Elaboração de pós de ferrita de cobalto, CoFe2O4, nanoestruturados e hierarquizados: influência da morfologia sobre a detecção e oxidação catalítica de gases poluentes

This thesis is part of research on new materials for catalysis and gas sensors more active, sensitive, selective. The aim of this thesis was to develop and characterize cobalt ferrite in different morphologies, in order to study their influence on the electrical response and the catalytic activity, and to hierarchize these grains for greater diffusivity of gas in the material. The powders were produced via hydrothermal and solvothermal, and were characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy (electron diffraction, highresolution simulations), and energy dispersive spectroscopy. The catalytic and electrical properties were tested in the presence of CO and NO2 gases, the latter in different concentrations (1-100 ppm) and at different temperatures (room temperature to 350 ° C). Nanooctahedra with an average size of 20 nm were obtained by hydrothermal route. It has been determined that the shape of the grains is mainly linked to the nature of the precipitating agent and the presence of OH ions in the reaction medium. By solvothermal method CoFe2O4 spherical powders were prepared with grain size of 8 and 20 nm. CoFe2O4 powders exhibit a strong response to small amounts of NO2 (10 ppm to 200 ° C). The nanooctahedra have greater sensitivity than the spherical grains of the same size, and have smaller response time and shorter recovery times. These results were confirmed by modeling the kinetics of response and recovery of the sensor. Initial tests of catalytic activity in the oxidation of CO between temperatures of 100 °C and 350 °C show that the size effect is predominant in relation the effect of the form with respect to the conversion of the reaction. The morphology of the grains influence the rate of reaction. A higher reaction rate is obtained in the presence of nanooctahedra. In order to improve the detection and catalytic properties of the material, we have developed a methodology for hierarchizing grains which involves the use of carbonbased templates.

Aplicação da destilação simulada por cromatografia gasosa e da termogravimetria para a avaliação da influência da redução do teor de enxofre sobre as propriedades físico-químicas do óleo diesel

One of the main problems related to the use of diesel as fuel is the presence of sulfur (S) which causes environmental pollution and corrosion of engines. In order to minimize the consequences of the release of this pollutant, Brazilian law established maximum sulfur content that diesel fuel may have. To meet these requirements, diesel with a maximum sulfur concentration equal to 10 mg/kg (S10) has been widely marketed in the country. However, the reduction of sulfur can lead to changes in the physicochemical properties of the fuel, which are essential for the performance of road vehicles. This work aims to identify the main changes in the physicochemical properties of diesel fuel and how they are related to reduction of sulfur content. Samples of diesel types S10, S500 and S1800 were tested according with the methods of the American Society for Testing and Materials (ASTM). The fuels were also characterized by thermogravimetric analysis (TG) and subjected to physical distillation (ASTM D86) and simulated distillation gas chromatography (ASTM D2887). The results showed that the reduction of sulfur turned the fuel lighter and fluid, allowing a greater applicability to low temperature environments and safer for transportation and storage. Through the simulated distillation data was observed that decreasing sulfur content resulted in higher initial boiling point temperatures and the decreasing of the boiling temperature of the medium and heavy fractions. Thermogravimetric analysis showed a loss event mass attributed to volatilization or distillation of light and medium hydrocarbons. Based on these data, the kinetic behavior of the samples was investigated and it was observed that the activation energies (Ea) did not show significant changes throughout conversion. Considering the average of these energies, the S1800 had the highest Ea during the conversion and the S10 the lowest values

Síntese e caracterização de materiais mesoporosos para a captura de CO2: influência do óxido de níquel

Several materials are currently under study for the CO2 capture process, like the metal oxides and mixed metal oxides, zeolites, carbonaceous materials, metal-organic frameworks (MOF's) organosilica and modified silica surfaces. In this work, evaluated the adsorption capacity of CO2 in mesoporous materials of different structures, such as MCM-48 and SBA- 15 without impregnating and impregnated with nickel in the proportions 5 %, 10 % and 20 % (m/m), known as 5Ni-MCM-48, 10Ni-MCM-48, 20Ni-MCM-48 and 5Ni-SBA-15, 10NiSBA-15, 20Ni-SBA-15. The materials were characterized by means of X-ray diffraction (XRD), thermal analysis (TG and DTG), Fourier transform infrared spectroscopy (FT-IR), N2 adsorption and desorption (BET) and scanning electron microscopy (SEM) with EDS. The adsorption process was performed varying the pressure of 100 - 4000 kPa and keeping the temperature constant and equal to 298 K. At a pressure of 100 kPa, higher concentrations of adsorption occurred for the materials 5Ni-MCM-48 (0.795 mmol g-1 ) and SBA-15 (0.914 mmol g-1 ) is not impregnated, and at a pressure of 4000 kPa for MCM-48 materials (14.89 mmol g-1) and SBA-15 (9.97 mmol g-1) not impregnated. The results showed that the adsorption capacity varies positively with the specific area, however, has a direct dependency on the type and geometry of the porous structure of channels. The data were fitted using the Langmuir and Freundlich models and were evaluated thermodynamic parameters Gibbs free energy and entropy of the adsorption system

Modelagem e simulação da solubilidade de sais em sistemas aquosos com Monoetilenoglicol

Primary processing of natural gas platforms as Mexilhão Field (PMXL-1 ) in the Santos Basin, where monoethylene glycol (MEG) has been used to inhibit the formation of hydrates, present operational problems caused by salt scale in the recovery unit of MEG. Bibliographic search and data analysis of salt solubility in mixed solvents, namely water and MEG, indicate that experimental reports are available to a relatively restricted number of ionic species present in the produced water, such as NaCl and KCl. The aim of this study was to develop a method for calculating of salt solubilities in mixed solvent mixtures, in explantion, NaCl or KCl in aqueous mixtures of MEG. The method of calculating extend the Pitzer model, with the approach Lorimer, for aqueous systems containing a salt and another solvent (MEG). Python language in the Integrated Development Environment (IDE) Eclipse was used in the creation of the computational applications. The results indicate the feasibility of the proposed calculation method for a systematic series of salt (NaCl or KCl) solubility data in aqueous mixtures of MEG at various temperatures. Moreover, the application of the developed tool in Python has proven to be suitable for parameter estimation and simulation purposes

Análise espacial de reservatórios usando DFA de dados geofísicos

This research aims to set whether is possible to build spatial patterns over oil fields using DFA (Detrended Fluctuation Analysis) of the following well logs: sonic, density, porosity, resistivity and gamma ray. It was employed in the analysis a set of 54 well logs from the oil field of Campos dos Namorados, RJ, Brazil. To check for spatial correlation, it was employed the Mantel test between the matrix of geographic distance and the matrix of the difference of DFA exponents of the well logs. The null hypothesis assumes the absence of spatial structures that means no correlation between the matrix of Euclidean distance and the matrix of DFA differences. Our analysis indicate that the sonic (p=0.18) and the density (p=0.26) were the profiles that show tendency to correlation, or weak correlation. A complementary analysis using contour plot also has suggested that the sonic and the density are the most suitable with geophysical quantities for the construction of spatial structures corroborating the results of Mantel test

Obtenção de Mo2C com adição de Co por reação gás-sólido em reator de leito fixo

Sulfur compounds emissions have been, on the late years, subject to more severe environmental laws due to its impact on the environment (causing the acid rain phenomena) and on human health. It has also been object of much attention from the refiners worldwide due to its relationship with equipment’s life, which is decreased by corrosion, and also with products’ quality, as the later may have its color, smell and stability altered by the presence of such compounds. Sulfur removal can be carried out by hydrotreating (HDT) which is a catalytic process. Catalysts for HDS are traditionally based on Co(Ni)-Mo(W)/Al2O3. However, in face of the increased contaminants’ content on crude oil, and stricter legislation on emissions, the development of new, more active and efficient catalysts is pressing. Carbides of refractory material have been identified as potential materials for this use. The addition of a second metal to carbides may enhance catalytic activities by increasing the density of active sites. In the present thesis Mo2C with Co addition was produced in a fixed bed reactor via gas-solid reaction of CH4 (5%) and H2(95%) with a precursor made of a mix of ammonium heptamolybdate [(NH4)6[Mo7O24].4H2O] and cobalt nitrate[Co(NO3)2.6H2O] at stoichiometric amounts. Precursors’ where analyzed by XRF, XRD, SEM and TG/DTA. Carboreduction reactions were carried out at 700 and 750°C with two cobalt compositions (2,5 and 5%). Reaction’s products were characterized by XRF, XRD, SEM, TOC, BET and laser granulometry. It was possible to obtain Mo2C with 2,5 and 5% cobalt addition as a single phase at 750°C with nanoscale crystallite sizes. At 700°C, however, both MoO2 and Mo2C phases were found by XRD. No Co containing phases were found by XRD. XRF, however, confirmed the intended Co content added. SEM images confirmed XRD data. The increase on Co content promoted a more severe agglomeration of the produced powder. The same effect was noted when the reaction temperature was increased. The powder synthesized at 750°C with 2,5% Co addition TOC analysis indicated the complete conversion from oxide material to carbide, with a 8,9% free carbon production. The powder produced at this temperature with 5% Co addition was only partially converted (86%)

Avaliação térmica e desempenho do processo de secagem de misturas de graviola e leite em secador de leito de jorro

The soursop (A. muricata) is a fruit rich in minerals especially the potassium content. The commercialization of soursop in natura and processed has increased greatly in recent years. Drying fruit pulp in order to obtain the powdered pulp has been studied, seeking alternatives to ensure the quality of dehydrated products at a low cost of production. The high concentration of sugars reducing present in fruits causes problems of agglomeration and retention during fruit pulp drying in spouted bed dryers. On the other hand in relation to drying of milk and fruit pulp with added milk in spouted bed, promising results are reported in the literature. Based on these results was studied in this work drying of the pulp soursop with added milk in spouted bed with inert particles. The tests were based on a 24 factorial design were evaluated for the effects of milk concentration (30 to 50% m/m), drying air temperature (70 to 90 °C), intermittency time (10 to 14 min), and ratio of air velocity in relation to the minimum spout (1.2 to 1.5) on the rate of production, of powder moisture, yield, rate of drying and thermal efficiency of the process. There were physical and chemical analysis of mixtures, of powders and of mixtures reconstituted by rehydration powders. Were adjusted statistical models of first order to data the rate of production, yield and thermal efficiency, that were statistically significant and predictive. An efficiency greater than 40% under the conditions of 50% milk mixture, at 70 ° C the drying air temperature and 1.5 for the ratio between the air velocity and the minimum spout has been reached. The intermittency time showed no significant effect on the analyzed variables. The final product had moisture in the range of 4.18% to 9.99% and water activity between 0.274 to 0.375. The mixtures reconstituted by rehydration powders maintained the same characteristics of natural blends.

Extração do corante do fruto de castanhola (Terminalia catappa Linn) e estudos dos seus compostos fenólicos, antocianinas e atividade antioxidante

The Terminalia catappa Linn belonging to Combretaceae family, popularly known as castanets, has fruits consists of a fleshy pulp, rounded seed and a very hard shell. The natural pigmentation existing in the fruit of castanet indicates the presence of anthocyanins, phenolic nature components belonging to the group of flavonoids, which have antioxidant activity. This research was conducted with the castanets and aimed to the study of factors influencing the extraction of dyes from its pulp. The extracts were obtained using a reactor enjaquetado by solid-liquid extraction. The factors were evaluated as temperature, time, solvent ratio and pH extraction. Adopting a factorial design of 24 , with 4 repetitions at the central point, the effects of these factors on the extraction process were analyzed using Statistica 7.0 software. The antioxidant activity (AA), the content of phenolic compounds (CFT) and the total monomeric anthocyanin content (AMT) were evaluated as response variables planning. Statistical analysis of the results, the effects that influenced the extraction were different for each response (CFT, AMT and AA). However, the pH was significant for the extraction of all compounds. The kinetic behavior of the dye extraction was also studied for phenolic compounds, monomeric anthocyanins and antioxidant activity, in which the equilibrium was reached after 90 minutes of extraction. To study the stability of anthocyanins temperature was the factor that most influenced the stability, however the concentration and pH also played a part.

Estudo experimental e modelagem do processo de sacarificação e fermentação simultânea utilizando bagaço de cana-de-açúcar para produção de etanol

Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq

Desenvolvimento de novos biolubrificantes hidráulicos derivados dos óleos de maracujá e de moringa in natura e epoxidados

With the increasing environmental awareness, maximizing biodegradability and minimizing ecotoxicity is the main driving force for new technological developments. Thus, can be developed new biodegradable lubricants for use in environmentally sensitive areas. The aim of this study was to obtain new bio-lubricants from passion fruit (Passiflora edulis Sims f. flavicarpa Degener) and moringa (Moringa oleifera Lamarck) epoxidized oils and develop a new additive package using experimental design for their use as a hydraulic fluid. In the first stage of this work was performed the optimization of the epoxidation process of the oils using fractional experimental design 24-1 , varying the temperature, reaction time, ratio of formic acid and hydrogen peroxide. In the second step was investigated the selectivity, thermodynamics and kinetics of the reaction for obtaining the two epoxides at 30, 50 and 70 °C. The result of the experimental design confirmed that the epoxidation of passion fruit oil requires 2 hours of reaction, 50 °C and a ratio H2O2/C=C/HCOOH (1:1:1). For moringa oil were required 2 hours reaction, 50 °C and a ratio of H2O2/C=C/HCOOH (1:1:1.5). The results of the final conversions were equal to 83.09% (± 0.3) for passion fruit oil epoxide and 91.02 (±0,4) for moringa oil epoxide. Following was made the 23 factorial design to evaluate which are the best concentrations of corrosion inhibitor and anti-wear (IC), antioxidant (BHA) and extreme pressure (EP) additives. The bio-lubricants obtained in this step were characterized according to DIN 51524 (Part 2 HLP) and DIN 51517 (Part 3 CLP) standards. The epoxidation process of the oils was able to improve the oxidative stability and reduce the total acid number, when compared to the in natura oils. Moreover, the epoxidized oils best solubilized additives, resulting in increased performance as a lubricant. In terms of physicochemical performance, the best lubricant fluid was the epoxidized moringa oil with additives (EMO-ADI), followed by the epoxidized passion fruit oil with additives (EPF-ADI) and, finally, the passion fruit in natura oil without additives (PFO). Lastly, was made the investigation of the tribological behavior under conditions of boundary lubrication for these lubricants. The tribological performance of the developed lubricants was analyzed on a HFRR equipment (High Frequency Reciprocating Rig) and the coefficient of friction, which occurs during the contact and the formation of the lubricating film, was measured. The wear was evaluated through optical microscopy and scanning electron microscopy (SEM). The results showed that the addition of extreme pressure (EP) and anti-wear and corrosion inhibitor (CI) additives significantly improve the tribological properties of the fluids. In all assays, was formed a lubricating film that is responsible for reducing the coefficient of metal-to-metal wear. It was observed that the addition of EP and IC additives in the in natura vegetable oils of passion fruit and moringa did not favor a significant reduction in wear. The bio-lubricants developed from passion fruit and moringa oils modified via epoxidation presented satisfactory tribological properties and shown to be potential lubricants for replacement of commercial mineral-based fluids.

Uso de água produzida na formulação de fluidos de perfuração

Drilling fluids have fundamental importance in the petroleum activities, since they are responsible for remove the cuttings, maintain pressure and well stability, preventing collapse and inflow of fluid into the rock formation and maintain lubrication and cooling the drill. There are basically three types of drilling fluids: water-based, non-aqueous and aerated based. The water-based drilling fluid is widely used because it is less aggressive to the environment and provide excellent stability and inhibition (when the water based drilling fluid is a inhibition fluid), among other qualities. Produced water is generated simultaneously with oil during production and has high concentrations of metals and contaminants, so it’s necessary to treat for disposal this water. The produced water from the fields of Urucu-AM and Riacho da forquilha-RN have high concentrations of contaminants, metals and salts such as calcium and magnesium, complicating their treatment and disposal. Thus, the objective was to analyze the use of synthetic produced water with similar characteristics of produced water from Urucu-AM and Riacho da Forquilha-RN for formulate a water-based drilling mud, noting the influence of varying the concentration of calcium and magnesium into filtered and rheology tests. We conducted a simple 32 factorial experimental design for statistical modeling of data. The results showed that the varying concentrations of calcium and magnesium did not influence the rheology of the fluid, where in the plastic viscosity, apparent viscosity and the initial and final gels does not varied significantly. For the filtrate tests, calcium concentration in a linear fashion influenced chloride concentration, where when we have a higher concentration of calcium we have a higher the concentration of chloride in the filtrate. For the Urucu’s produced water based fluids, volume of filtrate was observed that the calcium concentration influences quadratically, this means that high calcium concentrations interfere with the power of the inhibitors used in the formulation of the filtered fluid. For Riacho’s produced water based fluid, Calcium’s influences is linear for volume of filtrate. The magnesium concentration was significant only for chloride concentration in a quadratic way just for Urucu’s produced water based fluids. The mud with maximum concentration of magnesium (9,411g/L), but minimal concentration of calcium (0,733g/L) showed good results. Therefore, a maximum water produced by magnesium concentration of 9,411g/L and the maximum calcium concentration of 0,733g/L can be used for formulating water-based drilling fluids, providing appropriate properties for this kind of fluid.

Avaliação do impacto socioambiental de indústrias têxteis no rio Jundiaí - Macaíba/RN/Brasil

The contamination of aquatic environments is a phenomenon that dates back the origins of human civilizations and was amplified by the advent of industrial processes. The Jundiaí river , Macaíba's main water source, suffering discharge of effluents from various industries. The study work´s in two fronts, the environmental perception front was conducted through semistructured interviews whose textile effluent was appointed by the population as the main problem in the river. It was observed that nearly all respondents had concerns about the environment. In addition, there is an inclusion of individuals as the cause of the problem, because a significant part recognizes that its activities may cause damage to the environment and people's health. In other front, the experimental monitoring of water quality was conducted through ecotoxicological tests and physiochemical analysis that proposed to assess Pomacea lineata .Mysidopsis juniae isolated effect of textile effluent and its influence on the river compared with the limits established by Brazilian law. Although the physio-chemical analysis shows is inconclusive about the participation of the textile effluent in environmental contamination of the river, the ecotoxicological tests have shown to blunt the signal that the effluent may present a risk to aquatic organisms and consequently to human health. Thus, an interdisciplinary way it was possible to study the cause of the environmental problem identified by the population in the realization phase and measurable effect on water quality analysis in the river by means of the tests mentioned.

Tratamento de cascalho de perfuração utilizando sistemas microemulsionados

The oil industry is one of the activities that generates more waste to the environment. The drill cuttings is a waste generated in large quantities in the drilling process and that may cause environmental damage such as soil contamination and consequently the contamination of groundwater if disposed of without prior treatment. Arises the need to develop scientific activities and research ways to adapt these wastes the current environmental standards. In the case of solid wastes, the NBR 10004: 2004 of the Brazilian Association of Technical Standards (ABNT) classifies them into class I waste (hazardous) and class II (not dangerous), which determines which wastes may or may not be discarded in the environment without causing environmental impact. This study presents a novel alternative for treating drill cuttings, where this waste was classified as class I (Abreu & Souza, 2005), mainly by removing the n-paraffin present in it, since this arises when using drilling fluids base oil. Using microemulsion systems promotes the removal of this contaminant drill cuttings samples from wells located in Alto do Rodrigues - RN. Initially, we determined the concentration of paraffin using infrared method in samples were extracted with ultrasound, we obtained a paraffin concentration in the range from 36.59 to 43.52 g of paraffin per kilogram of cuttings. Used two microemulsion systems containing two nonionic surfactants from different classes, one is an alcohol ethoxylated (UNTL-90) and the other an nonylphenol ethoxylated (RNX 110). The results indicated that the system UNTL-90 surfactant has better efficiency than the system with RNX 110. The study of the influence of contact time at the extraction showed that for times greater than 25 minutes has a tendency to increase the percentage extraction with increasing contact time. It was also observed that the extraction is fast because at 1 minute contact has 22.7% extraction. The reuse of the microemulsion system without removing the paraffin extracted in previous steps, showed reduction of 29.32 in percentage of extraction by comparing the first and third extraction, but by comparing the first and second extractions reduction is 8.5 in percentage extraction, so the systems reuse optimization can be an option for economically viable removing paraffin from cuttings. The extraction with shaking is more effective in the treatment of cuttings, reaching the extraction percentage of 87.04%, that is, obtaining a drill cuttings with 0.551% paraffin. Using the percentage of paraffin employed in non-aqueous drilling fluids and fluid maximum limit on cuttings for disposal established by the Environmental Protection Agency of the United States (US EPA), one arrives at the conclusion that the level of paraffin on gravel cannot exceed 3.93%. Conclude that the amount of paraffin in the treated cuttings with the microemulsion system with shaking is below the established by US EPA, showing that the system used was efficient in removing the paraffin from the drill cuttings.

Avaliação da biodegradação do dibenzotiofeno utilizando lodos ativados

During the oil refining process a huge discard volume of water occurs, which carries the contaminants from the process. A class of contaminant compounds resulting from the petrochemical industry are the Polyaromatic Hydrocarbons (PAH's). To evaluate the biodegradation of Dibenzothiophene in refinery water a synthetic wastewater was prepared to be treated using activated sludge. For this, a 2 3 Composite Design (plus 3 central points and six axial points) was carried out. The planning had as independent variables (factors) the initial concentration of DBT, pH and time of biodegradation. Biodegradation of DBT was assayed following the parameters COD, pH, temperature, SS, VSS, FVS, SVI. Concerned to the chromatographic conditions, a methodology was validated in order to verify the presence of DBT and its metabolite, 2-HBF, in the final wastewater treated by activated sludge system using a liquid - liquid extraction coupled to HPLC / UV analysis. The parameters used for validation were DL, QL, linearity, recovery and repeatability. As for optimization, the results indicated that the studied methodology can be used in monitoring the DBT degradation and 2- HBF by activated sludge, as they showed excellent linearity values, coefficients of variation, so as satisfactory recovery percentage. COD reduction efficiency tests showed an average percentage of 64.4%. The increasing trend for the results for the TSS and VSS tests showed that the activated sludge was well tailored. The best operating conditions for the reduction of COD were observed when operated with median concentrations of DBT, a higher time to biodegradation, and pH in both the acidic range as the basic one. The biodegradability of the DBT was confirmed by determining the presence of HBF-2. The highest concentrations of HBF-2 were obtained in extreme concentrations of DBT and pH, and higher biodegradation times.

Fluxo de fluído através de um meio poroso fractal desordenado. Análise das tensões de cisalhamento e efeito de escala na estimativa das forças viscosas

In this work we have investigated some aspects of the two-dimensional flow of a viscous Newtonian fluid through a disordered porous medium modeled by a random fractal system similar to the Sierpinski carpet. This fractal is formed by obstacles of various sizes, whose distribution function follows a power law. They are randomly disposed in a rectangular channel. The velocity field and other details of fluid dynamics are obtained by solving numerically of the Navier-Stokes and continuity equations at the pore level, where occurs actually the flow of fluids in porous media. The results of numerical simulations allowed us to analyze the distribution of shear stresses developed in the solid-fluid interfaces, and find algebraic relations between the viscous forces or of friction with the geometric parameters of the model, including its fractal dimension. Based on the numerical results, we proposed scaling relations involving the relevant parameters of the phenomenon, allowing quantifying the fractions of these forces with respect to size classes of obstacles. Finally, it was also possible to make inferences about the fluctuations in the form of the distribution of viscous stresses developed on the surface of obstacles.