Fingerprints are unique to each individual, contributing to human identification in forensic cases. The powder technique being widely used is considered one of the most important in latent fingermarks analysis. In this sense, the present work aimed to synthesize 1-thiocarbamoyl-4,5-dihydro-1H-pyrazoles and apply them as powder agents to develop latent fingermarks. The compounds were prepared from an effective and green synthesis via the condensation of chalcones with thiosemicarbazide in ethanol under microwave irradiation. Pyrazoles were tested and compared with a standard white powder (Sirchie®) on glass surfaces using sebaceous and natural fingermarks so that molecule 2c has been shown to be more promising providing image clarity. The derivatives of pyrazoles were promising as an alternative latent fingermark, presenting high quality images for fingermarks, proving to be a great tool for forensic sciences.

Pb/Ti, Sn and Mg-based nanocomposite materials were prepared by the high-energy mechanical milling of commercial powders. The surface of these ceramic compounds was strongly influenced by the doping, diameter of the milling spheres and time of the mechanical milling (amorphization process). Such milling leads to the formation of nanocrystalline materials. The mechanical processing parameters of these compounds were investigated through Brunauer, Emmett and Teller isotherms, wide angle X-ray diffraction, transmission electron microscopy and CO2 adsorption.

Neste trabalho foi investigada a preparação de carbonos ativados através da pirólise de composições elastoméricas provenientes de resíduos de bandas de rodagem de pneus de automóveis. O material foi processado nas temperaturas de 500, 620 e 700 °C, em atmosfera de N2, utilizando-se o hidróxido de potássio como agente ativador. Os produtos resultantes foram caracterizados pela fisisorção de N2 a 77 K, através de isotermas de Brunauer, Emmet e Teller e por microscopia eletrônica de varredura. Esses carbonos ativados apresentam estruturas típicas de sólidos mesoporosos e a temperatura de pirólise tem grande influência na área específica e distribuição de volume de poros. O carbono ativado obtido a 700 °C apresentou maior área específica e estrutura porosa compacta. Esse material apresenta melhor desempenho frente à adsorção de azul de metileno, removendo até 1,0 x 10-1 g de corante por grama de carbono utilizado, em tempos inferiores a 300 s.

In this work, the preparation of activated carbons through the pyrolysis of elastomers, arising from car threads of tire waste, was investigated. The material was processed at 500, 620 and 700 °C, under N2 atmosphere, by using potassium hydroxide as activating agent. The resulting products were characterized by physisorption of N2 at 77 K, through Brunauer, Emmet and Teller isotherms, and scanning electron microscopy. The carbons obtained display a characteristic structure of mesoporous materials and the pyrolysis temperature has strong influence on the specific area and porous volume distribution. The activated carbon obtained at 700 °C has high specific area and compact structure. It exhibited high performance for adsorption of methylene blue solution, removing 1.1 x 10-1 g of the dye per gram of carbon in less than 300 s.

Neste trabalho é apresentada a reação de condensação aldólica entre metanol e acetona promovida por nanopartículas de dióxido de estanho, não dopadas e dopadas com as terras raras Ce e Y. Diversas condições de relação molar metanol/acetona foram avaliadas, objetivando a obtenção com elevada seletividade do composto a, b-insaturado, metil vinil cetona. As nanopartículas foram preparadas empregando-se o método dos precursores poliméricos. As amostras foram caracterizadas por meio de adsorção de N2 para determinação de área superficial específica (BET), difração de raios X (DRX), adsorção química de CO2, espectroscopia de fotoelétrons (XPS) e microscopia eletrônica de transmissão (MET). O comportamento catalítico observado para as amostras de SnO2 sugere que a relação molar metanol/acetona e a dopagem com as terras raras desempenham um papel importante na atividade catalítica do material e na seletividade aos produtos reacionais. Os resultados de DRX e XPS apontam para a formação de uma camada de segregação, para as amostras dopadas, devido ao tratamento térmico imposto. Essa camada de segregação afeta diretamente o comportamento catalítico do material frente à reação de condensação.

Aldol condensation between methanol and acetone, catalyzed by undoped and rare earths (Ce and Y) doped tin oxide nanoparticles is presented. Several methanol/acetone molar ratio conditions were evaluated aiming to produce methyl vinyl ketone as the main product. The undoped and doped ultrafine nanoparticles of tin oxide were prepared using the polymeric precursor method. The characterization was carried out by means of N2 adsorption (BET), X-ray diffraction (XRD), CO2 chemisorption, X-ray photoemission spectroscopy (XPS) and transmission electron microscopy (TEM). The catalytic behavior observed for SnO2 samples suggests that the methanol/acetone molar ratio and Ce and Y doping play an important role in the catalytic activity and in the product selectivity. The results from XRD and XPS pointed to the de-mixing process for the doped samples, due to the heat-treatment. This segregation layer contributes to the observed change in the catalytic behavior.

Ca1-xLa xTiO3 powders were prepared by the polymeric precursor method. X-ray diffraction (XRD), FT-Raman spectroscopy, transmission electron microscopy (TEM), and N2 and CO2 adsorption were used for the microstructural and surface characterization of the powders. Room temperature photoluminescence (PL) was observed in Ca1-xLa xTiO3 amorphous particles. The PL intensity of these powders was found to be dependent on the lanthanum molar concentration.

The carbon dioxide reforming of methane was carried out over nickel catalysts supported on the gamma-Al2O3/CeO2 system prepared by wet impregnation. With the increase of the CeO2 weight in the catalyst, a higher stability was observed in the catalytic activity, together with an excellent resistance to carbon deposition and a better Ni dispersion. The catalysts were characterized by means of surface area measurements, TPR, H2 chemisorption, XRD, SEM, EDX, XPS and TEM. An interaction between Ni and CeO2 was observed to the Ni/CeO2 sample after activation in a H2 atmosphere above 300 ºC. Such behavior has a significantly influence on the catalytic activity.

Nickel nanoparticles supported on amorphous silica ceramic matrix were synthesized by the polymeric precursor method. The nanostructure was characterized by NMR, BET, XRD, SEM, TEM, and flame atomic absorption spectrometry techniques. It was observed a dependence of the crystallite size on the thermal annealing, under a N2 atmosphere. The materials presented a high catalytic activity and selectivity upon the beta-pinene hydrogenation reaction. The magnetic hystereses were also correlated with the morphology of the processed material.