Molecular dynamics simulations of interfacial structure, dynamics, and interfacial tension of tetrabutylammonium bromide aqueous solution in the presence of methane and carbon dioxide

Parisa Naeiji; Tom K Woo; Ryo Ohmura; Saman Alavi

doi:10.1063/5.0106707

Molecular dynamics simulations of interfacial structure, dynamics, and interfacial tension of tetrabutylammonium bromide aqueous solution in the presence of methane and carbon dioxide

J Chem Phys. 2022 Oct 21;157(15):154702. doi: 10.1063/5.0106707.

Authors

Parisa Naeiji¹, Tom K Woo¹, Ryo Ohmura², Saman Alavi¹

Affiliations

¹ Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa Ontario K1A 0R6, Canada.
² Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-Ku, Yokohama 223-8522, Japan.

PMID: 36272797
DOI: 10.1063/5.0106707

Abstract

The interfacial behavior of tetrabutylammonium bromide (TBAB) aqueous solutions in the absence of gas and the presence of methane and carbon dioxide gases is studied by molecular dynamics simulations. The aqueous TBAB phase, at concentrations similar to the solid semiclathrate hydrate (1:38 mol ratio), has a smaller interfacial tension and an increase in the gas molecules adsorbed at the interface compared to that in pure water. Both these factors may contribute to facilitating the uptake of the gases into the solid phase during the process of semiclathrate hydrate formation. At similar gas pressures, CO₂ is adsorbed preferentially compared to CH₄, giving it a higher surface density, due to the stronger intermolecular interactions of CO₂ molecules of the solution at the interface. The increase in relative adsorption of CH₄ at the solution surface compared to that in pure water surface is due to the hydrophobic interactions between the n-alkyl chains of the TBA⁺ cation and methane gas.