Obtenção e caracterização do sistema compósito alginato de sódio-dióxido de titânio em formas de pó e de membrana

The alginates are copolymers of 1→4-linked β-D-mannuronic acid (M) and α-Lguluronic acid (G) residues that are arranjed in a block structure along a linear chain. Titanium dioxide, TiO2, is a ceramic material and can exist in three distinct crystallography forms: anatase, brookite and rutile. composites of organic and inorganic materials have better properties than the components alone. Thus, this study aims to synthesize, characterize and analyze the composite NaAlg-TiO2 in the form of powder and film. The synthesis of composite powders was performed using the sol-gel process and obtain the composite film was performed using the slow evaporation process, then the composites were analyzed by infrared spectroscopy, fluorescence x ray, thermal analysis, attenuated total reflection (ATR), x ray diffraction and impedance spectroscopy. The X ray diffraction patterns of composite powders show that with increasing calcination temperature, there were no complete transition of rutile-anatase crystalline phase, since at all temperatures studied (300, 500, 700, 900 and 1100ºC) were observed peaks of anatase phase. Thermal analysis shows that at 400°C caused the decomposition of sodium alginate in sodium carbonate and above 600°C, we observe an exothermic peak related to the decomposition of sodium carbonate and in the presence of titanium dioxide becomes sodium titanate. The XRD results confirm the formation of sodium carbonate at 700ºC and the formation sodium titanate in the temperature range 900-1100ºC. The sodium titanate influenced the electrical properties of the material, because with increasing temperature there was a decrease in conductivity, probably due to the creation of Ti vacancies, since the sodium can induce the reduction of surface Ti4+ ions into Ti3+ species. The infrared spectra of the composites in the form of powder and film showed a small shift in the bands compared to the spectrum of pure alginate, indicating that these shifts, even small ones, have evidence of miscibility between the polymer and ceramic material

Avaliação da poatencialidade da perlita natural e expandida na adsorção de metais

The contamination by metal ions has been occurring for decades through the introduction of liquid effluent not treated, mainly from industrial activities, rivers and lakes, affecting water quality. For that the effluent can be disposed in water bodies, environmental standards require that they be adequately addressed, so that the concentration of metals does not exceed the limits of standard conditions of release in the receptor. Several methods for wastewater treatment have been reported in the literature, but many of them are high cost and low efficiency. The adsorption process has been used as effective for removal of metal ions. This paper presents studies to evaluate the potential of perlite as an adsorbent for removing metals in model solution. Perlite, in its natural form (NP) and expanded (EP), was characterized by X-ray fluorescence, X-ray diffraction, surface area analysis using nitrogen adsorption (BET method), scanning electron microscopy and Fourier transform infrared spectroscopy. The physical characteristic and chemical composition of the material presented were appropriate for the study of adsorption. Adsorption experiments by the method of finite bath for model solutions of metal ions Cr3+, Cu2+, Mn2+ and Ni2+ were carried out in order to study the effect of pH, mass of the adsorbent and the contact time on removal of ions in solution. The results showed that perlite has good adsorption capacity. The NP has higher adsorption capacity (mg g-1) than the EP. According to the values of the constant of Langmuir qm (mg g-1), the maximum capacity of the monolayer was obtained and in terms of proportion of mass, we found the following order experimental adsorption: Cr3+ (2.194 mg g- 1) > Ni2+ (0.585 mg g-1) > Mn2+ (0.515 mg g-1) > Cu2+ (0.513 mg g-1) and Cr3+ (1.934 mg g-1)> Ni2+ (0.514 mg g-1) > Cu2+ (0.421 mg g-1) > Mn2+ (0.364 mg g-1) on the NP and EP, respectively. The experimental data were best fitted the Langmuir model compared to Freundlich for Cu2+, Mn2+ and Ni2+. However, for the Cr3+, both models fit the experimental data

Caracterização e aplicação de vermicultura natural e quimicamente modificada na adsorção de azul de metileno

Chemical modification of clays has been extremely studied in the search for improvements of their properties for use in various areas, such as in combating pollution by industrial effluents and dyes. In this work, the vermiculite was chemically modified in two ways, characterized and evaluated the adsorption of methylene blue dye. First was changed with the addition of a surfactant (hexadecyltrimethylammonium bromide, BHTA) making it an organophilic clay and then by adding an acid (HCl) by acid activation. Some analyzes were performed as X-ray fluorescence (FRX), X-ray diffraction (DRX), adsorption isotherms of methylene blue dye, infrared (FTIR) , scanning electron microscopy (SEM), thermal gravimetric analysis and spectroscopy energy dispersive (EDS). Analysis by FRX of natural vermiculite indicates that addition of silicon and aluminum, clay presents in its structure the magnesium, calcium and potassium with 16 % organic matter cations. The DRX analyzes indicated that the organic vermiculite was an insertion of the surfactant in the space between the lamellae, vermiculite and acid partial destruction of the structure with loss of crystallinity. The adsorption isotherms of methylene blue showed that there was a significant improvement in the removal of dye to the vermiculite with the addition of cationic surfactant hexadecyltrimethylammonium bromide and treatment with acid using HCl 2 mol/L. In acid vermiculites subsequently treated with surfactant, the adsorption capacity increased with respect to natural vermiculite, however was much lower compared vermiculite modified with acid and surfactant separately. Only the acidic vermiculite treated with surfactant adjusted to the Langmuir model. As in the infrared spectrometry proved the characteristics of natural vermiculite. In the organic vermiculite was observed the appearance of characteristic bands of CH3, CH2, and (CH3)4N. Already on acid vermiculite, it was realized a partial destruction with decreasing intensity of the characteristic band of vermiculite that is between 1074 and 952 cm-1. In the SEM analysis, it was observed that there was partial destruction to the acid treatment and a cluster is noted between the blades caused by the presence of the surfactant. The TG shows that the higher mass loss occurs at the beginning of the heating caused by the elimination of water absorbed on the surface between layers. In the organic vermiculite also observed a loss of mass between 150 and 300 °C caused decomposition of the alkylammonium molecules (surfactants)

Caracterização estrutural de Perovskitas Lax-1AxCoO3 (x=0 e 0,2) ,dopadas com cálcio e bario, por espectroscopia de absorção de raios X (XAS).

In this work, the structures of LaCoO3, La0,8Ba0,2CoO3 and La0,8Ca0,2CoO3 perovskites were characterized as a function of temperature (LaCoO3 structure being analyzed only at room temperature). The characterization of these materials were made by X-Ray Absorption Spectroscopy (XAS), in the cobalt K-edge, taking into account the correlated Einstein model X-ray absorption fine structure (EXAFS). The first part of the absorption spectrum corresponded the X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). These materials were prepared by the combustion method. The combustion products were calcinated at 900 0C, for 6 hours in air. Noted that the sample LaCoO3 at room temperature and samples doped with Calcium and Barium in the temperature range of 50 K to 298 K showed greater distortion to monoclinic symmetry with space group I2/a. However, the sample doped with barium at the temperatures 50 K, 220 K, and 260 K showed a slight distortion to rhombohedral symmetry with space group R-3c. The La0,8Ca0, 2CoO3 structure was few sensitive to temperature variation, showing a higher local distortion in the octahedron and a higher local thermal disorder. These interpretations were in agreement with the information electronic structural on the XANES region and geometric in the EXAFS region

Um novo método para quantificar mercúrio orgânico (Hg orgânico) empregando a espectrometria de fluorescência atômica do vapor frio

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Espectroscopia de impedância no laboratório de ensino

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Síntese, caracterização e estudos de interação de um análogo da antitoxina CcdA empregando fluorescência no estado estacionário

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Caracterização e estudo da corrosão do amálgama dentário Dispersalloy por meio das técnicas de polarização potenciodinâmica e espectroscopia de impedância

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Aplicação e avanços da espectroscopia de luminescência em análises farmacêuticas

This paper provides a review on the latest advances and applications of the luminescence spectroscopy for the development of pharmaceuticals analyses methods, basically based on the photo- and chemiluminescence. The different forms of the drugs determination on pharmaceuticals through the fluorescence and chemiluminescence are discussed. The analyses include the drugs native fluorescence (liquid and solid-phases); the fluorescence from the oxidizing or reducing forms of the drug; the fluorescence from the chemical derivatization and their photochemistry and hydrolysis reactions. The quenching of luminescence and chemiluminescence generation for the pharmaceutical quantification are also shown. Finally, the trends and future perspectives of the luminescence spectroscopy in the field of the pharmaceutical research are discussed.

Investigação por espectroscopia Mössbauer de compostos de ferro(0) contendo dissulfeto de carbono

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Espectroscopia óptica de vidros fluoroindatos dopados com íons Er3+ e Yb3+

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Extração por fluido supercrítico de alguns inseticidas carbamatos em amostras de batata, com determinação por HPLC/fluorescência e confirmação por HPLC/espectrometria de massas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Espectroscopia de impedância eletroquímica aplicada ao estudo das reações heterogêneas em ânodos dimensionalmente estáveis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Fotopedologia, espectroscopia e sistema de informação geográfica na caracterização de solos desenvolvidos do Grupo Barreiras no Amapá

O presente trabalho utilizou ferramentas de sensoriamento remoto e sistema de informação geográfica, aliadas às informações espectrais do solo e quantitativas e qualitativas do relevo, para a caracterização e discriminação das classes de solos desenvolvidos do Grupo Barreiras na região do município de Porto Grande, Amapá. Após o mapeamento semidetalhado de solos, realizou-se a caracterização pontual das amostras dos perfis por meio de espectroscopia de visível e infravermelho (400-2500 nm), e a análise espacial das redes de drenagem e relevo a partir de fotos aéreas e imagens de radar. As informações quantitativas do relevo foram mais eficientes na caracterização e discriminação dos solos estudados do que as qualitativas, enquanto as informações espectrais permitiram caracterizar os solos em nível pontual. Métodos espaciais utilizando redes de drenagem e relevo e métodos espectrais utilizando amostras pontuais complementam-se na caracterização e discriminação de solos na paisagem.

Correlação entre métodos tradicionais e espectroscopia de ultra-som na determinação de características físico-químicas do leite

Compararam-se a espectroscopia de ultra-som (US) e os métodos tradicionais (MT) utilizados para a determinação de características físico-químicas do leite e estimaram-se as correlações entre esses métodos e suas acurácias. As características densidade, extrato seco desengordurado (ESD), teor de proteínas e teor de gordura foram determinadas em 65 amostras de leite cru por ambos os métodos. As densidades médias determinadas pelo US e pelos MT não diferiram entre si (P=0,14), e a correlação encontrada entre os dois métodos para a determinação da densidade não foi significativa (P= 0,08). Os teores médios de ESD, proteína e gordura encontrados pelo US e pelos MT foram diferentes (P=0,04, P<0,0001 e P<0,0001, respectivamente), as correlações entre os dois métodos utilizados para a análise dessas características foram positivas e significativas (r=0,0109, r=0,0007, r= <0,0001, respectivamente) e as acurácias dos métodos para essas determinações foram de 0,160, 0,062 e 0,145, respectivamente. Foi determinada a equação de regressão linear, que associa o teor de gordura obtido no método de espectroscopia de ultra-som ao do método butirométrico, que apresentou coeficiente de determinação de 0,5936.