (equilibration time ≅ 120 min). • A-ZrP showed excellent Sr 2+ uptake selectivity ( K d ≅ 5.3 × 10 5 mL g −1 at a pH of 7). • A-ZrP demonstrated potential sequestration of Sr 2+ from various types of waters.