Multiple Ion Exchange Column Tests for Technetium Removal from Hanford Site Tank 241‐AW‐101 with Superlig<sup>®</sup>639 Resin

Hassan, Neguib M.; Adu-Wusu, K.; Nash, C. A.; Marra, James C.

doi:10.1081/sei-120039636

Cited by 13 publications

(6 citation statements)

References 20 publications

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“…Although many of these resins have been shown to be effective at pertechnetate removal from high sodium nitrate and nitrite solutions, SuperLig® 639 is the most studied of the successful resins with actual Hanford tank supernatants (Robbins and McCabe 2013) and therefore is the recommended material for this testing. From existing test results (for example AW-101 testing), well over 40 bed volumes of supernatant can be passed through a SuperLig® 639 column before significant breakthrough of pertechnetate is observed (Hassan et al 2003).…”

Section: Approach/discussionmentioning

confidence: 99%

Protocol for Identifying the Presence of and Understanding the Nature of Soluble, Non-pertechnetate Technetium in Hanford Tank Supernatants

Rapko¹

2014

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Executive SummaryThe purpose of this report is twofold: first, to propose a test protocol for identifying the presence of soluble, non-pertechnetate Tc (n-Tc) in alkaline, high ionic strength, Hanford tank supernatants, and second, to evaluate various methods of obtaining information about the nature of the identified, non-pertechnetate species.The proposed protocol addresses three questions: 1) is n-Tc present and what fraction of the total soluble Tc is present in this form, 2) is there an interference at m/e 99 in the inductively coupled plasma mass spectrometry (ICP-MS) that gives false positives in a test for n-Tc, and 3) is there another isotope that could act as an interference in a test for n-Tc by liquid scintillation counting.For ALARA (as low as reasonably achievable) reasons, the protocol involves an initial Cs decontamination by contact with the Cs selective IE-911 ion exchanger. It is recommended that the Cs-depleted supernatant be spiked with a non-Tc-99 source (likely Tc-99m) of pertechnetate to allow an independent assessment of pertechnetate and total technetium behaviors during the test. The solution is then passed through a column containing a pertechnetate getter. Because of its extensive use with Hanford tank waste supernatants, SuperLig® 639 is recommended as the pertechnetate getter. The resulting effluent is sampled for analysis by gamma energy analysis, liquid scintillation counting for beta activity, and ICP-MS for its mass 99 concentration.Should there be a significant difference in pertechnetate versus total technetium behavior, the effluent is exhaustively oxidized by a persulfate/microwave digestion, adjusted as needed in composition, passed again through an appropriate pertechnetate getter, and resampled. From analysis of these sample results, the questions posed above can be addressed.The report concludes with an evaluation of a variety of spectroscopic methods that might be used either to identify n-Tc spectroscopically in Hanford tank waste supernatant or to gain insight into the chemical structure of n-Tc. It is concluded that most methods evaluated either are unsuitable, sufficiently insensitive to preclude use at the technetium concentrations present in Hanford tank waste supernatant, or would require significant methods development before they might be effective in n-Tc species analysis. The two methods currently available that can supply useful speciation information are X-ray absorption spectroscopy (of various types) and Tc-99 nuclear magnetic resonance spectroscopy.

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Section: Approach/discussionmentioning

confidence: 99%

Protocol for Identifying the Presence of and Understanding the Nature of Soluble, Non-pertechnetate Technetium in Hanford Tank Supernatants

Rapko¹

2014

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“…[9][10] Besides, deep removal of hazardous and radioactive TcO4 -(ReO4 -is used as its structural surrogate) is of particular importance in nuclear waste management to avoid potential enviorenment pollutants. [11][12] These provide an incentive to develop new strategies that might allow low-content (at the ppm level) rhenium to be effectively and selectively isolated from rhenium-bearing resources, such as the leaching liquors of natural rhenium mineral and rhenium-containing spent wastes, in which ReO4 -is expected to be the dominant rhenium form. 3,13 In this regard, both solid-liquid extraction (SLE) and liquidliquid extraction (LLE) strategies are appealing.…”

Section: Introductionmentioning

confidence: 99%

Highly Selective Anion Recognition, Extraction and Deep Removal Using a Superphane

Zhou

2021

Preprint

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Highly selective anion recognition and extraction are critical and challenging to deep removal of pollutants from the environment and effective recovery of valuable chemicals from low–content (at sub–ppm or ppb level) sources. Herein, we detail the gram–scale synthesis of a superphane 2, a new supramolecular host that was found capable of encapsulating ReO4– with high selectivity, as suggested by the single–crystal structures, NMR spectroscopy and theoretical calculations. Under solid–liquid extraction condidtions, 2 proved able to extract perrhenate from the solid mixture containing trace ReO4– (as low as 200 ppb) with near 100% selectivity over other 7 competing anions. Under liquid–liquid extraction conditions, using 2 as the supramolecular extractant, over 99.99% of ReO4– could be separated from the complex simulated aqueous waste streams containing ppm–level perrhenate and large excess of competing ions. Notably, after extraction, 2 could be recycled and reused by simple treatment with NaHCO3. This study opens up the door to development of superphane–based advanced materials for deep elimination of pollutants from the envirenment and purification of chemicals of interest with high efficiency and selectivity.

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“…Based on this assumption, in the 1990s, separation of Tc through ion exchange was part of the Hanford tank waste pretreatment flowsheet . However, while effective separation of Tc (as TcO 4 – ) from the simulated solutions and some Hanford wastes could be achieved, the method failed for waste samples containing high concentrations of organics, with only a fraction of the total soluble Tc being separated. − This unexpected Tc behavior was found to persist for several different tank waste samples. Further, in control experiments where 95m/99m TcO 4 – was added to the tank waste samples containing native 99 Tc and passed through TcO 4 – -selective resins such as Reillex HPQ, ABEC, or SuperLig 639 to test retention, the spiked samples exhibited expected 95m/99m TcO 4 – retention unlike the native samples. ,,, A plausible explanation is the existence of tank waste Tc as low-valent forms in addition to TcO 4 – .…”

Section: Introductionmentioning

confidence: 99%

Identification and Quantification of Technetium Species in Hanford Waste Tank AN-102

et al. 2020

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Technetium-99 (Tc), a high yield fission product generated in nuclear reactors, is one of the most difficult contaminants to address at the U.S. Department of Energy Hanford, Savannah River, and other sites. In strongly alkaline solutions typifying Hanford tank waste, Tc exists as pertechnetate (TcO 4 − ) (oxidation state VII) as well as in reduced forms (oxidation state < VII), collectively known as nonpertechnetate (non-TcO 4 − ) species. Designing strategies for effective Tc management, including separation and immobilization, necessitates understanding the molecular structure of the non-TcO 4 − species and their identification in actual tank waste samples. Identification of non-TcO 4 − species would facilitate the development of new treatment technologies effective for dissimilar Tc species. Toward this objective, a spectroscopic library of the Tc(I) [fac-Tc(CO) 3 ] + and Tc(II, IV, V, VII) compounds was generated and applied to the characterization of the actual Hanford AN-102 tank waste supernatant, which was processed to adjust Na concentration to ∼5.6 M and remove 137 Cs by spherical resorcinol-formaldehyde (sRF) ion-exchange resin. Post 137 Cs removal, the cesium-loaded sRF column was eluted with 0.45 M HNO 3 . As-received AN-102, Cs-depleted effluent, and sRF eluate fractions were comprehensively characterized for chemical composition and speciation of Tc using 99 Tc nuclear magnetic resonance spectroscopy and X-ray absorption spectroscopy. It was demonstrated for the first time that non-TcO 4 − Tc present in the AN-102 tank waste is composed of several low-valent Tc species, including the Tc(I) [fac-Tc(CO) 3 ] + and Tc(IV) compounds. This is the first demonstration of multiple non-TcO 4 − species co-existing in the Hanford tank waste, highlighting their importance for the waste processing.

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Multiple Ion Exchange Column Tests for Technetium Removal from Hanford Site Tank 241‐AW‐101 with Superlig^®639 Resin

Cited by 13 publications

References 20 publications

Protocol for Identifying the Presence of and Understanding the Nature of Soluble, Non-pertechnetate Technetium in Hanford Tank Supernatants

Protocol for Identifying the Presence of and Understanding the Nature of Soluble, Non-pertechnetate Technetium in Hanford Tank Supernatants

Highly Selective Anion Recognition, Extraction and Deep Removal Using a Superphane

Identification and Quantification of Technetium Species in Hanford Waste Tank AN-102

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Multiple Ion Exchange Column Tests for Technetium Removal from Hanford Site Tank 241‐AW‐101 with Superlig®639 Resin

Cited by 13 publications

References 20 publications

Protocol for Identifying the Presence of and Understanding the Nature of Soluble, Non-pertechnetate Technetium in Hanford Tank Supernatants

Protocol for Identifying the Presence of and Understanding the Nature of Soluble, Non-pertechnetate Technetium in Hanford Tank Supernatants

Highly Selective Anion Recognition, Extraction and Deep Removal Using a Superphane

Identification and Quantification of Technetium Species in Hanford Waste Tank AN-102

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Product

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Multiple Ion Exchange Column Tests for Technetium Removal from Hanford Site Tank 241‐AW‐101 with Superlig^®639 Resin