Materials Science Forum Vols. 660-661

Abstract: The petroleum industry generates huge amounts of oily sludge during the process of oil and gas extraction. This waste is a pollutant material that can cause environmental damage. Because of this, it has been treated with bentonite clay, being referred as encapsulated petroleum waste. In this work the chemical-environmental characterization and classification of the petroleum waste were done according to ABNT standards. The results indicated that the encapsulated petroleum waste should be classified as Class IIA – “No Inert”. Therefore, it could be used in manufacture of ceramic products for civil construction.

Abstract: The general aim of this study was to develop materials of the type: Y zeolite (hydrothermal synthesis), ceramic support (forming of powder) and zeolite membrane (rubbing). The preparation of the Y zeolite was conducted in accordance with the hydrothermal synthesis method, the time of crystallization was one day. The ceramic support was prepared by means of the forming of powder technique and subsequently subjected to sintering at a temperature of 1400°C/1h. The zeolite membrane (Y/α-alumina) was prepared by secondary growth method (rubbing). These materials were characterized by XRD and SEM. Obtaining Y zeolite could be confirmed by X ray diffractograms. From the images obtained by SEM, it was possible to derive from analysis that the Y zeolite is composed of a homogeneous morphology, where the particles are crowded, with uniform size. The results obtained for the ceramic support (α-alumina) showed that it displays characteristics peaks of aluminum oxide. By using micrographs it was possible to observe a heterogeneous microstructure with a compact form, without cracks upon the layers. According to the XRD, for the methodof secondary growth (rubbing), it was observed that the Y zeolite wich had been synthesized on the ceramic support displayed a crystalline structure. The micrography of the zeolite membrane (Y/α-alumina) showed the formation of a layer of zeolite on the ceramic support.

Abstract: The performance of the alkaline processes on the properties of cation exchange capacity (CEC) and swelling was studied in three different types of bentonite from Brazil, Argentina and Mozambique. Alkaline activations were performed by means of mechanochemical reactions with solutions of NaOH and Na2CO3, to increase the sodium content of bentonite clays and, thus, improve the properties above. Clay samples were characterized by X-ray diffraction, to obtain the constituent phases. Activated samples were evaluated according to their cation exchange capacity – determined by the methylene blue test, and swelling index – measured by the Foster’s method. Results showed that the activation improved the properties of all bentonite types, especially the Brazilian clay, which achieved the most significant raises. There was also an indication that the type of clay affect the processing.

Abstract: The search for new sources of renewable energy order to minimize environmental impacts has led the scientists to develop new alternatives, such as the use of recycling of frying oils to produce biodiesel. The utilization of fuels of agricultural origin in the cycle diesel engines is a good alternative to reduce dependence on importation petroleum, since these fuels are a renewable source of energy. The utilization of biodiesel as biofuel is a contribution to the environment, reducing the qualitative and quantitative form levels of environmental pollution. However, these oils should go through a process of decontamination and decoloration up the stage of chemical conversion which is used clay to lighten the oil. This study aimed to characterize clay of Paraíba to be used in the clearing of frying oil. It was observed through the technique of kinematic viscosity the clays show good results in treatment used vegetable oils.

Abstract: The purpose of this study was to investigate the porosity behavior of dust cakes formed by phosphatic concentrate along filtration time. Filtration trials were performed for four different pressure drops. The fabric filter used as filter medium was a polyester felt. The dust cakes obtained were submitted to a hardening process and their images were acquired with the use of a SEM. The images generated by the SEM were analyzed by using an image analyzing program that supplied the cake porosity values. Porosity values were also estimated using Ergun’s modified equation. Results show that porosity presents higher values when calculated using the image analyzing program, but has the same behavior as the results found with Ergun’s equation. It was also observed that porosity is not constant during filtration; therefore it can be concluded that the dust cake is compressible.

Abstract: The addition of a fourth component in the system composed by polymer/ solvent/ non-solvent is a technique generally employed to enhance membrane properties. Since polysulfone presents low hydrophilicity, which can hamper filtration performance, the addition of a hydrophilic material can be an important technique to improve this property. Therefore, the main purpose of this work is to understand the influence of addition of the activated carbon in the system polysulfone/ NMP/ water in terms of membrane morphology, hydrophilicity, thermal and mechanical resistance. From scanning electron micrographs, it could be seen that membrane surface became denser with the addition of higher activated carbon contents and the cross-section morphology was not changed. Acid-base interactions were favored with the activated carbon addition and the availability of Lifshtiz-van Der Waals interactions was decreased, being these two properties very important to avoid fouling formation onto membrane surface. The glass transition temperatures of the polysulfone composite membranes with higher activated carbon contents were increased. However, all activated carbon contents brittled the composite membranes in relation to the pristine polysulfone membrane.

Abstract: The present study is about the effect of oxide layers in creep of Ti-6Al-4V alloy, in different atmospheres (air, nitrogen and argon). Ti-6Al-4V alloy was treated during 24 hours in a thermal treatment furnace at 600°C in different atmospheres (argon, nitrogen and air). The samples were analyzed by High Resolution X-Ray Diffraction, Scanning Electronic Microscopy (SEM), Atomic Force Microscopy (AFM) and microhardness test. The polished samples of Ti-6Al-4V allloy were treated during 24 hours at 600°C and the oxidation behavior in each case using argon, nitrogen and air atmospheres was observed. The oxidation was more aggressive in air atmosphere, forming TiO2 film in the surface. The oxidation produced a weight gain through the oxide layer growth and hardening by oxygen dissolution. Ti-6Al-4V alloy specimens also were produced in order to test them in creep, at 250 MPa and 600°C, with argon, nitrogen and air atmospheres. When the Ti-6Al-4V alloy was tested under argon and nitrogen atmospheres oxidation effects are smaller and the behavior of the creep curves shows that the creep life time was better in atmospheres not so oxidant. It is observed a decreasing of steady state creep in function of the oxidation process reduction. It is shown that, for the Ti-6Al-4V alloy, their useful life is strongly affected by the atmosphere that is submitted, on account of the oxidation suffered by the material.

Abstract: Smectites are clay mineral with a layered structure and nanometric thickness, high specific area and a huge variety of uses. Consisting on stacked layers of about 1nm thickness, including two silica tetrahedral and one octahedral sheet. Properties of natural Smectites can be enhanced by organic modification, due to the substitution of the exchangeable cations in the interlayer area. In fact, the properties of the modified smectite (organophilic clay) are related to its modified chemical composition and structural parameters. The interaction of smectite clays with surfactants has an important interest in the fields of drilling fluids, paints, cosmetic, ceramic industries and others. Recent applications are: remediation of contaminated areas and polymer/clay nanocomposites. The aim of this paper is to obtain organophilic clays using a bentonite from the Chiqui Gómez deposit in Central Cuba. The raw and organophilic clays were analyzed by DRX, SEM, swelling capacity in organic solvents and others.

Abstract: In this work the hydrodynamics behaviour of a horizontal vibrofluidized bed (VFB) is analyzed through pressure drop versus air velocity and standard deviations of pressure drop versus air velocity curves with different vibration conditions. The influence of parameters such as frequency and vibration amplitude, as well as bed material loaded, were evaluated and quantified through statistical analysis. A strong linear mass influence was observed on the bed pressure drop for all amplitude levels. For the amplitude it was observed a quadratic function related to pressure. The lowest level of vibration frequency there were the higher velocity values, and they were more accentuated for the intermediate amplitude levels. We found higher values for the minimum vibrofluidization velocity for the same condition of higher mass and intermediate values of amplitude.

Abstract: The development of big cities and industrialization has been causing environmental degradation problems, damaging natural and energetic resources, besides the bigger production of wastes. So, it is essential the use of renewable alternative fuels, and industrial wastes processing. Biomass can be used in direct combustion, thermo chemical and biological processes. The fume powder is an important waste of tobacco industries. This work makes a characterization of fume powder, originated from Souza Cruz (Uberlândia unit); the objective is to realize the fast pyrolysis in a bubble fluidized bed. Physical analyses of the powder were made to determine the size distribution, and the medium diameter; the solids density and moisture content (dry base). The elementary composition of the material was also determined. The powder fluidization in an acrylic bed (160 cm heights, 10 cm id), was realized to obtain the minimum fluidization velocity.