(140b) Oscillation and Enhancement of Gas Solubility in Nanopores

Due to the strong interfacial interaction, gas solubility in confinement is rather different from that in bulk system. Although great attention has been paid to ‘oversolubility’ and ‘undersolubility’ as the pore size approaches to nanoscale, there still remains confusion over the two different phenomenon. Here, we investigate the influence of confinement in a slit-shaped pore on the solubility of critical gas in different liquid solvent by using classical density functional theory (DFT). We find that gas solubility in confinement is attributed to both the pore width and competing adsorption. When the pore width is nanoscale, gas solubility oscillates with a decaying envelope as the pore width increases. And competing adsorption becomes a dominating factor gradually with the increasing of pore width. If the solvent-wall interaction is larger than solute-wall interaction, gas solubility is suppressed; otherwise, gas solubility is enhanced. We redefined the gas solubility as the mole fraction of solute in pores, and this definition help us to clarify some confusion over ‘oversolubility’ and ‘undersolubility’. Finally, we investigate the effect of solute-wall interaction on gas solubility. Our results provide a theoretical guidance on the design of microreactor.