Ph.D. topics

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Investigation of the influence of Al(III) on the sorption of trivalent minor actinides on feldspar

Jessica Lessing

Prof. Dr. Thorsten Stumpf, PD Dr. habil. Moritz Schmidt (HZDR)

Chemistry of the f-elements

04/2022-03/2025

The present work is part of the KURSIV project (Competition and Reversibility in Sorption Processes, funded by the BMUV), which deals with the retention of radionuclides on mineral phases. The focus is on feldspars, as studies have shown that feldspars with different calcium contents have varying surface properties, which influences their sorption properties [1]. An in-depth understanding of these interactions is crucial in order to find a suitable host rock for the final disposal of radioactive waste.

In my doctoral thesis I am investigating the influence of aluminum on the sorption of trivalent minor actinides on feldspars. The rare earths europium (Eu) and yttrium (Y), which are non-radioactive homologs of americium (Am) and curium (Cm), are mainly used as sorbents. Alongside quartz and mica, feldspars are an essential component of crystalline rocks that are being considered as potential host rocks for radioactive repositories.

High-resolution surface X-ray diffraction (more precisely CTR and RAXR) is used to investigate the processes on the mineral surface. These in-situ methods enable an exact determination of the electron density on the surface and thus contribute to a better understanding of the sorption mechanisms. Microscopy and spectroscopy are also used to better characterize the surface and the species bound to it.

Reference

1. Lessing, J. Neumann, J. Lützenkirchen, F. Bok, S. Moisei-Rabung, D. Schild, V. Brendler, T. Stumpf, M. Schmidt, Natural and synthetic plagioclases: Surface charge characterization and sorption of trivalent lanthanides (Eu) and actinides (Am, Cm). Colloids & Surfaces A. (2024) DOI: 10.1016/j.colsurfa.2024.133529

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