Highly selective separation of strontium(II)/yttrium(III) on tetragonal zirconium phosphate by pH-controlled adsorption behavior

Efficient separation of Sr 2+ and Y 3+ is crucial for 90 Sr/ 90 Y radionuclide generators. Here, three-dimensional tetragonal zirconium phosphate (τ-ZrP) was synthesized as an inorganic ion exchanger. The material exhibits exceptional Y 3+ selectivity under acidic conditions. Kinetic studies showed rapid Y 3+ uptake, reaching equilibrium within 1 h. The adsorption process followed the pseudo-second-order model. At pH 1, the maximum Y 3+ removal reached 99.4%, with a K d of 1.76 × 10 5  mL g −1 . In contrast, Sr 2+ adsorption was completely suppressed. High Y 3+ uptake persisted even at an extreme Sr 2+ /Y 3+ molar ratio of 5000:1. Furthermore, τ-ZrP retained over 90% removal and recovery after five cycles in strong acid. Spectroscopic analyses confirmed that Y 3+ coordinates with phosphate groups via proton exchange. DFT calculations revealed that the Y 3+ adsorption energy is 1.82 eV lower than that of Sr 2+ . This energy difference markedly exceeds those of α-ZrP (0.68 eV) and γ-ZrP (1.31 eV). Overall, τ-ZrP represents a promising candidate for high-purity 90 Y production.