Correlation between X-ray chemical shift and partial charge in Tc(IV) complexes: Determination of Tc partial charge in TcnOy(4n−2y)+Tc_nO_y^{(4n-2y)+}

The chemical shift of the X-ray absorption K-edge of Tc(IV) complexes determined by X-ray Absorption Spectroscopy (XAS) measurement was studied. A correlation between edge position (ΔE) and partial charge on Tc atoms (δTc) was determined. This correlation was used to determinate δTc in TcnOy(4n-2y)+. Furthermore, a theoretical relation between δTc and the charge of TcnOy(4n-2y)+, was also established and the overall charge of this complex was estimated

Photochemical behaviour of Tc2_2OCl104–_{10}^{4–} and TcnOy4n–2y+_nO_y^{4n–2y+} in chloride media

The stabilities of the technetium polymers Tc2OCl104− and TcnOy4n−2y+ have been studied under light irradiation in 3 M chloride media with a pH range from 0 to 1.3. It has been shown that under irradiation, Tc2OCl104− is not stable and undergoes dissociation to TcCl5(H2O)- at pH = 0 and pH = 0.3. At pH = 1, irradiation of Tc2OCl104− leads to a stationary state involving TcCl5(H2O)- and Tc2OCl104−. At pH = 1.3, TcnOy4n−2 y+ remains stable under irradiation. Under light irradiation, the predominance diagram of Tc(IV) species obtained from Tc2OCl104− aquation in a pH range from 0 to 1 is drawn. The chemical behaviour of Tc2OCl104− and the influence of the light on the condensation of Tc(IV) and solubility of TcO2· x H2O are discussed

Condensation mechanisms of tetravalent technetium in chloride media

The condensation mechanisms of tetravalent technetium in chloride media were studied in the pH range 0–1.5. A new dimer complex of Tc(IV) has thus been discovered, Tc2OCl104−. Spectroscopic and kinetics studies showed that the formation of this compound resulted from the condensation of TcCl5(H2O)−. An EXAFS study indicates that the dimer displays a [Tc-O-Tc]6+ structure. As the pH increases, UV-visible measurements showed a cyclization of [Tc-O-Tc]6+ into [Tc(μO)2Tc]4+ leading, in fine, to the precipitation of TcO2·x H2O. The aquation constant (Kaq) of TcCl62− into TcCl5(H2O)− and the dimerisation constant (logKdim) of TcCl5(H2O)− into Tc2OCl104− were determined to be 2.20±0.26 and 4.68±0.09, respectively

The Nature of the Volatile Technetium Species Formed During Vitrification of Borosilicate Glass

Vitrification of sodium pertechnetate into borosilicate glass was performed in air at 1100 °C. A glass with a composition similar to the one developed for vitrification of the low activity waste at the Hanford site was used. A red volatile species was observed above 600 °C. The extended X-ray absorption fine structure results indicate the environment of the absorbing Tc atom consists of 2.9(6) O atoms at 1.73(2) Å, 2.2(4) O atoms at 2.02(2) Å, and 0.8(2) O atoms at 2.18(2) Å. The results are consistent with the presence of a mononuclear species with a structure closely related to TcO3(OH)(H2O)2

Speciation of Tc(IV) in chloride solutions by capillary electrophoresis

Browse Search My Profile Activate Help Home > List of Issues > Table of Contents > Abstract Speciation of Tc(IV) in chloride solutions by capillary electrophoresis Author(s): Xiaolan Liu | Frédéric Poineau | Massoud Fattahi | Bernd Grambow | L. Vichot doi: 10.1524/ract.93.5.305.64276 View PDF article (245 K) View table of contents Email this link Add to my alerts What is RSS? Trouble viewing articles as PDF? Radiochimica Acta Print ISSN: 0033-8230 Volume: 93 | Issue: 5/2005 Cover date: 20050501 Page(s): 305-309 Abstract text A method for speciation of Tc(IV) species (TcCl62− and TcCl5(H2O)−) in chloride solutions, using capillary electrophoresis (CE) technique was developed. The proposed method has overcome the difficulties of unstable oxidation states analysis by shortening their travel time in the capillary. TcCl62− and TcCl5(H2O)− were thus separated without being hydrolyzed and polymerized, and their UV/Vis spectra were recorded. With a 1 M HCl/NaCl buffer solution (pH=1), the electrophoretic mobilities were determined as 5.47×10−4 cm2/Vs for TcCl62− and 2.13×10−4 cm2/Vs for TcCl5(H2O)− at 25 °C. The total analysis time for one run is 12 minutes