Utilização de turfa para remoção de metais potencialmente tóxicos de uma empresa recicladora de plásticos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Eletro-oxidação de metanol e etanol sobre PtAu/C em meio alcalino

The development of electrocatalysts for the oxidation of methanol and ethanol is very important, because these alcohols may be used in the anode fuel cells which convert chemical energy directly into electrical energy with high efficiency, cleanly and with low noise. Thus, this study reports to the synthesis of nanocatalysts of PtAu supported on carbon by microemulsion method. The physical characterization of these catalysts is performed through the techniques of X-ray diffraction and transmission electron microscopy. The catalytic activity of the prepared materials was studied using conventional electrochemical techniques and also the technique of spectro-electrochemical in situ FTIR, which allows identification of intermediates and products of the reactions. From the x-ray diffraction, it was observed that the thermal treatment applied to catalysts favored incorporation of Au into the crystal lattice of Pt,that is, increased the formation of PtAu alloy. Micrographs indicated particle size about 3 nm to materials not heat treated and 9 nm to materials subjected to thermal treatment (heating at 150 ° C for 1h and 30 min in argon atmosphere). Current density oxidation of methanol on PtAu / C were superior to pure platinum. Spectroscopic results indicated the presence of formate in solution in 50:50 and the composition showed bands for CO2, indicating complete oxidation, in lower potential. During ethanol oxidation on the catalyst PtAu, the main product formed was acetate, product of incomplete oxidation. The good performance for methanol oxidation can be attributed to large amounts of oxygen species adsorbed on the catalyst surface, or an electronic effect.

Filmes híbridos PMMA-siloxano modificados com nanotubos de carbono para proteção de materiais metálicos contra corrosão

Using the sol-gel process, organic-inorganic hybrid coatings were synthesized by incorporation of different concentrations of functionalized carbon nanotubes, to improve their mechanical strength and thermal resistance without changing its passivation character. The siloxane-PMMA hybrids were prepared by radical polymerization of methyl methacrylate (MMA) with 3-methacryloxipropiltrimethoxisilane (MPTS) using the thermal initiator benzoyl peroxide (BPO), followed by acid catalyzed hydrolysis and condensation of tetraethoxysilane (TEOS). The analysis of pristine and functionalized carbon nanotubes was carried out using Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy and Raman Spectroscopy. Structural analysis of hybrids was performed by Nuclear Magnetic Resonance, Atomic Force Microscopy and Raman Spectroscopy. For analysis of mechanical strength and thermal stability were performed mechanical compression tests and thermogravimetric analysis, respectively. Electrochemical Impedance Spectroscopy was used to evaluate the corrosion resistance in saline environment. The results showed an effective functionalization of carbon nanotubes with carboxyl groups and conservation of its structure. The hybrids showed high siloxane network connectivity and roughness of approximately 0.3 nm. The incorporation of carbon nanotubes in the hybrid matrix did not change significantly their thermal stability. Samples containing carbon nanotubes exhibit good corrosion resistance (on the order of MΩ in saline environment), but the lack of complete dispersion of carbon nanotubes in the hybrid, resulted in a loss of mechanical and corrosion resistance compared to hybrid matrix.

Ciência e arte: vida-(e)-morte encenada(s)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeito das fibras alimentares como substitutos de gordura em hambúrguer de carne bovina e paio

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Caracterização dos resíduos do processamento de mandioca para produção de bioetanol

Aiming to get the best economic advantage in ethanol production from cassava roots, this study presented a physiochemical characterization from two different types of solid waste in two types of processing of the raw materials in manufacturing ethanol. The processing of cassava roots begins with the disintegration and washing the roots with the addition of 20% more water to obtain a pulp which was treated and stirred in the reactor while adding enzyme α-amylase at a temperature of 90°C for 2 hours. Then we performed a pH adjustment while lowering the temperature to 60 ° C with the addition of the enzyme amiloglucosidase and then stirring for 14 hours. The hydrolyzate obtained was the source of two types of waste which are: i) Solid residue obtained after filtration of the hydrolyatze and ii) Solid waste obtained from filtering wine after alcoholic fermentation of the hydrolyzate with the addition of a dried yeast strain Y-940 manufactured by MAURI OF BRAZIL SA (2%) at a temperature of 25º C. The results of the laboratory analysis showed that the byproducts derived from the hydrolysis and fermentation showed very similar chemical compositions. With levels between 39 and 41% fiber, 0.5% lipids, 20 and 30% carbohydrates, protein 0.5 and 1.50, 6 and 8% acidity, and 20 and 30% soluble solids.