Papers by Author: Normanda Lino de Freitas

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Authors: Mirele Costa da Silva, Francisco Nilson da Silva, Hélio de Lucena Lira, Normanda Lino de Freitas
Abstract: Given the diversity of areas in which applications of ceramic membranes are included, the literature has shown great interest of researchers to obtain these materials with powders synthesized by different chemical methods. Thus, this work aims at the synthesis of alumina by Pechini method, the 2:1 ratio of citric acid: metal cations, calcined to 1100°C, to obtain membranes. The synthesized powders were characterized by thermal analysis, XRD and particle size distribution, since the membranes were characterized by SEM and mercury porosimetry. The results for the obtained powders showed total mass loss of 61.60%, an alpha-alumina phase with crystallite size of 45.2 nm. As for the membranes, these showed heterogeneously distributed particles with different sizes and irregular geometry, reaching average pore diameter of 0.6 μm me 47% porosity, and thus are characterized for application in microfiltration processes.
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Authors: Juliana Pimentel Coutinho, Mirele Costa Silva, Simoni Margareti Plentz Meneghetti, Elvia Leal, Ana Cristina Figueiredo de Melo Costa, Normanda Lino de Freitas
Abstract: The aim of this work is to evaluate the esterification and transesterification activity of ZnAl2O4 catalysts obtained by different ways of heating during the combustion synthesis using glycine as fuel. Samples were prepared according to the propellants and explosives theory using a vitreous silica crucible as container, and as heating source, plate, muffle furnace and microwave oven. After synthesis, the samples were structural and morphologically characterized by: XRD, nitrogen adsorption and carbon content analysis, and employed in the esterification and transesterification reactions, the percentage of biodiesel formed (FAME) was determined by gas chromatography. The samples obtained on the plate, muffle furnace and microwave showed that even using different heating ways, led to the formation of ZnAl2O4 as majority phase, with crystallite sizes of 11, 15 and 10 nm, respectively. The samples present values of surface area ranging from 16 to 77 m2/g, particle size from 17 to 81 nm, and carbon content lower than 11%. The forms used for heating influenced the esterification and transesterification reactions, showing that there was a gap in the production of biodiesel, which is a promising indication that this material has potential to be used as catalysts on the biodiesel production.
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Authors: Normanda Lino de Freitas, Elias Fagury-Neto, Hélio Lucena Lira, Lucianna Gama, Ruth Herta Goldsmith Aliaga Kiminami, Ana Cristina Figueiredo de Melo Costa
Abstract: Among ceramic materials, the alumina has high importance because of its characteristics of resistance and refractory. The possibility to improve the final characteristics of this material, open possibilities for new applications. The aim of this work is to synthesize (α-Al2O3) alumina powders by combustion reaction and to evaluate the effect of the urea content in the final characteristics of the α-Al2O3 powders. Three compositions were studied : a) stoichiometric, b) with 10% of urea reduction and c) with 20% of urea reduction. The initial solution composition was based on the total valence of the reagents by using chemical concepts of the propellant. This powders were characterized by X-ray diffraction (XRD), granulometric determination by laser diffraction, nitrogen adsorption by BET, scanning electron microscopy (SEM), infrared spectroscopy (IR) and helium picnometer. The results showed that the urea reduction change the temperature of the reaction from 525 to 463oC , the characteristics of the powders, and principally the reduction of the particles size.
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Authors: Ester Pires de Almeida, Normanda Lino de Freitas, Ruth Herta Goldsmith Aliaga Kiminami, Hélio Lucena Lira, Ana Cristina Figueiredo de Melo Costa
Abstract: The aim of this study is to evaluate the thickness and permeability of the membranes of TiO2 supported on Al2O3. The TiO2 samples were prepared by combustion reaction method using monohydrated citric acid, aniline and urea as fuel. It was prepared three samples with different morphological characteristics. The membranes were prepared by dip coating, and characterized by scanning electron microscopy (SEM), permeate flux and turbidity in laboratory test. The membrane obtained with urea presented layer formed at 16 µm of thickness. For membrane obtained with powder from citric acid and aniline do not presented layer formation. The membrane obtained with samples synthesized urea showed: higher permeated flux (185.46 kg/ h.m ²), higher particle rejection (97%) and lower turbidity (0.99 NTU) with contaminated water. The membrane obtained with powders from citric acid and aniline showed: permeated flux of 128.61 and 138.41 kg/h.m², rejection of 96 and 95% and turbidity of 1.33 and 1.13 NTU, respectively.
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Authors: Kaline Melo de Souto Viana, Bruno Brito Dantas, N.A.S. Nogueira, J.M. Sasaki, Normanda Lino de Freitas, Ruth Herta Goldsmith Aliaga Kiminami, Ana Cristina Figueiredo de Melo Costa
Abstract: The aim of this work is to evaluate the influence of fuel in the synthesis of ZnAl2O4 catalytic supports by combustion reaction. For this, it was used the fuels: urea, carbohidrazide, glycine and aniline. The total amount of reagents was calculated according to the theory of propellants and explosive using urea in the stoichiometric proportion (Φe = 1). The structural and morphological characteristics of the powders were evaluated by XRD, FTIR, TEM, SEM and particle size distribution. The results from XRD showed the formation of the normal cubic spinel structure. The powders presented nanosized particles with narrow agglomerates size distribution. The powders prepared with urea showed better value of surface area and smaller crystallite size.
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Authors: V.V. Cordeiro, Normanda Lino de Freitas, Kaline Melo de Souto Viana, G. Dias, Ana Cristina Figueiredo de Melo Costa, Hélio Lucena Lira
Abstract: The aim of this work is to evaluate the influence of the external heating in the morphological and structural characteristics of the alumina powder prepared by combustion reaction. It was evaluated different types of external heating: muffle oven, microwave oven and ceramic plate with electrical spiral resistance. The powders were prepared according to the propellants and explosives theory, using urea in the stoichiometric proportion (Φe = 1). During the synthesis parameters such as flame combustion time and temperature were measured. The structural and morphological characteristics of the powders were evaluate by XRD, particle size distribution, SEM and nitrogen adsorption (BET). The results showed the production of -alumina as unique phase and formed by agglomerates with irregular plate shape of thin particles for all studied conditions. The powders prepared by electrical oven presented small particle size, with narrow agglomerates size distribution.
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Authors: M.A.F. Ramalho, Normanda Lino de Freitas, Ana Cristina Figueiredo de Melo Costa, Hélio Lucena Lira, Heloysa Martins Carvalho Andrade, Lucianna Gama
Abstract: The addition of zirconia to alumina can improve the chemical properties, mechanical stability, acidity and surface area of alumina. The aim of this work is to evaluate the influence of 0.005 moles of zirconia addition to the structure and morphology of alumina powders by combustion reaction. The compositions were called AP (alpha-Al2O3) and AZ (Zr0.005Al1.995O3) and were prepared by using a silica container with direct heating on a hot plate at 480oC until selfignition. The powders were characterized by X-ray diffraction and nitrogen adsorption by BET analysis. The composition AZ showed high surface area (47 m2/g) and small crystallite size (60 nm). The alpha-alumina AP showed a wide agglomerates distribution with small agglomerates size when compared with AZ composition.
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Authors: Laédna Souto Neiva, Lucianna Gama, Normanda Lino de Freitas, Heloysa Martins Carvalho Andrade, Artur Jose S. Mascarenhas, Ana Cristina Figueiredo de Melo Costa
Abstract: This work has as objective the synthesis for the method by combustion reaction of catalytic supports of α-Al2O3 modified with ZnO and Fe2O3 with and without impregnation of the species it activates (Ni) and your structural and morphologic characterization. The catalytic supports were obtained by method of the synthesis da combustion reaction. The catalytic supports were characterized by XRD, adsorption of nitrogen by BET method and infrared. The results of XRD showed the formation of powders with high cristalinity, characteristic picks of difraction of the phase α-Al2O3 indicating that there was the partial substitution of the ions of Al3+ for Zn2+ and Fe3+ in the hexagonal net of the alumina. The impregnation of the nickel promoted an increasing in the size of the particles, this carried to reduction of the superficial area of the same, of the volume and of the diameter of the pores of the structure of the material. Were accomplished catalytics tests in row of seats scale. The result of catalytic tests showed that the developed catalysts in this work were efficient in the methane conversion process.
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Authors: Valéria Vital Cordeiro, Mirele Costa da Silva, Hélio Lucena Lira, Normanda Lino de Freitas, Ana Cristina Figueiredo de Melo Costa
Abstract: Through different field of application and productive growth that membrane technology has been presented in the last years, the aim of this work is to prepare and characterize anisotropic porous ceramic membrane. The membrane were done with alumina, prepared by combustion reaction in microwave oven from urea as combustible and after deposited on support based on a commercial alumina. The results showed that it was obtained α-alumina as unique phase with average agglomerate size of 10µ and surface area of 33 m2/g. The alumina morphology was constituted by pre-sintering particles with hard agglomerates and/or aggregates. In relation to the membranes, it was observed a longitudinal section without cracks and uncovers support surface, also it can be observed grain formation well distributed and a layer of alumina with approximately 35.25µm. In relation to the permeate flux, the membrane presented initially values relatively high that is decrease with the permeation time, due to adsorption of water in the internal surface of the pores of the membrane, experiencing a decrease in size.
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Authors: Normanda Lino de Freitas, Juliana Pimentel Coutinho, Mirele Costa Silva, Hélio Lucena Lira, Ruth Herta Goldsmith Aliaga Kiminami, Ana Cristina Figueiredo de Melo Costa
Abstract: The aim of this work is to evaluate the effect of different fuels in the preparation of Ni-Zn ferrites by combustion reaction. The catalysts were prepared according to the propellants chemistry, in stoichiometric composition, using a vitreous silica container. Carbohydrazine, monohydrated citric acid and glycine fuels were used. During the synthesis parameters as flame combustion time and temperature were measured. The structural and morphological characteristics of the powders were evaluated by XRD, textural analysis by nitrogen adsorption and SEM. The fuel monohydrated citric acid presented the greatest time and temperature of combustion reaction. The results show that the type of fuel changed the final characteristics of the powders. The XRD results showed the formation of Ni-Zn ferrite phase for all fuels used in this study. The powders prepared with carbohydrazine resulted in largest value of surface area. All powders showed morphology constituted by soft agglomerates of nanoparticles.
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