Grand Séminaire d'Institut

Vendredi 21 Juin 2019 à 11h00.

Entrance effects in fluid flow through ultrathin porous membranes

''Fluid transport through pores and porous membranes plays a key role in many processes of fundamental and practical interest, including cellular homeostasis in biological systems, chemical separations, desalination, and energy harvesting. Most theoretical models and simulations of fluid transport in porous media have considered flow only within pores assumed to be of infinite length and have neglected the effect of transport between the membrane pores and the fluid outside the membrane. But these so-called entrance or access effects can dominate fluid transport processes when the membrane thickness approaches the characteristic pore size. The most extreme example of this situation are membranes of atomic thickness made from novel 2D nanomaterials, such as graphene or molybenum disulfide, which have attracted great interest recently, as they have shown exceptional properties compared with conventional membranes in a number of applications. In this talk, I will present general theoretical models for fluid flow through ultrathin membranes driven by solute concentration gradients or electric fields, which I will show to be quantitatively accurate by comparison with continuum hydrodynamic calculations and molecular dynamics simulations. I will discuss how the solute and solvent fluxes through an ultrathin membrane are controlled by important microscopic parameters such as pore size and the strength and range of fluid-membrane interactions, and how they show markedly different behavior compared with the corresponding fluxes through a thick membrane. This behavior has broad implications for transport of liquids through membranes of molecular thickness.''