title: Factors governing the behaviour of aqueous methane in narrow pores.
abstract: All-atom equilibrium molecular dynamics simulations were employed to investigate the behaviour of aqueous methane confined in 1-nm-wide pores obtained from different materials. Models for silica, alumina and magnesium oxide were used to construct the slit-shaped pores. The results show that methane solubility in confined water strongly depends on the confining material, with silica yielding the highest solubility in the systems considered here. The molecular structure of confined water differs within the three pores, and density fluctuations reveal that the silica pore is effectively less 'hydrophilic' than the other two pores considered. Comparing the water fluctuation autocorrelation function with local diffusion coefficients of methane across the hydrated pores we observed a direct proportional coupling between methane and water dynamics. These simulation results help to understand the behaviour of gas in water confined within narrow subsurface formations, with possible implications for fluid transport.
authors.affiliation: Department of Chemical Engineering, University College London, Torrington Place, London WC1 E7JE, UK.
authors.forename: Anh
authors.initials: A
authors.lastname: Phan
authors.affiliation: School of Earth Sciences, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Cole
authors.affiliation: Department of Chemical Engineering, University College London, Torrington Place, London WC1 E7JE, UK a.striolo@ucl.ac.uk.
authors.forename: Alberto
authors.initials: A
authors.lastname: Striolo
keywords: aqueous systems; confined fluids; molecular simulation