Showing papers on "Sulfide published in 1996"

Sulfate‐reducing bacteria

Abstract: The corrosion of sewers and the control of odor are the major operational and maintenance problems in wastewater collection systems. The generation of hydrogen sulfide and subsequent sulfuric acid results from microbially mediated reactions, by sulfate‐reducing bacteria (SBR) and sulfide‐oxidizing bacteria. This review covers pertinent information about sulfate reduction‐induced problems in general and SBR in particular. Metabolism with respect to carbon, energy, and sulfur sources, ecology, growth factors (dissolved oxygen, temperature, pH, and sulfide), and the competitive effects of methane‐producing bacteria on SBR are discussed. Because metals react with sulfide to form metal sulfide precipitates with extremely low solubilities, metal interactions in sulfate reduction environments are discussed.

Technical basis and proposal for deriving sediment quality criteria for metals

Abstract: In developing sediment quality criteria (SQC) for metals, it is essential that bioavailability be a prime consideration. Different studies have shown that while dry weight metal concentrations in sediments are not predictive of bioavailability, metal concentrations in interstitial (pore) water are correlated with observed biological effects. A key partitioning phase controlling cationic metal activity and toxicity in the sediment-interstitial water system is acid-volatile sulfide (AVS). Acid-volatile sulfide binds, on a mole-to-mole basis, a number of cationic metals of environmental concern (cadmium, copper, nickel, lead, zinc) forming insoluble sulfide complexes with minimal biological availability. Short-term (10-d) laboratory studies with a variety of marine and freshwater benthic organisms have demonstrated that when AVS concentrations in spiked or field-collected sediments exceed those of metals simultaneously extracted with the AVS, interstitial water metal concentrations remain below those predicted to cause effects, and toxicity does not occur. Similar observations have been made in life-cycle laboratory toxicity tests with amphipods and chironomids in marine and freshwater sediments spiked with cadmium and zinc, respectively. In addition, field colonization experiments, varying in length from several months to more than 1 year, with cadmium- or zinc-spiked freshwater and marine sediments, have demonstrated a lack of biological effects when theremore » is sufficient AVS to limit interstitial water metal concentrations. These studies on metal bioavailability and toxicity in sediments serve as the basis for proposed SQC for the metals cadmium, copper, nickel, lead, and zinc.« less

Mechanism for the formation of elemental sulfur from aqueous sulfide in chemical and microbiological desulfurization processes

Abstract: A detailed reaction mechanism is proposed for the formation of crystalline elemental sulfur from aqueous sulfide by oxidation with transition-metal ions like VV, FeIII, CuII, etc. The first step is the formation of HS• radicals by one-electron oxidation of HS- ions. These radicals exist at pH values near 7 mainly as S•-. Their spontaneous decay results in the formation of the disulfide ion S22-. The further oxidation of disulfide either by S•- radicals or by the transition-metal ions yields higher polysulfide ions from which the homocyclic sulfur molecules S6, S7, and S8 are formed. In water these hydrophobic molecules form clusters which grow to droplets of liquid sulfur (sulfur sol). Depending on the composition of the aqueous phase, crystallization of the liquid sulfur as either α- or β-S8 is rapid or delayed. Surfactants delay this solidification, while certain cations promote it. All these reactions are proposed to take place in desulfurization plants working by the Stretford, Sulfolin, Lo-Cat, SulFe...

Characterization of 16S rRNA Genes from Oil Field Microbial Communities Indicates the Presence of a Variety of Sulfate- Reducing, Fermentative, and Sulfide-Oxidizing Bacteria

Abstract: Oil field bacteria were characterized by cloning and sequencing of PCR-amplified 16S rRNA genes. A variety of gram-negative, sulfate-reducing bacteria was detected (16 members of the family Desulfovibrionaceae and 8 members of the family Desulfobacteriaceae). In contrast, a much more limited number of anaerobic, fermentative, or acetogenic bacteria was found (one Clostridium sp., one Eubacterium sp., and one Synergistes sp.). Potential sulfide oxidizers and/or microaerophiles (Thiomicrospira, Arcobacter, Campylobacter, and Oceanospirillum spp.) were also detected. The first two were prominently amplified from uncultured production water DNA and represented 28 and 47% of all clones, respectively. Growth on media containing sulfide as the electron donor and nitrate as the electron acceptor and designed for the isolation of Thiomicrospira spp. gave only significant enrichment of the Campylobacter sp., which was shown to be present in different western Canadian oil fields. This newly discovered sulfide oxidizer may provide a vital link in the oil field sulfur cycle by reoxidizing sulfide formed by microbial sulfate or sulfur reduction.

Continuous in-situ combination process for upgrading heavy oil

Abstract: The invention relates to an integrated, continuous process for the removal of organically bound sulfur (e.g., mercaptans, sulfides and thiophenes) comprising the steps of contacting a heavy oil, sodium hydroxide, hydrogen and water at a temperature of from about 380°C to 450°C to partially desulfurize the heavy oil and to form sodium sulfide, contacting said sodium sulfide with a transition metal in water to form a transition metal sulfide, sodium hydroxide and hydrogen. The sodium hydroxide is recirculated and the transition metal sulfide is removed. The partially desulfurized, dewatered heavy oil is treated with sodium metal under desulfurizing conditions, typically at a temperature of from about 340°C to about 450°C, under a hydrogen pressure of at least about 50 psi to essentially desulfurize the oil, and form sodium sulfide. Optionally, the sodium salt generated can be regenerated to sodium metal using regeneration technology. The process advantageously produces essentially sulfur-free product oils having reduced nitrogen, oxygen and metals contents and reduced viscosity, density, molecular weight and heavy ends.

Chemical vapor deposition of metal sulfide films from metal thiocarboxylate complexes with monodentate or multidentate ligands

Abstract: In a method of depositing a metal sulfide film on a substrate (7), a solution containing at least one metal compound precursor comprising at least one thiocarboxylate ligand SECR, wherein E is selected from the group consisting of O and S and wherein R is selected from the group consisting of alkyl, aryl, substituted alkyl, substituted aryl, halogenated alkyl, and halogenated aryl is prepared. The substrate in a substrate chamber (4) is heated to a reaction temperature by a heating means (5). The solution is evaporated to form vapors of the metal compound precursor by the use of an aerosol generator (1). The vapors and the substrate heated to the reaction temperature are contacted. The reaction temperature is sufficient to decompose the metal compound precursor to form a metal sulfide film of at least one metal on the substrate.

Antagonistic effects of sulfide and butyrate on proliferation of colonic mucosa: a potential role for these agents in the pathogenesis of ulcerative colitis.

Abstract: It has been shown that feces of patients with ulcerative colitis uniformly contain sulfate reducing bacteria. Sulfide produced by these bacteria interferes with butyrate-dependent energy metabolism of cultured colonocytes and may be involved in the pathogenesis of ulcerative colitis. Mucosal biopsies from the sigmoid rectum of 10 patients (no caner, polyps, inflammatory bowel disease) were incubated with either NaCl, sodium hydrogen sulfide (1 mmol/L), a combination of both sodium hydrogen sulfide and butyrate (10 mmol/L), or butyrate. Mucosal proliferation was assessed by bromodeoxyuridine labeling of cells in S-phase. Compared to NaCl, sulfide increased the labeling of the entire crypt significantly, by 19% (p < 0.05). This effect was due to an expansion of the proliferative zone to the upper crypt (compartments 3-5), where the increase in proliferation was 54%. Sulfide-induced hyperproliferation was reversed when samples were coincubated with sulfide and butyrate. The study shows that sodium hydrogen sulfide induces mucosal hyperproliferation. Our data support a possible role of sulfide in the pathogenesis of UC and confirm the role of butyrate in the regulation of colonic proliferation and in the treatment of UC.

Synthesis of Poly(phenylene sulfide sulfonic acid) via Poly(sulfonium cation) as a Thermostable Proton-Conducting Polymer

Abstract: Highly sulfonated poly(phenylene sulfide) prepared from the polysulfonium cation exhibits excellent thermal stability (T d = 265°C) and high conductivity (> 10 -2 S/cm). These properties arise from the two sulfonic acid groups substituted on one phenyl ring

Disproportionation of inorganic sulfur compounds by the sulfate-reducing bacterium Desulfocapsa thiozymogenes gen. nov., sp. nov.

Abstract: A new strictly anaerobic, gram-negative bacterium was isolated from the sediment of a freshwater lake after enrichment with thiosulfate as the energy source The strain, named Bra2 (DSM 7269), is able to grow by disproportionation of thiosulfate or sulfite to sulfate plus sulfide Elemental sulfur is also disproportionated to sulfate and sulfide, but this only supports growth if free sulfide is chemically removed from the culture, eg, by precipitation with amorphous ferric hydroxide Growth is also possible by coupling the reduction of sulfate to sulfide with the oxidation of ethanol, propanol, or butanol to the corresponding fatty acid The cells are rod-shaped, motile, and have genomic DNA with a mol% G+C content of 507 Cytochromes are present, but desulfoviridin is not The new strain was shown to be related to, but distinct from members of the genus Desulfobulbus on the basis of physiological characteristics and by comparative sequence analysis of its 16S rDNA Strain Bra2 is described as the type strain of a new taxon, Desulfocapsa thiozymogenes gen nov, sp nov

Fractional crystallization of sulfide ore liquids at high temperature

Abstract: Tie line compositions of (Fe, Ni, Cu) (sub 1-x) S (monosulfide solid solution, mss) and Fe-Ni-Cu-S liquid, in the presence of sulfur vapor, have been quenched from temperatures between 1,050 degrees and 1,180 degrees C. More than 80 bulk compositions on both sulfur-rich and sulfur-poor sides of the mss field were investigated by sealed silica tube techniques.Qualitative observations of wetting behavior suggest increasing mobility in a silicate host rock, as sulfide liquids become more Cu rich. Partition coefficients for copper > or = 0.25, D (super mss/hq) Cu , are obtained from Ni-bearing experiments with approximately 2 wt percent Cu and no quench phases. The equation D (super mss/hq) Cu = 0.0003 X T( degrees C) + 0.0310 X (wt % S) + 0.0069 X (wt % Cu)--1.3450 describes partitioning observed in Ni-free experiments above 1,000 degrees C. Above 1,000 degrees C, the Ni distribution coefficient D (super mss/hq) Cu decreases with increasing temperature and/or sulfur content of the liquid.These results yield improved models describing the fractional crystallization of natural sulfide liquids. Major element (Fe, Ni, Cu, S) compositions of ores from the Sudbury district are shown to be entirely consistent with fractional crystallization at temperatures above 1,000 degrees C, with the possible exception of rare samples enriched in both Ni and Cu. Sulfide liquids fractionating Ni-Fe-rich hanging-wall ores at Sudbury, Ontario, must have been less Cu rich than previously thought. At temperatures above 950 degrees C, reduced sulfur activity in residual liquids can result in massive late-stage bornite-rich ores.

Determination of metal (Bi)sulfide stability constants of Mn2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+ by voltammetric methods

Abstract: The stoichiometry as well as the conditional and thermodynamic stability constants for the (bi)sulfide complexes of the +2 cations of Mn, Fe, Ni, Co, Cu, and Zn have been determined by voltammetric methods in seawater and chloride solutions of varying ionic strength. Acid−base titrations allowed for the determination of the proton stoichiometry of the complexes. Mn, Fe, Ni, and Co form bisulfide, HS-, complexes of stoichiometry MSH+, M2(SH)3+, and M3(SH)5+, which are labile under diffusion control conditions, in seawater at pH values > 7. These complexes dissociate below pH = 7, releasing H2S from solution. Evidence for sulfide-rich complexes of form M(SH)2 was not found. Cu and Zn form sulfide, S2-, complexes of stoichiometry MS and M2S32-, which are inert (nonlabile) under diffusion control conditions, in seawater at pH values > 7. There is no evidence for metal-rich sulfide complexes of stoichiometry [MxS]2x-2 from the titration data. The M2S32- complexes are tetrameric structures (M4S6) with tetrahedr...

Kinetics of growth, substrate utilization and sulfide toxicity for propionate, acetate, and hydrogen utilizers in anaerobic systems

Abstract: Batch reactors and serum bottles were used to determine kinetics of growth, substrate utilization, and sulfide inhibition [dissolved sulfide (DS) and hydrogen sulfide (H2S)] in anaerobic systems fed propionate and sulfate. Thermodynamic analyses indicated six major groups of organisms were active in such systems: incomplete propionate oxidation by sulfate-reducing bacteria (SRB), propionate fermentation to acetate and hydrogen, acetate-oxidizing SRB, aceticlastic methanogenesis, hydrogenotrophic SRB, and hydrogenotrophic methanogens. Kinetic parameters determined for each of these groups were bacterial yield, decay coefficient, maximum specific substrate utilization coefficient, half-velocity constant, and inhibition coefficient (uncompetitive). Results indicated that the kinetic and thermodynamic advantages of acetate-utilizing SRB were erased by their sensitivity to sulfide toxicity. In addition, propionate fermenters were also very sensitive to sulfide toxicity. These results help to explain why methanogenesis from complex substrates occurs even in the presence of high concentrations of DS and H2S.

Trace elements in sulfide inclusions from Yakutian diamonds

Abstract: Sulfide inclusions in diamonds may provide the only pristine samples of mantle sulfides, and they carry important information on the distribution and abundances of chalcophile elements in the deep lithosphere. Trace-element abundances were measured by proton microprobe in >50 sulfide inclusions (SDI) from Yakutian diamonds; about half of these were measured in situ in polished plates of diamonds, providing information on the spatial distribution of compositional variations. Many of the diamonds were identified as peridotitic or eclogitic from the nature of coexisting silicate or oxide inclusions. Known peridotitic diamonds contain SDIs with Ni contents of 22–36%, consistent with equilibration between olivine, monosulfide solid solution (MSS) and sulfide melt, whereas SDIs in eclogitic diamonds contain 0–12% Ni. A group of diamonds without silicate or oxide inclusions has SDIs with 11–18% Ni, and may be derived from pyroxenitic parageneses. Eclogitic SDIs have lower Ni, Cu and Te than peridotitic SDIs; the ranges of the two parageneses overlap for Se, As and Mo. The Mo and Se contents range up to 700 and 300 ppm, respectively; the highest levels are found in peridotitic diamonds. Among the in-situ SDIs, significant Zn and Pb levels are found in those connected by cracks to diamond surfaces, and these elements reflect interaction with kimberlitic melt. Significant levels of Ru (30–1300 ppm) and Rh (10–170 ppm) are found in many peridotitic SDIs; SDIs in one diamond with wustite and olivine inclusions and complex internal structures have high levels of other platinum-group elements (PGEs) as well, and high chondrite-normalized Ir/Pd. Comparison with experimental data on element partitioning between crystals of monosulfide solid solution (MSS) and sulfide melts suggests that most of the inclusions in both parageneses were trapped as MSS, while some high-Cu SDIs with high Pd±Rh may represent fractionated sulfide melts. Spatial variations of SDI composition within single diamonds are consistent with growth histories shown by cathodoluminescence images, in which several stages of growth and resorption have occurred within magmatic environments that evolved during diamond formation.

Chemistry of ore-forming fluids and mineral formation rates in an active hydrothermal sulfide deposit on the Mid-Atlantic Ridge

Abstract: The chemical composition of diffuse effluent from the TAG hydrothermal mound, 26°N Mid-Atlantic Ridge, directly demonstrates that mixing of entrained seawater and high-temperature black smoker fluids leads to the precipitation of sulfides, silica, and anhydrite and to the zone refining of metals, including Cu, Zn, U, and the rare earth elements in an actively forming sulfide ore body. Rates of mineral formation deduced from these data are extremely rapid and are up to an order of magnitude greater for anhydrite (5–15 × 107 kg/yr) than for sulfides (106–107 kg/yr). Comparison with mineral inventories for TAG suggests that virtually all of the anhydrite in the TAG mound is contemporary, and confirms that the sulfide precipitated episodically during the history of mound growth and that much of it has been lost by oxidation and reworking.