Interplay between adsorption and hydrodynamics in nanochannels: towards tunable membranes

TL;DR

This study explores how flow influences adsorption in nanopores, revealing three steady states that enable tunable membrane selectivity and solute transport by adjusting flow conditions.

Contribution

It demonstrates the dynamic interplay between flow and adsorption in nanochannels, introducing a method to control membrane properties via flow rate adjustments.

Findings

Small Pe_p: pore acts as a weakly selective membrane.

Intermediate Pe_p: flow shifts adsorption, enhancing transport.

Large Pe_p: adsorption reduces, causing dispersion far from pore.

Abstract

We study how adsorption of a near-critical binary mixture in a nanopore is modified by flow inside the pore. We identify three types of steady states upon variation of the pore P\'{e}clet number (${\rm Pe}_p$), which can be reversibly accessed by the application of an external pressure. Interestingly, for small ${\rm Pe}_p$ the pore acts as a weakly selective membrane which separates the mixture. For intermediate ${\rm Pe}_p$, the flow effectively shifts the adsorption in the pore thereby opening possibilities for enhanced and tunable solute transport through the pore. For large ${\rm Pe}_p$, the adsorption is progressively reduced inside the pore, accompanied by a long ranged dispersion of the mixture far from the pore.