During the past decade, nanoparticles (1-100 nm) and nanocomposites have become the focus of many studies due to the unique properties of nanostructured materials that make them attractive for various applications. Due to their atomic and molecular interactions, nanoparticles and nanocomposites have unique and often favorable catalytic, mechanical, optical, electronic and / or other properties. For instance, nanocrystalline copper is up to 5 times harder than conventional micron sized copper particles. Nanocomposites, such as a homogenous mixture of different nanoparticles, can also exhibit improved properties. Other examples include coating and reacting nanoparticles with a second nanostructured phase. These processes are ideally suited to a fluidization process. However, in order to successfully use these applications, it is necessary to understand how nanoparticles can be fluidized.
This dissertation demonstrates that the fluidization of nanoparticles is indeed possible and in fact, significantly improvable with the addition of external forces or changes in certain conditions. Silica, alumina, and titania nanoparticles, whose sizes range from 7 to 21 nm in diameter, are fluidized in a conventional gravity-driven bed, a vibrated bed, a magnetically assisted bed, a rotating bed, and a bed under supercritical conditions. The key parameters affecting fluidization quality are examined in each fluidized bed system. An advanced laser and CCD camera system is used to view agglomerates as they are being fluidized. A novel method for estimating fluidized agglomerate size from liquid-fluidization theory and fractal analysis is shown to be in very good agreement with experimental data. Exciting applications in mixing and filtration are also presented.
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