Made available in DSpace on 2014-12-17T15:42:21Z (GMT). No. of bitstreams: 1 JoseCVM_TESE_capa_ate_pag128.pdf: 3265790 bytes, checksum: 756c257ab1c64e4914df34565709a45f (MD5) Previous issue date: 2013-07-31 / 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 / Neste trabalho foram sintetizados os materiais denominados fosfato de vanadila, hidrogeno fosfato de vanadila e fosfatos de vanadila dopados por metais de transi??o com fins na adsor??o de am?nia, sulfeto de hidrog?nio e ?xido de nitrog?nio. Para a caracteriza??o dos compostos de partida, recorre-se ?s t?cnicas de DRX, FTIR, FRX e TG. Ap?s a caracteriza??o dos substratos, procedeu-se a adsor??o dos gases NH3 e H2S em reator, passando os gases a vaz?o cont?nua durante 30 min e temperatura ambiente. Dados gravim?tricos indicam que as matrizes de maior desempenho na adsor??o de am?nia foram ?quelas dopadas por alum?nio e mangan?s, obtendo resultado de 216,77 mgNH3/g e 200,40 mgNH3/g de matriz, respectivamente. A matriz de maior desempenho para a adsor??o de sulfeto de hidrog?nio foi ?quela dopada por mangan?s, obtendo resultado de 86,94 mgH2S/g de matriz. As s?nteses dos substratos VOPO4.2H2O e MnVOPO4.2H2O com o g?s ?xido de nitrog?nio foram realizadas em solu??o, objetivando-se os produtos finais VOPO4.G.nH2O e MnVOPO4.G.nH2O (G = NO e n = n?mero de mol?culas de ?gua). O comportamento termoanal?tico e a espectroscopia na regi?o do infravermelho s?o indicativos da forma??o do composto VOPO4.2,5NO.3H2O. Resultados de microscopia eletr?nica de varredura (MEV) e espectroscopia de energia dispersiva (EDS) dos materiais fosfatos de vanadila e fosfatos de vanadila dopados ap?s rea??o no estado s?lido ou em solu??o com os gases indicam mudan?a na morfologia dos substratos, al?m da forma??o de cristais de enxofre ortorr?mbico sobre seus respectivos hospedeiros quando estes adsorvem sulfeto de hidrog?nio

In ariden Gebieten tritt Schwefelwasserstoff häufig im Grundwasser auf, wodurch dessen Nutzung für die Trinkwassergewinnung aufgrund des störenden Geruchs und Geschmacks stark beeinträchtigt wird. Die in der Praxis oft eingesetzte Belüftung erweist sich zumeist als ineffizient und führt zu Geruchsbelästigungen in der Umgebungsluft. Das Ziel der Arbeit, die im Rahmen eines deutsch-israelischen Forschungsprojekts angefertigt wurde, bestand darin, einen wirksamen und für den praktischen Einsatz bei der Wasseraufbereitung geeigneten Katalysator zur Entfernung von Schwefelwasserstoff zu entwickeln, hinsichtlich verschiedener Verfahrensparameter und relevanter Randbedingungen durch systematische Batch- und Säulenversuche zu erproben und zu optimieren. Wichtige Kriterien zur Charakterisierung der Katalysatoren waren die Kinetik des Sulfidumsatzes, die Langzeitstabilität und die Zusammensetzung der Reaktionsprodukte. Die Nachahmung natürlich vorkommender Strukturen (z. B. Häm-Gruppe) und deren Anpassung an eine katalytische Sulfidoxidation war der Grundgedanke am Anfang der Arbeit. Entsprechende Materialien, organische Metallkomplexe (Porphyrine) auf Kohlenstoffträgern (Acetylen Black), wurden bereits erfolgreich bei der Sauerstoffreduktion in Brennstoffzellen eingesetzt. Cobalttetraphenylporphyrin (CoTPP) zeigte von allen getesteten Materialien die beste katalytische Wirksamkeit zur Sulfidoxidation. Die Sulfidumsetzung lief sowohl bei höheren pH-Werten als auch mit zunehmender Temperatur schneller ab. Anhand von Untersuchungen zum Einfluss des pH-Werts konnte bestätigt werden, dass eine katalytische Wirksamkeit nur für die Oxidation der Sulfid-Spezies HS- und S2- besteht. Mit Aktivkohle konnte ebenfalls eine katalytische Sulfidumsetzung erzielt werden, jedoch lag die Aktivität hier im Vergleich zum CoTPP deutlich niedriger. Bei allen getesteten katalytisch wirksamen Materialien entstand als vorrangiges Reaktionsprodukt Schwefel, gebildete Schwefel-Sauerstoff-Verbindungen wie Sulfat und Thiosulfat waren von untergeordneter Bedeutung. Die Untersuchungen zeigten, dass Acetylen Black aufgrund der sehr geringen Teilchengröße technisch kaum einsetzbar ist, weshalb weitere Trägermaterialien erprobt wurden. Im Gegensatz zu Aktivkohle oder Anthrazit erwiesen sich Weichfilze, insbesondere der Sigratherm Kohlenstoff-Weichfilz (KFA-Filz), als sehr gut geeignete Trägermaterialien. Beim Einsatz von Aktivkohle lagerte sich der gebildete Schwefel in den Porenräumen ab, was zu einer erheblichen Verringerung der katalytischen Aktivität führte. Dagegen wurde unter Verwendung des modifizierten Filzmaterials auch bei sehr langen Laufzeiten (bis 3000 Stunden) keine Abnahme der katalytischen Wirksamkeit beobachtet. Durch diese Katalysatormatrix konnte somit die Deaktivierung des Katalysators durch elementaren Schwefel verhindert werden. Bei abschließenden Versuchen unter Verwendung einer kleintechnischen Versuchsanlage konnte gezeigt werden, dass der Katalysator für den großtechnischen Einsatz geeignet ist. Im Vergleich zur Aktivkohle sind zwar größere Investitionskosten notwendig, andererseits können mit dem CoTPP-Material deutlich längere Laufzeiten realisiert werden. Aufgrund seiner guten technischen Handhabbarkeit ist der modifizierte KFA-Filz sowohl in kleinen dezentralen Anlagen (ländliche Siedlungen) als auch in größeren Wasserwerken einsetzbar. Zusätzliche Chemikalien sind für den Betrieb eines solchen Filters nicht erforderlich. Eine weitere Verbesserung der Sulfidentfernung wird bei langen Filterlaufzeiten durch sulfidoxidierende Bakterien bewirkt. Das Ziel, einen effizienten, technisch einsetzbaren Katalysator zur oxidativen Sulfidentfernung aus Wässern zu entwickeln, wurde somit erreicht. / Hydrogen sulfide often occurs in groundwater of arid areas. Because of its malodour, H2S containing water cannot be used as drinking water without treatment. Aeration as the most common treatment technique is less effective and leads to nasty odour of ambient air. Catalytic oxidation could be an alternative. The aim of this work was to develop and to optimize a technically applicable oxidation catalyst as well as to test its applicability under practical conditions. Various N4-chelates (e. g. porphyrins), which are frequently used for the reduction of oxygen in fuel cells, were evaluated for catalytic oxidation of sulfide at selected boundary conditions and process parameters using batch and column experiments. The new catalysts should be characterized in comparison with other materials. The oxidation kinetics, the long-time stability of the catalyst and the composition of oxidation products were the main criteria used for catalyst assessment. Cobalt tetraphenylporphyrin (CoTPP) showed the highest catalytic activity of all tested materials. The rate of sulfide transformation increased significantly with increasing temperature and at pH values higher than 6. A catalyst suitable for technical use in fixed-bed reactors was obtained by coating of a supporting material (carbon felt KFA) with the active substance. For all investigated materials, sulfur was found to be the main reaction product of the sulfide oxidation. In contrast to activated carbon, which showed catalytic activity for sulfide oxidation too, modified KFA felt materials were not blocked and deactivated by formed sulfur, even after long-term use. The new catalyst is well qualified for a stable oxidation of sulfide in water. In comparison to activated carbon, higher investment costs are required, but the carbon felt supported porphyrin has a significant longer lifetime. Because of its easy use, modified KFA felt is applicable both in small local plants and in large waterworks. There is no necessity to add chemicals or to install complex control equipment. As a positive side-effect, further improvement of sulfide elimination caused by sulfide-oxidizing bacteria was found during long filter run times.

No description available.

Poröse Materialien zeichnen sich durch hohe spezifische Oberflächen bzw. hohe spezifische Porenvolumina aus. Dies macht sie zu geeigneten Kandidaten für die Gasspeicherung, Stofftrennung und die heterogene Katalyse, die Hauptanwendungsgebiete poröser Materialien. Um poröse Materialien hinsichtlich der eben genannten Anwendungsfelder zu optimieren ist es von entscheidender Bedeutung, sie hinsichtlich ihrer jeweiligen Anwendung maßzuschneidern. Eine Klasse hochporöser Materialien, bei der das Maßschneidern der Poren möglich ist, ist die der metallorganischen Gerüstverbindungen [engl. Metal-Organic Frameworks (MOFs)]. MOFs zeichnen sich durch einen modularen Aufbau aus, der ein systematisches Design der Poren erlaubt. Auch poröse Polymere können durch Funktionalisierung der entsprechenden Monomere hinsichtlich verschiedener Anwendungsgebiete gezielt synthetisiert werden. Ein Ziel dieser Arbeit war die Integration des Metalls Rhodium als knotenbildendes Element in ein MOF. Dazu wurde Rhodium(II)-acetat, welches bereits das Schaufelradmotiv enthält, mit den trifunktionellen Carbonsäuren Trimesinsäure und 4,4´,4´´ Benzen-1,3,5-triyl-tribenzoesäure zu den MOFs DUT 82 und DUT 83 umgesetzt. Das Schaufelradmotiv als sekundäre Baueinheit in DUT-82 konnte durch röntgenabsorptionspektroskopische Untersuchungen nachgewiesen werden. Nach überkritischem Trocknen gefolgt von thermischer Aktivierung zeigten DUT-82 und DUT-83 eine permanente Porosität mit spezifischen BET-Oberflächen von bis zu 1150 m2g-1. Weiterhin konnte für DUT-82 eine sehr hohe Affinität zu Kohlenmonoxid, die selten für MOFs beobachtet wird, nachgewiesen werden. Berechnungen der Adsorptionsenthalpie ergaben bei niedrigen Beladungen einen Wert von ungefähr 50 kJmol-1, was für eine Chemisorption von Kohlenmonoxid an DUT-82 bei niedrigen Drücken spricht. Weiterhin zeigten katalytische Untersuchungen, dass sich DUT-82 als heterogener Hydrierkatalysator eignet. In einer Modellreaktion konnte Styrol erfolgreich zu Ethylbenzen umgesetzt werden. In einem weiteren Teil der Arbeit sollte ein MOF synthetisiert werden, das Stabilität und eine hohe Kapazität für Schwefelwasserstoff miteinander vereint. Eine Klasse bereits bekannter MOFs mit hoher Stabilität basiert auf dem [Zr6O4(OH)4]12+-Cluster. Durch Kombination des [Zr6O4(OH)4]12+-Clusters mit Bipyridindicarboxylat konnte das MOF UiO-67(bipy) hergestellt werden, welches isostrukturell zu UiO 67 ist. Untersuchungen an UiO 67(bipy) zeigten, dass das unbeladene Netzwerk keinen Schwefelwasserstoff adsorbiert. Die Bipyridinfunktionalität wurde anschließend für die permanente Integration weiterer Metallzentren (Metall = Cu, Ni, Co) genutzt. Dazu wurde UiO-67(bipy) zu wässrigen oder ethanolischen Metallsalzlösungen gegeben und es kam zur Adsorption der Metallsalze aus der Flüssigphase. Durch die postsynthetische Integration der Metallsalze konnte die Adsorptionskapazität der resultierenden Metallsalz@UiO-67(bipy)-Materialien für Schwefelwasserstoff bis auf 8 Gew.% gesteigert werden. Neben Adsorption und Katalyse ist die Sensorik ein weiteres Anwendungsfeld von MOFs. Eine organische Einheit, die sich als sensitive Komponente für eine Integration in ein MOF anbietet, ist Dihydro-1,2,4,5-tetrazin, das zu 1,2,4,5-Tetrazin oxidiert werden kann. Das bemerkenswerte Merkmal dieser Reaktion ist der radikale Farbwechsel von Gelb nach Pink. Nach erfolgreicher Synthese der Dihydro-1,2,4,5-tetrazindicarbonsäure sollte sie durch Kombination mit dem [Zr6O4(OH)4]12+-Cluster zu einem UiO-66 analogen Netzwerk in ein stabiles Netzwerk integriert werden. Da die direkte Syntheseroute eines UiO-66 analogen Netzwerks nicht zum Erfolg führte, wurde die mildere Variante des Linkeraustauschs gewählt. Über diese Route konnte das Dihydro-1,2,4,5-tetrazindicarboxylat erfolgreich partiell in das UiO-66 Netzwerk integriert werden. Anschließende Untersuchungen zeigten, dass die in das Netzwerk eingebaute Dihydro-1,2,4,5-tetrazin-Einheit sowohl in der Flüssig- als auch in der Gasphase erfolgreich oxidiert werden kann, was durch UV/vis-Messungen belegt werden konnte. Eine weitere Klasse poröser Materialien, die hervorragende chemische Stabilität aufweist, ist die der konjugierten Triazin-Netzwerke. Sie entstehen durch Cyclotrimerisierung multifunktioneller Nitrile. Durch geschickte Wahl der Monomere ist eine Funktionalisierung der Triazin-Netzwerke möglich. Um ein chirales Triazin-Netzwerk zu synthetisieren, wurde Spirobiindan erfolgreich mit Nitrilgruppen funktionalisiert. Die Umsetzung des Monomers in einer Zinkchlorid-Schmelze führte zu porösen Polymeren mit spezifischen BET-Oberflächen von bis zu 1180 m2g 1. Dabei konnte die Porengrößenverteilung des Triazin-Netzwerkes durch Variation des Verhältnisses von Zinkchlorid zu Monomer gezielt eingestellt werden. Die Polymersynthese erfolgte mit einer racemischen Mischung des Monomers und führte somit zu einem achiralen Polymer. Erste Untersuchungen zeigten, dass eine Trennung des racemisch vorliegenden Monomers mittels Hochleistungsflüssigchromatographie möglich ist. Die Imidazoliumgruppe ist eine weitere Baueinheit, die in Triazin-Polymere integriert werden sollte, da sie leicht in ein N-Heterocyclisches Carben überführt werden kann. N-Neterocyclische Carbene können direkt als Katalysator bzw. als Ligand für eine Vielzahl von Metallen zur Generierung eines Katalysators genutzt werden. Über mehrstufige Synthesen konnten zwei nitrilfunktionalisierte Imidazoliumsalze hergestellt werden. Die anschließende Cyclotrimerisierung führte zu porösen Polymeren mit spezifischen BET-Oberflächen von bis zu 680 m2g-1. Erste katalytische Untersuchungen zum Einsatz dieser Triazin-Netzwerke in Umpolungsreaktionen von Zimtaldehyd mit 2,2,2 Trifluoracetophenon zeigten jedoch lediglich einen geringen Umsatz zum gewünschten Produkt.

As atividades humanas em bacias hidrográficas introduzem nos cursos de água nutrientes que aceleram o processo natural de eutrofização, favorecendo a ocorrência de florações de algas e cianobactérias. Estas florações se caracterizam por um crescimento explosivo destes microrganismos. Entre os diversos impactos negativos trazidos pelas florações está a emissão potencial dos compostos 2-metilisoborneol (MIB) e geosmina (GEO), os quais conferem gosto e odor de mofo e terra a água. Estes compostos não são totalmente removidos pelos processos convencionais de tratamento de água – clarificação química, filtração em meio granular e desinfecção com cloro, e permanecem na água até seu consumo, ocasionando alto índice de rejeição do produto por parte da população consumidora. Desta forma, a pesquisa foi planejada para avaliar alternativas de processos de tratamento visando à remoção de compostos odoríferos na água. Além de MIB e geosmina, foram feitas investigações relativas a remoção de ferro (Fe+2), manganês (Mn+2) e enxofre (H2S), nos processos estudados. Estas formas são normalmente encontradas em ambientes redutores, como águas subterrâneas e no hipolímnio de lagos e reservatórios, podendo contribuir para a deterioração das características organolépticas da água, ocasionando gosto e odores desagradáveis na água potável. Os processos estudados na pesquisa foram aeração em cascata, dessorção gasosa e nanofiltração. Os mecanismos do primeiro e segundo processos são: a oxidação de formas reduzidas e a dessorção de compostos voláteis e gases da água para o ar. O sistema de nanofiltração remove contaminantes da água através de retenção física imposta pelo tamanho dos poros da membrana. / Human activities in watersheds introduce nutrients to water bodies, accelerating the natural process of eutrophication and favoring the occurrence of algae and cyanobacterial blooms. The blooms are characterized by explosives growths of those microorganisms. Among the several negative impacts brought by the blooms is the potential emission of the compounds 2-methylisoborneol (MIB) and geosmin (GEO), which confer earthy and moldy taste and odor to drinking water. MIB and GEO are not completely removed by the conventional water treatment processes – chemical clarification, granular filtration and chorine disinfection, causing consumer’s rejection of the distributed drinking water This research was planned to evaluate the capability of alternative treatment processes to remove odorous compounds from water. Besides MIB and geosmin, the research encompassed tests with iron (Fe+²), manganese (Mn+²) and hydrogen sulfide (H2S). These species are usually found in reduced environments such as lake and reservoir hypolimnion and groundwater. They can cause problems associated with color, taste and odor in drinking water. Processes studied in the research were cascade aeration, air stripping and nanofiltration. Prevailing mechanisms in the first two processes are oxidation of the reduced forms by air oxygen and stripping of volatile compounds and gases dissolved in water to air. Nanofiltration systems remove contaminants dissolved in water by physical retention imposed by the membrane pore size.

As atividades humanas em bacias hidrográficas introduzem nos cursos de água nutrientes que aceleram o processo natural de eutrofização, favorecendo a ocorrência de florações de algas e cianobactérias. Estas florações se caracterizam por um crescimento explosivo destes microrganismos. Entre os diversos impactos negativos trazidos pelas florações está a emissão potencial dos compostos 2-metilisoborneol (MIB) e geosmina (GEO), os quais conferem gosto e odor de mofo e terra a água. Estes compostos não são totalmente removidos pelos processos convencionais de tratamento de água – clarificação química, filtração em meio granular e desinfecção com cloro, e permanecem na água até seu consumo, ocasionando alto índice de rejeição do produto por parte da população consumidora. Desta forma, a pesquisa foi planejada para avaliar alternativas de processos de tratamento visando à remoção de compostos odoríferos na água. Além de MIB e geosmina, foram feitas investigações relativas a remoção de ferro (Fe+2), manganês (Mn+2) e enxofre (H2S), nos processos estudados. Estas formas são normalmente encontradas em ambientes redutores, como águas subterrâneas e no hipolímnio de lagos e reservatórios, podendo contribuir para a deterioração das características organolépticas da água, ocasionando gosto e odores desagradáveis na água potável. Os processos estudados na pesquisa foram aeração em cascata, dessorção gasosa e nanofiltração. Os mecanismos do primeiro e segundo processos são: a oxidação de formas reduzidas e a dessorção de compostos voláteis e gases da água para o ar. O sistema de nanofiltração remove contaminantes da água através de retenção física imposta pelo tamanho dos poros da membrana. / Human activities in watersheds introduce nutrients to water bodies, accelerating the natural process of eutrophication and favoring the occurrence of algae and cyanobacterial blooms. The blooms are characterized by explosives growths of those microorganisms. Among the several negative impacts brought by the blooms is the potential emission of the compounds 2-methylisoborneol (MIB) and geosmin (GEO), which confer earthy and moldy taste and odor to drinking water. MIB and GEO are not completely removed by the conventional water treatment processes – chemical clarification, granular filtration and chorine disinfection, causing consumer’s rejection of the distributed drinking water This research was planned to evaluate the capability of alternative treatment processes to remove odorous compounds from water. Besides MIB and geosmin, the research encompassed tests with iron (Fe+²), manganese (Mn+²) and hydrogen sulfide (H2S). These species are usually found in reduced environments such as lake and reservoir hypolimnion and groundwater. They can cause problems associated with color, taste and odor in drinking water. Processes studied in the research were cascade aeration, air stripping and nanofiltration. Prevailing mechanisms in the first two processes are oxidation of the reduced forms by air oxygen and stripping of volatile compounds and gases dissolved in water to air. Nanofiltration systems remove contaminants dissolved in water by physical retention imposed by the membrane pore size.

Les piles à combustible à membrane échangeuse de protons (PEMFC) sont sensibles aux polluantsde l’hydrogène et de l’air. Cette étude s’est focalisée sur l’impact du monoxyde de carbone (CO) et dusulfure d’hydrogène (H2S), deux polluants majeurs dans l’hydrogène (H2), suivant une approchecombinant expériences et modélisation.Le volet expérimental a consisté à étudier l’effet de la concentration des polluants individuels et enmélange et des chargements en catalyseurs, pour différents modes de fonctionnement. Cette étude amis en lumière un impact sur les deux électrodes (anode et cathode) dû à la distribution hétérogènedes polluants à la surface de l’anode et à la désactivation de la partie de la cathode en regard. Deplus, dans le cas d’un empoisonnement par H2S, cette étude a montré que la tension de cellule atteintun état quasi-stationnaire, en mode galvanostatique, ce qui n’avait jamais été mis en évidence dans lalittérature.Dans l’approche de modélisation multi-échelles, le couplage de l’électrochimie et de la fluidique ainsique le développement de différentes « briques » du modèle ont permis de perfectionner la descriptiondes phénomènes physico-chimiques. Le modèle permet maintenant de simuler le fonctionnementd’une cellule de pile à combustible dans les conditions opératoires réelles, en intégrant les cinétiquesd’empoisonnement du platine par CO et H2S.Enfin, la comparaison des données expérimentales et des simulations a montré des résultats trèssatisfaisants appuyant certains arguments pour l’interprétation de l’impact des impuretés de H2. / Protons exchange membrane fuel cells (PEMFC) are sensitive to hydrogen and air pollutants. Thisstudy is focused on the impact of carbon monoxide (CO) and hydrogen sulfide (H2S) which are twomajor impurities of hydrogen. A combined experimental and modeling approach has been followed.The experimental part consisted in studying the effect of the concentration of individual pollutants andmixtures, and the effect of catalyst loading, for different operating modes. This work has highlighted animpact on both electrodes (anode and cathode) due to a heterogeneous distribution of the pollutantson the anodic surface area and to a deactivation of the opposite cathodic surface area. Furthermore,in the case of H2S poisoning, this study has shown that the cell voltage can reach a quasi-steadystate, in galvanostatic mode, which had never been highlighted in the literature.In the multi-scales modeling approach, a coupling of the electrochemistry and fluidics as well as thedevelopment of new modules of the model have allowed improving the description of the physicochemicalphenomena. As a consequence, the model simulates a fuel cell in real operating conditions,including the kinetics of platinum poisoning by CO and H2S.Finally, experimental data and simulated data were compared and they showed satisfactory anduseful results for the understanding of the impact of H2 impurities.

Com o decorrer dos anos o consumo de petróleo e seus derivados aumentou significativamente e com isso houve a necessidade de se investir em pesquisas para descobertas de novas jazidas de petróleo como o pré-sal. Porém, não apenas a localização dessas jazidas deve ser estudada, mas, também, sua forma de exploração. Essa exploração e extração, na maioria das vezes, se dão em ambientes altamente corrosivos e o transporte do produto extraído é realizado através de tubulações de aço de alta resistência e baixa liga (ARBL). Aços ARBL expostos a ambientes contendo H2S e CO2 (sour gas) sofrem corrosão generalizada que promovem a entrada de hidrogênio atômico no metal, podendo diminuir sua tenacidade e causar falha induzida pela presença de hidrogênio (Hydrogen Induced Cracking HIC), gerando falhas graves no material. Tais falhas podem ser desastrosas para o meio ambiente e para a sociedade. O objetivo deste trabalho é estudar a tenacidade, utilizando ensaio Charpy, de um tubo API 5L X65 sour após diferentes tempos de imersão em uma solução saturada com H2S. O eletrólito empregado foi a solução A (ácido acético contendo cloreto de sódio) da norma NACE TM0284 (2011), fazendo-se desaeração com injeção de N2, seguida de injeções de H2S. Os materiais foram submetidos a: ensaios de resistência a HIC segundo a norma NACE TM0284 (2011) e exames em microscópio óptico e eletrônico de varredura para caracterização microestrutural, de inclusões e trincas. As amostras foram submetidas a imersão em solução A durante 96h e 360h, sendo que, após doze dias do término da imersão, foram realizados os ensaios Charpy e exames fractográficos. Foram aplicados dois métodos: o de energia absorvida e o da expansão lateral, conforme recomendações da norma ASTM E23 (2012). As curvas obtidas, em função da temperatura de impacto, foram ajustadas pelo método da tangente hiperbólica. Esses procedimentos foram realizados nas duas seções do tubo (transversal e longitudinal) e permitiram a obtenção dos seguintes parâmetros: energias absorvidas e expansão lateral nos patamares superior e inferior e temperaturas de transição dúctil-frágil (TTDF) em suas diferentes definições, ou seja, TTDFEA, TTDFEA-DN, TTDFEA-FN, TTDFEL, TTDFEL-DN e TTDFEL-FN (identificação no item Lista de Abreviaturas e Siglas). No exame fractográfico observou-se que o material comportou-se conforme o previsto, ou seja, em temperaturas mais altas ocorreu fratura dúctil, em temperaturas próximas a TTDF obteve-se fratura mista e nas temperaturas mais baixas observou-se o aparecimento de fratura frágil. Os resultados mostraram que quanto maior o tempo de imersão na solução A, menor é a energia absorvida e a expansão lateral no patamar superior, o que pode ser explicado pelo (esperado) aumento do teor de hidrogênio em solução sólida com o tempo de imersão. Por sua vez, os resultados mostraram que há tendência à diminuição da temperatura de transição dúctil-frágil com o aumento do tempo de imersão, particularmente, as TTDFEA-DN e TTDFEL-DN das duas seções do tubo (longitudinal e transversal). Esse comportamento controverso, que pode ser denominado de tenacificação com o decorrer do tempo de imersão na solução A, foi explicado pelo aparecimento de trincas secundárias durante o impacto (Charpy). Isso indica uma limitação do ensaio Charpy para a avaliação precisa de materiais hidrogenados. / Over the years the consumption of crude oil and its derivatives increased significantly, creating the necessity to invest in research to discover new sources of pre-salt crude oil. However, not only the location of these deposits should be studied, but also its extraction. This exploration and extraction, in most cases, occur in highly corrosive environments and the transport of the extracted product is performed by high strength low alloy steel pipes (HSLA). HSLA steels exposed to environments containing CO2 and H2S (sour gas) suffer general corrosion that promotes the diffusion of atomic hydrogen into the metal structure, which may decrease its toughness and induce cracks by the presence of hydrogen (Hydrogen Induced Cracking - HIC), leading the material to severe failures. Such events can be disastrous for the environment and the society. The objective of this work is to study the toughness using Charpy Impact Tests on an API 5L X65 sour service steel pipe, submitted to different immersion times in a H2S saturated solution. The used electrolyte was the NACE TM0284 (2011) solution A (acetic acid containing sodium chloride), with deaeration by N2 injection followed by H2S injection. The materials were submitted to HIC resistance tests according to NACE TM0284 (2011) standard and examination by optical microscopy and scanning electron microscopy for microstructural inclusions and cracks characterization. The samples were immersed in the solution for 96h and 360h and after twelve days of immersion, Charpy tests and fracture analysis were performed. Two analytical methods were applied to Charpy tests results: the energy absorbed and lateral expansion, as recommended by the ASTM E23 (2012). The obtained curves, that are a function of impact temperature, were adjusted by the hyperbolic tangent method. This procedure was performed in two different orientations in the pipe (transverse and longitudinal) and allowed the determination of the following parameters: energy absorbed and lateral expansion in the upper and lower levels and ductile-to-brittle transition temperatures (DBTT) in its different definitions: DBTTAE, DBTTAE-DN, DBTTAE-FN, DBTTLE, DBTTLE-DN e DBTTLE-FN. Fracture analysis revealed that the material behaved as expected, meaning that at higher temperatures ductile fracture occurred, at temperatures near DBTT it was obtained a mixed fracture and at lower temperatures it was observed the presence of brittle fracture. Results showed that when the immersion time in the solution was higher, the energy absorbed in upper shelf decreases, and also lateral expansion in upper shelf decreases, which may be explained by the (expected) increase of hydrogen level in solid solution, induced by the immersion time. It was found that there is a tendency of the ductile-to-brittle transition temperature to be lower with the increase of immersion time, particularly the DBTTAE-DN and DBTTLE-DN of the two pipe sections (longitudinal and transversal). This controversial behavior, which may be defined as the toughening by the increase of immersion time in the solution A, was explained by the appearance of secondary cracks during impact test (Charpy). This indicates a limitation of the Charpy test for the accurate characterization of hydrogenated materials, concerning toughness.

Neste trabalho investigamos o efeito de doadores de H2S no prurido agudo mediado por PAR-2 em camundongos. A injeção i.d. do agonista PAR-2 SLIGRL-NH2, induziu prurido que não foi afetado pelo pré-tratamento com o antagonista H1 pirilamina. A coinjeção dos doadores de H2S GYY4137 (lento) ou NaHS (espontâneo) com SLIGRL-NH2 reduziu significativamente o prurido (P<0,05). A glibenclamida (bloqueador de canais KATP) e o SNP (doador de NO), mas não o ODQ (inibidor da sGC), evitaram estes efeitos. O antagonista TRPA1 HC-030031 reduziu significativamente o prurido induzido pelo SLIGRL-NH2 (P<0,05), mas o prurido induzido pelo agonista TPRA1 AITC não foi afetado por NaHS. Ensaios de Western blot mostraram que ambos PAR-2 e TRPA1 são expressos constitutivamente na pele de camundongos. Nossos dados mostram que o prurido secundário à ativação do PAR-2 pode ser reduzido por H2S, atuando via a abertura dos canais KATP e ativação da via NO-GMPc. Ademais, o receptor TRPA1 pode mediar o prurido induzido por SLIGRL-NH2, mas o H2S não interfere nesta via. / In this study we investigated the effect of H2S donors in PAR-2-mediated acute pruritus in mice. The i.d. injection of the PAR-2 agonist SLIGRL-NH2 induced itching that was unaffected by pre-treatment with the H1 antagonist pyrilamine. Co-injection of the H2S donors GYY4137 (slow) or NaHS (spontaneous) with SLIGRL-NH2 significantly reduced pruritis (P <0.05). Glibenclamide (a KATP channel blocker) and SNP (a NO donor), but not ODQ (a sGC inhibitor) prevented these effects. The TRPA1 antagonist HC-030031 significantly reduced SLIGRL-NH2-induced pruritus (P<0.05), but the pruritus induced by the TPRA1 agonist AITC was unaffected by NaHS. Western blot assays showed that both TRPA1 and PAR-2 are constitutively expressed in the mouse skin. Our data show that itching secondary to PAR-2 activation can be reduced by H2S which acts via the opening of KATP channels and activation of the NO-cGMP pathway. Furthermore, TRPA1 receptors may mediate SLIGRL-NH2-induced pruritus, however, H2S does not interfere with this pathway.

As atividades humanas em bacias hidrográficas introduzem nos cursos de água nutrientes que aceleram o processo natural de eutrofização, favorecendo a ocorrência de florações de algas e cianobactérias. Estas florações se caracterizam por um crescimento explosivo destes microrganismos. Entre os diversos impactos negativos trazidos pelas florações está a emissão potencial dos compostos 2-metilisoborneol (MIB) e geosmina (GEO), os quais conferem gosto e odor de mofo e terra a água. Estes compostos não são totalmente removidos pelos processos convencionais de tratamento de água – clarificação química, filtração em meio granular e desinfecção com cloro, e permanecem na água até seu consumo, ocasionando alto índice de rejeição do produto por parte da população consumidora. Desta forma, a pesquisa foi planejada para avaliar alternativas de processos de tratamento visando à remoção de compostos odoríferos na água. Além de MIB e geosmina, foram feitas investigações relativas a remoção de ferro (Fe+2), manganês (Mn+2) e enxofre (H2S), nos processos estudados. Estas formas são normalmente encontradas em ambientes redutores, como águas subterrâneas e no hipolímnio de lagos e reservatórios, podendo contribuir para a deterioração das características organolépticas da água, ocasionando gosto e odores desagradáveis na água potável. Os processos estudados na pesquisa foram aeração em cascata, dessorção gasosa e nanofiltração. Os mecanismos do primeiro e segundo processos são: a oxidação de formas reduzidas e a dessorção de compostos voláteis e gases da água para o ar. O sistema de nanofiltração remove contaminantes da água através de retenção física imposta pelo tamanho dos poros da membrana. / Human activities in watersheds introduce nutrients to water bodies, accelerating the natural process of eutrophication and favoring the occurrence of algae and cyanobacterial blooms. The blooms are characterized by explosives growths of those microorganisms. Among the several negative impacts brought by the blooms is the potential emission of the compounds 2-methylisoborneol (MIB) and geosmin (GEO), which confer earthy and moldy taste and odor to drinking water. MIB and GEO are not completely removed by the conventional water treatment processes – chemical clarification, granular filtration and chorine disinfection, causing consumer’s rejection of the distributed drinking water This research was planned to evaluate the capability of alternative treatment processes to remove odorous compounds from water. Besides MIB and geosmin, the research encompassed tests with iron (Fe+²), manganese (Mn+²) and hydrogen sulfide (H2S). These species are usually found in reduced environments such as lake and reservoir hypolimnion and groundwater. They can cause problems associated with color, taste and odor in drinking water. Processes studied in the research were cascade aeration, air stripping and nanofiltration. Prevailing mechanisms in the first two processes are oxidation of the reduced forms by air oxygen and stripping of volatile compounds and gases dissolved in water to air. Nanofiltration systems remove contaminants dissolved in water by physical retention imposed by the membrane pore size.