Adsorção dos gases NH3, NO e H2S em fosfato de vanadila, hidrogeno fosfato de vanadila e fosfatos de vanadila dopados por Al, Co, Mn e Cr

In this work were synthesized the materials called vanadyl phosphate, hydrogen vanadyl phosphate and vanadyl phosphate doped by transition metals with the aim in adsorption the following compounds: ammonia, hydrogen sulfide and nitrogen oxide. To characterize the starting compounds was used DRX, FTIR, FRX and TG analysis. After the characterization of substrates, proceeded de adsorption of NH3 and H2S gases in reactor, passing the gases with continuous flow for 30 min and room temperature. Gravimetric data indicate that the matrices of higher performance in adsorption of ammonia was those doped by aluminum and manganese, obtaining results of 216,77 mgNH3/g and 200,40 mgNH3/g of matrix, respectively. The matrice of higher performance in adsorption of hydrogen sulfide was that doped by manganese, obtaining results of 86,94 mgH2S/g of matrix. The synthesis of substrates VOPO4.2H2O and MnVOPO4.2H2O with nitrogen oxide was made in solution, aiming the final products VOPO4.G.nH2O and MnVOPO4.G.nH2O (G = NO and n = number of water molecules). The thermo analytical behavior and the infrared spectroscopy are indicative of formation of VOPO4.2,5NO.3H2O compound. Results of scanning electron microscopy (SEM) and Energy dispersive spectroscopy (EDS) of materials vanadyl phosphate and vanadyl phosphate modified after reaction in solid state or in solution with the gases show morphology changes in substrates, beyond the formation of orthorhombic sulfur crystals over their respective hosts when these adsorb hydrogen sulfide

Estudo de titanatos nanoestruturados obtidos por tratamento hidrotérmico de óxido de titânio em meio alcalino

TiTanate NanoTubes (TTNT) were synthesized by hydrothermal alkali treatment of TiO2 anatase followed by repeated washings with distinct degrees of proton exchange. TTNT samples with different sodium contents were characterized, as synthesized and after heattreatment (200-800ºC), by X-ray diffraction, scanning and transmission electron microscopy, electron diffraction, thermal analysis, nitrogen adsorption and spectroscopic techniques like FTIR and UV-Vis diffuse reflectance. It was demonstrated that TTNTs consist of trititanate structure with general formula NaxH2−xTi3O7·nH2O, retaining interlayer water in its multiwalled structure. The removal of sodium reduces the amount of water and contracts the interlayer space leading, combined with other factors, to increased specific surface area and mesopore volume. TTNTs are mesoporous materials with two main contributions: pores smaller than 10 nm due to the inner volume of nanotubes and larger pores within 5-60 nm attributed to the interparticles space. Chemical composition and crystal structure of TTNTs do not depend on the average crystal size of the precursor TiO2-anatase, but this parameter affects significantly the morphology and textural properties of the nanostructured product. Such dependence has been rationalized using a dissolution-recrystallization mechanism, which takes into account the dissolution rate of the starting anatase and its influence on the relative rates of growth and curving of intermediate nanosheets. The thermal stability of TTNT is defined by the sodium content and in a lower extent by the crystallinity of the starting anatase. It has been demonstrated that after losing interlayer water within the range 100-200ºC, TTNT transforms, at least partially, into an intermediate hexatitanate NaxH2−xTi6O13 still retaining the nanotubular morphology. Further thermal transformation of the nanostructured tri- and hexatitanates occurs at higher or lower temperature and follows different routes depending on the sodium content in the structure. At high sodium load (water washed samples) they sinter and grow towards bigger crystals of Na2Ti3O7 and Na2Ti6O13 in the form of rods and ribbons. In contrast, protonated TTNTs evolve to nanotubes of TiO2(B), which easily convert to anatase nanorods above 400ºC. Besides hydroxyls and Lewis acidity typical of titanium oxides, TTNTs show a small contribution of protonic acidity capable of coordinating with pyridine at 150ºC, which is lost after calcination and conversion into anatase. The isoeletric point of TTNTs was measured within the range 2.5-4.0, indicating behavior of a weak acid. Despite displaying semiconductor characteristics exhibiting typical absorption in the UV-Vis spectrum with estimated bandgap energy slightly higher than that of its TiO2 precursor, TTNTs showed very low performance in the photocatalytic degradation of cationic and anionic dyes. It was concluded that the basic reason resides in its layered titanate structure, which in comparison with the TiO2 form would be more prone to the so undesired electron-hole pair recombination, thus inhibiting the photooxidation reactions. After calcination of the protonated TTNT into anatase nanorods, the photocatalytic activity improved but not to the same level as that exhibited by its precursor anatase

Desenvolvimento de catalisadores bifuncionais de óxido de zircônio modificado por óxidos de tungstênio e molibdênio contendo platina para a reação de isomerização de n-parafinas

Bifunctional catalysts based on zircon oxide modified by tungsten (W = 10, 15 and 20 %) and by molybdenum oxide (Mo= 10, 15 e 20 %) containg platinum (Pt = 1%) were prepared by the polymeric precursor method. For comparison, catalysts the tungsten base was also prepared by the impregnation method. After calcinations at 600, 700 and 800 ºC, the catalysts were characterized by X-ray diffraction, fourier-transform infrared spectroscopy, thermogravimetric and differential thermal analysis, nitrogen adsorption and scanning electron microscopy. The profile of metals reduction was determined by temperature programmed reduction. The synthesized catalysts were tested in n-heptane isomerization. X-ray diffractogram of the Pt/WOx-ZrO2 and Pt/MoOx-ZrO2 catalysts revealed the presence of tetragonal ZrO2 and platinum metallic phases in all calcined samples. Diffraction peaks due WO3 and ZrO2 monoclinic also were observed in some samples of the Pt/WOx-ZrO2 catalysts. In the Pt/MoOx-ZrO2 catalysts also were observed diffraction peaks due ZrO2 monoclinic and Zr(MoO4)2 oxide. These phases contained on Pt/WOx-ZrO2 and Pt/MoOx-ZrO2 catalysts varied in accordance with the W or Mo loading and in accordance with the calcination temperature. The infrared spectra showed absorption bands due O-W-O and W=O bonds in the Pt/WOx-ZrO2 catalysts and due O-Mo-O, Mo=O and Mo-O bonds in the Pt/MoOx-ZrO2 catalysts. Specific surface area for Pt/WOx-ZrO2 catalysts varied from 30-160 m2 g-1 and for the Pt/MoOx-ZrO2 catalysts varied from 10-120 m2 g-1. The metals loading (W or Mo) and the calcination temperature influence directly in the specific surface area of the samples. The reduction profile of Pt/WOx-ZrO2 catalysts showed two peaks at lower temperatures, which are attributed to platinum reduction. The reduction of WOx species was evidenced by two reduction peak at high temperatures. In the case of Pt/MoOx-ZrO2 catalysts, the reduction profile showed three reduction events, which are attributed to reduction of MoOx species deposited on the support and in some samples one of the peak is related to the reduction of Zr(MoO4)2 oxide. Pt/WOx-ZrO2 catalysts were active in the n-heptane isomerization with high selectivity to 3-methyl-hexane, 2,3- dimethyl-pentane, 2-methyl-hexane among other branched hydrocarbons. The Pt/MoOx-ZrO2 catalysts practically didn't present activity for the n-heptane isomerization, generating mainly products originating from the catalytic cracking

Efeito dos nutrientes (nitrogênio e fósforo) sobre o desenvolvimento da Gracilaria birdiae: crescimento e possível uso como biofiltro

Marine shrimp farming has grown exponentially during the last years in Brazil. In spite of the promising economical situation, this activity is facing an increasing criticism due to its environmental impact. Thus, the necessity of alternatives to mitigate environmental degradation caused by this activity. An alternative that is being studied is the policulture that is the integrated culture of two or more organisms, normally one of them a filtering organism. Among filtering organisms, macroalgae are very practicable because they are efficient in the removal of the exceeding nutrients of the water and do not leave residues in the water. Besides, the integrated culture with macroalgae allows the economical exploration of the seaweed (for the manufacture of jelly and jam, for the dairy industry, pharmaceuticals, etc.) along with possibility of a sustainable aquaculture. In the present experiment, the development of the seaweed Gracilaria birdiae, the influence and tolerance of this species to the environmental parameters, and its absorption efficiency in relation with the three kinds of macronutrients (NH4+, NO3- and PO4-3) found in the effluents of marine shrimp farming was studied. The experiment was divided in two parts: a laboratorial part and one part carried under natural conditions. The water used in the laboratory trial was collected in the shrimp ponds of Tecnarão farm and distributed in aquaria containing 20 g of G. birdiae. In the field trial, 0.5 kg of G. birdiae was inserted in PVC cages cultivated in the farm. The results of the study showed a modest growth of G. birdiae, probably due to its low tolerance to highly eutrophicated environments. However, the removal of nutrients was very expressive. Ammonia was reduced in approximately 34 %. Ortho-phosphate showed a reduction of 93.5 %. The capacity of biofiltration of the NO3- by the macro algae was of 100 %, showing that G. birdiae is a seaweed-filtered with a high level of removal for this nutrient under laboratorial conditions. In spite of the low growth of the macro algae in the experiment, the results in relation to the removal of nutrients of the water was encouraging, suggesting that this species can be an efficient biofilter and thus, a strong candidate to be used in a sustainable aquaculture

Regulação da mobilização de lipídios e proteinas por hormônios, fontes de carbono e nitrogênio durante o crescimento pos-germinativo em girassol

The mobilization of food reserves in storage tissues and allocation of their hydrolysis products in the growing axis are critical processes for the establishment of seedlings after germination. Therefore, it is crucial for mobilization of reserves to be synchronized with the growing axis, so that photosynthetic activity can be started before depletion of reserves. For this, integrative approaches involving different reserves, different hydrolysis products and interaction between storage and growing axis tissues, either through hormones or metabolites with signaling role, can contribute greatly to the elucidation of the regulation mechanisms for reserve mobilization. In this study, was hypothesized that hormones and metabolites have different actions on reserve mobilization, and there must be a crossed effect of sugars on the mobilization of proteins and amino acids on lipids and starch mobilization in sunflower seedlings. This study was conducted with seeds of sunflower (Helianthus annuus L.) hybrid Helio 253 using in vitro culture system. Seeds were germinated on Germitest® paper and grown on agar-water 4 g/L without addition of nutrients during 9 days after imbibition (DAI) for growth curve. To verify the effect of metabolites and hormones, seedlings were transferred in the 2nd DAI to agar-water 4 g/L supplemented with increasing concentrations of sucrose or L-glutamine, abscisic acid, gibberellic acid or indolebutyric acid. The results of this study confirm that the mobilization of lipids and storage proteins occurs in a coordinated manner during post-germination growth in sunflower, corroborating the hypothesis that the application of external carbon (sucrose) and nitrogen (L-glutamine) sources can delay the mobilization of these reserves in a crossed way. Moreover, considering the changes in the patterns of reserve mobilization and partition of their products in seedlings treated with different growth regulators, it is evident that the effects of metabolites and hormones must involve, at least in part, distinct mechanisms of action

Síntese e caracterização de TaC e óxido misto de tântalo e cobre nanoestruturados a partir do precursor oxálico de tântalo através de reações gás-sólido e sólido-sólido a baixa temperatura

The research and development of nanostructured materials have been growing significantly in the last years. These materials have properties that were significantly modified as compared to conventional materials due to the extremely small dimensions of the crystallites. The tantalum carbide (TaC) is an extremely hard material that has high hardness, high melting point, high chemical stability, good resistance to chemical attack and thermal shock and excellent resistance to oxidation and corrosion. The Compounds of Tantalum impregnated with copper also have excellent dielectric and magnetic properties. Therefore, this study aimed to obtain TaC and mixed tantalum oxide and nanostructured copper from the precursor of tris (oxalate) hydrate ammonium oxitantalato, through gas-solid reaction and solid-solid respectively at low temperature (1000 ° C) and short reaction time. The materials obtained were characterized by X-ray diffraction (XRD), Rietveld refinement, Scanning Electron Microscopy (SEM), Spectroscopy X-Ray Fluorescence (XRF), infrared spectroscopy (IR), thermogravimetric (TG), thermal analysis (DTA) and BET. Through the XRD analyses and the Reitiveld refinement of the TaC with S = 1.1584, we observed the formation of pure tantalum carbide and cubic structure with average crystallite size on the order of 12.5 nanometers. From the synthesis made of mixed oxide of tantalum and copper were formed two distinct phases: CuTa10O26 and Ta2O5, although the latter has been formed in lesser amounts

Preparação e caracterização de filmes cerâmicos para cátodos de células a combustível de óxido sólido

Alternative and clean energy generation research has been intensified in last decades. Among the alternatives, fuel cells are one of the most important. There are different types of fuel cells, among which stands out intermediate temperature solid oxide fuel cell (IT-SOFC) matter of the present work. For application as cathode on this type of devices, the ceramic Ba0.5Sr0.5C0.8Fe0.2O3-δ doped with rare earth ions (Nd, Sm) have been quite promising because they show good ionic conductivity and operate at relatively low temperatures (500 - 800°C). In this work, Ba0.5Sr0.5Co0.8Fe0.2O3-δ, (BaSr)0.5Sm0.5Co0.8Fe0.2O3-δ and (BaSr)0.5Nd0.5C0.8Fe0.2O3-δ were obtained by modified Pechini method, making use of gelatin as polymerizing agent. The powders were characterized by X-Ray Diffraction (XRD), Temperature Programmed Reduction (TPR) and Scanning Electron Microscopy (SEM). The perovskite phase was observed in all X-ray patterns for the materials Ba0.5Sr0.5C0.8Fe0.2O3-δ doped with rare earth ions (Nd, Sm). The SEM images showed that the materials have a characteristics porous, with very uniform pore distribution, which are favorable for application as cathodes. Subsequently, screen-printed assymmetrical cells were studied by impedance spectroscopy, to assess the kinetics of the cathode for the reduction reaction of oxygen. The best resistance to the specific area was found for the cathode BSSCF sintered at 1050 °C for 4 hours with around 0.15 Ω.cm2 at 750 °C as well as cathodes BSNCF and BSCF obtained resistances specific area of 0.2 and 0.73 Ω.cm2, respectively, for the same conditions. The polarization curves showed similar behavior to the best cathodes BSSCF and BSNCF, such combination of properties indicates that the film potentially depict good performance as IT-SOFC cathodes

Redução aluminotérmica do óxido de tântalo usando uma tocha de plasma como ignitor

In this work was used a plasma torch of non transferred arc with argon as work gas, using a power supply with maximum DC current of 250 A and voltage of 30 V to activate the plasma and keep it switched on. The flame temperature was characterized by optical emission spectroscopy, through Boltzmann-plot-method. The torch has been used like igniter in the aluminothermic reduction of the mixture tantalum oxide and aluminum, seeking to obtain metallic tantalum. In heating of the reagents only one particle will be considered to study interactions between plasma-particle, seeking to determinate its fusion and residence time. The early powders were characterized by laser granulometry, scanning electron microscopy (SEM) and X-ray diffraction analysis. The final product of this reaction was characterized by SEM and X-ray diffraction. Crystallite size was calculated by the Scherrer equation and microdeformation was determined using Willamsom-Hall graph. With Rietveld method was possible to quantify the percentile in weight of the products obtained in the aluminothermic reaction. Semi-quantitative chemical analysis (EDS) confirmed the presence of metallic tantalum and Al2O3 as products of the reduction. As was waited the particle size of the metallic tantalum produced, presents values in nanometric scale due the short cooling time of those particles during the process

Estudo comparativo da utilização do nitrogênio como fluido alternativo após a injeção de vapor

Currently, due to part of world is focalized to petroleum, many researches with this theme have been advanced to make possible the production into reservoirs which were classified as unviable. Because of geological and operational challenges presented to oil recovery, more and more efficient methods which are economically successful have been searched. In this background, steam flood is in evidence mainly when it is combined with other procedures to purpose low costs and high recovery factors. This work utilized nitrogen as an alternative fluid after steam flood to adjust the best combination of alternation between these fluids in terms of time and rate injection. To describe the simplified economic profile, many analysis based on liquid cumulative production were performed. The completion interval and injection fluid rates were fixed and the oil viscosity was ranged at 300 cP, 1.000 cP and 3.000 cP. The results defined, for each viscosity, one specific model indicating the best period to stop the introduction of steam and insertion of nitrogen, when the first injected fluid reached its economic limit. Simulations in physics model defined from one-eighth nine-spot inverted were realized using the commercial simulator Steam, Thermal and Advanced Processes Reservoir Simulator STARS of Computer Modelling Group CMG

Análise do óxido nítrico, perfil lipídico, resistência arterial e capacidade funcional de idosas submetidas a um treinamento aquático

A prática regular de exercício físico possibilita redução dos efeitos das disfunções hormonais e envelhecimento biológico natural que promovem desajustes hemodinâmicos, vasculares e músculo-esqueléticos, principalmente na população feminina no período pós-menopausa. Nesta fase da vida, o exercício aquático representa mais do que uma forma de ajuste funcional, é uma forma de manutenção de independência para as atividades da vida diária (AVD s) e melhoria na qualidade de vida. Este estudo teve como objetivo avaliar as modificações adquiridas pela prática regular de um programa de exercício aquático concorrente de intensidade moderada no nível de óxido nítrico (ON), no índice de resistividade arterial (IR), no perfil lipídico, na capacidade funcional e na qualidade de vida de idosas. A amostra foi formada por idosas (60 a 80 anos) selecionadas por randomização, por sorteio simples divididas em grupo controle e grupo de intervenção as quais foram submetidas a um programa de exercícios aquáticos proposto inicialmente em projeto piloto, por 12 semanas (n=34) e o ensaio clínico teve duração de 16 semanas (n=40). Foi coletada amostra sanguínea das idosas e avaliado o perfil lipídico pelo método enzimático com kit Labtest e o ON por medida indireta a partir da concentração de nitrito no sobrenadante das células em cultura em leitor de ELISA. A avaliação das artérias carótidas e vertebrais foi feita utilizando o método de ultra-som Doopler. A capacidade funcional foi avaliada por quatro testes que simulam atividades da vida diária que são: caminhar 10 metros (C10m), levantar da posição sentada (LPS), levantar da cadeira e locomover-se pela casa (LCLC) e o de levantar-se da posição decúbito ventral (LPDV). No estudo piloto foi avaliado o índice geral de autonomia funcional (IG) e a qualidade de vida através do questionário WHOQOL-100. Empregou-se a análise de variância (ANOVA) com medidas repetidas nos fatores grupo (GH e GC) e tempo (pré e pós-teste) para as comparações intra e intergrupos nas variáveis seguida do post hoc de Scheffé. Utilizou-se o teste de correlação de Pearson e adotado o valor de p<0,05 para a significância estatística. Houve aumento do ON circulante, redução nos índices de resistividade arterial, melhoria significativa nos níveis de colesterol e triglicérides e ganho na capacidade funcional das idosas após a intervenção. Existiu correlação inversa entre a resistividade da artéria vertebral direita (VERTD) e níveis de ON e entre a VERTD e os níveis plasmáticos de HDL, assim como entre estes e o teste C10m nas idosas em estudo. Não houve modificações significativas na qualidade de vida das idosas. Em conclusão, o programa de exercício proposto foi capaz de oferecer melhorias funcionais, aumentar o nível de óxido nítrico circulante, diminuindo a resistência arterial promovendo modificações no perfil lipídico de idosas

Contribuições sobre estudos térmicos (TG/DTG, DTA, DSC e DSC-Fotovisual) da rifampicina e seus principais produtos de degradação

Since its synthesis over 48 years rifampicin has been extensively studied. The literature reports the characterization of thermal events for rifampicin in nitrogen atmosphere, however, no characterization in synthetic air atmosphere. This paper aims to contribute to the thermal study of rifampicin through thermal (TG / DTG, DTA, DSC and DSC - FOTOVISUAL ) and non-thermal (HPLC, XRPD , IR - FTIR , PCA) and its main degradation products ( rifampicin quinone , rifampicin N-oxide 3- formylrifamicin). Rifampicin study was characterized as polymorph form II from techniques DSC, IR and XRPD. TG curves for rifampicin in synthetic air atmosphere showed higher thermal stability than those in N2, when analyzed Ti and Ea. There was characterized as overlapping events melting and recrystallization under N2 with weight loss in the TG curve, suggesting concomitant decomposition. Images DSCFotovisual showed no fusion event and showed darkening of the sample during analysis. The DTA curve in synthetic air atmosphere was visually different from DTA and DSC curves under N2, suggesting the absence of recrystallization and melting or presence only decomposition. The IV - FTIR analysis along with PCA analysis and HPLC and thermal data suggest that rifampicin for their fusion is concomitant decomposition of the sample in N2 and fusion events and recrystallization do not occur in synthetic air atmosphere. Decomposition products studied in an air atmosphere showed no melting event and presented simultaneously to the decomposition initiation of heating after process loss of water and / or solvent, varying the Ti initiating events. The Coats - Redfern , Madsudhanan , Van Krevelen and Herwitz - Mertzger kinetic parameters for samples , through the methods of OZAWA , in an atmosphere of synthetic air and / or N2 rifampicin proved more stable than its degradation products . The kinetic data showed good correlation between the different models employed. In this way we contribute to obtaining information that may assist studies of pharmaceutical compatibility and stability of substances

Obtenção de cerâmicas à base de tricálcio fosfatos utilizando óxido de magnésio como aditivo

The tricalcium phosphate ceramics has been widely investigated in the last years due its bioresorbable behavior. The limiting factor of the application of these materials as temporary implants is its low strength resistance. The tricalcium phosphate presents an allotropic transformation β→α around 1250 ºC that degrades its resistance. Some studies have been developed in order to densify this material at this temperature range. The objective of this work is to study the influence of the addition of magnesium oxide (MgO) in the sintering of β-TCP. The processing route was uniaxial hot pressing and its objective was to obtain dense samples. The samples were physically characterized through density and porosity measurements. The thermal behavior was studied through dilatometric, thermal differential and thermogravimetric analysis. The mechanical properties were characterized by three point flexure test and Vickers microhardness measurements, analyzed of the microstructure. The addition of magnesium oxide doesn t cause an improvement of the mechanical strength in relation to material without additive.

Obtenção de cerâmicas à base de tricálcio fosfatos utilizando óxido de manganês como aditivo

The calcium phosphate ceramics have been very investigated as material for bone implants. The tricalcium phosphate (β-TCP) had a great potential for application in temporary implants like a resorbable bioceramic. This material presents a limitation in its sintering temperature due to occurrence of the allotropic transformation β → α at temperatures around 1200°C, not allowing the attainment of dense ceramic bodies. This transformation also causes cracks, what diminishes the mechanical strength, limiting its use to applications of low mechanical requests. This work studies the influence of the addition of manganese oxide in the sintering of β-TCP. Two processing routes were investigated. The first was the powder metallurgy conventional process. The test bodies (samples) were pressed and sintering at temperatures of 1200 and 1250°C. The second route was uniaxial hot pressing and its objective was to obtain samples with high relative density. The samples were physically characterized through density and porosity measurements. The thermal behavior was studied through dilatometric, thermal differential and thermogravimetric analysis. The mechanical properties were characterized by three point flexure test and Vickers microhardness measurements. The microstructure was analyzed by scanning electron microscopy. The addition of manganese oxide caused an improvement of the mechanical strength in relation to the material without additive and promoting the stabilization of β-TCP to greater temperatures

Estudo do efeito do óxido de bário no comportamento de massas para porcelanato

In this work, it is proposed the study of the effect of barium oxide acting as synthetic flow in the behavior of masses for stoneware from the use of raw materials found in the deposits of minerals of the Rio Grande do Norte that it makes use of a great natural potential for the industrialization of the product. The porcelanato is a sophisticated product with excellent final properties being applied as ceramic coating in buildings of high standard of engineering. The raw materials selected for the development of the study had been two types of argilas, two types of feldspatos, dolomita, talco, barium carbonate and silica, being characterized by X-ray fluorescence, X-ray diffraction, granulometric analysis, dilatometric analysis and thermal analysis. Thus, it is intended to define four formulations using the cited raw materials that will be processed, conformed and sintered in the temperatures of 1150 °C, 1175 °C, 1200 °C, 1225 °C e 1250 °C. From the physical characterizations, chemical and morphologic of the formed formulations, the effect of barium oxide is determined in the physical and mechanical properties of the studied system carrying water absorption tests, linear retraction, apparent porosity, apparent specific mass, compacting curve, flexural strength and microstructural analysis by XRD and SEM. After analyzing the results, indicated that barium oxide acts as a flux of high temperature and as the ordering of structure, where the embedded glass phase has the nucleating effect phase potassium silico-aluminum reacting with free silica which together with the high content of potassium concentrated form a new crystalline phase called microcline. The masses studied with the addition of barium oxide present physical-mechanical properties highly satisfactory in reduced firing temperatures, which implies a saving in energy given off in the production and increased productivity

Redução carbotérmica de TiO2 por descarga em cátodo oco

In this study we used the plasma as a source of energy in the process of carbothermic reduction of rutile ore (TiO2). The rutile and graphite powders were milled for 15 h and placed in a hollow cathode discharge produced by in order to obtain titanium carbonitride directly from the reaction, was verified the influence of processing parameters of plasma temperature and time in the synthesis of TiCN. The reaction was carried out at 600, 700 and 800˚C for 3 to 4 hours in an atmosphere of nitrogen and argon. During all reactions was monitored by plasma technique of optical emission spectroscopy (EEO) to check the active species present in the process of carbothermal reduction of TiO2. The powder obtained after the reactions were characterized by the techniques of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The technique of EEO were detected in all reactions the spectra CO and NO, and these gas-phase resulting from the reduction of TiO2. The results of X-ray diffraction confirmed the reduction, where for all conditions studied there was evidence of early reduction of TiO2 through the emergence of intermediate oxides. In the samples reduced at 600 and 700˚C, there was only the phase Ti6O11, those reduced to 800˚C appeared Ti5O9 phases, and Ti6O11 Ti7O13, confirming that the carbothermal reduction in plasma, a reduction of the ore rutile (TiO2) in a series of intermediate titanium oxide (TinO2n-1) where n varies between 5 and 10