In recent years, scientific research showed an increasing interest in the field of nanotechnology, resulting in several techniques for the production of nanoparticles, such as methods of chemical synthesis. Among the various existing methods, the Pechini method has been used to obtain nanoparticles of titanium dioxide (TiO2). Thus, this work aims to synthesize and characterize nanoparticles of TiO2 obtained by this method. The technique constitutes in the reaction between citric acid with titanium isopropoxide, resulting as the product the titanium citrate. With the addition of the ethylene glycol polymerization occurs, resulting in a polymeric resin. At the end of the process, the resin is calcined to remove organic matter, creating nanoparticles of TiO2. The resulting powders were characterized by thermogravimetric analysis (TGA) and thermal differential analysis (DTA), X-ray diffraction, absorption spectrophotometry in the infrared, method of adsorption nitrogen / helium (BET method) and scanning electron microscopy. The results obtained in the characterization techniques showed that the Pechini method is promising in obtaining nanosized TiO2.
Knowledge of particle concentration is of extreme importance for the settling
phenomenon. For well-diluted suspensions the solids concentration can be measured by
sampling techniques. However, the use of such a technique for more concentrated suspension
does not lead to good results. Knowledge of concentration distribution in sediments formed
by decantation of aqueous suspensions inside a vertical vessel is fundamental for the
evaluation of performance of some pieces of equipment such as continuous thickeners. In this
work, the phenomenon of batch settling of aqueous suspensions of calcium carbonate was
studied by using a nondestructive technique based upon the measurement of gamma-ray
attenuation when the radiation beam goes through the physical medium as a function of the
local concentration in several vertical positions of the vessel, and the sampling of suspension
by aliquots is not necessary. The main objective of this work is to evaluate the use of gammaray
attenuation technique for achieving concentration distributions in the phenomenon of
batch settling as well as curves of iso-concentrations.
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