Structure and dynamics of water on Li+-, Na+-, K+-, Cs+-, H3O+-exchanged muscovite surfaces

A molecular dynamics study

Hiroshi Sakuma, Katsuyuki Kawamura

Research output: Contribution to journalArticle

75 Citations (Scopus)

Abstract

The distribution and dynamics of water molecules and monovalent cations (Li+, Na+, K+, Cs+, and H3O+) on muscovite surfaces were investigated by molecular dynamics (MD) simulations. The direct comparison of calculated X-ray reflectivity profiles and electron density profiles with experiments revealed the precise structure at the aqueous monovalent electrolyte solutions/muscovite interface. To explain the experimentally observed electron density profiles for the CsCl solution-muscovite interface, the co-adsorption of Cs+ and Cl- ion pairs would be necessary. Two types of inner-sphere complexes and one type of outer-sphere complex were observed for hydrated Li+ ions near the muscovite surface. For Na+, K+, Cs+, and H3O+ ions, the inner-sphere complexes were stable on the muscovite surface. The density oscillation of water molecules was observed to approximately 1.5nm from the muscovite surface. The number of peaks and the locations for the density of water oxygen atoms were almost similar among the water molecules coordinated to Li+, Na+, K+, and H3O+ ions adsorbed on the muscovite surfaces. The water molecules around Cs+ ions that were adsorbed to muscovite surfaces seemed to avoid coordinating with Cs+ ions on the surface, and the density of water oxygen near the muscovite surface decreased relative to that in a bulk state. There was no significant difference in self-diffusion, viscosity, retention time, and reorientation time of water molecules among different cations adsorbed to muscovite surfaces. These translational and rotational motions of water molecules located at less than 1nm from the muscovite surfaces were slower than those in a bulk state. A significant difference was observed for the exchange times of water molecules around monovalent cations. The exchange time of water molecules was long around Li+ ions and decreased with an increase in the ionic radius.

Original languageEnglish
Pages (from-to)63-81
Number of pages19
JournalGeochimica et Cosmochimica Acta
Volume75
Issue number1
DOIs
Publication statusPublished - Jan 1 2011
Externally publishedYes

Fingerprint

muscovite
Molecular dynamics
Water
Ions
Molecules
ion
water
Monovalent Cations
cation
electron density
Carrier concentration
Oxygen
oxygen
reflectivity
electrolyte
Electrolytes
Cations
viscosity
oscillation
Viscosity

ASJC Scopus subject areas

  • Geochemistry and Petrology

Cite this

Structure and dynamics of water on Li+-, Na+-, K+-, Cs+-, H3O+-exchanged muscovite surfaces : A molecular dynamics study. / Sakuma, Hiroshi; Kawamura, Katsuyuki.

In: Geochimica et Cosmochimica Acta, Vol. 75, No. 1, 01.01.2011, p. 63-81.

Research output: Contribution to journalArticle

@article{c361acb8843d41bf8e5fd03559a0e8e5,
title = "Structure and dynamics of water on Li+-, Na+-, K+-, Cs+-, H3O+-exchanged muscovite surfaces: A molecular dynamics study",
abstract = "The distribution and dynamics of water molecules and monovalent cations (Li+, Na+, K+, Cs+, and H3O+) on muscovite surfaces were investigated by molecular dynamics (MD) simulations. The direct comparison of calculated X-ray reflectivity profiles and electron density profiles with experiments revealed the precise structure at the aqueous monovalent electrolyte solutions/muscovite interface. To explain the experimentally observed electron density profiles for the CsCl solution-muscovite interface, the co-adsorption of Cs+ and Cl- ion pairs would be necessary. Two types of inner-sphere complexes and one type of outer-sphere complex were observed for hydrated Li+ ions near the muscovite surface. For Na+, K+, Cs+, and H3O+ ions, the inner-sphere complexes were stable on the muscovite surface. The density oscillation of water molecules was observed to approximately 1.5nm from the muscovite surface. The number of peaks and the locations for the density of water oxygen atoms were almost similar among the water molecules coordinated to Li+, Na+, K+, and H3O+ ions adsorbed on the muscovite surfaces. The water molecules around Cs+ ions that were adsorbed to muscovite surfaces seemed to avoid coordinating with Cs+ ions on the surface, and the density of water oxygen near the muscovite surface decreased relative to that in a bulk state. There was no significant difference in self-diffusion, viscosity, retention time, and reorientation time of water molecules among different cations adsorbed to muscovite surfaces. These translational and rotational motions of water molecules located at less than 1nm from the muscovite surfaces were slower than those in a bulk state. A significant difference was observed for the exchange times of water molecules around monovalent cations. The exchange time of water molecules was long around Li+ ions and decreased with an increase in the ionic radius.",
author = "Hiroshi Sakuma and Katsuyuki Kawamura",
year = "2011",
month = "1",
day = "1",
doi = "10.1016/j.gca.2010.10.007",
language = "English",
volume = "75",
pages = "63--81",
journal = "Geochmica et Cosmochimica Acta",
issn = "0016-7037",
publisher = "Elsevier Limited",
number = "1",

}

TY - JOUR

T1 - Structure and dynamics of water on Li+-, Na+-, K+-, Cs+-, H3O+-exchanged muscovite surfaces

T2 - A molecular dynamics study

AU - Sakuma, Hiroshi

AU - Kawamura, Katsuyuki

PY - 2011/1/1

Y1 - 2011/1/1

N2 - The distribution and dynamics of water molecules and monovalent cations (Li+, Na+, K+, Cs+, and H3O+) on muscovite surfaces were investigated by molecular dynamics (MD) simulations. The direct comparison of calculated X-ray reflectivity profiles and electron density profiles with experiments revealed the precise structure at the aqueous monovalent electrolyte solutions/muscovite interface. To explain the experimentally observed electron density profiles for the CsCl solution-muscovite interface, the co-adsorption of Cs+ and Cl- ion pairs would be necessary. Two types of inner-sphere complexes and one type of outer-sphere complex were observed for hydrated Li+ ions near the muscovite surface. For Na+, K+, Cs+, and H3O+ ions, the inner-sphere complexes were stable on the muscovite surface. The density oscillation of water molecules was observed to approximately 1.5nm from the muscovite surface. The number of peaks and the locations for the density of water oxygen atoms were almost similar among the water molecules coordinated to Li+, Na+, K+, and H3O+ ions adsorbed on the muscovite surfaces. The water molecules around Cs+ ions that were adsorbed to muscovite surfaces seemed to avoid coordinating with Cs+ ions on the surface, and the density of water oxygen near the muscovite surface decreased relative to that in a bulk state. There was no significant difference in self-diffusion, viscosity, retention time, and reorientation time of water molecules among different cations adsorbed to muscovite surfaces. These translational and rotational motions of water molecules located at less than 1nm from the muscovite surfaces were slower than those in a bulk state. A significant difference was observed for the exchange times of water molecules around monovalent cations. The exchange time of water molecules was long around Li+ ions and decreased with an increase in the ionic radius.

AB - The distribution and dynamics of water molecules and monovalent cations (Li+, Na+, K+, Cs+, and H3O+) on muscovite surfaces were investigated by molecular dynamics (MD) simulations. The direct comparison of calculated X-ray reflectivity profiles and electron density profiles with experiments revealed the precise structure at the aqueous monovalent electrolyte solutions/muscovite interface. To explain the experimentally observed electron density profiles for the CsCl solution-muscovite interface, the co-adsorption of Cs+ and Cl- ion pairs would be necessary. Two types of inner-sphere complexes and one type of outer-sphere complex were observed for hydrated Li+ ions near the muscovite surface. For Na+, K+, Cs+, and H3O+ ions, the inner-sphere complexes were stable on the muscovite surface. The density oscillation of water molecules was observed to approximately 1.5nm from the muscovite surface. The number of peaks and the locations for the density of water oxygen atoms were almost similar among the water molecules coordinated to Li+, Na+, K+, and H3O+ ions adsorbed on the muscovite surfaces. The water molecules around Cs+ ions that were adsorbed to muscovite surfaces seemed to avoid coordinating with Cs+ ions on the surface, and the density of water oxygen near the muscovite surface decreased relative to that in a bulk state. There was no significant difference in self-diffusion, viscosity, retention time, and reorientation time of water molecules among different cations adsorbed to muscovite surfaces. These translational and rotational motions of water molecules located at less than 1nm from the muscovite surfaces were slower than those in a bulk state. A significant difference was observed for the exchange times of water molecules around monovalent cations. The exchange time of water molecules was long around Li+ ions and decreased with an increase in the ionic radius.

UR - http://www.scopus.com/inward/record.url?scp=78649635844&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=78649635844&partnerID=8YFLogxK

U2 - 10.1016/j.gca.2010.10.007

DO - 10.1016/j.gca.2010.10.007

M3 - Article

VL - 75

SP - 63

EP - 81

JO - Geochmica et Cosmochimica Acta

JF - Geochmica et Cosmochimica Acta

SN - 0016-7037

IS - 1

ER -