1. XAFS Study of the Chemical and Structural States of Technetium in Fe(III) Oxide Co-Precipitates
- Author
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John M. Zachara, Byong-Hun Jeon, James P. McKinley, Ravi K. Kukkadapu, Steve M. Heald, and Dean A. Moore
- Subjects
Chemical state ,Oxide minerals ,chemistry.chemical_compound ,Valence (chemistry) ,Aqueous solution ,Precipitation (chemistry) ,Chemistry ,Oxide ,Redox ,Nuclear chemistry ,X-ray absorption fine structure - Abstract
XAFS has been used to study the chemical state and structural environment of technetium in Fe(III) oxide co‐precipitates. 99Technetium is an abundant fission product which poses a significant environmental hazard due to its long half‐life, abundance in nuclear wastes, and environmental mobility as the pertechnetate ion [Tc(VII)O4−] under oxidizing conditions. Tetravalent Tc [Tc(IV)] is the stable valence state under reducing or anoxic conditions where its environmental mobility is significantly lowered by formation of a sparingly soluble, hydrated amorphous oxide precipitate [Tc(IV)O2⋅nH2O(s)]. We have been studying the kinetics and solid products resulting from abiotic reduction of Tc(VII)O4− by aqueous, adsorbed, and structural Fe(II) to provide insights on Tc migration in microaerophilic groundwaters. The reduction reaction yields Fe/Tc precipitates of variable structures that have not been previously studied. For the homogeneous reaction with aqueous Fe(II) at relatively high Tc:Fe concentrations, the...
- Published
- 2007
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