Structure and Dynamics of Interfacial Water on Muscovite Surface under Different Temperature Conditions (298 K to 673 K): Molecular Dynamics Investigation

Abstract

We performed molecular dynamics (MD) simulations to study structure, stability, and dynamics of the water adsorption layer on muscovite mica at several temperatures (from 298 K to 673 K) and pressures (0.1 MPa, 10 MPa, and 50 MPa). We studied the structure of the adsorption layers with three characteristic peaks of density and orientation of H2O molecules in one-dimensional and two-dimensional profiles. The results show that the water adsorption layers become less structured and more mobile as the temperature increases. We also found the first and the second layers are less diffusive than the third one, and the difference of diffusivity gets unclear as the temperature increases. Finally, we discuss implications to hydration forces and wettability, which are significant interfacial properties of the multiphase fluids system such as water/gas/mineral systems, from the viewpoint of water adsorption film with nanometer thickness.

Effect of Surface Coverage of Water Molecules on Methane Adsorption on Muscovite and Pyrophyllite: Molecular Dynamics Study

“…At θ > 1.0, where the height of the two sharp peaks of H 2 O ( d ∼ 0.2 and 0.35 nm) in Figure a remain almost the same, the pattern of the density maps does not change significantly. These panels for the H 2 O molecules at θ > 1.0 are in good agreement with the water/muscovite two-phase system calculated in a previous work …”

“…The third peak (0.5 nm < d < 0.7 nm) becomes prominent at θ > 1.0, where the growth of the two peaks almost ceases. In the first and second peak regions, H 2 O molecules adsorb on the muscovite surface with a polarity-based orientation angle, unlike those in the bulk phase. ,,, This implies that the H 2 O molecules are arranged in the same orientation on the muscovite surface, resulting in the formation of a structured layer on the surface, where H 2 O molecules are less mobile than in the bulk phase. ,,, On pyrophyllite, the water density increases in the whole range of d < 1.0 nm, unlike on muscovite. This shows that the water distribution on pyrophyllite is different from that on muscovite, especially in the range d < 1.0 nm, as has been suggested by the snapshots in Figure .…”

“…At θ = 0.0, the density is high at the center of the ditrigonal cavity. Some ditrigonal sites show a low density because K + adsorbs at the center of the ditrigonal cavity [for example, refs and ]. At θ = 0.10, the density of CH 4 around Al (shown as a white circle) decreases, and this trend is more visible at θ = 0.45.…”

“…In the first and second peak regions, H 2 O molecules adsorb on the muscovite surface with a polarity-based orientation angle, unlike those in the bulk phase. 75,78,84,85 This implies that the H 2 O molecules are arranged in the same orientation on the muscovite surface, resulting in the formation of a structured layer on the surface, where H 2 O molecules are less mobile than in the bulk phase. 75,78,86,87 On pyrophyllite, the water density increases in the whole range of d < 1.0 nm, unlike on muscovite.…”

“…Cations are adsorbed on the charged surface, and a K + -muscovite model was adopted in this study. The same arrangement as in previous studies − was used for isomorphic substitution. A snapshot of the tetrahedral layer composed of Si and Al is shown in the left panel of Figure .…”