Impact of Cr and Co on 99Tc retention in magnetite: A combined study of ab initio molecular dynamics and experiments

Mal Soon Lee; Sarah A. Saslow; Wooyong Um; Dong Sang Kim; Albert A. Kruger; Roger Rousseau; Vassiliki Alexandra Glezakou

doi:10.1016/j.jhazmat.2019.121721

Impact of Cr and Co on ⁹⁹Tc retention in magnetite: A combined study of ab initio molecular dynamics and experiments

Mal Soon Lee, Sarah A. Saslow, Wooyong Um, Dong Sang Kim, Albert A. Kruger, Roger Rousseau, Vassiliki Alexandra Glezakou

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

4 Scopus citations

Abstract

The effect of co-mingled dopants, Co(II) and Cr(III), on Tc(IV) incorporation and retention in magnetite under varying temperatures (75–700 °C) was explored using ab initio molecular dynamics simulations, batch experiments, and solid phase characterization. Tc(IV) stabilization was achieved with a magnetite surface oversaturated with or containing an equal number of Tc and Cr. Under oversaturation conditions, the forced formation of a Cr₂O₃ phase on the magnetite surface may help prevent Tc release. Upon Co addition, and depending on the relative concentration of Tc, Cr, and Co at the magnetite surface, Co was found to preferentially stabilize Cr rather than Tc and suppress the formation of the protective Cr₂O₃ surface phase. Only systems with similar Cr/Co concentrations or relatively high Cr concentrations stabilized Tc within magnetite. As such, the relative concentration of Tc, Cr, and Co was identified as a critical parameter for maximizing dopant efficacy towards Tc stabilization in magnetite.

Original language	English
Article number	121721
Journal	Journal of Hazardous Materials
Volume	387
DOIs	https://doi.org/10.1016/j.jhazmat.2019.121721
State	Published - Apr 5 2020
Externally published	Yes

Funding

The authors would like to thank Steven Luksic for supporting the heat treatment of experimental samples and Ian Leavy for performing solid digests and measurements. M.-S. L. S. A. S. D.-S. K. and A. A. K. were supported by the U.S. Department of Energy's (DOE) Waste Treatment and Immobilization Plant Project of the Office of River Protection, and R.R. and V.-A. G. by the Office of Science, Office of Basic Energy Science, Division of Chemical Sciences, Geosciences and Biosciences. W. U. was also supported by the National Research Foundation of Korea funded by the Ministry of Education (NRF-2017M2B2B1072374 and NRF-2017M2B2B1072404). Computational resources were provided by PNNL's Research Computing facility and the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility operated under Contract No. DE-AC02-05CH11231. The XANES and EXAFS data collection used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. The authors would like to thank Steven Luksic for supporting the heat treatment of experimental samples and Ian Leavy for performing solid digests and measurements. M.-S. L., S. A. S., D.-S. K., and A. A. K. were supported by the U.S. Department of Energy’s (DOE) Waste Treatment and Immobilization Plant Project of the Office of River Protection , and R.R. and V.-A. G. by the Office of Science, Office of Basic Energy Science, Division of Chemical Sciences, Geosciences and Biosciences . W. U. was also supported by the National Research Foundation of Korea funded by the Ministry of Education ( NRF-2017M2B2B1072374 and NRF-2017M2B2B1072404 ). Computational resources were provided by PNNL’s Research Computing facility and the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility operated under Contract No. DE-AC02-05CH11231. The XANES and EXAFS data collection used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

Funders	Funder number
Office of River Protection
U.S. Department of Energy
Office of Science	DE-AC02-05CH11231
Office of Science
Basic Energy Sciences
Argonne National Laboratory	DE-AC02-06CH11357
Argonne National Laboratory
Chemical Sciences, Geosciences, and Biosciences Division
Ministry of Education	NRF-2017M2B2B1072374, NRF-2017M2B2B1072404
Ministry of Education
National Research Foundation of Korea

Keywords

Ab initio molecular dynamics
Dopant effect
Spinel
Tc retention
Temperature effects
X-ray absorption spectroscopy

Access to Document

10.1016/j.jhazmat.2019.121721

Cite this

@article{6367768b5ee44a66bf93a72a5687a414,

title = "Impact of Cr and Co on 99Tc retention in magnetite: A combined study of ab initio molecular dynamics and experiments",

abstract = "The effect of co-mingled dopants, Co(II) and Cr(III), on Tc(IV) incorporation and retention in magnetite under varying temperatures (75–700 °C) was explored using ab initio molecular dynamics simulations, batch experiments, and solid phase characterization. Tc(IV) stabilization was achieved with a magnetite surface oversaturated with or containing an equal number of Tc and Cr. Under oversaturation conditions, the forced formation of a Cr2O3 phase on the magnetite surface may help prevent Tc release. Upon Co addition, and depending on the relative concentration of Tc, Cr, and Co at the magnetite surface, Co was found to preferentially stabilize Cr rather than Tc and suppress the formation of the protective Cr2O3 surface phase. Only systems with similar Cr/Co concentrations or relatively high Cr concentrations stabilized Tc within magnetite. As such, the relative concentration of Tc, Cr, and Co was identified as a critical parameter for maximizing dopant efficacy towards Tc stabilization in magnetite.",

keywords = "Ab initio molecular dynamics, Dopant effect, Spinel, Tc retention, Temperature effects, X-ray absorption spectroscopy",

author = "Lee, {Mal Soon} and Saslow, {Sarah A.} and Wooyong Um and Kim, {Dong Sang} and Kruger, {Albert A.} and Roger Rousseau and Glezakou, {Vassiliki Alexandra}",

note = "Publisher Copyright: {\textcopyright} 2019",

year = "2020",

month = apr,

day = "5",

doi = "10.1016/j.jhazmat.2019.121721",

language = "English",

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T1 - Impact of Cr and Co on 99Tc retention in magnetite

T2 - A combined study of ab initio molecular dynamics and experiments

AU - Lee, Mal Soon

AU - Saslow, Sarah A.

AU - Um, Wooyong

AU - Kim, Dong Sang

AU - Kruger, Albert A.

AU - Rousseau, Roger

AU - Glezakou, Vassiliki Alexandra

PY - 2020/4/5

Y1 - 2020/4/5

N2 - The effect of co-mingled dopants, Co(II) and Cr(III), on Tc(IV) incorporation and retention in magnetite under varying temperatures (75–700 °C) was explored using ab initio molecular dynamics simulations, batch experiments, and solid phase characterization. Tc(IV) stabilization was achieved with a magnetite surface oversaturated with or containing an equal number of Tc and Cr. Under oversaturation conditions, the forced formation of a Cr2O3 phase on the magnetite surface may help prevent Tc release. Upon Co addition, and depending on the relative concentration of Tc, Cr, and Co at the magnetite surface, Co was found to preferentially stabilize Cr rather than Tc and suppress the formation of the protective Cr2O3 surface phase. Only systems with similar Cr/Co concentrations or relatively high Cr concentrations stabilized Tc within magnetite. As such, the relative concentration of Tc, Cr, and Co was identified as a critical parameter for maximizing dopant efficacy towards Tc stabilization in magnetite.

AB - The effect of co-mingled dopants, Co(II) and Cr(III), on Tc(IV) incorporation and retention in magnetite under varying temperatures (75–700 °C) was explored using ab initio molecular dynamics simulations, batch experiments, and solid phase characterization. Tc(IV) stabilization was achieved with a magnetite surface oversaturated with or containing an equal number of Tc and Cr. Under oversaturation conditions, the forced formation of a Cr2O3 phase on the magnetite surface may help prevent Tc release. Upon Co addition, and depending on the relative concentration of Tc, Cr, and Co at the magnetite surface, Co was found to preferentially stabilize Cr rather than Tc and suppress the formation of the protective Cr2O3 surface phase. Only systems with similar Cr/Co concentrations or relatively high Cr concentrations stabilized Tc within magnetite. As such, the relative concentration of Tc, Cr, and Co was identified as a critical parameter for maximizing dopant efficacy towards Tc stabilization in magnetite.

KW - Ab initio molecular dynamics

KW - Dopant effect

KW - Spinel

KW - Tc retention

KW - Temperature effects

KW - X-ray absorption spectroscopy

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