Technetium interaction in solution with carbonate or at the mineral-water interface with vivianite

The fate of technetium (Tc) in the environment is of great concern due to its inherent radioactivity, being a hazardous material for living organisms. Tc is especially mobile as Tc(VII), but its migration is limited when it is reduced to Tc(IV) by electrochemical methods or by reductants e.g., Fe(II). Furthermore, the migration of Tc depends on the aqueous chemical speciation and the interaction of Tc with surfaces such as minerals or microorganisms. Our proposal is focused in two directions.
First, we have studied the redox aqueous chemistry of Tc carbonates. For the first time, we have observed the presence of Tc(V)-carbonate by Tc-99 NMR. We want to determine its structure by XAS.
Second, we have studied the immobilitzation of Tc by vivianite (Fe(II)-phosphate). The vivianites used in the experiments were synthetically and biogenically produced. We want to decipher the mechanism responsible of Tc immobilization, that might be influenced by pH due to mineral transfromation.