Mirele Costa da Silva

Membranas cerâmicas assimétricas tubulares: influência do tempo de deposição da camada filtrante na morfologia das membranas

Esse trabalho tem como objetivo obter membranas cerâmicas assimetricas para aplicacao em processos de microfiltracao e avaliar a influencia do tempo de deposicao (5 e 10 s) de uma dispersao de argila sobre um suporte tubular de alumina comercial e bentonita. O suporte tubular foi caracterizado por microscopia otica e eletronica de varredura e por porosimetria. A membrana assimetrica foi caracterizada por microscopia eletronica de varredura e por porosimetria. Os resultados mostraram suportes porosos com espessura de 1092µm, diâmetro medio de poro de 0,99  e porosidade de 39%. A membrana assimetrica foi obtida com sucesso para os tempos de deposicao avaliados, sendo classificada para aplicacoes em processos de microfiltracao atingindo diâmetro medio de poro de 0,25 µm e porosidade de 35%.

USE OF CERAMIC MEMBRANE FOR INDIGO SEPARATION IN EFFLUENT FROM TEXTILE INDUSTRY

The production of fabrics is one important sectors of the national economy, especially in jeans production. During dyeing step, in the production of jeans, it is generate a large amount of wastewater rich in indigo, a strong blue dye that when released directly into the environment is responsible for several environmental impacts. The aim of this work is to study the use of microfiltration ceramic membranes for indigo separation in effluents from textile industry. Initially the ceramic membranes were characterized in relation to the pore size and tangential flux. It was produced an indigo solution whose concentration and composition similar to the effluent of textile industry. The solution was characterized and submitted to a filtration through ceramic membranes by tangential flow, by applying a pressure of 3 Bar. At the end it was verified that 99% of the indigo was retained.

Effect of Sintering Temperature on Membranes Manufactured with Clays for Textile Effluent Treatment

The aim of this work is to use cheap raw materials, such as kaolin and ball clay, for the manufacture of ceramic membranes for application in effluent treatment from textile industry and to evaluate the influence of sintering temperature in the structural and morphological characteristics of those membranes. The ceramic mass was characterized by X-ray diffraction and thermal analysis. The membranes were characterized by scanning electron microscopy, Hg porosimetry, and water permeability with desalinated water. The variation in the sintering temperature directly affected the structural and morphological characteristics of the membranes. The increase in sintering temperature of the membranes has raised the average pores diameter from 0.116 to 0.179 µm but decreased the porosity of the membrane, from 40.30 to 25.16% for temperatures from 900 to 1100°C, respectively. The reduction in porosity of the membrane affected the water permeated flux and decrease from 35.82 Kg/h·m2 (at 1000°C) to 15.68 Kg/h·m2 (at 1100°C). All the membranes have been applied with success in the effluent treatment from textile industry, resulting in the decrease in turbidity and discoloration, reaching approximately 100% of rejection of solid particles.

Study of the Influence of Granite Residue in Different Compositions to Prepare Ceramic Membranes

The exploitation and processing of granite is responsible for generating large quantities of residue, mainly in the sawing step where is producing a dark color mud that is generally discharged directly in the environment without any treatment. The use of granite residue in the production of red ceramic has been widely studied and has shown promising results. The aim of this work is to verify the incorporation of granite residue in the preparation of tubular ceramic membrane in substitution of quartz. In this research it was done the characterization of the raw materials, the membrane preparation with different amount of granite residue and characterization of the membranes by scanning electron microscopy, mercury porosimetry and tangential flux measurements. The results showed that the changing in 10% of granite residue amount in the ceramic body was enough to change the morphological characteristics of the membranes.

Effect of Reaction Temperature in the Alumina Preparation by Combustion in a Muffle Furnace

The aim of this study is to evaluate the effect of temperature during the synthesis of alumina by combustion in a muffle furnace. The alumina was characterized by X-ray diffraction, particles size distribution and scanning electron microscopy. The results showed that the synthesis temperature of the alumina can affect the structure of the produced samples. The size distribution of the median particle diameter reached higher value for the alumina synthesized at 500°C with 16.07 μm, the range of the total distribution of particles is introduced to the large alumina synthesized 500 and 600°C and close synthesized when 700 and 800°C. The phase of the alumina was identified only after the synthesized sample at 800°C with crystallite size of 22.16 and 6.75 μm synthesized samples 800 and 900°C, respectively. With respect to morphology, increased synthesis temperature was not enough to significantly change.

Combustion Synthesis of ZnAl2O4 Catalyst Using Glycine as Fuel for the Esterification and Transesterification of Soybean Oil: Influence the Form of Heating

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.

Synthesis of Ni-Zn Ferrite Catalysts by Combustion Reaction Using Different Fuels

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.

Ceramic Membrane Made of Alumina Synthesized by Pechini Method for Application in Microfiltration Processes

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.

High Energy Milling of Alumina Synthesized by Combustion Reaction Using a Vertical Shaft Attritor Mill: Influence of the Milling Time Length

Among the vast applications in which the α-alumina can apply, the literature has reported researches which aim to achieve better features of these materials varying the obtainment methodology and some post-obtainment techniques. Thus, this paper aims to evaluate how different milling time lengths of 15, 30, 45 and 60 minutes alter the structure and morphology of α-alumina powders synthesized by combustion reaction. The time and temperature of the combustion reaction were evaluated during the synthesis of the alumina. The samples of non-milled and milled alumina were characterized by XRD and particle size analysis. The results showed that the maximum achieved temperature of reaction was 598°C. The milling time length variation did not alter the stable α-Al2O3 majority crystal phase present in all samples. The average particle diameter was reduced from 23.3 to 10.5 μm comparing the non-milled and the sample milled for 60s.

Effect of Calcination Temperature in the Aluminum Oxide Synthesized by Pechini Method in the Citric Acid: Metal Cation Ratio of 2:1

Through the constant search by researchers to obtain materials with improved properties, literature has presented an annual increase in the number of articles that seek to optimize in the methodology used to prepare nanopowders. In this way, the aim of this work is to study how the calcined temperature (500, 600, 700, 800, 900, 1000, 1100 and 1200oC) changes the final properties of the alumina synthesized by Pechini method with citric acid: metallic cation ratio of 2:1. The alumina was characterized by thermal analysis, X-ray diffraction, particle size analysis and scanning electron microscopy. The results showed a total of mass loss of 61.6%. The alumina phase appear at 800°C of temperature, however the α-alumina only appear at 1100oC. The increase in the calcined temperature increases the crystallite size and the crystallinity of the alumina and the great value reached for the agglomerates diameter was 13μm for the alumina calcined at 1200oC. In relation to the morphology of the alumina, it was observed heterogeneous particles with different size and irregular geometry, with aspect of high density.