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1
Karayilan, Dilek. "Removal Of Hydrogen Sulfide By Regenerable Metal Oxide Sorbents." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605046/index.pdf.
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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. GülSen 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.
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MacLachlan, Andrew. "Tuning morphology of hybrid organic/metal sulfide solar cells." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/25766.
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This thesis explores the influence that morphology plays in hybrid organic/inorganic solar cells. This is studied for a range of different materials systems. A series of cadmium xanthate complexes were synthesised, for use as in-situ precursors to CdS nanoparticles in hybrid poly(3-hexylthiophene-2,5-diyl (P3HT)/CdS solar cells. The heterojunction morphology of these hybrid P3HT/CdS blends was found to be dependent on the ligand moiety of the precursor used. The formation of CdS domains was studied by time-resolved materials characterisation techniques and directly imaged using electron microscopy. A combination of transient absorption spectroscopy (TAS) and photovoltaic device performance measurements was used to show the intricate balance required between charge photogeneration and having percolated domains in order to effectively extract charges to maximize device power conversion efficiencies. An analogous method was also applied to a P3HT/Sb_2 S_3 system. Following on from the previous work, a non-toxic alternative to CdS and Sb2S3 was explored. Bismuth xanthates were thermally decomposed to form hybrid polymer/Bi_2 S_3 heterojunctions with two distinctly different morphologies. The bismuth xanthates were found to form nanorods in-situ, within the solid-state polymer matrix, as well as mesostructured arrays of Bi_2 S_3 rods that were later infiltrated with a polymer, using a two-step method. TAS was used to study the charge generation yield in both these systems and hybrid photovoltaic devices were also fabricated. Finally, through a collaboration with The Institute of Photonic Sciences (ICFO), TAS was used to study two separate organic semiconductor/Bi_2 S_3 BHJs. The first of which was a P3HT/Bi_2 S_3 nanoparticle blend solar cell. The charge generation yield in this system was investigated and then compared to a novel thiol-functionalised P3HT based block copolymer (P3HT-SH). Secondly, TAS was used to obtain a better understanding of the charge transfer at several interfaces in a vertically structured Bi_2 S_3 nanorod array that was filled with 2,2',7,7'-Tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (SPIRO).
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Mbese, Johannes Zanoxolo. "Synthesis and characterization of metal sulfide nanoparticles/polymer nanocomposites." Thesis, University of Fort Hare, 2013. http://hdl.handle.net/10353/d1016190.
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The focus of this project was to synthesize and characterize metal sulfide nanoparticles /polymer nanocomposites. The work involved the synthesis of dithiocarbamato ligands and complexes derived from aniline. Zn(II), Cd(II) and Hg(II) dithiocarbamato complexes were used as single-molecule precursors for the synthesis of the ZnS, CdS and HgS nanoparticles and their optical and structural properties studied. The other focus of this work was to synthesize a combined functionality metal sulfide nanoparticles/polymer nanocomposites by dispersing as-synthesized ZnS, CdS and HgS nanoparticles in polymethyl methacrylate (PMMA) matrix. The characterization of the ligands, complexes, nanoparticles and nanocomposites were investigated using relevant instrumental tools like UV-Vis, photoluminescence (PL), Fourier transform infrared (FTIR), X-ray diffraction (XRD), energy dispersion X-ray (EDX), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
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Ramasamy, Karthik. "New molecular precursors for metal sulfides." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/new-molecular-precursors-for-metal-sulfides(49bcd8c0-4a37-4eb1-892e-7a7973f8f3cd).html.
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Metal sulfide thin films are important class of materials which have applications in photovoltaics, microelectronics and displays. Chemical vapour deposition (CVD) is well known method for the deposition of high quality thin films. Very few classes of single source precursors (eg: dithiocarbamates, xanthates) were successful for the deposition of good quality metal sulfide films by MOCVD. This limited choice was due to the difficulties of finding precursors with suitable physico-chemical properties. Hence, it is important to develop precursors with suitable volatility, solubility and being able to deposit films with little or no contamination. This work describes the synthesis of a series of metal (Fe, Co, Ni, Zn, Cd) complexes of thio- and dithio-biuret ligands, their structural and spectroscopic characterization and thermal decomposition. The complexes were used as single source precursors for the deposition of iron, cobalt, nickel, zinc, cadmium and zinc cadmium sulfide thin films by AACVD. The effect of alkyl groups, coordinating atoms, deposition temperatures on phases and morphology of the films were studied. The deposited films were characterised by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and atomic force microscopy (AFM). The complex [Fe(SON(CNiPr2)2)3] gave hexagonal troilite FeS films with small amount of tetragonal pyrrhotites Fe1-xS at 300 °C, whereas only troilite FeS was deposited at 350, 400 or 450 °C. Complexes [Fe2(µ-OMe)2 (SON(CNEt2)2)2] and [Fe(SON(CNEt2)2)3] deposited a mixture of hexagonal troilite FeS and cubic pyrite FeS2 films at all temperatures. [Fe(SON(CNMe2)2)3] deposited very thin films of FeS at all temperatures as troilite. Complexes [Co(N(SCNMe2)2)3] and [Co(N(SCNEt2)2)3] deposited hexagonal Co1-xS films at all temperatures of 350-500 °C, whereas [Co(SON(CNiPr2)2)2] gave mixture of cubic and hexagonal Co4S3 films at 280-400 °C. Thiobiuret complex [Ni(SON(CNMe2)2)2] gave orthorhombic Ni7S6. Complexes [Ni(SON(CNMe2CNEt2))2] and [Ni(SON(CNEt2)2)2] gave mixtures of hexagonal Ni17S18 and orthorhombic Ni7S6. In contrast, [Ni(SON(CNiPr2)2)2] gave orthorhombic Ni9S8. Dithiobiuret complexes [Ni(N(SCNMe2SCNEt2))2] and [Ni(N(SCNEt2)2)2] gave hexagonal NiS1.03 at 360 and 400 °C, orthorhombic Ni7S6 phase at 440 and 480 °C. The zinc complexes [Zn(N(SCNMe2)2)2] and [Zn(SON(CNiPr2)2)2] deposited cubic ZnS at 300 and 350 °C, whereas at 400 and 450 °C hexagonal ZnS were apparent [Zn(N(SCNEt2)2)2] gave hexagonal ZnS films at all deposition temperatures. Cadmium complexes [Cd(N(SCNMe2)2)2], [Cd(N(SCNEt2)2)2] and [Cd(SON(CNiPr2)2)2] gave hexagonal CdS films at all deposition temperatures.
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Aldemir, Müge. "Metal oxide supported cadmium sulfide for photocatalytic synthesis of homoallylamines." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=978677617.
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Charron, Luc G. "Radiative properties of molybdenum sulfide and other transition metal dichalcogenides." Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/26599.
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Low temperature radiative properties of the layered transition metal dichalcogenides 2H-MoS2, 2H-WS2 and 2H-WSe 2 are investigated. Synthetically grown crystals of all three materials, natural 2H-MoS2 single crystals and several 2H-MoS2 and 2H-WS2 commercial powders are studied. Steady-state photoluminescence (PL) measurements performed on the samples reveal two distinct radiative regions in the near infrared. The first region consisting of several sharp lines is produced by bound excitons related to the halogen transport agent intercalated within the van der Waals gap of the layered compounds. The second weaker region, composed of a broad spectral band, originates from the radiative recombination between an intrinsic crystal lattice defect center and the valence band in the conditions of a strong electron-phonon coupling. Time decay analysis of the bound excitonic radiative transitions is performed with time-resolved and PL intensity ratio measurements. The spectral and temperature dependence of the total radiative emissions of all three compounds are described in the framework of a two-channel kinetic recombination model in thermal equilibrium conditions. A configuration coordinate diagram is also constructed for 2H-MoS 2. PL intensity measurements performed on the 2H-MoS2 and 2H-WS2 synthetic crystals reveal a sublinear PL dependence on excitation intensity. Finally a technique developed to intercalate halogen molecules in natural 2H-MoS2 single crystals is described.
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Janyasuthiwong, Suthee. "Biogenic sulfide production at low pH and selected metal precipitation for e-waste leachate treatment." Thesis, Paris Est, 2015. http://www.theses.fr/2015PEST1056/document.
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La contamination métallique dans l'environnement est l'un des problèmes mondiaux persistants car non seulement elle perturbe la qualité de l'environnement, mais aussi l'environnement et la santé humaine. La principale contribution à ce problème se pose principalement des activités anthropiques telles que les industries. La rareté de métal est devenu plus sévère récents où certains éléments ont été prédit pour être pleinement éradiquée depuis plusieurs décennies de la croûte terrestre. Récemment, des chercheurs ont concentré leur attention pour récupérer ces métaux dans le flux des déchets et de la réutiliser dans les processus de production industrielle. L'utilisation des déchets agricoles comme adsorbant potentiel à faible coût pour l'enlèvement des métaux lourds des eaux usées est une des technologies les plus polyvalents. Dans cette étude entre les différents adsorbants testés, coquille d'arachide établi rendements d'épuration élevés avec moins d'exigences pour un traitement ultérieur de poste pour le Cu, Pb et Zn retrait. En outre, les expériences de lots sur les principaux effets des paramètres du procédé (pH, adsorbant dosage, temps de contact et de la concentration initiale de métal) ont montré un effet majeur sur l'absorption des métaux et de l'efficacité de l'enlèvement. Pour la régénération matériau, HCl 0.2 M était la solution de désorption la plus efficace qui ne altère pas l'efficacité, jusqu'à trois cycles d'adsorption et de désorption. L'utilisation de bactéries réductrices de sulfate (SRB) dans des bioréacteurs est une autre technologie qui peut être appliqué pour le traitement de métal contaminé les eaux usées. Le SRB réduire le sulfate en sulfure, qui réagit en outre avec des métaux pour former des précipités de sulfures métalliques. Le lit fluidisé (IFB) bioréacteur inverse est la configuration qui présente la proéminence en utilisant la technologie de SRB pour le traitement des eaux usées métalliques contaminés. Deux bioréacteurs IFB ont été opérés à différents pH (7.0 et 5.0). L'activité de SRB à pH 7.0 était plus élevée qu'à un pH de 5.0, ce qui montre que le pH est le principal facteur qui affecte SRB. Cependant, le thiosulfate a montré une efficacité supérieure à celle du sulfate en tant qu'accepteur d'électrons alternatif. Le sulfure produit en utilisant du thiosulfate comme accepteur d'électrons était 157.0 mg / L, tandis que seulement 150.2 mg / L a été produit en utilisant du sulfate et il a fallu une période d'adaptation à un pH de 5.0 avant la réussite de l'opération. En outre, l'IFB a montré sa grande efficacité pour le Cu, Ni et Zn élimination des eaux usées synthétique. L'élimination de Cu et Zn étaient plus de 90% à pH 7.0 et 5.0, à une concentration initiale de métal de 25 mg / L. D'autre part, l'élimination de Ni ne était pas éliminé à une concentration initiale de 25 mg / L comme il a montré des effets toxiques à l'égard SRB. Il existe différents types de flux de déchets contaminés par des métaux qui se présentent comme un bon candidat pour la récupération des métaux comprennent e-déchets. Cet e-déchets a un fort potentiel en tant que source secondaire de métal pour récupérer les métaux en particulier base tels que Cu, Ni et Zn. Cartes de circuits imprimés (PCB) d'ordinateurs personnels ont été évalués comme source secondaire potentielle de Cu, Ni et Zn en utilisant des méthodes de précipitation hydrométallurgiques et de sulfure. Les conditions optimales pour la lixiviation des métaux étaient de 0.1 M HNO3 avec un rapport liquide solide de 20 à l'aide de PCB de 0.5 - taille des particules de 1.0 mm à 60 ° C qui a abouti à 400 mg Cu / g PCB. Avec la précipitation de sulfure à un rapport stoechiométrique de 1: 1 (Cu: S2-), la récupération de Cu a été très efficace jusqu'à 90% de la solution de lixiviation a représenté à environ 0.41 g Cu / g BPC, tout en Ni et Zn étaient récupération 40 % et 50% pour les lixiviats d'une colonne à courant ascendant de lixiviation, respectivementMetal contamination in the environment is one of the persisting global issues since it not only disturbs the environmental quality but also the environment and human health. The major contribution to this problem arises mainly from anthropogenic activities such as industries. Metal scarcity has become more severe lately where some elements have been predicted to be fully eradicated in several decades from the earth crust. Recently, researchers have focused their attention to recover these metals from the waste stream and reuse it in industrial production processes. The use of agricultural wastes as a potential low cost adsorbent for heavy metal removal from wastewater is one of the most versatile technologies. In this study among the different adsorbents tested, groundnut shell established high removal efficiencies with fewer requirements for further post treatment for Cu, Pb and Zn removal. Furthermore, the batch experiments on the main effects of process parameters (pH, adsorbent dosage, contact time and initial metal concentration) showed a major effect on metal uptake and removal efficiency. For material regeneration, 0.2 M HCl was the most effective desorbing solution that did not alter the efficiency, up to three cycles of adsorption and desorption. The use of sulfate reducing bacteria (SRB) in bioreactors is another technology that can be applied for the treatment of metal contaminated wastewater. The SRB reduce sulfate into sulfide which further reacts with metals to form metal sulfide precipitates. The inverse fluidized bed (IFB) bioreactor is the configuration which shows prominence in utilizing SRB technology for metal contaminated wastewater treatment. Two IFB bioreactors were operated at different pH (7.0 and 5.0). The sulfate reducing activity (SRA) at pH 7.0 was higher than at pH 5.0, which shows that pH is the main factor that affects SRA. However, thiosulfate showed a higher efficiency than sulfate as an alternate electron acceptor. The sulfide produced using thiosulfate as the electron acceptor was 157.0 mg/L, while only 150.2 mg/L was produced using sulfate and it required an adaptation period at pH 5.0 prior to successful operation. Moreover, the IFB had shown its high efficiency for Cu, Ni and Zn removal from synthetic wastewater. The removal of Cu and Zn were more than 90% at pH 7.0 and 5.0, at an initial metal concentration of 25 mg/L. On the other hand, Ni removal was not removed at an initial concentration of 25 mg/L as it showed toxic effects toward SRB. There are various types of metal contaminated waste streams which pose as a good candidate for metal recovery include electronics waste (e-waste). This e-waste has a high potential as secondary source of metal to recover especially base metals such as Cu, Ni and Zn. Printed circuit boards (PCBs) of personal computers were evaluated as the potential secondary source of Cu, Ni and Zn using hydrometallurgical and sulfide precipitation methods. The optimal conditions for metal leaching were 0.1 M HNO3 with a liquid to solid ratio of 20 using PCBs of 0.5 - 1.0 mm particle size at 60 °C which resulted in 400 mg Cu/g PCBs. With sulfide precipitation at a stochiometric ratio of 1:1 (Cu:S2-), the recovery of Cu was very effective up to 90% from the leachate which accounted to approximately 0.41 g Cu/g PCBs, while Ni and Zn recovery were 40% (0.005 g Ni/g PCBs) and 50% (0.006 g Zn/g PCBs) for leachate from an upflow leaching column, respectively. This indicates Cu can be recovered from PCBs using sulfide precipitation
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LI, Bihong. "EFFECTS OF METAL AND METAL SULFIDE INCORPORATION ON PORPHYRIN AND RUTHENIUM DYE SENSITIZED SOLAR CELLS." Miami University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1484141398978806.
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Arancon, Rick Arneil. "Exploration of Transition Metal Sulfide Catalysts Prepared by Controlled Surface Chemistry." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEN063.
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L'hydrotraitement est un procédé catalytique important dans le raffinage du pétrole qui utilise des catalyseurs bimétalliques sulfurés NiWS ou NiMoS (ou CoMoS) supportés sur alumine. Leur mode conventionnel de préparation implique l’imprégnation d'une solution aqueuse de sels de Mo/W et de Ni/Co, puis l’activation par un agent sulfo-réducteur (H2S/H2). Pour répondre aux exigences environnementales et améliorer l'efficacité de l'hydrotraitement, des améliorations permanentes de la performance de ces systèmes catalytiques sont attendues. Ce travail se concentre sur la préparation de catalyseurs d'hydrotraitement hautement actifs par une approche de chimie de surface contrôlée (CSC) qui implique l'imprégnation successive de précurseurs moléculaires de MoV et NiII en solvant organique sur un support silice-alumine traité thermiquement. Dans la première partie de cette thèse, la genèse de la phase active du catalyseur CSC et conventionnel Mo et NiMo est étudiée par quick-XAS combinée à d’autres techniques (chimiométrie, XPS, RPE, STEM-HAADF, modélisation moléculaire). Nous proposons ainsi des structures moléculaires depuis les précurseurs oxydes de Mo et Ni supportés jusqu’aux nombreuses espèces intermédiaires (oxysulfure et sulfures) en fonction de la température. Cette analyse multi-technique permet d'abord de révéler les spécificités de la genèse des catalyseurs CSC et conventionnels qui peuvent expliquer leurs différentes activités catalytiques. Ensuite, elle révèle également de nouvelles connaissances sur les mécanismes d’insertion du Ni dans la phase NiMoS en fonction de la préparation. Dans la seconde partie, la possibilité de remplacer Co et Ni comme promoteurs est explorée. Ceci est entrepris en synthétisant des catalyseurs alternatifs de type XYMoS, où X et Y sont des métaux de transition 3d. Comme suggéré par des études de modélisation quantiques antérieures, certaines formulations XYMoS peuvent présenter un effet de synergie analogue à ceux des phases actives CoMoS et NiMoS. L’étude des formulations les plus prometteuses méritent d'être approfondies afin de mieux comprendre leur fonctionnementHydrotreating is an important catalytic process in petroleum refining which uses sulfided bimetallic catalysts NiWS or NiMoS (or CoMoS) supported on alumina. Their conventional preparation involves an incipient wetness impregnation of an aqueous solution of Mo/W and Ni/Co salts, and then activation by a sulfo-reductive agent (such as H2S/H2). To meet environmental regulations and improve the energy efficiency of hydrotreatment, permanent improvements on the performance of these catalytic systems are expected. This work is thus focused on the preparation of highly active hydrotreating catalysts through a controlled surface chemistry (CSC) approach; which involves the successive impregnation of Mo5+ and Ni2+ molecular precursors in an organic solvent on a thermally treated silica-alumina support. In the first part of this thesis, the active phase genesis of CSC and conventional Mo and NiMo catalysts is studied by in situ quick-XAS combined with various other techniques (chemometrics, XPS, EPR, STEM-HAADF, molecular modeling). We thus propose molecular structures from the oxide of supported Mo and Ni precursors up to the numerous intermediate sulfided species as a function of temperature. This multi-technique analysis enables first to reveal the specific features of the genesis of CSC and conventional catalysts which may explain their different catalytic activities. Then, it also reveals new insights into the mechanisms of Ni promoter incorporation into the NiMoS phase as a function of the preparation. In the second part, the feasibility of replacing Co and Ni as promoters is explored. Using the CSC method, we attempted to synthesize alternative catalysts of the form XYMoS ternary sulfides, where X and Y are 3d transition metals. As suggested by previous quantum simulations, certain XY formulations possibly reveal a synergy effect as observed in CoMoS and NiMoS active phases. The most promising formulations merit further investigations
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Shi, Zhengqi. "Development of Metal Sulfide Semiconductor Light Absorbers for Solar Cell Application." University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1525474936984221.
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Laurenzi, Laura. "Investigating metal attenuation processes in mixed sulfide carbonate bearing waste rock." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/58165.
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The objective of this study was to identify the trace metal/secondary mineral phase associations in a heterogeneous waste rock dump that contains carbonate bearing lithologies and a mix of metal sulfides. The identification of attenuation processes can be used to better predict the drainage chemistry from waste rock at this site and/or other sites with similar waste rock. This study also provides the opportunity to investigate metal attenuation at the largest scale of complexity and compare these observations to those made from the smaller scale tests conducted for this site and is useful for understanding scalability of the smaller scale tests. This study shows that in carbonate bearing waste rock the predominant processes that attenuate copper (Cu) and zinc (Zn) are precipitation of hydroxycarbonate and hydroxysulfate phases and sorption onto iron oxides. Arsenic (As) and molybdenum (Mo) are associated with iron oxides, although for Mo this association was observed in only a few samples. Lead (Pb) was observed in association with iron oxides. Wulfenite observed in a few samples provides an additional attenuation process for Mo and Pb. The stability of the phases and potential for remobilization of these metals can also be suggested from this study. The hydroxycarbonate/hydroxysulfate phases are the least stable phases identified and can dissolve at pH<5. Iron oxides are considered a stable phase, as such, the As, Cu, Pb and Zn associated with these phases may also be quite stable. Sorption of Mo is limited at neutral pH but wulfenite is a stable phase that is not expected to dissolve once formed. Geochemical modelling of seepages from the dump show that iron oxides are supersaturated and wulfenite and gypsum are at equilibrium. Two mixed Cu:Zn hydroxycarbonate phases and hydrozincite were added to the geochemical database and are supersaturated, while malachite and smithsonite were generally undersaturated. Brochantite and antlerite were also generally undersaturated, but the observations made in this study show that copper hydroxysulfates and mixed copper/zinc hydroxysulfates are precipitating. In mixed sulfide/carbonate bearing waste rock mixed of Cu:Zn hydroxycarbonate and hydroxysulfate phases may require consideration for adequate prediction of Cu and Zn concentrations in drainage.Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate
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Ji, Yijie. "Metal Organic Frameworks Derived Nickel Sulfide/Graphene Composite for Lithium-Sulfur Batteries." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron152233332526446.
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Africa, Cindy-Jade. "Investigation of microbial metal-sulfide interfacial environments under mineral bioleach simulated conditions." Doctoral thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/25001.
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This research pertains to bioleaching of copper containing ores with particular reference to the copper sulfide mineral chalcopyrite (CuFeS2). While it is focused on heap bioleaching, it has applications to stirred tank bioleaching operations. In the context of bioleaching, microbial extra-cellular polymeric substance (EPS) components are thought to complex chemical oxidants and extend the chemical reaction space available for mineral dissolution reactions, making the microbial-mineral-EPS interface the dominant active zone in terms of microbial oxidation and mineral dissolution. There is a limited understanding of microbial biofilm formation within a bioleach heap. The implication of various microorganisms having a set of defined or optimal conditions under which they colonise and proliferate is quite substantial. Understanding what creates favourable interfacial microenvironments enabling a sessile population to flourish (and thereby decrease lag time) has great implications for minimising costs and maximising productivity. Furthermore, limited work has been conducted on thermophilic microorganisms relevant to bioleaching. These microorganisms are pertinent to successful bioleaching at high temperatures, with work incorporating low grade ores and gangue mineralogy also being scarce. The aim of this research is to provide a thorough investigation into microbial-metal sulfide interfacial environments in situ, using a thermophilic archaeon M. hakonensis, low-grade metal-sulfide ores, a series of temperature regimes, heap-simulating conditions and an in depth extraction and analysis of the EPS produced under varied culturing conditions.
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Leclerc, Marlène Déborah. "Cosmochemistry of iron meteorites : trace element composition of metal and sulfide phases." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/40429.
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Trace elements composition of the metal and sulfide phases in iron meteorites have been studied in 42 iron meteorites and 2 pallasites. 19 iron meteorites thick sections containing sulfide inclusions have been mapped and their mineralogy, texture and major and minor element compositions analyzed by SEM and EPMA and their trace elements composition measured using LA-ICP-MS. A highly homogeneous fragment of Cape York troilite has been found suitable to be used as a sulfide standard for moderately volatile elements in LA-ICP-MS analysis. A further 34 sulfide samples were digested in ultrapure acids and analyzed by Solution-ICP-MS. In thick sections, the iron meteorites Dronino, Nantan and Patos de Minas showed a rim of Ni and Co-rich sulfides around troilite (FeS) nodules, they are terrestrial weathering products of the troilite. X-RD analysis produced the characteristic pattern for pentlandite ((Fe,Ni)9S8) and heazlewoodite (Ni3S2). Analysis of powder from a sulfide nodule of Uruaçu also showed presence of magnetite (Fe3O4) and goethite (FeO(OH)), infilling cracks within the troilite nodule. Terres- trial weathering and shock-melting are found not to affect the moderately volatile trace elements content of the sulfide, except for Ni and Co that are enriched by terrestrial weathering. Bulk iron meteorite compositions have been calculated from LA-ICP-MS and Solution-ICP-MS measurements. They show a depletion of moderately volatile elements (condensing between 1350 and 650 degrees K) and the strongly volatiles Cd and In. The depletion is greater for IVA irons. IABs, IIABs, IIIABs and pallasites have similar levels of depletion which are greater than what has been observed for ordinary chondrites. The selenium content of the sulfide is inversely correlated with bulk Ni content and the bulk selenium vs. bulk sulfur content show loss of a sulfide liquid from the IIIAB and IVA parent-body but not from the IAB group which lies on the CI line.
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Kim, Changsu. "Optical, laser spectroscopic, and electrical characterization of transition metal doped ZnSe and ZnS nano- and microcrystals." Birmingham, Ala. : University of Alabama at Birmingham, 2009. https://www.mhsl.uab.edu/dt/2009r/kim.pdf.
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Thesis (Ph. D.)--University of Alabama at Birmingham, 2009.Title from PDF title page (viewed Feb. 3, 2010). Additional advisors: Renato Camata, Derrick Dean, Chris M. Lawson, Andrei Stanishevsky, Sergey Vyazovkin. Includes bibliographical references (p. 133-140).
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Alghamdi, Yousef Gamaan A. "N-methyl-N’, N’-dimethylethylene-/-propylene-diaminodithiocarbamato-metal complexes as single source precursors for metal sulfide semiconductors materials." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/nmethyln-ndimethylethylenepropylenediaminodithiocarbamatometal-complexes-as-single-source-precursors-for-metal-sulfide-semiconductors-materials(4a7b739b-0f61-4610-a149-c79a7c09b4d4).html.
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A series of N-methyl-N’,N’-dimethylethylene-/-propylene-diaminodithiocarbamato-metal complexes [M(S2CN(Me)(CH2)nN(Me)2)2] (M = Zn, Cd, Cu, Ni; n = 2 or 3), [M(S2CN(Me)(CH2)nN(Me)2)3] (M = Co, In; n = 2 or 3), [M(S2CN(Me)(CH2)nN(Me)2)] (M = Ag; n = 3) has been synthesized and characterised by microelemental analysis, NMR (1H, 13C), IR and some by X-ray crystallography. X-ray single crystal structures for [M(S2CN(Me)(CH2)nN(Me)2)2] (M = Zn, Cd, n = 2 or 3) and [M(S2CN(Me)(CH2)nN(Me)2)3] (M = In; n = 2 or 3) have been determined. Zinc and cadmium structures are polymers. All polymerise through the nitrogen of dimethylamino group to the metal atoms. Both indium structures are monomers where each indium is bonded with six sulphur atoms from three bidentate dithiocarbamato ligands.All twelve metal complexes were solids and stable to air and moisture for periods of several months hence potentially useful as single source precursor for metal sulfide thin films. Metal sulfide thin films including zinc sulfide, cadmium sulfide, copper sulfide, nickel sulfide, cobalt sulfide, indium sulfide, copper indium sulfide, silver indium sulfide, and cadmium zinc sulfide were deposited by aerosol assisted chemical vapour deposition (AACVD) method. Deposition from each precursor was carried out at three different (300, 400 and 500 °C) temperatures to investigate the effect of deposition temperature on the size and shape of crystallites as well as phase of the material. All deposited films were characterized by powder X-ray diffraction (p-XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and atomic force microscopy (AFM). Mostly good quality, adhesive and specular thin films of these materials were obtained. p-XRD showed significant changes in the phase of materials depending upon the growth temperature. SEM and AFM images showed the morphology of the films was strongly linked to the deposition temperature. This is the first systematic study on N-methyl-N’,N’-dimethylethylene-/-propylene-diaminodithiocarbamatometal complexes and their use as single source precursors for the metal sulfide thin films.
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ALLEN, JEFFREY W. "METAL RECOVERY AND REUSE: TREATMENT OPTIONS FOR THE BERKELY PIT." University of Cincinnati / OhioLINK, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin974471224.
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McMahon, Jennifer Nicole. "Heavy metal competition for acid volatile sulfide binding sites in southeastern coastal sediments." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/19134.
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Morris, Robert Eugene. "THE CONTROL OF SULFUR EMISSIONS DURING THE ROASTING OF METAL SULFIDES (LIME, ZINC)." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275396.
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Hartle, Matthew. "Binding of Hydrogen Sulfide to biologically relevant scaffolds: Metal systems and non-covalent binding." Thesis, University of Oregon, 2017. http://hdl.handle.net/1794/22278.
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Hydrogen Sulfide (H2S) is an important biologically produced gasotransmitter along with carbon monoxide (CO) and nitric oxide (NO). Unlike CO and NO, the bioinorganic chemistry of H2S reactivity with biologically relevant metal centers remains underinvestigated. To address this gap, several model bio(in)organic complexes were used to understand the ligation and reaction chemistry of H2S, including phthalocyanine, protoporphyrin IX, tetraphenyl porphyrin, and a pyridine diimine zinc complex. In addition to being a reactive gasotransmitter, the hydrosulfide anion (HS–) has been found to be an important biological anion.
Studies with readily available cobalt and zinc phthalocyanines in organic solution illustrated the importance of protonation state in the ligation and redox chemistry of H2S and highlighted the need for an organic-soluble source of HS–. To address this need, we developed a simple method to prepare tetrabutylammonium hydrosulfide (NBu4SH). Using NBu4SH, we expanded the knowledge of H2S reaction chemistry to encompass a significantly larger set of biologically relevant metals beyond iron using the protoporphyrin IX scaffold, revealing three principle reaction pathways: binding, no response, or reduction and binding.
Iron in biology is of particular importance given its role in oxygen transport in hemoglobin. The swamp-dwelling bivalve L. Pectinata hemoglobin 1 (Hb1) transports H2S, via ligation to heme, to symbiotic bacteria. The stabilization of H2S in Hb1 is believed to be from one of the following: a protected pocket, hydrogen bonding with a proximal glutamate residue, or a complex combination of these or other factors. By using Collman's "Picket-Fence" porphyrin to isolate the protected pocket model, we determined that a protected pocket alone as insufficient to account for H2S stabilization on Hb1. This realization led to an examination of hydrogen bonding in the secondary coordination sphere of a zinc complex.
Finally, we explored the role of HS– as a biologically relevant anion using a bis(ethynylaniline) supramolecular receptor. We determined that rather than covalently modifying the receptor molecule, HS– was bound in the pocket, similar to bacterial anion transport channel.
This dissertation includes previously published co-authored material.
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Sweeney, Jason T. (Jason Thomas) 1971. "Novel metal oxide nanocomposites for oxygen storage, sulfur dioxide adsorption and hydrogen sulfide absorption." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/29295.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, February 2003.Includes bibliographical references.
Increasingly stringent regulations on automotive emissions have resulted in the need for improved pollution control technology. To reduce mobile emissions, researchers have investigated alternatives such as lean-bum engines and fuel cells. This work is focused on the synthesis, characterization and testing of novel metal oxide nanocomposites to facilitate the utilization of these technologies. In lean-bum engines, the use of adsorbents to remove NOx faces two major challenges: (1) excess hydrocarbon and CO emissions during fuel-rich pulses for adsorbent regeneration, and (2) reduced NOx adsorption efficiencies due to competitive adsorption of SO2 in the gas stream. To provide for the low-temperature oxidation of hydrocarbons and CO under a reducing atmosphere, CeO2, a well-known oxygen storage material, was modified through secondary metal oxide doping to improve thermal stability and oxygen accessibility. 20 at% substitution of Pr, Sc and Zr in CeO2 successfully promoted microstructural stability, with Ceo.8Zro0.202- retaining grain size of 30 nm even after calcination at 10000C. At high doping levels, Zr improved grain size stability further, but ZrO2 phase segregation was noted in CelxZrxO2.8 with x > 0.2. TPR experiments under 2.5% H2 in He showed that Ceo8Pr0.202- provided superior low-temperature reduction and overall reducibility amongst Ce0.8M0.2026- materials. Moreover, CelxPrxO2-8 showed increased reducibility with increasing x, achieving a maximum weight loss of 4.8% at x = 1.0. CO oxidation studies over Ceo.8M0.202-8 identified Sc and Zr doping with the lowest CO light-off temperatures (247⁰C and 264⁰C, respectively).
(cont.) For CelPrxO2- and CelxZrxO2-, low levels of doping resulted in the highest CO oxidation activity; light-off was successfully achieved at 264⁰C and 252⁰C for x = 0.4 and 0. 1, respectively. Metal oxide-based materials were developed to selectively adsorb SO2 during fuel-lean conditions and desorb SO2 during fuel-rich conditions, thereby preventing the SO2 poisoning of the NOX adsorbent. Of various simple and mixed metal oxides, the Cr203-CuO system was found to provide SO2 adsorption under oxidizing conditions at 400⁰C, and SO2 evolution under reducing conditions below 350⁰C. The CuCr20O4 phase present at the optimal Cr20O3-CuO composition gave rise to improved low-temperature CO activity, which facilitated SO2 desorption. With increased CuO content, both adsorption capacity and regenerability were increased. Through the introduction of dopants, phase-pure CuCr2yCoyO4 was obtained to allow for SO2 desorption below 300Ê»C, which corresponded well with increased CO2 evolution. By introducing excess CuO onto CuCr1.9Co0.1O4 via various synthesis routes, improved SO2 sorption characteristics were attained. In pulse adsorption/desorption studies, the CuO/ CuCr.9Co0.104 materials and CuO/CuCr204 also demonstrated excellent capacity and superior regenerability relative to the conventional CuO/A1203 adsorbent. For on-board H2 production for fuel cells, the removal of H2S is paramount to avoiding poisoning of the H2 separation membrane and the fuel cell. Conventional coarse-grained ZnO is not viable for H2S ...
by Jason T. Sweeney.
Ph.D.
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Spraggins, Jeffrey M. "Environmental applications of ESI FT-ICR mass spectrometry oxidized peptides and metal sulfide clusters /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 231 p, 2010. http://proquest.umi.com/pqdweb?did=1993336521&sid=11&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Roffey, A. R. "Dithiocarbamate complexes as single source precursors to metal sulfide nanoparticles for applications in catalysis." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1437012/.
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Herein we report the solvothermal decomposition of a range of metal dithiocarbamate complexes for the synthesis of metal sulfide nanoparticles. Metal sulfides exist in a variety of structural phases, some of which are known to be catalytically active towards various processes. The aim of this work was to synthesise a variety of different metal sulfide phases for future catalysis testing, particularly the iron sulfide greigite (Fe3S4, a thiospinel containing Fe2+ and Fe3+) which is to be tested for CO2 reduction. A range of metal dithiocarbamate complexes were synthesised and Chapter 2 focusses on the synthesis of iron dithiocarbamates. Both iron(II) and iron(III) complexes were synthesised, the latter being a facile, open bench reaction producing a range of [Fe(S2CNRR’)3] complexes. Iron(II) bis(dithiocarbamates) are extremely air sensitive therefore carbonyl protected [Fe(S2CNRR’)2(CO)2] complexes were prepared for ease of use as precursors. The stability of the complexes was tested by TGA to ensure they were suitable precursors for metal sulfide synthesis, i.e. that the carbonyl ligands were sufficiently labile to leave the complexes before decomposition, which proved to be successful. In the following Chapter these iron dithiocarbamate complexes were solvothermally decomposed, but interestingly a combination of iron(II) and iron(III) precursors did not produce greigite as expected, but pyrrhotite (Fe7S8, containing only Fe2+). Systematic studies into the effect of decomposition temperature, precursor concentration and precursor type, on the phase and morphology of the resulting iron sulfide nanoparticles were performed on the iron(III) dithiocarbamate precursor. The phase was found to be highly dependent on both concentration and temperature. The use of a redox active additive, thiuram disulfide, on the decomposition was also investigated and found to have a significant effect, promoting the formation of the metastable greigite phase. Chapter 4 examines the nickel bis(dithiocarbamate) decomposition system to see if its behaviour was consistent with trends observed in the iron case. In general, similar trends were observed in the phase and morphology of the nickel sulfides when the decomposition parameters were varied, metastable phases were observed at lower temperature and higher concentration. The effect of thiuram disulfide on the system was greater, however, than in the iron case, whereby an additional nickel sulfide phase (NiS2) was observed at high concentration in the presence of this additive. Chapter 5 deals with a broader range of metal dithiocarbamate systems, to attempt to elucidate whether or not the trends seen for nickel and iron are universal for metal dithiocarbamate precursors. The Co, Cu, Zn and In dithiocarbamate systems were examined with and without thiuram disulfide, and some effect were seen on the phase of metal sulfide nanoparticle formed, but only at high concentration in the presence of the additive. Mixed-metal studies were performed to investigate the suitability of metal dithiocarbamates as precursors to ternary metal sulfides, and success was observed for iron-nickel, cobalt-nickel and iron-copper sulfides, though the iron-zinc and iron-indium systems only produced binary sulfides. The final Chapter looks into the metal dithiocarbamate decomposition mechanism in detail, using [Ni(S2CNiBu2)2] as a model system. NMR, in situ UV-vis, MS and powder XRD are all employed to probe the mechanism, in conjunction with XAS and computer modelling which was performed by others. The mechanism was found to rely heavily on an intermediate formed from amide exchange between the dithiocarbamate backbone and solvent amine, indicating the solvent plays an extremely significant role in the solvothermal synthesis of metal sulfides from dithiocarbamate precursors.
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Chiloane, M. H. "Thin film deposition of metal sulfide and metal oxide layers with and without polymer intercalation by using chemical bath deposition technique." Thesis, Vaal University of Technology, 2017. http://hdl.handle.net/10352/388.
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A well adherent single layer thin film of zinc oxide (ZnO), zinc sulfide (ZnS), cadmium oxide (CdO) and cadmium sulfide (CdS) has been deposited on silica glass substrates from basic baths containing zinc acetate, cadmium acetate, ammonium hydroxide, triethanolamine, thiourea, and sodium hydroxide as precursors by chemical bath deposition (CBD), followed by multilayer deposition of metal oxide/metal sulfide and metal sulfide/metal oxide then intercalated by polyvinyl alcohol (PVA). CBD was used for the deposition of the metal sulfide/oxide thin films under acidic and basic conditions for single layer thin film by varying temperature and pH. SEM micrograph of the as-deposited ZnS, ZnO, CdO, and CdS thin film, show the film to be uniform, dense, homogeneous at lower temperatures and composed of large irregular shaped grains that are scattered at higher temperatures. These large grains are comprised of smaller spherical grains. Star shapes were observed for ZnO and ZnS thin films while spherical shapes were observed for CdO and CdS thin films.
The effect of temperature on the optical properties was studied by varying the deposited films at different temperatures of 60˚C, 70˚C, and 90˚C. The increase in temperature on the single layer depositions caused the decrease in %T which was in support with the large SEM results which in higher absorbance. Films of different thickness of (114.4 nm, 107.7 nm, 100.4 nm, and 99.67 nm) respectively were obtained for single layer deposition. The XRD study of the ZnS, ZnO, CdO, and CdS monolayer films deposited does not reveal any well-defined peak, indicating a highly disordered material. The XRD of CdO thin films showed one broad peak around 2θ value 26.37° corresponding to (111) plane. The structural studies had similar behavior of CdS, ZnO, and ZnS was similar with CdO with one broad peak at 2θ ~ 26˚.
To enhance the property of MO, MS thin film was formed on the interfaces of MO thin film as a passivation and a substrate layer at 60°C with a pH value of 11 for 60 minutes deposition time and vice versa for enhancing the property of MS. The structural, morphological and optical properties of CBD deposited thin films have been studied by varying the processing parameters and the MO/MS multilayer ratio of the starting
v
precursors to provide a better understanding of the growth conditions by studying the MO/MS and MS/MO multilayer thin film materials with further intercalation of polyvinyl alcohol (PVA). Multilayer thin films show different physical properties other than the conventional monolayer thin films. The films were deposited as the matrix of MO/MS and MS/MO of respectively at temperatures of 60˚C at alkaline medium for 60 minutes deposition time. SEM micrograph of CdO/CdS was observed to be spherical shapes which show the film to be uniform, dense, and homogeneous. Large spherical particles that appear to be increasing in size and non-homogeneous were observed in the deposition of CdS/CdO. The deposited ZnO/ZnS thin films show large conglomerate of snowflake structures and that of ZnS/ZnO thin film were polycrystalline in structure. The optical properties and band-gap energy were studied by depositing the films at 60˚C for 60 minutes.
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More, Andrew P. "Textural and microstructural studies of zinc sulfide and associated phases in certain base metal deposits." Thesis, Aston University, 1988. http://publications.aston.ac.uk/14382/.
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A textural and microstructural study of a variety of zinc sulfide-containing ores has been undertaken, and the possible depositional and deformational controls of textural and microstructural development considered. Samples for the study were taken from both deformed and undeformed zinc ores of the Central U.S. Appalachians, and deformed zinc ores of the English Pennines. A variety of mineralogical techniques were employed, including transmitted and reflected light microscopy of etched and unetched material, transmission electron microscopy and electron microprobe analysis. For the Pennine zinc sulfides, spectroscopic, x-ray diffraction and fluid inclusion studies were also undertaken. Optical and electron optical examination of the Appalachian material confirmed the suitability of zinc sulfide for detailed study with such techniques. Growth and deformation-related microstructures could be distinguished from specimen-preparation induced artifacts. A deformationally-mduced lamelliform optical anisotropy is seen to be developed in areas hosting a dense planar microstructure of {111} twin- and slip-planes. The Pennine zinc sulfide texturally records a changing depositional environment. Thus, for example, delicately growth- zoned crystals are truncated and cross-cut by solution disconformities. Fluid inclusion studies indicate a highly saline (20-25 wt. % equiv. NaCl), low temperature (100-150°C.) fluid. Texturally, two varieties of zinc sulfide can be recognised; a widely developed, iron- banded variety, and a paragenetically early variety, banded due to horizons rich in crystal defects and microscopic inclusions. The zinc sulfide takes the form of a disordered 3C-polytype, with much of the disorder being deformational in origin. Twin- and slip-plane fabrics are developed . A deformation-related optical anisotropy is seen to overprint growth-related anisotropy, along with cuprian alteration of certain {111} deformation planes.
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ZHANG, JIE. "INVESTIGATIONS OF OXIDE AND SULFIDE BASED LOW DIMENSIONAL NANO STRUCTURES FOR CONDUCTOMETRIC GAS SENSORS, MEMRISTORS AND PHOTODETECTORS." OpenSIUC, 2015. https://opensiuc.lib.siu.edu/dissertations/1086.
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Low dimensional semiconductors are promising materials with diverse range of applications in a variety of fields. Specifically, in recent times low dimensional oxide and sulfide based semiconductors are regarded as materials that can have potential applications in chemical gas sensor, optoelectronic devices and memristor. How ever, in some cases it is envisioned that appropriate doping as well as phase stabilization is important in enhancing their material properties. This work presents the synthesis, characterization and application of various (pristine and doped) quasi-one dimensional metal oxides (TiO2, VO2) and two-dimensional materials (CuO thin film, MoS2). Some practical protocols for stabilization of specific phases at ambient conditions via a new method of doping in VO2 nanostructures with aluminum, is demonstrated. Similarly, a temperature-doping level phase diagram for the free-standing nanostructures in the temperature range close to the ambient conditions was presented. TiO2 nanowire was doped during growth and electrical measurements on individual TiO2 single crystal nanowires indicate that light in visible range can induce electron-hole pair formation. Furthermore, gas sensing (CO, H2) measurements taken under visible light irradiation imply that photo-activated chemical oxidization on the surface of TiO2 nanowires occurs, which is responsible for the observed measurements. Further, the effect of self heating in some nanostructures was also explored. Since self-heating is a prospective power-efficient energy delivery channel to the conductometric chemical sensors that require elevated temperatures for their operation, the unprecedentedly low power consumption can be achieved via minimizing the heat dissipation in the optimized device architecture. By investigating the heat dissipation in these devices we show that the thermal, electrical and chemical properties of the self-heated semiconducting nanowires appear to be strongly coupled with each other at nanoscale. This opens up unique opportunity to fabricate low power nanoscopic sensing leading to an ultra-small and power efficient single nanostructure gas recognition system. The CuO film based lateral devices were fabricated and studied for its resistive switching behavior. A good, stable and reproducible threshold RS performance of CuO film was obtained by electrical measurement. Finally, the micro-flake MoS2 based FET photoelectronic device was fabricated (using mechanically exfoliated MoS2) and its electronic and photoelectronic properties were investigated. We show that though the FET mobility values of MoS2 microflake is in the average range, but the photo-responsivity is much higher compared to most of others similar sulfide based 2D layered materials.
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Korehi, Hananeh [Verfasser]. "Microbial diversity in mine tailings and the role of metal sulfide oxidizers in biomining processes / Hananeh Korehi." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2015. http://d-nb.info/1071669192/34.
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Grant, Hannah [Verfasser]. "Trace and critical metal behaviour in seafloor massive sulfide deposits: A mineralogical and geochemical assessment / Hannah Grant." Kiel : Universitätsbibliothek Kiel, 2019. http://d-nb.info/1189137526/34.
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Svahn, Joacim. "Metal release and mobility in an arctic lake due to artificial drainage : Effects of mining and sulfide oxidation." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-58306.
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The aim of this report was to investigate the potential effects of sulfide oxidation in sediments of an arctic lake, N Luossajärvi, induced by lowered water level. Lake water, potentially contaminated by metals, was pumped into a mine tailings impoundment. The water quality in the receiving water was evaluated to see if the drainage have had an effect on the water quality. Six sediment profiles were sampled. Each profile were divided into 5 cm sections and analyzed for major elements and trace metals. Water chemistry were analyzed at six sites. As, Ni and Cu had high concentrations within undrained sediments, where As levels were classified as highly contaminated (> 27 mg kg-1 dw). Trace metals had strong statistical correlation to each other indicating a common source. The PCA analyzes performed suggests that trace metals are controlled by a common factor and drained sediments showed two additional factors controlling the variance of metals. Water chemistry had overall good status, but As, Cd, Ni and Cu exceeded natural background values. Historical data on the other hand showed no statistical difference from measured values. No effects on water quality could therefore be seen after draining of the lake, proposing high precipitation of metals within the tailing or that metals is still prevailing in the drained sediments. Metal mobility were seen within the drained sediments, where only As and Cd were presumed connected to chemical weathering and where erosion and soil properties seems to be responsible for most metal mobility.
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Hardardóttir, Vigdís. "Metal-rich Scales in the Reykjanes Geothermal System, SW Iceland: Sulfide Minerals in a Seawater-dominated Hydrothermal Environment." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19925.
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Downhole sampling of unboiled liquid at 1350 and 1500 m depth in the seawater-dominated Reykjanes high-temperature geothermal system in Iceland shows that metal concentrations measured at surface are minimum values due to mineral precipitation in the wells; by analogy of similar tectonic setting, host rocks and fluid composition, the metal concentrations measured in many black smoker vents at the seafloor are also minima. Fluids in the Reykjanes geothermal system react with mid-ocean ridge basalt at temperatures as high as 346°C and contain Fe 9-140 ppm, Cu 14-17 ppm, Zn 5-27 ppm, Pb 120-290 ppb, 1-6 ppb Au, and 28-107 ppb Ag. Fluids discharged at surface from the same wells have orders of magnitude lower metal concentrations due to precipitation caused by boiling and vapor loss during depressurization. Upstream of the orifice plate at high pressure (40 bar, 252°C) the precipitates consist mainly of sphalerite and chalcopyrite with a trace of galena and bornite. At the orifice plate of old wells, the pressure decreased sharply to 11 bar (188°C), resulting in abundant deposition of amorphous silica together with minor sphalerite and traces of chalcopyrite. In new wells the pressure at the orifice plate decreases to 22 bar (220°C); this pressure decrease and concomitant boiling causes deposition of fine-grained bornite-digenite solid solution together with sphalerite and galena on the fluid flow control valve. In high-pressure wells (average wellhead pressure 45-35 bar) most metals (mainly as sphalerite) are deposited downstream of the orifice plate, with up to 950 ppm Au and 2.5 wt.% Ag. Bulk concentrations in the scales vary between 15-60 wt.% upstream and downstream of the orifice plate and diminish from there. Iron increases up well from 8 to ~20 wt.% and decreases downstream of the orifice plate from 6 to 2 wt.% at the separation station; Cu downhole is ~3 wt.% but increases to 25 wt.% on the fluid flow control valve and then decreases; Pb downhole 100s ppm but at the wellhead is ~3 wt.%, increasing to 15 wt.% at the fluid flow control valve, then decreasing sharply from there.
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Cooke, Sharon A. "Alternative chalcogen sources for the growth of cadmium sulfide and cadmium selenide by metal organic chemical vapour deposition." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284186.
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Lima, Daniel David de. "AvaliaÃÃo da remoÃÃo de metais pesados em efluentes industriais por sulfeto quÃmico e biogÃnico." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=10570.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoO presente estudo teve o objetivo de avaliar a remoÃÃo de metais pesados em efluentes industriais pelo uso de sulfeto quÃmico e biogÃnico. Inicialmente, foi operado, sob condiÃÃes mesofÃlicas (27  2 ÂC), um reator anaerÃbio de manta de lodo e fluxo ascendente (VÃtil = 2,7 L; TDH = 24 h) suplementado com sulfato (em relaÃÃes DQO/SO42- de aproximadamente 10 e 5) para a produÃÃo de sulfeto biogÃnico. Posteriormente, o efluente das indÃstrias de folheaÃÃo de joias da cidade de Juazeiro do Norte, CearÃ, foi caracterizado para verificar os principais metais contidos e suas faixas de concentraÃÃes, alÃm de outros constituintes. Em seguida, analisou-se a aplicaÃÃo de planejamento experimental multivariado cujos fatores estudados foram concentraÃÃo de metal (20, 80 e 140 mg/L), concentraÃÃo de sulfeto (20, 40 e 60 mg/L) e tempo de reaÃÃo (1, 5 e 9 min), no processo de remoÃÃo dos metais cobre, zinco e nÃquel, tanto na presenÃa quanto na ausÃncia de macro e micronutrientes. Finalmente, foi verificada em experimentos univariacionais a influÃncia das condiÃÃes operacionais tempo de reaÃÃo (15 e 30 min), razÃo molar metal/sulfeto (0,5; 0,7; 1; 1,6; 1,75 e 2) e fonte de sulfeto (quÃmico e biogÃnico) na eficiÃncia de remoÃÃo dos metais pesados analisados. ApÃs a caracterizaÃÃo do efluente das indÃstrias de folheaÃÃo de joias constatou-se que os metais majoritÃrios foram cobre, nÃquel e zinco. O reator sulfetogÃnico apresentou operaÃÃo estÃvel para as relaÃÃes DQO/SO42- estudadas, com remoÃÃo de DQO superior a 70% e reduÃÃo de sulfato acima de 90%. A partir do planejamento experimental multivariado, observou-se que o fator mais significativo foi a concentraÃÃo de metal para todos os casos, sendo que, para o cobre, a concentraÃÃo de sulfeto nÃo teve efeito significativo na presenÃa de macro e micronutrientes. Por sua vez, para o nÃquel, constatou-se que todos os fatores exercem influÃncia sobre a eficiÃncia de remoÃÃo. Jà para o zinco, o tempo nÃo teve influÃncia significativa na ausÃncia de macro e micronutrientes, enquanto que na presenÃa dos mesmos tal variÃvel apresentou significÃncia. Em seguida, nos experimentos univariacionais verificou-se que o tempo de reaÃÃo nÃo influenciou a remoÃÃo de metais estudados. A fonte de sulfeto apresentou efeitos diversos assim como a relaÃÃo molar metal/sulfeto. Por exemplo, com o cobre, em razÃes molares metal/sulfeto menores que 1,6, foram obtidas as maiores diferenÃas na eficiÃncia de remoÃÃo chegando atà 70%. Jà para o zinco, sà foram observadas algumas diferenÃas para razÃes molares acima de 1,6. Finalmente, para o nÃquel, alguma diferenÃa sà foi verificada para razÃes de atà 1.
The present study aimed to assess heavy metals removal from industrial effluents by using chemical and biogenic sulfide. Initially, an upflow anaerobic sludge blanket reactor (working volume = 2.7 L, HRT = 24 h), supplemented with sulfate (COD/SO42- ratio of approximately 10 and 5), was operated under mesophilic conditions (27 Â 2 ÂC) for biogenic sulfide production. Subsequently, the effluent of jewelry plating industries from the city of Juazeiro do Norte, CearÃ, was characterized in order to verify the major metals and their concentration ranges, as well as other constituents. Then, the application of a multivariate experimental design, whose factors were metal concentration (20, 80 and 140 mg/L), sulfide concentration (20, 40 and 60 mg/L) and reaction time (1, 5 and 9 min), in the process of copper, zinc and nickel removal, both in the presence and absence of macro and micronutrients, was analyzed. Finally, in univariate experiments, the influence of the operating conditions, such as reaction time (15 and 30 min), metal/sulfide molar ratio (0.5, 0.7, 1, 1.6, 1.75 and 2) and sulfide source (chemical and biogenic), on the removal efficiency of the tested heavy metals was verified. After the characterization of the jewelry plating industries effluent, it was found that the majority metals were copper, nickel and zinc. The sulfidogenic reactor showed stable operation for the COD/SO42- ratios studied, with COD removal higher than 70% and sulfate reduction above 90%. From the multivariate experimental design, the most significant factor was metal concentration in all cases. For copper, sulfide concentration had no significant effect in the presence of macro and micronutrients. However, for nickel, all the factors have an influence on removal efficiency. And, for zinc, the time had no significant influence in the absence of macro and micronutrients, whereas, in their presence, that variable was significant. From the response surface contour plot, the optimum point, in terms of removal efficiency, obtained for nickel in the presence and absence of macro and micronutrients was [Ni2+] = 140 mg/L, [S2-] = 60 mg/L and t = 1 min. Subsequently, in the univariate experiments, it was found that the reaction time did not affect the removal of metals studied. The sulfide source had different effects as well as the metal/sulfide molar ratio. For example, for copper, at metal/sulfide molar ratios lower than 1.6, the greatest differences in removal efficiency were obtained, which reached up to 70%. However, for zinc, some differences were only observed at molar ratios above 1.6. Finally, for nickel, differences were observed for molar ratios below 1.
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Vitor, Ribeiro De Sá. "3D geostatistical modeling and integration of lithology, physical properties and element contents for characterizing metal deposit in a seafloor hydrothermal vent area." Kyoto University, 2020. http://hdl.handle.net/2433/254523.
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Blomkvist, Bella. "Temporal and spatial trends of heavy metal leakage from acid sulfate soils : Leakage of Ni, Zn, Cu and Fe to freshwater and marine sediments, North-eastern Sweden." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-174837.
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Acid Sulfate soils (AS) are recognized for being a source of acidity in freshwaters in America, Europe, Australia, and Asia. Apart from the problematic acid leachate, AS soil serves as a possible source of toxic heavy metals in freshwaters, a problem which has received far less attention than problems related to acid leachate. This study assessed to what extent heavy metals enriched in sediments from the area around lake Persöfjärden (North-eastern Sweden) could be attributed to export from AS soils. I found that: i) Nickel (Ni), Zink (Zn), Copper (Cu) and Iron (Fe) in the sediments had a partial likely origin from AS soils; ii) vertical variations in Ni, Zn, Cu and Fe concentrations suggested events of increased metal transport in the past; and iii) there is a tendency that Zn and Ni assumed from AS soils have caused elevated metal concentration in marine sediment deposited in Persöfjärden. Inferred sediment rates suggest that elevated metal concentrations occurred in sediment deposited during the 18-19th and 20th century. I argue that these periods correspond to periods of increased drainage of the AS soils during past agricultural activities in the catchment.
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Liu, Haiyan. "Synthesis and Kinetic Studies of High-Valent Metal-Oxo Species Generated by Photochemical and Chemical Methods." TopSCHOLAR®, 2018. https://digitalcommons.wku.edu/theses/2803.
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Highly reactive iron-oxo intermediates play important roles as active oxidants in enzymatic and synthetic catalytic oxidation. Many transition metal catalysts are designed for biomimetic studies of the predominant oxidation catalysts in Nature, namely cytochrome P450 enzymes. In this work, a series of iron(IV)-oxo porphyrins [FeIV(Por)O] and manganese(IV)-oxo porphyrins [MnIV(Por)O] have been successfully produced in two electron-deficient ligands by photochemical and chemical methods, and spectroscopically characterized by UV-vis, and 1H-NMR.
With iodobenzene diacetate [PhI(OAc)2] as the oxygen source, iron(III) porphyrin and manganese(III) porphyrin complexes converted to the corresponding metal(IV)-oxo species as oxygen atom transfer (OAT) agents. In addition, a new photochemical method was developed to generate the same species by visible light irradiation of highly photo-labile porphyrin-iron(III) bromate or porphyrin-manganese(III) chlorate precursors. Furthermore, the kinetics of oxygen transfer atom reactions with alkene, active hydrocarbons and aryl sulfides by photo-generated and chemical-generated [FeIV(Por)O]were studied in CH3CN solutions. Apparent second-order rate constants determined under pseudo-first-order conditions for sulfide oxidation reactions are (9.8 ± 0.1) × 102 − (3.7 ± 0.3) × 101 M-1s-1, which are 3 to 4 orders of magnitude greater in comparison with those of alkene epoxidations and activated C-H bond oxidations by the same oxo species.
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Gjønnes, Anders Welde. "Effect of Sulfide Inclusions in Austenitic Stainless Steel on the Initiation of Pitting in Base Metal and Heat Affected Zone after Welding." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19594.
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The predominant site for the initiation of pitting on austenitic stainless steel has been shown to be sulfide inclusions and notably the manganese types of sulfides. Dissolution of inclusions has been observed and suggested to be the initial step for pit initiation, though several explanations for the mechanisms causing initiation has been proposed. Regarding welded stainless steels, several microstructural changes have been described and suggested to contribute to the decreased corrosion resistance in the weld zone. An area which has not been investigated much is the contribution of inclusions, in particular MnS inclusions, to the reduced corrosion resistance and the initiation of pitting in the weld zone. In the present work a literature review of the investigations focusing on the initiation of pitting by sulfide inclusions in austenitic stainless steels has been provided. A literature review of investigations focusing on the effects of welding on the microstructure, inclusions and the corrosion properties in the weld zone of austenitic stainless steels has also been provided.Experimental work was performed to obtain results which could be compared to or verify findings and suggestions from the reviewed literature regarding the initiation of pitting by inclusions. Observations of MnS inclusions as the preferential site for pit initiation in austenitic stainless steel was tried recreated. The hypothesis saying that dissolution of MnS inclusions occur prior to the initiation of pitting was also tried verified. It was also performed experiments to obtain results which could give knowledge about the effects of MnS inclusions on the corrosion properties and the initiation of pitting in the weld zone of an austenitic stainless steel. Along with this, the corrosion behaviour and microstructural changes in the weld zone in general and compared with the base metal were studied. A part of the work was also to study the effect of a lacking inert shielding gas during welding.Samples of a 316L stainless steel were first examined in SEM to study the microstructure and to identify inclusions. Then, some samples were welded, followed by SEM examination. Then all samples were polarized electrochemically in synthetic seawater with the purpose of initiating pitting. After the polarization, all samples were examined in SEM again to correlate pitting attack to inclusions and to compare microstructural changes and the corrosion behaviour in the base metal and the weld zone.It was verified that the main initiation site for pitting in the base metal was MnS inclusions. It was indicated that dissolution of the MnS inclusions started the pit initiation process, with the contribution of released compounds from the inclusions. An average percent of inclusions showing an inactive behavior regarding the initiation of pitting was 38 %, verifying similar observations reported in earlier investigations. A nitric acid treatment to remove MnS inclusions improved the pitting resistance significantly.The welding caused the initiation of corrosion at lower potentials when performing electrochemical polarization in synthetic seawater. The corrosion mechanism was probably grain boundary corrosion caused by precipitation of chromium carbides in the grain boundaries. A lacking inert shielding gas during welding did not have any effect on the potential for the initiation of corrosion when comparing two samples welded with and without shielding gas.It was indicated that compositional changes had occurred for MnS inclusions in a certain distance from the fusion line. These changes may have caused the inclusions to be more prone to initiate pitting. Further investigation should be performed to clarify the behaviour of such inclusions, and their susceptibility towards the initiation of corrosion. Grain boundary corrosion in various grades had occurred in the HAZ in certain distances from the fusion line. In a further distance from the fusion line pitting-like corrosion in clusters, possibly induced by chromium depletion after forming chromium oxides combined with a thin oxide film, had occurred. The grain boundary corrosion and the pitting cluster attack are from the experimental results believed to be more important for the failure of the welded stainless steel investigated in this work, than pitting initiated at MnS inclusions changed by the welding process.
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Ghabel, Vahid Reza. "Design and Development of a Novel Remediation Process for Metal Production From Berkeley Pit Acid Mine Drainage." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1194966560.
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Ghavami-Riabi, Reza. "Geochemical exploration for base metal sulphide deposits in an arid environment (eastern Namaqua Metamorphic Province), South Africa." Thesis, Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-06192007-100552.
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Lohmayer, Regina [Verfasser], and Britta [Akademischer Betreuer] Planer-Friedrich. "Importance of Sulfide, Polysulfides, and Elemental Sulfur for Abiotic and Biotic Redox Processes in Sulfur-Metal(loid)Systems / Regina Lohmayer. Betreuer: Britta Planer-Friedrich." Bayreuth : Universität Bayreuth, 2015. http://d-nb.info/1080237569/34.
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Schachtl, Eva Christina [Verfasser], Johannes A. [Akademischer Betreuer] Lercher, and Tom [Akademischer Betreuer] Nilges. "Mechanistic studies of reactions of polyaromatic compounds on metal sulfide catalysts / Eva Christina Schachtl. Betreuer: Johannes A. Lercher. Gutachter: Johannes A. Lercher ; Tom Nilges." München : Universitätsbibliothek der TU München, 2015. http://d-nb.info/1081488115/34.
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Brion, Jean-Marc. "Contribution à l'étude des mécanismes de formation de couches de transfert non métalliques sur un outil en coupe continue d'aciers de décolletage a inclusions contrôlées." Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL043N.
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On présente l'étude des mécanismes de formation des couches de transfert sélectif (CTS) de sulfures de manganèse sur un outil de coupe a partir des seules inclusions contenues de façon contrôlée dans l'acier usiné. On montre que la stabilité de la CTS sur l'outil correspond à un équilibre dynamique entre sa vitesse d'alimentation et sa vitesse d'érosion avec l'adhérence inclusion/outil comme mécanisme clé gouvernant cette stabilité. Cette adhérence est liée à l'affinité chimique entre l'élément métallique actif présent à la surface de l'outil (Zr, ti) et le soufre des inclusions de l'acier exprimée en termes d'enthalpie de formation du sulfure correspondant. Par spectroscopie des électrons Auger en mode balayage, nous avons réussi à comprendre le mécanisme le plus probable d'accrochage des sulfures de manganèse sur des outils mixtes composes de carbures WC et tic. A l'endroit des carbures simples de type wc, on assiste a une usure diffusionnelle classique qui se traduit par leur dissociation et évacuation continuelles. En revanche, l'élément de transition (ti) dans les carbures actifs également dissociés forme, avec les inclusions de l'acier usine, une fine couche d'oxysulfure stable, et certainement adhérente, qui interrompt cette dissociation et constitue une base d'accrochage pour d'autres sulfures. Dans la même logique, on constate que la continuité chimique du compose actif à la surface de l'outil (outils revêtus) favorise encore la stabilité des CTS. Bien que d'importance cruciale, la maitrise compositionnelle de la surface de l'outil ne peut avoir qu'un rôle de révélateur du flux d'alimentation en inclusions provenant du copeau. On montre le rôle capital qui revient au contrôle inclusionnaire en matière de composition des inclusions principalement mais aussi en termes de morphologie et de déformabilité relative inclusion/matrice
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Sun, Wei. "Kinetics of Iron Carbonate and Iron Sulfide Scale Formation in CO2/H2S Corrosion." Ohio : Ohio University, 2006. http://www.ohiolink.edu/etd/view.cgi?ohiou1163783193.
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Genisel, Mustafa Fatih. "Synthesis Of Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn Sulfides By Solid-gas Reactions, Investigation Of Structural And Conducting Properties." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/12606746/index.pdf.
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In this study some of the first row transition metal oxides were transformed to metal sulfides by new solid gas reaction system.
Transition metal sulfides have wide application area in industry and technology. Several techniques are known for the production of metal sulfides. Such as reactions between metal or metal oxide with H2S, precipitation in several liquid medium, reaction between metal and sulfur in closed vessel, chemical vapor deposition (CVD) technique. These techniques will have some disadvantagesfor example, reactants are rarely available or expensive materials, their production systems are complicated and hard to set up these systems, products contain oxygen or hydrogen or corresponding metal sulfate as impurities. In our new sulfidizing system the reactants are metal oxides, carbon and SO2. These materials can be found easily. Especially, SO2 usage in this system is a big advantage of giving possibility of usage the hazardous waste product of SO2 in industry. The sulfidizing gas mixture was obtained by passing SO2 over activated carbon at 750 OC in a vertical tubular furnace. The obtained gas contains, mainly, CS2, CO and COS. The sulfidizing reactions took place in the horizontal tubular furnace at 450OC-1250 OC. The duration of the reaction, (three hours), and flow rate (60ml/min) of the SO2 gas were kept constant. The products were examined by X-ray powder diffraction and Raman scattering spectroscopy. All examined metal oxides were transformed to metal sulfides by sulfidizing gas mixture successfully. Ti3S5 was obtained from TiO2. Cr2S3 was obtained from Cr2O3. MnS (Alabandite) was obtained from MnO2. FeS and Fe1-xS (Pyrrhotite) were obtained from Fe2O3. Co9S8 (Cobaltpentlandite) and CoS (Jaipurite) were obtained from Co3O4. NiS was obtained from NiO. Cu7.2S, Cu1.6S (Calcocite-Q), Cu1.81S, Cu7S4 (Anilite) Cu9S5 (Digenite), Cu8S5 (Geerite) were obtained from CuO, ZnS was obtained from ZnO. The electrical conductivity character of each product obtained by sulfidizing reaction was analyzed in the temperature range of 77 K-300 K. Titanium sulfide, cobalt sulfide and nickel sulfide showed metallic conductivity, cupper sulfide and iron sulfide showed semiconductor behavior in this temperature range.
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Cooper, Matthew E. "Energy production from coal syngas containing H₂S via solid oxide fuel cells utilizing lanthanum strontium vanadate anodes." Ohio : Ohio University, 2008. http://www.ohiolink.edu/etd/view.cgi?ohiou1219867679.
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Gao, Suning [Verfasser], Rudolf [Gutachter] Holze, Rudolf [Akademischer Betreuer] Holze, and Qunting [Gutachter] Qu. "Layered transition metal sulfide- based negative electrode materials for lithium and sodium ion batteries and their mechanistic studies / Suning Gao ; Gutachter: Rudolf Holze, Qunting Qu ; Betreuer: Rudolf Holze." Chemnitz : Technische Universität Chemnitz, 2020. http://d-nb.info/1219910309/34.
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Hayes, Sarah. "Effects of Mineral Weathering and Plant Roots on Contaminant Metal Speciation and Lability in Arid Lead-Zinc Sulfide Mine Tailings at the Klondyke Superfund Site, Graham County, AZ." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/196007.
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Historic mine tailings pose a significant health risk to surrounding ecosystems and communities because of high residual concentrations of contaminant metals. The initial tailings mineral assemblage, metal sulfides, silicates, and carbonates are unstable at earth surface conditions and undergo oxidative and proton-promoted weathering. The weathering of metal sulfides generally produces acid that, if not balanced by protonconsuming dissolution of silicates and carbonates, leads to progressive acidification. The Klondyke State Superfund Site in Graham County, Arizona contains high concentrations of Pb (up to 13 g kg⁻¹) and Zn (up to 6 g kg⁻¹), and remains unvegetated 50 years after mining cessation. Field-scale investigation revealed a wide range of pH (2.5-8.0) and plant-available (DTPA-extractable) metals in the near surface of the tailings pile. Four samples were chosen for in-depth characterization ranging in pH, as denoted by subscript, from 2.6 to 5.4. The mineral transformations occurring in these four samples were investigated using a variety of techniques and the data indicated an increase in tailings weathering extent with increasing acidification (decreasing pH). Lead speciation, studied by a combination of chemical sequential extraction and X-ray absorption fine structure (XAFS) spectroscopy, was found to vary with tailings depth. The principle lead-bearing mineral was plumbojarosite (PbFe₆(SO₄)₄(OH)₁₂), with smaller amounts of anglesite (PbSO₄) and lead-sorbed iron-oxide. Anglesite, the most bioavailable mineral form of Pb in the tailings, was found to accumulate at the tailings surface, which has important implications for health risks. Total Zn content decreased by an order of magnitude (from 6 to 0.4 g kg⁻¹) and showed a change in molecular speciation with decreasing pH. Zinc-rich phyllosilicates and Zn-containing manganese oxides predominate at high pH, whereas low pH samples contained principally Zn-sorbed iron oxides. One of the overarching goals of the project is to remediate the Klondyke site using phytostabilization to keep contaminant metals from eroding offsite either by wind or water transport mechanisms. However, the impacts of plant growth on metal bonding environment are unknown. To address that gap in knowledge, we have developed a technique for the study of root-microbe-mineral-metal interactions that occur in the rhizosphere, the volume of soil surrounding, and affected by, plant roots. This technique involves the conjunctive use of fluorescence in-situ hybridization, X-ray fluorescence elemental mapping, XAFS and Raman micro-spectroscopies, and electron microscopy on single roots. Manganese and iron root plaques collocalized with elevated Pb, Zn, and Cr demonstrate that the rhizosphere can affect metal speciation. Metal speciation is an important factor in determining metal bioavailability, and thus is critical for understanding the health risk associated with mine tailings. The results of this research provides site-specific information about Pb and Zn speciation, which will be used to evaluate the effectiveness of site remediation within the context of metal toxicity.
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Hammond, Corin, and Corin Hammond. "The Biogeochemical Response of Metal(Loid)S to a Phytostabilization Remediation Approach on Acidic Iron Sulfide Tailings at the Iron King Mine and Humboldt Smelter Superfund Site in Semi-Arid Central Arizona." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/626675.
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Particulate and dissolved forms of arsenic and heavy metals are released from legacy mine tailings, particularly in (semi-) arid environments where tailings remain barren of vegetation and therefore highly susceptible to erosion. This leads to contamination of adjacent ecosystems and increased risk to public health. Establishment of a vegetative cap using amendments, such as composted organic matter to enhance plant growth, may be employed to reduce both physical erosion and leaching, but the impacts of such practices on molecular-scale mechanisms controlling metal(loid) speciation and lability remain poorly understood. Here we report on subsurface biogeochemical transformations of metal(loid)s in a phytostabilization field study at a Superfund site in Arizona, USA, where a legacy pyritic tailings (4,000 mg kg^-1 As, 2,438 mg kg^-1 Pb, 6,142 mg kg^-1 Zn, 13.25% Fe, and 11.71% S, averages for the top 0.5 m) has undergone oxidation in the top 1 m. Tailings were amended in the top 20 cm with 10%, 15%, and 20% composted organic matter by mass and seeded with native halotolerant plant species. All field treatments and the uncomposted control received irrigation of 0.36 ± 0.03 mm y^-1 in addition to 0.25 ± 0.16 mm y^-1 of precipitation, resulting in water input of 144% the annual precipitation rate. The field trial incorporated four annual samplings from 2010 – 2013. Sampling consisted of a single core of 90 cm in length and 2.54 cm in diameter collected from each field plot that was subsequently sectioned into 20 cm depth increments for analysis by synchrotron Fe and As X-ray absorption spectroscopy (XAS) coupled with quantitative chemical extraction methods. Subsurface stabilization of arsenic by Prosopis juliflora (mesquite) was investigated by bulk and micro synchrotron XAS and multiple-energy microscale fluorescence mapping combined with chemical digestion of plant samples following 1, 2, and 3 months of growth in greenhouse microcosms as well as 14 and 36 months of growth at the field site. Results indicate persistence of oxidizing conditions following compost amendment in surface tailings despite addition of organic matter, development of heterotrophic microbial communities and irrigation of a poorly draining medium. Compost amendment of 20% corresponded with evidence of higher oxidative pyrite weathering activity at 40-60 cm depth during phytostabilization compared to treatments of 0% or 10% compost for which the highest oxidative pyrite weathering activity was observed closer to the surface at 20-40 cm depth.. Despite observed downward transport of As, Fe, Zn, Mn, Pb, Ni, Cu, Cr, V, and Co during phytostabilization, ≥ 75% of total As was found to be attenuated by ferrihydrite in surface depths. Attenuation of Mn, Co, and Ni was observed below 40 depth by tailings receiving compost amendment relative to the irrigated control. Root associated As(V) was immobilized on the root epidermis bound to ferric sulfate precipitates and within root vacuoles as trivalent As(III)-thiol complexes. Rhizoplane associated ferric sulfate phases were dissimilar from the bulk tailings mineralogy shown by XAS and exhibited a high capacity to scavenge As(V) with As:Fe ratios 2x higher than the compost amended growth medium, indicating a root surface mechanism for their formation or accumulation. Results indicate that arsenate attenuation in semi-arid mine tailings during phytostabilization greatly depends on the presence of high concentrations of Fe(III) (oxyhydr)oxide minerals with a high capacity for arsenic adsorption.
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Lopes, Paula Aparecida Lima. "Aproveitamento de radiação solar na geração de hidrogênio empregando fotocatalisadores do tipo CdS, ZnS e Cd (1-x)ZnxS." Instituto de Química, 2014. http://repositorio.ufba.br/ri/handle/ri/16479.
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Energia e Ambiente ocupam posições de destaque dentre os grandes desafios da hu manidade e a produção de hidrogênio a partir da reforma foto - induzida de solução aquosa de glicerol é uma investigação de grande interesse científico e importância para a sociedade e o meio ambiente , pelo fato de gerar energia limpa a partir de fontes reno váveis e com baixo custo. Neste sentido, o presente trabalho propõe desenvolver semicondutores do tipo sulfetos metálicos e soluções sólidas do tipo Cd (1 - x) Zn x S capazes de absorver luz visível e assim conduzir a reação de decomposição da água e glicerol le vando à produção de hidrogênio assistida por um simulador de luz solar . Para tanto, foi desenvolvido um método sonoquímico de síntese de nanopartículas dos sulfetos com diferentes proporções Cd:Zn:S nas soluções de partida. As análises de difração de raios X confirmaram a obtenção das fases dos sulfetos puros e soluções sólidas. As micrografias obtidas por microscopia eletrônica de varredura revelam diferentes morfologias a depender do teor de zinco nas soluções sólidas e a formação de nanoesferas de CdS pu ro em fase hexagonal. Os materiais ainda foram caracterizados por EDX, DRS e análise textural por adsorção de N 2 . A avaliação da atividade fotocatalítica na produção de hidrogênio revelou que todas as amostras contendo Cd em sua composição foram ativas, co m exceção da amostra S 8 ( Cd:S 1:8). O fotocatalisador que apresentou melhor atividade foi a solução sólida obtida com a proporção 1:8:4 (Cd:Zn:S), com uma taxa de produção de hidrogênio de 239 mol g - 1 h - 1 . Os resultados demonstraram que a introdução de zinco na matriz wurtzita de CdS aumenta a atividade fotocatalítica e a estab ilidade do fotocatalisador em me io aquoso.
Energy and Environment are ones of the great challenges of humanity and the production of hydrogen from photo - induced reforming of glycerol aqueous solution is an investigation of great scientific interest and importan t fo r the society and the environment . This process can generate clean e nergy from renewable sources with low cost. In this sense, the present work proposes to develop semiconductor s, metal sulfide type and solid solutions type, Cd (1 - x) Zn x S , able to absorb vis ible light and decompos e water and glycerol leading to hydrogen production assisted by a simulator sunlight. Thus , it was developed a sonochemical method to synthesi ze semiconductor nanopar ticles with different Cd:Zn:S ratios in starting solutions. X - ray d iffraction analysi s confirmed the formation of pure sulfides and solid solutions phase s . The micrographs obtained by scanning electron microscopy reveal different morphologies depending on the zinc content in the solid solutions and the formation of CdS na no - spheres in hexagonal pure phase. The material s w ere also ch aracterized by EDX, DRS and textural analysi s by N 2 adsorption . The assessment of photocatalytic activity in hydrogen production showed that all samples containing Cd were active with respect to hydrogen production , exception S 8 sample ( Cd:S 1:8). The photocatalyst that showed the best activity was the solid solution obtained with the ratio 1:8:4 (Cd:Zn:S), with a hydrogen production rate of 239 μmol g - 1 h - 1 . The results demonstrated that the int roduction of zinc in CdS wurtzite matrix increases the photocatalyt ic activity and stability of the photocatalyst in aqueous medium
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Yuan, Yanan. "Oxidative of organic compounds by oxysulfur radicals in the presence of transition metal ions and sulfite." Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAC052.
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Ces dernières années, de plus en plus de composés organiques réfractaires et toxiques ont été détectés dans les eaux usées. Un bon nombre de ces polluants organiques sont difficilement dégradés par des traitements classiques. Les procédés d’oxydation avancée à base de radicaux sulfates (SR-AOP) sont apparus comme une méthode innovante dans le domaine de la décontamination oxydative des eaux polluées. Des études antérieures ont porté sur ces SR-AOP utilisant du peroxodisulfate (PS) ou du peroxomonosulfate (PMS) comme oxydants, en particulier des couples «métaux de transition et oxydants» (systèmes Fe (II)/PS, systèmes Ni(II)/PMS et Co (II))/PMS), où il a été confirmé que SO4•-·présentent des avantages (sélectivité) par rapport au radical hydroxyle (HO•) pour la décontamination des eaux usées contenant des polluants organiques.Dans cette thèse, nous avons généré des radicaux tels que le radical sulfite SO3•-, le radical sulfate SO4•-, le radical peroxomonosulfate SO5•- à partir d’ions métalliques (Cr(VI), le Co(II), le Fe(III)) capables d’activer le sulfite pour la dégradation des composés organiques. L'efficacité d'élimination et le mécanisme d'oxydation ont été étudiés et le rôle des espèces soufrées a été élucidéIn recent years, more and more refractory and toxic organic compounds are detected in wastewater. Many of these organic pollutants can hardly be degraded by conventional water treatments. Sulfate radical based advanced oxidation process (SR-AOPs), have emerged as a promising method in the field of oxidative decontamination of polluted water. Past studies focused on this SR-AOPs with peroxydisulfate (PS) or peroxymonosulfate (PMS) as oxidants, especially the ‘transition metal + oxidants’ (i.e. Fe(II)/PS system, Ni(II)/PMS system and Co(II)/PMS system), which has been confirmed that SO4·− has advantages over HO in the decontamination of wastewater containing organic pollutants. In this PhD thesis, oxysulfur radicals including sulfite radical SO3·−, sulfate radical SO4·−, peroxymonosulfate radical SO5·− produced by transition metal ions such as Cr(VI), Co(II), Fe(III) activated sulfite were used to degrade organic compounds. The removal efficiency, the oxidation mechanism were examined, and and the role of sulfur species were elucidated
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Ferraina, Clément. "Partage des métaux entre liquide sulfuré et liquide silicaté : Expérimentation, modélisation et applications aux gisements de sulfures magmatiques." Thesis, Orléans, 2018. http://www.theses.fr/2018ORLE2004/document.
Full textAbstract:
Comprendre l’enrichissement des liquides sulfurés en éléments chalcophiles et sidérophiles pouvantmener à la formation de gisements de sulfures magmatiques.Le premier objectif de cette thèse a été de quantifier les variations des coefficients de partage (Dsul/sil)de Co, Ni, Cu, Pd, Ag, Pt et Au dans des conditions crustales typiques des intrusions de la région deNoril’sk-Talnakh (Russie), par le biais d’une étude expérimentale en autoclave à chauffage interne,effectuée à 1200 °C, 70 MPa, sous différentes fugacités d’oxygène.Les résultats montrent que les Dsul/sil de Pd, Ag, Pt et Au augmentent avec la teneur de ces élémentsdans le liquide sulfuré, indiquant qu’ils ne suivent pas la loi de Henry, au contraire de ceux de Co, Ni, etCu. Ces Dsul/sil permettent de reproduire les teneurs en métaux des sulfures naturels de la région deNoril’sk, à partir d’un magma parent plus enrichi en Pd et Pt que les laves de la région, et en invoquantl’interaction entre des masses de liquide silicaté et de liquide sulfuré pour pouvoir enrichir ce dernier(facteur R entre 300 et 1000 pour les sulfures massifs et entre 300 et 6000 pour les disséminés).Le second objectif de cette thèse a été de modéliser, par une approche thermodynamique, les variationsdes Dsul/sil en fonction des conditions magmatiques. Ce modèle décrit les variations des Dsul/sil avec latempérature, la pression, la fugacité d’oxygène et la chimie des liquides, et suggère que les magmasmafiques à l’équilibre avec les liquides sulfurés les plus enrichis sont ceux qui ont les plus faiblestempératures et pressions, et les fugacités d’oxygène les plus élevéesA comprehensive knowledge of metal partitioning between sulfide liquid and silicate melt is essential tounderstand sulfide liquid enrichment in chalcophile and siderophile elements that can lead to theformation of magmatic sulfide ore deposits.The first aim of this thesis was to quantify the partition coefficients (Dsul/sil) for Co, Ni, Cu, Pd, Ag, Pt andAu at crustal conditions relevant to the Noril’sk-Talnakh region (Russia), through an experimental studyconducted in internal heated pressure vessels at 1200 °C, 70 MPa, and under variable oxygenfugacities.Our results show that Dsul/sil for Pd, Ag, Pt and Au increase with the content of the element in the sulfideliquid, showing that they do not follow Henry’s law, in contrast to those for Co, Ni, and Cu. These Dsul/silcan reproduce the metal contents of natural sulfides of the Noril’sk region, starting from a parent magmaPd- and Pt-richer than the lavas of the region, and invoking an interaction between the masses of silicateliquid and sulfide liquid in order to enrich the latter.The second objective of this thesis was to model Dsul/sil variations as a function of magmatic conditions,using a thermodynamic approach. This modeling allows investigating the variations of Dsul/sil withtemperature, pressure, oxygen fugacity and the compositions of both liquids and suggests that the maficmagmas with the lowest temperatures and pressures and the highest oxygen fugacities are those inequilibrium with the most enriched sulfide liquid