Synthesis of α-Ti(HPO4)2 · H2O for the Separation of Radionuclides
Using Barium and Lanthanum as Analogues for Radium and Actinium
J.W. van den Berg (TU Delft - Applied Sciences)
Antonia G. Denkova – Mentor (TU Delft - RST/Applied Radiation & Isotopes)
Robin M. de Kruijff – Graduation committee member (TU Delft - RST/Applied Radiation & Isotopes)
Erik Kelder – Graduation committee member (TU Delft - RST/Storage of Electrochemical Energy)
Lars Bannenberg – Graduation committee member (TU Delft - RID/TS/Instrumenten groep)
K. Djanashvili – Graduation committee member (TU Delft - BT/Biocatalysis)
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Abstract
The medical interest in targeted alpha therapy (TAT) has increased the demand for actinium-225 (225Ac), a promising isotope for cancer treatment. However, the production falls short. One potential route is the generation of 225Ac via proton irradiation of radium-226 (226Ra), introducing the challenge of separating these radionuclides. In this study, lanthanum and barium were used as chemical analogues for actinium and radium, respectively. This study investigates the production and characterisation of α-titanium phosphate (α-Ti(HPO4)2 · H2O, α-TiP) and its feasibility for the separation of lanthanum and barium using ion exchange.
Three synthesis methods were used with different titanium precursors: TiO2, Ti powder and TiOSO4. The resulting α-TiP samples were characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), confirming phase purity but showing morphological differences.
The ion exchange behaviour of α-TiP was found to be closely linked to morphology and exchange site accessibility. Batch adsorption experiments demonstrated that α-TiP exhibits strong selectivity for trivalent lanthanum (La3+) over divalent barium (Ba2+) ions at acidic pH and relevant concentration ([La3+] = 2.5 μM and [Ba2+] = 1.0 mM).
The results support the potential of α-TiP as a viable material for lanthanum–barium separation. However, further studies are required to confirm radiation stability, reversibility of ion uptake and performance in column-based separation systems. Additionally, experiments should validate whether similar separation behaviour will be achieved for actinium and radium separation.