An investigation of some H2S thermodynamical properties at the water interface under pressurised conditions through molecular dynamics. (19th March 2022)

• Record Type: Journal Article
• Authors: Ofori, Kofi; Phan, Chi M.; Barifcani, Ahmed; Iglauer, Stefan
• Is Part Of: Molecular physics. Volume 120:Number 6(2022)
• Publication Date: 2022-03-19
• Subjects: Molecular dynamics -- interfacial tension -- absorption -- adsorption -- interfacial thickness; Molecules -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Molécules -- Périodiques; Chimie physique et théorique -- Périodiques; 539.6.05
• DOI: 10.1080/00268976.2021.2011972
• Languages: English
• ISSNs: 0026-8976

Abstract

Abstract : Geo-sequestration of hydrogen sulphide in geological formations is a disposal method with potential economic benefits. The process is governed by among other things, variables such as the water-H2 S interfacial tension, H2 S absorption into water and H2 S adsorption onto water. However, the influence of pressure on these parameters is poorly understood. This study investigates these parameters as functions of pressure and temperature via molecular dynamics (MD) simulations. Simulations were carried out for the isotherms 40, 70 and 120°C and a pressure range of 0.45–15 MPa. A comparison was made against N2 -water systems to clarify the effects of adsorption on interfacial tension, γ . The predicted water-H2 S interfacial tension and phase densities below H2 S saturation pressure matched experimental values well. The adsorption can be quantified via the interfacial thickness, δ, which correlated well with the H2 S pressures. Above the H2 S saturation pressure, the interfacial thickness remained constant, which indicated a saturation of H2 S at the water surface. Further increment of pressure above saturation revealed a significant absorption of H2 S. The molecular analysis indicated the main binding interaction is between O of water and H of H2 S, instead of S and H of water due to the electronegativity of the water O atom. GRAPHICAL ABSTRACT: UF0001