Format

Send to

Choose Destination
See comment in PubMed Commons below
J Environ Radioact. 2004;74(1-3):211-9.

X-ray absorption spectroscopy studies of reactions of technetium, uranium and neptunium with mackinawite.

Author information

  • 1Centre for Radiochemistry Research, Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK. francis.livens@man.ac.uk

Abstract

Technetium, uranium and neptunium may all occur in the environment in more than one oxidation state (IV or VII, IV or VI and IV or V respectively). The surface of mackinawite, the first-formed iron sulfide phase in anoxic conditions, can promote redox changes so a series of laboratory experiments were carried out to explore the interactions of Tc, U and Np with this mineral. The products of reaction were characterised using X-ray absorption spectroscopy. Technetium, added as TcO4(-), is reduced to oxidation state IV and forms a TcS(2)-like species. On oxidation of the mackinawite in air to form goethite, Tc remains in oxidation state IV but in an oxide, rather than a sulfide environment. At low concentrations, uranium forms uranyl surface complexes on oxidised regions of the mackinawite surface but at higher concentrations, the uranium promotes surface oxidation and forms a mixed oxidation state oxide phase. Neptunium is reduced to oxidation IV and forms a surface complex with surface sulfide ions. The remainder of the Np coordination sphere is filled with water molecules or hydroxide ions.

PMID:
15063549
DOI:
10.1016/j.jenvrad.2004.01.012
[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science
    Loading ...
    Support Center