Contact
Janis Wolf
j.wolf
hzdr.de
Phone: +49 351 260 2282
Ph.D. topics
Developing Methods for Characterization of Protactinium-231 in Environmental Samples
Janis Wolf
Prof. Dr. Anton Wallner (FWIR), Dr. Sebastian Fichter (FWIR), Dr. Robin Steudtner (FWOB), Dr. Astrid Barkleit (FWOG-I)
Institute of Ion Beam Physics and Materials Research: Department of Accelerator Mass Spectrometry and Isotope Research
09/2022-08/2025
The goal of the shared PhD project between the Institute of Ion Beam Physics and Materials Research and the Institute of Resource Ecology is to find new pathways for characterizing the quantity and speciation of protactinium-231 in the environment. This project is partially funded by HZDR’s board of directors program for connecting different institutes by shared PhD students ("Vernetzungsdoktoranden").
Protactinium (Pa) is a naturally occurring radionuclide being part of the natural decay chain of uranium-235. In general, its behavior is not well-studied but it may play an important role in estimating the long-term radiotoxicity in the environment. The physico-chemical behavior of Pa fundamentally differs from that of other actinides. While Pa, in the +IV oxidation state, exhibits similarities with the tetravalent actinides thorium and uranium, Pa primarily appears as a monooxocation [Pa=O]3+ in the +V oxidation state. The latter is more reminiscent of the Group V elements niobium and tantalum and is significantly distinct from the chemistry of actinyl(V,VI) cations (dioxoactinyl units [O=An=O]+/2+). Therefore, transferring the properties of the more extensively studied actinyls to the behavior of Pa(V) is not possible.
Together with the Department of Accelerator Mass Spectrometry and Isotope Research, a method for the detection of ultra-low levels of 231Pa in the environment will be developed. Measurements of 231Pa will be conducted at the new compact AMS facility HAMSTER, designed specifically for the detection of actinides. The focus of this thesis is on the optimization of the measurement technique of 231Pa and the development of separation procedures for Pa from environmental samples.
At the Institute of Resource Ecology, we will investigate the spectroscopic absorption and fluorescence properties of Pa using various methods, including time-resolved laser-induced fluorescence spectroscopy (TRLFS), UV/Visible spectroscopy (UV/Vis), Fourier-transform infrared spectroscopy (FT-IR), and X-ray absorption spectroscopy (XAS).
This combination of mass spectrometric and spectroscopic methods will not only enable the quantification of 231Pa in the environment but also shed light onto the speciation of Pa-compounds on the molecular level, thus enabling us to describe the migration pattern of Pa in the environment.
