974 resultados para Sílica ativa : Materiais
Resumo:
The need to preserve the environment has led to the search for new materials for efficient disposal of chemical compounds that alter the stability of our natural resources. Among these resources, stands in first place the water, as a precious commodity and scarce, leading to the proper use and reuse. As a result, the World Health Organization has established maximum permissible values in drinking water, such as: 50 mg/L, 0, 1 mg/L and 0, 5 mg/L to at-3, at-2, NH 4, respectively. For these reasons, assesses the implementation of new materials and water treatment processes aiming at the removal of these compounds, such as alumina, in the form of powder or as a support for a catalytic system using inorganic membranes capable of supporting more severe conditions of temperature and pressure by opening new possibilities for applications of membrane reactors; and also for electrochemical treatments with doped diamond bobo electrodes (BDD) as anode and copper as cathode. For such purpose, was conducted the study of adsorption of nitrate in different times to assess the time required to achieve equilibrium by employing three commercial alumina called: acidic, basic and neutral alumina, with subsequent treatment only in the acidic alumina impregnating metals (PdCu/Al2O3) for the catalytic reaction. The materials were previously characterized by XRD, SEM techniques and ABET. Aluminas presented a considerable adsortive capacity of nitrate in the first thirty minutes, equivalent to 50% of removal reaching equilibrium in that time. After treatment, using alumina as catalyst for the reaction in batch reactor (Pd-Cu/Al2O3), the results were more favourable, totalling 64% reduction of ion NO3-at the end of three hours. On the other hand, the results for the catalytic reaction using the catalytic support Pd-Cu/TiO2 in membrane reactor proved to be low. -if, in this way, improve the conditions of catalytic system to optimize the process. Already, for the electrochemical tests using DDB1 electrodes as anode, and Cu, as cathode, there was a fairly significant nitrate reduction, approximately 80% of ion removal during three hours and cost viable applications.
Resumo:
Increasing energy demand is being met largely by fossil fuel reserves, which emit CO2, SOx gases and various other pollutants. So does the search for fuels that emit fewer pollutants and have the same energy efficiency. In this context, hydrogen (H2) has been increasingly recognized as a potential carrier of energy for the near future. This is because the H2 can be obtained by different routes and has a wide application area , in addition to having clean burning, generating only H2O as a product of combustion , and higher energy density per unit mass . The Chemical Looping Reforming process (CLR) has been extensively investigated in recent years, it is possible to regenerate the catalyst by applying cycles of reduction and oxidation. This work has as main objective to develop catalysts based on nickel and cobalt to study the reactivity of reform with chemical recycling process. The catalysts were prepared by three different methods: combustion assisted by microwave, wet impregnation and co-precipitation. All catalysts synthesized have the same amount by weight of the active phases (60% w / w). The other 40 % m/m consists in La2O3 (8% w / w), Al2O3 (30% w / w) and MgO (2%). Oxygen carriers have been named as follows: N or C, nickel or cobalt, followed by the number 3 or 6, meaning 30 to 60% of active phase in the oxide form and C, CI or CP, which means self-combustion assisted by microwave, self-combustion assisted by microwave followed by wet impregnation and co-precipitation. The oxygen carriers were then characterized by the techniques of X-ray diffraction (XRD), surface area (BET), temperature programmed reduction (TPR) and scanning electron microscopy (SEM). The characterization results showed that the different synthesis methods have led to obtaining different morphologies and structures. Redox tests using CH4 as reducing agent and sintetic air as oxidant agent was done with N6C and C6C, N6CI and C6CI and N6CP and C6CP oxygen carriers. The tests revealed different behaviors, depending on active phase and on synthesis procedure. N6C oxygen carrier produced high levels of H2. The C6CI oxygen carrier produced CO2 and H2O without carbon deposits.
Resumo:
Atualmente com o crescente aumento de dispositivos robóticos destinados para aplicação na área de mobilidade de pessoas que sofreram algum tipo de lesão medular, se faz necessário desenvolver novas ferramentas para tornar tais equipamentos mais adaptáveis, seguros e autônomos. Para que as órteses robóticas que auxiliam na locomoção de pessoas paraplégicas possam desempenhar sua função, estas devem ser capazes de reproduzir os movimentos perdidos com o máximo de fidelidade e segurança em ambientes que eventualmente possam conter obstáculos de diferentes tipos como buracos, escadas e calçadas. As órteses robóticas para membros inferiores têm a capacidade de caminhar, subir e descer degraus, todavia, esses movimentos, na maioria das vezes, não se adaptam ao ambiente, sendo assim, para uma órtese robótica que foi projetada para subir um degrau com uma determinada altura ao se deparar com um degrau maior provavelmente não conseguirá realizar essa tarefa com a mesma segurança. Para solucionar esse e outros problemas, esse trabalho apresenta um Sistema de Auxílio à Locomoção (SAL) dotado de um planejador de passos e um gerador de referências angulares com características antropomórficas para a órtese robótica Ortholeg. O SAL utiliza dados antropométricos do usuário para gerar um padrão de marcha personalizado, dessa forma, a órtese em questão é capaz de adaptar o tamanho do passo para não colidir com obstáculos presentes no ambiente e transpor buracos com diversos tamanhos, subir e descer escadas e calçadas com diferentes valores de altura e comprimento. Para desenvolver o sistema de auxílio à locomoção foram adaptadas técnicas de planejamento de caminho, usadas a princípio em robôs bípedes. São apresentados vários experimentos que mostram a órtese Ortholeg realizando alguns movimentos com características antropomórficas para diferentes distâncias de caminhada e três tipos de obstáculos: degrau, buraco e calçada. A autonomia adquirida com a utilização do sistema de planejamento apresentado facilita a utilização de órteses robóticas como também garante uma maior segurança ao usuário.
Resumo:
The integrated management of municipal solid waste in Brazil is held legally responsible by the city council administration. This is done since the year 2010 with the publication of the National Solid Waste Policy term. According to the policy and law, each city must encourage the implementation of selective collection and the participation of waste picker´s entities aiming social inclusion. However, these actions haven’t yet reached its legal aims. These workers are considered regarding collection actions but are stripped of certain basic labor rights not in conformation with the Decent Work concept. This type of work, according to International Labour Organization, must be seen as work that is properly paid for and must be done regarding conditions of freedom, equity, security and able to provide workers with a dignified life conditions. Thus, this work aims to investigate the implementation process regarding the Solid Waste National Policy in Natal-Rio Grande do Norte in Brazil. This is done considering socio-productive insertion of recyclable material collectors. The research is substantiated by a qualitative approach as well as documental and bibliographical research. A field research considering the cooperatives as well “in locco" observation and semi-structured interviews were carried out between the time span of 2013 and 2014. In order to investigate decent daily working conditions the research emphasized municipal management actions in Natal towards social inclusion that aim to reflect on the progress and difficulties experimented. It is seen that even when these cooperatives receive government support there are still important struggles that need to be overcome. The worker´s tasks are risky, the work environment in not safe or is adequate in terms of health issues. There is the stigma of it being considered an occupational task, the low individual income distancing the activity regarding parameters of the Green Employment and Decent Work concept. On the other hand, the survey showed potential as the relentless pursuit on behalf of the cooperatives that still search better work condition improvement.
Resumo:
This work presents a new ceramic material obtained through the incorporation of solid waste from the steel industry and known as dedusting powder PAE - in ceramic formulations based on clay, potassium and sodium feldspars, kaolin and talc. Formulations were prepared with ceramic residue levels of 0% (basic mass - MB), 2%, 4% and 8%, subjected to firing at temperatures of 1000 ° C, 1050ºC, 1100ºC and 1150ºC for periods of 15 min. and 120 min. The physicchemical and mechanical properties of these ceramic formulations were determined based on the firing temperature, residence time in the oven and the percentage of waste. Since the physicochemical and mechanical properties of the sintered materials were evaluated by chemical analysis techniques (fluorescence X-rays - FRX), particle size distribution, specific surface area, apparent density, structural analysis by diffraction of X-rays (DRX) and characterization of surface by scanning electron microscopy (SEM). The magnetic response characteristics and the pattern of magnetic ferrites of the samples were analyzed in the assay conditions, having noticed that the saturation magnetic susceptibility depend on the sintering temperature of the material and it is associated with its crystal structure. From the analysis results, it was concluded that the ceramic material with better physical and mechanical properties is obtained when the 8% from PAE residue is added to standard formulation under the burn time of 15 minutes and temperature of 1150ºC.
Resumo:
Surface defects on steel parts borne costs of smelting industries due to the need of rework. Sand molds are frequently used in foundry industries and largely responsible for providing surface defects. This study aims to optimize the levels of the molding process variables to minimize the occurrence of surface defects in steel castings in silica sand molds chemically linked by cold cure process. The methodology used the experimental design with split plot, being considered in the study the resin percentage factors in the mold formulation, addition of iron oxide, type of paint, the paint application method, amount of ink layers, use of hot air along the lines and waiting time of the mold before casting. They were analyzed as response variables erosion defects, sand inclusion, penetration, porosity and surface finish. Tensile strength tests were performed to evaluate the influence of factors on mechanical parameters and the microstructural parameters were carried out the analysis of X-ray diffraction, scanning electron microscopy (SEM) and thermal analysis (TG / DSC / dilatometry). The results elucidate that for the faulty erosion, the only significant factor with a 95% confidence level was the type of ink and the ink alumina-based superior results obtained. For the sand inclusion of defect, there were three significant factors, with best results obtained with alumina-based paint and spray applied using hot air in the mold before casting the metal. For the defect penetration, there were four significant factors, the best results being achieved with 0.8% of resin and addition of iron oxide in the molding formulation, the paint being applied by brush and standby time of 24 hours before leak. For the defect porosity with a 95% confidence level, no significant factors. For the defect surface finish, the best results were achieved with the 0.8% formulation of the resin in the mold and application of the paint brush. To obtain the levels of the factors that optimize all defects simultaneously, we performed a weighted average of the results of each type of fault, concluding that the best levels of the factors were: 0.8% resin and addition of iron oxide in the formulation of the template, application of two coats of paint applied with a brush or spray, using hot air in the mold before casting and 24 hours of waiting ready the mold before casting. These levels of the optimized factors were used in an experiment to confirm that ratified the results, helping to reduce rework and consequently reducing costs of cast steel parts.
Resumo:
O presente estudo aborda a utilização de carvão ativado comercial na remoção de ácidos húmicos em meio aquoso. O objetivo principal é desenvolver e caracterizar materiais carbonáceos visando aplicações de remoção de ácidos húmicos em meio aquoso por processos de adsorção e oxidação. Testes de remoção do poluente foram desenvolvidos com a utilização do carvão comercial, carvão modificado a partir de tratamentos ácidos e compósito confeccionado com a impregnação de ferro no carvão. Espumas de carbono com dispersões de carvão ativado e óxidos de ferro também foram desenvolvidas buscando aplicações de remoção do poluente através de processos eletroquímicos. Os resultados das caracterizações demonstraram ganho de área superficial a partir do tratamento ácido, a presença dispersa de ferro em todo carvão na forma de fase maghemita com a introdução do metal, e ganho de estabilidade eletroquímica na espuma, com a presença de dispersões de carvão ativados impregnados com ferro. O processo oxidativo Fenton, foto assistido por radiação UV, demonstrou maior eficiência para remoção do ácido húmico em água.
Resumo:
Bionanocomposites systems clay base (montmorillonite and sepiolite), layered double hidroxides and biopolymers (carboxymethylcellulose and zein) were evaluated as topical delivery systems with antibacterial activity and as oral delivery systems. For this study, neomycin, a topical antibiotic, indicated mainly for open wound infections. The drug amoxicillin, an antibiotic indicated mainly for throat infections, were also used in this study. Both antibiotics were used as model drugs. Initially, drugs were incorporated directly into the biopolymer matrix, comprising the combination of carboxymethylcellulos and zein, being conformed as movies and balls and evaluated for their antibacterial activity and controlled release simulating gastrointestinal fluids. Moreover, hybrids materials have been prepared where the neomycin drug was incorporated into the lamellar inorganic solids, such as montmorillonite by ion exchange reaction, and the fibrous type, such as sepiolite by adsorption in aqueous solution. But the drug amoxicillin was incorporated into layered double hydroxides by anion exchange and montmorillonite by cation exchange. The resulting hybrids were in turn combined with the biopolymer matrix yielding bionanocomposites shaped materials such as films were tested for their antibacterial activity, and the shaped materials beads were tested for their release in the gastrointestinal fluids. Through the analysis of various physico-chemical techniques, we observed the interactions between the studied materials, the formation of hybrids materials, obtaining the bionanocomposites materials and material efficiency when applied in controlled release of drugs both topical and use oral mainly influenced by the presence of zein, are promising as topical delivery systems and oral drugs.
Resumo:
Brazil is a country in development, rich in natural resources. In order to grow sustainably, it is necessary to Brazil to preserve its environment, which is an expressive challenge, especially to industries, such as those producing ceramic materials. This study was developed using Porcelain Tile Polishing Residue (RPP) in blends with soil to build compacted fills. This residue is a slurry generated during the polishing process of porcelain tiles and contains powdery material from the polished tile, the abrasives used during the process and cooling water. The RPP was collected from a private company located in Conde/PB and it was mixed with a sandy-clayey soil, to build the fills. Laboratorial tests were conducted with pure soil, pure RPP and blends in proportions of 5%, 10%, 15% and 20% of RPP in addition to the dry mass of pure soil. The Chemical and Physical Characterization tests performed were: specific solid weight, grain size distribution, laser analysis of grain size distribution, Atterberg limits, X ray fluorescence, X ray diffraction, scanning electron microscopy and soil compaction,. The materials and blends were also compacted and direct shear tests and plate load tests were performed. Plate load tests were conducted using a circular plate with 30 cm diameter, on specimens of pure soil and 5% blend, compacted in a metallic box inside the Soil Mechanics Laboratory of the Federal University of Rio Grande do Norte, Brazil. Both mechanical tests performed were conducted under inundated conditions, willing to reduce the influence of soil suction. An evaluation of the results of the tests performed shows that RPP is a fine material, with grain size distribution smaller than 0,015mm, composed mainly of silica and alumina, and particles in angular shape. The soil was characterized as a clayey sand, geologically known as a lateritic soil, with high percentages of alumina and iron oxide, and particles with rounded shape. Both the Soil and the blends presented low plasticity, while the residue showed a medium plasticity. Direct shear tests showed that the addition of RPP did not cause major changes into blends’ friction angle data, however, it was possible to note that, for the proportions studied, that is a tendency of obtain lower shear stresses for higher percentages of RPP in the blends. Both pure soil and 5% mixture showed a punching disruption for the Plate load test. For this same test, the allowable stress for 5% mixture was 44% higher than the pure soil, and smaller vertical settlement results for all stresses.
Resumo:
Brazil is a country in development, rich in natural resources. In order to grow sustainably, it is necessary to Brazil to preserve its environment, which is an expressive challenge, especially to industries, such as those producing ceramic materials. This study was developed using Porcelain Tile Polishing Residue (RPP) in blends with soil to build compacted fills. This residue is a slurry generated during the polishing process of porcelain tiles and contains powdery material from the polished tile, the abrasives used during the process and cooling water. The RPP was collected from a private company located in Conde/PB and it was mixed with a sandy-clayey soil, to build the fills. Laboratorial tests were conducted with pure soil, pure RPP and blends in proportions of 5%, 10%, 15% and 20% of RPP in addition to the dry mass of pure soil. The Chemical and Physical Characterization tests performed were: specific solid weight, grain size distribution, laser analysis of grain size distribution, Atterberg limits, X ray fluorescence, X ray diffraction, scanning electron microscopy and soil compaction,. The materials and blends were also compacted and direct shear tests and plate load tests were performed. Plate load tests were conducted using a circular plate with 30 cm diameter, on specimens of pure soil and 5% blend, compacted in a metallic box inside the Soil Mechanics Laboratory of the Federal University of Rio Grande do Norte, Brazil. Both mechanical tests performed were conducted under inundated conditions, willing to reduce the influence of soil suction. An evaluation of the results of the tests performed shows that RPP is a fine material, with grain size distribution smaller than 0,015mm, composed mainly of silica and alumina, and particles in angular shape. The soil was characterized as a clayey sand, geologically known as a lateritic soil, with high percentages of alumina and iron oxide, and particles with rounded shape. Both the Soil and the blends presented low plasticity, while the residue showed a medium plasticity. Direct shear tests showed that the addition of RPP did not cause major changes into blends’ friction angle data, however, it was possible to note that, for the proportions studied, that is a tendency of obtain lower shear stresses for higher percentages of RPP in the blends. Both pure soil and 5% mixture showed a punching disruption for the Plate load test. For this same test, the allowable stress for 5% mixture was 44% higher than the pure soil, and smaller vertical settlement results for all stresses.
Resumo:
O desperdício alimentar constitui um problema à escala mundial. Em Portugal, no contexto de crise económica que vivemos importa combater a situação de desigualdade no acesso e no consumo de alimentos, o que implica sensibilizar a população para uma mudança de comportamentos. Neste sentido, para a promoção do combate ao desperdício alimentar e de uma cidadania mais ativa em matéria de sustentabilidade é fundamental recorrer a diversas estratégias, nomeadamente a nível educacional. Todavia, para que este processo de sensibilização produza os efeitos desejados é necessário chegar primeiro aos professores trabalhando com eles valores e saberes relativos à temática do desperdício alimentar. Neste contexto surge o projeto “Sensibilizar para o Desperdício Alimentar” desenvolvido pela Escola Superior de Educação de Santarém e que envolveu a conceção e implementação de uma ação de formação dirigida a professores do 1.º e do 2.º Ciclo do Ensino Básico. A apreciação que os professores fizeram da formação foi muito positiva, nomeadamente da pertinência das temáticas abordadas, da qualidade dos materiais e da metodologia adotada. A estas evidências soma-se o interesse demonstrado por outras instituições de ensino superior, que pretendem implementar, em breve, esta oficina de formação, o que nos incentiva a dar continuidade ao projeto.
Resumo:
In this work are considered two bidimensional systems, with distints chacacteristcs and applicabilitys. Is studied the adsorption of transition metals (MT) Fe, Co, Mn and Ru in extended defects, formed by graphene grain boundaries. First in pristine graphene The hollow site of carbon hexagon, in pristine graphene, are the most stable for MT adsorption. The Dirac cone in eletronic structure of graphene was manteined with the presence of MT. For the considered grain boundaries the MT has a greater stability for absorption in the grain boundaries sites in comparison with pristine graphene. Through the energy barrier values, are observed diffusion chanels for MT localized on the grain boundaries. This diffusion chanels indicate a possible formation of nanolines of MT in graphene. For the first stage of the nanolines, ate observed a better stability for the system with greater MT concentration, due to MT-MT interactions. Also, due to the magnetic moment of the MT, the nanolines show a magnetization. For the most stable configurations the system are metallics, particularly for Fe the band structure indicates an anisotropic spin current. In a second study, are considereted the retention capacity for metallic contaminants Cd and Hg in clayminerals, kaolinite (KAO) and montmorillonite (MMT). Through the adsorption energies of contaminantes in the clayminerals, was observed a increase in stability with the increase of contaminants concentration, due to the interaction Cd-Cd and Hg-Hg. Also, was observed that KAO has a strong interaction beteween monolayers than MMT. In this sence, for the adsoption process of contaminantes in the natural form of KAO and MMT, the latter has a better retention capacity, due to the small net work for contaminant intercalation. However, when the modification of clayminerals, with molecules that increase the spacing between monolayers, exist a optimal condition, which the contaminant absorption are more stable in KAO system than in MMT. In the Langmuir adsorption model for the clayminerals in the optimal monolayer spacing, the retention capacity for Cd and Hg in KAO system are 21% greater than in MMT system. Also, for the X-ray Absorption Near Edge Spectroscopy (XANES) for the K edge of Cd and Hg, are found a positive shift of absorption edge with the decreasing of monolayer spacing. This result indicates a possible way to determine the concentration of adsorbed contaminats in relation to unabsorbed ones, from the decomposition of experimental XANES in the obteined spectras.
Resumo:
Este trabalho realizado, inicialmente, com base na análise de alguns documentos referentes à legislação educacional brasileira vigente tem por objetivo desenvolver uma investigação acerca da aplicabilidade da Assistência Estudantil dentro do Instituto Federal de Educação, Ciência e Tecnologia de São Paulo (IFSP). A partir da questão do Direito à Educação de todo cidadão, que está garantido em nossa Constituição Federal, o governo elaborou, no ano de 2010, o Programa Nacional de Assistência Estudantil (PNAES). Respaldados nesse Programa, o IFSP criou, em 2011, o Programa de Assistência Estudantil (PAE), dando validade e continuidade às ações desenvolvidas nos Campi para minimizar a evasão e o fracasso escolar, com vistas a garantir a permanência dos educandos no referido Instituto. Embora o PAE tenha sido implementado em todos os Campi do IFSP, no decorrer do presente trabalho analisamos e estudamos, exclusivamente, o Campus Cubatão, localizado na região da Baixada Santista devido a, dentre outros fatores, ter sido a primeira unidade descentralizada dos Institutos Federais do país. Assim, neste estudo, temos como objetivo analisar a estrutura de funcionamento do IFSP com o intuito específico de investigar o Campus de Cubatão, verificar as questões de Vulnerabilidade Social encontradas na destacada instituição, averiguar as ações do PAE que nascem do PNAES, observar a aplicabilidade desse programa com base no princípio da Gratuidade Ativa e do Direito à Educação de todo cidadão. Para tanto, utilizamos, fundamentalmente, além da legislação já mencionada, o princípio da Gratuidade Ativa de Melchior (2011) e o conceito de Vulnerabilidade Social proposto por Alves (1994) e por Abramovay (2002).