Interplay between Adsorption and Hydrodynamics in Nanochannels: Towards Tunable Membranes

We study how the 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 Péclet number (Pep), which can be reversibly accessed by the application of an external pressure. Interestingly, for small Pep the pore acts as a weakly selective membrane which separates the mixture. For intermediate Pep, the flow effectively shifts the adsorption in the pore, thereby opening possibilities for enhanced and tunable solute transport through the pore. For large Pep, the adsorption is progressively reduced inside the pore, accompanied by a long-ranged dispersion of the mixture far from the pore.