Influence of interaction strength on adsorption and transport properties of nanoconfined gas

Abstract

The surface properties of nanostructures play a key role in the storage and development of underground complex fluids. The adsorption and transport mechanism resulting from surface-molecule interaction force plays a key role in graphite nano-slits. These mechanisms explain their characteristically weaker gas adsorption but superior transport capabilities when compared to organic and inorganic nano-slit counterparts. Understanding the relationship between gas adsorption and transport in nano-slits with varying interaction forces is crucial for elucidating the fluid properties of different material surfaces. In this work, the effects of interaction on gas adsorption and transport property in nano-slits are quantitatively accessed by using molecular dynamics simulations. We found that as the interaction energy parameter between gas molecules and nano-slits, the adsorption density of gas molecules increases, and the self-diffusion coefficient of gas also decreases. The gas molecule preferentially adsorbed at the center of the graphene circle, which is the strongest interaction site of nano-slits. Considering the confined effect, the quantitative relation between self-diffusion coefficient, adsorption density and the ratio of pore size to interface interaction parameters (H/α) are respectively acquired to describe the self-diffusion and adsorption characteristics. A revised theoretical model that integrates adsorption and self-diffusion equations to predict the apparent permeability of gas molecules in nano-slits is proposed, demonstrating strong agreement with molecular simulation results. This work can be further revealed in gas purification and chemical industry through the fluid molecules transport behavior across various materials systems.