Behaviour of 99Tc in aqueous solutions in the presence of iron oxides and microorganisms

A set of experiments was performed to determine the factors that influence TcO4− interaction with Fe-bearing minerals and to explore the effect of microbial activity on the behaviour of Tc(VII) in solution, in the presence of iron oxides under oxidizing medium. Gradual sorption of TcO4− (aq) onto wustite/magnetite was observed under alkaline conditions (pH 8–9). No pronounced effect of TcO4− (aq) interaction with hematite was observed in the investigating alkaline systems. At low pH values (2.7–4.5), TcO4− retention on hematite increases, suggesting that the process is dependent on pH. Sorption of 99Tc (VII) onto hematite at pH 7.6–8.0 was achieved because of the presence of specific microorganisms. - Highlights: • Abilities of wustite/magnetite and hematite to accumulate 99Tc(VII) were investigated. • The effect of microbial activity on the migration behaviour of technetium was tested. • Gradual sorption of [99Tc] TcO4− from aquatic solution onto wustite/magnetite (FeO/Fe3O4) under aerobic conditions was observed. • Specific microorganisms induced sorption of 99Tc(VII) by hematite