Interplay Between Adsorption and Hydrodynamics in Nanochannels: Towards Tunable Membranes

Area of Science:

• Physical Chemistry
• Chemical Engineering
• Materials Science

Background:

• Understanding fluid behavior in confined spaces is crucial for designing advanced materials and separation processes.
• Adsorption phenomena in nanopores are fundamental to catalysis, gas storage, and membrane technology.
• The interplay between flow and adsorption in near-critical mixtures remains an active area of research.

Purpose of the Study:

• To investigate the influence of flow on the adsorption of near-critical binary mixtures within nanopores.
• To identify and characterize distinct steady states of adsorption as a function of pore Péclet number.
• To explore the potential for tunable solute transport and separation based on flow conditions.

Main Methods:

• Simulations of binary mixture adsorption in nanopores under varying flow conditions.
• Analysis of adsorption isotherms and pore occupancy as a function of pore Péclet number (Pe_{p}).
• Identification of different steady-state regimes based on Pe_{p} and external pressure.

Main Results:

• Three distinct steady states of adsorption were identified, dependent on the pore Péclet number.
• At low Pe_{p}, the nanopore functions as a weakly selective membrane, separating the mixture.
• Intermediate Pe_{p} leads to shifted adsorption, enabling tunable and enhanced solute transport.
• High Pe_{p} reduces pore adsorption and causes long-ranged mixture dispersion.

Conclusions:

• Flow significantly modifies near-critical binary mixture adsorption in nanopores, leading to tunable transport properties.
• The identified steady states offer pathways for designing novel separation membranes and controlled solute delivery systems.
• This study provides fundamental insights into fluid dynamics and adsorption at the nanoscale.