Prepara����o de membranas de acetato de celulose organomodificadas para adsor����o de ��ons C(II), Cd(II), Mn(II) e Ni(II)

Cu(II), Cd(II), Mn(II) AND Ni(II). Cellulose acetate polymeric membranes had been prepared by a procedure of two steps, combining the method of phase inversion and the technique of hydrolysis-deposition. The first step was the preparation of the membrane, and together was organomodified with tetraethylortosilicate and 3-aminopropyltrietoxysilane. Parameters that exert influence in the complexation of the metallic ion, as pH, time of complexation, metal concentration, had been studied in laboratory using tests of metal removal. The membranes had presented resistance mechanics and reactivity to cations, being able to be an alternative for the removal, daily pay-concentration or in the study of the lability of metals complexed.

EStudo fundamental da intera����o de nanopart��culas met��licas com ��ons terras raras em vidros e vitrocer��micas para aplica����es na regi��o do infravermelho

P��s-gradua����o em Qu��mica - IQ

Fotocromismo e luminesc��ncia de compostos a base de tungst��nio e ��ons terras raras trivalentes via s��ntese hidrot��rmica

P��s-gradua����o em Qu��mica - IQ

Espectroscopia de imped��ncia eletroqu��mica da biodissolu����o da calcopirita na presen��a de ��ons ferrosos

P��s-gradua����o em Qu��mica - IQ

Caracteriza����o t��rmica e f��sico-qu��mica do sistema argila-8-hidroxiquinolina na remo����o de ��ons Fe(III), Ni(II) e Co(II)

Coordena����o de Aperfei��oamento de Pessoal de N��vel Superior (CAPES)

X-ray photoelectron spectroscopy study on sintered Pb1-xLaxTiO3 ferroelectric ceramics

The Pb1-xLaxTiO3 sintered ferroelectric ceramics with x equal to 0, 0.10, 0.15, 0.20, and 0.30 were studied by X-ray photoelectron spectroscopy (XPS). The binding energy of the Ti 2p lines is consistent with only one chemical state, Ti4+. on the other hand, in the case of Pb 4f and 0 Is XPS spectra, apart from the main peaks attributed to the lattice ions, minor peaks related to the surface states were also observed. The presence of Pb-0 state on the surface of all samples was due to the reduction of lead ions caused by the preferential removal of the oxygen ions after sputtering. The non observation of Ti3+ ions confirms that the mechanism of charge compensation that should occurs owing to the substitution of Ph2+ by La3+ is due to the preferential formation of Pb site vacancies, and not to a reduction from Ti4+ to Ti3+ states. Within the limits of the present experiment, there is no evidence of the existence of non-equivalent Pb, Ti, and La sites as the Pb1-xLaxTiO3 ceramic changes from a normal to a relaxor ferroelectric state. (c) 2006 Elsevier B.V. All rights reserved.

S��ntese, caracteriza����o e avalia����o da atividade biol��gica de metalof��rmacos de sulindaco com ��ons lantan��deos (III) no estado s��lido

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Modifica����o de eletrodos de carbono v��treo e nanotubos de Ti/TiO2 com aspirinato de cobre (II) para detec����o eletroqu��mica e redu����o fotoeletrocatal��tica de ��ons nitrito

Conselho Nacional de Desenvolvimento Cient��fico e Tecnol��gico (CNPq)

Íons terras raras inseridos em matrizes polim��ricas de germ��nio e enxofre para prepara����o de materiais com propriedades ��pticas

P��s-gradua����o em Qu��mica - IQ

Metalosupramol��culas discretas e Metal Organic Frameworks (MOFs) baseados em ��ons lantan��deos: design, s��ntese, caracteriza����o e propriedades

Conselho Nacional de Desenvolvimento Cient��fico e Tecnol��gico (CNPq)

Estudo da ativa����o da superf��cie de alum��nio por ��ons de merc��rio e forma����o do am��lgama Hg-Al: identifica����o do produto e cin��tica de rea����o

The activation of aluminum surface has the most various purposes as for example the search for the surface activation mechanism and the corrosion products by mercury ions. The objective of this work is to study the reactivity of the surface of aluminum metal when activated by mercury ions (Hg2+), with the consequent formation of an Al-Hg amalgam. Results demonstrate that the kinetics of the reaction, by measuring the mass change with time of the corrosion product formed between Al and Hg, and analysis by infrared spectroscopy (IR) that the product of the reaction between the amalgam, located on the surface, and the atmospheric oxygen is Al2O3 (aluminum hydroxide). The results also indicate that the kinetics of the reaction between the amalgam (Hg-Al) and atmospheric oxygen is of first order and reach a region where there is no more formation of product

Estabiliza����o da fase perovskita e propriedades estruturais de filmes finos relaxores do sistema PLZT

P��s-gradua����o em Ci��ncia dos Materiais - FEIS

NANOSCALE ELECTROCHEMISTRY BY IN-SITU TRANSMISSION ELECTRON MICROSCOPY

Nanoscale research in energy storage has recently focused on investigating the properties of nanostructures in order to increase energy density, power rate, and capacity. To better understand the intrinsic properties of nanomaterials, a new and advanced in situ system was designed that allows atomic scale observation of materials under external fields. A special holder equipped with a scanning tunneling microscopy (STM) probe inside a transmission electron microscopy (TEM) system was used to perform the in situ studies on mechanical, electrical, and electrochemical properties of nanomaterials. The nanostructures of titanium dioxide (TiO2) nanotubes are characterized by electron imaging, diffraction, and chemical analysis techniques inside TEM. TiO2 nanotube is one of the candidates as anode materials for lithium ion batteries. It is necessary to study their morphological, mechanical, electrical, and electrochemical properties at atomic level. The synthesis of TiO2 nanotubes showed that the aspect ratio of TiO2 could be controlled by processing parameters, such as anodization time and voltage. Ammonium hydroxide (NH4OH) treated TiO2 nanotubes showed unexpected instability. Observation revealed the nanotubes were disintegrated into nanoparticles and the tubular morphology was vanished after annealing. The nitrogen compounds incorporated in surface defects weaken the nanotube and result in the collapse of nanotube into nanoparticles during phase transformation. Next, the electrical and mechanical properties of TiO2 nanotubes were studied by in situ TEM system. Phase transformation of anatase TiO2 nanotubes into rutile nanoparticles was studied by in situ Joule heating. The results showed that single anatase TiO2 nanotubes broke into ultrafine small anatase nanoparticles. On further increasing the bias, the nanoclusters of anatase particles became prone to a solid state reaction and were grown into stable large rutile nanoparticles. The relationship between mechanical and electrical properties of TiO2 nanotubes was also investigated. Initially, both anatase and amorphous TiO2 nanotubes were characterized by using I-V test to demonstrate the semiconductor properties. The observation of mechanical bending on TiO2 nanotubes revealed that the conductivity would increase when bending deformation happened. The defects on the nanotubes created by deformation helped electron transportation to increase the conductivity. Lastly, the electrochemical properties of amorphous TiO2 nanotubes were characterized by in situ TEM system. The direct chemical and imaging evidence of lithium-induced atomic ordering in amorphous TiO2 nanotubes was studied. The results indicated that the lithiation started with the valance reduction of Ti4+ to Ti3+ leading to a LixTiO2 intercalation compound. The continued intercalation of Li ions in TiO2 nanotubes triggered an amorphous to crystalline phase transformation. The crystals were formed as nano islands and identified to be Li2Ti2O4 with cubic structure (a = 8.375 ��). This phase transformation is associated with local inhomogeneities in Li distribution. Based on these observations, a new reaction mechanism is proposed to explain the first cycle lithiation behavior in amorphous TiO2 nanotubes.