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Title: Synthesis and characterization of redox-active ferric nontronite

Abstract

Heterogeneous redox reactions on clay mineral surfaces control mobility and bioavailability of redox-sensitive nutrients and contaminants. Iron (Fe) residing in clay mineral structures can either catalyze or directly participate in redox reactions; however, chemical controls over its reactivity are not fully understood. In our previous work we demonstrated that converting a minor portion of Fe(III) to Fe(II) (partial reduction) in the octahedral sheet of natural Fe-rich clay mineral nontronite (NAu-1) activates its surface, making it redox-active. In this study we produced and characterized synthetic ferric nontronite (SIP), highlighting structural and chemical similarities and differences between this synthetic nontronite and its natural counterpart NAu-1, and probed whether mineral surface is redox-active by reacting it with arsenic As(III) under oxic and anoxic conditions. We demonstrate that synthetic nontronite SIP undergoes the same activation as natural nontronite NAu-1 following the partial reduction treatment. Similar to NAu-1, SIP oxidized As(III) to As(V) under both oxic (catalytic pathway) and anoxic (direct oxidation) conditions. The similar reactivity trends observed for synthetic nontronite and its natural counterpart make SIP an appropriate analog for laboratory studies. The development of chemically pure analogs for ubiquitous soil minerals will allow for systematic research of the fundamental properties of these minerals.

Authors:
ORCiD logo; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1406702
Report Number(s):
PNNL-SA-124893
Journal ID: ISSN 0009-2541; 48563; 48820; KP1704020
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Chemical Geology; Journal Volume: 470; Journal Issue: C
Country of Publication:
United States
Language:
English
Subject:
Environmental Molecular Sciences Laboratory

Citation Formats

Ilgen, A. G., Kukkadapu, R. K., Dunphy, D. R., Artyushkova, K., Cerrato, J. M., Kruichak, J. N., Janish, M. T., Sun, C. J., Argo, J. M., and Washington, R. E. Synthesis and characterization of redox-active ferric nontronite. United States: N. p., 2017. Web. doi:10.1016/j.chemgeo.2017.07.010.
Ilgen, A. G., Kukkadapu, R. K., Dunphy, D. R., Artyushkova, K., Cerrato, J. M., Kruichak, J. N., Janish, M. T., Sun, C. J., Argo, J. M., & Washington, R. E. Synthesis and characterization of redox-active ferric nontronite. United States. doi:10.1016/j.chemgeo.2017.07.010.
Ilgen, A. G., Kukkadapu, R. K., Dunphy, D. R., Artyushkova, K., Cerrato, J. M., Kruichak, J. N., Janish, M. T., Sun, C. J., Argo, J. M., and Washington, R. E. Sun . "Synthesis and characterization of redox-active ferric nontronite". United States. doi:10.1016/j.chemgeo.2017.07.010.
@article{osti_1406702,
title = {Synthesis and characterization of redox-active ferric nontronite},
author = {Ilgen, A. G. and Kukkadapu, R. K. and Dunphy, D. R. and Artyushkova, K. and Cerrato, J. M. and Kruichak, J. N. and Janish, M. T. and Sun, C. J. and Argo, J. M. and Washington, R. E.},
abstractNote = {Heterogeneous redox reactions on clay mineral surfaces control mobility and bioavailability of redox-sensitive nutrients and contaminants. Iron (Fe) residing in clay mineral structures can either catalyze or directly participate in redox reactions; however, chemical controls over its reactivity are not fully understood. In our previous work we demonstrated that converting a minor portion of Fe(III) to Fe(II) (partial reduction) in the octahedral sheet of natural Fe-rich clay mineral nontronite (NAu-1) activates its surface, making it redox-active. In this study we produced and characterized synthetic ferric nontronite (SIP), highlighting structural and chemical similarities and differences between this synthetic nontronite and its natural counterpart NAu-1, and probed whether mineral surface is redox-active by reacting it with arsenic As(III) under oxic and anoxic conditions. We demonstrate that synthetic nontronite SIP undergoes the same activation as natural nontronite NAu-1 following the partial reduction treatment. Similar to NAu-1, SIP oxidized As(III) to As(V) under both oxic (catalytic pathway) and anoxic (direct oxidation) conditions. The similar reactivity trends observed for synthetic nontronite and its natural counterpart make SIP an appropriate analog for laboratory studies. The development of chemically pure analogs for ubiquitous soil minerals will allow for systematic research of the fundamental properties of these minerals.},
doi = {10.1016/j.chemgeo.2017.07.010},
journal = {Chemical Geology},
number = C,
volume = 470,
place = {United States},
year = {Sun Oct 01 00:00:00 EDT 2017},
month = {Sun Oct 01 00:00:00 EDT 2017}
}