Redox interactions of technetium with neptunium in acid solutions

Abstract

Redox interaction of reduced technetium forms and technetium(VII) with neptunium(III), neptunium(IV) and neptunium(VI) have been investigated using electrochemical and spectroscopic (Vis–NIR) techniques. The neptunium species most stable in 4 M H2SO4, i.e. Np(IV) ions, do not reduce Tc(VII) in contrast to Np(VI) ions which oxidize Tc(IV) species to Tc(VII). The interaction of pertechnetates with Np(III) leads to formation of Tc(IV) species. The Vis–NIR measurements showed the generation of intermediate Tc(V) and Np(V) forms during the oxidation of Tc(IV) and competitive reduction of Np(VI). Tc(V) and Np(V) forms are characterised by the bands at 460 and 980 nm respectively.

The Removal of Pertechnetate from Aqueous Solution by Synthetic Hydroxyapatite: The Role of Reduction Reagents and Organic Ligands

“…High oxidation-state species can form volatile compounds that are particularly difficult in aspects of the nuclear fuel cycle [ 28 ]. The most stable and characteristic oxidation state of Tc in weakly acidic, neutral and basic environments is Tc(VII) occurring in the form of pertechnetate ion TcO₄ − , which was also proved by Chotowski [ 29 ]. Tc(IV) can occur in aqueous solutions as TcO 2+ , TcO(OH) + and TcO(OH) 2 , depending on the pH value.…”

New insight on the simultaneous H2and HNO2production in concentrated HNO3aqueous solutions under alpha radiation

“…Moreover, when using internal a particle emitters, radionuclides-specic yields have been recorded due to the progressive disproportionation as a function of the nitric acid concentration induced by the complexing nature of HNO 3 and its chemical involvement in the investigated processes. 46,49,[104][105][106][107][108][109][110][111][112][113] Simultaneously, investigations using radionuclides may pose exposure and contamination risks to the manipulators and require special equipment for safe handling that render them cumbersome. At the same time, questions are imposed about loss of products during handling.…”