• journal_title：Mineralogical Magazine
• Contributor：N. D. M. Evans ; R. Hallam
• Publisher：Mineralogical Society of Great Britain and Ireland
• Date：2012-12-01
• Format：text/html
• Language：en
• Identifier：10.1180/minmag.2012.076.8.56
• journal_abbrev：Mineralogical Magazine
• issn：0026-461X
• volume：76
• issue：8
• firstpage：3435
• section：Radionuclide transport

d="p-2">In the UK, technetium may be disposed of in a high pH, low Eh cementitious repository. In such a scenario, its chemistry would be dominated by mula" id="inline-formula-1">mg class="math mml" alt="Formula" src="3435/embed/mml-math-1.gif" /> , in aerobic conditions and the sparingly soluble TcO_2(s) in anaerobic conditions. Repository heterogeneity could mean that both Tc(VII) and Tc(IV) are present simultaneously. The anthropogenic ligands EDTA and picolinic acid are commonly used as decontamination agents and are likely to be present in intermediate-level waste (ILW). They could complex with Tc(IV) increasing its aqueous concentration and mobility in the cement porewaters and beyond. The conditional stability constants (measured in 0.3 mol dm⁻³ NaOH) for the Tc(IV)–EDTA and Tc(IV)–picolinic acid complexes have been determined to be: β_{Tc(IV)−EDTA} = 1.6 × 10²⁶, which corresponds to log β = 25.2±0.6; and β_Tc(IV)−PA = 8.65 × 10, which corresponds to log β = 26.9±0.1, respectively.