TY - JOUR
T1 - Molecular dynamics simulations of mineral surface wettability by water versus CO2
T2 - Thin films, contact angles, and capillary pressure in a silica nanopore
AU - Sun, Emily Wei Hsin
AU - Bourg, Ian C.
N1 - Funding Information:
This research was supported primarily by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Geosciences Program under Award DE-SC0018419. We acknowledge the support of the Natural Sciences and Engineering Research Council of Canada (NSERC), cette recherche a etefinanceé par le Conseil de Recherches en Sciences Naturelles et en Geniedu Canada (CRSNG), PGSD2-532635-2019. MD simulations were performed using resources of the National Energy Research Scientific Computing Center (NERSC), which is supported by the U.S. Department of Energy, Office of Science, under award DE-AC02-05CH11231. The research presented here was improved by discussions with Laura Lammers and Elliot Chang at UC Berkeley and with Howard Stone and Michael Celia at Princeton.
Funding Information:
This research was supported primarily by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Geosciences Program under Award DE-SC0018419. We acknowledge the support of the Natural Sciences and Engineering Research Council of Canada (NSERC), cette recherche a été financée par le Conseil de Recherches en Sciences Naturelles et en Génie du Canada (CRSNG), PGSD2-532635-2019. MD simulations were performed using resources of the National Energy Research Scientific Computing Center (NERSC), which is supported by the U.S. Department of Energy, Office of Science, under award DE-AC02-05CH11231. The research presented here was improved by discussions with Laura Lammers and Elliot Chang at UC Berkeley and with Howard Stone and Michael Celia at Princeton.
Publisher Copyright:
© 2020 American Chemical Society
PY - 2020/11/19
Y1 - 2020/11/19
N2 - The wettability of mineral surfaces is an important property influencing multiphase flow in soils and sedimentary rocks. In particular, for CO2 abatement technologies that rely on trapping supercritical CO2 in sedimentary formations, the wettability of relevant mineral surfaces by water is a poorly constrained fundamental property influencing stratigraphic and residual trapping. Theoretical studies have noted that adsorbed water films may hold a key to resolving many of the discrepancies in reported wettability data, but the transition from the droplet to the film is difficult to observe experimentally. The link between continuum and nanoscale observations can be elucidated using molecular dynamics (MD) and thermodynamic equations. We simulate water and CO2 at various pressures between quartz surfaces to probe the thickness of the adsorbed water film observed between the CO2 and quartz, and the radius of curvature of the fluid−fluid interface as a function of CO2 pressure. These results are discussed in the context of the relevant interfacial energies and Young's equation and the Gibbs CO2 surface excesses at various interfaces. We show that the augmented Young−Laplace equation accurately captures the relationship between the observed radius of curvature, the capillary pressure between the bulk fluid phases, and the disjoining pressure in the adsorbed water film. We examine the thermodynamics of thin water films in novel depth and present a new methodology for characterizing circularity approaching a mineral interface and for comparing continuum and nanoscale manifestations of wettability. We find that discrepancies in both the experimental and MD database may be influenced by proximity to solid surfaces and adsorbed wetting films.
AB - The wettability of mineral surfaces is an important property influencing multiphase flow in soils and sedimentary rocks. In particular, for CO2 abatement technologies that rely on trapping supercritical CO2 in sedimentary formations, the wettability of relevant mineral surfaces by water is a poorly constrained fundamental property influencing stratigraphic and residual trapping. Theoretical studies have noted that adsorbed water films may hold a key to resolving many of the discrepancies in reported wettability data, but the transition from the droplet to the film is difficult to observe experimentally. The link between continuum and nanoscale observations can be elucidated using molecular dynamics (MD) and thermodynamic equations. We simulate water and CO2 at various pressures between quartz surfaces to probe the thickness of the adsorbed water film observed between the CO2 and quartz, and the radius of curvature of the fluid−fluid interface as a function of CO2 pressure. These results are discussed in the context of the relevant interfacial energies and Young's equation and the Gibbs CO2 surface excesses at various interfaces. We show that the augmented Young−Laplace equation accurately captures the relationship between the observed radius of curvature, the capillary pressure between the bulk fluid phases, and the disjoining pressure in the adsorbed water film. We examine the thermodynamics of thin water films in novel depth and present a new methodology for characterizing circularity approaching a mineral interface and for comparing continuum and nanoscale manifestations of wettability. We find that discrepancies in both the experimental and MD database may be influenced by proximity to solid surfaces and adsorbed wetting films.
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U2 - 10.1021/acs.jpcc.0c07948
DO - 10.1021/acs.jpcc.0c07948
M3 - Article
AN - SCOPUS:85096881175
SN - 1932-7447
VL - 124
SP - 25382
EP - 25395
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 46
ER -