Synthesis of Organically Templated Nanoporous Tin(II/IV) Phosphate for Radionuclide and Metal Sequestration

Dm, Wellman; Sv, Mattigod; Ke, Parker; Sm, Heald; C, Wang; Ge, Fryxell

doi:10.1021/ic068003l

Cited by 13 publications

(16 citation statements)

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“…One approach employs Fe II for reduction of TcO 4 – and stabilization within the iron oxide, iron phosphate matrix, , or clay matrix . Another approach employs Sn II incorporated into aluminophosphate nanocomposites for the reduction of TcO 4 – followed by stabilization within the nanocomposite , . Other approaches use sulfides or iron sulfides for reduction of TcO 4 – and subsequent sequestration of the resulting low valent Tc species …”

Section: Introductionmentioning

confidence: 99%

Strategies for the Photoreduction of Tc‐99 Pertechnetate to Low‐Valent Tc by Keggin Polyoxometalates

et al. 2020

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Technetium‐99 (half‐life of 2.1 × 105 yrs, βmax = 0.29 MeV) is a hazardous radiological contaminant, which, in its predominant form of pertechnetate (TcO4–), is highly mobile in the environment. Most strategies for the removal of pertechnetate from the environment involve uptake and/or absorption of pertechnetate using resins, clays, cationic metal‐organic frameworks and even thorium borate ceramic like materials. Alternative approaches have involved the reduction and subsequent sequestration of lower valent technetium species using iron, sulfides, or iron sulfides. Our lab has explored this strategy using the lacunary alpha‐2 Wells–Dawson polyoxometalate (α2‐[P2W17O61]10–) to both reduce and sequester lower valent technetium, and we have reported on the ligand features that stabilize the reduced species. In this work we investigate the potential of “plenary” Keggin POMs (XW12O40n–) (X = P, Si, Al, n = 3, 4, 5, respectively) to both reduce TcO4– and stabilize the reduced Tc species. Specifically, we report on the mechanism by which the reduction of technetium occurs and find that PW12, SiW12, and AlW12 promote the reduction of TcO4– to lower valent states. X‐ray absorption spectroscopy was used to confirm a combination of TcIV {in the form of TcO2·2H2O and Tc2(µ‐O)24+} and TcV, which is subsequently complexed into a POM defect as a TcV=O species.

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Section: Introductionmentioning

confidence: 99%

Strategies for the Photoreduction of Tc‐99 Pertechnetate to Low‐Valent Tc by Keggin Polyoxometalates

et al. 2020

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“…A Sb-SnO2 material was reported in near neutral ionic strength systems to give Tc distribution coefficients, Kd (in mL/g), of 1 × 10 6 mL/g; [35] nanoiron on commercially available silicone in a DIW system gave a Tc Kd of 8100 mL/g; [36] Purolite A5320E resin in a near neutral groundwater brine measured a Tc Kd of 1.2 × 10 3 mL/g; [14] nanoporous Sn-phosporous measured a Tc Kd of 9×10 4 mL/g; [37] activated carbon 824 BC in artificial groundwater gave a Tc Kd of 120 mL/g; [18] calcium apatite in artificial groundwater measured a Tc Kd of 223 mL/g; [18] granual activated carbon in different groundwater gave a Tc Kd of 2.4 ×10 4 mL/g; [38] a macroporous poly(GMA-co-EGDMA) polymer in near neutral solutions measured a Tc Kd of 2.3 ×10 3 mL/g. [39] In comparison, the Sn-A in DIW in this study measured a Tc Kd of 3.7 × 10 7 mL/g confirming its strong performance as a Tc removal material from near neutral, low ionic strength environments.…”

Section: Discussionmentioning

confidence: 99%

The function of Sn(II)-apatite as a Tc immobilizing agent

Asmussen

Neeway

Lawter

et al. 2016

Journal of Nuclear Materials

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At the U.S. Department of Energy Hanford Site, Tc-99 is a component of lowactivity waste (LAW) fractions of the nuclear tank waste and removal of Tc from LAW streams would greatly benefit the site remediation process. In this study, we investigated the removal of Tc(VII), as pertechnetate, from deionized water (DIW) and a LAW simulant through batch sorption testing and solid phase characterization using tin (II) apatite (Sn-A) and SnCl2. Sn-A showed higher levels of Tc removal from both DIW and LAW simulant. Scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/XEDS) and X-ray absorption spectroscopy (XAS) of reacted Sn-A in DIW showed that TcO4-is reduced to Tc(IV) on the Sn-A surface. The performance of Sn-A in the LAW simulant was lowered due to a combined effect of the high alkalinity, which lead to an increased dissolution of Sn from the Sn-A, and a preference for the reduction of Cr(VI).

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“…These differences indicate that the adsorption performance of the Cu-EDA functional monolayer is dependent on the type of substrate to which it is attached. Scoping tests conducted on Sn(II)-bearing nanoporous phosphates in dilute NaHCO 3 solution indicated K d values exceeding 90 000 mL/g (Wellman et al 2006). However, more extensive tests are needed to fully evaluate the 99 Tc getter potential of these novel synthetic materials.…”

Section: Novel Synthetic Gettersmentioning

confidence: 98%

“…Metallic copper and its oxides (Haq et al 1980), soils and soil minerals (Rancon 1988), cementitious forms (Atkins and Glasser 1990), various types of minerals (Couture and Seitz 1983, Fetter et al 1996, Gradev 1987, Kang et al 1999, Krumhansl 2003, Taylor 1990), organophilic clays (Bors et al 1994a), modified montmorillonites (Sazarashi et al 1995), and novel adsorbents (Kaplan et al 2000 have been tested and evaluated for their getter properties for radioiodine. A similar effort was conducted to identify suitable getters for 99 Tc (Balsley et al 1985, Balsley et al 1996, Balsley et al 1997, Byegard et al 1992, Cui and Eriksen 1996b, Ito and Kanno 1988, Kang et al 1999, Kang et al 1996, Krumhansl 2003, Kunze et al 1996, Liang et al 1996, Lieser and Bauscher, 1988, Moore 2003, Palmer and Meyer 1981, Strickert et al 1980, Viani 1999, Wellman et al 2006, Zhuang et al 1988). …”

Section: Gettersmentioning

confidence: 99%

Review of Potential Candidate Stabilization Technologies for Liquid and Solid Secondary Waste Streams

Pierce¹,

Mattigod²,

Westsik³

et al. 2010

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Executive SummaryPacific Northwest National Laboratory has initiated a waste-form testing program to support the longterm durability evaluation of a waste form for secondary wastes generated from the treatment and immobilization of Hanford radioactive tank wastes. The purpose of the work discussed in this report is to identify candidate stabilization technologies and getters that have the potential to successfully treat the secondary waste stream liquid effluent, mainly from off-gas scrubbers and spent solids, produced by the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Down-selection to the most promising stabilization processes/waste forms is needed to support the design of a solidification treatment unit (STU) to be added to the Effluent Treatment Facility (ETF). To support key decision processes, an initial screening of the secondary liquid waste forms must be completed by February 2010. Later, more comprehensive and longer term performance testing will be conducted, following the guidance provided by the secondary waste-form selection, development, and performance evaluation roadmap. The resulting waste form will be compliant to regulations and performance criteria and will lead to cost-effective disposal of the secondary wastes.This report starts with a brief review of some of the most commonly used solidification formulations that would be candidates for secondary liquid waste streams. In this review, the available data on performance are discussed, and some preliminary recommendations are provided for materials that should undergo additional screening testing. We also 1) discuss options for disposal of WTP secondary solid waste streams, 2) provide a brief overview of standard regulatory test methods used for measuring contaminant leachability and waste-form physical strength (with emphasis on the U.S. Environmental Protection Agency's [EPA's] new methods as a screening tool for comparing waste solidification materials of interest), and 3) provide an overview of factors that must be considered in long-term performance testing, including state-of-the-art characterization tools that can provide the data needed to technically defend predictive modeling simulations of long-term material behavior. The long-term wasteform testing and solid and leachate characterization must be robust enough to effectively predict material performance in the Integrated Disposal Facility over the 10,000-year period of performance for the engineered system. The solidification technologies for liquid waste streams include cement/grout, containerized Cast Stone, phosphate-bonded ceramics, alkali-aluminosilicate geopolymers, hydroceramics, L-TEM, and fluidized-bed steam reforming (FBSR). In addition to these, other mature technologies and two compounds, namely goethite and sodalite (that are still being developed), that show considerable promise as waste forms or getters are also discussed. It is our recommendation, based upon the available literature, that Cast Stone, chemically bonded phosphate ceramics (Ceramicrete...

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Synthesis of Organically Templated Nanoporous Tin(II/IV) Phosphate for Radionuclide and Metal Sequestration

Cited by 13 publications

References 0 publications

Strategies for the Photoreduction of Tc‐99 Pertechnetate to Low‐Valent Tc by Keggin Polyoxometalates

Strategies for the Photoreduction of Tc‐99 Pertechnetate to Low‐Valent Tc by Keggin Polyoxometalates

The function of Sn(II)-apatite as a Tc immobilizing agent

Review of Potential Candidate Stabilization Technologies for Liquid and Solid Secondary Waste Streams

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