Entrance effects in concentration-gradient-driven flow through an ultrathin porous membrane

Area of Science:

• Materials Science
• Chemical Engineering
• Physical Chemistry

Background:

• Transport of liquid mixtures via porous membranes is crucial for desalination, chemical separations, and energy harvesting.
• Ultrathin membranes from 2D nanomaterials offer promising performance for these applications.

Purpose of the Study:

• To derive general equations for solution and solute fluxes through ultrathin membranes driven by solute concentration gradients.
• To establish scaling laws for these fluxes based on pore size and solute-membrane interactions.

Main Methods:

• Derivation of general flux equations for circular pores in ultrathin planar membranes.
• Validation using finite-element numerical simulations for weak solute-membrane interactions.
• Development of scaling laws for flux dependence on pore size and interaction parameters.

Main Results:

• Novel equations accurately predict fluid fluxes in simulations with weak solute-membrane interactions.
• Derived scaling laws reveal distinct transport behaviors compared to long cylindrical pores or other driving forces.
• Demonstrated differences in scaling relationships for concentration-gradient-driven flow.

Conclusions:

• The derived equations and scaling laws provide a fundamental understanding of transport through ultrathin membranes.
• Findings have broad implications for designing and optimizing membrane-based separation and energy harvesting technologies.
• Highlights the unique transport phenomena in membranes with thickness comparable to pore size.