Natrophosphate and kogarkoite precipitated from alkaline nuclear waste at Hanford

Bolling, Stacey D.; Reynolds, Jacob G.; Ely, Thomas M.; Lachut, James S.; LaMothe, Margaret E.; Cooke, Gary A.

doi:10.1007/s10967-019-06924-9

Cited by 10 publications

(8 citation statements)

References 34 publications

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“…The U.S. government currently spends approximately $6 billion annually on managing the legacy of the Cold War, including around 300 million liters of highly radioactive wastes stored in hundreds of tanks at the Hanford Site (WA), the Savannah River Site (SC), and the West Valley Nuclear Site (NY). − By far, the largest volumes reside at Hanford (177 tanks storing 200 million liters). − The wastes, which must be processed for disposal, are extremely complex mixtures of saltcakes, sludges, and highly alkaline solutions of concentrated electrolytes that have been exposed to ionizing radiation for many decades. ,,− Aluminum (Al) is a major component in the waste due to codisposal of Al fuel cladding and the addition of Al nitrate as a “salting agent”. ,,− To process these Hanford wastes, construction of the most expensive chemical plant in the world (>$10 billion, est.) is underway.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cr(III) Adsorption on the Dissolution of Boehmite Nanoparticles in Caustic Solution

Cui

Zhang

Pearce

et al. 2020

Environ. Sci. Technol.

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The incorporation of relatively minor impurity metals onto metal (oxy)hydroxides can strongly impact solubility. In complex highly alkaline multicomponent radioactive tank wastes such as those at the Hanford Nuclear Reservation, tests indicate that the surface area-normalized dissolution rate of boehmite (γ-AlOOH) nanomaterials is at least an order of magnitude lower than that predicted for the pure phase. Here, we examine the dissolution kinetics of boehmite coated by adsorbed Cr(III), which adheres at saturation coverages as sparse chemisorbed monolayer clusters. Using 40 nm boehmite nanoplates as a model system, temperature-dependent dissolution rates of pure versus Cr(III)adsorbed boehmite showed that the initial rate for the latter is consistently several times lower, with an apparent activation energy 16 kJ•mol −1 higher. Although the surface coverage is only around 50%, solution analysis coupled to multimethod solids characterization reveal a phyicochemical armoring effect by adsorbed Cr(III) that substantially reduces the number of dissolution-active sites on particle surfaces. Such findings could help improve kinetics models of boehmite and/or metal ion adsorbed boehmite nanomaterials, ultimately providing a stronger foundation for the development of more robust complex radioactive liquid waste processing strategies.

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Section: Introductionmentioning

confidence: 99%

Effect of Cr(III) Adsorption on the Dissolution of Boehmite Nanoparticles in Caustic Solution

Cui

Zhang

Pearce

et al. 2020

Environ. Sci. Technol.

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“…The quantity of each salt depends on the relative abundance of PO 4 3− , F − and sulfate (SO 4 2− ) in each waste tank. [21][22][23][24] Likewise, PO 4 3− are partitioned in solid phase salts between natrophosphate, sodium phosphate dodecahydrate (Na 3 PO 4 •0.25NaOH•12H 2 O) and nastrophite (NaSr(PO 4 )•9H 2 O). [24][25][26] Previous studies of the solubility of natrophosphate in multicomponent NaF : Na 3 PO 4 : H 2 O systems have suggested that the natrophosphate composition changes based on solution compositions and that the crystalline phase is a solid-solution.…”

Section: Introductionmentioning

confidence: 99%

“…16 Beyond the interest in fundamental chemistry of the disparate environments of Na + ions in this crystal structure, natrophosphate is of interest because it occurs in alkaline rocks, 14,[18][19][20] and is present in radioactive waste stored at the Hanford Site in Richland, WA, United States. [20][21][22][23] Natrophosphate is one of several fluoride or phosphate-containing salts found in the waste. The fluoride ions are partitioned in solid phase salts between natrophosphate, sodium fluoride (NaF) and kogarkoite (Na 3 FSO 4 ).…”

Section: Introductionmentioning

confidence: 99%

Sodium site occupancy and phosphate speciation in natrophosphate are invariant to changes in NaF and Na₃PO₄ concentration

Graham

Nienhuis

Reynolds

et al. 2022

Inorg. Chem. Front.

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“…Recently, the interest in natrophosphate has been renewed due to its findings as one of the major salts in alkaline nuclear wastes such as those stored at the Hanford site, near Richland, WA, USA [18][19][20][21]. The occurrence of this phase considerably complicates the waste processing, which necessitates detailed studies of its composition and solubility.…”

Section: Introductionmentioning

confidence: 99%

Natrophosphate, Arctic Mineral and Nuclear Waste Phase: Structure Refinements and Chemical Variability

2021

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The crystal structures of natural (Mt. Koashva, Khibiny alkaline massif, Kola Peninsula, Russian Arctic) and synthetic (obtained from an aqueous solution of sodium phosphate and sodium fluoride (1:1) by evaporation at room temperature (RT)) natrophosphate, Na7(PO4)2F·19H2O, have been investigated using single-crystal X-ray diffraction analysis. Natrophosphate and its synthetic analogue are cubic, Fd-3c, a = 27.6942(3) Å (natrophosphate at RT), a = 27.6241(4) Å (natrophosphate at 100 K), a = 28.1150(12) Å (synthetic analogue at RT), a = 27.9777(7) Å (synthetic analogue at 100 K). The crystal structure is based upon the super-octahedral [Na6(H2O)18F]5+ polycationic complexes consisting of six edge-linked Na6(OH2)5F octahedra sharing one common fluorine vertex. The A site is statistically occupied by Na and H2O with the prevalence of H2O with the refined occupancy factors O:Na equal to 0.53:0.47 for natrophosphate and 0.75:0.25 for its synthetic analogue. The coordination of the A site in synthetic natrophosphate is enlarged compared to the natural sample, which agrees well with its higher occupancy by H2O molecules. The general formula of natrophosphates can be written as Na6+xHxF(PO4)2·(19 + x)H2O, where x = 0–1. The chemical variability of natrophosphate allows to explain the discrepancies in its solubility reported by different authors. The information-based parameters of structural complexity are equal to 3.713 bit/atom and 2109.177 bit/cell that allows to classify natrophosphate as a structurally very complex mineral.

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Natrophosphate and kogarkoite precipitated from alkaline nuclear waste at Hanford

Cited by 10 publications

References 34 publications

Effect of Cr(III) Adsorption on the Dissolution of Boehmite Nanoparticles in Caustic Solution

Effect of Cr(III) Adsorption on the Dissolution of Boehmite Nanoparticles in Caustic Solution

Sodium site occupancy and phosphate speciation in natrophosphate are invariant to changes in NaF and Na₃PO₄ concentration

Natrophosphate, Arctic Mineral and Nuclear Waste Phase: Structure Refinements and Chemical Variability

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Natrophosphate and kogarkoite precipitated from alkaline nuclear waste at Hanford

Cited by 10 publications

References 34 publications

Effect of Cr(III) Adsorption on the Dissolution of Boehmite Nanoparticles in Caustic Solution

Effect of Cr(III) Adsorption on the Dissolution of Boehmite Nanoparticles in Caustic Solution

Sodium site occupancy and phosphate speciation in natrophosphate are invariant to changes in NaF and Na3PO4 concentration

Natrophosphate, Arctic Mineral and Nuclear Waste Phase: Structure Refinements and Chemical Variability

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Sodium site occupancy and phosphate speciation in natrophosphate are invariant to changes in NaF and Na₃PO₄ concentration