Dynamics Slowdown Induced by Gas Oversolubility in Nanoconfined Fluids

Area of Science:

• Nanoscale science
• Physical chemistry
• Geophysics

Background:

• Oversolubility, higher gas solubility in nanoconfined liquids than bulk, is known but its dynamic impact is unexplored.
• This phenomenon is crucial for separations, catalysis, and geological applications like pollutant migration and carbon capture.

Purpose of the Study:

• To investigate the impact of gas oversolubility on fluid dynamics in hydrated nanoporous materials.
• To explore the relationship between oversolubility, viscosity, and diffusion of water and ions.

Main Methods:

• Atom-scale simulations
• Nuclear Magnetic Resonance (NMR) experiments

Main Results:

• Gas oversolubility was confirmed in hydrated nanoporous materials, reducing water and ion diffusivities by 10-60%.
• Diffusivity reduction is linked to increased confined fluid viscosity due to decreased free volume, rationalized by the Stokes-Einstein relation.
• The dynamical slowdown affects water and ions identically, intensifying with stronger gas-liquid/solid interactions.

Conclusions:

• Oversolubility significantly impacts fluid dynamics in nanoporous systems.
• A formalism is provided to understand fluid diffusion under gas solubility effects in nanoconfined environments.
• Findings are relevant for geological applications and separation technologies.