Interfacial properties of 1-ethyl-3-methylimidazolium glycinate ionic liquid regarding CO2, SO2 and water from molecular dynamics

Abstract

The surface properties of 1-ethyl-3-methylimidazolium glycinate ionic liquid, as a model of amino acid-based compounds, in contact with a vacuum, CO2, SO2 and flue gas phases are studied using molecular dynamics simulations. The orientation of ions at the interface and the characteristics of the adsorbed gas layers are inferred from the theoretical study. Densely adsorbed layers are obtained for CO2 molecules at fast adsorption rates, with CO2 interacting preferentially with imidazolium cations at the interface. SO2 is adsorbed faster than CO2 at the ionic liquid interface, showing large affinity for glycinate anions. The contact of the studied ionic liquid with a model flue gas leads to the fast development of an adsorbed layer of water molecules, with CO2 molecules being adsorbed on top of this water layer. Therefore, the interface is initially blocked by the presence of water molecules, which would delay the adsorption and diffusion of CO2 molecules across the ionic liquid interface. 2016 Elsevier B.V. All rights reserved.