Water transport mechanisms during pressure-driven transport through polyamide nanogaps.

Abstract

Molecular-scale simulations of pressure-driven transport through polyamide nanogaps (5-100 Å) were performed to investigate fundamental transport mechanisms. Results show that transport in nanogaps $\le$  10 Å is always subdiffusive, but superdiffusive transport was observed in nanogaps $\ge$  20 Å. Near typical operating pressures for applications ( $\Delta p$  = 100 atm), only the 100 Å nanogap exhibited superdiffusive behavior. Since openings in common membrane materials are typically <20 Å, results indicate that subdiffusive to diffusive transport dominates for typical applications, such as reverse osmosis.