Japan Geoscience Union Meeting 2016

Presentation information


Symbol S (Solid Earth Sciences) » S-MP Mineralogy & Petrology

[S-MP44] Dynamics of melt, ductile and brittle rock mass and energy system

Wed. May 25, 2016 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall HALL6)

Convener:*Noriyoshi Tsuchiya(Graduate School of Environmental Studies, Tohoku University), Hiroshi Asanuma(AIST), Yasuo Ogawa(Volcanic Fluid Research Center Tokyo Institute of Technology), Shigemi Naganawa(The University of Tokyo)

5:15 PM - 6:30 PM

[SMP44-P06] Physicochemical properties of water confined between quartz surfaces at elevated temperatures by molecular dynamics simulation

*Satoru Ishikawa1, Hiroshi Sakuma2, Noriyoshi Tsuchiya1 (1.Graduate School of Environmental Studies, Tohoku University, 2.National Institute for Materials Science)

Keywords:interfacial water, quartz, Molecular dynamics, self-diffusion coefficient

Interfacial water, of which physicochemical properties were different from bulk water, was recognized in the vicinity of solid surface. The physical properties of interfacial water show unique characteristics, for example the self-diffusion coefficient, thermal expansion coefficient and freezing point. The property of interfacial water is essential for understanding geophysical and geochemical phenomena.
Although the phenomena of interfacial water have been studied theoretically and experimentally, the dynamics of the interface at high temperature and pressure remains unclear. In this study, we performed the molecular dynamics (MD) simulations to understand the structure and dynamics of water confined between quartz surfaces at 298-573 K, 10 MPa.
We tested some systems of water confined between quartz surfaces characterized by the termination of silanol (Si-OH) group. At low temperature, the density profiles showed several layered structures near the surface, and the self-diffusion coefficient was reduced in 1.0 nm distance from the surface. At high temperatures, the layered structures were disappeared and the self-diffusion coefficient was reduced in 1.5 nm.
The activation energies of the diffusion process in confined geometries were calculated based on the Arrhenius theory, and these values were close to that of bulk water. This implied that the diffusion mechanism in confined geometries is similar that in bulk and the activation energy may be interpreted by the dissociation energy of hydrogen bond.
Based on these results, the relationship of between geophysical phenomena and interfacial water will be discussed.