Contact

Caroline Börner

c.boernerAthzdr.de
Phone: +49 351 260 2251

Promotionsarbeiten

Interaction of organometallic Tc with metabolites and Fe(II) minerals

Ph.D. student:

Caroline Börner

Supervisors:

Dr. Natalia Mayordomo Herranz, Prof. Dr. Thorsten Stumpf (HZDR)

Department:

Surface processes

Period:

since 02/2024

The nuclide 99Tc is part of the high radioactive waste originated in nuclear power plants, since it is a fission product of 235uranium and 239plutonium.[1] For the storage of this waste in a deep geological waste repository, it is intended to use a multiple barrier system to prevent the migration of radioactive elements into the biosphere. The safety assessment of such repository in Germany is performed for one million years. In the worst case scenario, water ingress could alter the integrity of the repository and mobilise radionuclides.[2] It is necessary to know the chemical behaviour of the radionuclides inventory, among others 99Tc, in contact with possible barriers present in the repository in order to understand retention processes and finally improve the safety assessment.

Additionally, trace amounts of 99Tc are daily discharged into the sewage since it is the daughter nuclide of the metastable isomer 99mTc, which is used in nuclear medicine as a contrasting agent.[3] For this purpose, Tc complexes in low oxidation states stabilised by complexing ligands are used.[4] As an example, [TcI(CO)3(H2O)3]+ is a precursor.

The medicinal properties of many Tc complexes in low oxidation states are known, because of intensive studies in this field.[4] However, the knowledge about their behaviour in the environment is not known yet. Despite their low concentration in the nanomolar range, the effects of these complexes on the environment are not well known and from a radioecological point of view there is the possibility of bioaccumulation and accumulation of 99Tc in the human food chain.[5]

The studies dealing with the remediation of Tc focus on the reduction of the mobile, oxidised pertechnetate anion (TcVIIO4−) to less soluble Tc(IV) species, such as TcIVO2.[6] However, there are no environmental studies dealing with the uptake of complexes of Tc in lower oxidation states by minerals.

During my PhD studies, the interaction of organometallic Tc complexes with iron(II) minerals in presence and absence of metabolites will be studied. The main goals are i) analysing the removal of Tc by an iron(II) mineral under varying conditions, e.g. the Tc oxidation state or concentrations, the presence of metabolites, or pH and ii) studying the formation of soluble complexes of Tc in lower oxidation states with metabolites. The Tc-mineral interaction will be investigated on a macroscopic and molecular level. Therefore, various techniques are to be used to characterise and analyse the Tc-containing solids and liquids. This includes several spectroscopic and analytical techniques, like nuclear magnetic resonance spectroscopy, infrared spectroscopy, Raman microscopy, liquid scintillation counting, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy at the Rossendorf beamline at the European Synchrotron Radiation Facility.

The Ph.D. research is developed in the frame of the NukSiFutur Young Investigators group TecRad (02NUK072), funded by the German Federal Ministry of Education and Research (BMBF).

  1. A. H. Meena et al., Environ. Chem. Lett. (2017), 15, 241–263.

  2. Standortauswahlgesetz vom 5. Mai 2017 (BGBl. I S. 1074), das zuletzt durch Artikel 8 des Gesetzes vom 22. März 2023 (BGBl. 2023 I Nr. 88) geändert worden ist.

  3. O. K. Hjelstuen, Analyst (1995), 120, 863–866.

  4. R. Alberto & U. Abram, Handbook of Nuclear Chemistry, Springer, (2011).

  5. R. Alberto et al. J. Am. Chem. Soc. (2001), 123, 3135–3136.

  6. C. I. Pearce et al. Sci. Total Environ. (2020), 716, 132849.