The effect of thickness, pore size and structure of a nanomembrane on the flux and selectivity in reverse osmosis separations: a molecular dynamics study

Molecular dynamics simulations examine the effect of pore size, structure and membrane thickness on flux and selectivity in reverse osmosis. Membranes are modeled using layers of barrier molecules tethered harmonically to periodic lattice sites. Permeation occurs within a Knudsen like regime where close confinement in nanopores precludes water–water interactions, leaving water–pore interactions to determine hydraulic resistance. Results show the solvent flux to be rather insensitive to an appropriately defined tortuosity. Ion selectivity seems to correlate primarily with overall hydraulic resistance, irrespective of the number of membrane layers.