M. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology. / In chemical bath deposition (CBD) method, deposition of metal chalcogenide semiconducting thin films occurs due to substrate maintained in contact with a dilute chemical bath containing metal and chalcogenide ions. Semiconducting nickel sulphide (NiS) and iron sulphide (FeS) thin films have been prepared on a glass substrate by varying the deposition parameters such as the concentration of solutions, deposition time, temperature and pH. Multi-layered thin films were deposited on glass substrate and the spin-cast conductive polymer, poly (3.4-ethylenedioxythiopene) polystyrene sulfonate (PEDOT: PSS) was intercalated. The characterization of the films was carried out using UV-Vis spectroscopy, scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM) and X-ray diffraction (XRD). Single layer nickel sulphide was deposited at room temperature, pH 10 and the deposition period of 3 hours, triethanolamine was used as the complexing agent. Iron sulphide was deposited for 6 hours at 70 °C with the pH of 2.5 using EDTA as a complexing agent. Generally the iron and nickel sulphide were prepared from their respective nickel or iron salt and the thiourea or thiosulfate as a source of sulphide ions in solution. SEM and AFM results show that the FeS film is evenly coated and has uniform grain size with the roughness of ~22.4 nm and thickness of ~23.8 nm. The optical absorption analysis of FeS showed the band gap energy of ~2.9 eV which blue shifted from the bulk. The EDX analysis confirms the compositions of iron and sulphur in FeS films. XRD pattern showed amorphous films for both FeS and NiS thin films due to the amorphous nature of the glass substrate. The optical data of NiS film were analysed and exhibited the band gap energy of ~3.5 eV and ~3.3 eV for successive ionic layer adsorption and reaction (SILAR), which is the modified CBD, both blue shifted from the bulk. The films were observed to have thickness value of ~35.7 nm and ~2.3 nm SILAR with the roughness of ~112.5 nm and ~35.4 nm SILAR from AFM results. SEM confirmed the uniformly distributed film presented by AFM analysis. The chemical composition of Ni and S were confirmed by EDX spectra. The PEDOT: PSS was intercalated between the FeS as the first layer and NiS as the top layer which gave the thickness of ~18.7 nm and roughness of ~115.2 nm from AFM analysis. PEDOT: PSS acted as a passive layer that protects and stabilize the FeS layer and NiS as the third active layer which enhanced the optical absorption of the film when using SILAR method for solar application.

In the early 1990’s, a lot of work was focused on extending the kraft cook to a low lignin content (low kappa number). The driving force was the need to further reduce the environmental impact of the bleaching, as less delignification work would be needed there. However, the delignification during the residual phase of a kraft cook is very slow and, due to its poor selectivity, it is a limiting factor for the lignin removal. If the amount of lignin reacting according to the residual phase could be reduced, it would be possible to improve the selectivity of the kraft cook. In the work described in this thesis, special attention has been given to the activation energy of the slowly reacting residual phase of a kraft cook on softwood raw material and to the influence of different cooking parameters on the amount of the residual phase lignin. The activation energy of the residual phase delignification of the kraft cook was shown to be higher than that of the bulk phase delignification. In order to decrease the amount of residual phase lignin, it was essential to have a high concentration of hydrogen sulphide ions when cooking with a low hydroxide concentration. It was also important to avoid a high sodium ion concentration when cooking with low hydroxide and low hydrogen sulphide ion concentrations. Furthermore, it was demonstrated that dissolved wood components had a positive effect on the delignification rate in the bulk phase of a kraft cook. The influence of different cooking parameters in the extended softwood kraft process on the bleachability (i.e. the ease with which the pulps can be bleached to a target brightness) of the manufactured pulp was also investigated. If variations in bleachability were seen, an attempt would also be made to find chemical reasons to explain the differences. It was difficult to establish clear relationships between the chemical structures of the residual lignin and the bleachability of the pulp. However, it was seen that the higher the content of β-aryl ether structures in the residual lignin after cooking, the better was the QPQP*-bleachability. In the middle/end of the 1990’s, the focus moved from extended cooking to efficient utilisation of the wood raw material, e.g. by interrupting the kraft cook at higher kappa number levels and choosing appropriate cooking conditions to maximise the cooking yield. A high cooking yield often leads to a somewhat higher hexenuronic acid (HexA) content of the pulp at a given kappa number. Therefore additional attention was devoted to how the HexA content and carbohydrate composition were affected, e.g. by a set of cooking parameters. Performing these studies it was also important to investigate the effects of a low HexA (after cooking) strategy on such vital factors as the cooking yield, the bleachability and the yellowing characteristics of the pulp obtained. It proved to be difficult to significantly reduce the HexA content in a kraft pulp by altering the cooking conditions for both softwood and the hardwood Eucalyptus Globulus. A reduction in HexA content can be achieved by extending the cook to lower kappa numbers, or by using a high hydroxide concentration, a low hydrogen sulphide concentration or a high sodium ion concentration. However, neither of these strategies is attractive for industrial implementation since they would result in an extensive loss of yield, viscosity and strength. / <p>QC 20100825</p>

Ganglion cell death in glaucoma is caused by a variety of insults that include ischemia, insufficient neurotrophic support and oxidative stress. Experimental studies were therefore conducted on cell cultures to determine how serum deprivation (to mimic insufficient neurotrophic support) or oxidative glutamate toxicity (GB), cause oxidative stress and induce retinal cell death. Moreover, studies were carried out to deduce whether selected sulphur containing compounds can blunt any negative influences to cells in culture and/or a defined ischaemic insult to the rat retina in situ, as this might suggest their use for the treatment of glaucoma. Serum deprivation and GB caused generation of reactive oxygen species (ROS) and apoptosis-like death to transformed retinal ganglion cells (RGC-5 cells). RGC-5 cells were more susceptible to the detrimental effects of GB than serum deprivation. RGC-5 cells subjected to serum deprivation appear to die by mechanisms that resemble classical apoptosis more closely than that caused by GB and the phase between the maximal generation of ROS and cell death were different. Cell death caused by serum deprivation was caspase-dependent but this was not the case for GB. Moreover, of the two sulphur compounds sulbutiamine and N-acetyl cysteine (NAC), sulbutiamine blunts the effect of serum deprivation more effectively. In addition, the pan caspase inhibitor z-VAD-fmk attenuated the negative effect of serum deprivation to RGC-5 cells while the necroptosis inhibitor (necrostsatin-1) counteracted solely the insult of GB. The sulphur containing compounds, ACS1 and ACS 67 which release hydrogen sulphide (H2S) slowly and NAC (a pro-cysteine GSH precursor) attenuated GB-induced cell death of RGC-5 cells. In contrast, sulbutiamine (a lipophilic thiolic thiamine derivative) was particularly effective in protecting RGC-5 cells from an insult of serum deprivation. Moreover, all of the sulphur compounds directly sequestered different types of ROS but with varying efficiency. Common features by which all tested sulphur containing agents seem to elicit a mode of action include the stimulation of GSH and the antioxidant enzyme glutathione-S-transferase (GST) as well as to scavenge excess free radicals. Moreover, the slow release of H₂S from the ACS compounds appears to protect cells from oxidative stress through increasing the level of GSH, modulation of the cystine uptake transporter xCT, stimulation of the oxidative stress related transcription factor Nrf2 and the stimulation of pro-survival signalling pathways. The slow releasing H₂S sulphur compound ACS67 also counteracts a number of detrimental influences to the rat retina in situ because of ischemia/reperfusion that includes damage to their ganglion cells. This suggests that such sulphur compounds might find a use in the treatment of glaucoma where ischemia probably plays a part in the disease process.

Mid-ocean ridge hydrothermal systems play an important role in the cycling of energy and mass between the solid earth and oceans. The on-axis low-temperature diffuse fluids (temperature lower than ~100 °C) carry ~90% of the on-axis heat fluxes, but diffuse fluids generation is poorly constrained. This study uses the abundance of the chalcophile elements, which form metal-sulphides in the rock record, to test models for diffuse fluids generation. These include mixing between seawater and high-temperature hydrothermal fluids and conductive cooling of high- temperature hydrothermal fluids. This thesis determined the concentrations of the elements of interest (As, Mo, Ag, Cd, Sn, and Tl) in geological reference materials using standard addition method in ICP-MS. These values were used to calibrate the analysis of samples from Pito Deep to trace the abundance of these elements within the upper oceanic crust. The results show that the Zn, Cu, As, Ag, Cd, Tl, and Pb are generally depleted in sheeted dikes and enriched in the lava unit and/or the transition zone, which is consistent with previous studies on fast-spreading EPR crust at Hole 504B, Hess Deep and Hole 1256D. The enrichment of these elements in the lava unit and/or the transition zone suggests that cooling high-temperature hydrothermal fluids to form diffuse fluids occurred in this iii iv area of the oceanic crust. Molybdenum and Sb are added into all units of the crust by recharging seawater. The concentrations of chalcophile elements in diffuse fluids were calculated by a mass balance. The results of this study favored a diffuse fluids generation model that involves mixing of seawater and high-temperature hydrothermal fluids. Results also show that the observed concentrations of Mo and Sb requires extra input source besides recharging seawater and oceanic crust, possibly particulates in seawater. / Graduate / juliatian2013@gmail.com

Ekobacken, Värmdö kommun, har problem med surt yt- och grundvatten med höga metallhalter. Uppmärksamheten har riktats mot berggrunden som krossats och lagrats i deponihögar. Bildningen av sur lak styrs av flertalet geokemiska egenskaper, bland annat vilka sulfidmineral som förekommer och deras kristallstruktur. Prover från Ekobacken har undersökts utifrån sulfidhalt, kristallarea för opaka mineral och surgörande potential för att kunna utröna om ett samband finns mellan kristallareafördelning och lakningsegenskaper. Proverna har mikroskopiskt undersökts i reflekterande ljus för att skilja ur vilka opaka faser som förekommer samt har tunnslip fotograferats för att bildanalysera de opaka faserna utifrån area och form. Ett statiskt laktest utfördes på proverna för att kvantifiera dess lakningsegenskaper. Resultatet visar att bergarterna bestod i stor del av kvarts, fältspat och biotit i olika fördelningar. Opaka faser som förekom var pyrit, grafit, kopparkis och magnetit. Bergarterna visade sig generellt ha hög sulfidhalt från ABA resultatet, där ett prov hade en halt på 0,61 vikt%, medan andra prov hade relativt hög bufferförmåga och därför ingen surgörande potential. Proverna som undersöktes visade sig vara likartade varandra i förhållande till kristallareafördelning av opaka faser och form. I den här studien gick ingen direkt korrelation mellan provens kristallareafördelning för opaka faser och lakningspotential att utröna / Ekobacken, Värmdö municipality, have a problem with acidic surface- and groundwater with high metal content. The attention has been directed towards the bedrock which have been crushed and stored in landfills. The production of acid drainage is controlled by multiple geochemical properties inter alia which sulphide minerals are present and the structure of crystals. Samples from Ekobacken has been collected and analysed for sulphide content, crystal-area of sulphide minerals and acidic potential to investigate if there is a correlation between crystal-area distribution and leachability. The samples were examined under reflective light microscopy to determine the different opaque phases present and the thin sections were photographed for a photo analysis regarding crystal area and shape. A static leachability test was performed to be able to quantify the samples potential to produce acidic drainage. The results show that the samples contained mostly quartz, feldspars and biotite. Opaque phases present were pyrite, graphite, chalcopyrite and magnetite. ABA results showed high sulphide content, where one sample reached 0,61 wt. % sulphide content. Other samples contained relative high ability to buffer acidic reaction and thus showed no potential to produce acidic drainage. The samples were homogenous to each other with regard of crystal-area distribution of opaque phases and aspect-ratio of individual crystals and in this study no direct correlation between the sample’s crystal-area distribution of opaque phases and potential to produce acidic drainage was apparent.

I detta arbete har polerprov framställts för att därefter undersökas med malm- och svepelektronmikroskopi (SEM) med energidispersiv röntgenspektroskopisk analys (EDS). Med dessa metoder har mineralsammansättning, strukturer och texturer identifierats och undersökts. De undersökta proverna kommer från borrkärnor genom malmzonen i Lovisagruvan i Bergslagen, södra Mellansverige. Malmen är en tabulär, silverförande Zn-Pb-sulfidmineralisering.  De kombinerade undersökningarna av polerproven visar att de huvudsakligen består av zinkblände, blyglans, kvarts, mikroklin, granat, amfibol och pyrit, vilka karakteriseras av texturer som visar på omkristallisation, heterogen deformation och lokal remobilisering. De uppvisar småskaliga texturer som sannolikt är direkt relaterade till uppkomsten av s.k. kulmalmstextur. De ingående mineralens inbördes relationer tyder på att blyglans och zinkblände bildades samtidigt och därefter, under regionalmetamorfa förhållanden, tillväxte pyrit och granat som porfyroblaster. Majoriteten av texturerna och strukturerna är sekundära och visar på en kraftig senare överprägling av malmen genom metamorfos och flerfasig deformation under olika tryck- och temperaturförhållanden. / In this project polished sections have been prepared for study by means of ore and scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS). The application of these methods allows mineralogy, structures and textures to be characterized. This was done within the EU H2020-funded project X-Mine. The studied samples are from drill cores transecting the ore zone of the Lovisa mine (Lovisagruvan), which is located in Örebro County in the Bergslagen ore province, south central Sweden. Here, a tabular, stratiform silver-bearing Zn-Pb sulphide ore is mined.  Studies of the polished ore sections show that the samples mainly contain sphalerite, galena, quartz, microcline, garnet, amphibole and pyrite, characterized by textures of recrystallisation, heterogeneous deformation and localized remobilization.  The studied samples from the main ore and exhibit textures directly related to the formation off the so-called ball ore. The textural interrelationships of the major minerals indicate that galena and sphalerite formed penecontemporaneously, and then under regional metamorphic conditions, pyrite and garnet formed as porphyroblasts. The majority of the present textures and structures are secondary, representing different stages of metamorphism and deformation under variable P-T-conditions, post-dating original ore formation. / Real-Time Mineral X-Ray Analysis for Efficient and Sustainable Mining, H2020 X-Mine, Projekt-id: 730270

O prurido, assim como a dor, é uma experiência sensorial aversiva, associada ao desejo de coçar-se. Resultados prévios deste grupo demonstraram que a injeção i.d. de moléculas doadoras do sulfeto de hidrogênio (H2S), um novo mediador endógeno, reduziu o prurido agudo e a inflamação cutânea induzidos por histamina ou composto 48/80 (C48/80) na pele dorsal de camundongos, sugerindo o envolvimento do H2S no controle do prurido mediado por aminas. Todavia, pouco se conhece sobre os mecanismos envolvidos na indução ou inibição dessa percepção sensorial (aguda ou crônica), e a participação do H2S. A fim de aprofundar esse conhecimento, os objetivos deste estudo foram:i) testar e caracterizar os mecanismos envolvidos nos efeitos protetores de diferentes moléculas doadoras de H2S (liberação rápida e lenta) sobre o prurido agudo e inflamação associada, induzidos por estímulos dependente e independente de histamina, ii) averiguar a capacidade de produção endógena de H2S e as enzimas envolvidas em sua síntese na pele murina saudável e doente, iii) padronizar um modelo de prurido crônico associado ao escore de intensidade da área inflamada na psoríase (PASI), e investigar o efeito protetor de um doador de H2S de liberação lenta (GYY4137). Utilizando camundongos Balb/C, foi realizada a avaliação do comportamento de prurido agudo e inflamação cutânea (extravasamento plasmático, influxo de neutrófilos), frente a diversos estímulos, na ausência e vigência do co- tratamento (i.d.) com doadores de H2S. A psoríase experimental foi induzida pela aplicação tópica do creme imiquimode (IMQ 5%) na pele dorsal destes, por 5 dias consecutivos, e grupos paralelos com a doença foram tratados pela via intraperitoneal (i.p.) com o GYY4137 em diferentes doses (25-100 mg/kg). Os registros do prurido e PASI foram obtidos durante a indução da psoríase e as análises bioquímicas e moleculares foram realizadas ao término do experimento. O tratamento com doses crescentes de GYY4137 (0,3 30 nmol/sitio, i.d.) inibiu o prurido agudo induzido por histamina ou cloroquina e reduziu o influxo de neutrófilos frente ao C48/80, mas não afetou o extravasamento plasmático induzido por histamina ou C48/80. O bloqueio das enzimas geradoras de H2S maximizou o prurido e o influxo de neutrófilos desencadeado por C48/80. O pré-tratamento com a glibenclamida (10 mg/kg; i.p, -30 min), bloqueador dos canais de KATP, não reverteu o efeito do doador de H2S de liberação rápida sobre o prurido agudo e inflamação induzidos por histamina. Em animais com psoríase, o tratamento (i.p.) com o GYY4137 reduziu (P<0,05) a inflamação cutânea (escores PASI) e o prurido, assim como inibiu o eixo NF-<font face = \"symbol\">k B-caspase-1-IL-1<font face = \"symbol\">b , e aumentou a atividade das enzimas antioxidantes (catalase, GST, GR e GPx). A pele de animais com psoríase exibiu menor capacidade na síntese de H2S, que foi paralela à menor expressão da enzima Cistationina-<font face = \"symbol\">b-sintetase (CBS). O bloqueador da enzima Cistationina-<font face = \"symbol\">g-liase (CSE) não interferiu no escore PASI ou prurido. Conclui-se que moléculas doadoras de H2S representam novos alvos terapêuticos no controle da inflamação aguda ou imunomediada associada à percepção de prurido agudo ou crônico. No microambiente inflamatório agudo, o mecanismo envolvido é independente da ativação de canais de KATP, enquanto no crônico (psoríase) é dependente, em parte, da inibição da ativação do eixo NF-<font face = \"symbol\">k B- caspase-1-IL-1<font face = \"symbol\">b e aumento das defesas antioxidantes. / Pruritus, like pain, is an aversive sensory experience associated with the scratching desire. Previous findings from this group demonstrated that hydrogen sulphide (H2S) donor molecules, a new endogenous mediator, when intra-dermal injected, reduced acute histamine and cutaneous inflammation induced by histamine or compound 48/80 (C48/80) on the dorsal skin of mice, suggesting the involvement of H2S in the control of amine-mediated pruritus. However, little is known about the mechanisms involved in the induction or inhibition of this sensorial perception (acute or chronic) and the participation of H2S. In order to get a better understanding, the objectives of this study were: i) to test and characterize the mechanisms involved in the protective effects of different H2S donors molecules (fast and slow release) on acute pruritus and associated inflammation induced by histamine dependent and independent stimuli; ii) to investigate the endogenous production of H2S and the enzymes involved in its synthesis in healthy and unhealthy/disease murine skin; and iii) to standardize a model of chronic pruritus associated with the psoriasis area severity index (PASI) in the inflamed skin, and to investigate the protective effect of a slow release H2S donor (GYY4137). The behaviour evaluation of acute pruritus and cutaneous inflammation (plasma extravasation, neutrophil influx) was performed alongside with different stimuli with or without the co-treatment (i.d.) with H2S donors in Balb/C mice. Experimental psoriasis was induced by topical application of imiquimod cream (IMQ 5%) on the dorsal skin, for 5 consecutive days, and at the same time, groups with the disease were treated intraperitoneally (i.p.) with GYY4137 at different doses (25 100 mg/kg). Records of pruritus and PASI were obtained during psoriasis induction, and biochemical and molecular analyses were performed at the end of the experiment. Firstly, treatment with increasing doses of GYY4137 (0.3 30 nmol/site, i.d.) inhibited acute pruritus induced by histamine or chloroquine and reduced the neutrophils influx induced by C48/80, without affecting histamine or C48/80 plasma-induced extravasation. Secondly, blocking the H2S-generating enzymes potentiated pruritus and the neutrophils influx triggered by C48/80. Pretreatment with glibenclamide (10 mg/kg; i.p., -30 min.), a KATP channel blocker, did not reverse the effect of the fast-release H2S donor on acute pruritus and inflammation induced by histamine. Finally, psoriatic animals, treated with GYY4137 (i.p.) showed a lower skin inflammation (PASI scores) and pruritus as well as the NF<font face = \"symbol\">kB-Caspase1-IL-1<font face = \"symbol\">b axis inhibited (P>0.05), and increased activity of antioxidant enzymes (catalase, GST, GR and GPx). The skin of psoriatic animals exhibited a lower capacity to synthetize H2S, which was parallel to expression of the enzyme Cystathionine-<font face = \"symbol\">b-synthetase (CBS). The Cystathionine-<font face = \"symbol\">g-lyase (CSE) enzyme blocker did not interfere with the PASI or pruritus score. We may conclude that H2S donor molecules represent new therapeutic targets to the control of acute or immune- mediated inflammation associated with the perception of acute or chronic pruritus. Also, in the acute inflammatory microenvironment, the mechanism involved is independent of KATP channels activation, whereas in the chronic condition it is partly dependent on the inhibition of NF-<font face = \"symbol\">kB-caspase-1-IL-1<font face = \"symbol\">b axis activation and increased antioxidants defence.

Made available in DSpace on 2014-12-17T15:42:26Z (GMT). No. of bitstreams: 1 ValdeliceRS.pdf: 981957 bytes, checksum: cedb4f2ae440069c889ba97e29744a20 (MD5) Previous issue date: 2007-07-11 / The natural gas (NG) is a clean energy source and found in the underground of porous rocks, associated or not to oil. Its basic composition includes methane, ethane, propane and other components, like carbon dioxide, nitrogen, hydrogen sulphide and water. H2S is one of the natural pollutants of the natural gas. It is considered critical concerning corrosion. Its presence depends on origin, as well as of the process used in the gas treatment. It can cause problems in the tubing materials and final applications of the NG. The Ag?ncia Nacional do Petr?leo sets out that the maximum concentration of H2S in the natural gas, originally national or imported, commercialized in Brazil must contain 10 -15 mg/cm3. In the Processing Units of Natural Gas, there are used different methods in the removal of H2S, for instance, adsorption towers filled with activated coal, zeolites and sulfatreat (solid, dry, granular and based on iron oxide). In this work, ion exchange resins were used as adsorbing materials. The resins were characterized by thermo gravimetric analysis, infrared spectroscopy and sweeping electronic microscopy. The adsorption tests were performed in a system linked to a gas-powered chromatograph. The present H2S in the exit of this system was monitored by a photometrical detector of pulsing flame. The electronic microscopy analyzes showed that the topography and morphology of the resins favor the adsorption process. Some characteristics were found such as, macro behavior, particles of variable sizes, spherical geometries, without the visualization of any pores in the surface. The infrared specters presented the main frequencies of vibration associated to the functional group of the amines and polymeric matrixes. When the resins are compared with sulfatreat, under the same experimental conditions, they showed a similar performance in retention times and adsorption capacities, making them competitive ones for the desulphurization process of the natural gas / O g?s natural (GN) ? uma fonte de energia limpa encontrada no subsolo de rochas porosas, associado ou n?o ao petr?leo. Sua composi??o b?sica inclui metano, etano, propano e outros componentes, como di?xido de carbono, nitrog?nio, ?cido sulf?drico e ?gua. H2S ? um dos poluentes naturais do g?s natural. ? considerado cr?tico no que se refere ? corros?o. Sua presen?a depende da origem, bem como do processo usado no tratamento do g?s. Ele pode acarretar problemas nas tubula??es e aplica??es finais do GN. A Ag?ncia Nacional de Petr?leo estabelece que a concentra??o m?xima de H2S no g?s natural, de origem nacional ou importado, comercializado no Brasil contenha no m?ximo 10 15 mg/m3. Nas Unidades de Processamento do G?s Natutal, diferentes m?todos s?o usados na remo??o de H2S, por exemplo, em torres de adsor??o recheadas com carv?o ativo, ze?litas e Sulfatreat (s?lido, seco, granular e baseado em ?xido de ferro). Neste trabalho, resinas de troca-i?nica foram usadas como material adsorvente. As resinas foram caracterizadas por an?lise termogravim?trica, espectroscopia de infravermelho e microscopia eletr?nica de varredura. Os ensaios de adsor??o foram realizados em um sistema acoplado a um cromat?grafo a g?s. O H2S presente na sa?da do sistema foi monitorado por um detector fotom?trico de chama pulsante. As an?lises de microscopia eletr?nica demonstraram que a topografia e morfologia das resinas favorecem o processo de adsor??o. Caracter?sticas como comportamento macro, part?culas de tamanhos variados, geometrias esf?ricas, sem a visualiza??o de poros na superf?cie, foram encontrados. Os espectros de infravermelho apresentaram as principais freq??ncias de vibra??o associadas aos grupos funcionais das aminas e matrizes polim?ricas. Quando comparadas ao sulfatreat, sob as mesmas condi??es experimentais, as resinas demonstraram semelhante desempenho em tempos de reten??o e capacidade de adsor??o, tornando-se competitiva para o processo de dessulfuriza??o do g?s natural

Made available in DSpace on 2014-12-17T15:42:27Z (GMT). No. of bitstreams: 1 ValdeliceRS.pdf: 629576 bytes, checksum: 6bcf4a0b805ce82618289068cfb23b77 (MD5) Previous issue date: 2006-07-11 / The natural gas (NG) is a clean energy source and found in the underground of porous rocks, associated or not to oil. Its basic composition includes methane, ethane, propane and other components, like carbon dioxide, nitrogen, hydrogen sulphide and water. H2S is one of the natural pollutants of the natural gas. It is considered critical concerning corrosion. Its presence depends on origin, as well as of the process used in the gas treatment. It can cause problems in the tubing materials and final applications of the NG. The Ag?ncia Nacional do Petr?leo sets out that the maximum concentration of H2S in the natural gas, originally national or imported, commercialized in Brazil must contain 10 -15 mg/cm3. In the Processing Units of Natural Gas, there are used different methods in the removal of H2S, for instance, adsorption towers filled with activated coal, zeolites and sulfatreat (solid, dry, granular and based on iron oxide). In this work, ion exchange resins were used as adsorbing materials. The resins were characterized by thermo gravimetric analysis, infrared spectroscopy and sweeping electronic microscopy. The adsorption tests were performed in a system linked to a gas-powered chromatograph. The present H2S in the exit of this system was monitored by a photometrical detector of pulsing flame. The electronic microscopy analyzes showed that the topography and morphology of the resins favor the adsorption process. Some characteristics were found such as, macro behavior, particles of variable sizes, spherical geometries, without the visualization of any pores in the surface. The infrared specters presented the main frequencies of vibration associated to the functional group of the amines and polymeric matrixes. When the resins are compared with sulfatreat, under the same experimental conditions, they showed a similar performance in retention times and adsorption capacities, making them competitive ones for the desulphurization process of the natural gas / O g?s natural (GN) ? uma fonte de energia limpa encontrada no subsolo de rochas porosas, associado ou n?o ao petr?leo. Sua composi??o b?sica inclui metano, etano, propano e outros componentes, como di?xido de carbono, nitrog?nio, ?cido sulf?drico e ?gua. H2S ? um dos poluentes naturais do g?s natural. ? considerado cr?tico no que se refere ? corros?o. Sua presen?a depende da origem, bem como do processo usado no tratamento do g?s. Ele pode acarretar problemas nas tubula??es e aplica??es finais do GN. A Ag?ncia Nacional de Petr?leo estabelece que a concentra??o m?xima de H2S no g?s natural, de origem nacional ou importado, comercializado no Brasil contenha no m?ximo 10 15 mg/m3. Nas Unidades de Processamento do G?s Natutal, diferentes m?todos s?o usados na remo??o de H2S, por exemplo, em torres de adsor??o recheadas com carv?o ativo, ze?litas e Sulfatreat (s?lido, seco, granular e baseado em ?xido de ferro). Neste trabalho, resinas de troca-i?nica foram usadas como material adsorvente. As resinas foram caracterizadas por an?lise termogravim?trica, espectroscopia de infravermelho e microscopia eletr?nica de varredura. Os ensaios de adsor??o foram realizados em um sistema acoplado a um cromat?grafo a g?s. O H2S presente na sa?da do sistema foi monitorado por um detector fotom?trico de chama pulsante. As an?lises de microscopia eletr?nica demonstraram que a topografia e morfologia das resinas favorecem o processo de adsor??o. Caracter?sticas como comportamento macro, part?culas de tamanhos variados, geometrias esf?ricas, sem a visualiza??o de poros na superf?cie, foram encontrados. Os espectros de infravermelho apresentaram as principais freq??ncias de vibra??o associadas aos grupos funcionais das aminas e matrizes polim?ricas. Quando comparadas ao sulfatreat, sob as mesmas condi??es experimentais, as resinas demonstraram semelhante desempenho em tempos de reten??o e capacidade de adsor??o, tornando-se competitiva para o processo de dessulfuriza??o do g?s natural

[Truncated abstract] Corrosion of steel structures caused by sulphide is a common engineering problem encountered by many industries, such as the petroleum, chemical processing, mining and mineral processing industries. The control of sulphide corrosion is still a controversial topic among corrosion engineers. There is an absence of guideline for a reliable acceptable limit of sulphide level in service and each processing industry has its own empirical values. Selection of inhibitors in the sulphide environment depends on laboratory testing before its actual application in pipelines and reaction vessels. Many investigators have postulated the corrosion mechanisms due to sulphide based on operating envelopes such as pH, chloride, manganese, hydrogen sulphide, sulphate reducing bacteria levels and inhibitor concentration. It is recommended in the literature that the batch dosing of inhibitor and biocide needs to be evaluated in regards to sulphide reducing bacteria (SRB) level, which may produce sulphide concentrations up to 2000 ppm. Although sulphide scale formation may protect the base metal by providing a physical barrier, the detrimental effects of sulphide are often inevitable, such as stress corrosion cracking, hydrogen embrittlement, etc. Currently, there are many chemicals that are used as inhibitors to prevent corrosion by scavenging the sulphide from the environment. Cerium, a rare-earth element, is not used as inhibitor in the sulphide environment. Also, there are no previous research findings on the effects of compounds of rare-earth metals, such as cerium chloride (CeCl3), in sulphide environment. This research examines the corrosion behaviour of 0.4Mo-0.8Cr steel, a High Strength Low Alloy (HSLA) steel, in sulphide-polluted artificial seawater with the addition of CeCl3 and glutaraldehyde. ... It is postulated that the moderate inhibiting effect of CeCl3 is due to the scavenging effect thereby forming Ce2S3 complex. Further reaction of sulphide with steel resulted in ferrous sulphide, leading to an increased corrosion rate. It is also concluded that the CeCl3 interferes with both anodic and cathodic reactions in deaerated conditions. Addition of glutaraldehyde in the sulphide-polluted seawater was found to decrease the corrosion rate. According to the electrochemical measurements conducted, the concurrent addition of glutaraldehyde and CeCl3 appeared to have an added effect on reducing the corrosion of the steel, as evidenced by the increase of the open circuit potential during the short-term testing. From the weight loss measurements after 60 days, sulphide pollution in deaerated seawater was found to increase corrosion rate. This is attributed to the increase of sulphide activity whereby continual dissolution of steel was encountered. From the weight loss tests, it was found that the addition of CeCl3 and glutaraldehyde reduced the corrosion rate of the steel in the solutions containing 0-10 ppm sulphide. There is no noticeable corrosion rate decrease for the solution containing 100 ppm sulphide. The added effect of CeCl3 and glutaraldehyde to the SRB medium has resulted in lower corrosion rates. Further detailed experimentation is required to elucidate the corrosion reduction mechanism in glutaraldehyde-containing environments.