Detection and quantification of fission products can provide valuable information for nuclear forensics, but a thorough understanding of their chemistries in the environment is key for appropriate analyses and conclusions.  As part of the 6% fission yield of the 99 isobar and with a half-life of 213,000 years, technetium-99 can be a useful tool for nuclear forensics. While Tc(VII) is highly water soluble, in excess of 11 mol/L, Tc(IV) has only sparing solubility, on the order of 10<sup>-8 </sup>mol/L. These vast differences in solubility makes reductive precipitation of Tc(VII) to Tc(IV) an appealing method for limiting Tc mobility in environmental systems. However Tc(IV) readily oxidizes in the presence of oxygen and ligand complexation has been shown to greatly affect Tc(IV) dissolution and, to some extent, its oxidation. This work utilizes a competitive aqueous/organic extraction method to determine the stability constants of Tc(IV) with diethylene triamine pentaacetic acid (DTPA), which is then used to model Tc(IV) total dissolution as a function of DTPA concentration. The modeled dissolution of Tc(IV) is then compared to experimentally determined Tc(IV) dissolution in presence of DTPA. These determinations are part of a larger project seeking to improve the accuracy of modelling technetium mobility in environmental systems. This research was funded by the Defense Threat Reduction Agency through grant # HDTRA1-12-0014.<br/>

Stability constants and total dissolution of Tc(IV) and DTPA complexes

249th National Meeting (2015)

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