Published online by Cambridge University Press: 25 February 2011
The speciation of UO2 2+ and UO2 2+/ TBP mixtures has been investigated in solution and intercalated with the reference smectite clay SAz-1 using x-ray absorption, Raman, andluminescence spectroscopies. Neither aquated UO2 2+ nor its TBP complex undergoes any detectable changes in uranium oxidation state on intercalation. Further, at the pH values employed in this work, there is no evidence for hydrolysis of the uranium species to generate dimeric or higher order uranium oligomers. However, we do find indications that the structures of the solution complexes are altered on intercalation, particularly for the UO2 2+TBP system and for more dilute UO2 2+/aqueous systems. In addition, several lines of evidence suggest that, at the loading levels used in this study, the uranyl species is interacting with two or more spectroscopically distinguishable sites on SAz-1.