Showing papers on "Sulfide published in 2003"
TL;DR: In this paper, the authors show that the dominance of At. ferrooxidans or Leptospirillum in mesophilic leaching habitats is highly likely to result from differences in their biochemical iron(II) oxidation pathways, especially the involvement of rusticyanin.
Abstract: Bioleaching of metal sulfides is caused by astonishingly diverse groups of bacteria. Today, at least 11 putative prokaryotic divisions can be related to this phenomenon. In contrast, the dissolution (bio)chemistry of metal sulfides follows only two pathways, which are determined by the acid-solubility of the sulfides: the thiosulfate and the polysulfide pathway. The bacterial cell can effect this sulfide dissolution by “contact” and “non-contact” mechanisms. The non-contact mechanism assumes that the bacteria oxidize only dissolved iron(II) ions to iron(III) ions. The latter can then attack metal sulfides and be reduced to iron(II) ions. The contact mechanism requires attachment of bacteria to the sulfide surface. The primary mechanism for attachment to pyrite is electrostatic in nature. In the case of Acidithiobacillus ferrooxidans, bacterial exopolymers contain iron(III) ions, each complexed by two uronic acid residues. The resulting positive charge allows attachment to the negatively charged pyrite. Thus, the first function of complexed iron(III) ions in the contact mechanism is mediation of cell attachment, while their second function is oxidative dissolution of the metal sulfide, similar to the role of free iron(III) ions in the non-contact mechanism. In both cases, the electrons extracted from the metal sulfide reduce molecular oxygen via a complex redox chain located below the outer membrane, the periplasmic space, and the cytoplasmic membrane of leaching bacteria. The dominance of either At. ferrooxidans or Leptospirillum ferrooxidans in mesophilic leaching habitats is highly likely to result from differences in their biochemical iron(II) oxidation pathways, especially the involvement of rusticyanin.
1,033 citations
TL;DR: Evidence for physiological synergy in iron, sulfur, and carbon flow in these communities is reviewed, and microbial and geochemical simplicity of these systems makes them ideal targets for quantitative, genomic-based analyses of microbial ecology and evolution and community function.
1,033 citations
TL;DR: Ni2P/SiO2 catalysts with varying Ni/P ratios have been shown to have better performance in hydroprocessing than a commercial Ni-Mo-S/Al2O3 (HDS 98% vs 78% and HDN 80% vs 43%), based on equal sites loaded in the reactor.
715 citations
TL;DR: The synthesis of semiconductor nanocrystals of PbS, ZnS, CdS, and MnS through a facile and inexpensive synthetic process and all of the synthesized nanocry crystals were highly crystalline.
Abstract: We report on the synthesis of semiconductor nanocrystals of PbS, ZnS, CdS, and MnS through a facile and inexpensive synthetic process. Metal−oleylamine complexes, which were obtained from the reaction of metal chloride and oleylamine, were mixed with sulfur. The reaction mixture was heated under appropriate experimental conditions to produce metal sulfide nanocrystals. Uniform cube-shaped PbS nanocrystals with particle sizes of 6, 8, 9, and 13 nm were synthesized. The particle size was controlled by changing the relative amount of PbCl2 and sulfur. Uniform 11 nm sized spherical ZnS nanocrystals were synthesized from the reaction of zinc chloride and sulfur, followed by one cycle of size-selective precipitation. CdS nanocrystals that consist of rods, bipods, and tripods were synthesized from a reaction mixture containing a 1:6 molar ratio of cadmium to sulfur. Spherical CdS nanocrystals (5.1 nm sized) were obtained from a reaction mixture with a cadmium to sulfur molar ratio of 2:1. MnS nanocrystals with v...
624 citations
TL;DR: In this paper, the authors investigated reactions of As(III) with iron sulfide and pyrite (FeS2) as a function of total arsenic concentration, suspension density, sulfide concentration, pH, and ionic strength.
389 citations
TL;DR: This article measured multiple sulfur isotope ratios for sulfide sulfur in shale and carbonate lithofacies from the Hamersley Basin, Western Australia, and found a similar positive correlation between v 33 S and N 34 S. The results were explained by a combination of massindependent fractionation (MIF) in the atmosphere and biological mass-dependent fractionation in the ocean.
351 citations
TL;DR: A new chromo-chemodosimeter for the anion sulfide in aqueous environments has been developed, suggesting potential applications in a variety of different environments where easy and rapid determination of sulfide might be required.
Abstract: A new chromo-chemodosimeter for the anion sulfide in aqueous environments has been developed. The recognition concept is based on a pyrylium-thiopyrylium transformation that is conveniently drawn toward "color chemistry" concepts by means of the anchoring of an aniline group. This causes the color of the aniline-pyrylium backbone in L1 to change selectively from magenta to blue when transformed to the corresponding aniline-thiopyrylium in the presence of the sulfide anion. The method is simple and easy, suggesting potential applications in a variety of different environments where easy and rapid determination of sulfide might be required.
339 citations
TL;DR: A strongly growing microbially-based metal extraction industry, which uses either rapid stirred-tank or slower irrigation technology to recover metals from an increasing range of minerals using a diversity of microbes that grow at a variety of temperatures is reviewed.
335 citations
TL;DR: In this paper, the formation of indium sulfide buffer layers for high-efficiency copper indium gallium diselenide (CIGS) thin-film solar cells with atomic layer chemical vapour deposition (ALCVD) was studied.
Abstract: This paper presents optimization studies on the formation of indium sulfide buffer layers for high-efficiency copper indium gallium diselenide (CIGS) thin-film solar cells with atomic layer chemical vapour deposition (ALCVD) from separate pulses of indium acetylacetonate and hydrogen sulfide. A parametric study of the effect of deposition temperature between 160° and 260°C and thickness (15–30 nm) shows an optimal value at about 220°C for a layer thickness of 30 nm, leading to an efficiency of 16·4%. Analysis of the device shows that indium sulfide layers are characterised by an improvement of the blue response of the cells compared with a standard CdS-processed cell, due to a high apparent band gap (2·7–2·8 eV), higher open-circuit voltages (up to 665 mV) and fill factor (78%). This denotes high interface quality. Atomic diffusion processes of sodium and copper in the buffer layer are demonstrated. Copyright © 2003 John Wiley & Sons, Ltd.
310 citations
TL;DR: The design of future processes is based on the identification of the refractory sulfur compounds and the knowledge of their individual reactivity and in the presence of inhibitors, as illustrated in this paper.
289 citations
TL;DR: A biochemical model for elemental sulfur and sulfide oxidation in Acidithiobacillus and Acidiphilium spp.
Abstract: To identify the actual substrate of the glutathione-dependent sulfur dioxygenase (EC 1.13.11.18) elemental sulfur oxidation of the meso-acidophilic Acidithiobacillus thiooxidans strains DSM 504 and K6, Acidithiobacillus ferrooxidans strain R1 and Acidiphilium acidophilum DSM 700 was analysed. Extraordinarily high specific sulfur dioxygenase activities up to 460 nmol x min(-1) (mg protein)(-1) were found in crude extracts. All cell-free systems oxidized elemental sulfur only via glutathione persulfide (GSSH), a non-enzymic reaction product from glutathione (GSH) and elemental sulfur. Thus, GSH plays a catalytic role in elemental sulfur activation, but is not consumed during enzymic sulfane sulfur oxidation. Sulfite is the first product of sulfur dioxygenase activity; it further reacted non-enzymically to sulfate, thiosulfate or glutathione S-sulfonate (GSSO(-3)). Free sulfide was not oxidized by the sulfur dioxygenase. Persulfide as sulfur donor could not be replaced by other sulfane-sulfur-containing compounds (thiosulfate, polythionates, bisorganyl-polysulfanes or monoarylthiosulfonates). The oxidation of H(2)S by the dioxygenase required GSSG, i.e. the disulfide of GSH, which reacted non-enzymically with sulfide to give GSSH prior to enzymic oxidation. On the basis of these results and previous findings a biochemical model for elemental sulfur and sulfide oxidation in Acidithiobacillus and Acidiphilium spp. is proposed.
TL;DR: In this article, a synthesis of metal sulfide nanoparticles at relatively low temperature with use of a single precursor under ambient conditions is described, where metal alkyl xanthates (as well as thiocarbamates and thiocalarbonates) are used as the precursor.
Abstract: A synthesis of various metal sulfide nanoparticles at relatively low temperature with use of a single precursor under ambient conditions is described. Metal alkyl xanthates (as well as thiocarbamates and thiocarbonates) are used as the precursor. Lewis base alkylamine solvents promote the reaction at low temperatures (from below room temperature up to ∼150 °C). By this method we form crystalline particles which are size- and shape-tunable and are usually monodiserse. This tunability is achieved by controlling parameters such as the reaction temperature, the reaction time, the concentration of the precursor, and the alkyl chain length. Core/shell structures are synthesized with the same method, using the same precursors, applying either a single-step or a dual-step process. CdS spherical particles, for instance, exhibit a narrow (∼30 nm fwhm) tunable excitonic fluorescence, and a broad, long wavelength defect emission, which intensity can be adjusted in a controlled manner, and even totally eliminated. Qua...
TL;DR: In this article, the effect of refertilization processes on the PGE systematics of abyssal peridotites was investigated using 19 samples from the Kane Fracture Zone.
TL;DR: The opaque mineralogy and the contents and isotope compositions of sulfur in serpentinized peridotites from the MARK (Mid Atlantic Ridge, Kane Fracture Zone) area were examined to understand the conditions of serpentinization and evaluate this process as a sink for seawater sulfur.
TL;DR: In this paper, water column dissolved oxygen, sulfide, nitrate and nitrite, pore water profiles for dissolved sulfide and sulfate, 35 S-sulfate reduction rates, as well as bacterial counts of large sulfur bacteria from 20 stations across the continental shelf and slope.
TL;DR: In this article, the reaction between synthetic ferrihydrite and dissolved sulfide was studied in artificial seawater and 0.42 M NaCl at 25 °C over the pH range 4.0-8.2.
TL;DR: Preliminary data indicate that strains of Acidithiobacillus ferrooxidans, with a high amount of iron( III) ions in their extracellular polymeric substances, possess a higher oxidation activity than those with less iron(III) ions.
TL;DR: In this paper, MoS 2 nanowires with diameters of 4nm and lengths of 50nm were synthesized by a hydrothermal method using 0.36 g MoO 3 and 1.8 g Na 2 S as precursors in 0.4 mol/l HCl solution at 260°C.
TL;DR: Horizontal and vertical patterns of sulfide availability have a strong influence on the fine-scale distribution, structure and composition of macrofaunal assem- blages inhabiting methane seeps and must be accounted for when characterizing the microbiology and ecology of seep habitats.
Abstract: Relationships among fluid flow, sulfide concentration, sulfur bacteria and macrofaunal assemblages were examined at methane seeps on the northern California margin, near the mouth of the Eel River (512 to 525 m). Over a 6 mo period, sediments covered with microbial mats exhibited significant but variable outflow of altered fluids, with no flow reversals. This fluid flow was associated with high porewater sulfide concentrations (up to 20 mM) and almost no oxygen penetration of sedi- ments ( 300 µm), but biomass and diversity (no. species per core, E(S100), H ') were lower and composition varied in the sulfidic microbial mat sediments relative to clam-bed and non-seep sediments. The community in microbial mat-covered sediments consisted largely (82%) of 6 species in the polychaete family Dorvilleidae, whereas the clam-bed and non-seep microhabitats supported a mixture of annelids, peracarid crustaceans, nemerteans, and mollusks. Vertical microprofiling of sulfide in animal cores indicated that most taxa avoid H2S concentrations >1 mM. However, sulfide-oxidizing filamentous bacteria, dorvilleid polychaetes and bivalves (mainly V. pacifica) exhibited highest densities at sul- fide concentrations of 1 to 5 mM sulfide. Horizontal and vertical patterns of sulfide availability have a strong influence on the fine-scale distribution, structure and composition of macrofaunal assem- blages inhabiting methane seeps and must be accounted for when characterizing the microbiology and ecology of seep habitats.
TL;DR: The results of bench-scalestudies conducted to develop a resource recovery basedmediation process for the clean up of the Berkeley Pit showed water quality of this agriculturally usable watermet the EPA's gold standard criterion.
Abstract: Acid mine drainage (AMD), an acidic metal-bearing wastewater, poses a severe pollution problem attributed to post mining activities. The metals usually encountered in AMD and considered of concern for risk assessment are arsenic, cadmium, iron, lead, manganese, zinc, copper and sulfate. The pollution generated by abandoned mining activities in the area of Butte, Montana has resulted in the designation of the Silver Bow Creek-Butte Area as the largest Superfund (National Priorities List) site in the U.S. This paper reports the results of bench-scale studies conducted to develop a resource recovery based remediation process for the clean up of the Berkeley Pit. The process utilizes selective, sequential precipitation (SSP) of metals as hydroxides and sulfides, such as copper, zinc, aluminum, iron and manganese, from the Berkeley Pit AMD for their removal from the water in a form suitable for additional processing into marketable precipitates and pigments. The metal biorecovery and recycle process is based on complete separation of the biological sulfate reduction step and the metal precipitation step. Hydrogen sulfide produced in the SRB bioreactor systems is used in the precipitation step to form insoluble metal sulfides. The average metal recoveries using the SSP process were as follows: aluminum (as hydroxide) 99.8%, cadmium (as sulfide) 99.7%, cobalt (as sulfide) 99.1% copper (as sulfide) 99.8%, ferrous iron (sulfide) 97.1%, manganese (as sulfide) 87.4%, nickel (as sulfide) 47.8%, and zinc (as sulfide) 100%. The average precipitate purity for metals, copper sulfide, ferric hydroxide, zinc sulfide, aluminum hydroxide and manganese sulfide were: 92.4, 81.5, 97.8, 95.6, 92.1 and 75.0%, respectively. The final produced water contained only calcium and magnesium and both sulfate and sulfide concentrations were below usable water limits. Water quality of this agriculturally usable water met the EPA's gold standard criterion.
TL;DR: In this article, the authors investigated the timing and possible pathways of organic matter (OM) sulfurization in marine sediments from the Cariaco Basin, Venezuela and found that organic sulfur is derived primarily from pore-water sulfide, with minor contributions from primary bio-sulfur (e.g., in proteins derived from algae and bacteria).
TL;DR: A biofilm-forming strain of sulfate-reducing bacteria (SRB), isolated from a naturally occurring mixed biofilm and identified by 16S rDNA analysis as a strain of Desulfomicrobium norvegicum, rapidly removed 200 μM selenite from solution during growth on lactate and sulfate.
Abstract: A biofilm-forming strain of sulfate-reducing bacteria (SRB), isolated from a naturally occurring mixed biofilm and identified by 16S rDNA analysis as a strain of Desulfomicrobium norvegicum, rapidly removed 200 micro M selenite from solution during growth on lactate and sulfate. Elemental selenium and elemental sulfur were precipitated outside SRB cells. Precipitation occurred by an abiotic reaction with bacterially generated sulfide. This appears to be a generalized ability among SRB, arising from dissimilatory sulfide biogenesis, and can take place under low redox conditions and in the dark. The reaction represents a new means for the deposition of elemental sulfur by SRB under such conditions. A combination of transmission electron microscopy, environmental scanning electron microscopy, and cryostage field emission scanning electron microscopy were used to reveal the hydrated nature of SRB biofilms and to investigate the location of deposited sulfur-selenium in relation to biofilm elements. When pregrown SRB biofilms were exposed to a selenite-containing medium, nanometer-sized selenium-sulfur granules were precipitated within the biofilm matrix. Selenite was therefore shown to pass through the biofilm matrix before reacting with bacterially generated sulfide. This constitutes an efficient method for the removal of toxic concentrations of selenite from solution. Implications for environmental cycling and the fate of sulfur and selenium are discussed, and a general model for the potential action of SRB in selenium transformations is presented.
TL;DR: The precise control over the particle size enables tuning the absorption and emission spectra of the particles, and the relative intensity of the narrow and broad emission associated with deep surface traps is controlled.
Abstract: We present a simple and versatile method for the synthesis of high-quality size-controlled metal sulfide nanoparticles. A single compound (metal xanthate) is the precursor. A Lewis-base solvent is used to achieve a low reaction temperature of 50-150 degrees C, usually in air. Demonstrated with CdS, the precise control over the particle size (by regulating the temperature or the concentration) enables tuning the absorption and emission spectra of the particles. We also can control the relative intensity of the narrow (30-35 nm wide) excitonic emission (tunable in the range 430-480 nm with approximately 2% fluorescence quantum efficiency) and the broad emission associated with deep surface traps (in the range 550-700 nm). Using the same precursor CdS/ZnS core/shell particles are produced with a high PL yield ( approximately 14%).
25 Sep 2003-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the influence of microstructure on HIC and SSCC behavior of two low C-Mn-Nb-Mo API linepipe steels has been investigated.
Abstract: The chemical composition and microstructure are known to have a significant effect on the resistance to hydrogen induced cracking (HIC) and sulfide stress corrosion cracking (SSCC) of structural steels in wet H2S environments. In this paper, the influence of microstructure on HIC and SSCC behavior of two low C–Mn–Nb–Mo API linepipe steels has been investigated. Subjecting the steel to different thermomechanical processes modified the microstructure. The results showed that refined and homogeneous quenched and tempered bainite/martensite microstructures had the best performance with respect to both HIC and SSCC susceptibility.
TL;DR: In this article, X-ray absorption fine structure (XAFS) was used to analyze the solid electrolyte interface (SEI) layer on the graphite anode and the LiCoO2 cathode in a lithium-ion battery.
TL;DR: In this paper, the surface oxidation phase on pyrite, FeS2, reacted in aqueous electrolytes at pH = 2 to 10 and with air under ambient atmospheric conditions was studied using synchrotron-based oxygen K edge, sulfur LIII edge, and iron LII,III edge X-ray absorption spectroscopy.
TL;DR: In this article, the authors demonstrate the efficiency of reactions that involve the exchange of Fe for Cu, Ni, or PGE in producing increases in the metal tenor of the accumulated sulfide.
Abstract: Sulfur isotope measurements provide a useful means of evaluating the source of sulfur in magmatic Cu-Ni-PGE deposits. Although low sulfur, PGE-rich deposits (e.g., J-M reef of the Stillwater Complex, Merensky reef of the Bushveld Complex) show little or no isotopic evidence for the involvement of crustally derived sulfur, several high sulfur deposits (e.g., Noril’sk, Duluth Complex) show strong evidence for contamination of mafic magmas by sulfur of crustal origin. Processes such as magma degassing or redox changes accompanying crystallization are ineffective in significantly modifying sulfur isotope signatures of sulfides that crystallize from immiscible liquids that exsolve from the mafic magmas. For this reason δ 34S values are primarily dependent on sulfur source characteristics, and variations can often be treated using a two-component mixing approach. However, deposits such as those at Noril’sk and Voisey’s Bay that appear to have formed in magma conduit systems present another possibility for modification of sulfur isotope signatures. These deposits are thought to have been upgraded in metal tenor by reaction with uncontaminated mantle-derived melts that traversed the accumulated sulfide on their way to the surface. Our calculations illustrate the efficiency of reactions that involve the exchange of Fe for Cu, Ni, or PGE in producing increases in the metal tenor of the accumulated sulfide. Sulfur isotope exchange between the crustally contaminated sulfide ore accumulation and sulfur of mantle origin may accompany chalcophile element exchange, and is capable of masking or limiting the degree of isotopic evidence for the initial stage of ore genesis that involved crustal sulfur. Sulfur isotope exchange is distinct from the addition of sulfur ( in the form of immiscible sulfide droplets from a sulfide-saturated magma) to the accumulated sulfide, although both additive mixing and exchange can lead to similar isotopic effects. Stable isotopic exchange provides a mechanism in addition to additive mixing that may lead to decoupling of different isotopic systems.
TL;DR: In this paper, the authors present results of incubation studies conducted at low temperatures (∼4°C) in the vicinity of a seafloor hydrothermal vent system.
TL;DR: In this paper, the authors measured and analyzed electrochemical impedance spectroscopy (EIS) data from the 316 stainless steel/simulated cooling water system, among the four selected passivation models, the equivalent circuit of Model D is most consistent with the conditions of this system.