A separation membrane is a key component in both nanofiltration and reverse osmosis filtration systems. Reducing the thickness of the membrane reduces the pressure that needs to be applied across the membrane in order to achieve a certain amount of flux, a major operational cost in these devices. A recent collaboration between users of Argonne’s Center for Nanoscale Materials (CNM) from the University of Chicago, University of Illinois at Chicago and CNM’s Electronic & Magnetic Materials & Devices Group has produced the thinnest nanofiltration membrane achieved thus far (~30nm), made of just four layers of nanoparticles. Guided by atomistic molecular dynamics simulations, it was found that molecular transport occurs through pore-like regions between close-packed nanoparticles and that dielectric exclusion dominates the charge-dependent rejection. This research opens up many new possibilities for using nanoparticles in nanofiltration and molecular separation. More »