Navegando por Autor "DIAZ, Francisco Rolando Valenzuela"

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Síntese de zeólita do tipo faujasita a partir de um rejeito de caulim
(2012-12) HILDEBRANDO, Edemarino Araujo; ANGÉLICA, Rômulo Simões; NEVES, Roberto de Freitas; DIAZ, Francisco Rolando Valenzuela
Zeolitic materials were synthesized using as main source of silicon and aluminum an industrial waste generated during the processing of kaolin for paper coating, the starting material and formed phases as reaction products were characterized by XRD, SEM and DRIFT. The synthesis process occurred in hydrothermal conditions and the effects, time-temperature, as well as the relations Si/Al and Na/Al were considered. The results show that in the methodology developed from kaolin waste, initially calcined at 700 ºC for 2 h, subjected then reaction in alkaline medium at 90 ºC for 48 h in presence of additional silica was obtained faujasite-type zeolite with good crystallinity as phase predominant in the synthesis product.
Acesso aberto (Open Access)
Síntese e caracterização de argila esmectita Zn-estevensita
(2014-06) HILDEBRANDO, Edemarino Araujo; VALENZUELA, Maria das Graças da Silva; NEVES, Roberto de Freitas; DIAZ, Francisco Rolando Valenzuela
Clay of the smectite group was successfully obtained at a low temperature hydrothermal processing using sodium metasilicate, zinc nitrate and urea as precursor materials. During the synthesis step, the molar composition of the mixture and the temperature remained constant varying the reaction time. The synthesized samples were characterized by X-ray diffraction, scanning electron microscopy, diffuse reflectance Fourier Transform infrared spectroscopy, differential thermal analysis and thermogravimetry, cation exchange capacity (CEC) and BET surface area measurements. The results show that in the methodology utilized is obtained Zn-stevensite with specific surface area of 171.6-203.4 m2/g and good crystallinity as present single phase in the reaction product after static synthesis at 90 ºC for 44 to 138 h, indicating that, the increased synthesis time is an important parameter for crystallization process of the clay.
Acesso aberto (Open Access)
Synthesis and characterization of zeolite NaP using kaolin waste as a source of silicon and aluminum
(2014-08) HILDEBRANDO, Edemarino Araujo; ANDRADE, Christiano Gianesi Bastos; ROCHA JUNIOR, Carlos Augusto Ferreira da; ANGÉLICA, Rômulo Simões; DIAZ, Francisco Rolando Valenzuela
The synthesis of zeolite NaP using kaolin waste, from the Amazon region, as a predominant source of silicon and aluminum has been studied. The zeolitisation process occurred in hydrothermal conditions using static autoclaving and the effects of time, temperature, and the Si/Al ratio were investigated. The starting material and the phases formed as reaction products were characterized by XRD, SEM and FTIR. The results showed that pure zeolite NaP is hydrothermally synthesized, at 100 °C for 20 hours, using metakaolin waste material in alkaline medium in presence of additional silica. The XRD and SEM analyses indicate that the synthesized zeolite presents good crystallinity.