Abstract
Technetium-99 (Tc) is a long-lived isotope produced in high yield from the fission of U-235 and Pu-239, contributing significantly to nuclear waste doses. It is also a decay product of Tc-99m, a widely used medical radioisotope, which is regularly discharged into sewage. The environmental release of Tc-99 raises health concerns due to prolonged exposure risks.
Immobilization of Tc is mainly achieved through redox state changes, reducing mobile Tc (VII) (TcO₄⁻) to less soluble Tc (IV) species (e.g., TcO₂, TcSₓ) via interaction with minerals like FeII-sulfides, layered double hydroxides, or magnetite. However, complexing ligands (e.g., carbonate) can hinder Tc immobilization.
At Helmholtz-Zentrum Dresden-Rossendorf, our group studies Tc biogeochemistry through interactions with microorganisms, metabolites, and Fe (II) minerals to simulate environmental conditions. This talk will cover: i) Tc immobilization by biogenic vs. synthetic vivianite, ii) structural insights into Tc (IV) and Tc (III) carbonate complexes, and iii) the impact of metabolites on Tc removal by pyrite.
In addition, we are developing methods to visualize in situ the redox triggered reactions in solution by coupling spectroscopy and electrochemistry. Some of our updated results will be shown.
Bio
Natalia Mayordomo Herranz, Ph.D.
Group Leader
Helmholtz-Zentrum Dresden-Rossendorf
Dr. Natalia Mayordomo Herranz: I obtained my bachelor (licenciate) degree at Universidad de Alcalá (Spain) in 2010. At the same University, I finished my master’s degree in 2011. In 2012 I started my Ph.D. at the Center of energetic, environmental and technological research (CIEMAT) in Madrid (Spain). My PhD dealt with the experimental and theoretical sorption of Se (IV), Sr (II), Cd (II), and U(VI) on mixtures of alumina and bentonite. After finishing my PhD in 2017, I started my postdoc at Helmholtz-Zentrum Dresden-Rossendorf (HZDR, in Dresden Germany), where I have been mainly focused on Tc immobilization. Since July 2022 I am a young investigator group leader. I gain a 2 M€ grant to have my team mainly working on Tc biogeochemistry, and the improvement on understanding of redox-triggered processes. I also lecture at Technische Universität Dresden (Germany), and I am enrolled on writing my habilitation.