Speciation of Technetium Dibutylphosphate in the Third Phase Formed in the TBP/HNO 3 Solvent Extraction System

• Published in: ACS omega Vol. 9; no. 13; pp. 15527 - 15534
• Main Authors: George, Jonathan, Salcedo, Ramsey, Greenberg, Rachel, Elshendidi, Hossam, McGregor, Donna, Burton-Pye, Benjamin, Francesconi, Lynn C, Paulenova, Alena, Gelis, Artem V, Poineau, Frederic
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 02.04.2024
• ISSN: 2470-1343; 2470-1343
• DOI: 10.1021/acsomega.4c00393

The speciation of technetium in the nitric acid/dibutylphosphoric acid (HDBP)- -dodecane system was studied by extended X-ray absorption fine structure (EXAFS) spectroscopy and theoretical methods. Tetravalent technetium, produced by the hydrazine reduction of TcO in 3 M HNO , was extracted by HDBP in -dodecane (30% by volume). During extraction, the splitting of the organic phase into a heavy phase and a light phase was observed. EXAFS analysis is consistent with the presence of Tc(NO ) (DBP)(HDBP) in the light phase and Tc(NO ) (DBP) (HDBP) in the heavy phase. Density functional theory calculations at the B3LYP/6-31G* level confirm the stability of the proposed species and indicate that stereoisomers -mer- and fac-Tc(NO ) (DBP)(HDBP) for the light phase and cis- and trans-Tc(NO ) (DBP) (HDBP) for the heavy phase] could coexist in the system (in the -dodecane solution). Mechanisms of formation of Tc(NO ) (DBP)(HDBP) and Tc(NO ) (DBP) (HDBP) are proposed.