TY - JOUR
T1 - Role of Electrochemical Surface Potential and Irradiation on Garnet-Type Almandine's Dissolution Kinetics
AU - Hsiao, Yi Hsuan
AU - La Plante, Erika Callagon
AU - Krishnan, N. M.Anoop
AU - Dobbs, Howard A.
AU - Le Pape, Yann
AU - Neithalath, Narayanan
AU - Bauchy, Mathieu
AU - Israelachvili, Jacob N.
AU - Sant, Gaurav N.
N1 - Funding Information:
The authors acknowledge financial support for this research provided by the Department of Energy’s Nuclear Energy University Program (DOE-NEUP: DE-NE0008398), National Science Foundation (CAREER award: 1253269), the U.S. Department of Transportation (U.S. DOT) through the Federal Highway Administration (DTFH61-13-H-00011), and University of California, Los Angeles (UCLA). The contents of this paper reflect the views and opinions of the authors who are responsible for the accuracy of the data presented. This research was carried out in the Laboratory for the Chemistry of Construction Materials (LC2), Molecular Instrumentation Center, and Laboratory for the Physics of Amorphous and Inorganic Solids (PARISlab) at UCLA. As such, the authors gratefully acknowledge the support that has made these laboratories and their operations possible.
Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/8/2
Y1 - 2018/8/2
N2 - Nanoscale-resolved quantifications of almandine's (Fe3Al2(SiO4)3) dissolution rates across a range of pHs (1 ≤ pH ≤ 13) - established using vertical scanning interferometry - reveal that its dissolution rate achieves a minimum around pH 5. This minimum coincides with almandine's point of zero charge. These trends in almandine's dissolution can be estimated using the Butler-Volmer equation that reveals linkages between surface potentials and dissolution rates, demonstrating proton- and hydroxyl-promoted breakage of Si-O bonds. In contrast to well-polymerized silicates, the dissolution of almandine can also occur through the rupture of its cationic bonds. This behavior is reflected in the observed influences of irradiation on its dissolution kinetics. Molecular dynamics simulations highlight that irradiation induces alterations in the atomic structure of almandine by reducing the coordination state of the cations (Fe2+ and Al3+), thereby enhancing its reactivity by a factor of two. This is consistent with the minor change induced in the structure of almandine's silicate backbone, whose surface charge densities produce the observed pH dependence (and rate control) of dissolution rates. These findings reveal the influential roles of surface potential arising from solution pH and atomic scale alterations on affecting the reactivity of garnet-type silicates.
AB - Nanoscale-resolved quantifications of almandine's (Fe3Al2(SiO4)3) dissolution rates across a range of pHs (1 ≤ pH ≤ 13) - established using vertical scanning interferometry - reveal that its dissolution rate achieves a minimum around pH 5. This minimum coincides with almandine's point of zero charge. These trends in almandine's dissolution can be estimated using the Butler-Volmer equation that reveals linkages between surface potentials and dissolution rates, demonstrating proton- and hydroxyl-promoted breakage of Si-O bonds. In contrast to well-polymerized silicates, the dissolution of almandine can also occur through the rupture of its cationic bonds. This behavior is reflected in the observed influences of irradiation on its dissolution kinetics. Molecular dynamics simulations highlight that irradiation induces alterations in the atomic structure of almandine by reducing the coordination state of the cations (Fe2+ and Al3+), thereby enhancing its reactivity by a factor of two. This is consistent with the minor change induced in the structure of almandine's silicate backbone, whose surface charge densities produce the observed pH dependence (and rate control) of dissolution rates. These findings reveal the influential roles of surface potential arising from solution pH and atomic scale alterations on affecting the reactivity of garnet-type silicates.
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U2 - 10.1021/acs.jpcc.8b04459
DO - 10.1021/acs.jpcc.8b04459
M3 - Article
AN - SCOPUS:85049664328
VL - 122
SP - 17268
EP - 17277
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
SN - 1932-7447
IS - 30
ER -