Several inorganic ion-exchange materials were synthesized hydrothermally and evaluated for separation of metals aiming to evaluate their suitability for radioisotope separations. In this work, we focused on the Zr/Y separation which is used in cyclotron production of PET isotope 89Zr from Yttrium targets and Sc/Ti for application as an ion-exchange support for 44Ti/44Sc generator. Current separation of 89Zr from Y involves adsorption of 89Zr on a hydroxamate resin (TrisKem Int., France) followed by its elution using oxalic acid solution. Oxalic acid is a somewhat undesirable eluent, as it needs to be removed before use of the final 89Zr product. Preliminary data indicated that poorly crystalline silicotitanate (pCST) is selective for Zr over Y in ammonium acetate buffer. In the experiment, a 1mL bed volume pCST resin was loaded with Zr and Y in 0.1M NaAc buffer at pH3: Yttrium was eluted while Zr retained. Zirconium was further eluted with 0.1M NH4OAc at pH 0.5. Elution fractions were analyzed by ICP-OES. The recovery of Y and Zr was 82.4% and 86.7%, respectively. Zirconium (IV) oxide prepared in-house by precipitation from ZrOCl2 solution was evaluated for the separation of Sc and Ti. Results of distribution coefficient measurements showed that the separation factor Kd Ti/Kd Sc is the highest for 0.1M 2,2-thiodiacetic acid at pH 3. A 0.1 ml bed volume ZrO2 based 44Sc/44Ti generator was prepared with 33μCi of 44Ti and eluted with this eluent. The fractions were analyzed using gamma spectroscopy. The 44Sc elution efficiency for the ZrO2 generator was 40.2% with a breakthrough of 0.36-1.4%. For comparison a generator based on anionic ion exchange resin (Rösch et al) was set up, and the elution efficiency was 69.0% with a breakthrough of &lt;0.5%. Further investigations optimizing the separation of Zr from Y and evaluation of 44Sc/44Ti generators are ongoing.

Inorganic ion-exchangers for radiochemical separations of Y/Zr and Sc/Ti

255th National Meeting (2018)

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