Catalytic reduction of pertechnetate (99TcO4
 -) insimulated alkaline nuclear wastes

Bernard, Jonathan G.; Bauer, E.; Richards, Monique; Arterburn, Jeffrey B.; Chamberlin, Robert W.

doi:10.1524/ract.2001.89.1.059

Cited by 19 publications

(23 citation statements)

References 9 publications

(6 reference statements)

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“…The use of irradiation in these experiments does not imply a similar mechanism for reduction of TcO 4 -in high-level waste tanks. Both chemical (Bernard, Bauer et al 2001) and radiolytic ) pathways exist for reduction of TcO 4 -under these conditions, but the radiation-chemical pathway is different from the pathway that is operative here, direct reduction of TcO 4 -by hydrated electrons from the radiolysis of water.…”

Section: Introductionmentioning

confidence: 71%

Research Program to Investigate the Fundamental Chemistry of Technetium

Shuh¹,

Pegg²

2000

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Section: Introductionmentioning

confidence: 71%

Research Program to Investigate the Fundamental Chemistry of Technetium

Shuh¹,

Pegg²

2000

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“…It has been shown that in the presence of the noble metals (ruthenium, rhodium, and/or platinum), alkaline pH, elevated temperatures, and organic molecules, catalytically active metals are formed that are capable of reducing pertechnetate (Bernard et al 2001). The catalytically active metals in the presence of hydrogen only were also shown to be competent at pertechnetate reduction.…”

Section: Sy 103mentioning

confidence: 99%

“…Noble metals. Simulant work has indicated that in the presence of the noble metal precipitates, organic complexants themselves can reduce pertechnetate to form alkaline soluble technetium compounds (Bernard et al 2001). …”

Section: The Presence Of Soluble Transuranic Elementsmentioning

confidence: 99%

Development of a Chemistry-Based, Predictive Method for Determining the Amount of Non-Pertechnetate Technetium in the Hanford Tanks: FY 2012 Progress Report

Rapko¹,

Bryan²,

Bryant³

et al. 2013

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Executive SummaryThis report describes investigations directed toward understanding the extent of the presence of highly alkaline soluble, non-pertechnetate technetium (n-Tc) in the Hanford Tank supernatants. The goals of this report are to: a) present a review of the available literature relevant to the speciation of technetium in the Hanford tank supernatants, b) attempt to establish a chemically logical correlation between available Hanford tank measurements and the presence of supernatant soluble n-Tc, c) use existing measurement data to estimate the amount of n-Tc in the Hanford tank supernatants, and d) report on any likely, processfriendly methods to eventually sequester soluble n-Tc from Hanford tank supernatants.The work described herein follows on a substantial literature developed in the 1990s and early 2000s that first identified the problem of the presence of n-Tc and led to a tentative identification of the species in at least two Hanford tank waste supernatants. This project attempted to correlate chemically relevant indicators for which quality-valid data exists in the TWINS database suitable for eventual extrapolation to as-yet untested tank supernatants. In addition, two other tangential tasks were undertaken. First, a model was developed that expanded upon a previously published model by Lukens et al. (2001), for the rate of reduction of pertechnetate by radiolysis and inorganic chemical-based processes. Using information obtained from TWINS, this model was applied to the Hanford tank supernatants to identify the rate of pertechnetate reduction in the various Hanford tank supernatants. Second, one proposed species for n-Tc, the complex [(CO) 3 Tc(H 2 O) 3 ] + , was prepared, and initial studies into its spectroscopic signature and chemical stability were performed.From this work, the only acceptable chemically based correlations with data from the TWINS database were that the fraction of n-Tc present negatively correlates with either of two, closely related variables: total dose experienced in the tank, and 137 Cs concentration in the tank supernatants. The observed inverse correlation is counterintuitive, but a possible explanation is discussed. However, the correlation should lend some insight as to which tanks might be tested to further validate and enhance the predictive value of this correlation.As noted above, chemical data, radiolysis constants and known chemical rate constants for the reaction of water radiolysis products with inorganic Hanford tank waste supernatant constituents were used to evaluate the relative rates of pertechnetate reduction in the Hanford tank supernatants. These results are summarized in the report. Interestingly, the reduction rate for pertechnetate is greatest in two tanks, AZ-101 and AZ-102, where the presence of n-Tc is not detected. However, this reduction only concerns the rate of pertechnetate reduction; the speciation of the reduced product is not addressed. Consequently, reduction of pertechnetate to the poorly alkaline-soluble technetium dioxide could ...

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“…Reduced forms of Tc can form complexes with these chelators, and they have characteristic UV-Vis absorbance spectra [38]. If catalytic metal salts are also present, TcO 4 − may be quantitatively reduced to TcO 2 [39].…”

Section: Effects Of Chelating Agentsmentioning

confidence: 99%

Potential interferences on the pertechnetate-sulfide immobilization reaction

Liu

Terry

Jurisson³

2009

Radiochimica Acta

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Technetium-99 / Pertechnetate / Immobilization / Sulfide / InterferencesSummary. The potential interference from competing inorganic anions, chelating agents, and low molecular weight organic acids (LMWOAs), and the potential surface effects of selected minerals on the TcO 4 − -sulfide immobilization reaction (to form Tc 2 S 7 ) were investigated. The presence of the common inorganic anions, such as nitrate, studied did not affect the TcO 4 − -sulfide immobilization process even though their concentrations were 20 times higher than that of sulfide. The chelating agents relevant to nuclear waste sites (e.g., ethylenediaminetetraacetic acid) did not compete with the TcO 4 − -sulfide reaction even in high excess. Of the ten selected LMWOAs investigated, only maleic acid and fumaric acid were able to inhibit the immobilization process by forming anionic water-soluble complexes with pertechnetate at concentrations significantly higher than found in the environment. None of the non-reducing minerals (e.g., goethite) investigated interfered with the immobilization reaction. X-ray absorption spectroscopy showed that the product obtained in the presence of the selected co-existing species was predominantly Tc 2 S 7 .

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Catalytic reduction of pertechnetate (⁹⁹TcO₄ ^-) insimulated alkaline nuclear wastes

Cited by 19 publications

References 9 publications

Research Program to Investigate the Fundamental Chemistry of Technetium

Research Program to Investigate the Fundamental Chemistry of Technetium

Development of a Chemistry-Based, Predictive Method for Determining the Amount of Non-Pertechnetate Technetium in the Hanford Tanks: FY 2012 Progress Report

Potential interferences on the pertechnetate-sulfide immobilization reaction

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Catalytic reduction of pertechnetate (99TcO4 -) insimulated alkaline nuclear wastes

Cited by 19 publications

References 9 publications

Research Program to Investigate the Fundamental Chemistry of Technetium

Research Program to Investigate the Fundamental Chemistry of Technetium

Development of a Chemistry-Based, Predictive Method for Determining the Amount of Non-Pertechnetate Technetium in the Hanford Tanks: FY 2012 Progress Report

Potential interferences on the pertechnetate-sulfide immobilization reaction

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Catalytic reduction of pertechnetate (⁹⁹TcO₄ ^-) insimulated alkaline nuclear wastes