Síntese e caracterização de compostos de coordenação do Ácido 4-cloro-2-(2- furilmetilamino)-5- sulfamoil-benzóico com os íons níquel, cobalto e zinco

This work aimed to promote the synthesis, characterization and propose a plausible molecular structure for coordination compounds involving furosemide (4-Chloro-2-(2- furylmethylamino)-5-sulfamoyl-benzoic acid) with the metal ions Ni+2, Zn+2 and Co+2. The compounds were obtained in methanoic medium by evaporation of the solvent after the synthesis procedure. For characterization of coordination compounds determining the levels of metals by EDTA complexometry, infrared spectroscopy (FTIR), solubility of compounds in various solvents, thermogravimetry (TG), differential scanning calorimetry (DSC), differential thermal analysis were made (DTA), determination of the carbon , hydrogen and nitrogen (CHN). The results of infrared spectroscopy in the region suggest that the organic ligand is coordinated in a bidentate fashion to the metal ions, the metal center interactions to occur by the coordination of the nitrogen atom of the amino group and the oxygen atom of the carboxylic acid of the structure of furosemide. With the results of the levels of metal, elemental analysis (CHN) and thermal analysis has been possible to propose the structure of the ligand. The values of the molar conductivity of the complex in acetonitrile behavior suggest the non acetonitrile electrolyte solution. With the solubility tests it was found that the compounds have high solubility in methanol and acetonitrile, as are partially insoluble in water. From the results of thermal analysis (TG, DSC, DTA), it was possible to obtain the thermal behavior of the compounds as stages of dehydration, thermal stability, decomposition and the energies involved.

Síntese de ferritas de cobalto e níquel dopadas com zinco e caracterização de suas propriedades eletromagnéticas

This work shows that the synthesis by combustion is a prominent alternative to obtain ceramic powders of higher oxides, nanostructured and of high purity, as the ferrites of formulas Co(1-x)Zn(x)Fe2O4 e Ni(1-x)Zn(x)Fe2O4 with x ranging from 0.2 mols, in a range from 0.2 ≤ x ≥ 1.0 mol, that presents magnetic properties in coexistence of ferroelectric and ferrimagnetic states, which can be used in antennas of micro tapes and selective surfaces of low frequency in a range of miniaturized microwaves, without performance loss. The obtainment occurred through the combustion process, followed by appropriate physical processes and ordered to the utilization of the substrate sinterization process, it gave us a ceramic material, of high purity degree in a nanometric scale. The Vibrating Sample Magnetometer (VSM) analysis showed that those ferritic materials presents parameters, as materials hysteresis, that have own behavior of magnetic materials of good quality, in which the magnetization states can be suddenly changed with a relatively small variation of the field intensity, having large applications on the electronics field. The X-ray Diffraction (XRD) analysis of the ceramic powders synthesized at 900 °C, characterize its structural and geometrical properties, the crystallite size and the interplanar spacing. Other analysis were developed, as Scanning Electron Microscopy (SEM), X-ray Fluorescence (XRF), electric permittivity and the tangent loss, in high frequencies, through the equipment ZVB - 14 Vector Network Analyzer 10 MHz-14 GHz, of ROHDE & SCHWART.

Síntese e caracterizações estrutural e magnética das ferritas de cobalto-manganês (Co1-xMnxFe2O4 E Co1,2Fe1,8-xMnxO4)

The cobalt-manganese ferrites (Co1¡xMnxFe2O4 and Co1,2Fe1,8¡xMnxO4) has a mixed structure of spinel type and it has been regarded as one of candidates for petitive wide variety of applications in devices from ultrasonic generation and detection, sensors, transformers, as well as in medical industry. Ferrites cobalt-manganese nanostructured were produced via mechanical alloying with subsequent heat treatment and were characterized by X-ray diffraction, X-ray fluorescence, scanning electron microscopy and magnetization. Samples of Co1¡xMnxFe2O4 and Co1,2Fe1,8¡xMnxO4 were obtained from the precursor powders Fe3O4, Co3O4 and Mn3O4 which were stoichiometrically mixed and ground by 10h and heat treated at 900°C for 2h. The diffraction confirmed the formation of the pure nanocrystalline phases to series Co1,2Fe1,8¡xMnxO4 with an average diameter of about 94nm. It was found that the lattice parameter increases with the substitution of Fe3Å by Mn3Å. The x-ray fluorescence revealed that the portions of metals in samples were close to the nominal stoichiometric compositions. The microstructural features observed in micrographs showed that the particles formed show very different morphology and particle size. The magnetic hysteresis measurements performed at low temperature showed that the saturation magnetization and remanence increased as the concentration of manganese, while the coercive field decreased. The anisotropy constant (Ke f ), was estimated from the data adjustments the law of approaching saturation. It was found that the anisotropy decreases substantially with the substitution of Fe by Mn.

Investigação da rota biohidrometalúrgica com Acidithiobacillus ferrooxidans/thiooxidans para recuperação do cobalto de baterias de íons lítio descartadas

The recycling of metals from secondary sources can be advantageous. Among the metals of interest, we have cobalt, a metal used for various purposes. As regards the secondary sources of cobalt, the lithium-ion batteries can be considered, since they contain cobalt oxide in their composition (LiCoO2). This way, the objective of this work was to use the microorganism strains (Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans) to bioleach the LiCoO2 extracted from discarded lithium ion batteries with emphasis on the recovery of cobalt for synthesis of new materials of interest. The lineage growth occurred in T&K medium and the growth investigation was made by observing the media, by platelet growth and microscope analysis. Then, the inoculum was standardized on 5 x 106 cells mL-1 and used in bioleaching tests. The bioleaching was investigated: the microorganism nature: separate strains and A. ferrooxidans and A. thiooxidans consortium, bioleaching time (0 to 40 days), inoculum proportion (5 to 50% v/v), energy source (iron and sulfur) and residue concentration (1063 to 8500 mg L-1 of cobalt). The cobalt concentration in the media was found by atomic absorption spectrometry and the medium pH was monitored during the bioleaching. The results show that the amount of bioleached cobalt increases with time and the iron concentration. The bioleaching with A. thiooxidans was not influenced by the addition of sulfur. The use of the two lineages together did not improve the bioleaching rates. Among the lineages, the A. thiooxidans presented better results and was able to bioleach cobalt amounts above 50% in most of the experiments. A. thiooxidans presented lower bioleaching rates, with a maximum of 50% after 24 days of experiment. After reprocessing by bioleaching, the cobalt in solution was used for synthesis of new materials: such as LiCoO2 cathode and as adsorbent pesticide double lamellar hydroxide (HDL Co-Al-Cl) by the Pechini and co-precipitation methods. The reprocessed LiCoO2 presented a unique stoichiometric phase relative to the HT-LiCoO2 structure similar to the JCPDS 44-0145, presenting electrochemical activity when tested as a cathode material. The double lamellar hydroxide Co-Al-Cl was tested as pesticide adsorbent, being possible to adsorb around 100% of the pesticide. The bioleaching was efficient in the recovery of cobalt present in lithium-ion batteries and microorganisms presented high tolerance to the residue, being able to bioleach even at higher LiCoO2 concentrations. The cobalt bioleaching medium did not impair the synthesis phases and the obtained materials presented structure and activity similar to the sintered materials from the reagents containing cobalt.

Aplicação das fórmulas CIELAB e CIEDE2000 na avaliação da cor de folhas vegetais irradiadas por uma fonte de Cobalto-60

A cor dos alimentos está directamente associada à sua aceitação pelo consumidor. A procura de métodos de processamento seguros e eficazes destaca a radiação ionizante, já que permite a desinfecção do alimento e a extensão do seu tempo de prateleira [1]. O espaço de cor CIELAB é comummente utilizado para avaliar diferenças de cor (ΔE*) entre dois objectos. No entanto, a fórmula CIEDE2000 permite atenuar variações entre valores calculados e percepcionados [2]. O impacto da radiação ionizante na cor de um vegetal folhoso foi avaliado durante o tempo de armazenamento e os resultados discutidos utilizando ambas as fórmulas de ΔE*.

Obtenção de óxidos a base de níquel e cobalto para reação de oxidação parcial do metano

Nickel-based catalysts supported on alumina have been widely used in various reactions to obtain synthesis gas or hydrogen. Usually, higher conversion levels are obtained by these catalysts, however, the deactivation by coke formation and sintering of metal particles are still problems to be solved. Several approaches have been employed in order to minimize these problems, among which stands out in recent years the use of additives such as oxides of alkali metals and rare earths. Similarly, the use of methodologies for the synthesis faster, easier, applicable on an industrial scale and to allow control of the microstructural characteristics of these catalysts, can together provide the solution to this problem. In this work, oxides with spinel type structure AB2O4, where A represents divalent cation and B represents trivalent cations are an important class of ceramic materials investigated worldwide in different fields of applications. The nickel cobaltite (NiCo2O4) was oxides of spinel type which has attracted considerable interest due to its applicability in several areas, such as chemical sensors, flat panel displays, optical limiters, electrode materials, pigments, electrocatalysis, electronic ceramics, among others. The catalyst precursor NiCo2O4 was prepared by a new chemical synthesis route using gelatine as directing agent. The polymer resin obtained was calcined at 350°C. The samples were calcined at different temperatures (550, 750 and 950°C) and characterized by X ray diffraction, measurements of specific surface area, temperature programmed reduction and scanning electron microscopy. The materials heat treated at 550 and 750°C were tested in the partial oxidation of methane. The set of techniques revealed, for solid preparations, the presence of the phase of spinel-type structure with the NiCo2O4 NixCo1-xO solid solution. This solid solution was identified by Rietveld refinement at all temperatures of heat treatment. The catalyst precursors calcined at 550 and 750°C showed conversion levels around 25 and 75%, respectively. The reason H2/CO was around 2 to the precursor treated at 750°C, proposed reason for the reaction of partial oxidation of methane, one can conclude that this material can be shown to produce synthesis gas suitable for use in the synthesis Fischer-Tropsch process

Síntese e caracterização de óxidos de cério e cobalto obtidos por gel-combustão e Pechini aplicados às reações de oxidação de n-hexano

Oxide type spinel AB2O4 presents structure adjusted for application in the automobile industry. The spinel of cobalt has many practical applications had its excellent physical and chemical properties such as catalyst in hydrocarbon oxidation reaction. The CeO2 has been used in many of these processes because it assigns to a material with excellent thermal resistance and mechanics, high capacity of oxygen stockage (OSC) among others properties. This work deals with the synthesis, characterization and catalytic application of spinel of cobalt and CeO2 with fluorita structure, obtained for method of Pechini and method of Gel-Combustion. The process of Pechini, the puff was obtained at 300 ºC for 2 h in air. In the process of Gel-Combustion the approximately at 350 ºC material was prepared and burnt for Pyrolysis, both had been calcined at 500 ºC, 700 ºC, 900 ºC and 1050 ºC for 2 h in air. The materials of the calcinations had been characterized by TG/DTA, electronic microscopy of sweepings (MEV), spectroscopy of absorption in the infra-red ray (FTIR) and diffraction of X-rays (DRX). The obtained material reaches the phase oxide at 450 oC for Pechini method and 500 °C for combustion method. The samples were submitted catalytic reaction of n-hexane on superficies of materials. The reactor function in molar ration of 0, 85 mol.h-1.g-1 and temperature of system was 450 °C. The sample obtained for Pechini and support in alumine of superficial area of 178,63 m2.g-1 calcined at 700 ºC, give results of catalytic conversions of 39 % and the sample obtained for method of gel-combustion and support in alumina of 150 mesh calcined at 500 ºC result 13 % of conversion. Both method were selective specie C1

Análise mecânica e microestrutural das ligas de cobalto-cromo de uso odontológico após sucessivas refundições

The cobalt-chromium alloy is extensively used in the Odontology for the confection of metallic scaffolding in partial removable denture. During the last few years, it has been reported an increasing number of premature imperfections, with a few months of prosthesis use. The manufacture of these components is made in prosthetic laboratories and normally involves recasting, using parts of casting alloy and parts of virgin alloy. Therefore, the objective of the present study was to analyze the mechanical properties of a commercial cobalt-chromium alloy of odontological use after successive recasting, searching information to guide the dental prosthesis laboratories in the correct manipulation of the cobalt-chromium alloy in the process of casting and the possible limits of recasting in the mechanical properties of this material. Seven sample groups were confectioned, each one containing five test bodies, divided in the following way: G1: casting only with virgin alloy; G2: casting with 50% of the alloy of the G1 + 50% of virgin alloy; G3: casting with 50% of the alloy of the G2 + 50% of virgin alloy; G4: casting with 50% of the alloy of the G3 + 50% of virgin alloy; G5: 50% of alloy of the G4 + 50% of virgin alloy; G6: 50% of alloy of the G5 + 50% of virgin alloy and finally the G7, only with recasting alloy. The modifications in the mechanical behavior of the alloy were evaluated. Moreover, it was carried the micro structural characterization of the material by optic and electronic scanning microscopy, and X ray diffraction.and fluorescence looking into the correlatation of the mechanical alterations with structural modifications of the material caused by successive recasting process. Generally the results showed alterations in the fracture energy of the alloy after successive recasting, resulting mainly of the increasing presence of pores and large voids, characteristic of the casting material. Thus, the interpretation of the results showed that the material did not reveal significant differences with respect to the tensile strength or elastic limit, as a function of successive recasting. The elastic modulus increased from the third recasting cycle on, indicating that the material can be recast only twice. The fracture energy of the material decreased, as the number of recasting cycles increased. With respect to the microhardness, the statistical analyses showedno significant differences. Electronic scanning microscopy revealed the presence of imperfections and defects, resulting of the recasting process. X ray diffraction and fluorescence did not show alterations in the composition of the alloy or the formation of crystalline phases between the analyzed groups. The optical micrographs showed an increasing number of voids and porosity as the material was recast. Therefore, the general conclusion of this study is that the successive recasting of of Co-Cr alloys affects the mechanical properties of the material, consequently leading to the failure of the prosthetic work. Based on the results, the best recommendadition is that the use of the material should be limited to two recasting cycles

Otimização do processo de síntese do aluminato de cobalto via método de polimerização de complexos (MPC) através do planejamento fatorial fracionado

In the ceramics industry are becoming more predominantly inorganic nature pigments. Studies in this area allow you to develop pigments with more advanced properties and qualities to be used in the industrial context. Studies on synthesis and characterization of cobalt aluminate has been widely researched, cobalt aluminate behavior at different temperatures of calcinations, highlighting especially the temperatures of 700, 800 and 900° C that served as a basis in the development of this study, using the method of polymerization of complex (CPM), economic, and this method applied in ceramic pigment synthesis. The procedure was developed from a fractional factorial design 2 (5-2) in order to optimize the process of realization of the cobalt aluminate (CoAl2O4), having as response surfaces the batch analysis data of Uv-vis spectroscopy conducted from the statistic software 7.0, for this were chosen five factors as input variables: citric acid (stoichiometric manner), puff or pyrolysis time (h), temperature (° C), and calcinations (° C/min), at levels determined for this study. By applying statistics in the process of obtaining the CoAl2O4 is possible the study of these factors and which may have greater influence in getting the synthesis. The pigments characterized TG/DSC analyses, and x-ray diffraction (XRD) and scanning electron microscope (SEM/EDS) in order to establish the structural and morphological aspects of pigment CoAl2O4, among the factors studied it were found to statically with increasing calcinations temperature 700°< 800 <900 °C, the bands of Uv-vis decrease with increasing intensity of absorbance and that with increasing time of puff or pyrolysis (h) there is an increase in bands of Uv-vis proportionally, the generated model set for the conditions proposed in this study because the coefficient of determination can explain about 99.9% of the variance (R²), response surfaces generated were satisfactory, so it s possible applicability in the ceramics industry of pigments

Síntese de pigmento cerâmico ferrita de cobalto utilizando planejamento experimental

Synthetic inorganic pigments are the most widely used in ceramic applications because they have excellent chemical and thermal stability and also, in general, a lower toxicity to man and to the environment. In the present work, the ceramic black pigment CoFe2O4 was synthesized by the polymerization Complex method (MPC) in order to form a material with good chemical homogeneity. Aiming to optimize the process of getting the pigment through the MPC was used a fractional factorial design 2(5-2), with resolution III. The factors studied in mathematical models were: citric acid concentration, the pyrolysis time, temperature, time and rate of calcination. The response surfaces using the software statistica 7.0. The powders were characterized by thermal analysis (TG/DSC), x-ray diffraction (XRD), scanning electron microscopy (SEM) and spectroscopy in the UV-visible. Based on the results, there was the formation of phase cobalt ferrite (CoFe2O4) with spinel structure. The color of the pigments obtained showed dark shades, from black to gray. The model chosen was appropriate since proved to be adjusted and predictive. Planning also showed that all factors were significant, with a confidence level of 95%

Estudo da síntese e propriedade magnética de ferritas de manganês/cobalto dopadas com níquel

For the chemical method of synthesis of co-precipitation were produced ferrite powders manganese-cobalt equal stoichiometric formula Mn (1-x) Co (x) Fe2O4, for 0 < x < 1, first reagent element using as the hydroxide ammonium and second time using sodium hydroxide. The obtained powders were calcined at 400 ° C, 650 ° C, 900 ° C and 1150 ° C in a conventional oven type furnace with an air atmosphere for a period of 240 minutes. Other samples were calcined at a temperature of 900 ° C in a controlled atmosphere of argon, to evaluate the possible influence of the atmosphere on the final results the structure and morphology. The samples were also calcined in a microwave oven at 400 ° C and 650 ° C for a period of 45 minutes possible to evaluate the performance of this type of heat treatment furnace. It was successfully tested the ability of this group include isomorphic ferrite with the inclusion of nickel cations in order to evaluate the occurrence of disorder in the crystalline structures and their changes in magnetic characteristics.To identify the structural, morphological, chemical composition and proportions, as well as their magnetic characteristics were performed characterization tests of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDX), thermogravimetric (TG), vibrating sample magnetometry (MAV) and Mössbauer spectroscopy. These tests revealed the occurrence of distortion in the crystal lattice, changes in magnetic response, occurrence of nanosized particles and superparamagnetism

Teores de nutrientes na alface irrigada com água residuária aplicada por sistemas de irrigação

A trial was carried out to evaluate the chemical composition in the aerial part of lettuce, cv. 'Elisa', irrigated with wastewater treated with constructed wetland and source deposit water, grown on a Rhodic Hapludox Soil, using the irrigation systems sprinkle, subsurface drip and surface drip irrigation. The experiment was carried out from August 17th to October 3rd of 2001 and the chemical analyses of the lettuce were accomplished to 47 days after transplanting of the seedling. The aerial part of the lettuce was analyzed as for the levels of total nitrogen, nitrate, phosphorus, potassium, calcium, magnesium, sulfur, iron, manganese, copper, zinc, sodium, boron, cobalt and molybdenum. The sodium and the sulfur presented higher levels than the maximum suitable in the aerial part of the lettuce and the smallest level of magnesium, while other chemical elements analyzed were normal and appropriate considering the standard for well-nourished plants, not being influenced by the water type. The sodium was the chemical element that presented the highest levels in the aerial part of the lettuce in the treatments irrigated with wastewater, presenting significant difference in relationship to the treatments irrigated with source deposit water in the three irrigation systems. The use of the different irrigation systems by the application of wastewater treated with constructed wetland did not interfere in the levels of nutrients in the aerial part of the lettuce.

Effect of different cleansers on the surface of removable partial denture

Removable partial dentures (RPD) demand specific hygienic cleaning and the combination of brushing with immersion in chemical solutions has been the most recommended method for control of biofilm. However, the effect of the cleansers on metallic components has not been widely investigated. This study evaluated the effect of different cleansers on the surface of RPD. Five disc specimens (12 mm x 3 mm metallic disc centered in a 38 x 18 x 4 mm mould filled with resin) were obtained for each experimental situation: 6 solutions [Periogard (PE), Cepacol (CE), Corega Tabs (CT), Medical Interporous (MI), Polident (PO), 0.05% sodium hypochlorite (NaOCl), and distilled water (DW) control] and 2 Co-Cr alloys [DeguDent (DD) and VeraPDI (VPDI)] were used for each experimental situation. A 180-day immersion was simulated and the measurements of roughness (Ra, µm) of metal and resin were analyzed using 2-way ANOVA and Tukey’s test. The surface changes and tarnishes were examined with a scanning electronic microscopy (SEM). In addition, energy dispersive x-ray spectrometry (EDS) analysis was carried out at representative areas. Visually, NaOCl and MI specimens presented surface tarnishes. The roughness of materials was not affected by the solutions (p>0.05). SEM images showed that NaOCl and MI provided surface changes. EDS analysis revealed the presence of oxygen for specimens in contact with both MI and NaOCl solutions, which might suggest that the two solutions promoted the oxidation of the surfaces, thus leading to spot corrosion. Within the limitations of this study, it may be concluded that the NaOCl and MI may not be suitable for cleaning of RPD.