390037 Separation of Polydispersed Nanoparticles in Suspension
Separation of mondispersed nanoparticles in suspension is an extremely difficult task let alone separation of polydispersed nanoparticles in suspension. The process rate is usually very small using membranes, set aside plugging and fouling of the membrane over time caused by these nanoparticles. This is especially notorious with particles of different sizes as found in polydispersed suspension.
Centrifuges, for example high-speed decanters  and disk stack , can be used effectively to classify slurry with polydispersed particles of one micron and above in high volume flow rate using decanters. On the other hand, this paper shows how this can be done for particles in the sub-micron and nano-ranges, which is absolutely unconventional.
Particles with the same density can be sorted out according to their size range by making various “cuts”, which is determined primarily by the centrifugal acceleration and flow rate. Particles of different densities and different sizes can be done similarly. This paper illustrates how this can be carried out for small kaolin particles 200 minus to 800 nm in suspension using an interesting approach based on centrifugation.
After sorting, particles of a given size range can be further agglomerated by coagulation followed by centrifugal separation for high solids recovery of the nanoparticles.
 Wallace Woon-Fong Leung, Industrial Centrifugation Technology, McGraw-Hill, New York, NY, 1998.
 Wallace Woon-Fong Leung, Centrifugal Separation in Biotechnology, Academic Press, Oxford, UK, 2007.