Navegando por Assunto "Infrared"
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Item Acesso aberto (Open Access) Diferenciação catiônica de bentonitas por infravermelho: um estudo dos efeitos da hidratação dos cátions trocáveis(Universidade Federal do Pará, 2020-04-13) RODRIGUES, Andréia Oliveira; PAZ, Simone Patrícia Aranha da; http://lattes.cnpq.br/5376678084716817; https://orcid.org/0000-0002-5880-7638In the bentonite industry, the most common procedure for quality control of the ore and the sodium activation process is the swelling method. However, this tool is restricted only to the differentiation of the sodium and non-sodium types, not considering the other cationic varieties. The analysis of the composition of exchangeable cations requires laborious procedures, with daily cationic exchanges (between 3 and 6 days) and chemical analysis Via Humid, which would be unfeasible for this type of industry. Despite this, knowledge of the cationic type is of paramount importance, as it would help in the implementation of a technological route of better quality and efficiency of sodium activation. In this context, he sought in this work to establish cationic differentiation parameters for bentonites based on near and medium infrared spectroscopy for the investigation of hydration of exchangeable cations. Particle size distribution (DTP) and N2 BET adsorption-desorption isotherms were also used. Eleven smectites were studied, including one Mg-montmorillonite and two from the Clay Minerals Society repository: SWy-2 (Na-montmorillonite) and SAz-1 (Ca-montmorillonite). The clay fraction obtained by granulometric separation was characterized by FRX, DRX, CTC and PCZ. Previous heat treatment by drying at 105 ºC for 24 h and dehydration at 400 ºC for 2 h. Exchangeable cations and hydration influenced the absorption bands of water molecules in the near and medium spectral region, showing that they are strongly influenced by the size and charge of the ions (monovalent and divalent). The cationic differentiation was observed by the intensity of these bands. Absorptions close to 3620 cm-1 were attributed to water directly linked to cations, however, differentiation was only possible in samples dried at 105 ºC, because at this temperature they still remain hydrated. The reduction in the intensity of this band is due to the decrease in the water content, due to dehydration of the interlayer after heating to 400 ºC, which does not favor differentiation. The absorptions close to 3430 cm-1 were attributed to the adsorbed water molecules, as well as the complex band in 7072 cm-1, obtaining a spectrum, in descending order, Ca, Mg and Na. DRIFT spectroscopy in the nearby region was considered a simple, fast and low-cost analysis technique that allowed to distinguish different types of bentonites.Item Acesso aberto (Open Access) Técnicas para avaliação do desempenho térmico e lumínico associado a sistemas de prateleira de luz em clima quente e úmido(Universidade Federal do Pará, 2013-09-27) SILVA, Marcelle Vilar da; FRANCO, Irving Montanar; http://lattes.cnpq.br/4254203203850909When using a daylight system in a hot and humid climate region, with a elevated number of hours of insolation and high intensity of solar radiation, it is mandatory to evaluated the effects on the thermal performance and environmental luminosity, to identify their potential for use in a controlled and appropriate manner. The aim is to carry out a performance analysis, but more specifically ensure a critic and carefull approach to methodology for assessing the increase of heat, light gains -in hot and humid climate-, through fenestrations with shading protection systems, the comparative studies of efficiency where done to compared systems with and without shading protection through the calculation of solar heat gains using the CSTB method (adapted by Frota e Schiffer), internal illuminance levels where done with computer simulations (RELUX 2006), variation of internal temperatures (ECOTEC v.2) and measurements under real sky condition, with reduced scale models, air temperature measurement, globe temperature and internal and external illuminance, using data loggers, for calculating the daylight coefficient (CLD), infrared thermal imaging to monitor the internal and external surface temperatures. Processing data with auxiliary of regression curves where used to ensure the accuracy of the measurements and identify the quality of the equipment and data refinement. Where verified as results that the systems had very similar performance, but with some relative indicative differences levels for internal illuminance. The shading method analyses shown similar analytical angle generated by the solar protections adopted the prototypes, offering a 40.14% reduction on the thermal load for the north façade. The simulations indicate that the proposed lightshelf could reveal potencial for luminance levels improvements at the center portion of the environment when compared to the tradicional shading device, indicative of potential for future studies. The internal temperature measurements generated very close values between the shelf and the traditional light shading device, what was not enough to demonstrate differential heating. Studies in infrared shown to be efficient to identify surfaces temperatures conditions as thermal energy – heat gains -, drived inside by the boards of the shading device and the lightshelf. For the light shelf the internal illuminance measurements showed significantly increased levels near the window, and at the more inner illuminance measurement point presented an difference of 500lux , this specifically occurred regarding the traditional shading device only 11:00 to 13:30. The DLF – Day Light Factor - indicated that the availability of light in the environment of the center position of the prototype is higher with light shelf than with the traditional shading device and in the more inner illuminance measurement point both indicate mostly similar performances.