A Southern Methodist University research team led by Professor and Mechanical Engineering Department Chair Ali Beskok and Professor Sevinc Sengor utilized InRedox AAO membranes to study the pressure driven flow dynamics of water through 5nm, 10nm, and 20nm diameter nanopores.  This study represents the first such measurements for pore diameters as small as 5 nm.

The water transport in in the pores was modeled using the Hagen-Poiseuille relation for laminar flows in cylindrical tubes with careful attention to the liquid-wall interface and the associated stick layer of water molecules over the hydroxylated alumina surface.

The measurements consistently showed a decrease of the effective diameter of the pores by 2.2 nm due the stick layer.  The simple yet elegant experimental design provide a direct and easy way to calculate the mass flow rate and measured pressure drop through nanoporous alumina substrates for a variety of transport-related applications.   Understanding the flow behavior in nanochannels is especially important in the development of electroosmotic pumps for lab-on-a-chip devices and for potential use of AAO as ion exchgangers in water treatment technologies.

Pressure‑driven water flow through hydrophilic alumina nanomembranes, Anil Koklu, Jianing Li, Sevinc Sengor, Ali Beskok, Microfluid Nanofluid (2017) 21(7), 124.