Behavior of micro and nanoaluminas used in the preparation of colloidal systems and filters for water contaminants

Reference Presenter Authors
06-108 Nelcy Della Santina Mohallem Mohallem, N.D.(Universidade Federal de Minas Gerais); de Paulo, P.H.(Universidade Federal de MInas Gerais); de Castro, M.F.(UFMG); The nanomaterials behavior has considerable complexity, leading to different mechanism of formation when used to prepare colloidal systems and sintered materials as filters and ceramics. In addition, this mechanism depends directly on the surface free energy related to the dimensions of the particles. In this work, we study the formation of colloidal systems and densification process of pellets prepared with different amounts of micro and nanoparticulate alumina. The pellets were pressed and densified in different temperatures between 1200 and 1400 °C in different times. The alumina particles of nano and micro dimension and the pellets were structural, textural and morphologically characterized. X-ray diffraction, scanning and transmission electron microscopy, electron microprobe and gas adsorption-desorption techniques were used to determine the structural phases, specific surface area, porosity, size and shape of the studied materials. Tests of sedimentation were realized with the powders that showed different behaviors, depending of the amount of nanoparticles in solution. The densification tests of the pellets showed that the pellets from nanostructured alumina is denser than the pellets from microstructured alumina and the use of a mixture of these materials in different amounts facilitates the confection of filters with a modulation of the pore dimensions, adequate to separation of contaminants in water.
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