Fluidization of nanoparticles: A modified Richardson-Zaki Law

Fluidization of nanoparticles is receiving increasing interest, as its role is getting bigger in nanopowder-based commercial applications namely, semiconductors, coatings, cosmetics, electronics, sensors and drug delivery. These particles, which are only about d super(p)~1-100 nm in size, provide high contact and reaction efficiencies, thus delivering special unique advantages over traditional materials. Even though according to small size of these particles one would predict Geldart C behavior, there is growing experimental evidence that nanoparticles can be uniformly fluidized for an extended window of gas velocities, that is primary particle size and density cannot be taken as representative parameters for predicting their fluidization behavior. It is found that the extension of the non-bubbling fluidization shorten as particle size is increased and shrink to zero in the limit of nonagglomerated particles super(2).