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Title: Surface Charge Effects on Fe(II) Sorption and Oxidation at (110) Goethite Surfaces

Abstract

Iron(III) oxides and oxyhydroxides are among the most reactive minerals in the environment, with surfaces that become charged when immersed in water. The governing role of surface charge over interfacial processes such as metal sorption is well understood. However, its role in interfacial redox reactions, such as when metal sorption is coupled to interfacial electron transfer (ET), is not. This is mainly because surface charge affects not only the types and densities of surface complexes formed but also their respective driving forces for ET. An important case is Fe(II)-catalyzed recrystallization of Fe(III)-oxyhydroxides, in which Fe(II) sorption and interfacial ET are closely linked. We used replica-exchange constant-pH molecular dynamics simulations (Zarzycki, P.; Smith, D. M.; Rosso, K. M. J. Chem. Theory Comput. 2015, 11, 1715–1724) to calculate the distance-dependent electrostatic potential at charged (110) surfaces of goethite particles, assessing its effect on previously computed Fe(II) sorption and interfacial ET free energies (Zarzycki, P.; Kerisit, S.; Rosso, K. M. J. Phys. Chem. C 2015, 119, 3111–3123). We show that Fe(II) adsorbs preferentially as an inner-sphere complex on the negatively charged surface, and as an outer-sphere complex on the positively charged surface because of both electrostatic repulsion and high energy barriers that arisemore » from ordered water layers at the interface. The separation distance between adsorbed Fe(II) and the surface largely dictates adiabatic versus nonadiabatic ET regimes for this interface. The findings help unravel the pH dependence of Fe(II)-catalyzed recrystallization of goethite.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Energy Geosciences Division
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1509676
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 122; Journal Issue: 18; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Zarzycki, Piotr, and Rosso, Kevin M. Surface Charge Effects on Fe(II) Sorption and Oxidation at (110) Goethite Surfaces. United States: N. p., 2018. Web. doi:10.1021/acs.jpcc.8b02099.
Zarzycki, Piotr, & Rosso, Kevin M. Surface Charge Effects on Fe(II) Sorption and Oxidation at (110) Goethite Surfaces. United States. doi:10.1021/acs.jpcc.8b02099.
Zarzycki, Piotr, and Rosso, Kevin M. Wed . "Surface Charge Effects on Fe(II) Sorption and Oxidation at (110) Goethite Surfaces". United States. doi:10.1021/acs.jpcc.8b02099. https://www.osti.gov/servlets/purl/1509676.
@article{osti_1509676,
title = {Surface Charge Effects on Fe(II) Sorption and Oxidation at (110) Goethite Surfaces},
author = {Zarzycki, Piotr and Rosso, Kevin M.},
abstractNote = {Iron(III) oxides and oxyhydroxides are among the most reactive minerals in the environment, with surfaces that become charged when immersed in water. The governing role of surface charge over interfacial processes such as metal sorption is well understood. However, its role in interfacial redox reactions, such as when metal sorption is coupled to interfacial electron transfer (ET), is not. This is mainly because surface charge affects not only the types and densities of surface complexes formed but also their respective driving forces for ET. An important case is Fe(II)-catalyzed recrystallization of Fe(III)-oxyhydroxides, in which Fe(II) sorption and interfacial ET are closely linked. We used replica-exchange constant-pH molecular dynamics simulations (Zarzycki, P.; Smith, D. M.; Rosso, K. M. J. Chem. Theory Comput. 2015, 11, 1715–1724) to calculate the distance-dependent electrostatic potential at charged (110) surfaces of goethite particles, assessing its effect on previously computed Fe(II) sorption and interfacial ET free energies (Zarzycki, P.; Kerisit, S.; Rosso, K. M. J. Phys. Chem. C 2015, 119, 3111–3123). We show that Fe(II) adsorbs preferentially as an inner-sphere complex on the negatively charged surface, and as an outer-sphere complex on the positively charged surface because of both electrostatic repulsion and high energy barriers that arise from ordered water layers at the interface. The separation distance between adsorbed Fe(II) and the surface largely dictates adiabatic versus nonadiabatic ET regimes for this interface. The findings help unravel the pH dependence of Fe(II)-catalyzed recrystallization of goethite.},
doi = {10.1021/acs.jpcc.8b02099},
journal = {Journal of Physical Chemistry. C},
issn = {1932-7447},
number = 18,
volume = 122,
place = {United States},
year = {2018},
month = {4}
}

Journal Article:
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