Structure and Reactivity of X-ray Amorphous Uranyl Peroxide, U2O7

Samuel O. Odoh; Jacob Shamblin; Christopher A. Colla; Sarah Hickam; Haylie L. Lobeck; Rachel A K Lopez; Travis Olds; Jennifer E S Szymanowski; Ginger E. Sigmon; Joerg Neuefeind; William H. Casey; Maik Lang; Laura Gagliardi; Peter C. Burns

doi:10.1021/acs.inorgchem.6b00017

Structure and Reactivity of X-ray Amorphous Uranyl Peroxide, U₂O₇

Samuel O. Odoh, Jacob Shamblin, Christopher A. Colla, Sarah Hickam, Haylie L. Lobeck, Rachel A K Lopez, Travis Olds, Jennifer E S Szymanowski, Ginger E. Sigmon, Joerg Neuefeind, William H. Casey, Maik Lang, Laura Gagliardi, Peter C. Burns

Chemistry (Twin Cities)

Research output: Contribution to journal › Article › peer-review

48 Scopus citations

Abstract

Recent accidents resulting in worker injury and radioactive contamination occurred due to pressurization of uranium yellowcake drums produced in the western U.S.A. The drums contained an X-ray amorphous reactive form of uranium oxide that may have contributed to the pressurization. Heating hydrated uranyl peroxides produced during in situ mining can produce an amorphous compound, as shown by X-ray powder diffraction of material from impacted drums. Subsequently, studtite, [(UO₂)(O₂)(H₂O)₂](H₂O)₂, was heated in the laboratory. Its thermal decomposition produced a hygroscopic anhydrous uranyl peroxide that reacts with water to release O₂ gas and form metaschoepite, a uranyl-oxide hydrate. Quantum chemical calculations indicate that the most stable U₂O₇ conformer consists of two bent (UO₂)²⁺ uranyl ions bridged by a peroxide group bidentate and parallel to each uranyl ion, and a μ₂-O atom, resulting in charge neutrality. A pair distribution function from neutron total scattering supports this structural model, as do ¹H- and ¹⁷O-nuclear magnetic resonance spectra. The reactivity of U₂O₇ in water and with water in air is higher than that of other uranium oxides, and this can be both hazardous and potentially advantageous in the nuclear fuel cycle.

Original language	English (US)
Pages (from-to)	3541-3546
Number of pages	6
Journal	Inorganic chemistry
Volume	55
Issue number	7
DOIs	https://doi.org/10.1021/acs.inorgchem.6b00017
State	Published - Apr 18 2016

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Publisher Copyright:
© 2016 American Chemical Society.

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10.1021/acs.inorgchem.6b00017

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@article{875533136cdf471cbec6ff27911d7e91,

title = "Structure and Reactivity of X-ray Amorphous Uranyl Peroxide, U2O7",

abstract = "Recent accidents resulting in worker injury and radioactive contamination occurred due to pressurization of uranium yellowcake drums produced in the western U.S.A. The drums contained an X-ray amorphous reactive form of uranium oxide that may have contributed to the pressurization. Heating hydrated uranyl peroxides produced during in situ mining can produce an amorphous compound, as shown by X-ray powder diffraction of material from impacted drums. Subsequently, studtite, [(UO2)(O2)(H2O)2](H2O)2, was heated in the laboratory. Its thermal decomposition produced a hygroscopic anhydrous uranyl peroxide that reacts with water to release O2 gas and form metaschoepite, a uranyl-oxide hydrate. Quantum chemical calculations indicate that the most stable U2O7 conformer consists of two bent (UO2)2+ uranyl ions bridged by a peroxide group bidentate and parallel to each uranyl ion, and a μ2-O atom, resulting in charge neutrality. A pair distribution function from neutron total scattering supports this structural model, as do 1H- and 17O-nuclear magnetic resonance spectra. The reactivity of U2O7 in water and with water in air is higher than that of other uranium oxides, and this can be both hazardous and potentially advantageous in the nuclear fuel cycle.",

author = "Odoh, {Samuel O.} and Jacob Shamblin and Colla, {Christopher A.} and Sarah Hickam and Lobeck, {Haylie L.} and Lopez, {Rachel A K} and Travis Olds and Szymanowski, {Jennifer E S} and Sigmon, {Ginger E.} and Joerg Neuefeind and Casey, {William H.} and Maik Lang and Laura Gagliardi and Burns, {Peter C.}",

note = "Publisher Copyright: {\textcopyright} 2016 American Chemical Society.",

year = "2016",

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doi = "10.1021/acs.inorgchem.6b00017",

language = "English (US)",

volume = "55",

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T1 - Structure and Reactivity of X-ray Amorphous Uranyl Peroxide, U2O7

AU - Odoh, Samuel O.

AU - Shamblin, Jacob

AU - Colla, Christopher A.

AU - Hickam, Sarah

AU - Lobeck, Haylie L.

AU - Lopez, Rachel A K

AU - Olds, Travis

AU - Szymanowski, Jennifer E S

AU - Sigmon, Ginger E.

AU - Neuefeind, Joerg

AU - Casey, William H.

AU - Lang, Maik

AU - Gagliardi, Laura

AU - Burns, Peter C.

PY - 2016/4/18

Y1 - 2016/4/18

N2 - Recent accidents resulting in worker injury and radioactive contamination occurred due to pressurization of uranium yellowcake drums produced in the western U.S.A. The drums contained an X-ray amorphous reactive form of uranium oxide that may have contributed to the pressurization. Heating hydrated uranyl peroxides produced during in situ mining can produce an amorphous compound, as shown by X-ray powder diffraction of material from impacted drums. Subsequently, studtite, [(UO2)(O2)(H2O)2](H2O)2, was heated in the laboratory. Its thermal decomposition produced a hygroscopic anhydrous uranyl peroxide that reacts with water to release O2 gas and form metaschoepite, a uranyl-oxide hydrate. Quantum chemical calculations indicate that the most stable U2O7 conformer consists of two bent (UO2)2+ uranyl ions bridged by a peroxide group bidentate and parallel to each uranyl ion, and a μ2-O atom, resulting in charge neutrality. A pair distribution function from neutron total scattering supports this structural model, as do 1H- and 17O-nuclear magnetic resonance spectra. The reactivity of U2O7 in water and with water in air is higher than that of other uranium oxides, and this can be both hazardous and potentially advantageous in the nuclear fuel cycle.

AB - Recent accidents resulting in worker injury and radioactive contamination occurred due to pressurization of uranium yellowcake drums produced in the western U.S.A. The drums contained an X-ray amorphous reactive form of uranium oxide that may have contributed to the pressurization. Heating hydrated uranyl peroxides produced during in situ mining can produce an amorphous compound, as shown by X-ray powder diffraction of material from impacted drums. Subsequently, studtite, [(UO2)(O2)(H2O)2](H2O)2, was heated in the laboratory. Its thermal decomposition produced a hygroscopic anhydrous uranyl peroxide that reacts with water to release O2 gas and form metaschoepite, a uranyl-oxide hydrate. Quantum chemical calculations indicate that the most stable U2O7 conformer consists of two bent (UO2)2+ uranyl ions bridged by a peroxide group bidentate and parallel to each uranyl ion, and a μ2-O atom, resulting in charge neutrality. A pair distribution function from neutron total scattering supports this structural model, as do 1H- and 17O-nuclear magnetic resonance spectra. The reactivity of U2O7 in water and with water in air is higher than that of other uranium oxides, and this can be both hazardous and potentially advantageous in the nuclear fuel cycle.

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