La présence d'H2S dans un gisement est un important facteur de dévalorisation économique, c'est pourquoi connaitre sa concentration et sa distribution est capital pour optimiser toutes les étapes de l'exploration à la production d'un champ. Dans les conditions de pression et température des réservoirs, l'H2S est beaucoup plus soluble que les hydrocarbures et autres gaz. Le lessivage préférentiel de l'H2S par un aquifère actif pourrait ainsi entrainer la création d'hétérogénéités compositionnelles au cours du temps. L'objectif de la thèse est d'illustrer et quantifier ce processus à l'aide de simulations numériques réalisées avec Hytec, logiciel couplé géochimie-transport diphasique développé par MINES ParisTech. Le lessivage préférentiel de l'H2S est contrôlé par : la solubilité différentielle des gaz qui modifie les quantités relatives de chacun des gaz à proximité de l'aquifère ; le transport aqueux qui exporte les gaz dissous et améliore ainsi la dissolution des gaz sur le long terme ; le transport gazeux qui renouvelle les gaz dissous à l'interface et étend le lessivage du gaz à toute la structure ; les caractéristiques d'un réservoir (type d'aquifère, hétérogénéité des perméabilités).

Le sulfure d'hydrogène (H2S) est un métabolite bactérien produit notamment par les bactéries sulfato-réductrices du côlon à partir des acides aminés soufrés, des sulfates/sulfites alimentaires et des sulfomucines. A fortes concentrations, le H2S est un gaz toxique, de par sa capacité à inhiber la cytochome c oxydase, et par conséquent, la respiration mitochondriale. A l'inverse, notre travail montre qu'à faibles concentrations, le H2S induit une énergisation mitochondriale des cellules épithéliales coliques humaines HT 29 Glc-/+ lui conférant aussi un rôle de substrat minéral énergétique. Dans ce travail, nous avons déterminé les concentrations de H2S permettant l'oxydation/détoxication de H2S par les cellules HT 29 Glc-/+ et celles provoquant une inhibition de la consommation d'oxygène. L'oxydation du H2S nécessite la coopération entre la " sulfide oxidation unit " et la chaîne respiratoire. La capacité des cellules HT29 Glc-/+ à oxyder le H2S est associée à la présence des transcrits codant les enzymes constituant la " sulfide oxidation unit " : la sulfure d'hydrogène quinone reductase (SQR), la dioxygenase ETHE1 et la thiosulfate transferase (TST). Nous avons démontré la priorité de l'oxydation du H2S sur les substrats carbonés . En effet, nos résultats suggèrent que les électrons venant de la SQR sont transférés au pool d'ubiquinone aux dépens de ceux venant du complexe I. Nos résultats démontrent que la SQR joue un rôle déterminant pour l'oxydation de H2S. De plus, la détoxication du H2S par les cellules HT29 Glc-/+ augmente au cours de la différenciation spontanée ou induite par un traitement au butyrate. L'augmentation de la détoxication de H2S au cours de la différenciation est associée à une augmentation de la réserve respiratoire soulignant l'importance de la chaîne respiratoire comme composante de la fonction de détoxication du H2S. En situation d'inhibition de la cytochrome c oxydase, la grande capacité des cellules coliques humaines à détoxiquer le H2S pourrait être en partie due à la présence d'un transfert réverse des électrons issus de l'oxydation de H2S de la SQR vers le complexe I. Outre le butyrate, le zinc un autre composé de la lumière colique, exerce un effet protecteur contre la toxicité cellulaire du H2S. Enfin, notre travail a mis en évidence une diminution de l'expression d'un gène codant pour une enzyme de la " sulfide oxidation unit " (la TST) dans le rectum comparée à différents segments du côlon, ce qui pourrait correspondre à des capacités de détoxication du H2S différente en fonctions des segments du gros intestin humain.

ABSTRACT REMOVAL OF HYDROGEN SULFIDE BY REGENERABLE METAL OXIDE SORBENTS Karayilan, Dilek M.S., Department of Chemical Engineering Supervisor : Prof. Dr. Timur Dogu Co-Supervisor: Prof. Dr. G&uuml / lSen Dogu June 2004, 166 pages High-temperature desulfurization of coal-derived fuel gases is an essential process in advanced power generation technologies. It may be accomplished by using metal oxide sorbents. Among the sorbents investigated CuO sorbent has received considerable attention. However, CuO in uncombined form is readily reduced to copper by the H2 and CO contained in fuel gases which lowers the desulfurization efficiency. To improve the performance of CuO-based sorbents, they have been combined with other metal oxides, forming metal oxide sorbents. Sulfidation experiments were carried out at 627 oC using a gas mixture composed of 1 % H2S and 10 % H2 in helium. Sorbent regeneration was carried out in the same reactor on sulfided samples at 700 oC using 6 % O2 in N2. Total flow rate of gas mixture was kept at 100 ml/min in most of the experiments. In this study, Cu-Mn-O, Cu-Mn-V-O and Cu-V-O sorbents were developed by using complexation method. Performance of prepared sorbents were investigated in a fixed-bed quartz microreactor over six sulfidation/regeneration cycles. During six cycles, sulfur retention capacity of Cu-Mn-O decreased slightly from 0.152 to 0.128 (g S)/(g of Sorbent) while some decrease from 0.110 to 0.054 (g S)/(g of Sorbent) was observed with Cu-Mn-V-O. Cu-V-O showed a very good performance in the first sulfidation and excessive thermal sintering in the first regeneration prevented further testing. Sulfur retention capacity of Cu-V-O was calculated as 0.123 (g S)/(g of Sorbent) at the end of the first sulfidation. In addition, SO2 formation in sulfidation experiments was observed only with Cu-V-O sorbent.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / O aproveitamento do biogÃs e do gÃs natural (GN) com elevadas concentraÃÃes de diÃxido de carbono (CO2) e de sulfeto de hidrogÃnio (H2S), atravÃs de sistemas tÃrmicos de combustÃo convencionais, pode resultar em instabilidade de reaÃÃo ou, atÃ, apagamento da frente de chama, sob risco de avarias irreversÃveis para estrutura fÃsica dos equipamentos, devido aos Ãcidos corrosivos decorrentes da reaÃÃo. Ainda, altas concentraÃÃes desses contaminantes favorecem a ocorrÃncia de elevados Ãndices de gases poluentes nos produtos, a exemplo de monÃxido de carbono (CO) e hidrocarbonetos nÃo queimados (HC), dentre outros. Por essa razÃo, um estudo experimental foi realizado com base na aplicaÃÃo de uma tecnologia de combustÃo nÃo-convencional, a CombustÃo de FiltraÃÃo, a fim de lidar com esses combustÃveis de baixa qualidade. O aparato experimental empregado nessa pesquisa consiste de uma caldeira porosa de escoamento recÃproco, em que seu queimador à preenchido completamente por esferas cerÃmicas de alumina (Al2O3), formando uma matriz porosa inerte, que envolve os trocadores de calor da caldeira. O processo de queima de ambos os combustÃveis foi investigado sob condiÃÃes extremas de operaÃÃo, em termos de misturas ar-combustÃvel ultra-pobres. Como suporte para interpretaÃÃo dos fenÃmenos do processo, foi aplicado um modelo numÃrico de simulaÃÃo, que considera o mecanismo de oxidaÃÃo do metano em um meio poroso, adaptado para identificar os efeitos quÃmicos de uma alta concentraÃÃo de CO2 sobre a reaÃÃo. A influÃncia dos principais parÃmetros de operaÃÃo, razÃo de equivalÃncia e velocidade da mistura ar-combustÃvel, sob os produtos de combustÃo e sob a instabilidade de reaÃÃo foi estudada teÃrica e experimentalmente. Os resultados mostram excelente estabilidade operacional da caldeira com emissÃes ultra-baixas de CO e NOx, inferiores a 1 ppm para razÃes de equivalÃncia menores que 0,6, e com eficiÃncia de queima do H2S de mais de 99%. / The use of biogas and natural gas (GN) with high concentrations of carbon dioxide (CO2) and hydrogen sulfide (H2S) through conventional combustion thermal systems can result in reaction instability or flame front quenching, under risk of irreversible damages to the physical structure of a piece of equipments, due to corrosive acids remaining from reaction. Furthermore, high concentrations of these contaminants favor the occurrence of high pollutant levels in the products, like carbon monoxide (CO) and unburned hydrocarbon (HC), among others. Therefore, an experimental study was performed with basis on the application of a non conventional combustion technology, Filtration Combustion, in order to deal with these low-quality fuels. The experimental apparatus employed in this research consists of a reciprocal flow porous boiler, in which its burner is completely filled by ceramic spheres of alumina (Al2O3), forming an inert porous matrix, which involves boilerâs heat exchangers. The burning process of both the fuels was investigated under extreme operation conditions, in terms of ultra-lean fuel-air mixtures. As support for interpretation of the process phenomena, a numerical simulation model was applied, which takes in account the methane oxidation mechanism in a porous medium, adapted to identify the chemical effects of a high CO2-concentration on the reaction. The influence of the main operation parameters, equivalence ratio and gas flow velocity, on combustion products and on reaction stability was studied theoretically and experimentally. The results have shown excellent boiler operation stability with ultra-low emissions of NOx and CO, less than 1 ppm for equivalence ratios inferior to 0.6, and with the H2S-burning efficiency overcoming 99%.

Die vorliegende Arbeit befasst sich mit Untersuchungen zur Trockenentschwefelung von Brenngasen durch Partialoxidation von H2S an Herdofenkoks. Hierzu wurden Versuche in der Technikumsanlage VTE 2004 mit einem simulierten PHTW Gas durchgeführt. Es zeigte sich, dass der COS-Abbau nicht wie bisher angenommen durch die COS-Partialoxidation sondern durch die COS-Hydrolyse erfolgt. Die COS-Hydrolyse gewinnt dabei mit abnehmender Raumbelastung an Bedeutung. Der Entschwefelungsgrad erhöht sich mit steigendem Sauerstofffaktor und abnehmender Raumbelastung. Sauerstofffaktoren >4 sind aufgrund des vollständigen H2S-Umsatzes und der nicht ablaufenden COS-Partialoxidation nicht sinnvoll. Die Gewinnung des abgeschiedenen Schwefels auf dem Herdofenkoks konnte nachgewiesen werden. Abschließende Berechnungen ergaben, dass sich mit den erreichten Schwefelkonzentrationen im Reingas das Verfahren im aktuellen Entwicklungsstand für die Vorentschwefelung im IGCC-Kraftwerk eignet.

This study evaluated alternative sulfide treatment processes for potable water systems that rely on groundwater supplies. Research for this study was conducted at the Imperial Lakes (IL) and Turner Road (TR) water treatment plants (WTPs) in Polk County, Florida. These WTPs are in the process of refurbishment and expansion, and will require the installation of a new groundwater well. The IL and TR WTPs both rely upon groundwater sources that contain total sulfide at concentrations ranging from 1.4 to 2.6 mg/L. Sulfide is a concern because if left untreated it can impact finished water quality, corrosivity, create undesirable taste and odor, and oxidize to form visible turbidity. For this reason, the raw water will require treatment per Florida Department of Environmental Protection (FDEP) "Sulfide Rule" 62-555.315(5)(a). This rule does not allow the use of conventional tray aeration (currently in use at the IL and TR WTPs) for wells that have significant total sulfide content (0.6 to 3.0 mg/L). This research was commissioned because the potential water treatment method identified in the Sulfide Rule (i.e. forced-draft aeration) would not adequately fit within the confines of the existing sites and would pose undue burden to neighboring residents. In addition, an effective sulfide treatment process was desired that offered a low profile, did not necessitate the need for additional complex chemical feed systems, minimized the extent of electrical infrastructure upgrades, and was inexpensive to construct and operate. To meet these goals, several alternative technologies were evaluated at the desktop and bench-scale; these included anion exchange, various oxidation methods, and alternative media filtration processes. From that effort, several processes were selected for evaluation at the pilot scale: bleach (NaOCl) oxidation preceding electromedia filtration; manganese (IV) oxide (MnO2) filtration continuously regenerated with bleach; and ferrate (Fe(VI)) oxidation. Electromedia and MnO2 filtration were shown to be effective for total sulfide treatment. Both processes reduced total sulfide content to below detection levels ( > 0.1 mg/L) for groundwater supplies containing as much as 2.6 mg/L of total sulfide. The use of bleach oxidation ahead of media filtration also produced finished water with low turbidity ( > 1.0 NTU) as compared to conventional tray aeration and chlorination processes (6-16 NTU, as observed in this study). It was determined that the media filtration approach (electromedia and MnO2) was effective for sulfide treatment and met the County's site objectives established at the outset of the project. Ferrate was also shown to reduce total sulfide content to below detection levels ( > 0.1 mg/L) for groundwater supplies containing as much as 2.6 mg/L of total sulfide. An opinion of probable capital costs for installing a sulfide oxidation/filtration process at either the Imperial Lakes or Turner Road WTP was estimated to range from roughly $830,000 to $1,100,000. That equates to a $/kgal capital cost of $0.10 to $0.32 (at 8% for 20 years). An opinion of annual probable bleach chemical costs was estimated to range from $3,500 to $9,800 for the IL WTP and $3,500 to $5,800 for the TR WTP.

No description available.

H2S is a biologically relevant signaling gas that is endogenously produced throughout the body. The (patho)physiological roles of H2S have led researchers to develop various compounds that decompose to release H2S (H2S donors) for exogenous H2S administration. However, many small molecule H2S donors suffer from poor solubility, low stability, and lack of control over H2S release rates. As a result, there has been an increasing interest in utilizing supramolecular materials for exogenous H2S delivery. With growing potential applications of supramolecular H2S-releasing materials, it is important to explore their properties, e.g., solubility and stability under physiological conditions. We investigated the hydrolytic stability over a range of pH conditions of a series of peptides containing H2S-releasing S-aroylthiooximes (SATOs). The SATO-peptides showed structure–reactivity relationships with SATO ring substituents playing a crucial role in hydrolysis rates. Electron-donating substituents accelerate the rate of hydrolysis while electron-withdrawing substituents slows it down. We also explored their hydrolysis mechanisms at different pH values. SATO-peptides were then used to form hydrogels at 1 wt.% triggered by Ca2+. Hydrogels can be applied directly at a site of interest, potentially improving the efficacy of H2S compared with small molecule donors that diffuse away. We developed a H2S-releasing hydrogel capable of slowly releasing H2S locally to test its efficacy on intimal hyperplasia. The hydrogel delivered H2S over the period of several hours and inhibited the proliferation of human vascular smooth muscle cells (VSMCs) significantly better than fast-releasing NaSH salts. This study shows a promising application of supramolecular H2S-releasing materials over widely used sulfide salts. The macroscopic properties of peptide hydrogels could be further modulated to achieve additional control over the H2S release properties. We synthesized a series of peptide hydrogels incorporating different linker segments to study their effects on hydrogelation properties. Most peptides formed hydrogels but with significantly different rheological behavior. We found that peptides with flexible linkers such as ethyl, substituted O-methylene, and others, formed stronger hydrogels compared to those with more rigid linkers. Interestingly, we found that stiffer hydrogels released H2S over longer periods than softer ones by retarding the diffusion of a thiol trigger, likely due to bulk degradation of the soft gels but surface erosion of the stiff gels as they release H2S. / Doctor of Philosophy / H2S has long been known as a foul smelling gas until it was discovered that it is endogenously produced throughout the body and plays many (patho)physiological roles. Therapeutic benefits of H2S have led researchers to develop various compounds that release H2S (H2S donors) for exogenous H2S administration. However, many small molecule H2S donors suffer from poor solubility, low stability, and unregulated H2S release. As a result, there has been an increasing interest in utilizing materials for exogenous H2S delivery. With growing potential applications of H2S-releasing materials, it is important to explore their properties, e.g., solubility and stability under physiological conditions. We investigated the stability of a series of peptides containing H2S-releasing S-aroylthiooximes (SATOs) over a range of pH conditions. The stability of SATO-peptides was dependent on chemical makeup of the SATO part of the peptides. We also explored their hydrolysis mechanisms at different pH values. SATO-peptides were then used to form hydrogels triggered by Ca2+. Hydrogels can be applied directly at a site of interest, potentially improving the efficacy of H2S compared with small molecule donors that diffuse away. We developed a H2S-releasing hydrogel capable of slowly releasing H2S locally to test its efficacy on intimal hyperplasia. The hydrogel delivered H2S over the period of several hours and inhibited the proliferation of human vascular smooth muscle cells (VSMCs) significantly better than fast-releasing NaSH salts. This study shows a promising application of supramolecular H2S-releasing materials over widely used sulfide salts. The macroscopic properties of peptide hydrogels could be further modulated to achieve additional control over the H2S release properties. We synthesized a series of peptide hydrogels incorporating different linker segments to study their effects on hydrogelation properties. Most peptides formed weak to strong hydrogels with calcium chloride.We found that peptides with flexible linkers formed stronger hydrogels compared to those with more rigid linkers. Interestingly, we found that stiffer hydrogels released H2S over longer periods than softer ones.

Des observations macroscopiques et microscopiques sur les plantes actuelles et fossiles ont été effectuées. Sur les plantes actuelles ont été effectué des observations relativement aux effets des gaz volcaniques sur l’ultrastructure des cuticules de Pinus halepensis et de Erica arborea récoltés dans l’aire volcanique des Campi Flegrei, Italie. Les observations conduites au TEM sur les cuticules de P. halepensis, influencé et non influencé par les gaz volcaniques, ont montré que : 1) l'épaisseur totale de la CM (cuticule) + CW (paroi pectocellulosique) ne subit pas de variations significatives d'épaisseur ; 2) la cuticule des aiguilles influencée par les gaz volcaniques montre une accumulation d’oxalate de calcium ainsi que 3) un réarrangement des fibrilles disposées parallèlement à la surface. Les observations conduites sur E. arborea ont permis de 1) constater que les épaisseurs totales des cuticules, influencées ou non par les gaz, sont significativement différentes ; 2) en présence de gaz volcaniques la couche externe A2 subit un accroissement d’épaisseur significatif. Par rapport aux macro-restes végétaux fossiles, les localités du Crétacé de Cusano Mutri et Pietraroja ont été étudiées. Le première site fossilifère a permis 1) d’identifier plusieurs taxa appartenant aux conifères; 2) de décrire une nouvelle espèce de conifère: Frenelopsis cusanensis; 3) de trouver l’angiosperme ancestrale Montsechia vidalii. L’étude taxonomique a permis de décrire des entités typiques de la Province Euro-Sinienne. L’étude sédimentologique et systématique montre un climat plutôt tropical-subtropical, des abondants fusains montrant des incendies naturels. / Macroscopical and microscopical observations on extant and fossil plants have been made. Observations on extant plants led to study the effects of volcanic gases on the cuticle ultrastructure of Pinus halepensis and Erica arborea sampled in the volcanic area of Phlegrean Italy. TEM observations on P. halepensis cuticles fumigated or not by volcanic gases revealed: 1) insignificant thickness variations of the cell wall plus cuticle among current- and first-year-old needles of both fumigated and not fumigated trees; 2) a calcium oxalate accumulation in fumigated leaves; 3) moreover, in respect to the cell surface, fibrils are disposed parallel to the surface of the cuticle. In specimens of E. arborea fumigated or not by volcanic gases, 1) the total thickness of cuticles varies significantly; 2) in plants experiencing chronic fumigation the A2 layer increases its thickness. As for fossil plants, the cuticles of Cretaceous Fossil-Lagertätten of Cusano Mutri and Pietraroja have been studied. In the former: 1) numerous taxa belonging to conifers have been identified; 2) the new species Frenelopsis cusanensis has been described; 3) Montsechia vidalii has been found outside of Spain. Taxonomical studies allowed the description of typical Euro-Sinian fossil plants. Sedimentological and taxonomical studies suggest semi-arid or arid conditions in a subtropical or tropical climate. It is worth noting as for Cusano Mutri locality, evidence of wildfire (fusain) suggests a periodic combination of arid periods, high temperatures and lightning strikes.

Macroscopical and microscopical observations on extant and fossil plants have been made. Observations on extant plants led to study the effects of volcanic gases on the cuticle ultrastructure of Pinus halepensis and Erica arborea sampled in the volcanic area of Phlegrean Italy. TEM observations on P. halepensis cuticles fumigated or not by volcanic gases revealed: 1) insignificant thickness variations of the cell wall plus cuticle among current- and first-year-old needles of both fumigated and not fumigated trees; 2) a calcium oxalate accumulation in fumigated leaves; 3) moreover, in respect to the cell surface, fibrils are disposed parallel to the surface of the cuticle. In specimens of E. arborea fumigated or not by volcanic gases, 1) the total thickness of cuticles varies significantly; 2) in plants experiencing chronic fumigation the A2 layer increases its thickness. As for fossil plants, the cuticles of Cretaceous Fossil-Lagertätten of Cusano Mutri and Pietraroja have been studied. In the former: 1) numerous taxa belonging to conifers have been identified; 2) the new species Frenelopsis cusanensis has been described; 3) Montsechia vidalii has been found outside of Spain. Taxonomical studies allowed the description of typical Euro-Sinian fossil plants. Sedimentological and taxonomical studies suggest semi-arid or arid conditions in a subtropical or tropical climate. It is worth noting as for Cusano Mutri locality, evidence of wildfire (fusain) suggests a periodic combination of arid periods, high temperatures and lightning strikes.