The application of poorly crystalline silicotitanate in production of 225Ac

Jonathan Fitzsimmons,Alyson Abraham,Dmitri Medvedev,Cathy S Cutler,Ali Younes,Demetra Catalano

doi:10.1038/s41598-019-48021-7

Jonathan Fitzsimmons, Alyson Abraham + Show 4 more

Open Access

https://doi.org/10.1038/s41598-019-48021-7

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Abstract

Actinium-225 (225Ac) can be produced from a Thorium-229/Radium-225 (229Th/225Ra) generator, from high/low energy proton irradiated natural Thorium or Radium-226 target. Titanium based ion exchanger were evaluated for purification of 225Ac. Poorly crystalline silicotitanate (PCST) ion exchanger had high selectivity for Ba, Ag and Th. 225Ac was received with trace amounts of 227Ac, 227Th and 223Ra, and the solution was used to evaluate the retention of the isotopes on PCST ion exchanger. Over 90% of the 225Ac was recovered from PCST, and the radiopurity was >99% (calculated based on 225Ac, 227Th, and 223Ra). The capacity of the PCST inorganic ion exchange for Barium and 232Th was determined to be 24.19 mg/mL for Barium and 5.05 mg/mL for Thorium. PCST ion exchanger could separate 225Ac from isotopes of Ra and Th, and the process represents an interesting one step separation that could be used in an 225Ac generator from 225Ra and/or 229Th. Capacity studies indicated PCST could be used to separate 225Ac produced on small 226Ra targets (0.3–1 g), but PCST did not have a high enough capacity for production scale Th targets (50–100 g).

Highlights

Ion-exchange chromatography has been successfully used to separate radioisotopes for medical applications, nuclear fuel reprocessing and other applications[1,2]
Production of 225Ac has been of particular interest recently since efficacy of this material has been demonstrated in a treatment of certain types of cancer. 225Ac can be made available by several routes: separation from 229Th/225Ra generator, by high energy (100–200 MeV) proton irradiation of natural Thorium target, or by irradiation 226Ra target with low energy proton (10–24 MeV)[7,8]
Optimal conditions for the separation on poorly crystalline Crystalline silicotitanate (CST) (PCST) inorganic ion-exchanger were evaluated with a representative sample containing 225Ac, 227Th, and 223Ra

Summary

Introduction

Ion-exchange chromatography has been successfully used to separate radioisotopes for medical applications, nuclear fuel reprocessing and other applications[1,2]. The separation presents challenges if no ion exchange resins are available that have more selective for the isotope of interest rather than the target material. The CST inorganic ion exchangers were initially developed in the 1960s and have been evaluated for nuclear waste treatment due to the materials remarkable selectivity toward Cs and Sr13–15. Studies showed that Cs and Sr2+ cations demonstrate higher rate of uptake by poorly crystalline CST compared to the crystalline form. This was attributed to the higher surface area and smaller particle size, which was highlighted to account for the increased rate even though there would be www.nature.com/scientificreports/. The high selectivity of CST ion exchanger for Cs and Sr was used to decontaminate the Fukushima site[16]

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