Dataset Information

⁹⁹TcO₄^- removal from legacy defense nuclear waste by an alkaline-stable 2D cationic metal organic framework.

ABSTRACT: Removal of ⁹⁹TcO₄^- from legacy defense nuclear tank waste at Savannah River Site is highly desirable for the purpose of nuclear safety and environmental protection, but currently not achievable given the extreme conditions including high alkalinity, high ionic strength, and strong radiation field. Herein, we present a potential solution to this long-term issue by developing a two-dimensional cationic metal organic framework SCU-103, showing ultrahigh stability in alkaline aqueous media and great resistance to both ? and ? radiation. More importantly, it is very effective for ⁹⁹TcO₄^- separation from aqueous media as demonstrated by fast exchange kinetics, high sorption capacity, and superior selectivity, leading to the successful removal of ⁹⁹TcO₄^- from actual Savannah River Site high level tank waste for the first time, to the best of our knowledge. In addition, the uptake mechanism is comprehensively elucidated by molecular dynamics simulation and density functional theory calculation, showing a unique chemical recognition of anions with low charge density.

SUBMITTER: Shen N

PROVIDER: S-EPMC7642432 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature

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99TcO4- removal from legacy defense nuclear waste by an alkaline-stable 2D cationic metal organic framework.

Shen Nannan N Yang Zaixing Z Liu Shengtang S Dai Xing X Xiao Chengliang C Taylor-Pashow Kathryn K Li Dien D Yang Chuang C Li Jie J Zhang Yugang Y Zhang Mingxing M Zhou Ruhong R Chai Zhifang Z Wang Shuao S

Nature communications 20201104 1

Removal of 99TcO4- from legacy defense nuclear tank waste at Savannah River Site is highly desirable for the purpose of nuclear safety and environmental protection, but currently not achievable given the extreme conditions including high alkalinity, high ionic strength, and strong radiation field. Herein, we present a potential solution to this long-term issue by developing a two-dimensional cationic metal organic framework SCU-103, showing ultrahigh stability in ...[more]

PMID: 33149147

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Project description:99Tc is one of the most problematic fission products in the nuclear fuel cycle owing to its large inventory in used nuclear fuel, long half-life, potential radiation hazard, high environmental mobility of its major species 99TcO4 -, and its redox-active nature. Ideally, 99TcO4 - should be removed at the first stage, when the used fuel rods are dissolved in highly concentrated nitric acid solution, which can substantially reduce its interference with the solvent extraction process through catalytic redox reactions with the key actinides and diminish the chance of discharge into the environment as the volatile species during the waste vitrification process. However, this task cannot be achieved by any of the reported anion-scavenging materials including traditional polymeric anion-exchange resins, inorganic cationic framework materials, and recently developed cationic metal-organic framework materials, because they either are not stable under the extreme conditions of the combined high acidity and strong radiation field or do not possess the required uptake selectivity towards 99TcO4 - in the presence of a huge excess of competing anions such as NO3 - and SO4 2-. Herein, we present the first study of 99TcO4 - removal under extreme conditions by a two-dimensional conjugated cationic covalent organic framework material, SCU-COF-1. This material exhibits ultrahigh acid stability, great resistance towards both large-dose β and γ irradiation and unprecedented 99TcO4 - uptake capabilities including extremely fast sorption kinetics (sorption equilibrium can be reached within 1 min), ultrahigh uptake capacity (702.4 mg g-1 for the surrogate ReO4 - at a slightly elevated temperature), and good anion-exchange selectivity towards 99TcO4 -. These excellent features endow SCU-COF-1 with the practical capabilities of separating 99TcO4 - from both simulant highly acidic fuel reprocessing solutions (3 M nitric acid) and low-activity waste streams at the US legacy nuclear site. The anion-exchange mechanism and the 99TcO4 - uptake selectivity are further demonstrated and clearly visualized by the molecular dynamics simulation investigations.

Dataset Information

⁹⁹TcO₄^- removal from legacy defense nuclear waste by an alkaline-stable 2D cationic metal organic framework.

Publications

<sup>99</sup>TcO<sub>4</sub><sup>-</sup> removal from legacy defense nuclear waste by an alkaline-stable 2D cationic metal organic framework.

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