Termogravimetria: um novo enfoque para a clássica determinação de cálcio em cascas de ovos

The use of thermoanalytical data in sample preparation is described as a tool to catch the students' attention to some details that can simplify both the analysis and the analytical procedure. In this case, the thermal decomposition of eggshells was first investigated by thermogravimetry (TGA). Although the classical procedures suggest long exposure to high temperatures, the TGA data showed that the decomposition of organic matter takes place immediately when the sample is heated up to 800 °C under air atmosphere. After decomposition, the calcium content was determined by flame atomic emission photometry and compared with the results obtained using classical volumetric titration with EDTA.

Determinação do teor de cálcio em comprimido à base de lactato de cálcio utilizado no tratamento da osteoporose

The present study utilized thermogravimetry (TG) and optical emission spectrometry with inductively coupled plasma (ICP/OES) to determine the amount of calcium in calcium lactate tablets used in the treatment of osteoporosis. Thermogravimetry results indicated that the decomposition temperature of CaCO3 occurred at 603.9 and 609.4 ºC in the samples of calcium lactate and tablets, respectively. The calcium content obtained by TG for the tablets sample showed a similar result to that disclosed by ICP-OES, indicating a value of 8.93% for both techniques.

Síntese e impregnação de peneiras moleculares Fe MCM-41 derivada de sílica da casca do arroz

The mesoporous molecular sieves of the MCM-41 and FeMCM-41 type are considered promissory as support for metals used as catalysts in oil-based materials refine processes and as adsorbents for environmental protection proposes. In this work MCM-41 and FeMCM41 were synthesized using rice husk ash - RHA as alternative to the conventional silica source. Hydrothermal synthesis was the method chosen to prepare the materials. Pre-defined synthesis parameters were 100°C for 168 hours, later the precursor was calcinated at 550°C for 2 hours under nitrogen and air flow. The sieves containing different proportions of iron were produced by two routes: introduction of iron salt direct synthesis; and a modification post synthesis consisting in iron salt 1 % and 5% impregnation in the material followed by thermal decomposition. The molecular sieves were characterized by X ray diffraction XRD, Fourier transform infrared spectroscopy FT-IR, X ray fluorescence spectroscopy XFR, scanning electronic microscopy SEM, specific surface area using the BET method, Termogravimetry TG. The kinetic model of Flynn Wall was used with the aim of determining the apparent activation energy of the surfactant remove (CTMABr) in the MCM- 41 porous. The analysis made possible the morphology characterization, identifying the presence of hexagonal structure typical for mesoporous materials, as well as observation of the MCM41 and iron of characteristic bands.

Preparação e caracterização do complexo sólido de estanho(II)-EDTA e influência do tratamento térmico sobre a morfologia do resíduo SnO2

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Características estruturais de géis de sílica preaparados a partir da sonohidrólise do tetraetilortosilicato com adições de álcool polivinílico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Propriedades estruturais de géis de sílica preparados a partir da sonohidrólise do tetraetilortosilicato com adições de dimetilformamida

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Propriedades nanoestruturais de géis de sílica preparados com adiçoes de surfactante anionico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Síntese de aerogéis e xerogéis de sílica com troca de solvente e secagem a pressão ambiente

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Obtenção de fotocatalisadores magnéticos a partir de resíduos industriais e TiO2 para a degradação de contaminantes orgânicos

In this work, magnetic photocatalysts were synthesized containing differents levels of TiO2 (40, 60 e 80%) supported at the supporter of C/LV, forming the photocatalysts 40, 60, 80Ti/C/LV, using tar pitch as carbon (C) source and red mud (LV) as iron source. The prepared magnetic photocatalysts and TiO2 were used to degrade the Remazol Black textile dye (PR5) and the organic material present in samples of a textile dye effluent. The characterization of photocatalysts by Raman, X-Ray Diffraction, Transmission Electron Micoscope and Scanning, Energy Dispersive X-ray Spectrometry, Termogravimetry and Elemental Analysis, confirms the presence of carbon and magnetite in support C/LV and the presence of TiO2 in prepared photocatalysts. The photocatalytic reactions with TiO2 were analyzed by different experimental conditions, such as: mass of TiO2 (30-240 mg), solution pH (2-10), light intensity (0.871 and 1.20 mWcm-2), type of radiation (UV and sunlight-1.420 mWcm-2), radiation incidence area (44.2 to 143.1 cm2) and dissolved oxygen (OD, 1.9 and 7.6 mg L- 1). Results showed that reactions with the following conditions: 220 mg of TiO2, pH 10, solar radiation, 7.6 mg L-1 of OD and an incidence area of radiation of 143.1 cm2 showed the best results for degradation of PR5 dye. Photocatalytic reactions with magnetic photocatalysts for degrading PR5 shows that efficiency increases with TiO2 content in the C/LV support, where, above 60% of TiO2, there was not significant increase in reaction velocity. In addition, solar radiation has proved to be advantageous for photocatalytic reactions. In order to verify the presence of a non-magnetic fraction in the photocatalyst 60Ti/C/LV0, magnetic separation was proceeded. The characterizations of the magnetic (FM) and nonmagnetic (NMF) fraction confirmed that about 25% of TiO2 did not fixed in 60Ti/C/LV photocatalyst. Results of photocatalytic reactions with FM and FNM showed that both phases have photocatalytic activity for degradation of PR5. The reactions executed for the degradation of organic matter present in the actual sample of textile effluent showed that TiO2 and magnetic photocatalyst 60Ti/C/ LV have better results for color removal (85 to 35%), soluble solids ( 11 and 3%), DQO (90 and 86%) and turbidity (94 and 11%) than the treatment done by the textile industry. Sedimentation kinetics tests in presence of a magnet showed that photocatalysts are separated faster from aqueous environment than pure TiO2. Obtained results showed that magnetic photocatalysts have excellent photocatalytic activity and can be separated from the reaction environment on a simple and quick way when a magnetic field is applied.

Estudo termoanalítico e eletroquímico das reações em estado sólido na interfase metálica dos sistemas Pt-Rh/Hg, empregando a liga de composição Pt-Rh 80:20% (m/m)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Síntese, caracterização e estudo do comportamento térmico dos 2-metoxibenzoatos de Mn(II), Co(II), Ni(II), Cu(II) e Zn(II) no estado sólido

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Identificação de pigmentos em artefatos arqueológicos via espectroscopia Micro-Raman

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

Síntese, caracterização, estudo termoanalítico e cinético do 2-metoxibenzalpiruvato de 'MN', 'FE', 'CO', 'NI', 'CU', e 'ZN', no estado sólido

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Caracterização vibracional e térmica de compósitos de LLDPES modificados e sílica (OU) Caracterização vibracional e térmica de compósitos de lldpe\'s funcionallzados e sílica de superfície modificada

Compósitos de polímeros de polietileno linear de baixa densidade (LLDPE) possuem baixo desempenho mecânico devido principalmente à sua fraca interação, intermolecular, entre a cadeia polimérica e a carga. Uma maneira de minimizar esse baixo desempenho mecânico se faz com a mudança da estrutura química da poliolefina com a inserção de um grupo polar a sua cadeia, ou seja, faz-se a funcionalização das poliolefinas. O sistema de funcionalização adotado foi o processamento reativo, no qual foi utilizado para este sistema de processamento o misturador de dupla rosca acoplado a um reâmetro de torque. Neste trabalho, os grupos polares inseridos à cadeia dos polímeros de LLDPE\'s de copolímeros 1-buteno e 1-octeno (LLDPE-but e LLDPE-oct) foram o anidrido maléico (AM) e o anidrido tetrahidroftálico (ATF). Para a confecção dos compósitos foram utilizadas as cargas de microesferas de sílica modificada, no qual foi inserido compostos silanados em sua superfície (3-aminopropilsilano - APS - e trimetoxiclorosilano TMCISi) para estudo de interação com as poliolefinas funcionalizadas. Neste trabalho foram realizados ensaios de caracterização térmica, vibracional além de análises de torque do polímero fundido, análises do grau de reticulação e ensaios mecânicos de tração por elongação. Na caracterização térmica foram utilizadas as técnicas: termogravimetria (TG) e calorimetria exploratória diferencial (DSC). Na caracterização vibracional utilizou-se a espectroscopia fotoacústica no infravermelho (PAS-IR) e a espectroscopia de espalhamento Raman. Pela técnica PAS-IR foi possível comprovar a inserção dos anidridos à cadeia das poliolefinas assim como foi possível verificar a interação entre o polímero funcionalizado e a carga. Pelas técnicas térmicas de DSC e TG foi possível verificar mudanças das propriedades do compósito frente aos polímeros originais ou funcionalizados. Os ensaios mecânicos comprovaram que os compósitos de polímeros funcionalizados possuem maior elongação e tensão à ruptura comparada aos compósitos dos LLDPE\'s não funcionalizados

Síntese e impregnação de peneiras moleculares Fe MCM-41 derivada de sílica da casca do arroz

The mesoporous molecular sieves of the MCM-41 and FeMCM-41 type are considered promissory as support for metals used as catalysts in oil-based materials refine processes and as adsorbents for environmental protection proposes. In this work MCM-41 and FeMCM41 were synthesized using rice husk ash - RHA as alternative to the conventional silica source. Hydrothermal synthesis was the method chosen to prepare the materials. Pre-defined synthesis parameters were 100°C for 168 hours, later the precursor was calcinated at 550°C for 2 hours under nitrogen and air flow. The sieves containing different proportions of iron were produced by two routes: introduction of iron salt direct synthesis; and a modification post synthesis consisting in iron salt 1 % and 5% impregnation in the material followed by thermal decomposition. The molecular sieves were characterized by X ray diffraction XRD, Fourier transform infrared spectroscopy FT-IR, X ray fluorescence spectroscopy XFR, scanning electronic microscopy SEM, specific surface area using the BET method, Termogravimetry TG. The kinetic model of Flynn Wall was used with the aim of determining the apparent activation energy of the surfactant remove (CTMABr) in the MCM- 41 porous. The analysis made possible the morphology characterization, identifying the presence of hexagonal structure typical for mesoporous materials, as well as observation of the MCM41 and iron of characteristic bands.