Kinetics of Uranyl Peroxide Nanocluster (U60) Sorption to Goethite

Luke R. Sadergaski; Amy E. Hixon

doi:10.1021/acs.est.8b02716

Kinetics of Uranyl Peroxide Nanocluster (U₆₀) Sorption to Goethite

Luke R. Sadergaski, Amy E. Hixon

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

9 Scopus citations

Abstract

The unique properties of uranium-based nanomaterials may significantly impact our current understanding of the fate and transport of U(VI) in environmental systems. Sorption of the uranyl peroxide nanocluster [(UO₂)(O₂)(OH)]₆₀ ^60- (U₆₀) to goethite (α-FeOOH) was studied using batch sorption experiments as a function of U₆₀ concentration (0.5-2 g·L^-1), mineral concentration (100-500 m²·L^-1), and pH (8-10). The resulting rate law describing U₆₀ interactions with goethite at pH 9 was R = ?k_rxn[U₆₀]^0.29±0.02[goethite]^1.2±0.1 where k_rxn = (6.7 ± 2.0) × 10^-4 (g·L^-1)^0.71±0.02(m²·L^-1)^?1.2±0.1(day^-1). The largest fraction of U₆₀ removed from solution was at pH 8, which is below the isoelectric point of the goethite used in this study. Site density calculations suggest that U₆₀ may exist on the goethite surface at a center-to-center distance of 5.4-6.5 nm, depending upon pH, which mirrors the center-to-center distance observed in the aqueous phase near the U₆₀ solubility limit. At pH 10, approximately 20% uranium was desorbed within 3 days. Analysis of the reacted mineral surface using X-ray photoelectron spectroscopy confirmed the presence of a single U(VI) species on the mineral surface, and electrospray ionization mass spectrometry revealed that U₆₀ remains intact during the sorption and desorption processes. These results demonstrate that the behavior of U₆₀ at the goethite-water interface is similar to that of discrete U(VI) but is governed by different sorption mechanisms and reaction kinetics, which has the potential to alter our current understanding of the fate and transport of uranium species in the environment.

Original language	English
Pages (from-to)	9818-9826
Number of pages	9
Journal	Environmental Science and Technology
Volume	52
Issue number	17
DOIs	https://doi.org/10.1021/acs.est.8b02716
State	Published - Sep 4 2018
Externally published	Yes

Funding

The authors thank Mr. Samuel N. Perry for assistance with Crystal Maker. The following centers and facilities t the University of Notre Dame provided access to instrumentation used in this research study: the Center for Environmental Science and Technology (BET, ICP-OES, zeta potential), the Mass Spectrometry and Proteomics Facility (ESI-MS), and the Center for Sustainable Energy's Materials Characterization Facility (pXRD, Raman, XPS). This material is based on work supported as part of the Materials Science of Actinides, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under award number DE-SC0001089. The authors thank Mr. Samuel N. Perry for assistance with CrystalMaker. The following centers and facilities at the University of Notre Dame provided access to instrumentation used in this research study: the Center for Environmental Science and Technology (BET, ICP-OES, zeta potential), the Mass Spectrometry and Proteomics Facility (ESI-MS), and the Center for Sustainable Energy’s Materials Characterization Facility (pXRD, Raman, XPS). This material is based on work supported as part of the Materials Science of Actinides, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under award number DE-SC0001089.

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10.1021/acs.est.8b02716

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title = "Kinetics of Uranyl Peroxide Nanocluster (U60) Sorption to Goethite",

abstract = "The unique properties of uranium-based nanomaterials may significantly impact our current understanding of the fate and transport of U(VI) in environmental systems. Sorption of the uranyl peroxide nanocluster [(UO2)(O2)(OH)]60 60- (U60) to goethite (α-FeOOH) was studied using batch sorption experiments as a function of U60 concentration (0.5-2 g·L-1), mineral concentration (100-500 m2·L-1), and pH (8-10). The resulting rate law describing U60 interactions with goethite at pH 9 was R = ?krxn[U60]0.29±0.02[goethite]1.2±0.1 where krxn = (6.7 ± 2.0) × 10-4 (g·L-1)0.71±0.02(m2·L-1)?1.2±0.1(day-1). The largest fraction of U60 removed from solution was at pH 8, which is below the isoelectric point of the goethite used in this study. Site density calculations suggest that U60 may exist on the goethite surface at a center-to-center distance of 5.4-6.5 nm, depending upon pH, which mirrors the center-to-center distance observed in the aqueous phase near the U60 solubility limit. At pH 10, approximately 20% uranium was desorbed within 3 days. Analysis of the reacted mineral surface using X-ray photoelectron spectroscopy confirmed the presence of a single U(VI) species on the mineral surface, and electrospray ionization mass spectrometry revealed that U60 remains intact during the sorption and desorption processes. These results demonstrate that the behavior of U60 at the goethite-water interface is similar to that of discrete U(VI) but is governed by different sorption mechanisms and reaction kinetics, which has the potential to alter our current understanding of the fate and transport of uranium species in the environment.",

author = "Sadergaski, {Luke R.} and Hixon, {Amy E.}",

note = "Publisher Copyright: {\textcopyright} 2018 American Chemical Society.",

year = "2018",

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doi = "10.1021/acs.est.8b02716",

language = "English",

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AU - Hixon, Amy E.

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N2 - The unique properties of uranium-based nanomaterials may significantly impact our current understanding of the fate and transport of U(VI) in environmental systems. Sorption of the uranyl peroxide nanocluster [(UO2)(O2)(OH)]60 60- (U60) to goethite (α-FeOOH) was studied using batch sorption experiments as a function of U60 concentration (0.5-2 g·L-1), mineral concentration (100-500 m2·L-1), and pH (8-10). The resulting rate law describing U60 interactions with goethite at pH 9 was R = ?krxn[U60]0.29±0.02[goethite]1.2±0.1 where krxn = (6.7 ± 2.0) × 10-4 (g·L-1)0.71±0.02(m2·L-1)?1.2±0.1(day-1). The largest fraction of U60 removed from solution was at pH 8, which is below the isoelectric point of the goethite used in this study. Site density calculations suggest that U60 may exist on the goethite surface at a center-to-center distance of 5.4-6.5 nm, depending upon pH, which mirrors the center-to-center distance observed in the aqueous phase near the U60 solubility limit. At pH 10, approximately 20% uranium was desorbed within 3 days. Analysis of the reacted mineral surface using X-ray photoelectron spectroscopy confirmed the presence of a single U(VI) species on the mineral surface, and electrospray ionization mass spectrometry revealed that U60 remains intact during the sorption and desorption processes. These results demonstrate that the behavior of U60 at the goethite-water interface is similar to that of discrete U(VI) but is governed by different sorption mechanisms and reaction kinetics, which has the potential to alter our current understanding of the fate and transport of uranium species in the environment.

AB - The unique properties of uranium-based nanomaterials may significantly impact our current understanding of the fate and transport of U(VI) in environmental systems. Sorption of the uranyl peroxide nanocluster [(UO2)(O2)(OH)]60 60- (U60) to goethite (α-FeOOH) was studied using batch sorption experiments as a function of U60 concentration (0.5-2 g·L-1), mineral concentration (100-500 m2·L-1), and pH (8-10). The resulting rate law describing U60 interactions with goethite at pH 9 was R = ?krxn[U60]0.29±0.02[goethite]1.2±0.1 where krxn = (6.7 ± 2.0) × 10-4 (g·L-1)0.71±0.02(m2·L-1)?1.2±0.1(day-1). The largest fraction of U60 removed from solution was at pH 8, which is below the isoelectric point of the goethite used in this study. Site density calculations suggest that U60 may exist on the goethite surface at a center-to-center distance of 5.4-6.5 nm, depending upon pH, which mirrors the center-to-center distance observed in the aqueous phase near the U60 solubility limit. At pH 10, approximately 20% uranium was desorbed within 3 days. Analysis of the reacted mineral surface using X-ray photoelectron spectroscopy confirmed the presence of a single U(VI) species on the mineral surface, and electrospray ionization mass spectrometry revealed that U60 remains intact during the sorption and desorption processes. These results demonstrate that the behavior of U60 at the goethite-water interface is similar to that of discrete U(VI) but is governed by different sorption mechanisms and reaction kinetics, which has the potential to alter our current understanding of the fate and transport of uranium species in the environment.

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SN - 0013-936X

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EP - 9826

JO - Environmental Science and Technology

JF - Environmental Science and Technology

IS - 17

ER -

Kinetics of Uranyl Peroxide Nanocluster (U₆₀) Sorption to Goethite

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