Crystalline Silica
Mostrando 13-24 de 55 artigos, teses e dissertações.
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13. Properties of silica from rice husk and rice husk ash and their utilization for zeolite y synthesis
This study compared properties of silica (SiO2) from rice husk (RH) and rice husk ash (RHA) extracted by acid- and heat-treatment. The SiO2 from RH was in amorphous phase with nearly 100% purity while that from RHA was in crystalline phase with 97.56% purity. Both extracted SiO2 were used in the synthesis of zeolite NaY but that from RH was better due to the
Química Nova. Publicado em: 2011
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14. Osmotic stress on concentrated colloidal suspensions: a path towards equilibrium?
We discuss in this study the advantages and limitations of the osmotic stress method that enables to set the osmotic pressure to a given system. By investigating aqueous suspension of monodisperse silica nanoparticles of radius 78 at an ionic strength of 10-2 mol/L, we show that the method is very accurate to probe the phase behavior of colloidal suspensions
Brazilian Journal of Physics. Publicado em: 2009-04
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15. Materials hierarchically structuralized with mesoporosa cubical phase: synthesis, characterization and use as support in the immobilization of enzyme HRP / Materiais hierarquicamente estruturados com fase cúbica mesoporosa: síntese, caracterização e uso como suporte na imobilização da enzima HRP
Hierarchical silica porous materials have been successfully synthesized using polystyrene nanospheres as macropore template, triblock copolymer Pluronic F127 as mesopore template, tetramethyl orthosilicate as silica source and ethanol as cosurfactant. The obtained materials were characterized by XRD, TG-DTA, N2 adsorption, Hg porosimetry, SEM, HRSEM, TEM and
Publicado em: 2009
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16. Synthesis and characterization of hematite pigment, obtained from a waste steel industry / Síntese e caracterização de pigmento de hematita, obtido a partir de um subproduto da indústria siderúrgica
In the ceramic industry of wall and floor tiles, whose selection is strongly influenced by the visual aspect of the decorated surface, the color becomes one of the most important characteristics. With the purpose to search for new pigments that replace or optimize the already known, news method to synthesis are being researched, such as new pigments system a
Publicado em: 2009
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17. Vocal symptoms in workers of an alcohol and sugar mill / Sintomas vocais em trabalhadores de uma usina de álcool e açúcar
Aim: To investigate the vocal symptoms reported by workers of an alcohol and sugar mill exposed to noise and/or chemical substances. Justification: The vocal demand, physical and chemical agents may be considered risk factors for vocal disorders. Continuous exposure to noise and the presence of some pollutants (dust, smoke and others) may potentially lead to
Publicado em: 2009
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18. Formação de mesoporos na síntese de zeólitas ZSM-5 via nanomoldagem avaliação no craqueamento de n-decano / Formação de mesoporos na síntese de zeólitas ZSM-5 via nanomoldagem avaliação no craqueamento de n-decano
The use of zeolites in the cracking of hydrocarbons is limited because the molecules higher than 0.74 nm do not diffuse in their micropores. In the other hand, molecular sieves as MCM-41, MCM-48 ou SBA-15, whose diameters are up 10 nm for the two formers and up to 30 nm for the last, have low hydrothermal stability and catalytic activity. To overcome those l
Publicado em: 2008
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19. APLICAÇÃO DE PROCESSOS OXIDATIVOS AVANÇADOS HOMOGÊNEOS E HETEROGÊNEOS NA DEGRADAÇÃO DE EFLUENTES DE CURTUME
This study investigated the application of advanced oxidative processes for the homogeneous and heterogeneous degradation of a tanning effluent. The catalytic activity of a solid oxide containing manganese was evaluated in the heterogeneous systems. The experiments were performed in a photocatalytic batch reactor in laboratory scale. The solid used was the c
Publicado em: 2008
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20. Caracteristicas da poeira do processo de fabricação de materiais ceramicos para revestimento : estudo no polo de Santa Gertrudes / Characteristics of dust from the manufacturing process of ceramic materials for tiles : study in the Santa Gertrudes complex
Dust generated in the process of manufacturing ceramic materials may be a hazardous agent to the health of workers, especially when silica polymorphs in crystal forms of ?-quartz and cristobalite are present in its composition. Occupational exposure to respirable dust of such polymorphs may lead to the onset of lung disease named silicosis and other associat
Publicado em: 2007
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21. Termodecomposição, estudos de carbonização e silicificação da matéria orgânica e corpos silicosos em ecossistemas terrestres no Brasil e na Antártica / Thermodecomposition, organic matter carbonization silicification studies and silica bodies in terrestrial ecosystems in Brazil and Antarctica
Soil organic matter (SOM) is highly heterogeneous in composition, which consists of components as different from each other as labile carbohydrates and recalcitrant aliphatic compounds. Mean residence time (MRT) of the various compounds comprising soil organic matter may range from a few minutes to thousands of years. This wide range is partly due to the soi
Publicado em: 2007
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22. A utilização da cinza da casca de arroz de termoelétrica como componente do aglomerante de compósitos à base de cimento Portland / The use of thermoeletrical rice husk ash as component of mixtures based in cement agglomerate
Industrial residues, such as pozzolan, can be incorporated in concretes as a solution for polluter refuses, according to sustainable principles. The objective of this work it is to discuss and analyze the use of rice thermoeletrical industry residue, the rice rusk ash (RHA), as mineral addition in durable concretes. The RHA can be used to increase the compre
Publicado em: 2007
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23. As rochas alcalinas de Cananéia, litoral sul do Estado de São Paulo: estudos mineralógicos, geoquímicos e isotópicos / Alkaline rocks of Cananéia, south coast of the state of São Paulo: mineralogy, geochemistcal and isotopical studies
The alkaline occurrence of Cananéia, SE Brazil, lying in the southern part of the homonymous island, is a subcircular intrusion 1.8 km² in area (Morro de São João) and 137 m high. A small and petrographically similar satellite body (Morrete) is found in the adjacent Ilha Comprida. Geomorphologically, it belongs to the Cananéia-Iguape Coast Plain. It is
Publicado em: 2007
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24. Obtenção de fritas vitrocerâmicas a partir de resíduos sólidos industriais / Glassceramics frits attainment from industrial solid wastes
This work studies the residue obtained from the process of aluminum metal extraction activities, a great interest process, because of Brazil own some of the biggest bauxite mineral reserves in all the world. As a useful choice for no residue generation, and a support for environmentally friendly technologies, this work studies the white dross residue (WDR),
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 15/09/2006