1000 resultados para taxas de oxidação


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O objeto da presente patente é um reator fotoeletrocatalítico operando com eletrodos nanoporosos ou nanotubulares de Ti/TiO~ 2~ como fotoanodos, uma rede de platina como cátodo para oxidação fotoeletrocatalítica de efluentes coloridos, sob densidade de corrente constante e irradiação de luz UV, utilizado no tratamento de águas de rejeito contendo corantes ácidos, básicos, dispersos, reativos e agentes dispersantes e efluentes coletados de indústrias têxteis. Ambos os eletrodos mostraram uma performance acima dos métodos usuais removendo não apenas a coloração, mas processando grande mineralização dos diversos tipos de corantes, surfactantes etc. em efluentes da industria têxtil.

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Pós-graduação em Ciência e Tecnologia de Materiais - FC

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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This paper addresses the context of emissions of Greenhouse Gases (GHG) from activities related to Coal, called fugitive emissions. The survey of factors, development, analysis, and suggestions for controlling emissions are conducted in order to reduce risks to the environment and people around it. The greenhouse gases absorb radiation, emitted by the Earth’s surface, and hinder their escape into space. This process is essential to terrestrial life. Increasing the concentration of those gases in the atmosphere has led to an increase in the terrestrial temperature. A selection of processes that emit gases and the study and development of calculations for measuring fugitive emissions applied in different sources from coal are performed. The greenhouse gases can be released from the extraction, processing, storage, and transportation of fossil fuels to the end consumer. Coal has 4 main fugitive factors: mining, post-mining, oxidation at low temperature, and uncontrolled combustion. The coal formation process produces methane (CH4) and carbon dioxide (CO2), being the methane, the main greenhouse gas from the coal mining and handling. The types of activities and the weight of each in the issuing process are observed. It is also made comparisons between the countries with the highest emissions rates. Are evaluated what has been done and what is needed to decrease emissions, for example the use of gas as an alternative fuel for energy generation

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The development of human societies and their activities generate many impacts on the environment and natural resources. The consequence of these problems is a disturbance of the systemic dynamics of Planet Earth. Study these impacts are a way to understand the workings of this system and undertake efforts to prevent minimize and anticipate scenarios caused by environmental impacts. In this sense, from a systemic approach seeks to understand the way how is the interaction of the components of the ecosystems, adopting for this task the hydrographic basin as a natural unit of planning and management in view of the fact all landscape elements (atmosphere, hydrosphere, biosphere and geosphere) interact so that the reflections of human activities can be represented in this unit. Thus, this study aims to quantify chemical erosion rates in the hydrographic basin of Ribeirao Monjolo Grande, Ipeúna (SP), which is relevant to analyze the geomorphological characteristics of the area, which may serve to better exploitation of natural resources

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The present work assessment materials can be used as fuel cells electrocatalysts. The alkaline fuel cell though was less studied, has some advantages compared to the acid configuration. The materials assesment were Au polycrystalline and intermetallics ordered phases of AuIn, AuSn and AuSb2. Your electrocatalytic properties were studied across cyclic voltametry and chronoamperometry techniques in Sodium Hydroxide 0,15M and Metanol 0,15M solution. The results obtained show a more efficiency to intermetallic AuIn as electrocatalyst for the oxidation reaction of methanol in alkaline medium, it showed high levels of current density and on set potential less positive compared to Au polycrystalline. The intermetallic AuSn showed activity just higher concentrations of methanol. Except AuSb2, who represented himself unstable in alkaline media, the intermetallics AuIn and AuSn present a promising future as anode materials for the oxidation in alkaline medium

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Currently with the growing technological advancement and global, new areas are being devastated, and as a result, the erosion became more frequent causing loss of soil, infiltration capacity of the surface and weathering of rocks. In this way, environmental studies are increasingly frequent to understand the environment in which we live, but also to avoid any degradation of the same and of finite natural resources, which are essential for human life. From this, this work has as main goal, analyzing the rates of chemical and mechanical erosive watershed of Ribeirão Jacutinga, at its mouth, in the city of Rio Claro, supporting environmental studies and sustainable development today. Order to reach these values were measured and total dissolved solids in suspension in the stream during the months from January to July 2012. As results included higher rates of both physical and chemical weathering in the rainy months, especially january

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Melatonin is an endoleamine that has anti-inflammatory, immunomodulating and antioxidants properties. But there is a contradiction between the antioxidant effects of melatonin and glutathione (GSH). Therefore, the main objective of this work was to study the effect of melatonin on the oxidation of GSH and the effect of GSH on the oxidation of melatonin by peroxyl radicals generated by thermolysis of 2,2 -Azobis(2- amino-propane)-dihydrochloride (AAPH). The influence of the reaction conditions and the identity of the products of oxidation were also studied. The main products obtained during the oxidation of melatonin were its monohydroxylated derivative and N1-acetyl- N2-formyl-5-methoxykynuramine (AFMK), which is the product obtained by oxidative cleavage of the melatonin indole ring. By studying the buffer type, pH and the presence or absence of dissolved oxygen in the reaction system, it was observed that, the yield of AFMK was higher when the pH or the concentration of oxygen was increased. Comparing the reactivity of both molecules GSH and melatonin, it can be seen that intermediates radicals generated during the oxidation of melatonin are able to oxidize GSH itself. We propose that this chemical property could justify the recent reports that demonstrated the inability of melatonin to inhibit the oxidation of GSH in cells

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Aiming to reduce the cost of electrocatalysts and a greater resistance to CO poisoning this work was to study the adsorption and oxidation of carbon monoxide on ordered intermetallic phases AuIn, AuSb2, AuSn, PdSb and PdSn using voltammetric techniques in alkaline electrolyte solution. The results suggest that the AuSn and PdSn intermetallics has some form of resistance to CO poisoning. It is assumed that this behavior is a result of electronic effect and the effect of the third body has been achieved by adding a second metal to Au and Pd. However, further studies should be conducted to confirm this hypothesis as to test these materials as electrocatalysts in the reaction of oxidation of fuels

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The success in implementing an embryo transfer program derives from many factors. The embryo recovery rate is one of the most important factors, and allows the transfer to the recipient mare. This rate comes from a group of elements such as donor´s characteristics, collection date, reproductive management, semen quality, technician skill. Mainly because of the great importance of this direct interference on the results of an embryo recovery program, this study aimed to review the factors involved in embryo recovery rates in donor mares during an embryo transfer, suggesting some ways of improving these results

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This work has main aim of is to propose the synthesis and characterization of nanostructured materials for oxidation of carbohydrates such as glucose, with non-enzymatic catalysis. The proposed pathway of synthesis of metal catalysts is the polyol method and techniques of physical characterization proposals for analysis of prepared catalyst pass through diffraction technique of ray-x (DRX), scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy ray-x (EDX). Technical proposals for the electrochemical characterization of the synthesized catalysts are Cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The prospects of this work are compared by the catalytic activity of the sensor designed with non-enzymatic sensors and biosensors also known in the literature

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Pós-graduação em Química - IQ