Engineering surface microenvironment in La-doped Sb₂O₅ for highly efficient separation of strontium from yttrium in strongly acidic media

The selective separation of 90 Sr from its daughter 90 Y is crucial for obtaining carrier-free 90 Y. Herein, we demonstrate a La doping strategy to modulate the microstructure and surface properties of Sb 2 O 5 to enhance the separation performance of Sr/Y. Batch studies show that 7%-LaSb exhibits significantly enhanced separation performance compared to Sb 2 O₅ across a broad range of HNO₃ concentrations, achieving a remarkable separation factor of 3449 for Sr 2+ in 0.3 M HNO₃. The equilibrium isotherms align with the Langmuir model, yielding a maximum Sr 2+ adsorption capacity of 40.82 mg/g for 7%-LaSb. Column experiments further validate the practical efficacy of Sr 2+ separation from Y 3+ -containing streams. Mechanistic studies indicate that the high separation performance is attributed to the changes in surface microenvironment induced by La doping: (i) defect-rich porous pathways for Sr 2+ ion access, (ii) a more electronegative surface for enhanced Sr 2+ attraction, and (iii) abundant active Sb-OH sites for specific ion-exchange. This work provides a promising new adsorbent for the separation of Sr/Y in strong acid environments.