Reduction and immobilization processes of contaminants (Se, Tc, Pu) by Fe(II)-bearing minerals

Fe(II)-bearing phases are naturally occuring in most anoxic aquifers, and form also at the surface of corroding steel containers under typical nuclear waste repository conditions. Due to their ability to reduce metal and metalloid contaminants, they are expected to play a key role for the migration behaviour of a wide range of radionuclides, including actinides and fission products. Using X-ray absorption spectroscopy as main tool, we have studied reaction end products, mechanisms and kinetics of redox processes at a range of water/mineral interfaces, including magnetite, green rust, mackinawite, chukanovite, and Fe2+-sorbed clays, but also in more redox-inert systems like cement.
Our results show that the electron transport within mineral structures and at the surface is controlling the extent and the kinetics of multi-electron redox reactions.