WorldWideScience

Sample records for carbon sulfides

  1. Water purification by sulfide-containing activated carbon.

    Science.gov (United States)

    Oeste, F D; Haas, R; Kaminski, L

    2000-03-01

    We investigated a new kind of activated carbon named gaiasafe-Formstoff as an agent for powerful heavy metal reduction. This activated carbon contains highly dispersed sulfide compounds. Our investigations with lead containing wastewaters showed an outstanding metal sulfide precipitation power of the new agent. The lead reduction rates are independent of wastewater parameters like lead concentration and complexing agent concentration. Contacted as powder or as a fixed bed with wastewater gaiasafe-Formstoff showed the best cleaning capacity in comparison to all other agents tested. Investigations with gaiasafe-Formstoff about its ability to reduce the contents of further heavy metals in wastewater are under way. The gaiasafe-Formstoff reaction products with wastewater represent an energy-rich and raw material-rich resource when fed to metallurgical processes.

  2. Atmospheric measurements of carbonyl sulfide, dimethyl sulfide, and carbon disulfide using the electron capture sulfur detector

    Science.gov (United States)

    Johnson, James E.; Bates, Timothy S.

    1993-01-01

    Measurements of atmospheric dimethyl sulfide (DMS), carbonyl sulfide (COS), and carbon disulfide (CS2) were conducted over the Atlantic Ocean on board the NASA Electra aircraft during the Chemical Instrumentation Test and Evaluation (CITE 3) project using the electron capture sulfur detector (ECD-S). The system employed cryogenic preconcentration of air samples, gas chromatographic separation, catalytic fluorination, and electron capture detection. Samples collected for DMS analysis were scrubbed of oxidants with NaOH impregnated glass fiber filters to preconcentration. The detection limits (DL) of the system for COS, DMS, and CS2 were 5, 5, and 2 ppt, respectively. COS concentrations ranged from 404 to 603 ppt with a mean of 489 ppt for measurements over the North Atlantic Ocean (31 deg N to 41 deg N), and from 395 to 437 ppt with a mean of 419 ppt for measurements over the Tropical Atlantic Ocean (11 deg S to 2 deg N). DMS concentrations in the lower marine boundary layer, below 600-m altitude, ranged from below DL to 150 ppt from flights over the North Atlantic, and from 9 to 104 ppt over the Tropical Atlantic. CS2 concentrations ranged from below DL to 29 ppt over the North Atlantic. Almost all CS2 measurements over the Tropical Atlantic were below DL.

  3. Hydrogen attack - Influence of hydrogen sulfide. [on carbon steel

    Science.gov (United States)

    Eliezer, D.; Nelson, H. G.

    1978-01-01

    An experimental study is conducted on 12.5-mm-thick SAE 1020 steel (plain carbon steel) plate to assess hydrogen attack at room temperature after specimen exposure at 525 C to hydrogen and a blend of hydrogen sulfide and hydrogen at a pressure of 3.5 MN/sq m for exposure times up to 240 hr. The results are discussed in terms of tensile properties, fissure formation, and surface scales. It is shown that hydrogen attack from a high-purity hydrogen environment is severe, with the formation of numerous methane fissures and bubbles along with a significant reduction in the room-temperature tensile yield and ultimate strengths. However, no hydrogen attack is observed in the hydrogen/hydrogen sulfide blend environment, i.e. no fissure or bubble formation occurred and the room-temperature tensile properties remained unchanged. It is suggested that the observed porous discontinuous scale of FeS acts as a barrier to hydrogen entry, thus reducing its effective equilibrium solubility in the iron lattice. Therefore, hydrogen attack should not occur in pressure-vessel steels used in many coal gasification processes.

  4. When can Electrochemical Techniques give Reliable Corrosion Rates on Carbon Steel in Sulfide Media?

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel; Hemmingsen, Tor; Nielsen, Lars Vendelbo

    2005-01-01

    Effects of film formation on carbon steel in hydrogen sulfide media may corrupt corrosion rate monitoring by electrochemical techniques. Electrochemical data from hydrogen sulfide solutions, biological sulfide media and natural sulfide containing geothermal water have been collected and the process...... corrosion rates, but this effect may not be detected if rates are already overestimated. It is concluded that electrochemical techniques can be used for corrosion rate monitoring in som hydrogen sulfide media, but care must be taken when choosing the scan rates, and it is important to realize when direct...... in combination with ferrous sulfide corrosion products cover the steel surface. Corrosion rates can be overestimated by a factor of 10 to 100 with electrochemical techniques - both by linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS). Oxygen entering the system accelerates...

  5. Sulfide treatment to inhibit mercury adsorption onto activated carbon in carbon-in-pulp gold recovery circuits

    Energy Technology Data Exchange (ETDEWEB)

    Touro, F.J.; Lipps, D.A.

    1988-03-29

    A process for treating a mercury-contaminated, precious metal-containing ore slurry is described comprising: (a) reacting sulfide anions in an aqueous ore slurry of a mercury and precious metal-containing carbonaceous ore, and (b) conducting a simultaneous cyanide leach and carbon-in-pulp adsorption of the precious metal from the carbonaceous ore in the sulfide-containing ore slurry.

  6. Carbonyl Sulfide for Tracing Carbon Fluxes Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J. Elliott [Univ. of California, Merced, CA (United States); Berry, Joseph A. [Carnegie Inst. of Science, Stanford, CA (United States); Billesbach, Dave [Univ. of Nebraska, Lincoln, NE (United States); Torn, Margaret S [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zahniser, Mark [Aerodyne Research, Inc., Billerica, MA (United States); Seibt, Ulrike [Univ. of California, Los Angeles, CA (United States); Maseyk, Kadmiel [Pierre and Marie Curie Univ., Paris (France)

    2016-04-01

    The April-June 2012 campaign was located at the U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility Southern Great Plains (SGP) site Central Facility and had three purposes. One goal was to demonstrate the ability of current instrumentation to correctly measure fluxes of atmospheric carbonyl sulfide (COS). The approach has been describe previously as a critical approach to advancing carbon cycle science1,2, but requires further investigation at the canopy scale to resolve ecosystem processes. Previous canopy-scale efforts were limited to data rates of 1Hz. While 1 Hz measurements may work in a few ecosystems, it is widely accepted that data rates of 10 to 20 Hz are needed to fully capture the exchange of traces gases between the atmosphere and vegetative canopy. A second goal of this campaign was to determine if canopy observations could provide information to help interpret the seasonal double peak in airborne observations at SGP of CO2 and COS mixing ratios. A third goal was to detect potential sources and sinks of COS that must be resolved before using COS as a tracer of gross primary productivity (GPP).

  7. Regional-Scale Carbon Flux Partitioning Using Atmospheric Carbonyl Sulfide

    Science.gov (United States)

    Abu-Naser, M.; Campbell, J. E.; Berry, J. A.

    2011-12-01

    Simultaneous analysis of atmospheric concentrations of carbonyl sulfide (COS) and carbon dioxide (CO2) has been proposed as an approach to partitioning gross primary production and respiration fluxes at regional and global scales. The basis for this approach was that the observation and regional gradients in atmospheric CO2 are dominated by net ecosystem fluxes while regional gradients in atmospheric COS are dominated by GPP-related plant uptake. Here we investigate the spatial and temporal gradients in airborne COS and CO2 measurements in comparison to flux estimates from ecosystem models and eddy covariance methods over North America. The spatial gradients in the ecosystem relative uptake (ERU), the normalized ratio of COS and CO2 vertical gradients, were consistent with the theoretical relationship to flux estimates from ecosystem models and eddy covariance methods. The seasonality of the gross primary productivity flux estimates was consistent with airborne observations in the midwestern region but had mixed results in the southeastern region. Inter-annual changes in the ERU and regional drought index data suggested a potential relationship between drought stress and low ratios of gross primary production to net ecosystem exchange.

  8. Vibrational Spectroscopic Studies of Hydrogen, Carbon-Monoxide and Thiophene Adsorption on Ruthenium-Sulfide and Sulfided Ruthenium Catalysts.

    Science.gov (United States)

    Heise, William Herbert

    The "working surface" of ruthenium hydrodesulfurization (HDS) catalysts has been modeled by preadsorption of sulfur, carbon and carbon plus sulfur on Ru(0001). Adsorption and decomposition of thiophene over these surfaces have been investigated using TDS/TPRS, XPS and EELS. Thiophene is proposed to decompose via a three-step mechanism involving: (i) initial thiophene cracking at 120 K yielding surface sulfur and hydrocarbon species, (ii) hydrogen desorption near 230 K providing additional decomposition ensembles and (iii) continued decomposition to form "metallocycle -like" intermediates which retain EELS features similar to thiophene. Preadsorbed carbon or carbon plus sulfur are not as effective for passivation of the surface toward metallocycle formation as preadsorbed sulfur alone. This result is attributed to the fact that carbon deposited from butadiene annealed and decomposed at 700 K forms islands, while sulfur establishes a well-ordered superlattice on the surface. The decrease in metallocycle formation with increasing poison levels appears to explain HDS selectivity and specific activity trends observed in our laboratory from mildly sulfided (10% H_2S/H_2 , 673 K, 2h) ruthenium catalysts retaining submonolayers of sulfur. Incoherent inelastic neutron scattering (IINS) has been used to characterize hydrogen adsorption sites on ruthenium sulfide. Hydrogen resides on sulfur anions to form SH groups, yielding two non-degenerate bending modes at 600 and 710 cm^{-1}. Complementary hydrogen adsorption and H_2/D _2 exchange data suggest that the active sites for hydrogen adsorption may be coordinatively unsaturated S-S anion pairs. Comparison of CO adsorption on sulfided Ru/Al _2O_3 to sulfur precovered Ru(0001) reveals an adsorption site related to edge/corner atoms directly perturbed by sulfur, consistent with previous kinetic studies demonstrating higher specific activity for thiophene HDS over smaller ruthenium crystallites.

  9. Assaying the catalytic potential of transition metal sulfides for abiotic carbon fixation

    Science.gov (United States)

    Cody, G. D.; Boctor, N. Z.; Brandes, J. A.; Filley, T. R.; Hazen, R. M.; Yoder, H. S.

    2004-05-01

    A suite of nickel, cobalt, iron, copper, and zinc containing sulfides are assayed for the promotion of a model carbon fixation reaction with relevance to local reducing environments of the early Earth. The assay tests the promotion of hydrocarboxylation (the Koch reaction) wherein a carboxylic acid is synthesized via carbonyl insertion at a metal-sulfide-bound alkyl group. The experimental conditions are chosen for optimal assay, i.e., high reactant concentrations and pressures (200 MPa) to enhance chemisorption, and high temperature (250°C) to enhance reaction kinetics. All of the metal sulfides studied, with the exception CuS, promote hydrocarboxylation. Two other significant reactions involve the catalytic reduction of CO to form a surface-bound methyl group, detected after nucleophilic attack by nonane thiol to form methyl nonyl sulfide, and the formation of dinonyl sulfide via a similar reaction. Estimation of the catalytic turnover frequencies for each of the metal sulfides with respect to each of the primary reactions reveals that NiS, Ni 3S 2, and CoS perform comparably to commonly employed industrial catalysts. A positive correlation between the yield of primary product to NiS and Ni 3S 2 surface areas provides strong evidence that the reactions are surface catalytic in these cases. The sulfides FeS and Fe (1-x)S are unique in that they exhibit evidence of extensive dissolution, thus, complicating interpretation regarding heterogeneous vs. homogeneous catalysis. With the exception of CuS, each of the metal sulfides promotes reactions that mimic key intermediate steps manifest in the mechanistic details of an important autotrophic enzyme, acetyl-CoA synthase. The relatively high temperatures chosen for assaying purposes, however, are incompatible with the accumulation of thioesters. The results of this study support the hypothesis that transition metal sulfides may have provided useful catalytic functionality for geochemical carbon fixation in a prebiotic

  10. Catalytic effect of activated carbon on bioleaching of low-grade primary copper sulfide ores

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The catalytic effect of activated carbon on the bioleaching of low-grade primary copper sulfide ores using mixture of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans was investigated. The results show that the addition of activated carbon can greatly accelerate the rate and efficiency of copper dissolution from low-grade primary copper sulfide ores. The solution with the concentration of 3.0 g/L activated carbon is most beneficial to the dissolution of copper. The resting time of the mixture of activated carbon and ores has an impact on the bioleaching of low-grade primary copper sulfide ores. The 2 d resting time is most favorable to the dissolution of copper. The enhanced dissolution rate and efficiency of copper can be attributed to the galvanic interaction between activated carbon and chalcopyrite. The addition of activated carbon obviously depresses the dissolution of iron and the bacterial oxidation of ferrous ions in solution. The lower redox potentials are more favorable to the copper dissolution than the higher potentials for low-grade primary copper sulfide ores in the presence of activated carbon.

  11. Reliability of Electrochemical Techniques for Determining Corrosion Rates on Carbon Steel in Sulfide Media

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel; Hemmingsen, T.; Nielsen, Lars Vendelbo

    2007-01-01

    Effects of film formation on carbon steel in hydrogen sulfide (H2S) media may corrupt corrosion rate monitoring by electrochemical techniques. Electrochemical data from H2S solutions, biological sulfide media, and natural sulfide containing geothermal water have been collected, and the process...... if the biofilm in combination with ferrous sulfide corrosion products cover the steel surface. Corrosion rates can be overestimated by a factor of 10 to 100 with electrochemical techniques - both by linear polarization resistance (LPR) and electrochemicel impedance spectroscopy (EIS). Oxygen entering the system...... accelerates corrosion rates, but this effect may not be detected if rates are already overestimated. It is concluded that electrochemical techniques can be used for corrosion reate monitoring in some H2S media, but care must be taken in the choice of scan ratre; it is important to realize when direct...

  12. Effect of Additional Sulfide and Thiosulfate on Corrosion of Q235 Carbon Steel in Alkaline Solutions

    Directory of Open Access Journals (Sweden)

    Bian Li Quan

    2016-01-01

    Full Text Available This paper investigated the effect of additional sulfide and thiosulfate on Q235 carbon steel corrosion in alkaline solutions. Weight loss method, scanning electron microscopy (SEM equipped with EDS, X-ray photoelectron spectroscopy (XPS, and electrochemical measurements were used in this study to show the corrosion behavior and electrochemistry of Q235 carbon steel. Results indicate that the synergistic corrosion rate of Q235 carbon steel in alkaline solution containing sulfide and thiosulfate is larger than that of sulfide and thiosulfate alone, which could be due to redox reaction of sulfide and thiosulfate. The surface cracks and pitting characteristics of the specimens after corrosion were carefully examined and the corrosion products film is flake grains and defective. The main corrosion products of specimen induced by S2− and S2O32- are FeS, FeS2, Fe3O4, and FeOOH. The present study shows that the corrosion mechanism of S2− and S2O32- is different for the corrosion of Q235 carbon steel.

  13. Electrochemical properties of tungsten sulfide-carbon composite microspheres prepared by spray pyrolysis.

    Science.gov (United States)

    Choi, Seung Ho; Boo, Sung Jin; Lee, Jong-Heun; Kang, Yun Chan

    2014-01-01

    Tungsten sulfide (WS2)-carbon composite powders with superior electrochemical properties are prepared by a two-step process. WO3-carbon composite powders were first prepared by conventional spray pyrolysis, and they were then sulfidated to form WS2-carbon powders. Bare WS2 powders are also prepared by sulfidation of bare WO3 powders obtained by spray pyrolysis. Stacked graphitic layers could not be found in the bare WS2 and WS2-carbon composite powders. The amorphous bare WS2 and WS2-carbon composite powders have Brunauer-Emmett-Teller (BET) surface areas of 2.8 and 4 m(2) g(-1), respectively. The initial discharge and charge capacities of the WS2-carbon composite powders at a current density of 100 mA g(-1) are 1055 and 714 mA h g(-1), respectively, and the corresponding initial Coulombic efficiency is 68%. On the other hand, the initial discharge and charge capacities of the bare WS2 powders are 514 and 346 mA h g(-1), respectively. The discharge capacities of the WS2-carbon composite powders for the 2(nd) and 50(th) cycles are 716 and 555 mA h g(-1), respectively, and the corresponding capacity retention measured after first cycle is 78%.

  14. Is carbonyl sulfide a precursor for carbon disulfide in vegetation and soil? Interconversion of carbonyl sulfide and carbon disulfide in fresh grain tissues in vitro.

    Science.gov (United States)

    Ren, Y

    1999-05-01

    The interconversion of carbonyl sulfide (COS) and carbon disulfide (CS(2)) was studied in the roots and shoots of barley and chickpeas. Ratios of conversion gases, K, 40 h after the addition of COS or CS(2) are recorded. The proportion of COS converted to each of CS(2), CO, and H(2)S and the proportion of CS(2) converted to COS were greater in roots than in shoots. More COS was converted to CS(2) than CS(2) to COS in roots and shoots of barley and chickpeas. The amount of COS converted to H(2)S and CO was 8 times the amount converted to CS(2) in barley and 3-4 times the amount in chickpeas. Carbonyl sulfide may be a precursor for CS(2) in vegetation and soil, just as the reverse is true in the atmosphere. These two different results might form a cycle of COS and CS(2).

  15. Self-assembly of biomorphic carbon/sulfur microstructures in sulfidic environments

    Science.gov (United States)

    Cosmidis, Julie; Templeton, Alexis S.

    2016-09-01

    In natural and laboratory-based environments experiencing sustained counter fluxes of sulfide and oxidants, elemental sulfur (S0)--a key intermediate in the sulfur cycle--can commonly accumulate. S0 is frequently invoked as a biomineralization product generated by enzymatic oxidation of hydrogen sulfide and polysulfides. Here we show the formation of S0 encapsulated in nanometre to micrometre-scale tubular and spherical organic structures that self-assemble in sulfide gradient environments in the absence of any direct biological activity. The morphology and composition of these carbon/sulfur microstructures so closely resemble microbial cellular and extracellular structures that new caution must be applied to the interpretation of putative microbial biosignatures in the fossil record. These reactions between sulfide and organic matter have important implications for our understanding of S0 mineralization processes and sulfur interactions with organic carbon in the environment. They furthermore provide a new pathway for the synthesis of carbon-sulfur nanocomposites for energy storage technologies.

  16. Nitrogen reduction pathways in estuarine sediments: Influences of organic carbon and sulfide

    Science.gov (United States)

    Plummer, Patrick; Tobias, Craig; Cady, David

    2015-10-01

    Potential rates of sediment denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) were mapped across the entire Niantic River Estuary, CT, USA, at 100-200 m scale resolution consisting of 60 stations. On the estuary scale, denitrification accounted for ~ 90% of the nitrogen reduction, followed by DNRA and anammox. However, the relative importance of these reactions to each other was not evenly distributed through the estuary. A Nitrogen Retention Index (NIRI) was calculated from the rate data (DNRA/(denitrification + anammox)) as a metric to assess the relative amounts of reactive nitrogen being recycled versus retained in the sediments following reduction. The distribution of rates and accompanying sediment geochemical analytes suggested variable controls on specific reactions, and on the NIRI, depending on position in the estuary and that these controls were linked to organic carbon abundance, organic carbon source, and pore water sulfide concentration. The relationship between NIRI and organic carbon abundance was dependent on organic carbon source. Sulfide proved the single best predictor of NIRI, accounting for 44% of its observed variance throughout the whole estuary. We suggest that as a single metric, sulfide may have utility as a proxy for gauging the distribution of denitrification, anammox, and DNRA.

  17. Constraining surface carbon fluxes using in situ measurements of carbonyl sulfide and carbon dioxide

    Science.gov (United States)

    Berkelhammer, M.; Asaf, D.; Still, C.; Montzka, S.; Noone, D.; Gupta, M.; Provencal, R.; Chen, H.; Yakir, D.

    2014-02-01

    Understanding the processes that control the terrestrial exchange of carbon is critical for assessing atmospheric CO2 budgets. Carbonyl sulfide (COS) is taken up by vegetation during photosynthesis following a pathway that mirrors CO2 but has a small or nonexistent emission component, providing a possible tracer for gross primary production. Field measurements of COS and CO2 mixing ratios were made in forest, senescent grassland, and riparian ecosystems using a laser absorption spectrometer installed in a mobile trailer. Measurements of leaf fluxes with a branch-bag gas-exchange system were made across species from 10 genera of trees, and soil fluxes were measured with a flow-through chamber. These data show (1) the existence of a narrow normalized daytime uptake ratio of COS to CO2 across vascular plant species of 1.7, providing critical information for the application of COS to estimate photosynthetic CO2 fluxes and (2) a temperature-dependent normalized uptake ratio of COS to CO2 from soils. Significant nighttime uptake of COS was observed in broad-leafed species and revealed active stomatal opening prior to sunrise. Continuous high-resolution joint measurements of COS and CO2 concentrations in the boundary layer are used here alongside the flux measurements to partition the influence that leaf and soil fluxes and entrainment of air from above have on the surface carbon budget. The results provide a number of critical constraints on the processes that control surface COS exchange, which can be used to diagnose the robustness of global models that are beginning to use COS to constrain terrestrial carbon exchange.

  18. Hydrogen Sulfide Induced Carbon Dioxide Activation by Metal-Free Dual Catalysis.

    Science.gov (United States)

    Kumar, Manoj; Francisco, Joseph S

    2016-03-18

    The role of metal free dual catalysis in the hydrogen sulfide (H2S)-induced activation of carbon dioxide (CO2) and subsequent decomposition of resulting monothiolcarbonic acid in the gas phase has been explored. The results suggest that substituted amines and monocarboxylic type organic or inorganic acids via dual activation mechanisms promote both activation and decomposition reactions, implying that the judicious selection of a dual catalyst is crucial to the efficient C-S bond formation via CO2 activation. Considering that our results also suggest a new mechanism for the formation of carbonyl sulfide from CO2 and H2S, these new insights may help in better understanding the coupling between the carbon and sulfur cycles in the atmospheres of Earth and Venus.

  19. Decomposition kinetic study of nanostructured composites of poly (phenylene sulfide) reinforced with carbon nanotubes

    OpenAIRE

    Bruno Ribeiro; Edson C. Botelho; Michelle L. Costa

    2014-01-01

    The aim of this work is to obtain nanostructured composites of poly (phenylene sulfide), PPS, reinforced with multiwalled carbon nanotubes, MWCNT, by melt mixing technique and further characterization of their morphological and thermal properties. Transmission Electron Microscopy analysis was carried out to evaluate the quality of MWCNT dispersion throughout the PPS matrix. Thermogravimetry shows an increase in the maximum degradation temperature by the addition of the nanofiller to the polym...

  20. Carbonyl sulfide exchange in soils for better estimates of ecosystem carbon uptake

    OpenAIRE

    M. E. Whelan; Hilton, T. W.; Berry, J. A.; M. Berkelhammer; A. R. Desai; Campbell, J. E.

    2015-01-01

    Carbonyl sulfide (COS) measurements are one of the emerging tools to better quantify gross primary production (GPP), the largest flux in the global carbon cycle. COS is a gas with a similar structure to CO2; COS uptake is thought to be a proxy for GPP. However, soils are a potential source or sink of COS. This study presents a framework for understanding soil-COS interactions. Excluding wetlands, most of the few observations of isolated soils that have been ...

  1. Carbonyl sulfide exchange in soils for better estimates of ecosystem carbon uptake

    OpenAIRE

    Whelan, Mary E.; Hilton, Timothy W; Berry, Joseph A; Berkelhammer, Max; Desai, Ankur R; Campbell, J. Elliott

    2016-01-01

    Carbonyl sulfide (COS) measurements are one of the emerging tools to better quantify gross primary production (GPP), the largest flux in the global carbon cycle. COS is a gas with a similar structure to CO2; COS uptake is thought to be a proxy for GPP. However, soils are a potential source or sink of COS. This study presents a framework for understanding soil–COS interactions. Excluding wetlands, most of the few observations of isolated soils that have been made show smal...

  2. Mineralogy and Geochemical Processes of Carbonate Mineral-rich Sulfide Mine Tailings, Zimapan, Mexico

    Science.gov (United States)

    McClure, R. J.; Deng, Y.; Loeppert, R.; Herbert, B. E.; Carrillo, R.; Gonzalez, C.

    2009-12-01

    Mining for silver, lead, zinc, and copper in Zimapan, Hidalgo State, Mexico has been ongoing since 1576. High concentrations of heavy metals have been found in several mine tailing heaps in the Zimapan area, with concentrations of arsenic observed as high as 28,690 mg/kg and levels of Pb as high as 2772 mg/kg. Unsecured tailings heaps and associated acid mine drainage has presented tremendous problems to revegetation, water quality, and dust emission control in the Zimapan area. Although acid mine drainage problems related to weathering of sulfide minerals have been extensively studied and are well known, the weathering products of sulfides in areas with a significant presence of carbonate minerals and their effect on the mobility of heavy metals warrant further study. Carbonate minerals are expected to neutralize sulfuric acid produced from weathering of sulfide minerals, however, in the Zimapan area localized areas of pH as low as 1.8 were observed within carbonate mineral-rich tailing heaps. The objectives of this study are to characterize (1) the heavy metal-containing sulfide minerals in the initial tailing materials, (2) the intermediate oxidation products of sulfide minerals within the carbonate-rich tailings, (3) chemical species of heavy metals within pH gradients between 1.8 and 8.2, the approximate natural pH of limestone, and (4) the mobility of soluble and colloidal heavy metals and arsenic within the carbonate-rich tailings. Representative mine tailings and their intermediate oxidation products have been sampled from the Zimapan area. Mineralogical characterization will be conducted with X-ray diffraction, infrared spectroscopy, electron microscopes and microprobes, and chemical methods. Chemical species will be extracted by selective dissolution methods. Preliminary results have identified calcite as the dominant mineral in the tailing heaps with a pH of 7, suggesting non-equilibrium with the acidic weathering products. Other minerals identified in

  3. Combining electrospinning and sputtering to improve rechargeable lithium battery cathodes: coating carbon fibre felt with nickel sulfide

    Science.gov (United States)

    Lee, Dong Kyu; Ryu, Ho Suk; Ahn, Chi Won; Jeon, Hwan-Jin

    2016-11-01

    Various nickel sulfide nanostructures have been developed for the fabrication of high surface area electrodes for rechargeable lithium batteries. In this study, we fabricated a nickel sulfide covered carbon fibre felt with high uniformity, high density, and large area for cathode materials for use in rechargeable lithium batteries, by using a combined electrospinning and sputtering deposition technique. In particular, the nickel sulfide/carbon fibre felt is a multi-functional material that can act as a conducting electrode itself without the use of binders and conductive materials owing to the high conductivity of the interlinked carbon fibre structures. A Li/nickel sulfide cell with current density of 100 mA g-1 exhibits good cycle performance and high first discharge capacity (970.46 mAh g-1) and good coulombic efficiency of 99% at 20 cycles. This electrode has good structural and electrochemical properties and has a potential to be commercialized when the properties are matured.

  4. Ammonia, hydrogen sulfide, carbon dioxide and particulate matter emissions from California high-rise layer houses

    Science.gov (United States)

    Lin, X.-J.; Cortus, E. L.; Zhang, R.; Jiang, S.; Heber, A. J.

    2012-01-01

    Ammonia and hydrogen sulfide are hazardous substances that are regulated by the U.S. Environmental Protection Agency through community right-to-know legislation (EPCRA, EPA, 2011). The emissions of ammonia and hydrogen sulfide from large commercial layer facilities are of concern to legislators and nearby neighbors. Particulate matter (PM 10 and PM 2.5) released from layer houses are two of seven criteria pollutants for which EPA has set National Ambient Air Quality Standards as required by the Clean Air Act. Therefore, it is important to quantify the baseline emissions of these pollutants. The emissions of ammonia, hydrogen sulfide, carbon dioxide and PM from two California high-rise layer houses were monitored for two years from October 2007 to October 2009. Each house had 32,500 caged laying hens. The monitoring site was setup in compliance with a U.S. EPA-approved quality assurance project plan. The results showed the average daily mean emission rates of ammonia, hydrogen sulfide and carbon dioxide were 0.95 ± 0.67 (standard deviation) g d -1 bird -1, 1.27 ± 0.78 mg d -1 bird -1 and 91.4 ± 16.5 g d -1 bird -1, respectively. The average daily mean emission rates of PM 2.5, PM 10 and total suspended particulate (TSP) were 5.9 ± 12.6, 33.4 ± 27.4, and 78.0 ± 42.7 mg d -1 bird -1, respectively. It was observed that ammonia emission rates in summer were lower than in winter because the high airflow stabilized the manure by drying it. The reductions due to lower moisture content were greater than the increases due to higher temperature. However, PM 10 emission rates in summer were higher than in winter because the drier conditions coupled with higher internal air velocities increased PM 10 release from feathers, feed and manure.

  5. An Enzymatic Glucose Sensor Composed of Carbon-Coated Nano Tin Sulfide

    Science.gov (United States)

    Chung, Ren-Jei; Wang, An-Ni; Peng, Shiuan-Ying

    2017-01-01

    In this study, a biosensor, based on a glucose oxidase (GOx) immobilized, carbon-coated tin sulfide (SnS) assembled on a glass carbon electrode (GCE) was developed, and its direct electrochemistry was investigated. The carbon coated SnS (C-SnS) nanoparticle was prepared through a simple two-step process, using hydrothermal and chemical vapor deposition methods. The large reactive surface area and unique electrical potential of C-SnS could offer a favorable microenvironment for facilitating electron transfer between enzymes and the electrode surface. The structure and sensor ability of the proposed GOx/C-SnS electrode were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), and cyclic voltammetry study (CV).

  6. Stable Isotope Measurements of Carbon Dioxide, Methane, and Hydrogen Sulfide Gas Using Frequency Modulation Spectroscopy

    Science.gov (United States)

    Nowak-Lovato, K.

    2014-12-01

    Seepage from enhanced oil recovery, carbon storage, and natural gas sites can emit trace gases such as carbon dioxide, methane, and hydrogen sulfide. Trace gas emission at these locations demonstrate unique light stable isotope signatures that provide information to enable source identification of the material. Light stable isotope detection through surface monitoring, offers the ability to distinguish between trace gases emitted from sources such as, biological (fertilizers and wastes), mineral (coal or seams), or liquid organic systems (oil and gas reservoirs). To make light stable isotope measurements, we employ the ultra-sensitive technique, frequency modulation spectroscopy (FMS). FMS is an absorption technique with sensitivity enhancements approximately 100-1000x more than standard absorption spectroscopy with the advantage of providing stable isotope signature information. We have developed an integrated in situ (point source) system that measures carbon dioxide, methane and hydrogen sulfide with isotopic resolution and enhanced sensitivity. The in situ instrument involves the continuous collection of air and records the stable isotope ratio for the gas being detected. We have included in-line flask collection points to obtain gas samples for validation of isotopic concentrations using our in-house isotope ratio mass spectroscopy (IRMS). We present calibration curves for each species addressed above to demonstrate the sensitivity and accuracy of the system. We also show field deployment data demonstrating the capabilities of the system in making live dynamic measurements from an active source.

  7. The Anarraaq Zn-Pb-Ag and barite deposit, northern Alaska: Evidence for replacement of carbonate by barite and sulfides

    Science.gov (United States)

    Kelley, K.D.; Dumoulin, J.A.; Jennings, S.

    2004-01-01

    The Anarraaq deposit in northern Alaska consists of a barite body, estimated to be as much as 1 billion metric tons, and a Zn-Pb-Ag massive sulfide zone with an estimated resource of about 18 Mt at 18 percent Zn, 5.4 percent Pb, and 85 g/t Ag. The barite and sulfide minerals are hosted by the uppermost part of the Mississippian Kuna Formation (Ikalukrok unit) that consists of carbonaceous and siliceous mudstone or shale interbedded with carbonate. The amount of interbedded carbonate in the Anarraaq deposit is atypical of the district as a whole, comprising as much as one third of the section. The total thickness of the Ikalukrok unit is considerably greater in the area of the deposit (210 to almost 350 m) than to the north and south (maximum of 164 m). The mineralized zone at Anarraaq is lens shaped and has a relatively flat top and a convex base. It also ranges greatly in thickness, from a few meters to more than 100 m. Textures of some of the carbonate layers are distinctive, consisting of nodules within siliceous mudstone or layers interbedded with shale. Many of the layers contain calcitized sponge spicules or radiolarians in a carbonate matrix. Textures of barite and sulfide minerals mimic those of carbonate and provide unequivocal evidence that replacement of precursor carbonate was an important process. Barite and sulfide textures include either nodular, bladed grains of various sizes that resemble spicules (observed only with iron sulfides) or well-rounded forms that are replaced radiolarians. Mineralization at Anarraaq probably occurred in a fault-bounded Carboniferous basin during early diagenesis in the shallow subsurface. The shape and size of the mineralized body suggest that barite and sulfides replaced calcareous mass flow deposits in a submarine channel. The distribution of biogenic and/or early diagenetic silica may have served as impermeable barriers to the fluids, thereby focusing and controlling fluid flow through unreplaced carbonate layers

  8. Stable isotopes of carbon dioxide in soil gas over massive sulfide mineralization at Crandon, Wisconsin

    Science.gov (United States)

    Alpers, C.N.; Dettman, D.L.; Lohmann, K.C.; Brabec, D.

    1990-01-01

    Stable isotope ratios of oxygen and carbon were determined for CO2 in soil gas in the vicinity of the massive sulfide deposit at Crandon, Wisconsin with the objective of determining the source of anomalously high CO2 concentrations detected previously by McCarthy et al. (1986). Values of ??13C in soil gas CO2 from depths between 0.5 and 1.0 m were found to range from -12.68??? to -20.03??? (PDB). Organic carbon from the uppermost meter of soil has ??13C between -24.1 and -25.8??? (PDB), indicating derivation from plant species with the C3 (Calvin) type of photosynthetic pathway. Microbial decomposition of the organic carbon and root respiration from C3 and C4 (Hatch-Slack) plants, together with atmospheric CO2 are the likely sources of carbon in soil gas CO2. Values of ??18O in soil-gas CO2 range from 32 to 38??? (SMOW). These ??18O values are intermediate between that calculated for CO2 gas in isotopic equilibrium with local groundwaters and that for atmospheric CO2. The ??18O data indicate that atmospheric CO2 has been incorporated by mixing or diffusion. Any CO2 generated by microbial oxidation of organic matter has equilibrated its oxygen isotopes with the local groundwaters. The isotopic composition of soil-gas CO2 taken from directly above the massive sulfide deposit was not distinguishable from that of background samples taken 1 to 2 km away. No enrichment of the ??13C value of soil-gas CO2 was observed, contrary to what would be expected if the anomalous CO2 were derived from the dissolution of Proterozoic marine limestone country rock or of Paleozoic limestone clasts in glacial till. Therefore, it is inferred that root respiration and decay of C3 plant material were responsible for most CO2 generation both in the vicinity of the massive sulfide and in the "background" area, on the occasion of our sampling. Interpretation of our data is complicated by the effects of rainfall, which significantly reduced the magnitude of the CO2 anomaly. Therefore, we cannot

  9. Carbon dioxide and hydrogen sulfide associations with regional bacterial diversity patterns in microbially induced concrete corrosion.

    Science.gov (United States)

    Ling, Alison L; Robertson, Charles E; Harris, J Kirk; Frank, Daniel N; Kotter, Cassandra V; Stevens, Mark J; Pace, Norman R; Hernandez, Mark T

    2014-07-01

    The microbial communities associated with deteriorating concrete corrosion fronts were characterized in 35 samples taken from wastewater collection and treatment systems in ten utilities. Bacterial communities were described using Illumina MiSeq sequencing of the V1V2 region of the small subunit ribosomal ribonucleic acid (SSU-rRNA) gene recovered from fresh corrosion products. Headspace gas concentrations (hydrogen sulfide, carbon dioxide, and methane), pore water pH, moisture content, and select mineralogy were tested for correlation to community outcomes and corrosion extent using pairwise linear regressions and canonical correspondence analysis. Corroding concrete was most commonly characterized by moisture contents greater than 10%, pore water pH below one, and limited richness (100 ppm) and carbon dioxide (>1%) gases, conditions which also were associated with low diversity biofilms dominated by members of the acidophilic sulfur-oxidizer genus Acidithiobacillus.

  10. Microfabric analysis of Mn-carbonate laminae deposition and Mn-sulfide formation in the Gotland Deep, Baltic Sea

    Science.gov (United States)

    Burke, Ian T.; Kemp, Alan E. S.

    2002-05-01

    The manganese carbonate deposits of the anoxic Littorina sediments of the Gotland Deep have been commonly related to the periodic renewal of deep water by inflowing saline water from the North Sea. The use of scanning electron microscopy-based techniques allows identification of small-scale sedimentary and geochemical features associated with Mn-carbonate laminae, which has significant implications for models of Mn-carbonate formation. Varves occurring in the Littorina sequence contain up to four laminae that may be placed in a seasonal cycle, and kutnahorite laminae occur within varves only as a winter-early spring deposit. This kutnahorite laminae seasonality is in agreement with the seasonal distribution of major Baltic inflow events recorded in historical records, and a direct causal link between inflows and kutnahorite deposition is implied. Benthic foraminifera tests are found to be heavily encrusted in kutnahorite, implying that benthic recolonization during oxidation events occurs concurrently with kutnahorite formation. The relatively common occurrence of small (50 to 100 μm) hexagonal γ-Mn-sulfide pseudomorphs, associated with 13% of kutnahorite laminae studied, is reported in Gotland Deep sediments for the first time. Although Mn-sulfide crystals are not usually preserved in the sediment, the discovery of Mn-sulfide pseudomorphs suggests that initial formation of Mn-sulfide in the Gotland Deep may occur much more commonly during the process of kutnahorite formation than previous reports of Mn-sulfide occurrence have implied.

  11. Phosphorus mobilization by sulfide oxidation in carbonate sediments from seagrass and unvegetated sites in the US Virgin Islands

    DEFF Research Database (Denmark)

    Jensen, Henning; Pedersen, Ole; Koch, M. R.;

    oxidation, as well as metabolic acids from aerobic respiration, has the potential to mobilize solid phase phosphorus (P) pools in support of seagrass nutrition. Fresh sediments from four US Virgin Islands sites were modestly acidified to near-neutral pH in slurries. Following sulfuric acid amendments......PHOSPHORUS MOBILIZATION BY SULFIDE OXIDATION IN CARBONATE SEDIMENTS FROM SEAGRASS AND UNVEGETATED SITES IN THE US VIRGIN ISLANDS Sulfide produced by sulfate reduction (SR) can be oxidized by seagrass root O2 flux in shallow carbonate sediments low in Fe. The sulfuric acid produced from sulfide......, the mobilized P pools in the slurry water and the sediment-adsorbed pools were quantified. P mobilization rates in the field were also calculated using field estimates of SR rates applying 35SO43-. Phosphorus release was significantly higher in seagrass than bare sediment, and at sites close to anthropogenic...

  12. Measurement of low concentration and nano-quantity hydrogen sulfide in sera using unfunctionalized carbon nanotubes

    Science.gov (United States)

    Wu, X. C.; Zhang, W. J.; Sammynaiken, R.; Meng, Q. H.; Wu, D. Q.; Yang, Q.; Yang, W.; Zhang, Edwin M.; Wang, R.

    2009-10-01

    Hydrogen sulfide (H2S) is produced in small amounts by certain cells in the mammalian body and has a number of biological functions. H2S gas naturally produced by the body is not simply a toxic gas; it could be a vascular dilator and play a physiological role in regulating cardiovascular functions. In order to know the effects of H2S, it is necessary to accurately know its concentrations in the body. Conventional measurement methods have their limitations concerning the small amount and low concentration of H2S in the body. A new paradigm of using carbon nanotubes in H2S measurement expresses its potential. However, the influence of proteins in the mammalian body must be studied in the measurement of H2S by carbon nanotubes. In this paper, we demonstrate a successful measurement of low concentration (20 µM) and nano-quantity (0.5 µg) H2S in the serum by using carbon nanotubes and further with the fluorescence of confocal laser scanning microscopy and the luminescence of Raman microscopy. Statistical analysis of the experimental data shows that the relationship between concentrations and intensities is linear, which thus makes the carbon nanotube sensor highly promising for the measurement of H2S in sera.

  13. Removal of hydrogen sulfide and sulfur dioxide by carbons impregnated with triethylenediamine.

    Science.gov (United States)

    Wu, Li-Chun; Chang, Tsu-Hua; Chung, Ying-Chien

    2007-12-01

    Activated carbon (AC) adsorption has long been considered to be a readily available technology for providing protection against exposure to acutely toxic gases. However, ACs without chemical impregnation have proven to be much less efficient than impregnated ACs in terms of gas removal. The impregnated ACs in current use are usually modified with metalloid impregnation agents (ASC-carbons; copper, chromium, or silver) to simultaneously enhance the chemical and physical properties of the ACs in removing specific poisonous gases. These metalloid agents, however, can cause acute poisoning to both humans and the environment, thereby necessitating the search for organic impregnation agents that present a much lower risk. The aim of the study reported here was to assess AC or ASC-carbon impregnated with triethylenediamine (TEDA) in terms of its adsorption capability for simulated hydrogen sulfide (H2S) and sulfur dioxide (SO2) gases. The investigation was undergone in a properly designed laboratory-scale and industrial fume hood evaluation. Using the system reported here, we obtained a significant adsorption: the removal capability for H2S and SO2 was 375 and 229 mg/g-C, respectively. BET measurements, element analysis, scanning electron microscopy, and energy dispersive spectrometry identified the removal mechanism for TEDA-impregnated AC to be both chemical and physical adsorption. Chemical adsorption and oxidation were the primary means by which TEDA-impregnated ASC-carbons removed the simulated gases.

  14. Carbonyl sulfide as an inverse tracer for biogenic organic carbon in gas and aerosol phases

    Science.gov (United States)

    de Gouw, J. A.; Warneke, C.; Montzka, S. A.; Holloway, J. S.; Parrish, D. D.; Fehsenfeld, F. C.; Atlas, E. L.; Weber, R. J.; Flocke, F. M.

    2009-03-01

    Carbonyl sulfide (COS) is a long-lived trace gas in the atmosphere with an oceanic source and a surface sink through the uptake by vegetation and soils. We demonstrate the use of COS as an inverse tracer for the impact of biogenic emissions on an air mass including the formation of secondary organic aerosol (SOA). Using airborne data from the summer of 2004 over the northeastern U.S., we find that air masses with reduced COS in the continental boundary layer had on average higher mixing ratios of biogenic VOCs (isoprene, monoterpenes, methanol) and their photo-oxidation products (methacrolein, methyl vinyl ketone, methyl furan and MPAN, a peroxyacyl nitrate derived from isoprene). Measurements of water-soluble organic carbon were only weakly correlated with COS, indicating that SOA formation from biogenic precursors was a small contribution to the total.

  15. Role of black carbon electrical conductivity in mediating hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) transformation on carbon surfaces by sulfides.

    Science.gov (United States)

    Xu, Wenqing; Pignatello, Joseph J; Mitch, William A

    2013-07-01

    Recent research has demonstrated that black carbons catalyze the transformation of a range of nitrated explosives sorbed to the carbon surfaces in the presence of sulfides. Although surface oxygenated functional groups, particularly quinones, and electrical conductivity have both been hypothesized to promote these reactions, the importance of these properties has not been tested. In this work, the importance of electrical conductivity was addressed by producing chars of increasing electrical conductivity via pyrolysis of wood shavings at increasing temperature. The reactivity of chars with respect to transformation of the explosive RDX in the presence of sulfides correlated with electrical conductivity. Oxygenated functional groups were apparently not involved, as demonstrated by the elimination of reactivity of an activated carbon after ozone treatment or sorption of model quinones to the activated carbon surface. Although RDX transformation correlated with char electrical conductivity, no RDX transformation was observed when RDX was physically separated from sulfides but electrically connected through an electrochemical cell. RDX transformation occurred in the presence of a surface-associated sulfur species. The correlation with char electrical conductivity suggests that sulfides are oxidized on carbon surfaces to products that serve as potent nucleophiles promoting RDX transformation.

  16. Effects of Sodium Thiosulfate and Sodium Sulfide on the Corrosion Behavior of Carbon Steel in an MDEA-Based CO2 Capture Process

    Science.gov (United States)

    Emori, W.; Jiang, S. L.; Duan, D. L.; Zheng, Y. G.

    2016-12-01

    The corrosion behavior of carbon steel has been tested in the presence of sodium thiosulfate and sodium sulfide in an MDEA-based CO2 capture system using electrochemical methods, weight loss measurements and surface analysis. The results of electrochemical measurements revealed that both thiosulfate and sulfide showed corrosion resistance properties to carbon steel corrosion. The corrosion resistance for the system with thiosulfate increased with concentration, while the system with sulfide yielded better corrosion resistance to carbon steel at lower concentrations as increase in sulfide concentration decreased the corrosion resistance. The corrosion inhibition behaviors for both systems at 0.05 M salt concentrations were confirmed by weight loss measurement, and the solution with sodium sulfide exhibited a better inhibition with time.

  17. Effects of Sodium Thiosulfate and Sodium Sulfide on the Corrosion Behavior of Carbon Steel in an MDEA-Based CO2 Capture Process

    Science.gov (United States)

    Emori, W.; Jiang, S. L.; Duan, D. L.; Zheng, Y. G.

    2017-01-01

    The corrosion behavior of carbon steel has been tested in the presence of sodium thiosulfate and sodium sulfide in an MDEA-based CO2 capture system using electrochemical methods, weight loss measurements and surface analysis. The results of electrochemical measurements revealed that both thiosulfate and sulfide showed corrosion resistance properties to carbon steel corrosion. The corrosion resistance for the system with thiosulfate increased with concentration, while the system with sulfide yielded better corrosion resistance to carbon steel at lower concentrations as increase in sulfide concentration decreased the corrosion resistance. The corrosion inhibition behaviors for both systems at 0.05 M salt concentrations were confirmed by weight loss measurement, and the solution with sodium sulfide exhibited a better inhibition with time.

  18. Removals of aqueous sulfur dioxide and hydrogen sulfide using CeO2-NiAl-LDHs coating activated carbon and its mix with carbon nano-tubes

    KAUST Repository

    Li, Jing

    2015-07-01

    Ce-doped NiAl/layered double hydroxide was coated at activated carbon by urea hydrolysis method (CeO2-NiAl-LDHs/AC) in one pot, which was characterized by X-ray diffraction, infrared spectra, field emission scanning electron microscope and electrochemical techniques. CeO2-NiAl-LDHs/AC shows good uptake for aqueous sulfur dioxide (483.09mg/g) and hydrogen sulfide (181.15mg/g), respectively at 25°C. Meanwhile, the electrochemical removals of aqueous sulfur dioxide and hydrogen sulfide were respectively investigated at the mix of CeO2-NiAl-LDHs/AC and carbon nano-tubes modified homed paraffin-impregnated electrode. Both sulfur dioxide and hydrogen sulfide could be effectively oxidized to sulfuric acid at 1.0V in alkaline aqueous solution. © 2015 Elsevier B.V.

  19. Enriching distinctive microbial communities from marine sediments via an electrochemical-sulfide-oxidizing process on carbon electrodes

    Directory of Open Access Journals (Sweden)

    Shiue-Lin eLi

    2015-02-01

    Full Text Available Sulfide is a common product of marine anaerobic respiration, and a potent reactant biologically and geochemically. Here we demonstrate the impact on microbial communities with the removal of sulfide via electrochemical methods. The use of differential pulse voltammetry revealed that the oxidation of soluble sulfide was seen at + mV (vs. SHE at all pH ranges tested (from pH = 4 to 8, while non-ionized sulfide, which dominated at pH = 4 was poorly oxidized via this process. Two mixed cultures (CAT and LA were enriched from two different marine sediments (from Catalina Island, CAT; from the Port of Los Angeles, LA in serum bottles using a seawater medium supplemented with lactate, sulfate, and yeast extract, to obtain abundant biomass. Both CAT and LA cultures were inoculated in electrochemical cells (using yeast-extract-free seawater medium as an electrolyte equipped with carbon-felt electrodes. In both cases, when potentials of +630 or 130 mV (vs. SHE were applied, currents were consistently higher at +630 then at 0 mV, indicating more sulfide being oxidized at the higher potential. In addition, higher organic-acid and sulfate conversion rates were found at +630 mV with CAT, while no significant differences were found with LA at different potentials. The results of microbial-community analyses revealed a decrease in diversity for both CAT and LA after electrochemical incubation. In addition, some bacteria (e.g., Clostridium and Arcobacter not well known to be capable of extracellular electron transfer, were found to be dominant in the electrochemical cells. Thus, even though the different mixed cultures have different tolerances for sulfide, electrochemical-sulfide removal can lead to major population changes.

  20. Carbonyl sulfide (COS) as a tracer to constrain surface carbon fluxes

    Science.gov (United States)

    Yakir, Dan; Berkelhammer, Max; Miller, John; Montzka, Steve; Chen, Huilin

    2014-05-01

    provide additional constraints on the differential responses of photosynthesis and respiration, such as associated with C3 and C4 vegetation. Developing the use of COS as a powerful tracer of photosynthetic CO2 fluxes at all scales can help improve prediction of future responses of the terrestrial biosphere to changing environmental conditions. Key words Carbonyl sulfide, COS, Carbonic anhydrase, CA, ecosystem respiration, GPP, Biosphere-atmosphere interactions, soil COS uptake. References Asaf D, Rotenberg E, Tatarinov T, Dicken U, Montzka SA & Yakir D (2013) Ecosystem photosynthesis inferred from carbonyl sulfide flux measurements. Nature GeoScience, 6, 186-190; DOI: 10.1038/NGEO1730 Berry J, Wolf A, Campbell E, Baker I, Blake N, Blake D, Denning AS, Kawa SR, Montzka SA, Seibt UY, Stimler K, Yakir D Zhu Z (2013) A coupled model of the global cycles of carbonyl sulfide and CO2: A possible new window on the carbon cycle. J. Geophys. Res.: Biogeochem. 118, doi 10.1002/jgrg.20068, 2013 Stimler K, Berry JA, Montzka S, Yakir D (2011) Association between COS uptake and 18D during gas exchange in C3 and C4 leaves. Plant Physiol. Doi 10.1104/pp.111.176578

  1. Observations of the uptake of carbonyl sulfide (COS by trees under elevated atmospheric carbon dioxide concentrations

    Directory of Open Access Journals (Sweden)

    L. Sandoval-Soto

    2012-02-01

    Full Text Available Global change affects ecosystems to adapt to elevated atmospheric concentrations of carbon dioxide (CO2. We understand that carbonyl sulfide (COS, a trace gas which is involved in building up the stratospheric sulfate aerosol layer, is taken up by vegetation with the same triad of the enzmyes which are metabolizing the CO2, i.e. Ribulose-1,5-bisphosphate Carboxylase-Oxygenase (Rubisco, Phosphoenolpyruvate Carboxylase (PEP-Co and carbonic anhydrase (CA. Therefore, we discuss a physiological/biochemical adaptation of these enzymes to affect the sink strength of vegetation for COS. We investigated the adaption of two European tree species, Fagus sylvatica and Quercus ilex, grown inside chambers under elevated CO2 and determined the exchange characteristics and the content of CA after a 1–2 yr period of adaption from 350 ppm to 800 ppm CO2. We could demonstrate that the COS compensation point, the CA activity and the deposition velocities may change and cause a decrease of the COS uptake by plant ecosystems. As a consequence, the atmospheric COS level may rise leading to higher input of this trace gas into the stratosphere and causing a higher energy reflection by the stratospheric sulfur aerosol into space, thus counteracting the direct radiative forcing by the tropospheric COS.

  2. Self-assembly of biomorphic carbon/sulfur microstructures in sulfidic environments

    OpenAIRE

    Cosmidis, Julie; Templeton, Alexis S.

    2016-01-01

    In natural and laboratory-based environments experiencing sustained counter fluxes of sulfide and oxidants, elemental sulfur (S0)—a key intermediate in the sulfur cycle—can commonly accumulate. S0 is frequently invoked as a biomineralization product generated by enzymatic oxidation of hydrogen sulfide and polysulfides. Here we show the formation of S0 encapsulated in nanometre to micrometre-scale tubular and spherical organic structures that self-assemble in sulfide gradient environments in t...

  3. Quantifying Carbon-Climate Processes at the Regional Scale Using Atmospheric Carbonyl Sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Elliott [Univ. of California, Merced, CA (United States); Berry, Joe [Carnegie Inst. of Washington, Washington, DC (United States); Torn, Margaret [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); David, Billesbach [Univ. of Nebraska, Lincoln, NE (United States); Seibt, Ulrike [Univ. of California, Los Angeles, CA (United States)

    2013-10-08

    Atmospheric carbonyl sulfide (COS) analysis has the potentially transformative capability for partitioning the regional carbon flux into respiration and photosynthesis components. This emerging approach is based on the observation that continental atmospheric CO2 gradients are dominated by net ecosystem fluxes while continental atmospheric COS gradients are dominated by photosynthesis-related plant uptake. Regional flux partitioning represents a critical knowledge gap due to a lack of robust methods for regional-scale flux partitioning and large uncertainties in forecasting carbon-climate feedbacks. Our completed project characterized the relationship between COS and CO2 surface fluxes using a novel measurement and modeling system in a winter wheat field at the U.S. Department of Energy?s Atmospheric and Radiation Measurement program Central Facility (DOE-ARM CF). The scope of this project included canopy flux measurements, soil flux measurements, regional atmospheric modeling, and analysis of COS and CO2 airborne observations at SGP. Three critical discoveries emerged from this investigation: (1) the new measurement system provided the first field evidence of a robust relationship between COS leaf fluxes and GPP; (2) a previously unknown seasonal soil source of COS was observed and characterized; (3) the regional atmospheric analysis of airborne measurements provided the first COS-based constraints on GPP parameterizations used in earth systems models. Dissemination of these results includes three publications [Billesbach et al., In Press; Campbell et al., In Preparation; Seibt et al., In Review], three presentations at the AGU Fall Meeting (2012), and four invited presentations to department seminars. We have leveraged this foundational project to continue our work on understanding carbon cycle processes at large scales through one funded project (DOE Lab Fee, 2012-2015) and one proposal that is under review (DOE/NASA/USDA/NOAA, 2014-2016).

  4. Different distribution of in-situ thin carbon layer in hollow cobalt sulfide nanocages and their application for supercapacitors

    Science.gov (United States)

    Jin, Meng; Lu, Shi-Yu; Ma, Li; Gan, Meng-Yu; Lei, Yao; Zhang, Xiu-Ling; Fu, Gang; Yang, Pei-Shu; Yan, Mao-Fa

    2017-02-01

    Recently, cobalt sulfides emerge as a candidate for energy reserve and conversation. However, the problem of poor stability and low rate capability for cobalt sulfides restrict its practical application. Thin carbon layer (TCL) coated has been regarded as a promising constructing strategy for high performance supercapacitors, because TCL can promote the tremendous properties of bare materials. In this literature, we report a very interesting phenomenon that different distribution of in-situ carbon coated hollow CoS2 nanocages (external and both external and interior) can be synthesized only by adjusting sulfuration time, followed by calcination. Moreover, it is clearly observed that CoS2-C@TCL exhibits significant improvement for specific capacitance and good stability (better than CoS2@TCL and CoS2). These results compel us to design a series of experiments to figure out the reason and the more detailed mechanism is discussed in paper. More importantly, it will provide a new strategy for synthesis of special structure with in-situ carbon coated sulfide for energy conversion.

  5. Assessment of carbon fiber-reinforced polyphenylene sulfide by means of laser ultrasound

    Science.gov (United States)

    Kalms, Michael; Peters, Christian; Wierbos, Ronald

    2011-04-01

    From automobile industry to aerospace, thermoformed composites are more and more in use. Thermoplastics offer a number of attractive applications in commercial use like short production times, tailored solutions, recyclability and lower cost. The thermoforming process allows for producing carbon fiber-reinforced parts in a wide range of different geometric shapes. On the other hand this benefit requires a demanding nondestructive testing procedure especially for security relevant parts. A contactless method which is able to fulfil this requirement is the extension of the ultrasound technique with laser technology. It opens up new opportunities for quality assessment during manufacturing like inspection of complex surfaces including small radii, remote observation and nondestructive testing of hot items directly after the thermal forming process. We describe the successful application of laser-based ultrasound on small complex thermoformed composite parts (Cetex® PPS). Cetex consists of semicrystalline polyphenylene sulfide thermoplastics providing outstanding toughness and excellent chemical and solvent resistance. It is qualified in aircraft industry for multiple structural applications. For instance, Cetex is used in the Airbus A380 engine air intakes and the wing fixed leading edge (J-Nose). We investigated several test samples with intentionally introduced defects. The smallest flaw size detected was 2 mm in diameter for delaminations and 6 mm in diameter for porosity.

  6. The flux of carbonyl sulfide and carbon disulfide between the atmosphere and a spruce forest

    Directory of Open Access Journals (Sweden)

    X. Xu

    2002-01-01

    Full Text Available Turbulent fluxes of carbonyl sulfide (COS and carbon disulfide (CS2 were measured over a spruce forest in Central Germany using the relaxed eddy accumulation (REA technique. A REA sampler was developed and validated using simultaneous measurements of CO2 fluxes by REA and by eddy correlation. REA measurements were conducted during six campaigns covering spring, summer, and fall between 1997 and 1999. Both uptake and emission of COS and CS2 by the forest were observed, with deposition occurring mainly during the sunlit period and emission mainly during the dark period. On the average, however, the forest acts as a sink for both gases. The average fluxes for COS and CS2 are  -93 ± 11.7 pmol m-2 s-1 and  -18 ± 7.6 pmol m-2 s-1, respectively. The fluxes of both gases appear to be correlated to photosynthetically active radiation and to the CO2 and chem{H_2O} fluxes, supporting the idea that the air-vegetation exchange of both gases is controlled by stomata. An uptake ratio COS/CO2 of 10 ± 1.7 pmol m mol-1 has been derived from the regression line for the correlation between the COS and CO2 fluxes. This uptake ratio, if representative for the global terrestrial net primary production, would correspond to a sink of 2.3 ± 0.5 Tg COS yr-1.

  7. Observations of the uptake of carbonyl sulfide (COS by trees under elevated atmospheric carbon dioxide concentrations

    Directory of Open Access Journals (Sweden)

    L. Sandoval-Soto

    2012-08-01

    Full Text Available Global change forces ecosystems to adapt to elevated atmospheric concentrations of carbon dioxide (CO2. We understand that carbonyl sulfide (COS, a trace gas which is involved in building up the stratospheric sulfate aerosol layer, is taken up by vegetation with the same triad of the enzymes which are metabolizing CO2, i.e. ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, phosphoenolpyruvate carboxylase (PEP-Co and carbonic anhydrase (CA. Therefore, we discuss a physiological/biochemical acclimation of these enzymes affecting the sink strength of vegetation for COS. We investigated the acclimation of two European tree species, Fagus sylvatica and Quercus ilex, grown inside chambers under elevated CO2, and determined the exchange characteristics and the content of CA after a 1–2 yr period of acclimation from 350 ppm to 800 ppm CO2. We demonstrate that a compensation point, by definition, does not exist. Instead, we propose to discuss a point of uptake affinity (PUA. The results indicate that such a PUA, the CA activity and the deposition velocities may change and may cause a decrease of the COS uptake by plant ecosystems, at least as long as the enzyme acclimation to CO2 is not surpassed by an increase of atmospheric COS. As a consequence, the atmospheric COS level may rise causing an increase of the radiative forcing in the troposphere. However, this increase is counterbalanced by the stronger input of this trace gas into the stratosphere causing a stronger energy reflection by the stratospheric sulfur aerosol into space (Brühl et al., 2012. These data are very preliminary but may trigger a discussion on COS uptake acclimation to foster measurements with modern analytical instruments.

  8. Continuous In-situ Measurements of Carbonyl Sulfide to Constrain Ecosystem Carbon and Water Exchange

    Science.gov (United States)

    Rastogi, B.; Kim, Y.; Berkelhammer, M. B.; Noone, D. C.; Lai, C. T.; Hollinger, D. Y.; Bible, K.; Leen, J. B.; Gupta, M.; Still, C. J.

    2014-12-01

    Understanding the processes that control the terrestrial exchange of carbon and water are critical for examining the role of forested ecosystems in changing climates. A small but increasing number of studies have identified Carbonyl Sulfide (OCS) as a potential tracer for photosynthesis. OCS is hydrolyzed by an irreversible reaction in leaf mesophyll cells that is catalyzed by the enzyme, carbonic anhydrase. Leaf-level field and greenhouse studies indicate that OCS uptake is controlled by stomatal activity and that the ratio of OCS and CO2 uptake is reasonably constant. Existing studies on ecosystem OCS exchange have been based on laboratory measurements or short field campaigns and therefore little information on OCS exchange in a natural ecosystem over longer timescales is available. The objective of this study is to further assess the stability of OCS as a tracer for canopy photosynthesis in an active forested ecosystem and also to assess its utility for constraining transpiration, since both fluxes are mediated by canopy stomatal conductance. An off-axis integrated cavity output spectroscopy analyzer (Los Gatos Research Inc.) was deployed at the Wind River Experimental Forest in Washington (45.8205°N, 121.9519°W). Canopy air was sampled from three heights to measure vertical gradients of OCS within the canopy, and OCS exchange between the forest and the atmosphere. Here we take advantage of simultaneous measurements of the stable isotopologues of H2O and CO2 at corresponding heights as well as NEE (Net Ecosystem Exchange) from eddy covariance measurements to compare GPP (Gross Primary Production) and transpiration estimates from a variety of independent techniques. Our findings seek to allow assessment of the environmental and ecophysicological controls on evapotranspiration rates, which are projected to change in coming decades, and are otherwise poorly constrained.

  9. Metal sulfide coated multiwalled carbon nanotubes synthesized by an in situ method and their optical limiting properties

    Science.gov (United States)

    Wu, Hui-Xia; Cao, Wei-Man; Chen, Qiang; Liu, Miao-Miao; Qian, Shi-Xiong; Jia, Neng-Qin; Yang, Hong; Yang, Shi-Ping

    2009-05-01

    A metal sulfide such as ZnS, CdS, Ag2S or PbS was coated on the sidewall of multiwalled carbon nanotubes (MWCNTs) by an in situ wet chemical synthesis approach via noncovalent functionalization of MWCNTs with a polyelectrolyte (polyethylenimine or poly(diallyldimethylammonium chloride)) without causing significant electronic and structural modification of the carbon nanotubes. Extensive characterizations of the fabricated nanocomposites have been performed using x-ray diffraction, transmission electron microscopy (TEM), high resolution TEM, energy dispersive x-ray spectroscopy, selected area electron diffraction, thermal gravimetric analysis, Fourier transform IR spectra, UV-vis spectra and x-ray photoelectron spectroscopy. The coating layers were composed of metal sulfide nanoparticles with a mean size of less than 10 nm. The optical limiting property measurements for some metal sulfide coated MWCNTs were carried out by the open-aperture z-scan technique. The results demonstrate that the samples suspended in water showed optical limiting behavior better than that of purified MWCNTs.

  10. Single Membrane Reactor Configuration for Separation of Hydrogen, Carbon Dioxide and Hydrogen Sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Micheal Roberts; Robert Zabransky; Shain Doong; Jerry Lin

    2008-05-31

    The objective of the project was to develop a novel complementary membrane reactor process that can consolidate two or more downstream unit operations of a coal gasification system into a single module for production of a pure stream of hydrogen and a pure stream of carbon dioxide. The overall goals were to achieve higher hydrogen production efficiencies, lower capital costs and a smaller overall footprint than what could be achieved by utilizing separate components for each required unit process/operation in conventional coal-to-hydrogen systems. Specifically, this project was to develop a novel membrane reactor process that combines hydrogen sulfide removal, hydrogen separation, carbon dioxide separation and water-gas shift reaction into a single membrane configuration. The carbon monoxide conversion of the water-gas-shift reaction from the coal-derived syngas stream is enhanced by the complementary use of two membranes within a single reactor to separate hydrogen and carbon dioxide. Consequently, hydrogen production efficiency is increased. The single membrane reactor configuration produces a pure H{sub 2} product and a pure CO{sub 2} permeate stream that is ready for sequestration. This project focused on developing a new class of CO{sub 2}-selective membranes for this new process concept. Several approaches to make CO{sub 2}-selective membranes for high-temperature applications have been tested. Membrane disks using the technique of powder pressing and high temperature sintering were successfully fabricated. The powders were either metal oxide or metal carbonate materials. Experiments on CO{sub 2} permeation testing were also performed in the temperature range of 790 to 940 C for the metal carbonate membrane disks. However, no CO{sub 2} permeation rate could be measured, probably due to very slow CO{sub 2} diffusion in the solid state carbonates. To improve the permeation of CO{sub 2}, one approach is to make membranes containing liquid or molten carbonates

  11. Hydrogen sulfide attenuates carbon tetrachloride-induced hepatotoxicity, liver cirrhosis and portal hypertension in rats.

    Directory of Open Access Journals (Sweden)

    Gang Tan

    Full Text Available BACKGROUND: Hydrogen sulfide (H(2S displays vasodilative, anti-oxidative, anti-inflammatory and cytoprotective activities. Impaired production of H(2S contributes to the increased intrahepatic resistance in cirrhotic livers. The study aimed to investigate the roles of H(2S in carbon tetrachloride (CCl(4-induced hepatotoxicity, cirrhosis and portal hypertension. METHODS AND FINDINGS: Sodium hydrosulfide (NaHS, a donor of H(2S, and DL-propargylglycine (PAG, an irreversible inhibitor of cystathionine γ-lyase (CSE, were applied to the rats to investigate the effects of H(2S on CCl(4-induced acute hepatotoxicity, cirrhosis and portal hypertension by measuring serum levels of H(2S, hepatic H(2S producing activity and CSE expression, liver function, activity of cytochrome P450 (CYP 2E1, oxidative and inflammatory parameters, liver fibrosis and portal pressure. CCl(4 significantly reduced serum levels of H(2S, hepatic H(2S production and CSE expression. NaHS attenuated CCl(4-induced acute hepatotoxicity by supplementing exogenous H(2S, which displayed anti-oxidative activities and inhibited the CYP2E1 activity. NaHS protected liver function, attenuated liver fibrosis, inhibited inflammation, and reduced the portal pressure, evidenced by the alterations of serum alanine aminotransferase (ALT, aspartate aminotransferase (AST, hyaluronic acid (HA, albumin, tumor necrosis factor (TNF-α, interleukin (IL-1β, IL-6 and soluble intercellular adhesion molecule (ICAM-1, liver histology, hepatic hydroxyproline content and α-smooth muscle actin (SMA expression. PAG showed opposing effects to NaHS on most of the above parameters. CONCLUSIONS: Exogenous H(2S attenuates CCl(4-induced hepatotoxicity, liver cirrhosis and portal hypertension by its multiple functions including anti-oxidation, anti-inflammation, cytoprotection and anti-fibrosis, indicating that targeting H(2S may present a promising approach, particularly for its prophylactic effects, against liver

  12. Carbonyl sulfide exchange in soils for better estimates of ecosystem carbon uptake

    Directory of Open Access Journals (Sweden)

    M. E. Whelan

    2015-08-01

    Full Text Available Carbonyl sulfide (COS measurements are one of the emerging tools to better quantify gross primary production (GPP, the largest flux in the global carbon cycle. COS is a gas with a similar structure to CO2; COS uptake is thought to be a proxy for GPP. However, soils are a potential source or sink of COS. This study presents a framework for understanding soil-COS interactions. Excluding wetlands, most of the few observations of isolated soils that have been made show small uptake of atmospheric COS. Recently, a series of studies at an agricultural site in the central United States found soil COS production under hot conditions an order of magnitude greater than fluxes at other sites. To investigate the extent of this phenomenon, soils were collected from 5 new sites and incubated in a variety of soil moisture and temperature states. We found that soils from a desert, an oak savannah, a deciduous forest, and a rainforest exhibited small COS fluxes, behavior resembling previous studies. However, soil from an agricultural site in Illinois, > 800 km away from the initial central US study site, demonstrated comparably large soil fluxes under similar conditions. These new data suggest that, for the most part, soil COS interaction is negligible compared to plant uptake of COS. We present a model that anticipates the large agricultural soil fluxes so that they may be taken into account. While COS air-monitoring data are consistent with the dominance of plant uptake, improved interpretation of these data should incorporate the soil flux parameterizations suggested here.

  13. Carbonyl sulfide exchange in soils for better estimates of ecosystem carbon uptake

    Science.gov (United States)

    Whelan, Mary E.; Hilton, Timothy W.; Berry, Joseph A.; Berkelhammer, Max; Desai, Ankur R.; Campbell, J. Elliott

    2016-03-01

    Carbonyl sulfide (COS) measurements are one of the emerging tools to better quantify gross primary production (GPP), the largest flux in the global carbon cycle. COS is a gas with a similar structure to CO2; COS uptake is thought to be a proxy for GPP. However, soils are a potential source or sink of COS. This study presents a framework for understanding soil-COS interactions. Excluding wetlands, most of the few observations of isolated soils that have been made show small uptake of atmospheric COS. Recently, a series of studies at an agricultural site in the central United States found soil COS production under hot conditions an order of magnitude greater than fluxes at other sites. To investigate the extent of this phenomenon, soils were collected from five new sites and incubated in a variety of soil moisture and temperature states. We found that soils from a desert, an oak savannah, a deciduous forest, and a rainforest exhibited small COS fluxes, behavior resembling previous studies. However, soil from an agricultural site in Illinois, > 800 km away from the initial central US study site, demonstrated comparably large soil fluxes under similar conditions. These new data suggest that, for the most part, soil COS interaction is negligible compared to plant uptake of COS. We present a model that anticipates the large agricultural soil fluxes so that they may be taken into account. While COS air-monitoring data are consistent with the dominance of plant uptake, improved interpretation of these data should incorporate the soil flux parameterizations suggested here.

  14. Developing sulfide-oxidizing biofilm on H2S-exhausted carbon for sustainable bio-regeneration and biofiltration.

    Science.gov (United States)

    Jiang, Xia; Yan, Rong; Tay, Joo Hwa

    2009-05-30

    The feasibility of developing biofilm on exhausted carbon using pre-deposited sulfur compounds as the sole energy source was studied, aiming to re-use them in odor biofiltration. The exhausted carbon with different properties, including surface pH, sulfur content and porosity, was used. A series of off-line trials were conducted to investigate the release of sulfur compounds from the exhausted carbon and the attachment of sulfide-oxidizing bacteria on the exhausted carbon. Without any pre-treatment, a few bacteria attachment on exhausted carbon was observed by SEM, due to possibly the limitation of reduced sulfur compounds release for bacterial growth. The biofilm development was much improved by adding NaOH solution to partially pre-desorb the deposited sulfur into liquid phase, which provided initial energy for bacterial growth. With the attached bacteria, the further significant release of the deposited sulfur was achieved through an additional driving force: biodegradation. The key issues for developing biofilm on exhausted carbon were concluded, which mainly concerned of desorption of pre-deposited reduced sulfur compounds and porosity of carbon. The sulfur-associated reactions occurring in developing biofilm on exhausted carbon was proposed. Bio-regeneration of exhausted carbon in the course of biofilm development was also preliminarily assessed.

  15. Carbonyl sulfide, dimethyl sulfide and carbon disulfide in the Pearl River Delta of southern China: Impact of anthropogenic and biogenic sources

    Science.gov (United States)

    Guo, H.; Simpson, I. J.; Ding, A. J.; Wang, T.; Saunders, S. M.; Wang, T. J.; Cheng, H. R.; Barletta, B.; Meinardi, S.; Blake, D. R.; Rowland, F. S.

    2010-10-01

    Reduced sulfur compounds (RSCs) such as carbonyl sulfide (OCS), dimethyl sulfide (DMS) and carbon disulfide (CS 2) impact radiative forcing, ozone depletion, and acid rain. Although Asia is a large source of these compounds, until now a long-term study of their emission patterns has not been carried out. Here we analyze 16 months of RSC data measured at a polluted rural/coastal site in the greater Pearl River Delta (PRD) of southern China. A total of 188 canister air samples were collected from August 2001 to December 2002. The OCS and CS 2 mixing ratios within these samples were higher in autumn/winter and lower in summer due to the influence of Asian monsoon circulations. Comparatively low DMS values observed in this coastal region suggest a relatively low biological productivity during summer months. The springtime OCS levels in the study region (574 ± 40 pptv) were 25% higher than those on other East Asia coasts such Japan, whereas the springtime CS 2 and DMS mixing ratios in the PRD (47 ± 38 pptv and 22 ± 5 pptv, respectively) were 3-30 times lower than elevated values that have been measured elsewhere in East Asia (Japan and Korea) at this time of year. Poor correlations were found among the three RSCs in the whole group of 188 samples, suggesting their complex and variable sources in the region. By means of backward Lagrangian particle release simulations, air samples originating from the inner PRD, urban Hong Kong and South China Sea were identified. The mean mixing ratio of OCS in the inner PRD was significantly higher than that in Hong Kong urban air and South China Sea marine air ( p 0.05). Using a linear regression method based on correlations with the urban tracer CO, the estimated OCS emission in inner PRD (49.6 ± 4.7 Gg yr -1) was much higher than that in Hong Kong (0.32 ± 0.05 Gg yr -1), whereas the estimated CS 2 and DMS emissions in the study region accounted for a very few percentage of the total CS 2 and DMS emission in China. These

  16. Vasoactivity of the gasotransmitters hydrogen sulfide and carbon monoxide in the chicken ductus arteriosus.

    Science.gov (United States)

    van der Sterren, Saskia; Kleikers, Pamela; Zimmermann, Luc J I; Villamor, Eduardo

    2011-10-01

    Besides nitric oxide (NO) and carbon monoxide (CO), hydrogen sulfide (H(2)S) is a third gaseous messenger that may play a role in controlling vascular tone and has been proposed to serve as an O(2) sensor. However, whether H(2)S is vasoactive in the ductus arteriosus (DA) has not yet been studied. We investigated, using wire myography, the mechanical responses induced by Na(2)S (1 μM-1 mM), which forms H(2)S and HS(-) in solution, and by authentic CO (0.1 μM-0.1 mM) in DA rings from 19-day chicken embryos. Na(2)S elicited a 100% relaxation (pD(2) 4.02) of 21% O(2)-contracted and a 50.3% relaxation of 62.5 mM KCl-contracted DA rings. Na(2)S-induced relaxation was not affected by presence of the NO synthase inhibitor l-NAME, the soluble guanylate cyclase (sGC) inhibitor ODQ, or the K(+) channel inhibitors tetraethylammonium (TEA; nonselective), 4-aminopyridine (4-AP, K(V)), glibenclamide (K(ATP)), iberiotoxin (BK(Ca)), TRAM-34 (IK(Ca)), and apamin (SK(Ca)). CO also relaxed O(2)-contracted (60.8% relaxation) and KCl-contracted (18.6% relaxation) DA rings. CO-induced relaxation was impaired by ODQ, TEA, and 4-AP (but not by L-NAME, glibenclamide, iberiotoxin, TRAM-34 or apamin), suggesting the involvement of sGC and K(V) channel stimulation. The presence of inhibitors of H(2)S or CO synthesis as well as the H(2)S precursor L-cysteine or the CO precursor hemin did not significantly affect the response of the DA to changes in O(2) tension. Endothelium-dependent and -independent relaxations were also unaffected. In conclusion, our results indicate that the gasotransmitters H(2)S and CO are vasoactive in the chicken DA but they do not suggest an important role for endogenous H(2)S or CO in the control of chicken ductal reactivity.

  17. Study of benzotriazole as corrosion inhibitors of carbon steel in chloride solution containing hydrogen sulfide using electrochemical impedance spectroscopy (EIS)

    Energy Technology Data Exchange (ETDEWEB)

    Solehudin, Agus, E-mail: asolehudin@upi.edu [Department of Mechanical Engineering Education, Indonesia University of Education (UPI), Bandung, West Java (Indonesia); Nurdin, Isdiriayani [Department of Chemical Engineering, Bandung Institute of Technology, Bandung, West Java (Indonesia)

    2014-03-24

    Corrosion and inhibition studies on API 5LX65 carbon steel in chloride solution containing various concentrations of benzotriazole has been conducted at temperature of 70°C using Electrochemical Impedance Spectroscopy (EIS). Corroded carbon steel surface with and without inhibitor have been observed using X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Energy Dispersive Spectroscopy (EDS). The objectives of this research are to study the performance of benzotriazole as corrosion inhibitors. The experimental results of carbon steel corrosion in 3.5% NaCl solution containing 500 mg/l H{sub 2}S at different BTAH concentrations showed that corrosion rate of carbon steel decreases with increasing of BTAH concentrations from 0 to 10 mmol/l. The inhibition efficiency of BTAH was found to be affected by its concentration. The optimum efficiency obtained of BTAH is 93% at concentration of 5 mmol/l. The result of XRD and EDS analysis reveal the iron sulfide (FeS) formation on corroded carbon steel surface without inhibitor. The EDS spectrum show the Nitrogen (N) bond on carbon steel surface inhibited by BTAH.

  18. Study of benzotriazole as corrosion inhibitors of carbon steel in chloride solution containing hydrogen sulfide using electrochemical impedance spectroscopy (EIS)

    Science.gov (United States)

    Solehudin, Agus; Nurdin, Isdiriayani

    2014-03-01

    Corrosion and inhibition studies on API 5LX65 carbon steel in chloride solution containing various concentrations of benzotriazole has been conducted at temperature of 70°C using Electrochemical Impedance Spectroscopy (EIS). Corroded carbon steel surface with and without inhibitor have been observed using X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Energy Dispersive Spectroscopy (EDS). The objectives of this research are to study the performance of benzotriazole as corrosion inhibitors. The experimental results of carbon steel corrosion in 3.5% NaCl solution containing 500 mg/l H2S at different BTAH concentrations showed that corrosion rate of carbon steel decreases with increasing of BTAH concentrations from 0 to 10 mmol/l. The inhibition efficiency of BTAH was found to be affected by its concentration. The optimum efficiency obtained of BTAH is 93% at concentration of 5 mmol/l. The result of XRD and EDS analysis reveal the iron sulfide (FeS) formation on corroded carbon steel surface without inhibitor. The EDS spectrum show the Nitrogen (N) bond on carbon steel surface inhibited by BTAH.

  19. Carbon, nitrogen, oxygen and sulfide budgets in the Black Sea : a biogeochemical model of the whole water column coupling the oxic and anoxic parts

    NARCIS (Netherlands)

    Grégoire, M.; Soetaert, K.E.R.

    2010-01-01

    Carbon, nitrogen, oxygen and sulfide budgets are derived for the Black Sea water column from a coupled physical–biogeochemical model. The model is applied in the deep part of the sea and simulates processes over the whole water column including the anoxic layer that extends from similar, equals115 m

  20. XAFS study on the sulfidation mechanisms of Co-Mo catalysts supported on activated carbon and alumina: effect of complexing agent.

    Science.gov (United States)

    Tsuji, K; Umeki, T; Yokoyama, Y; Kitada, T; Iwanami, Y; Nonaka, O; Shimada, H; Matsubayashi, N; Nishijima, A; Nomura, M

    2001-03-01

    The effect of nitrilotriacetic acid (NTA) as a complexing agent on the sulfidation mechanisms of Co-Mo catalysts supported on activated carbon and alumina was examined by the XAFS technique. The XAFS results revealed that NTA interacted with Co atoms and formed the Co-NTA interaction, while it showed almost no influence on the local structures around Mo atoms. The Co-NTA interaction suppressed the aggregation of cobalt atoms and the interaction between cobalt and alumina during sulfiding, and consequently promoted the formation of the Co-Mo-S phase.

  1. Geochemical and mineralogical characterization of a neutral, low-sulfide/high-carbonate tailings impoundment, Markušovce, eastern Slovakia.

    Science.gov (United States)

    Hiller, Edgar; Petrák, Marián; Tóth, Roman; Lalinská-Voleková, Bronislava; Jurkovič, L'ubomír; Kučerová, Gabriela; Radková, Anežka; Sottník, Peter; Vozár, Jaroslav

    2013-11-01

    mineral assemblage and their occurrence follows the order: chalcopyrite > pyrite > tetrahedrite>arsenopyrite. The mineralogical composition of the tailings corresponds well to the primary mineralization mined. The neutralization capacity of the tailings is high, as confirmed by the values of neutralization potential to acid generation potential ratio, ranging from 6.7 to 63.9, and neutral to slightly alkaline pH of the tailings (paste pH 7.16-8.12) and the waters (pH 7.00-8.52). This is explained by abundant occurrence of carbonate minerals in the tailings, which readily neutralize the acidity generated by sulfide oxidation. The total solid-phase concentrations of metal(loid)s decrease as Cu>Sb>Hg>As and reflect the proportions of sulfides present in the tailings. Sulfide oxidation generally extends to a depth of 2 m. μ-XRD and EMPA were used to study secondary products developed on the surface of sulfide minerals and within the tailings. The main secondary minerals identified are goethite and X-ray amorphous Fe oxyhydroxides and their occurrence decreases with increasing tailings depth. Secondary Fe phases are found as mineral coatings or individual grains and retain relatively high amounts of metal(loid)s (up to 57.6 wt% Cu, 1.60 wt% Hg, 23.8 wt% As, and 2.37 wt% Sb). Based on batch leaching tests and lysimeter results, the mobility of potentially toxic elements in the tailings is low. The limited mobility of metals and metalloids is due to their retention by Fe oxyhydroxides and low solubilities of metal(loid)-bearing sulfides. The observations are consistent with PHREEQC calculations, which predict the precipitation of Fe oxyhydroxides as the main solubility-controlling mineral phases for As, Cu, Hg, and Sb. Waters discharging from tailings impoundment are characterized by a neutral to slightly alkaline pH (7.52-7.96) and low concentrations of dissolved metal(loid)s (<5-7.0 μg/L Cu, <0.1-0.3 μg/L Hg, 5.0-16 μg/L As, and 5.0-43 μg/L Sb). Primary factors

  2. Formation of "Chemically Pure" Magnetite from Mg-Fe-Carbonates Implications for the Exclusively Inorganic Origin of Magnetite and Sulfides in Martian Meteorite ALH84001

    Science.gov (United States)

    Golden, D. C.; Ming, Douglas W.; Lauer, H. V., Jr.; Morris, R. V.; Trieman, A. H.; McKay, G. A.

    2006-01-01

    Magnetite and sulfides in the black rims of carbonate globules in Martian meteorite ALH84001 have been studied extensively because of the claim by McKay et al. that they are biogenic in origin. However, exclusively inorganic (abiotic) processes are able to account for the occurrence of carbonate-sulfide-magnetite assemblages in the meteorite. We have previously precipitated chemically zoned and sulfide-bearing carbonate globules analogous to those in ALH84001 (at less than or equal to 150 C) from multiple fluxes of variable-composition Ca-Mg-Fe-CO2-S-H2O solutions. Brief heating of precipitated globules to approx. 470 C produced magnetite and pyrrhotite within the globules by thermal decomposition of siderite and pyrite, respectively. We have also shown that morphology of magnetite formed by inorganic thermal decomposition of Fe-rich carbonate is similar to the morphology of so-called biogenic magnetite in the carbonate globules of ALH84001. Magnetite crystals in the rims of carbonate globules in ALH84001 are chemically pure [Note: "Chemically pure" is defined here as magnetite with Mg at levels comparable or lower than Mg detected by [8] in ALH84001 magnetite]. A debate continues on whether or not chemically pure magnetite can form by the thermal decomposition of mixed Mg-Fe-carbonates that have formed under abiotic conditions. Thomas-Keprta et al. argue that it is not possible to form Mg-free magnetite from Mg-Fe-carbonate based on thermodynamic data. We previously suggested that chemically pure magnetite could form by the thermal decomposition of relatively pure siderite in the outer rims of the globules. Mg-Fe-carbonates may also thermally decompose under conditions conducive for formation of chemically pure magnetite. In this paper we show through laboratory experiments that chemically pure magnetite can form by an inorganic process from mixed Mg-Fe-carbonates.

  3. Influence of increasing dissolved inorganic carbon concentrations and decreasing pH on chemolithoautrophic bacteria from oxic-sulfidic interfaces

    Directory of Open Access Journals (Sweden)

    K. Mammitzsch

    2012-12-01

    Full Text Available Increases in the dissolved inorganic carbon (DIC concentration are expected to cause a decrease in the pH of ocean waters, a process known as ocean acidification. In oxygen-deficient zones this will add to already increased DIC and decreased pH values. It is not known how this might affect microbial communities and microbially mediated processes. In this study, the potential effects of ocean acidification on chemolithoautotrophic prokaryotes of marine oxic-anoxic transition zones were investigated, using the chemoautotrophic denitrifying ε-proteobacterium "Sulfurimonas gotlandica" strain GD1 as a model organism. This and related taxa use reduced sulfur compounds, e.g. sulfide and thiosulfate, as electron donors and were previously shown to be responsible for nitrate removal and sulfide detoxification in redox zones of the Baltic Sea water column but occur also in other oxygen-deficient marine systems. Bacterial cell growth within a broad range of DIC concentrations and pH values was monitored and substrate utilization was determined. The results showed that the DIC saturation concentration for growth was already reached at 800 μM, which is well below in situ DIC levels. The pH optimum was between 6.6 and 8.0. Within a pH range of 6.6–7.1 there was no significant difference in substrate utilization; however, at lower pH values cell growth decreased sharply and cell-specific substrate consumption increased. These findings suggest that a direct effect of ocean acidification, with the predicted changes in pH and DIC, on chemolithoautotrophic bacteria such as "S. gotlandica" str. GD1 is generally not very probable.

  4. Template-free formation of carbon nanotube-supported cobalt sulfide@carbon hollow nanoparticles for stable and fast sodium ion storage

    Science.gov (United States)

    Han, Fei; Jun Tan, Clara Yi; Gao, Zhiqiang

    2017-01-01

    Carbon-coated cobalt sulfide (CoS) hollow nanoparticles on carbon nanotube (CNT) networks are synthesized by combining three simple approaches: direct growth of Co3O4 nanocrystals on the CNT backbones, chemical conversion of the Co3O4 nanocrystals to CoS hollow nanoparticles, and the spatial introduction of conformal surface modification by carbon. It is noteworthy that the CoS hollow nanoparticles with inner cavity of <50 nm and an average wall thickness of 6-8 nm are derived from a template-free method. Such a template-free-derived multifunctional nanostructure design achieves the amalgamation of the favorite traits of one-dimensional conducting networks, hollow nanoparticles, and surface modification, thus resulting in much enhanced charge transfer, ion transport, and upholding the integrity of the electrode and electrode/electrolyte interface. When applied the synthesized CoS-based material as anodes in sodium-ion batteries (SIBs), excellent performance is observed. For instance, a reversible specific capacity of 562 mAh g-1 at 100 mA g-1 and a capacity retention rate of 90% after 200 cycles at a higher current density of 500 mA g-1 are obtained. Moreover, a superior rate capability is observed with reversible specific capacities of 341 and 276 mAh g-1 at 2000 and at 5000 mA g-1, respectively.

  5. Facile fabrication of novel porous graphitic carbon nitride/copper sulfide nanocomposites with enhanced visible light driven photocatalytic performance.

    Science.gov (United States)

    Chen, Xi; Li, Huankun; Wu, Yuxin; Wu, Hanshuo; Wu, Laidi; Tan, Pengfei; Pan, Jun; Xiong, Xiang

    2016-08-15

    In this work, a novel organic-inorganic heterostructured photocatalyst: porous graphitic carbon nitride (g-C3N4) hybrid with copper sulfide (CuS) had been synthesized via a precipitation-deposition method at low temperature for the first time. UV-vis spectroscopy revealed the porous g-C3N4/CuS nanocomposites showed a strong and broad visible light absorption. Furthermore, the g-C3N4/CuS nanocomposites showed higher photocatalytic activity in the photodegradation of various organic dyes than that of pure g-C3N4 and CuS, and the selected sample of g-C3N4/CuS-2 exhibited the best photocatalytic activity under visible light. The good photocatalytic activity could be ascribed to the matching of the g-C3N4 and CuS band gap energies. Besides, photoluminescent spectra and photoelectrochemical measurements also proved that the CuS/g-C3N4 could greatly enhance the charge generation and suppress the charge recombination of photogenerated carriers. According to the experimental result, a possible photocatalytic mechanism has been proposed. Due to the high stability, the porous g-C3N4/CuS could be applied in the field of environmental remediation. Our work highlights that coupling semiconductors with well-matched band energies provides a facile way to improve the photocatalytic activity.

  6. Diurnal odor, ammonia, hydrogen sulfide, and carbon dioxide emission profiles of confined swine grower/finisher rooms.

    Science.gov (United States)

    Sun, Gang; Guo, Huiqing; Peterson, Jonathan; Predicala, Bernardo; Laguë, Claude

    2008-11-01

    The objective of this study was to obtain diurnal variation profiles of odor and gas (ammonia [NH3], hydrogen sulfide [H2S], carbon dioxide [CO2]) concentrations and emission rate (OGCER) from confined swine grower/ finisher rooms under three typical weather conditions (warm, mild, and cold weather) in a year. Two grower/ finisher rooms, one with a fully slatted floor and the other with partially slatted floors, were measured for 2 consecutive days under each weather condition. The results revealed that the diurnal OGCER in the room with a fully slatted floor was 9.2-39.4% higher than that with a partially slatted floor; however, no significant differences in the diurnal OGCER were found between these two rooms, except for the NH3 concentrations in August, the NH3 and H2S concentrations and emissions in October, and odor concentrations and emissions in February (p > 0.05). The OGCER variations presented different diurnal patterns as affected by time of day, season, type of floor, ventilation rate, animal growth cycles, in-house manure storage, and weather conditions. Significant diurnal fluctuations in the OGCER (except for the odor concentrations and H2S emissions) were observed in August (p dispersion modeling to decrease the great incertitude of setback determination using randomly measured data.

  7. Seasonal odor, ammonia, hydrogen sulfide, and carbon dioxide concentrations and emissions from swine grower-finisher rooms.

    Science.gov (United States)

    Sun, Gang; Guo, Huiqing; Peterson, Jonathan

    2010-04-01

    Seasonal odor and gas (ammonia [NH3], hydrogen sulfide [H2S], and carbon dioxide [CO2]) concentrations and emission rates (OGCERs) from swine facilities are vital for providing accurate source emissions and reducing the uncertainty of setback distances on the basis of emission data. In this study, a repeated measurement experimental method and a split-block statistical model were used to obtain seasonal OGCER profiles from two types of swine grower-finisher rooms in Saskatchewan, Canada, over a 12-month period. The results indicate that the OGCERs were significantly affected by the sampling month and ambient temperature (P dispersion models to reduce uncertainties in setback calculations. It was also found that the seasonal OGCERs from the rooms with fully slatted floors were 6.3-40.6% higher than those with partially slatted floors. The seasonal OGCERs (except for the NH3 concentrations in October, November, and January; the CO2 concentrations in August; and the CO2 emission rates in December) between these two rooms for each measuring month did not differ significantly (P > 0.05). The measured gas concentrations were generally below the permissible exposure limits (PELs) established by the Occupational Safety and Health Administration (OSHA) throughout the year except for the NH3 concentrations in cold weather (December, January, and February).

  8. Development of carbon nanotube and graphite filled polyphenylene sulfide based bipolar plates for all-vanadium redox flow batteries

    Science.gov (United States)

    Caglar, Burak; Fischer, Peter; Kauranen, Pertti; Karttunen, Mikko; Elsner, Peter

    2014-06-01

    In this study, synthetic graphite and carbon nanotube (CNT) filled polyphenylene sulfide (PPS) based bipolar plates are produced by using co-rotating twin-screw extruder and injection molding. Graphite is the main conductive filler and CNTs are used as bridging filler between graphite particles. To improve the dispersion of the fillers and the flow behavior of the composite, titanate coupling agent (KR-TTS) is used. The concentration effect of CNTs and coupling agent on the properties of bipolar plates are examined. At 72.5 wt.% total conductive filler concentration, by addition of 2.5 wt.% CNT and 3 wt.% KR-TTS; through-plane and in-plane electrical conductivities increase from 1.42 S cm-1 to 20 S cm-1 and 6.4 S cm-1 to 57.3 S cm-1 respectively compared to sample without CNTs and additive. Extruder torque value and apparent viscosity of samples decrease significantly with coupling agent and as a result; the flow behavior is positively affected. Flexural strength is improved 15% by addition of 1.25 wt.% CNT. Differential scanning calorimeter (DSC) analysis shows nucleating effect of conductive fillers on PPS matrix. Corrosion measurements, cyclic voltammetry and galvanostatic charge-discharge tests are performed to examine the electrochemical stability and the performance of produced bipolar plates in all-vanadium redox flow battery.

  9. Degradation of carbonyl sulfide by Actinomycetes and detection of clade D of β-class carbonic anhydrase.

    Science.gov (United States)

    Ogawa, Takahiro; Kato, Hiromi; Higashide, Mitsuru; Nishimiya, Mami; Katayama, Yoko

    2016-09-25

    Carbonyl sulfide (COS) is an atmospheric trace gas and one of the sources of stratospheric aerosol contributing to climate change. Although one of the major sinks of COS is soil, the distribution of COS degradation ability among bacteria remains unclear. Seventeen out of 20 named bacteria belonging to Actinomycetales had COS degradation activity at mole fractions of 30 parts per million by volume (ppmv) COS. Dietzia maris NBRC 15801(T) and Mycobacterium sp. THI405 had the activity comparable to a chemolithoautotroph Thiobacillus thioparus THI115 that degrade COS by COS hydrolase for energy production. Among 12 bacteria manifesting rapid degradation at 30 ppmv COS, Dietzia maris NBRC 15801(T) and Streptomyces ambofaciens NBRC 12836(T) degraded ambient COS (∼500 parts per trillion by volume). Geodermatophilus obscurus NBRC 13315(T) and Amycolatopsis orientalis NBRC 12806(T) increased COS concentrations. Moreover, six of eight COS degrading bacteria isolated from soils had partial nucleotide sequences similar to that of the gene encoding clade D of β-class carbonic anhydrase, which included COS hydrolase. These results indicate the potential importance of Actinomycetes in the role of soils as sinks of atmospheric COS.

  10. High temperature hydrogen sulfide adsorption on activated carbon - I. Effects of gas composition and metal addition

    Science.gov (United States)

    Cal, M.P.; Strickler, B.W.; Lizzio, A.A.

    2000-01-01

    Various types of activated carbon sorbents were evaluated for their ability to remove H2S from a simulated coal gas stream at a temperature of 550 ??C. The ability of activated carbon to remove H2S at elevated temperature was examined as a function of carbon surface chemistry (oxidation, thermal desorption, and metal addition), and gas composition. A sorbent prepared by steam activation, HNO3 oxidation and impregnated with Zn, and tested in a gas stream containing 0.5% H2S, 50% CO2 and 49.5% N2, had the greatest H2S adsorption capacity. Addition of H2, CO, and H2O to the inlet gas stream reduced H2S breakthrough time and H2S adsorption capacity. A Zn impregnated activated carbon, when tested using a simulated coal gas containing 0.5% H2S, 49.5% N2, 13% H2, 8.5% H2O, 21% CO, and 7.5% CO2, had a breakthrough time of 75 min, which was less than 25 percent of the length of breakthrough for screening experiments performed with a simplified gas mixture of 0.5% H2S, 50% CO2, and 49.5% N2.

  11. Geochemistry of arsenic in low sulfide-high carbonate coal waste rock, Elk Valley, British Columbia, Canada.

    Science.gov (United States)

    Biswas, Ashis; Hendry, M Jim; Essilfie-Dughan, Joseph

    2017-02-01

    This study investigated the geochemistry of arsenic (As) in low sulfide-high carbonate coal waste rock of the Elk Valley, British Columbia, Canada. Its abundance and mineralogical associations in waste rock of different placement periods were determined in addition to its mobilization into porewater and rock-drain effluent. The mean (5.34mg/kg; 95% confidence interval: 4.95-5.73mg/kg) As concentration in the waste rock was typical of sedimentary rock. Electron microprobe and As K-edge X-ray absorption near-edge spectroscopic analyses showed the As is predominantly associated with primary pyrites in both source and freshly blasted waste rock. However, in aged waste rock the As is associated with both primary pyrites and secondary Fe oxyhydroxides. Oxidation of pyrite in waste rock dumps was reflected by the presence of high concentrations of SO4(2-) in porewater and oxidation rims of Fe oxyhydroxides around pyrite grains. Acid released from pyrite oxidation to Fe oxyhydroxides is neutralized by carbonate mineral dissolution that buffers the pH in the waste rock to circumneutral values. Adsorption of As onto secondary Fe oxyhydroxides provides an internal geochemical control on As release during pyrite oxidation and porewater flushing from the dump, resulting in the low As concentrations observed in porewater (median: 9.91μg/L) and rock-drain effluent (median: 0.31μg/L). Secondary Fe oxyhydroxides act as a long-term sink for As under present day hydrologic settings in waste rock dumps in the Elk Valley.

  12. Depositional environments inferred from variations of calcium carbonate, organic carbon, and sulfide sulfur: a core from southeastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Paropkari, A; Iyer, S.D.; Chauhan, O; PrakashBabu, C.

    The variations in CaCO3 and organic carbon and their inter-relationship in a core from the southeastern Arabian Sea (water depth 2,212 m) have been used to demarcate the Holocene/Pleistocene boundary; an increased terrigenous deposition during Late...

  13. Hollow-spherical composites of Polyaniline/Cobalt Sulfide/Carbon nanodots with enhanced magnetocapacitance and electromagnetic wave absorption capabilities

    Science.gov (United States)

    Ge, Chuanjun; Zhang, Xiang; Liu, Jian; Jin, Feng; Liu, Jichang; Bi, Hong

    2016-08-01

    Hollow-spherical composites of polyaniline/cobalt sulfide/carbon nanodots (PANI/CoS/CDs-0.5T) have been synthesized by in situ polymerization under an applied magnetic field (MF) of 0.5 T. As a control, PANI/CoS/CDs-0T composites have been synthesized without a MF. Both composites acting as electrodes present obvious magnetocapacitances at a scan rate of 100 mV s-1 while the electrochemical cell tested under an external MF of 0.5 T. Notably, PANI/CoS/CDs-0.5T composites show larger magnetocapacitances than PANI/CoS/CDs-0T composites at different scan rates from 5 to 100 mV s-1. Electrochemical impedance spectroscopy (EIS) results indicate that MF can reduce charge transfer resistance at electrode/electrolyte interface. More importantly, PANI/CoS/CDs-0.5T composites show a much stronger electromagnetic wave (EMW) absorbing capability than PANI/CoS/CDs-0T in the range of 2-18 GHz which is attributed to an increased dielectric loss and a magnetic loss in low frequency range of 2-12.5 GHz. MF-induced ferromagnetic nanodomains of Co2+ clusters in the PANI/CoS/CDs-0.5T composites increase the complex permittivity and create more interfacial polarizations or the Maxwell-Wagner effect, which leads to increased dielectric loss. Compared with PANI/CoS/CDs-0T composites with diamagnetic behaviour, MF-induced weak ferromagnetism of CoS in the PANI/CoS/CDs-0.5T composites has caused additional magnetic loss. This work provides an efficient way for modulating electrochemical or electromagnetic properties of inorganic/polymer nanocomposites by employing an external MF.

  14. "Smart poisoning" of Co/SiO2 catalysts by sulfidation for chirality-selective synthesis of (9,8) single-walled carbon nanotubes.

    Science.gov (United States)

    Yuan, Yang; Karahan, H Enis; Yıldırım, Cansu; Wei, Li; Birer, Özgür; Zhai, Shengli; Lau, Raymond; Chen, Yuan

    2016-10-14

    The chirality-selective synthesis of relatively large (diameter > 1 nm) single-walled carbon nanotubes (SWCNTs) is of great interest for a variety of practical applications, but only a few catalysts are available so far. Previous studies suggested that S (compounds) can enhance the chirality-selectivity of Co catalysts in SWCNT synthesis, however, the mechanism behind is not fully understood, and no tailorable methodology has yet been developed. Here, we demonstrate a facile approach to achieve the chirality-selective synthesis of SWCNTs by the sulfidation-based poisoning of silica-supported Co catalysts using a mixture of H2S and H2. The UV-vis-NIR, photoluminescence, and Raman spectroscopy results together show that the resulting SWCNTs have a narrow diameter distribution of around 1.2 nm, and (9,8) nanotubes have an abundance of ∼38% among the semiconducting species. More importantly, the carbon yield achieved by the sulfided catalyst (2.5 wt%) is similar to that of the nonsulfided one (2.7 wt%). The characterization of the catalysts by X-ray diffraction, X-ray photoelectron spectroscopy, X-ray fluorescence, and H2 temperature-programmed reduction shows that the sulfidation leads to the formation of Co9S8 nanoparticles. However, Co9S8 nanoparticles are reduced back to regenerate metallic Co nanoparticles during the synthesis of SWCNTs, which maintain a high carbon yield. In this process, Co9S8 nanoparticles seemingly intermediate the production of Co nanoparticles with narrow size distribution. Due to the fact that the poisoning step improves the quality of the end-product rather than hampering the growth process, we have coined the process developed as "smart poisoning". This study not only reveals the mechanism behind the beneficial role of S in the selective synthesis of relatively large SWCNTs but also presents a promising method to create chirality-selective catalysts with high activity for scalable synthesis.

  15. STUDY OF HYDROGEN SULFIDE REMOVAL FROM GROUNDWATER

    Directory of Open Access Journals (Sweden)

    T. Lupascu

    2013-06-01

    Full Text Available The process of the hydrogen sulfide removal from the underground water of the Hancesti town has been investigated. By oxygen bubbling through the water containing hydrogen sulfide, from the Hancesti well tube, sulfur is deposited in the porous structure of studied catalysts, which decreases their catalytic activity. Concomitantly, the process of adsorption / oxidation of hydrogen sulfide to sulfate take place. The kinetic research of the hydrogen sulfide removal from the Hancesti underground water, after its treatment by hydrogen peroxide, proves greater efficiency than in the case of modified carbonic adsorbents. As a result of used treatment, hydrogen sulfide is completely oxidized to sulfates

  16. The Role of Amines, Hydrogen Sulfide and Carbon Dioxide in the Formation of Prebiotic Macromolecules Surrounded by Membranes

    Science.gov (United States)

    Rajen, Gaurav

    2016-04-01

    Amphiphilic compounds are known to self-assemble into membranous structures when exposed to alternate dry and wet conditions. This paper presents a model of how such structures could form near hydrothermal vents while containing macromolecules such as amino acids. The formation of amino acids near deep ocean hydrothermal vents as precursors for the origins of life is problematic as amino acids degrade from thermal energy. In the model proposed here, amino acids would degrade into amines (near hydrothermal vents). Amines have an affinity to interact with carbon dioxide (CO2) and hydrogen sulfide (H2S), form weak heat-unstable salts, and then through exposure to thermal energy release the acid gases and regenerate back to amines. Amines carrying and releasing H2S and CO2 would help other macromolecules form along with amino acids within protected cell-like structures; the cyclical release and recapture of acid gases would subsequently help the amino acids form bonds; further thermal action would degrade some of the amines into polymers that provide more strength and rigidity to the membrane walls; and also enable escaping gases to form tubes within the surrounding membranes for inlet and outlet of chemicals. Consider that liquids and gases are undergoing thermal convection inside a porous medium, and the convecting liquids contain some amines. Consider now that an amine weak salt carrying H2S and another carrying CO2 is inside a vesicle that formed through self-assembly. As this vesicle moves around in the thermal convection cell it will come close to the heat source and release the H2S and CO2 inside the vesicle. As the vesicle moves away from the heat source, the gases would be reabsorbed into the amines. This process would create stability and a repeating set of reactions, reactants, and products forming and reforming - cyclical stability is a key criterion for more complex reactions to occur. Some of the amines present would reform into an amino acid (as occurs

  17. Development of highly sensitive electrochemical genosensor based on multiwalled carbon nanotubes-chitosan-bismuth and lead sulfide nanoparticles for the detection of pathogenic Aeromonas.

    Science.gov (United States)

    Fernandes, António Maximiano; Abdalhai, Mandour H; Ji, Jian; Xi, Bing-Wen; Xie, Jun; Sun, Jiadi; Noeline, Rasoamandrary; Lee, Byong H; Sun, Xiulan

    2015-01-15

    In this paper, we reported the construction of new high sensitive electrochemical genosensor based on multiwalled carbon nanotubes-chitosan-bismuth complex (MWCNT-Chi-Bi) and lead sulfide nanoparticles for the detection of pathogenic Aeromonas. Lead sulfide nanoparticles capped with 5'-(NH2) oligonucleotides thought amide bond was used as signalizing probe DNA (sz-DNA) and thiol-modified oligonucleotides sequence was used as fixing probe DNA (fDNA). The two probes hybridize with target Aeromonas DNA (tDNA) sequence (fDNA-tDNA-szDNA). The signal of hybridization is detected by differential pulse voltammetry (DPV) after electrodeposition of released lead nanoparticles (PbS) from sz-DNA on the surface of glass carbon electrode decorated with MWCNT-Chi-Bi, which improves the deposition and traducing electrical signal. The optimization of incubation time, hybridization temperature, deposition potential, deposition time and the specificity of the probes were investigated. Our results showed the highest sensibility to detect the target gene when compared with related biosensors and polymerase chain reaction (PCR). The detection limit for this biosensor was 1.0×10(-14) M. We could detect lower than 10(2) CFU mL(-1) of Aeromonas in spiked tap water. This method is rapid and sensitive for the detection of pathogenic bacteria and would become a potential application in biomedical diagnosis, food safety and environmental monitoring.

  18. Arrays of hierarchical nickel sulfides/MoS2 nanosheets supported on carbon nanotubes backbone as advanced anode materials for asymmetric supercapacitor

    Science.gov (United States)

    Yang, Xijia; Zhao, Lijun; Lian, Jianshe

    2017-03-01

    One-dimensional (1D) hierarchical structures composed of nickel sulfides/MoS2 (NMS) supported on carbon nanotube (CNT) are fabricated through a one-step facile glucose-assisted hydrothermal method (NMS/CNT). The curled and tangled 1D structure is intertwined with each other and constructs three-dimensional (3D) porous networks, providing easy access of electrolyte. Meanwhile, the formation of metallic 1T-2H hybridized MoS2 and the synergistic effect between the MoS2 layers and nickel sulfides (NS) nanoparticles promotes the ions diffusion on the surface of the electrode, and the void space formed between NMS sheets can endure volume change in redox process for more stable structures. Therefore, the assembled NMS/CNT//activated carbon (AC) asymmetric supercapacitor manifests favorable specific capacitance of 108 F g-1 at 0.5 A g-1, along with a high energy density of 40 Wh kg-1 and good cycling stability of almost 100% capacity maintained after 10,000 cycles, implying it's the promising candidate for energy storage.

  19. Pudding-typed cobalt sulfides/nitrogen and sulfur dual-doped hollow carbon spheres as a highly efficient and stable oxygen reduction electrocatalyst

    Science.gov (United States)

    Xiao, Junwu; Zhao, Chen; Hu, Chencheng; Xi, Jiangbo; Wang, Shuai

    2017-04-01

    Metal organic frameworks (MOFs) are rarely reported to be grown at the templates due to the strong inherent driving force for crystallization. Herein, we report a pathway to successfully synthesize Zeolitic imidazolate framework-67 (ZIF-67) grown at the unmodified SiO2 spheres from amorphous precursors, and further construct Pudding-typed electrocatalysts, where cobalt sulfides (CoSx) nanocrystals are embedded into nitrogen and sulfur dual-doped hollow carbon spheres (N, S-HCS). CoSx/N, S-HCS show good catalytic activity toward the oxygen reduction reaction (ORR), and the optimized performance is achieved with (CoSx/N, S-HCS)700 with the positive half-wave potentials of 0.90 V vs RHE, high selectivity, good long-term stability, and excellent tolerance against methanol-crossover effect in alkaline medium, which are even superior to that of the as-reported MOFs-derived catalysts and commercial Pt/C catalysts. The remarkable catalytic performance is originated from high reactivity of catalytic active sites composed of cobalt sulfides and nitrogen and sulfur dual-doped carbon matrices, and Pudding-typed hollow structure with proper graphitization degree to facilitate fast electron and ion transport and limit the dissolution and agglomeration of active sites during long-term operation.

  20. Nanostructured metal sulfides for energy storage.

    Science.gov (United States)

    Rui, Xianhong; Tan, Huiteng; Yan, Qingyu

    2014-09-07

    Advanced electrodes with a high energy density at high power are urgently needed for high-performance energy storage devices, including lithium-ion batteries (LIBs) and supercapacitors (SCs), to fulfil the requirements of future electrochemical power sources for applications such as in hybrid electric/plug-in-hybrid (HEV/PHEV) vehicles. Metal sulfides with unique physical and chemical properties, as well as high specific capacity/capacitance, which are typically multiple times higher than that of the carbon/graphite-based materials, are currently studied as promising electrode materials. However, the implementation of these sulfide electrodes in practical applications is hindered by their inferior rate performance and cycling stability. Nanostructures offering the advantages of high surface-to-volume ratios, favourable transport properties, and high freedom for the volume change upon ion insertion/extraction and other reactions, present an opportunity to build next-generation LIBs and SCs. Thus, the development of novel concepts in material research to achieve new nanostructures paves the way for improved electrochemical performance. Herein, we summarize recent advances in nanostructured metal sulfides, such as iron sulfides, copper sulfides, cobalt sulfides, nickel sulfides, manganese sulfides, molybdenum sulfides, tin sulfides, with zero-, one-, two-, and three-dimensional morphologies for LIB and SC applications. In addition, the recently emerged concept of incorporating conductive matrices, especially graphene, with metal sulfide nanomaterials will also be highlighted. Finally, some remarks are made on the challenges and perspectives for the future development of metal sulfide-based LIB and SC devices.

  1. Sources and sinks of carbonyl sulfide in a mountain grassland and relationships to the carbon dioxide exchange

    Science.gov (United States)

    Spielmann, Felix M.; Kitz, Florian; Hammerle, Albin; Gerdel, Katharina; Wohlfahrt, Georg

    2016-04-01

    The trace gas carbonyl sulfide (COS) has been proposed as a tracer for canopy gross primary production (GPP), canopy transpiration and stomatal conductance of plant canopies in the last few years. COS enters the plant leaf through the stomata and diffuses through the intercellular space, the cell wall, the plasma membrane and the cytosol like CO2. It is then catalyzed by the enzyme carbonic anhydrase (CA) in a one-way reaction to H2S and CO2. This one-way flux into the leaf makes COS a promising tracer for the GPP. However there is growing evidence, that plant leaves aren't the only contributors to the ecosystem flux of COS. Therefor the COS uptake of soil microorganisms also containing CA and abiotic COS production might have to be accounted for when using COS as a tracer at the ecosystem scale. The overarching objective of this study was to quantify the relationship between the ecosystem-scale exchange of COS, CO2 and H2O and thus to test for the potential of COS to be used as a tracer for the plant canopy CO2 and H2O exchange. More specifically we aimed at quantifying the contribution of the soil to the ecosystem-scale COS exchange in order to understand complications that may arise due to a non-negligible soil COS exchange. In May 2015 we set up our quantum cascade laser (QCL) (Aerodyne Research Inc., MA, USA) at a temperate mountain grassland in Stubai Valley close to the village of Neustift, Austria. Our site lies at the valley bottom and is an intensively managed mountain grassland, which is cut 3-4 times a year. With the QCL we were able to measure concurrently the concentrations of COS, CO2, H2O (and CO) at a frequency of 10 Hz with minimal noise. This allowed us to conduct ecosystem-scale eddy covariance measurements. The eddy covariance flux measurements revealed that the COS uptake continues at night, which we confirmed was not caused by soil microorganisms, as the soil exchange was close to neutral during nighttime. Instead, the nocturnal COS uptake

  2. Replacement of hazardous chromium impregnating agent from silver/copper/chromium-impregnated active carbon using triethylenediamine to remove hydrogen sulfide, trichloromethane, ammonia, and sulfur dioxide.

    Science.gov (United States)

    Wu, Li-Chun; Chung, Ying-Chien

    2009-03-01

    Activated carbon (AC) is widely used as an effective adsorbent in many applications, including industrial-scale air purification systems and air filter systems in gas masks. In general, ACs without chemical impregnation are good adsorbents of organic vapors but poor adsorbents of low-molecular-weight or polar gases such as chlorine, sulfur dioxide (SO2), formaldehyde, and ammonia (NH3). Impregnated ACs modified with metallic impregnating agents (ASC-carbons; e.g., copper, chromium, and silver) enhance the adsorbing properties of the ACs for simultaneously removing specific poisonous gases, but disposal of the chromium metal salt used to impregnate the ACs has the potential to result in situations that are toxic to both humans and the environment, thereby necessitating the search for replaceable organic impregnating agents that represent a much lower risk. The aim of this study was to assess the gas removal efficiency of an AC in which the organic impregnating agent triethylenediamine (TEDA) largely replaced the metallic impregnating agent chromium. We assessed batch and continuous adsorption capacities in situ for removing simulated hydrogen sulfide (H2S), trichloromethane (CHCl3), NH3, and SO2 gases. Brunauer-Emmet-Teller measurements and scanning electron microscopy analyses identified the removal mechanism by which TEDA-impregnated AS-carbon (dechromium ASC-carbon) adsorbs gases and determined the removal capacity for H2S, CHCl3, NH3, and SO2 to be 311, 258, 272, and 223 mg/g-C, respectively. These results demonstrate that TEDA-impregnated AS-carbon is significantly more efficient than ASC-carbon in adsorbing these four gases. Organic TEDA-impregnating agents have also been proven to be a reliable and environmental friendly agent and therefore a safe replacement of the hazardous chromium found in conventional ASC-carbon used in removing toxic gases from the airstream.

  3. 一氧化碳和硫化氢在颈动脉体缺氧反应中的调节作用%Hypoxia responses led by carotid body is regulated by carbon monoxide and hydrogen sulfide

    Institute of Scientific and Technical Information of China (English)

    黄跃宇; 夏建华; 石学银

    2008-01-01

    传统认为一氧化碳和硫化氢为有毒气体,但近年的研究表明在颈动脉体感受低氧的过程中,这两种气体起重要的调节作用.一氧化碳通过增加内向钾离子电流抑制窦神经;硫化氢供体硫氢化钠则呈剂量依赖性兴奋窦神经.并且一氧化碳供体能完全逆转硫化氢对窦神经的兴奋作用.因而,一氧化碳和硫化氢共同调节颈动脉体对低氧状态反应的信号转导.%Carbon monoxide and hydrogen sulfide, both of which are well known toxic agents, are now demonstrated as critical gaseous mediators in carotid body when it responds to hypoxia. While carbon monoxide reduces sinus nerve impulses by decreasing inward potassium ion flux, sodium hydrosulfide, a donor of hydrogen sulfide, exerts an opposite effect in a dose - dependent manner.However, the exciting effect of hydrogen sulfide will be reversed completely after the donor of carbon monoxide is subjected. In this way, carbon monoxide and hydrogen sulfide intermingle into the regulation to the hypoxic information transduetion.

  4. Hydrogen sulfide in signaling pathways.

    Science.gov (United States)

    Olas, Beata

    2015-01-15

    For a long time hydrogen sulfide (H₂S) was considered a toxic compound, but recently H₂S (at low concentrations) has been found to play an important function in physiological processes. Hydrogen sulfide, like other well-known compounds - nitric oxide (NO) and carbon monoxide (CO) is a gaseous intracellular signal transducer. It regulates the cell cycle, apoptosis and the oxidative stress. Moreover, its functions include neuromodulation, regulation of cardiovascular system and inflammation. In this review, I focus on the metabolism of hydrogen sulfide (including enzymatic pathways of H₂S synthesis from l- and d-cysteine) and its signaling pathways in the cardiovascular system and the nervous system. I also describe how hydrogen sulfide may be used as therapeutic agent, i.e. in the cardiovascular diseases.

  5. Emissions of ammonia, carbon dioxide, and hydrogen sulfide from swine wastewater during and after acidification treatment: effect of pH, mixing and aeration

    DEFF Research Database (Denmark)

    Dai, Xiao-Rong; Blanes-Vidal, Victoria

    2013-01-01

    This study aimed at evaluating the effect of swine slurry acidification and acidification-aeration treatments on ammonia (NH(3)), carbon dioxide (CO(2)) and hydrogen sulfide (H(2)S) emissions during slurry treatment and subsequent undisturbed storage. The study was conducted in an experimental...... setup consisting of nine dynamic flux chambers. Three pH levels (pH = 6.0, pH = 5.8 and pH = 5.5), combined with short-term aeration and venting (with an inert gas) treatments were studied. Acidification reduced average NH(3) emissions from swine slurry stored after acidification treatment compared...... on average NH(3), CO(2) and H(2)S emissions both during the process and from stored slurry after venting treatments. During aeration treatment, the NH(3), CO(2) and H(2)S release pattern observed was related to the liquid turbulence caused by the gas bubbles rather than to biological oxidation processes...

  6. A coupled model of the global cycles of carbonyl sulfide and CO2: A possible new window on the carbon cycle

    Science.gov (United States)

    Berry, Joe; Wolf, Adam; Campbell, J. Elliott; Baker, Ian; Blake, Nicola; Blake, Don; Denning, A. Scott; Kawa, S. Randy; Montzka, Stephen A.; Seibt, Ulrike; Stimler, Keren; Yakir, Dan; Zhu, Zhengxin

    2013-06-01

    Carbonyl sulfide (COS) is an atmospheric trace gas that participates in some key reactions of the carbon cycle and thus holds great promise for studies of carbon cycle processes. Global monitoring networks and atmospheric sampling programs provide concurrent data on COS and CO2 concentrations in the free troposphere and atmospheric boundary layer over vegetated areas. Here we present a modeling framework for interpreting these data and illustrate what COS measurements might tell us about carbon cycle processes. We implemented mechanistic and empirical descriptions of leaf and soil COS uptake into a global carbon cycle model (SiB 3) to obtain new estimates of the COS land flux. We then introduced these revised boundary conditions to an atmospheric transport model (Parameterized Chemical Transport Model) to simulate the variations in the concentration of COS and CO2 in the global atmosphere. To balance the threefold increase in the global vegetation sink relative to the previous baseline estimate, we propose a new ocean COS source. Using a simple inversion approach, we optimized the latitudinal distribution of this ocean source and found that it is concentrated in the tropics. The new model is capable of reproducing the seasonal variation in atmospheric concentration at most background atmospheric sites. The model also reproduces the observed large vertical gradients in COS between the boundary layer and free troposphere. Using a simulation experiment, we demonstrate that comparing drawdown of CO2 with COS could provide additional constraints on differential responses of photosynthesis and respiration to environmental forcing. The separation of these two distinct processes is essential to understand the carbon cycle components for improved prediction of future responses of the terrestrial biosphere to changing environmental conditions.

  7. NEAR-CONTINUOUS MEASUREMENT OF HYDROGEN SULFIDE AND CARBONYL SULFIDE BY AN AUTOMATIC GAS CHROMATOGRAPH

    Science.gov (United States)

    An automatic gas chromatograph with a flame photometric detector that samples and analyzes hydrogen sulfide and carbonyl sulfide at 30-s intervals is described. Temperature programming was used to elute trace amounts of carbon disulfide present in each injection from a Supelpak-S...

  8. Adsorption/desorption of low concentration of carbonyl sulfide by impregnated activated carbon under micro-oxygen conditions.

    Science.gov (United States)

    Wang, Xueqian; Qiu, Juan; Ning, Ping; Ren, Xiaoguang; Li, Ziyan; Yin, Zaifei; Chen, Wei; Liu, Wei

    2012-08-30

    Activated carbon modified with different impregnants has been studied for COS removal efficiency under micro-oxygen conditions. Activated carbon modified with Cu(NO(3))(2)-CoPcS-KOH (denoted as Cu-Co-KW) is found to have markedly enhanced adsorption purification ability. In the adsorption purification process, the reaction temperature, oxygen concentration, and relative humidity of the gas are determined to be three crucial factors. A breakthrough of 43.34 mg COS/g adsorbent at 60°С and 30% relative humidity with 1.0% oxygen is shown in Cu-Co-KW for removing COS. The structures of the activated carbon samples are characterized using nitrogen adsorption, and their surface chemical structures are analyzed with X-ray photoelectron spectroscopy (XPS). Modification of Cu(NO(3))(2)-CoPcS-KOH appears to improve the COS removal capacity significantly, during which, SO(4)(2-) is presumably formed, strongly adsorbed, and present in the micropores ranging from 0.7 to 1.5 nm. TPD is used to identify the products containing sulfur species on the carbon surface, where SO(2) and COS are detected in the effluent gas generated from exhausted Cu-Co-KW (denoted Cu-Co-KWE). According to the current study results, the activated carbon impregnated with Cu(NO(3))(2)-CoPcS-KOH promises a good candidate for COS adsorbent, with the purified gas meeting requirements for desirable chemical feed stocks.

  9. Low-crystallinity molybdenum sulfide nanosheets assembled on carbon nanotubes for long-life lithium storage: Unusual electrochemical behaviors and ascending capacities

    Science.gov (United States)

    Li, Xiaodan; Wu, Gaoxiang; Chen, Jiewei; Li, Meicheng; Li, Wei; Wang, Tianyue; Jiang, Bing; He, Yue; Mai, Liqiang

    2017-01-01

    Low-crystallinity molybdenum sulfide (LCMS, Mo:S = 1:2.75) nanosheets synthesized by a facile and low temperature solvothermal method is now reported. The as-prepared LCMS anode material is composited of MoS2 layers mixed with amorphous MoS3, which leads to an unusual electrochemical process for lithium storage compared to typical MoS2 anode. The existence of MoS3 and Mo (VI) provide strong adsorption and binding sites for polar polysulphides, which compels abundant sulfur to turn into new-formed MoS3 rather than diffuse into electrolyte. To fully utilize this novel electrochemical process, LCMS is decorated on carbon nanotubes, obtaining well-dispersed CNTs@LCMS. As electrode material for lithium storage, CNTs@LCMS exhibits a noticable ascending trend in capacity from 820 mA h g-1 to 1350 mA h g-1 at 100 mA g-1 during 130 cycles. The persistent ascending capacity is ascribed to the increasing lithium storage caused by new-formed MoS3, combined with the reduced volume change benifiting from well-dispersed CNTs@LCMS. Furthermore, the ascending performance is proved to be able to effectively extend the circulation life (up to 200%) for lithium-ion batteries by mathematical modeling and calculation. Accordingly, the CNTs@LCMS composite is a promising anode material for long-life lithium-ion batteries.

  10. Emissions of ammonia, carbon dioxide, and hydrogen sulfide from swine wastewater during and after acidification treatment: effect of pH, mixing and aeration.

    Science.gov (United States)

    Dai, X R; Blanes-Vidal, V

    2013-01-30

    This study aimed at evaluating the effect of swine slurry acidification and acidification-aeration treatments on ammonia (NH(3)), carbon dioxide (CO(2)) and hydrogen sulfide (H(2)S) emissions during slurry treatment and subsequent undisturbed storage. The study was conducted in an experimental setup consisting of nine dynamic flux chambers. Three pH levels (pH = 6.0, pH = 5.8 and pH = 5.5), combined with short-term aeration and venting (with an inert gas) treatments were studied. Acidification reduced average NH(3) emissions from swine slurry stored after acidification treatment compared to emissions during storage of non-acidified slurry. The reduction were 50%, 62% and 77% when pH was reduce to 6.0, 5.8 and 5.5, respectively. However, it had no significant effect on average CO(2) and H(2)S emissions during storage of slurry after acidification. Aeration of the slurry for 30 min had no effect on average NH(3), CO(2) and H(2)S emissions both during the process and from stored slurry after venting treatments. During aeration treatment, the NH(3), CO(2) and H(2)S release pattern observed was related to the liquid turbulence caused by the gas bubbles rather than to biological oxidation processes in this study.

  11. Experimental design based response surface methodology optimization of ultrasonic assisted adsorption of safaranin O by tin sulfide nanoparticle loaded on activated carbon

    Science.gov (United States)

    Roosta, M.; Ghaedi, M.; Daneshfar, A.; Sahraei, R.

    2014-03-01

    In this research, the adsorption rate of safranine O (SO) onto tin sulfide nanoparticle loaded on activated carbon (SnS-NPAC) was accelerated by the ultrasound. SnS-NP-AC was characterized by different techniques such as SEM, XRD and UV-Vis measurements. The present results confirm that the ultrasound assisted adsorption method has remarkable ability to improve the adsorption efficiency. The influence of parameters such as the sonication time, adsorbent dosage, pH and initial SO concentration was examined and evaluated by central composite design (CCD) combined with response surface methodology (RSM) and desirability function (DF). Conducting adsorption experiments at optimal conditions set as 4 min of sonication time, 0.024 g of adsorbent, pH 7 and 18 mg L-1 SO make admit to achieve high removal percentage (98%) and high adsorption capacity (50.25 mg g-1). A good agreement between experimental and predicted data in this study was observed. The experimental equilibrium data fitting to Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich models show that the Langmuir model is a good and suitable model for evaluation and the actual behavior of adsorption. Kinetic evaluation of experimental data showed that the adsorption processes followed well pseudo-second-order and intraparticle diffusion models.

  12. Experimental design based response surface methodology optimization of ultrasonic assisted adsorption of safaranin O by tin sulfide nanoparticle loaded on activated carbon.

    Science.gov (United States)

    Roosta, M; Ghaedi, M; Daneshfar, A; Sahraei, R

    2014-03-25

    In this research, the adsorption rate of safranine O (SO) onto tin sulfide nanoparticle loaded on activated carbon (SnS-NPAC) was accelerated by the ultrasound. SnS-NP-AC was characterized by different techniques such as SEM, XRD and UV-Vis measurements. The present results confirm that the ultrasound assisted adsorption method has remarkable ability to improve the adsorption efficiency. The influence of parameters such as the sonication time, adsorbent dosage, pH and initial SO concentration was examined and evaluated by central composite design (CCD) combined with response surface methodology (RSM) and desirability function (DF). Conducting adsorption experiments at optimal conditions set as 4 min of sonication time, 0.024 g of adsorbent, pH 7 and 18 mg L(-1) SO make admit to achieve high removal percentage (98%) and high adsorption capacity (50.25 mg g(-)(1)). A good agreement between experimental and predicted data in this study was observed. The experimental equilibrium data fitting to Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich models show that the Langmuir model is a good and suitable model for evaluation and the actual behavior of adsorption. Kinetic evaluation of experimental data showed that the adsorption processes followed well pseudo-second-order and intraparticle diffusion models.

  13. Evaluation of microwave irradiation for analysis of carbonyl sulfide, carbon disulfide, cyanogen, ethyl formate, methyl bromide, sulfuryl fluoride, propylene oxide, and phosphine in hay.

    Science.gov (United States)

    Ren, Yonglin; Mahon, Daphne

    2007-01-10

    Fumigant residues in hay were "extracted" by microwave irradiation. Hay, in gastight glass flasks, was placed in a domestic microwave oven, and fumigants were released into the headspace by microwave irradiation. Power settings for maximum release of fumigants were determined for carbonyl sulfide (COS), carbon disulfide (CS(2)), cyanogen (C(2)N(2)), ethyl formate (EF), methyl bromide (CH(3)Br), sulfuryl fluoride (SF), propylene oxide (PPO), and phosphine (PH(3)). Recoveries of fortified samples were >91% for COS, CS(2), CH(3)Br, SF, PPO, and PH(3) and >76% for C(2)N(2) and EF. Completeness of extraction was assessed from the amount of fumigant retained by the microwaved hay. This amount was determined from further microwave irradiation and was always small (<5% of the amount obtained from the initial procedure). Limits of quantification were <0.1 mg/kg for COS, CS(2), C(2)N(2), EF, and PH(3) and <0.5 mg/kg for CH(3)Br, SF, and PPO. These low limits were essentially due to the absence of interference from solvents and no necessity to inject large-volume gas samples. The microwave method is rapid and solvent-free. However, care is required in selecting the appropriate power setting. The safety implications of heating sealed flasks in microwave ovens should be noted.

  14. Nickel Sulfide/Graphene/Carbon Nanotube Composites as Electrode Material for the Supercapacitor Application in the Sea Flashing Signal System

    Institute of Scientific and Technical Information of China (English)

    Hailong Chen; Ji Li; Conglai Long; Tong Wei; Guoqing Ning; Jun Yan; Zhuangjun Fan

    2014-01-01

    This work presents NiS/graphene/carbon nanotube (NiS/GNS/CNT) composites as electrode material for the supercapacitor application in sea flashing signal systems. NiS nanosheets were closely anchored on the conductive GNS-CNT networks. As a result, the NiS/GNS/CNT electrode showed a high specific capacitance of 2 377 F·g-1 at 2 mV·s-1 and good cycling stability compared with the pure NiS (1 599 F·g-1 ). The enhanced electrochemical performances are attributed to the synergetic effect between the conductive carbon and the pseudo-capacitive NiS. The high performance supercapacitor may provide application in the sea flashing signal system.

  15. Study of caffeine as corrosion inhibitors of carbon steel in chloride solution containing hydrogen sulfide using electrochemical impedance spectroscopy (EIS)

    Science.gov (United States)

    Solehudin, Agus; Berman, Ega Taqwali; Nurdin, Isdiriayani

    2015-09-01

    The corrosion behaviour of steel surface in the absence and presence of caffeine in 3.5% NaCl solution containing dissolved H2S gas is studied using electrochemical impedance spectroscopy (EIS). The experimental results of carbon steel corrosion in 3.5% NaCl solution containing 500 mg/l H2S at different caffeine concentrations showed that corrosion rate of carbon steel decreases with increasing of caffeine concentrations from 0 to 0,1 mmol/l. Whereas, the corrosion rate increase with increasing of caffeine concentrations from 1 to 10 mmol/l. It is clear that no inhibition efficiency increases with increasing inhibitor concentration. The optimum value of inhibition efficiency was 90% at a caffeine concentration of 0.1 mmol/l. This suggests that caffeine's performance as a corrosion inhibitor is more effective at a concentration of 0.1 mmol/l.

  16. Hydrogen sulfide and translational medicine

    OpenAIRE

    Guo, Wei; Cheng, Ze-yu; Zhu, Yi-Zhun

    2013-01-01

    Hydrogen sulfide (H2S) along with carbon monoxide and nitric oxide is an important signaling molecule that has undergone large numbers of fundamental investigations. H2S is involved in various physiological activities associated with the regulation of homeostasis, vascular contractility, pro- and anti-inflammatory activities, as well as pro- and anti-apoptotic activities etc. However, the actions of H2S are influenced by its concentration, reaction time, and cell/disease types. Therefore, H2S...

  17. Morphology-Controllable Synthesis of Zn-Co-Mixed Sulfide Nanostructures on Carbon Fiber Paper Toward Efficient Rechargeable Zinc-Air Batteries and Water Electrolysis.

    Science.gov (United States)

    Wu, Xiaoyu; Han, Xiaopeng; Ma, Xiaoya; Zhang, Wei; Deng, Yida; Zhong, Cheng; Hu, Wenbin

    2017-04-12

    It remains an ongoing challenge to develop cheap, highly active, and stable electrocatalysts to promote the sluggish electrocatalytic oxygen evolution, oxygen reduction, and hydrogen evolution reactions for rechargeable metal-air batteries and water-splitting systems. In this work, we report the morphology-controllable synthesis of zinc cobalt mixed sulfide (Zn-Co-S) nanoarchitectures, including nanosheets, nanoplates, and nanoneedles, grown on conductive carbon fiber paper (CFP) and the micronanostructure dependent electrochemical efficacy for catalyzing hydrogen and oxygen in zinc-air batteries and water electrolysis. The formation of different Zn-Co-S morphologies was attributed to the synergistic effect of decomposed urea products and the corrosion of NH4F. Among synthesized Zn-Co-S nanostructures, the nanoneedle arrays supported on CFP exhibit superior trifunctional activity for oxygen reduction, oxygen evolution, and hydrogen evolution reactions than its nanosheet and nanoplate counterparts through half reaction testing. It also exhibited better catalytic durability than Pt/C and RuO2. Furthermore, the Zn-Co-S nanoneedle/CFP electrode enables rechargeable Zn-air batteries with low overpotential (0.85 V), high efficiency (58.1%), and long cycling lifetimes (200 cycles) at 10 mA cm(-2) as well as considerable performance for water splitting. The superior performance is contributed to the integrated nanoneedle/CFP nanostructure, which not only provides enhanced electrochemical active area, but also facilitates ion and gas transfer between the catalyst surface and electrolyte, thus maintaining an effective solid-liquid-gas interface necessary for electrocatalysis. These results indicate that the Zn-Co-S nanoneedle/CFP system is a low cost, highly active, and durable electrode for highly efficient rechargeable zinc-air batteries and water electrolysis in alkaline solution.

  18. Simultaneous ultrasound-assisted ternary adsorption of dyes onto copper-doped zinc sulfide nanoparticles loaded on activated carbon: Optimization by response surface methodology

    Science.gov (United States)

    Asfaram, Arash; Ghaedi, Mehrorang; Hajati, Shaaker; Goudarzi, Alireza; Bazrafshan, Ali Akbar

    2015-06-01

    The simultaneous and competitive ultrasound-assisted removal of Auramine-O (AO), Erythrosine (Er) and Methylene Blue (MB) from aqueous solutions were rapidly performed onto copper-doped zinc sulfide nanoparticles loaded on activated carbon (ZnS:Cu-NP-AC). ZnS:Cu nanoparticles were studied by FESEM, XRD and TEM. First, the effect of pH was optimized in a one-at-a-time procedure. Then the dependency of dyes removal percentage in their ternary solution on the level and magnitude of variables such as sonication time, initial dyes concentrations and adsorbent dosage was fully investigated and optimized by central composite design (CCD) under response surface methodology (RSM) as well as by regarding desirability function (DF) as a good and general criterion. The good agreement found between experimental and predicted values supports and confirms the suitability of the present model to predict adsorption state. The applied ultrasound strongly enhanced mass transfer process and subsequently performance. Hence, a small amount of the adsorbent (0.04 g) was capable to remove high percentage of dyes, i.e. 100%, 99.6% and 100% for MB, AO and Er, respectively, in very short time (2.5 min). The experimental equilibrium data fitting to Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models showed that the Langmuir model applies well for the evaluation and description of the actual behavior of adsorption. The small amount of proposed adsorbent (0.015 g) was applicable for successful removal of dyes (RE > 99.0%) in short time (2.5 min) with high adsorption capacity in single component system (123.5 mg g-1 for MB, 123 mg g-1 for AO and 84.5 mg g-1 for Er). Kinetics evaluation of experiments at various time intervals reveals that adsorption processes can be well predicated and fitted by pseudo-second-order and Elovich models.

  19. Synthesis of nickel sulfide nanoparticles loaded on activated carbon as a novel adsorbent for the competitive removal of Methylene blue and Safranin-O.

    Science.gov (United States)

    Ghaedi, M; Pakniat, M; Mahmoudi, Z; Hajati, S; Sahraei, R; Daneshfar, A

    2014-04-05

    Nickel sulfide nanoparticle-loaded activated carbon (NiS-NP-AC) were synthesized as a novel adsorbent for simultaneous and rapid adsorption of Methylene blue (MB) and Safranin-O (SO), as most together compounds in wastewater. NiS-NP-AC was characterized using different techniques such as UV-visible, Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and Brunauer-Emmett-Teller (BET). The surface area of the adsorbent was found to be very high (1018m(2)/g according BET). By using central composite design (CCD), the effects of variables such as pH, adsorbent dosage, MB concentration, SO concentration and contact time on binary dyes removal were examined and optimized values were found to be 8.1, 0.022g, 17.8mg/L, and 5mg/L and 5.46min, respectively. The very short time required for the dyes removal makes this novel adsorbent as a promising tool for wastewater treatment applications. Different models were applied to analyze experimental isotherm data. Modified-extended Langmuir model showed good fit to equilibrium data with maximum adsorption capacity at 0.022g of adsorbent. An empirical extension of competitive modified-extended Langmuir model was proposed to predict the simultaneous adsorption behavior of MB and SO. Kinetic models were applied to fit the experimental data at various adsorbent dosages and initial dyes concentrations. It was seen that pseudo-second-order equation is suitable to fit the experimental data. Individual removalof each dye was also studied.

  20. Effects of Tai Chi exercise on blood pressure and plasma levels of nitric oxide, carbon monoxide and hydrogen sulfide in real-world patients with essential hypertension.

    Science.gov (United States)

    Pan, Xiaogui; Zhang, Yi; Tao, Sai

    2015-01-01

    Objective was to investigate the effects of Tai Chi exercise on nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H2S) levels, and blood pressure (BP) in patients with essential hypertension (EH). EH patients were assigned to the Tai Chi exercise group (HTC, n = 24), and hypertension group (HP, n = 16) by patients' willingness. Healthy volunteers matched for age and gender were recruited as control (NP, n = 16). HTC group performed Tai Chi (60 min/d, 6 d/week) for 12 weeks. Measurements (blood glucose, cholesterol, NO, CO, H2S and BP) were obtained at week 0, 6, and 12. SBP, MAP, and low-density lipoprotein cholesterol levels decreased, and high-density lipoprotein cholesterol levels increased by week 12 in the HTC group (all p < 0.05 versus baseline). Plasma NO, CO, and H2S levels in the HTC group were increased after 12 weeks (all p < 0.05 versus baseline). SBP, DBP and MAP levels were significantly lower in the HTC than in the HP group (all p < 0.05). However, no changes were observed in the HP and NP groups. Correlations were observed between changes in SBP and changes in NO, CO and H2S (r = -0.45, -0.51 and -0.46, respectively, all p < 0.05), and between changes in MAP and changes in NO, CO and H2S (r = -0.36, -0.45 and -0.42, respectively, all p < 0.05). In conclusion, Tai Chi exercise seems to have beneficial effects on BP and gaseous signaling molecules in EH patients. However, further investigation is required to understand the exact mechanisms underlying these observations, and to confirm these results in a larger cohort.

  1. In-situ growth of antimony sulfide in carbon nanoparticle matrix: Enhanced electrocatalytic activity as counter electrode in dye-sensitized solar cells

    Science.gov (United States)

    Sun, Panpan; Zhang, Ming; Ai, Changzhi; Wu, Zhixin; Lu, Shuang; Zhang, Xintong; Huang, Niu; Sun, Yihua; Sun, Xiaohua

    2016-07-01

    Considering the undesirable electrocatalytic activity toward I-/I3- redox system of prinstine antimony sulfide (Sb2S3) fabricated with the existing conditions, a mesoporous carbon nanoparticle film (CNP) is introduced here for in-situ growth of Sb2S3 to construct a Sb2S3@CNP hybrid catalyst. Based on a Sb-thiourea precursor solution, in-situ growth of Sb2S3 can be achieved via solution deposition (denoted as Sb2S3@CNP-S) as well as atmospheric pressure thermal evaporation (denoted as Sb2S3@CNP-T) in CNP matrix. Structural characterizations indicate that Sb2S3 particles have well dispersed in the pores of CNP matrix. Because of the introduction of porous and conductive CNP matrix to support Sb2S3, the hybrid catalyst exhibits lower charge transfer resistance at the catalyst/electrolyte interface and higher electrocatalytic activity. When used as counter electrode (CE) for dye-sensitized solar cells (DSSCs), devices using Sb2S3@CNP hybrid catalyst as CE produce fill factor of 67.6% and 66.3%, which is significantly higher than that using pristine Sb2S3 fabricated in our previous work (52.8%). Finally, the corresponding power conversion efficiencies reach 6.69% (Sb2S3@CNP-S) and 6.24% (Sb2S3@CNP-T), respectively, which are comparable to that using Pt CE measured under the same conditions (6.74%).

  2. Spectroscopic Studies of Doping and Charge Transfer in Single Walled Carbon Nanotubes and Lead Sulfide Quantum Dots

    Science.gov (United States)

    Haugen, Neale O.

    The use of single wall carbon nanotubes (SW-CNTs) in solar photovoltaic (PV) devices is a relatively new, but quickly growing field. SW-CNTs have found application as transparent front contacts, and high work function back contacts in thin film solar PV. For the utility of SW-CNTs to be fully realized, however, controllable and stable doping as well as long term protection from doping must be achieved. Spectroscopic techniques facilitate detailed investigations of the intrinsic and variable properties of semiconductor materials without the issues of contact deposition and the possibility of sample contamination. Detailed spectroscopic analysis of the doping induced changes in the optical properties of SW-CNTs has revealed normally hidden excited state transitions in large diameter single walled carbon nanotubes for the first time. Spectroscopic monitoring of the degree of doping in SW-CNTs made possible studies of the dopant complex desorption and readsorption energies and kinetics. The long term protection from doping of SW-CNTs exposed to ambient laboratory conditions was achieved as a result of the more detailed understanding of the doping processes and mechanisms yielded by these spectroscopic studies. The application of SW-CNTs to other roles in solar PV devices was another goal of this research. Efficient collection of photogenerated charge carriers in semiconductor quantum dot (QD) based solar photovoltaic devices has been limited primarily by the poor transport properties and high density of recombination sites in the QD films. Coupling semiconductor QDs to nanomaterials with better transport properties is one potential solution to the poor transport within the QD films. This portion of the work investigated the possibility of charge transfer occurring in nano-heterostructures (NHSs) of PbS QDs and SW-CNTs produced through spontaneous self-assembly in solution. Electronic coupling in the form of charge transfer from the QDs to the SW-CNTs is unambiguously

  3. Attack of carbonic anhydride and hydrogen sulfide on API class H cement slurries exposed to saline formation waters

    Directory of Open Access Journals (Sweden)

    Márquez, G.

    2011-09-01

    Full Text Available This paper discusses the attack of the major ions (sulfate, chloride, and magnesium and sour gases, present in natural gas (CO2 y SH2, on API class H cement, the type used in gas wells under high pressure and temperature. The effects of these chemical agents on this cement was simulated to study the physicochemical changes due to the action of sour gases and formation water. Cement specimens were immersed in neutral solutions containing fixed concentrations of the major ions inside Parr reactors. These solutions were analysed and XRD analyses were conducted for over two months to identify mineralogical variations from 14 to 60 days. The objective of this research was to determine the effects of the joint attack of major ions and sour gases on cement pastes. The main effects of both gases, jointly or separately, on cement durability were, respectively, the carbonation process and the leaching of some components.

    Se simuló la acción agresiva de los denominados iones fundamentales (sulfato, cloruro y magnesio y los gases agrios presentes en el gas natural (CO2 y H2S sobre un cemento API clase H utilizado en pozos gasíferos a presión y temperatura elevadas, al objeto de observar sus alteraciones fisicoquímicas por la acción combinada de tales gases y las aguas de formación. Se prepararon varias probetas del material cementante para su inmersión en disoluciones neutras, conteniendo los iones fundamentales en concentraciones fijas, dentro de reactores tipo Parr. Se analizaron durante más de dos meses una serie de disoluciones en contacto con el cemento utilizado; así como, mediante DRX, la evolución de la mineralogía de dicho material entre los 14 y los 60 días. Los principales efectos de ambos gases, en conjunto o por separado, sobre la durabilidad del cemento fueron, respectivamente, la formación de carbonato cálcico y la lixiviación de algunos componentes.

  4. Hydrogen sulfide in hemostasis: friend or foe?

    Science.gov (United States)

    Olas, Beata

    2014-06-25

    Hydrogen sulfide (H2S) is a well known toxic gas that is synthesized from the amino acids: cysteine (Cys) and homocysteine (Hcy) by three enzymes: cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE) and mercaptopyruvate sulfurtransferase (3-MST). Hydrogen sulfide, like carbon monoxide (CO) or nitric oxide (NO) is a signaling molecule in different biological systems, including the cardiovascular system. Moreover, hydrogen sulfide plays a role in the pathogenesis of various cardiovascular diseases. It modulates different elements of hemostasis (activation of blood platelet, and coagulation process) as well as proliferation and apoptosis of vascular smooth muscle cells. However, the biological role and the therapeutic potential of H2S is not clear. This review summarizes the different functions of hydrogen sulfide in hemostasis.

  5. Acute inhalation toxicity of carbonyl sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Benson, J.M.; Hahn, F.F.; Barr, E.B. [and others

    1995-12-01

    Carbonyl sulfide (COS), a colorless gas, is a side product of industrial procedures sure as coal hydrogenation and gasification. It is structurally related to and is a metabolite of carbon disulfide. COS is metabolized in the body by carbonic anhydrase to hydrogen sulfide (H{sub 2}S), which is thought to be responsible for COS toxicity. No threshold limit value for COS has been established. Results of these studies indicate COS (with an LC{sub 50} of 590 ppm) is slightly less acutely toxic than H{sub 2}S (LC{sub 50} of 440 ppm).

  6. Hydrogen sulfide: physiological properties and therapeutic potential in ischaemia.

    Science.gov (United States)

    Bos, Eelke M; van Goor, Harry; Joles, Jaap A; Whiteman, Matthew; Leuvenink, Henri G D

    2015-03-01

    Hydrogen sulfide (H2 S) has become a molecule of high interest in recent years, and it is now recognized as the third gasotransmitter in addition to nitric oxide and carbon monoxide. In this review, we discuss the recent literature on the physiology of endogenous and exogenous H2 S, focusing upon the protective effects of hydrogen sulfide in models of hypoxia and ischaemia.

  7. Interaction between hydrogen sulfide/cystathionine γ-lyase and carbon monoxide/heme oxygenase pathways in aortic smooth muscle cells

    Institute of Scientific and Technical Information of China (English)

    Hong-fang JIN; Jun-bao DU; Xiao-hui LI; Yan-fei WANG; Yin-fang LIANG; Chao-shu TANG

    2006-01-01

    Aim: To investigate the interaction between hydrogen sulfide (H2S)/cystathionine γ-lyase (CSE) and carbon monoxide (CO)/heme oxygenase (HO) pathways in aortic smooth muscle cells (ASMC). Methods: The ASMCs were divided into the following groups: (1) the control group; (2) the zinc protoporphyrin (ZnPP) 20 (μmol/L group; (3) the propargylglycine (PPG) 2 mmol/L, 4 mmol/L and 10 mmol/L groups; and (4) the sodium hydrosulfide (NaHS) 1×10-5 mol/L, 1×10-4 mol/L and 1×10-3 mol/L groups. Each of the groups was further divided into 6 h, 12 h, 18 h and 24 h subgroups. The CO level, represented by carboxyhemoglobin (HbCO) content was measured using a spectrophotometric method and H2S content was detected by a sensitive electrode method. CSE and HO-1 expressions were detected by Western blotting. Results: The H2S content in the medium and CSE expression by ASMC were markedly increased by ZnPP compared with the control group. HbCO content in the medium and HO-1 expression by the ASMC started strengthening following 24 h treatment with PPG at 2 mmol/L, but were further strengthened following 18 h and 24 h treatment with PPG at 4 mmol/L compared with the controls (P<0.01). PPG at 10 mmol/L increased the HbCO level in the medium following 18 h treatment and increased HO-1 expression by the ASMC following 12 h treatment. Moreover, NaHS at 1×10-5 mol/L and 1×10-4 mol/L decreased the HbCO level in the medium and HO-1 expression by the ASMC after 6 h and 12 h treatment, while NaHS at 1×10-3 mol/L decreased them at all time points of the treatments. Conclusion: The results suggested that endogenous CO/HO and H2S/CSE pathways inhibited each other in ASMC under physiological conditions.

  8. Endogenous hydrogen sulfide is associated with angiotensin II type 1 receptor in a rat model of carbon tetrachloride-induced hepatic fibrosis

    Science.gov (United States)

    FAN, HUI-NING; CHEN, NI-WEI; SHEN, WEI-LIN; ZHAO, XIANG-YUN; ZHANG, JING

    2015-01-01

    The present study aimed to investigate the effects of endogenous hydrogen sulfide (H2S) on the expression levels of angiotensin II type 1 receptor (AGTR1) in a rat model of carbon tetrachloride (CCl4)-induced hepatic fibrosis. A total of 56 Wistar rats were randomly divided into four groups: Normal control group, model group, sodium hydrosulfide (NaHS) group, and DL-propargylglycine (PAG) group. Hepatic fibrosis was induced by CCl4. The rats in the PAG group were intraperitoneally injected with PAG, an inhibitor of cystathionine-γ-lyase (CSE). The rats in the NaHS group were intraperitoneally injected with NaHS. An equal volume of saline solution was intraperitoneally injected into both the control and model groups. All rats were sacrificed at week three or four following treatment. The serum levels of hyaluronidase (HA), laminin protein (LN), procollagen III (PcIII), and collagen IV (cIV) were detected using ELISA. The serum levels of alanine transaminase (ALT), aspartate transaminase (AST), and albumin (ALB) were detected using an automatic biochemical analyzer. The liver mRNA expression levels of CSE were detected by reverse transcription-quantitative polymerase chain reaction. The liver expression levels of AGTR1 and the plasma expression levels of H2S were detected using western blot analyses. The results indicated that the severity of hepatic fibrosis, the serum expression levels of HA, LN, PcIII, cIV, ALT, and AST, the liver expression levels of CSE and AGTR1, and the plasma expression levels of H2S were significantly higher in the PAG group, as compared with the model group (P<0.05). Conversely, the expression levels of ALB were significantly lower in the PAG group, as compared with the model group. In addition, the severity of hepatic fibrosis, the serum expression levels of HA, LN, PcIII, cIV, ALT, and AST, the liver expression levels of CSE and AGTR1, and the plasma expression levels of H2S were significantly lower in the NaHS group, as compared with

  9. Hydrogen Sulfide--Mechanisms of Toxicity and Development of an Antidote.

    Science.gov (United States)

    Jiang, Jingjing; Chan, Adriano; Ali, Sameh; Saha, Arindam; Haushalter, Kristofer J; Lam, Wai-Ling Macrina; Glasheen, Megan; Parker, James; Brenner, Matthew; Mahon, Sari B; Patel, Hemal H; Ambasudhan, Rajesh; Lipton, Stuart A; Pilz, Renate B; Boss, Gerry R

    2016-02-15

    Hydrogen sulfide is a highly toxic gas-second only to carbon monoxide as a cause of inhalational deaths. Its mechanism of toxicity is only partially known, and no specific therapy exists for sulfide poisoning. We show in several cell types, including human inducible pluripotent stem cell (hiPSC)-derived neurons, that sulfide inhibited complex IV of the mitochondrial respiratory chain and induced apoptosis. Sulfide increased hydroxyl radical production in isolated mouse heart mitochondria and F2-isoprostanes in brains and hearts of mice. The vitamin B12 analog cobinamide reversed the cellular toxicity of sulfide, and rescued Drosophila melanogaster and mice from lethal exposures of hydrogen sulfide gas. Cobinamide worked through two distinct mechanisms: direct reversal of complex IV inhibition and neutralization of sulfide-generated reactive oxygen species. We conclude that sulfide produces a high degree of oxidative stress in cells and tissues, and that cobinamide has promise as a first specific treatment for sulfide poisoning.

  10. The Evolution of Sulfide Tolerance in the Cyanobacteria

    Science.gov (United States)

    Miller, Scott R.; Bebout, Brad M.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Understanding how the function of extant microorganisms has recorded both their evolutionary histories and their past interactions with the environment is a stated goal of astrobiology. We are taking a multidisciplinary approach to investigate the diversification of sulfide tolerance mechanisms in the cyanobacteria, which vary both in their degree of exposure to sulfide and in their capacity to tolerate this inhibitor of photosynthetic electron transport. Since conditions were very reducing during the first part of Earth's history and detrital sulfides have been found in Archean sediments, mechanisms conferring sulfide tolerance may have been important for the evolutionary success of the ancestors of extant cyanobacteria. Two tolerance mechanisms have been identified in this group: (1) resistance of photosystem II, the principal target of sulfide toxicity; and (2) maintenance of the ability to fix carbon despite photosystem II inhibition by utilizing sulfide as an electron donor in photosystem I - dependent, anoxygenic photosynthesis. We are presently collecting comparative data on aspects of sulfide physiology for laboratory clones isolated from a variety of habitats. These data will be analyzed within a phylogenetic framework inferred from molecular sequence data collected for these clones to test how frequently different mechanisms of tolerance have evolved and which tolerance mechanism evolved first. In addition, by analyzing these physiological data together with environmental sulfide data collected from our research sites using microelectrodes, we can also test whether the breadth of an organism's sulfide tolerance can be predicted from the magnitude of variation in environmental sulfide concentration it has experienced in its recent evolutionary past and whether greater average sulfide concentration and/or temporal variability in sulfide favors the evolution of a particular mechanism of sulfide tolerance.

  11. Microbial Fuel Cells for Sulfide Removal

    NARCIS (Netherlands)

    Rabaey, K.; Sompel, van de S.; Maignien, L.; Boon, N.; Aelterman, P.; Clauwaert, P.; Schamphelaire, de L.; The Pham, H.; Vermeulen, J.; Verhaege, M.; Lens, P.N.L.; Verstraete, W.

    2006-01-01

    Thus far, microbial fuel cells (MFCs) have been used to convert carbon-based substrates to electricity. However, sulfur compounds are ubiquitously present in organic waste and wastewater. In this study, a MFC with a hexacyanoferrate cathodic electrolyte was used to convert dissolved sulfide to eleme

  12. Molybdenum sulfide/carbide catalysts

    Science.gov (United States)

    Alonso, Gabriel; Chianelli, Russell R.; Fuentes, Sergio; Torres, Brenda

    2007-05-29

    The present invention provides methods of synthesizing molybdenum disulfide (MoS.sub.2) and carbon-containing molybdenum disulfide (MoS.sub.2-xC.sub.x) catalysts that exhibit improved catalytic activity for hydrotreating reactions involving hydrodesulfurization, hydrodenitrogenation, and hydrogenation. The present invention also concerns the resulting catalysts. Furthermore, the invention concerns the promotion of these catalysts with Co, Ni, Fe, and/or Ru sulfides to create catalysts with greater activity, for hydrotreating reactions, than conventional catalysts such as cobalt molybdate on alumina support.

  13. A lithium-ion sulfur battery based on a carbon-coated lithium-sulfide cathode and an electrodeposited silicon-based anode.

    Science.gov (United States)

    Agostini, Marco; Hassoun, Jusef; Liu, Jun; Jeong, Moongook; Nara, Hiroki; Momma, Toshiyuki; Osaka, Tetsuya; Sun, Yang-Kook; Scrosati, Bruno

    2014-07-23

    In this paper, we report a lithium-ion battery employing a lithium sulfide cathode and a silicon-based anode. The high capacity of the silicon anode and the high efficiency and cycling rate of the lithium sulfide cathode allowed optimal full cell balance. We show in fact that the battery operates with a very stable capacity of about 280 mAh g(-1) at an average voltage of 1.4 V. To the best of our knowledge, this battery is one of the rare examples of lithium-metal-free sulfur battery. Considering the high theoretical capacity of the employed electrodes, we believe that the battery here reported may be of potential interest as high-energy, safe, and low-cost power source for electric vehicles.

  14. Renewable-surface sol-gel derived carbon ceramic electrode fabricated by [Ru(bpy)(tpy)Cl]PF6 and its application as an amperometric sensor for sulfide and sulfur oxoanions.

    Science.gov (United States)

    Salimi, Abdollah; Pourbeyram, Sima; Amini, Mohamad Kazem

    2002-12-01

    A highly sensitive and fast responding sensor for the determination of thiosulfate, sulfite, sulfide and dithionite is described. It consists of a chemically modified carbon ceramic composite electrode (CCE) containing [Ru(bpy)(tpy)Cl]PF6 complex that was constructed by the sol-gel technique. A reversible redox couple of Ru(II)/Ru(III) was observed as a solute in acetonitrile solution and as a component of carbon based conducting composite electrode. Electrochemical behavior and stability of modified CCE were investigated by cyclic voltametry, the apparent electron transfer rate constant (kappa(S)) and transfer coefficient (a) were determined by cyclic voltametry which were about 28 s(-1) and 0.43 respectively. Electrocatalytic oxidation of S(2-), SO3(2-), S2O4(2-) and S2O3(2-) were effective at the modified electrode at significantly reduced overpotentials and in the pH range 1-11. Optimum pH values for amperometric detection of thiosulfate, dithionite, sulfide and sulfite are 7, 9, 2 and 2. Under the optimized conditions the calibration curves are linear in the concentration ranges 1-500, 3-80, 2-90 and 1-100 microM for S2O3(2-), SO3(2-), S2- and S2O4(2-) determination. The detection limit (signal to noise is 3) and sensitivity are 0.5 and 12, 2.8 and 6, 1.6 and 8, and 0.65 microM and 80 nA microM(-1) for thiosulfate, sulfite, sulfide and dithionite detection. The modified carbon ceramic electrode doped with Ru-complex shows good reproducibility, a short response time (t 6 month) and especially good surface renewability by simple mechanical polishing (RSD for eight successive polishing is 2%). The advantages of this sulfur compound amperometric detector based on ruthenium doped CCE are high sensitivity, inherent stability at a broader pH range, excellent catalytic activity, less expense and simplicity of preparation in comparison with recently published papers. This sensor can be used as a chromatographic detector for analysis of sulfur derivatives.

  15. Study on gold extraction from double refractory gold ores with high sulfide and carbon content%高硫高碳双重难处理金矿石提金工艺研究

    Institute of Scientific and Technical Information of China (English)

    石吉友; 赵喜民

    2014-01-01

    针对某高硫高碳双重难处理金矿石,采用常规浮选法、全泥氰化炭浆法和全泥氰化炭浸法进行处理,金浸出率均很低。最终,通过采用钝化-全泥氰化炭浸工艺处理该矿石,获得了较好指标,金浸出率达到82.83%。%Gold leaching rates are frustrating when conventional flotation ,all-sliming cyanidation-CIP and all-sli-ming cyanidation-CIL method are applied in the treatment of some double refractory gold ores with high sulfide and carbon content.Finally,an inactivation -all-sliming cyanidation-CIL process is used,achieving better indexes with gold leaching rate reaching 82.83 %.

  16. Sulfide and methane production in sewer sediments.

    Science.gov (United States)

    Liu, Yiwen; Ni, Bing-Jie; Ganigué, Ramon; Werner, Ursula; Sharma, Keshab R; Yuan, Zhiguo

    2015-03-01

    Recent studies have demonstrated significant sulfide and methane production by sewer biofilms, particularly in rising mains. Sewer sediments in gravity sewers are also biologically active; however, their contribution to biological transformations in sewers is poorly understood at present. In this study, sediments collected from a gravity sewer were cultivated in a laboratory reactor fed with real wastewater for more than one year to obtain intact sediments. Batch test results show significant sulfide production with an average rate of 9.20 ± 0.39 g S/m(2)·d from the sediments, which is significantly higher than the areal rate of sewer biofilms. In contrast, the average methane production rate is 1.56 ± 0.14 g CH4/m(2)·d at 20 °C, which is comparable to the areal rate of sewer biofilms. These results clearly show that the contributions of sewer sediments to sulfide and methane production cannot be ignored when evaluating sewer emissions. Microsensor and pore water measurements of sulfide, sulfate and methane in the sediments, microbial profiling along the depth of the sediments and mathematical modelling reveal that sulfide production takes place near the sediment surface due to the limited penetration of sulfate. In comparison, methane production occurs in a much deeper zone below the surface likely due to the better penetration of soluble organic carbon. Modelling results illustrate the dependency of sulfide and methane productions on the bulk sulfate and soluble organic carbon concentrations can be well described with half-order kinetics.

  17. Interstellar hydrogen sulfide.

    Science.gov (United States)

    Thaddeus, P.; Kutner, M. L.; Penzias, A. A.; Wilson, R. W.; Jefferts, K. B.

    1972-01-01

    Hydrogen sulfide has been detected in seven Galactic sources by observation of a single line corresponding to the rotational transition from the 1(sub 10) to the 1(sub 01) levels at 168.7 GHz. The observations show that hydrogen sulfide is only a moderately common interstellar molecule comparable in abundance to H2CO and CS, but somewhat less abundant than HCN and much less abundant than CO.

  18. Bio-orthogonal "click-and-release" donation of caged carbonyl sulfide (COS) and hydrogen sulfide (H2S).

    Science.gov (United States)

    Steiger, Andrea K; Yang, Yang; Royzen, Maksim; Pluth, Michael D

    2017-01-24

    Hydrogen sulfide (H2S) is an important biomolecule with high therapeutic potential. Here we leverage the inverse-electron demand Diels-Alder (IEDDA) click reaction between a thiocarbamate-functionalized trans-cyclooctene and a tetrazine to deliver carbonyl sulfide (COS), which is quickly converted to H2S by the uniquitous enzyme carbonic anhydrase (CA), thus providing a new strategy for bio-orthogonal COS/H2S donation.

  19. Hydrogen sulfide prodrugs—a review

    Directory of Open Access Journals (Sweden)

    Yueqin Zheng

    2015-09-01

    Full Text Available Hydrogen sulfide (H2S is recognized as one of three gasotransmitters together with nitric oxide (NO and carbon monoxide (CO. As a signaling molecule, H2S plays an important role in physiology and shows great potential in pharmaceutical applications. Along this line, there is a need for the development of H2S prodrugs for various reasons. In this review, we summarize different H2S prodrugs, their chemical properties, and some of their potential therapeutic applications.

  20. Hydrogen sulfide prodrugs—a review

    Science.gov (United States)

    Zheng, Yueqin; Ji, Xingyue; Ji, Kaili; Wang, Binghe

    2015-01-01

    Hydrogen sulfide (H2S) is recognized as one of three gasotransmitters together with nitric oxide (NO) and carbon monoxide (CO). As a signaling molecule, H2S plays an important role in physiology and shows great potential in pharmaceutical applications. Along this line, there is a need for the development of H2S prodrugs for various reasons. In this review, we summarize different H2S prodrugs, their chemical properties, and some of their potential therapeutic applications. PMID:26579468

  1. Simulation of sulfide buildup in wastewater and atmosphere of sewer networks.

    Science.gov (United States)

    Nielsen, A H; Yongsiri, C; Hvitved-Jacobsen, T; Vollertsen, J

    2005-01-01

    A model concept for prediction of sulfide buildup in sewer networks is presented. The model concept is an extension to--and a further development of--the WATS model (Wastewater Aerobic-anaerobic Transformations in Sewers), which has been developed by Hvitved-Jacobsen and co-workers at Aalborg University. In addition to the sulfur cycle, the WATS model simulates changes in dissolved oxygen and carbon fractions of different biodegradability. The sulfur cycle was introduced via six processes: 1. sulfide production taking place in the biofilm covering the permanently wetted sewer walls; 2. biological sulfide oxidation in the permanently wetted biofilm; 3. chemical and biological sulfide oxidation in the water phase; 4. sulfide precipitation with metals present in the wastewater; 5. emission of hydrogen sulfide to the sewer atmosphere and 6. adsorption and oxidation of hydrogen sulfide on the moist sewer walls where concrete corrosion may take place.

  2. Adequate hydrogen sulfide, healthy circulation

    Institute of Scientific and Technical Information of China (English)

    DU Jun-bao; CHEN Stella; JIN Hong-fang; TANG Chao-shu

    2011-01-01

    Previously,hydrogen sulfide (H2S) was considered to be a toxic gas.However,recently it was discovered that it could be produced in mammals and even in plants,throughtheproductionandmetabolismof sulfur-containing amino acids.In mammals,H2S is mainly catalyzed by cystathionine-γ-lyase (CSE),cystathionin-β-lyase (CBS) and 3-mercaptopyruvate sulfurtransferase (MPST) with the substrate of L-cysteine.Endogenous H2S exerts many important physiological and pathophysiological functions,including hypotensive action,vasorelaxation,myocardial dilation,inhibition of smooth muscle cell proliferation,and antioxidatve actions.Importantly,it plays a very important role in the pathogenesis of systemic hypertension,pulmonary hypertension,atherosclerosis,myocardialinjury,angiogenesis,hyperhomocysteinemi aandshock.Therefore,H2S is now being considered to be a novel gasotransmitter after nitric oxide and carbon monoxide in the regulation of circulatory system.

  3. 1D Ni-Co oxide and sulfide nanoarray/carbon aerogel hybrid nanostructures for asymmetric supercapacitors with high energy density and excellent cycling stability.

    Science.gov (United States)

    Hao, Pin; Tian, Jian; Sang, Yuanhua; Tuan, Chia-Chi; Cui, Guanwei; Shi, Xifeng; Wong, C P; Tang, Bo; Liu, Hong

    2016-09-15

    The fabrication of supercapacitor electrodes with high energy density and excellent cycling stability is still a great challenge. A carbon aerogel, possessing a hierarchical porous structure, high specific surface area and electrical conductivity, is an ideal backbone to support transition metal oxides and bring hope to prepare electrodes with high energy density and excellent cycling stability. Therefore, NiCo2S4 nanotube array/carbon aerogel and NiCo2O4 nanoneedle array/carbon aerogel hybrid supercapacitor electrode materials were synthesized by assembling Ni-Co precursor needle arrays on the surface of the channel walls of hierarchical porous carbon aerogels derived from chitosan in this study. The 1D nanostructures grow on the channel surface of the carbon aerogel vertically and tightly, contributing to the enhanced electrochemical performance with ultrahigh energy density. The energy density of NiCo2S4 nanotube array/carbon aerogel and NiCo2O4 nanoneedle array/carbon aerogel hybrid asymmetric supercapacitors can reach up to 55.3 Wh kg(-1) and 47.5 Wh kg(-1) at a power density of 400 W kg(-1), respectively. These asymmetric devices also displayed excellent cycling stability with a capacitance retention of about 96.6% and 92% over 5000 cycles.

  4. Sulfide oxidation in a biofilter

    DEFF Research Database (Denmark)

    Pedersen, Claus Lunde; Dezhao, Liu; Hansen, Michael Jørgen;

    Observed hydrogen sulfide uptake rates in a biofilter treating waste air from a pig farm were too high to be explained within conventional limits of sulfide solubility, diffusion in a biofilm and bacterial metabolism. Clone libraries of 16S and 18S rRNA genes from the biofilter found no sulfide o...... higher hydrogen sulfide uptake followed by oxidation catalyzed by iron-containing enzymes such as cytochrome c oxidase in a process uncoupled from energy conservation....

  5. Sulfide oxidation in a biofilter

    DEFF Research Database (Denmark)

    Pedersen, Claus Lunde; Liu, Dezhao; Hansen, Michael Jørgen;

    2012-01-01

    Observed hydrogen sulfide uptake rates in a biofilter treating waste air from a pig farm were too high to be explained within conventional limits of sulfide solubility, diffusion in a biofilm and bacterial metabolism. Clone libraries of 16S and 18S rRNA genes from the biofilter found no sulfide o...... higher hydrogen sulfide uptake followed by oxidation catalyzed by iron-containing enzymes such as cytochrome c oxidase in a process uncoupled from energy conservation....

  6. Effect of concentration of lithium ions on the voltammetric responses of nitro-substituted aromatic sulfides in dimethylformamide on glassy carbon electrodes

    Science.gov (United States)

    Chellammal, S.; Noel, M.; Anantharaman, P. N.

    Lithium salts are used as supporting electrolytes and ion-pair forming reagents during voltammetric investigations in aprotic solvents. In the present work, these ions are found to have a significant influence on the voltammetric responses of aromatic sulfides in dimethylformamide given their concentration and the cathodic potential limits applied. At very low concentrations (reduction of nitro groups on the electrode surface. This is the conventional lithium ion-pair formation effect reported in the literature. With increasing lithium ion concentration and increasing cathodic limit, the ion-pairs tend to form an insoluble salt film on the electrode surface. This leads to inhibition of further electron transfer. The inhibiting effect does not seem to correlate with the size of the reactant organic molecule involved. At cathodic potential limits exceeding - 2 V, lithium ions appear to undergo direct reduction and subsequent reaction with trace levels of water in the solvent to produce a passive LiOH layer. This inhibits all further electron transfer.

  7. Sulfide elimination by intermittent nitrate dosing in sewer sediments

    Institute of Scientific and Technical Information of China (English)

    Yanchen Liu; Chen Wu; Xiaohong Zhou; David Z.Zhu; Hanchang Shi

    2015-01-01

    The formation of hydrogen sulfide in biofilms and sediments in sewer systems can cause severe pipe corrosions and health hazards,and requires expensive programs for its prevention.The aim of this study is to propose a new control strategy and the optimal condition for sulfide elimination by intermittent nitrate dosing in sewer sediments.The study was carried out based on lab-scale experiments and batch tests using real sewer sediments.The intermittent nitrate dosing mode and the optimal control condition were investigated.The results indicated that the sulfide-intermittent-elimination strategy by nitrate dosing is advantageous for controlling sulfide accumulation in sewer sediment.The oxidation-reduction potential is a sensitive indicator parameter that can reflect the control effect and the minimum N/S (nitrate/sulfide)ratio with slight excess nitrate is necessary for optimal conditions ofefficient sulfide control with lower carbon source loss.The opth-nal control condition is feasible for the sulfide elimination in sewer systems.

  8. Use of hydrochloric acid for determinining solid-phase arsenic partitioning in sulfidic sediments.

    Science.gov (United States)

    Wilkin, Richard T; Ford, Robert G

    2002-11-15

    We examined the use of room-temperature hydrochloric acid (1-6 M) and salt solutions of magnesium chloride, sodium carbonate, and sodium sulfide for the removal of arsenic from synthetic iron monosulfides and contaminated sediments containing acid-volatile sulfides (AVS). Results indicate that acid-soluble arsenic reacts with H2S released from AVS phases and precipitates at low pH as disordered orpiment or alacranite. Arsenic sulfide precipitation is consistent with geochemical modeling in that conditions during acid extraction are predicted to be oversaturated with respect to orpiment, realgar, or both. Binding of arsenic with sulfide at low pH is sufficiently strong that 6 M HCl will not keep spiked arsenic in the dissolved fraction. Over a wide range of AVS concentrations and molar [As]/[AVS] ratios, acid extraction of arsenic from sulfide-bearing sediments will give biased results that overestimate the stability or underestimate the bioavailability of sediment-bound arsenic. Alkaline solutions of sodium sulfide and sodium carbonate are efficient in removing arsenic from arsenic sulfides and mixed iron-arsenic sulfides because of the high solubility of arsenic at alkaline pH, the formation of stable arsenic complexes with sulfide or carbonate, or both.

  9. Sulfide detoxification in plant mitochondria.

    Science.gov (United States)

    Birke, Hannah; Hildebrandt, Tatjana M; Wirtz, Markus; Hell, Rüdiger

    2015-01-01

    In contrast to animals, which release the signal molecule sulfide in small amounts from cysteine and its derivates, phototrophic eukaryotes generate sulfide as an essential intermediate of the sulfur assimilation pathway. Additionally, iron-sulfur cluster turnover and cyanide detoxification might contribute to the release of sulfide in mitochondria. However, sulfide is a potent inhibitor of cytochrome c oxidase in mitochondria. Thus, efficient sulfide detoxification mechanisms are required in mitochondria to ensure adequate energy production and consequently survival of the plant cell. Two enzymes have been recently described to catalyze sulfide detoxification in mitochondria of Arabidopsis thaliana, O-acetylserine(thiol)lyase C (OAS-TL C), and the sulfur dioxygenase (SDO) ethylmalonic encephalopathy protein 1 (ETHE1). Biochemical characterization of sulfide producing and consuming enzymes in mitochondria of plants is fundamental to understand the regulatory network that enables mitochondrial sulfide homeostasis under nonstressed and stressed conditions. In this chapter, we provide established protocols to determine the activity of the sulfide releasing enzyme β-cyanoalanine synthase as well as sulfide-consuming enzymes OAS-TL and SDO. Additionally, we describe a reliable and efficient method to purify OAS-TL proteins from plant material.

  10. INVESTIGATIONS ON BIOCHEMICAL PURIFICATION OF GROUND WATER FROM HYDROGEN SULFIDE

    Directory of Open Access Journals (Sweden)

    Yu. P. Sedlukho

    2015-01-01

    Full Text Available The paper considers problems and features of biochemical removal of hydrogen sulfide from ground water. The analysis of existing methods for purification of ground water from hydrogen sulfide has been given in the paper. The paper has established shortcomings of physical and chemical purification of ground water. While using aeration methods for removal of hydrogen sulfide formation of colloidal sulfur that gives muddiness and opalescence to water occurs due to partial chemical air oxidation. In addition to this violation of sulfide-carbonate equilibrium taking place in the process of aeration due to desorption of H2S and CO2, often leads to clogging of degasifier nozzles with formed CaCO3 that causes serious operational problems. Chemical methods require relatively large flow of complex reagent facilities, storage facilities and transportation costs.In terms of hydrogen sulfide ground water purification the greatest interest is given to the biochemical method. Factors deterring widespread application of the biochemical method is its insufficient previous investigation and necessity to execute special research in order to determine optimal process parameters while purifying groundwater of a particular water supply source. Biochemical methods for oxidation of sulfur compounds are based on natural biological processes that ensure natural sulfur cycle. S. Vinogradsky has established a two-stage mechanism for oxidation of hydrogen sulfide with sulfur bacteria (Beggiatoa. The first stage presupposes oxidation of hydrogen sulphide to elemental sulfur which is accumulating in the cytoplasm in the form of globules. During the second stage sulfur bacteria begin to oxidize intracellular sulfur to sulfuric acid due to shortage of hydrogen sulfide.The paper provides the results of technological tests of large-scale pilot plants for biochemical purification of groundwater from hydrogen sulfide in semi-industrial conditions. Dependences of water quality

  11. Hydrogen sulfide : physiological properties and therapeutic potential in ischaemia

    NARCIS (Netherlands)

    Bos, Eelke M.; van Goor, Harry; Joles, Jaap A.; Whiteman, Matthew; Leuvenink, Henri G. D.

    2015-01-01

    Hydrogen sulfide (H2S) has become a molecule of high interest in recent years, and it is now recognized as the third gasotransmitter in addition to nitric oxide and carbon monoxide. In this review, we discuss the recent literature on the physiology of endogenous and exogenous H2S, focusing upon the

  12. A hybrid artificial neural network and particle swarm optimization for prediction of removal of hazardous dye brilliant green from aqueous solution using zinc sulfide nanoparticle loaded on activated carbon

    Science.gov (United States)

    Ghaedi, M.; Ansari, A.; Bahari, F.; Ghaedi, A. M.; Vafaei, A.

    2015-02-01

    In the present study, zinc sulfide nanoparticle loaded on activated carbon (ZnS-NP-AC) simply was synthesized in the presence of ultrasound and characterized using different techniques such as SEM and BET analysis. Then, this material was used for brilliant green (BG) removal. To dependency of BG removal percentage toward various parameters including pH, adsorbent dosage, initial dye concentration and contact time were examined and optimized. The mechanism and rate of adsorption was ascertained by analyzing experimental data at various time to conventional kinetic models such as pseudo-first-order and second order, Elovich and intra-particle diffusion models. Comparison according to general criterion such as relative error in adsorption capacity and correlation coefficient confirm the usability of pseudo-second-order kinetic model for explanation of data. The Langmuir models is efficiently can explained the behavior of adsorption system to give full information about interaction of BG with ZnS-NP-AC. A multiple linear regression (MLR) and a hybrid of artificial neural network and partial swarm optimization (ANN-PSO) model were used for prediction of brilliant green adsorption onto ZnS-NP-AC. Comparison of the results obtained using offered models confirm higher ability of ANN model compare to the MLR model for prediction of BG adsorption onto ZnS-NP-AC. Using the optimal ANN-PSO model the coefficient of determination (R2) were 0.9610 and 0.9506; mean squared error (MSE) values were 0.0020 and 0.0022 for the training and testing data set, respectively.

  13. A hybrid artificial neural network and particle swarm optimization for prediction of removal of hazardous dye brilliant green from aqueous solution using zinc sulfide nanoparticle loaded on activated carbon.

    Science.gov (United States)

    Ghaedi, M; Ansari, A; Bahari, F; Ghaedi, A M; Vafaei, A

    2015-02-25

    In the present study, zinc sulfide nanoparticle loaded on activated carbon (ZnS-NP-AC) simply was synthesized in the presence of ultrasound and characterized using different techniques such as SEM and BET analysis. Then, this material was used for brilliant green (BG) removal. To dependency of BG removal percentage toward various parameters including pH, adsorbent dosage, initial dye concentration and contact time were examined and optimized. The mechanism and rate of adsorption was ascertained by analyzing experimental data at various time to conventional kinetic models such as pseudo-first-order and second order, Elovich and intra-particle diffusion models. Comparison according to general criterion such as relative error in adsorption capacity and correlation coefficient confirm the usability of pseudo-second-order kinetic model for explanation of data. The Langmuir models is efficiently can explained the behavior of adsorption system to give full information about interaction of BG with ZnS-NP-AC. A multiple linear regression (MLR) and a hybrid of artificial neural network and partial swarm optimization (ANN-PSO) model were used for prediction of brilliant green adsorption onto ZnS-NP-AC. Comparison of the results obtained using offered models confirm higher ability of ANN model compare to the MLR model for prediction of BG adsorption onto ZnS-NP-AC. Using the optimal ANN-PSO model the coefficient of determination (R(2)) were 0.9610 and 0.9506; mean squared error (MSE) values were 0.0020 and 0.0022 for the training and testing data set, respectively.

  14. 一氧化碳对硫化氢舒张大鼠肺动脉作用的影响%THE EFFECTS OF CARBON MONOXIDE ON THE RAT PULMONARY ARTERY RELAXATION RESPONSES TO HYDROGEN SULFIDE

    Institute of Scientific and Technical Information of China (English)

    张晓静; 孟祥艳; 黄新莉; 戴鸿雁; 韦鹏; 凌亦凌

    2010-01-01

    目的 观察在脂多糖(lipopolysaccharide,LPS)诱导下,一氧化碳(carbon monoxide,CO)对硫化氢(hydrogen sulfide,H2S) 舒张肺动脉作用的影响.方法 气管内滴注生理盐水或LPS后,制备肺动脉环(pulmonary artery rings,PARs),应用血管环张力测定技术,分别在给予CO供体氯血红素(hemin,Hm) 或血红素氧合酶1抑制剂锌原卟啉9(zinc protoporphyrin-IX,ZnPP-IX)的条件下,从离体水平观察PARs对H2S供体硫氢化钠(sodium hydrosulfide,NaHS)舒张反应变化,同时检测出肺血(out-going pulmonary blood,OPB)和入肺血(in-flowing pulmonary blood,IPB)中碳氧血红蛋白(carboxyhemoglobin,COHb)含量,以其差值反映肺循环CO生成的水平.结果 滴注LPS 4 h和8 h后,用Hm孵育PARs后,PARs对NaHS的累积浓度舒张反应较孵育前显著增强(P0.05).结论 在LPS诱导下,CO可以增强H2S舒张肺动脉的作用.

  15. Altered Sulfide (H2S) Metabolism in Ethylmalonic Encephalopathy

    OpenAIRE

    2013-01-01

    Hydrogen sulfide (sulfide, H2S) is a colorless, water-soluble gas with a typical smell of rotten eggs. In the past, it has been investigated for its role as a potent toxic gas emanating from sewers and swamps or as a by-product of industrial processes. At high concentrations, H2S is a powerful inhibitor of cytochrome c oxidase; in trace amounts, it is an important signaling molecule, like nitric oxide (NO) and carbon monoxide (CO), together termed “gasotransmitters.” This review will cover th...

  16. Simulation study to determine the feasibility of injecting hydrogen sulfide, carbon dioxide and nitrogen gas injection to improve gas and oil recovery oil-rim reservoir

    Science.gov (United States)

    Eid, Mohamed El Gohary

    This study is combining two important and complicated processes; Enhanced Oil Recovery, EOR, from the oil rim and Enhanced Gas Recovery, EGR from the gas cap using nonhydrocarbon injection gases. EOR is proven technology that is continuously evolving to meet increased demand and oil production and desire to augment oil reserves. On the other hand, the rapid growth of the industrial and urban development has generated an unprecedented power demand, particularly during summer months. The required gas supplies to meet this demand are being stretched. To free up gas supply, alternative injectants to hydrocarbon gas are being reviewed to support reservoir pressure and maximize oil and gas recovery in oil rim reservoirs. In this study, a multi layered heterogeneous gas reservoir with an oil rim was selected to identify the most optimized development plan for maximum oil and gas recovery. The integrated reservoir characterization model and the pertinent transformed reservoir simulation history matched model were quality assured and quality checked. The development scheme is identified, in which the pattern and completion of the wells are optimized to best adapt to the heterogeneity of the reservoir. Lateral and maximum block contact holes will be investigated. The non-hydrocarbon gases considered for this study are hydrogen sulphide, carbon dioxide and nitrogen, utilized to investigate miscible and immiscible EOR processes. In November 2010, re-vaporization study, was completed successfully, the first in the UAE, with an ultimate objective is to examine the gas and condensate production in gas reservoir using non hydrocarbon gases. Field development options and proces schemes as well as reservoir management and long term business plans including phases of implementation will be identified and assured. The development option that maximizes the ultimate recovery factor will be evaluated and selected. The study achieved satisfactory results in integrating gas and oil

  17. Selective Sulfidation of Lead Smelter Slag with Sulfur

    Science.gov (United States)

    Han, Junwei; Liu, Wei; Wang, Dawei; Jiao, Fen; Qin, Wenqing

    2016-02-01

    The selective sulfidation of lead smelter slag with sulfur was studied. The effects of temperature, sulfur dosage, carbon, and Na salts additions were investigated based on thermodynamic calculation. The results indicated that more than 96 pct of zinc in the slag could be converted into sulfides. Increasing temperature, sulfur dosage, or Na salts dosage was conducive to the sulfidation of the zinc oxides in the slag. High temperature and excess Na salts would result in the more consumption of carbon and sulfur. Carbon addition not only promoted the selective sulfidation but reduced the sulfur dosage and eliminated the generation of SO2. Iron oxides had a buffering role on the sulfur efficient utilization. The transformation of sphalerite to wurtzite was feasible under reducing condition at high temperature, especially above 1273 K (1000 °C). The growth of ZnS particles largely depended upon the roasting temperature. They were significantly increased when the temperature was above 1273 K (1000 °C), which was attributed to the formation of a liquid phase.

  18. In Situ Gene Expression Responsible for Sulfide Oxidation and CO2 Fixation of an Uncultured Large Sausage-Shaped Aquificae Bacterium in a Sulfidic Hot Spring.

    Science.gov (United States)

    Tamazawa, Satoshi; Yamamoto, Kyosuke; Takasaki, Kazuto; Mitani, Yasuo; Hanada, Satoshi; Kamagata, Yoichi; Tamaki, Hideyuki

    2016-06-25

    We investigated the in situ gene expression profile of sulfur-turf microbial mats dominated by an uncultured large sausage-shaped Aquificae bacterium, a key metabolic player in sulfur-turfs in sulfidic hot springs. A reverse transcription-PCR analysis revealed that the genes responsible for sulfide, sulfite, and thiosulfate oxidation and carbon fixation via the reductive TCA cycle were continuously expressed in sulfur-turf mats taken at different sampling points, seasons, and years. These results suggest that the uncultured large sausage-shaped bacterium has the ability to grow chemolithoautotrophically and plays key roles as a primary producer in the sulfidic hot spring ecosystem in situ.

  19. Sulfide intrusion and detoxification in Zostera marina

    DEFF Research Database (Denmark)

    Hasler-Sheetal, Harald; Holmer, Marianne

    2014-01-01

    indicating a possible role of sulfide in the sulfur nutrition beside the detoxification function. Our results suggest different adaptations of Z. marina to reduced sediments and sulfide intrusion ranging from bacterial and chemical reoxidation of sulfide to sulfate to incorporation of sulfide into organic...

  20. Altered Sulfide (H2S) Metabolism in Ethylmalonic Encephalopathy

    Science.gov (United States)

    Tiranti, Valeria; Zeviani, Massimo

    2013-01-01

    Hydrogen sulfide (sulfide, H2S) is a colorless, water-soluble gas with a typical smell of rotten eggs. In the past, it has been investigated for its role as a potent toxic gas emanating from sewers and swamps or as a by-product of industrial processes. At high concentrations, H2S is a powerful inhibitor of cytochrome c oxidase; in trace amounts, it is an important signaling molecule, like nitric oxide (NO) and carbon monoxide (CO), together termed “gasotransmitters.” This review will cover the physiological role and the pathogenic effects of H2S, focusing on ethylmalonic encephalopathy, a human mitochondrial disorder caused by genetic abnormalities of sulfide metabolism. We will also discuss the options that are now conceivable for preventing genetically driven chronic H2S toxicity, taking into account that a complete understanding of the physiopathology of H2S has still to be achieved. PMID:23284046

  1. Altered sulfide (H(2)S) metabolism in ethylmalonic encephalopathy.

    Science.gov (United States)

    Tiranti, Valeria; Zeviani, Massimo

    2013-01-01

    Hydrogen sulfide (sulfide, H(2)S) is a colorless, water-soluble gas with a typical smell of rotten eggs. In the past, it has been investigated for its role as a potent toxic gas emanating from sewers and swamps or as a by-product of industrial processes. At high concentrations, H(2)S is a powerful inhibitor of cytochrome c oxidase; in trace amounts, it is an important signaling molecule, like nitric oxide (NO) and carbon monoxide (CO), together termed "gasotransmitters." This review will cover the physiological role and the pathogenic effects of H(2)S, focusing on ethylmalonic encephalopathy, a human mitochondrial disorder caused by genetic abnormalities of sulfide metabolism. We will also discuss the options that are now conceivable for preventing genetically driven chronic H(2)S toxicity, taking into account that a complete understanding of the physiopathology of H(2)S has still to be achieved.

  2. A novel method for improving cerussite sulfidization

    Institute of Scientific and Technical Information of China (English)

    Qi-cheng Feng; Shu-ming Wen; Wen-juan Zhao; Qin-bo Cao; Chao L

    2016-01-01

    Evaluation of flotation behavior, solution measurements, and surface analyses were performed to investigate the effects of chloride ion addition on the sulfidization of cerussite in this study. Micro-flotation tests indicate that the addition of chloride ions prior to sulfidization can significantly increase the flotation recovery of cerussite, which is attributed to the formation of more lead sulfide species on the mineral surface. Solution measurement results suggest that the addition of chloride ions prior to sulfidization induces the transformation of more sul-fide ions from pulp solution onto the mineral surface by the formation of more lead sulfide species. X-ray diffraction and energy-dispersive spectroscopy indicate that more lead sulfide species form on the mineral surface when chloride ions are added prior to sulfidization. These results demonstrate that the addition of chloride ions prior to sulfidization can significantly improve the sulfidization of cerussite, thereby enhancing the flotation performance.

  3. Prevention of sulfide oxidation in sulfide-rich waste rock

    Science.gov (United States)

    Nyström, Elsa; Alakangas, Lena

    2015-04-01

    The ability to reduce sulfide oxidation in waste rock after mine closure is a widely researched area, but to reduce and/or inhibit the oxidation during operation is less common. Sulfide-rich (ca 30 % sulfur) waste rock, partially oxidized, was leached during unsaturated laboratory condition. Trace elements such as As and Sb were relatively high in the waste rock while other sulfide-associated elements such as Cu, Pb and Zn were low compared to common sulfide-rich waste rock. Leaching of unsaturated waste rock lowered the pH, from around six down to two, resulting in continuously increasing element concentrations during the leaching period of 272 days. The concentrations of As (65 mg/L), Cu (6.9 mg/L), Sb (1.2 mg/L), Zn (149 mg/L) and S (43 g/L) were strongly elevated at the end of the leaching period. Different alkaline industrial residues such as slag, lime kiln dust and cement kiln dust were added as solid or as liquid to the waste rock in an attempt to inhibit sulfide oxidation through neo-formed phases on sulfide surfaces in order to decrease the mobility of metals and metalloids over longer time scale. This will result in a lower cost and efforts of measures after mine closure. Results from the experiments will be presented.

  4. Mechanochemical reduction of copper sulfide

    DEFF Research Database (Denmark)

    Balaz, P.; Takacs, L.; Jiang, Jianzhong

    2002-01-01

    The mechanochemical reduction of copper sulfide with iron was induced in a Fritsch P-6 planetary mill, using WC vial filled with argon and WC balls. Samples milled for specific intervals were analyzed by XRD and Mossbauer spectroscopy. Most of the reaction takes place during the first 10 min...... of milling and only FeS and Cu are found after 60 min. The main chemical process is accompanied by phase transformations of the sulfide phases as a result of milling. Djurleite partially transformed to chalcocite and a tetragonal copper sulfide phase before reduction. The cubic modification of FeS was formed...... first, transforming to hexagonal during the later stages of the process. The formation of off-stoichiometric phases and the release of some elemental sulfur by copper sulfide are also probable....

  5. Amperometric inhibitive biosensor based on horseradish peroxidase-nanoporous gold for sulfide determination

    Science.gov (United States)

    Sun, Huihui; Liu, Zhuang; Wu, Chao; Xu, Ping; Wang, Xia

    2016-08-01

    As a well-known toxic pollutant, sulfide is harmful to human health. In this study, a simple and sensitive amperometric inhibitive biosensor was developed for the determination of sulfide in the environment. By immobilizing nanoporous gold (NPG) on glassy carbon electrode (GCE), and encapsulating horseradish peroxidase (HRP) onto NPG, a HRP/NPG/GCE bioelectrode for sulfide detection was successfully constructed based on the inhibition of sulfide on HRP activity with o-Phenylenediamine (OPD) as a substrate. The resulted HRP/NPG/GCE bioelectrode achieved a wide linear range of 0.1–40 μM in sulfide detection with a high sensitivity of 1720 μA mM‑1 cm‑2 and a low detection limit of 0.027 μM. Additionally, the inhibition of sulfide on HRP is competitive inhibition with OPD as a substrate by Michaelis-Menten analysis. Notably, the recovery of HRP activity was quickly achieved by washing the HRP/NPG/GCE bioelectrode using differential pulse voltammetry (DPV) technique in deaerated PBS (50 mM, pH 7.0) for only 60 s. Furthermore, the real sample analysis of sulfide by the HRP/NPG/GCE bioelectrode was achieved. Based on above results, the HRP/NPG/GCE bioelectrode could be a better choice for the real determination of sulfide compared to inhibitive biosensors previously reported.

  6. A paradox resolved: Sulfide acquisition by roots of seep tubeworms sustains net chemoautotrophy

    Science.gov (United States)

    Freytag, John K.; Girguis, Peter R.; Bergquist, Derk C.; Andras, Jason P.; Childress, James J.; Fisher, Charles R.

    2001-01-01

    Vestimentiferan tubeworms, symbiotic with sulfur-oxidizing chemoautotrophic bacteria, dominate many cold-seep sites in the Gulf of Mexico. The most abundant vestimentiferan species at these sites, Lamellibrachia cf. luymesi, grows quite slowly to lengths exceeding 2 meters and lives in excess of 170–250 years. L. cf. luymesi can grow a posterior extension of its tube and tissue, termed a “root,” down into sulfidic sediments below its point of original attachment. This extension can be longer than the anterior portion of the animal. Here we show, using methods optimized for detection of hydrogen sulfide down to 0.1 μM in seawater, that hydrogen sulfide was never detected around the plumes of large cold-seep vestimentiferans and rarely detectable only around the bases of mature aggregations. Respiration experiments, which exposed the root portions of L. cf. luymesi to sulfide concentrations between 51–561 μM, demonstrate that L. cf. luymesi use their roots as a respiratory surface to acquire sulfide at an average rate of 4.1 μmol⋅g−1⋅h−1. Net dissolved inorganic carbon uptake across the plume of the tubeworms was shown to occur in response to exposure of the posterior (root) portion of the worms to sulfide, demonstrating that sulfide acquisition by roots of the seep vestimentiferan L. cf. luymesi can be sufficient to fuel net autotrophic total dissolved inorganic carbon uptake. PMID:11687647

  7. Arsenic mobilization from sulfidic materials from gold mines in Minas Gerais State

    Directory of Open Access Journals (Sweden)

    Renato Pereira de Andrade

    2008-01-01

    Full Text Available Acid drainage results from exposition of sulfides to the atmosphere. Arsenopyrite is a sulfide that releases arsenic (As to the environment when oxidized. This work evaluated the As mobility in six sulfidic geomaterials from gold mining areas in Minas Gerais State, Brazil. Grained samples (<2 mm were periodically leached with distilled water, during 70 days. Results suggested As sorption onto (hydroxides formed by oxidation of arsenopyrite. Low pH accelerated the acid generation, dissolving Fe oxihydroxides and releasing As. Presence of carbonates decreased oxidation rates and As release. On the other hand, lime added to a partially oxidized sample increased As mobilization.

  8. Hydrogen Sulfide and Polysulfides as Biological Mediators

    Directory of Open Access Journals (Sweden)

    Hideo Kimura

    2014-10-01

    Full Text Available Hydrogen sulfide (H2S is recognized as a biological mediator with various roles such as neuromodulation, regulation of the vascular tone, cytoprotection, anti-inflammation, oxygen sensing, angiogenesis, and generation of mitochondrial energy. It is produced by cystathionine β-synthase (CBS, cystathionine γ-lyase (CSE, and 3-mercaptopyruvate sulfurtransferase (3MST. The activity of CBS is enhanced by S-adenosyl methionine (SAM and glutathionylation, while it is inhibited by nitric oxide (NO and carbon monoxide (CO. The activity of CSE and cysteine aminotransferase (CAT, which produces the 3MST substrate 3-mercaptopyruvate (3MP, is regulated by Ca2+. H2S is oxidized to thiosulfate in mitochondria through the sequential action of sulfide quinone oxidoreductase (SQR, sulfur dioxygenase, and rhodanese. The rates of the production and clearance of H2S determine its cellular concentration. Polysulfides (H2Sn have been found to occur in the brain and activate transient receptor potential ankyrin 1 (TRPA1 channels, facilitate the translocation of nuclear factor erythroid 2-related factor 2 (Nrf2 to the nucleus, and suppress the activity of phosphatase and tensin homolog (PTEN by sulfurating (sulfhydrating the target cysteine residues. A cross talk between H2S and NO also plays an important role in cardioprotection as well as regulation of the vascular tone. H2S, polysulfides, and their cross talk with NO may mediate various physiological and pathophysiological responses.

  9. Hydrogen sulfide and polysulfides as biological mediators.

    Science.gov (United States)

    Kimura, Hideo

    2014-10-09

    Hydrogen sulfide (H2S) is recognized as a biological mediator with various roles such as neuromodulation, regulation of the vascular tone, cytoprotection, anti-inflammation, oxygen sensing, angiogenesis, and generation of mitochondrial energy. It is produced by cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3MST). The activity of CBS is enhanced by S-adenosyl methionine (SAM) and glutathionylation, while it is inhibited by nitric oxide (NO) and carbon monoxide (CO). The activity of CSE and cysteine aminotransferase (CAT), which produces the 3MST substrate 3-mercaptopyruvate (3MP), is regulated by Ca2+. H2S is oxidized to thiosulfate in mitochondria through the sequential action of sulfide quinone oxidoreductase (SQR), sulfur dioxygenase, and rhodanese. The rates of the production and clearance of H2S determine its cellular concentration. Polysulfides (H2Sn) have been found to occur in the brain and activate transient receptor potential ankyrin 1 (TRPA1) channels, facilitate the translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) to the nucleus, and suppress the activity of phosphatase and tensin homolog (PTEN) by sulfurating (sulfhydrating) the target cysteine residues. A cross talk between H2S and NO also plays an important role in cardioprotection as well as regulation of the vascular tone. H2S, polysulfides, and their cross talk with NO may mediate various physiological and pathophysiological responses.

  10. Sulfide Composition and Melt Stability Field in the Earth's Upper Mantle

    Science.gov (United States)

    Zhang, Z.; Hirschmann, M. M.

    2015-12-01

    In the Earth's upper mantle, sulfur occurs chiefly as (Fe, Ni)xS minerals and melts with near-monosulfide stoichiometries. These could have substantial influence on geochemical and geophysical properties of the Earth's interior. For example, sulfide mineral and melts are the major carriers of chalcophile and platinum group elements (PGEs) and sulfide melts are potentially responsible for mantle geophysical anomalies, as their physical properties (higher density, surface tension, electrical conductivity and lower melting points) differ greatly from those of silicates. Sulfide melts are a potential sink for reduced mantle carbon and perhaps be associated with carbon transport, including diamond precipitation. Sulfides may be molten in large parts of the mantle, but this is determined in part by sulfide composition, which is in turn a product of Fe-Ni exchange with olivine and of the effect of sulfur, oxygen, and carbon fugacities on metal/anion ratios of melts. Melting experiments define the monosulfide (Fe0.35Ni0.12Cu0.01S0.52) solidus from 1-8 GPa at carbon-free and graphite saturated conditions. The resulting carbon-free solidus is below the mantle adiabat to depths of at least 300 km, but does not indicate sulfide melting in continental lithosphere. In contrast, the graphite saturated solidus indicates melting in the lithosphere at 6-7 GPa (~200 km), close to the source conditions typical of diamond formation. To determine the composition of sulfide equilibrated with olivine, we performed experiments on monosulfide-olivine (crushed powders from San Carlos single crystal) under 2 GPa, 1400 ◦C. Our preliminary results suggests that Fe-Ni distribution coefficients KD, defined by (Ni/Fe)sulfide/(Ni/Fe)olivine, have significantly lower values than those determined previously at one atmosphere (Doyle and Naldrett 1987; Fleet and MacRae 1987; Gaetani and Grove 1997). This indicates that sulfide equilibrated with olivine in the mantle is richer in Fe than former

  11. Structure of 4-methylpyridinium Hydrogen Sulfide

    Science.gov (United States)

    Andras, Maria T.; Hepp, Aloysius F.; Fanwick, Phillip E.; Martuch, Robert A.; Duraj, Stan A.; Gordon, Edward M.

    1994-01-01

    4-Methylpyridinium hydrogen sulfide, (C6H7NH)HS, M(sub r) = 127.21, consists of C6H7NH(+) cations and HS(-) anions. Z = 2 for the crystal with monoclinic space group Cm (#8), dimensions of a = 8.679(2) A, b = 7.964(1) A, and c = 4.860(2) A, an angle beta of 101.10(2) degrees, and a volume of V = 329.6(3) A(exp 3). R = 0.039 and R(sub w) = 0.048 for 385 reflections with F(sub o)(exp 2) greater than 3 sigma(F(sub o)(exp 2)) and 59 variables. Both the C6H7NH(+) cation and the HS(-) anion lie on crystallographic mirror planes with the N,S, two carbon atoms, and two hydrogen atoms positioned in the planes. The hydrogen atom of the HS(-) anion was not located.

  12. Synthesis of furan from allenic sulfide derivatives

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this paper, we report the synthesis of furan derivatives from allenic sulfides. By the reaction with NaH, β-Hydroxyl allenic sulfides were found to generate furan products in excellent yields with the removal of phenylthio group. β-Aldehyde allenic sulfides were found to give similar furan products with one more substituent when treated with additional nucleophilic reagents. β-ketone allenic sulfides can also cyclize to give furan derivatives with the promotion of P2O5.

  13. Synthesis of furan from allenic sulfide derivatives

    Institute of Scientific and Technical Information of China (English)

    PENG LingLing; ZHANG Xiu; MA Jie; ZHONG ZhenZhen; ZHANG Zhe; ZHANG Yan; WANG JianBo

    2009-01-01

    In this paper, we report the synthesis of furan derivatives from allenic sulfides. By the reaction with NaH.,β-Hydroxyl allenic sulfides were found to generate furan products in excellent yields with the removal of phenylthio group.β-Aldehyde allenic sulfides were found to give similar furan products with one more substituent when treated with additional nucleophilic reagents. β-ketone allenic sulfides can also cyclize to give furan derivatives with the promotion of P2O5.

  14. 30 CFR 250.604 - Hydrogen sulfide.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Hydrogen sulfide. 250.604 Section 250.604... OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Well-Workover Operations § 250.604 Hydrogen sulfide. When a well-workover operation is conducted in zones known to contain hydrogen sulfide (H2S) or...

  15. 30 CFR 250.504 - Hydrogen sulfide.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Hydrogen sulfide. 250.504 Section 250.504... OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Well-Completion Operations § 250.504 Hydrogen sulfide. When a well-completion operation is conducted in zones known to contain hydrogen sulfide (H2S) or...

  16. 30 CFR 250.808 - Hydrogen sulfide.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Hydrogen sulfide. 250.808 Section 250.808... OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Production Safety Systems § 250.808 Hydrogen sulfide. Production operations in zones known to contain hydrogen sulfide (H2S) or in zones where the presence of...

  17. Influence of Gas Components on the Formation of Carbonyl Sulfide over Water-Gas Shift Catalyst B303Q

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Water-gas shift reaction catalyst at lower temperature (200-400 ℃) may improve the conversion of carbon monoxide. But carbonyl sulfide was found to be present over the sulfided cobaltmolybdenum/alumina catalyst for water-gas shift reaction. The influences of temperature, space velocity,and gas components on the formation of carbonyl sulfide over sulfided cobalt-molybdenum/alumina catalyst B303Q at 200-400 ℃ were studied in a tubular fixed-bed quartz-glass reactor under simulated water-gas shift conditions. The experimental results showed that the yield of carbonyl sulfide over B303Q catalyst reached a maximum at 220 ℃ with the increase in temperature, sharply decreased with the increase in space velocity and the content of water vapor, increased with the increase in the content of carbon monoxide and carbon dioxide, and its yield increased and then reached a stable value with the increase in the content of hydrogen and hydrogen sulfide. The formation mechanism of carbonyl sulfide over B303Q catalyst at 200-400 ℃ was discussed on the basis of how these factors influence the formation of COS. The yield of carbonyl sulfide over B303Q catalyst at 200-400 ℃ was the combined result of two reactions, that is, COS was first produced by the reaction of carbon monoxide with hydrogen sulfide,and then the as-produced COS was converted to hydrogen sulfide and carbon dioxide by hydrolysis. The mechanism of COS formation is assumed as follows: sulfur atoms in the Co9Ss-MoS2/Al2O3 crystal lattice were easily removed and formed carbonyl sulfide with CO, and then hydrogen sulfide in the water-gas shift gas reacted with the crystal lattice oxygen atoms in CoO-MoO3/Al2O3 to form Co9Ss-MoS2/Al2O3.This mechanism for the formation of COS over water-gas shift catalyst B303Q is in accordance with the Mars-Van Krevelen's redox mechanism over metal sulfide.

  18. Research on catalytic hydrolysis of carbonyl sulfide and carbon disulfide over ZrO2 modified activated carbon%氧化锆负载型活性炭催化水解COS和CS2

    Institute of Scientific and Technical Information of China (English)

    刘强; 柯明; 于沛; 胡海强; 宋昭峥

    2016-01-01

    以椰壳活性炭为载体,采用浸渍法制备ZrO2负载型活性炭催化剂,利用BET,XRD,XPS等手段对催化剂进行表征,考察了ZrO2负载量、焙烧温度、相对湿度、氧含量、反应温度、气态空速等因素对催化剂催化水解COS和CS2的影响。表征结果显示,反应后生成的硫和硫酸盐沉积在活性炭上,堵塞了活性炭的微孔,毒化了活性中心,从而使水解转化率下降。实验结果表明,w(ZrO2)=5.0%、焙烧温度500℃条件下制备的催化剂,在反应温度60℃、相对湿度19%、氧含量为1.0%(φ)、气态空速5000 h-1、COS质量浓度1.6 mg/L、CS2质量浓度0.1 mg/L时具有较高的同时水解COS和CS2的活性;COS和CS2同时水解转化率最高,100%转化率分别持续630 min和570 min。%A series of coconut shell-based active carbon catalysts loaded by ZrO2 were prepared by incipient-wetness impregnation method and characterized by BET,XRD,XPS. The effects of ZrO2 contents,calcinations temperatures,reaction temperature,O2 content,relative humidity and gas GHSV were also discussed respectively.The characterization results showed that the reaction products were sulfur and sulfate ion,which accumulated on the activated carbon’s surface and had negative effects on the catalyst by poisoning the active hydroxyl groups. The experimental results showed that catalysts with 5.0%(w) ZrO2 calcined at 500℃ had superior activity for the simultaneous catalytic hydrolysis of COS and CS2. The optimal purification properties reach at reaction temperature of 60℃, oxygen content of 1.0%(φ) and relative humidity of 19%,GHSV was 5 000 h-1,the concentration of COS and CS2 were 1.6 mg/L and 0.1 mg/L,100% COS conversion and CS2conversion are observed for about 630 min and 570 min respectively.

  19. Sulfide capacities of CaO-CaF2-CaCl2 melts

    Science.gov (United States)

    Simeonov, Simeon; Sakai, Toshihiko; Maeda, Masafumi

    1992-06-01

    The sulfide capacityC_{s^{2 - } } = ({text{pct S}}^{{text{2 - }}} )(p_{{text{O}}_{text{2}} } /p_{{text{S}}_{text{2}} } )^{1/2} ) of CaO-CaF2-CaCl2 slag was determined at temperatures from 1000 °C to 1300 °C by equilibrating molten slag, molten silver, and CO-CO2-Ar gas mixture. The sulfide capacity increases with replacing CaCl2 by CaF2 in slags of constant CaO contents. The sulfide capacity also increases with increasing temperature as well as with increasing CaO content at a constant ratio of CaF2/CaCl2 of unity. A linear relationship between the sulfide capacity and carbonate capacity in literature was observed on a logarithmic scale.

  20. The mechanism of the catalytic oxidation of hydrogen sulfide *1: III. An electron spin resonance study of the sulfur catalyzed oxidation of hydrogen sulfide

    NARCIS (Netherlands)

    Steijns, M.; Koopman, P.; Nieuwenhuijse, B.; Mars, P.

    1976-01-01

    ESR experiments on the oxidation of hydrogen sulfide were performed in the temperature range 20–150 °C. Alumina, active carbon and molecular sieve zeolite 13X were investigated as catalysts. For zeolite 13X it was demonstrated that the reaction is autocatalytic and that sulfur radicals are the activ

  1. Nanoscale Zero-Valent Iron for Sulfide Removal from Digested Piggery Wastewater

    Directory of Open Access Journals (Sweden)

    Sheng-Hsun Chaung

    2014-01-01

    Full Text Available The removal of dissolved sulfides in water and wastewater by nanoscale zero-valent iron (nZVI was examined in the study. Both laboratory batch studies and a pilot test in a 50,000-pig farm were conducted. Laboratory studies indicated that the sulfide removal with nZVI was a function of pH where an increase in pH decreased removal rates. The pH effect on the sulfide removal with nZVI is attributed to the formation of FeS through the precipitation of Fe(II and sulfide. The saturated adsorption capacities determined by the Langmuir model were 821.2, 486.3, and 359.7 mg/g at pH values 4, 7, and 12, respectively, for nZVI, largely higher than conventional adsorbents such as activated carbon and impregnated activated carbon. The surface characterization of sulfide-laden nZVI using XPS and TGA indicated the formation of iron sulfide, disulfide, and polysulfide that may account for the high adsorption capacity of nZVI towards sulfide. The pilot study showed the effectiveness of nZVI for sulfide removal; however, the adsorption capacity is almost 50 times less than that determined in the laboratory studies during the testing period of 30 d. The complexity of digested wastewater constituents may limit the effectiveness of nZVI. Microbial analysis suggested that the impact of nZVI on the change of microbial species distribution was relatively noticeable after the addition of nZVI.

  2. Selective Sulfidation of Lead Smelter Slag with Pyrite and Flotation Behavior of Synthetic ZnS

    Science.gov (United States)

    Han, Junwei; Liu, Wei; Wang, Dawei; Jiao, Fen; Zhang, Tianfu; Qin, Wenqing

    2016-08-01

    The selective sulfidation of lead smelter slag with pyrite in the presence of carbon and Na salts, and the flotation behavior of synthetic ZnS were studied. The effects of temperature, time, pyrite dosage, Na salts, and carbon additions were investigated based on thermodynamic calculation, and correspondingly, the growth mechanism of ZnS particles was studied at high temperatures. The results indicated that the zinc in lead smelter slag was selectively converted into zinc sulfides by sulfidation roasting. The sulfidation degree of zinc was increased until the temperature, time, pyrite, and carbon dosages reached their optimum values, under which it was more than 95 pct. The growth of ZnS particles largely depended upon roasting temperature, and the ZnS grains were significantly increased above 1373 K (1100 °C) due to the formation of a liquid phase. After the roasting, the zinc sulfides generated had a good floatability, and 88.34 pct of zinc was recovered by conventional flotation.

  3. Redox Biochemistry of Hydrogen Sulfide*

    OpenAIRE

    Kabil, Omer; Banerjee, Ruma

    2010-01-01

    H2S, the most recently discovered gasotransmitter, might in fact be the evolutionary matriarch of this family, being both ancient and highly reduced. Disruption of γ-cystathionase in mice leads to cardiovascular dysfunction and marked hypertension, suggesting a key role for this enzyme in H2S production in the vasculature. However, patients with inherited deficiency in γ-cystathionase apparently do not present vascular pathology. A mitochondrial pathway disposes sulfide and couples it to oxid...

  4. Sulfide intrusion and detoxification in seagrasses ecosystems

    DEFF Research Database (Denmark)

    Hasler-Sheetal, Harald; Holmer, Marianne

    Sulfide intrusion in seagrasses represents a global threat to seagrasses and thereby an important parameter in resilience of seagrass ecosystems. In contrast seegrasses colonize and grow in hostile sediments, where they are constantly exposed to invasion of toxic gaseous sulfide. Remarkably little...... strategies of seagrasses to sustain sulfide intrusion. Using stable isotope tracing, scanning electron microscopy with x-ray analysis, tracing sulfur compounds combined with ecosystem parameters we found different spatial, intraspecific and interspecific strategies to cope with sulfidic sediments. 1...... not present in terrestrial plants at that level. Sulfide is not necessarily toxic but used as sulfur nutrition, presupposing healthy seagrass ecosystems that can support detoxification mechanisms. Presence or absence of those mechanisms determines susceptibility of seagrass ecosystems to sediment sulfide...

  5. Simultaneous removal of sulfide, nitrate and acetate under denitrifying sulfide removal condition: Modeling and experimental validation

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Xijun; Chen, Chuan; Wang, Aijie; Guo, Wanqian; Zhou, Xu [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090 (China); Lee, Duu-Jong, E-mail: djlee@ntu.edu.tw [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090 (China); Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan (China); Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Ren, Nanqi, E-mail: rnq@hit.edu.cn [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090 (China); Chang, Jo-Shu [Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan, Taiwan (China)

    2014-01-15

    Graphical abstract: Model evaluation applied to case study 1: (A-G) S{sup 2−}, NO{sub 3}{sup −}-N, NO{sub 2}{sup −}-N, and Ac{sup −}-C profiles under initial sulfide concentrations of 156.2 (A), 539 (B), 964 (C), 1490 (D), 342.7 (E), 718 (F), and 1140.7 (G) mg L{sup −1}. The solid line represents simulated result and scatter represents experimental result. -- Highlights: • This work developed a mathematical model for DSR process. • Kinetics of sulfur–nitrogen–carbon and interactions between denitrifiers were studied. • Kinetic parameters of the model were estimated via data fitting. • The model described kinetic behaviors of DSR processes over wide parametric range. -- Abstract: Simultaneous removal of sulfide (S{sup 2−}), nitrate (NO{sub 3}{sup −}) and acetate (Ac{sup −}) under denitrifying sulfide removal process (DSR) is a novel biological wastewater treatment process. This work developed a mathematical model to describe the kinetic behavior of sulfur–nitrogen–carbon and interactions between autotrophic denitrifiers and heterotrophic denitrifiers. The kinetic parameters of the model were estimated via data fitting considering the effects of initial S{sup 2−} concentration, S{sup 2−}/NO{sub 3}{sup −}-N ratio and Ac{sup −}-C/NO{sub 3}{sup −}-N ratio. Simulation supported that the heterotrophic denitratation step (NO{sub 3}{sup −} reduction to NO{sub 2}{sup −}) was inhibited by S{sup 2−} compared with the denitritation step (NO{sub 2}{sup −} reduction to N{sub 2}). Also, the S{sup 2−} oxidation by autotrophic denitrifiers was shown two times lower in rate with NO{sub 2}{sup −} as electron acceptor than that with NO{sub 3}{sup −} as electron acceptor. NO{sub 3}{sup −} reduction by autotrophic denitrifiers occurs 3–10 times slower when S{sup 0} participates as final electron donor compared to the S{sup 2−}-driven pathway. Model simulation on continuous-flow DSR reactor suggested that the adjustment of

  6. Giant hydrogen sulfide plume in the oxygen minimum zone off Peru supports chemolithoautotrophy.

    Directory of Open Access Journals (Sweden)

    Harald Schunck

    Full Text Available In Eastern Boundary Upwelling Systems nutrient-rich waters are transported to the ocean surface, fuelling high photoautotrophic primary production. Subsequent heterotrophic decomposition of the produced biomass increases the oxygen-depletion at intermediate water depths, which can result in the formation of oxygen minimum zones (OMZ. OMZs can sporadically accumulate hydrogen sulfide (H2S, which is toxic to most multicellular organisms and has been implicated in massive fish kills. During a cruise to the OMZ off Peru in January 2009 we found a sulfidic plume in continental shelf waters, covering an area >5500 km(2, which contained ∼2.2×10(4 tons of H2S. This was the first time that H2S was measured in the Peruvian OMZ and with ∼440 km(3 the largest plume ever reported for oceanic waters. We assessed the phylogenetic and functional diversity of the inhabiting microbial community by high-throughput sequencing of DNA and RNA, while its metabolic activity was determined with rate measurements of carbon fixation and nitrogen transformation processes. The waters were dominated by several distinct γ-, δ- and ε-proteobacterial taxa associated with either sulfur oxidation or sulfate reduction. Our results suggest that these chemolithoautotrophic bacteria utilized several oxidants (oxygen, nitrate, nitrite, nitric oxide and nitrous oxide to detoxify the sulfidic waters well below the oxic surface. The chemolithoautotrophic activity at our sampling site led to high rates of dark carbon fixation. Assuming that these chemolithoautotrophic rates were maintained throughout the sulfidic waters, they could be representing as much as ∼30% of the photoautotrophic carbon fixation. Postulated changes such as eutrophication and global warming, which lead to an expansion and intensification of OMZs, might also increase the frequency of sulfidic waters. We suggest that the chemolithoautotrophically fixed carbon may be involved in a negative feedback loop that

  7. Investigation of Hydrogen Sulfide Gas as a Treatment against P. falciparum, Murine Cerebral Malaria, and the Importance of Thiolation State in the Development of Cerebral Malaria

    DEFF Research Database (Denmark)

    Dellavalle, Brian; Staalsoe, Trine; Kurtzhals, Jørgen Anders;

    2013-01-01

    Cerebral malaria (CM) is a potentially fatal cerebrovascular disease of complex pathogenesis caused by Plasmodium falciparum. Hydrogen sulfide (HS) is a physiological gas, similar to nitric oxide and carbon monoxide, involved in cellular metabolism, vascular tension, inflammation, and cell death...

  8. Ab Initio Investigation of Methanthiol and Dimethyl Sulfide Adsorption on Zeolite

    Institute of Scientific and Technical Information of China (English)

    Lü Renqing

    2006-01-01

    The Hartree-Fock and cluster model methods have been employed to investigate interactions of methanthiol or dimethyl sulfide on zeolites. Molecular complexes formed by adsorption of methanthiol on silanol H3SiOSi(OH)2OSiH3 with five coordination forms and dimethyl sulfide on silanol H3SiOSi(OH)2OSiH3 with four coordination forms, and Br(o)nsted acid sites of bridging hydroxyl H3Si(OH)Al(OH)2OSiH3 entering into interactions with methanthiol or dimethyl sulfide have been investigated. Full optimization and frequency analysis of all cluster models have been carried out using the Hartree-Fock method at 6-31 +G** basis set level for hydrogen, silicon, aluminum, oxygen, carbon, and sulfur atoms. The structures and energy changes of different coordination forms derived from methanthiol and H3Si(OH)Al(OH)2OSiH3, dimethyl sulfide and H3Si(OH)Al(OH)2OSiH3, methanthiol and H3SiOSi(OH)2OSiH3, dimethyl sulfide and H3SiOSi(OH)2OSiH3 complexes have been comparatively studied. The calculated results showed that the nature of interactions leading to the formation of the bridging hydroxyl-methanthiol, silanol-methanthiol,bridging hydroxyl-dimethyl sulfide, silanol-dimethyl sulfide complexes was governed by the Van der Waals force as confirmed by a small change in geometric structures and properties. Methanthiol and dimethyl sulfide molecules were adsorbed on bridging hydroxyl group prior to silanol group as evidenced by the heat of adsorption, and the protonization of methanthiol adsorption on bridging hydroxyl model, which was supposed in the literature, was not found.

  9. Ways to improve the removal of hydrogen sulfide from coke-oven gas

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, M.D.; Lyannaya; No. 1, Z.G.; Ignatova, E.P.; Zbykovskii, I.I.; Shukh, Ya.I.; Andreiko, I.M.; Garkushenko, I.Ya.

    1979-01-01

    Our calculations showed that, if the gas temperatures ahead of the scrubbers were reuced to 30/sup 0/C and 300 to 400 liters/h of concentrated ammonia water were added to the circuit, the degree of hydrogen sulfide absorption could be brought to 58 to 65%, i.e., the hydrogen sulfide content in the return gas would be less than 2.5 g/m/sup 3/. All the hydrogen sulfide removed from the gas would enter the concentrated ammonia water, which would be delivered to facilities for production of soda by the ammonia method. The ammonium sulfide formed in the liquor would be a desirable component, acting to inhibit corrosion. This would provide the simplest solution to the problem of utilizing the hydrogen sulfide removed from the gas. Our investigation thus showed that the hydrogen sulfide content of the coke-oven gas can be reduced to a permissible level in the department as it now exists, without substantial remodelling of the scrubber department. Implementation of the proposed measures (installation of an additional gas cooler beyond the blower and introduction of 300 to 400 liters/h of 20% ammonia liquor into the circuit) will make it possible to improve air-pollution conditions in the carbonization department and adjoining areas, reduce the corrosion of the gaslines, utilize that portion of the gas now discharged into the atmosphere, and eliminate the need for construction of an expensive special facility for removal of hydrogen sulfide. Addition of concentrated ammonia liquor into the scrubber-liquor circuit in the amounts indicated above raised the degree of hydrogen sulfide absorption from 31 to 43 to 47%.

  10. Mechanism of heterogeneous reaction of carbonyl sulfide on magnesium oxide.

    Science.gov (United States)

    Liu, Yongchun; He, Hong; Xu, Wenqing; Yu, Yunbo

    2007-05-24

    Heterogeneous reaction of carbonyl sulfide (OCS) on magnesium oxide (MgO) under ambient conditions was investigated by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), quadrupole mass spectrometer (QMS), and density functional theory (DFT) calculations. It reveals that OCS can be catalytically hydrolyzed by surface hydroxyl on MgO to produce carbon dioxide (CO2) and hydrogen sulfide (H2S), and then H2S can be further catalytically oxidized by surface oxygen or gaseous oxygen on MgO to form sulfite (SO3(2-)) and sulfate (SO4(2-)). Hydrogen thiocarbonate (HSCO2-) was found to be the crucial intermediate. Surface hydrogen sulfide (HS), sulfur dioxide (SO2), and surface sulfite (SO3(2-)) were also found to be intermediates for the formation of sulfate. Furthermore, the surface hydroxyl contributes not only to the formation of HSCO2- but also to HSCO2- decomposition. On the basis of experimental results, the heterogeneous reaction mechanism of OCS on MgO was discussed.

  11. Adsorption of dimethyl sulfide from aqueous solution by a cost-effective bamboo charcoal.

    Science.gov (United States)

    Wang, Ming; Huang, Zheng-Hong; Liu, Guangjia; Kang, Feiyu

    2011-06-15

    The adsorption of dimethyl sulfide from an aqueous solution by a cost-effective bamboo charcoal from Dendrocalamus was studied in comparison with other carbon adsorbents. The bamboo charcoal exhibited superior adsorption on dimethyl sulfide compared with powdered activated carbons at different adsorbent dosages. The adsorption characteristics of dimethyl sulfide onto bamboo charcoal were investigated under varying experimental conditions such as particle size, contact time, initial concentration and adsorbent dosage. The dimethyl sulfide removal was enhanced from 31 to 63% as the particle size was decreased from 24-40 to >300 mesh for the bamboo charcoal. The removal efficiency increased with increasing the adsorbent dosage from 0.5 to 10mg, and reached 70% removal efficiency at 10mg adsorbed. The adsorption capacity (μg/g) increased with increasing concentration of dimethyl sulfide while the removal efficiency decreased. The adsorption process conforms well to a pseudo-second-order kinetics model. The adsorption of dimethyl sulfide is more appropriately described by the Freundlich isotherm (R(2), 0.9926) than by the Langmuir isotherm (R(2), 0.8685). Bamboo charcoal was characterized by various analytical methods to understand the adsorption mechanism. Bamboo charcoal is abundant in acidic and alcohol functional groups normally not observed in PAC. A distinct difference is that the superior mineral composition of Fe (0.4 wt%) and Mn (0.6 wt%) was detected in bamboo charcoal-elements not found in PAC. Acidic functional group and specific adsorption sites would be responsible for the strong adsorption of dimethyl sulfide onto bamboo charcoal of Dendrocalamus origin.

  12. Hydrogen sulfide in renal physiology, disease and transplantation - The smell of renal protection

    NARCIS (Netherlands)

    Koning, Anne M.; Frenay, Anne-Roos S.; Leuvenink, Henri G. D.; van Goor, Harry

    2015-01-01

    Hydrogen sulfide (H2S), the third gasotransmitter, next to nitric oxide and carbon monoxide, is a key mediator in physiology and disease. It is involved in homeostatic functions, such as blood pressure control, electrolyte balance and apoptosis, and regulates pathological mechanisms, including oxida

  13. Ammonia, total reduced sulfides, and greenhouse gases of pine chip and corn stover bedding packs

    Science.gov (United States)

    Bedding materials may affect air quality in livestock facilities. The objective of this study was to compare headspace concentrations of ammonia (NH3), total reduced sulfides (TRS), carbon dioxide (CO2),methane (CH4), and nitrous oxide (N2O) when pine wood chips and corn stover were mixed in various...

  14. Hydrogen sulfide and vascular relaxation

    Institute of Scientific and Technical Information of China (English)

    SUN Yan; TANG Chao-shu; DU Jun-bao; JIN Hong-fang

    2011-01-01

    Objective To review the vasorelaxant effects of hydrogen sulfide (H2S) in arterial rings in the cardiovascular system under both physiological and pathophysiological conditions and the possible mechanisms involved.Data sources The data in this review were obtained from Medline and Pubmed sources from 1997 to 2011 using the search terms "hydrogen sulfide" and ""vascular relaxation".Study selection Articles describing the role of hydrogen sulfide in the regulation of vascular activity and its vasorelaxant effects were selected.Results H2S plays an important role in the regulation of cardiovascular tone.The vasomodulatory effects of H2S depend on factors including concentration,species and tissue type.The H2S donor,sodium hydrosulfide (NarS),causes vasorelaxation of rat isolated aortic rings in a dose-dependent manner.This effect was more pronounced than that observed in pulmonary arterial rings.The expression of KATP channel proteins and mRNA in the aortic rings was increased compared with pulmonary artery rings.H2S is involved in the pathogenesis of a variety of cardiovascular diseases.Downregulation of the endogenous H2S pathway is an important factor in the pathogenesis of cardiovascular diseases.The vasorelaxant effects of H2S have been shown to be mediated by activation of KATP channels in vascular smooth muscle cells and via the induction of acidification due to activation of the CI/HCO3 exchanger.It is speculated that the mechanisms underlying the vasoconstrictive function of H2S in the aortic rings involves decreased NO production and inhibition of cAMP accumulation.Conclusion H2S is an important endogenous gasotransmitter in the cardiovascular system and acts as a modulator of vascular tone in the homeostatic regulation of blood pressure.

  15. Medical Functions of Hydrogen Sulfide.

    Science.gov (United States)

    Olas, Beata

    2016-01-01

    Hydrogen sulfide (H(2)S) is a gasomediator synthesized from L- and D-cysteine in various tissues. It is involved in a number of physiological and pathological processes. H(2)S exhibits antiatherosclerotic, vasodilator, and proangiogenic properties, and protects the kidney and heart from damage following ischemia/reperfusion injury. H(2)S donors may be natural or synthetic, and may be used for the safe treatment of a wide range of diseases. This review article summarizes the current state of knowledge of the therapeutic function of H(2)S.

  16. Ammonia and hydrogen sulfide removal using biochar

    Science.gov (United States)

    Reducing ammonia and hydrogen sulfide emissions from livestock facilities is an important issue for many communities and livestock producers. Ammonia has been regarded as odorous, precursor for particulate matter (PM), and contributed to livestock mortality. Hydrogen sulfide is highly toxic at elev...

  17. Sulfide toxicity kinetics of a uasb reactor

    Directory of Open Access Journals (Sweden)

    D. R. Paula Jr.

    2009-12-01

    Full Text Available The effect of sulfide toxicity on kinetic parameters of anaerobic organic matter removal in a UASB (up-flow anaerobic sludge blanket reactor is presented. Two lab-scale UASB reactors (10.5 L were operated continuously during 12 months. The reactors were fed with synthetic wastes prepared daily using glucose, ammonium acetate, methanol and nutrient solution. One of the reactors also received increasing concentrations of sodium sulfide. For both reactors, the flow rate of 16 L.d-1 was held constant throughout the experiment, corresponding to a hydraulic retention time of 15.6 hours. The classic model for non-competitive sulfide inhibition was applied to the experimental data for determining the overall kinetic parameter of specific substrate utilization (q and the sulfide inhibition coefficient (Ki. The application of the kinetic parameters determined allows prediction of methanogenesis inhibition and thus the adoption of operating parameters to minimize sulfide toxicity in UASB reactors.

  18. Chirped laser dispersion spectroscopy for laser-based hydrogen sulfide detection in open-path conditions.

    Science.gov (United States)

    Nikodem, Michał

    2016-05-16

    In this paper the design and characterization of a near-IR Chirped Laser Dispersion Spectroscopy (CLaDS)-based setup for hydrogen sulfide (H2S) detection is reported. This system can be implemented for open-path sensing also in standoff configuration. Target transition selection, system noise and detection limit are discussed and characterized. Furthermore, the cross-interference with other molecules is analyzed. CLaDS-based detection is shown to be highly immune to background carbon dioxide changes, which is a critical issue in accurate open-path sensing of hydrogen sulfide.

  19. Plasma-chemical treatment of hydrogen sulfide in natural gas processing. Final report, May 1991--December 1992

    Energy Technology Data Exchange (ETDEWEB)

    Harkness, J.B.L.; Doctor, R.D. [Argonne National Lab., IL (United States)

    1993-05-01

    A new process for the treatment of hydrogen sulfide waste that uses microwave plasma-chemical technology has been under development in Russia and the United States. Whereas the present waste-treatment technology, at best, only recovers sulfur, this novel process recovers both hydrogen and sulfur by dissociating hydrogen sulfide in a plasma by means of a microwave or radio-frequency reactor. A research project has been undertaken to determine the suitability of the plasma process in natural gas processing applications. The experiments tested acid-gas compositions with 30--65% carbon dioxide, 0--7% water, and 0--0.2% of a standard mixture of pipeline gas. The balance gas in all cases was hydrogen sulfide. The reactor pressure for the experiments was 50 torr, and the microwave power was 1.0 kW. Conversions of hydrogen sulfide ranged from 80 to 100%, while 35--50% of the carbon dioxide was converted to carbon monoxide. This conversion of carbon dioxide resulted in a loss of hydrogen production and an energy loss from a hydrogen sulfide waste-treatment perspective. Tests of a direct natural gas treatment concept showed that hydrocarbon losses were unacceptably high; consequently, the concept would not be economically viable.

  20. Sulfide capacity of CaO-CaF2-SiO2 slags

    Science.gov (United States)

    Susaki, Katsujiro; Maeda, Masafumi; Sano, Nobuo

    1990-02-01

    The sulfide capacity C S 2- = (pct S2-) · ( P O 2/ P S 2)1/2) of CaO-CaF2-SiO2 slags saturated with CaO, 3CaO · SiO2 or 2CaOSiO2 was determined at 1200 °C, 1250 °C, 1300 °C, and 1350 °C by equilibrating molten slag, molten silver, and CO-CO2 gas mixtures. Higher sulfide capacities were obtained for CaO-saturated slags. A drastic decrease was observed in those values when the ratio pct CaO/pct SiO2 is less than 2. The sulfur partition between carbon-saturated iron melts and presently investigated slags was calculated by using the sulfide capacities obtained and the activity coefficient of sulfur in carbon-saturated iron, which was also experimentally determined. For slags saturated with CaO, partitions of sulfur as high as 10,000 were obtained at 1300 °C and 1350 °C. Correlations between the sulfide capacity and other basicity indexes such as carbonate capacity and theoretical optical basicity were also discussed.

  1. Sulfide oxidation as a process for the formation of copper-rich magmatic sulfides

    Science.gov (United States)

    Wohlgemuth-Ueberwasser, Cora C.; Fonseca, Raúl O. C.; Ballhaus, Chris; Berndt, Jasper

    2013-01-01

    Typical magmatic sulfides are dominated by pyrrhotite and pentlandite with minor chalcopyrite, and the bulk atomic Cu/Fe ratio of these sulfides is typically less than unity. However, there are rare magmatic sulfide occurrences that are dominated by Cu-rich sulfides (e.g., bornite, digenite, and chalcopyrite, sometimes coexisting with metallic Cu) with atomic Cu/Fe as high as 5. Typically, these types of sulfide assemblages occur in the upper parts of moderately to highly fractionated layered mafic-ultramafic intrusions, a well-known example being the Pd/Au reef in the Upper Middle Zone of the Skaergaard intrusion. Processes proposed to explain why these sulfides are so unusually rich in Cu include fractional crystallization of Fe/(Ni) monosulfide and infiltration of postmagmatic Cu-rich fluids. In this contribution, we explore and experimentally evaluate a third possibility: that Cu-rich magmatic sulfides may be the result of magmatic oxidation. FeS-dominated Ni/Cu-bearing sulfides were equilibrated at variable oxygen fugacities in both open and closed system. Our results show that the Cu/Fe ratio of the sulfide melt increases as a function of oxygen fugacity due to the preferential conversion of FeS into FeO and FeO1.5, and the resistance of Cu2S to being converted into an oxide component even at oxygen fugacities characteristic of the sulfide/sulfate transition (above FMQ + 1). This phenomenon will lead to an increase in the metal/S ratio of a sulfide liquid and will also depress its liquidus temperature. As such, any modeling of the sulfide liquid line of descent in magmatic sulfide complexes needs to address this issue.

  2. 21 CFR 177.2490 - Polyphenylene sulfide resins.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polyphenylene sulfide resins. 177.2490 Section 177... Components of Articles Intended for Repeated Use § 177.2490 Polyphenylene sulfide resins. Polyphenylene sulfide resins (poly(1,4-phenylene sulfide) resins) may be safely used as coatings or components...

  3. Toxicity of sulfide to early life-stages of wild rice (Zizania palustris).

    Science.gov (United States)

    Fort, Douglas J; Todhunter, Kevin; Fort, Troy D; Mathis, Michael B; Walker, Rachel; Hansel, Mike; Hall, Scott; Richards, Robin; Anderson, Kurt

    2017-02-07

    Wild rice (Zizania palustris) sensitivity to sulfide is not well understood. Since sulfate in surface waters is reduced to sulfide by anaerobic bacteria in sediments and historical information indicated that 10 mg/L sulfate in Minnesota surface water reduced Z. palustris abundance, the Minnesota Pollution Control Agency (MPCA) established 10 mg/L sulfate as a water quality criterion in 1973. A 21-day daily-renewal hydroponic study was conducted to evaluate sulfide toxicity to wild rice and the potential mitigation of sulfide toxicity by Fe. The hydroponic design used hypoxic test media for seed and root exposure and aerobic headspace for the vegetative portion of the plant. Test concentrations were 0.3, 1.6, 3.1, 7.8, and 12.5 mg/L sulfide in test media with 0.8, 2.8, and 10.8 mg/L total Fe used to evaluate the impact of iron on sulfide toxicity. Visual assessments (i.e., no plants harvested) of seed activation, mesocotyl emergence, seedling survival, and phytoxicity were conducted 10 days following dark-phase exposure. Each treatment was also evaluated for time to 30% emergence (ET30), total plant biomass, root and shoot lengths, and signs of phytotoxicity at study conclusion (21 days). Results from this study indicated that exposure of developing wild rice to sulfide at ≥3.1 mg sulfide/L in the presence of 0.8 mg/L iron reduced mesocotyl emergence. Sulfide toxicity was mitigated by the addition of iron at 2.8 and 10.8 mg /L relative to the control value of 0.8 mg Fe/L, demonstrating the importance of iron in mitigating sulfide toxicity to wild rice. Ultimately, determination of site-specific sulfate criteria that consider factors that alter toxicity, including sediment Fe and organic carbon, are necessary. This article is protected by copyright. All rights reserved.

  4. [Biooxidation of a Double-Refractory Gold-Bearing Sulfide Ore Concentrate].

    Science.gov (United States)

    Bulaev, A G; Kanaeva, Z K; Kanaev, A T; Kondrat'eva, T F

    2015-01-01

    The efficiency of biooxidation for treatment of a double-refractory gold-bearing sulfide ore concentrate from the Bakyrchik deposit (East Kazakhstan) was defined. The experiments were conducted in two different modes, i.e., with the standard liquid medium and the medium imitating the chemical composition of the Bakyrchik deposit groundwater and containing high concentrations of sodium, magnesium, and chloride. The concentrate contained 17.5% of organic carbon, 6% of pyrite and 13% arsenopyrite. Gold content was 57.5 g t@-1@. Direct gold recovery by cyanidation was very low (2.8%). While biooxidation was efficient in both cases (approximately 90% of sulfide sulfur was oxidized), the efficiency of cyanidation was low (39 and 32%, respectively). This fact suggests high efficiency of biooxidation is insufficient for efficient treatment of double-refractory gold-bearing sulfide ore concentrates.

  5. Pyrrhotite mineralization as a search criterion for sulfide deposits at sediment-covered spreading centers

    Science.gov (United States)

    Bogdanova, O. Yu.; Lein, A. Yu.; Dara, O. M.; Ozhogina, E. G.; Lisitzin, A. P.

    2016-09-01

    Pyrrhotite ores forming the hydrothermal vents of the Hydrothermal Hills in the Southern Trough of the Guaymas depression were studied. A series of features pointing to the occurrence of surface and buried sulfide deposits of pyrrhotite mineralization was revealed: the presence of pyrrhotite associations to hydrocarbons of oil series; low concentrations of Cu, Zn, and Pb; the enrichment of sulfur of pyrrhotite and hydrogen sulfide of hydrothermal solutions in heavy 34S isotope by 5-7%; and the heavy isotope composition of carbon in naphthoid compounds. The results obtained allow one to suggest searching for large sulfide deposits at active rifts of high spreading and sedimentation rates, i.e., at near-continental rifts of the humid zone of avalanche sedimentation.

  6. Electrochemical Study on Corrosion Behavior of Oil Pipeline Steels in Carbon and Hydrogen Sulfide Solution%石油管线钢在H2S/CO2环境中腐蚀行为的电化学研究

    Institute of Scientific and Technical Information of China (English)

    王丹; 吴明; 陈旭; 谢飞; 李睿; 徐鹏惠

    2011-01-01

    The corrosion behavior of 15# steels in carbon and hydrogen sulfide solution was studied by the polarization curves and EIS. The result shows that the corrosion rate of 15# steel in NaCI solution has accelerated, when joined H2S and CO2 , moreover, from the NaCI solution, NaCI - CO2 solution to the NaCI - CO2 - H2S solution, then to NaCI - H2S solution , the electrochemical reaction process of resistance is getting smaller, the corrosion current density is bigger and the corrosive rate is faster.%采用极化曲线法和交流阻抗法研究了15#钢在H2S/CO2环境下的电化学行为.试验结果表明,H2S和CO2的存在加速了15#钢在NaCl溶液中的腐蚀速率,管线钢在NaCl溶液、NaCl-CO2溶液、NaCl-CO2-H2S溶液以及NaCl-H2S溶液中电化学反应过程所受的阻力愈来愈小,腐蚀电流密度越来越大,腐蚀速率越来越快.

  7. Density Functional Investigation of Methanethiol and Dimethyl Sulfide Adsorption on Zeolite

    Institute of Scientific and Technical Information of China (English)

    Renqing Lü; Guangmin Qiu; Chenguang Liu

    2006-01-01

    The density functional theory and cluster model methods have been employed to investigate the interactions between methanethiol, dimethyl sulfide and zeolites. The molecular complexes formed by adsorption of methanethiol or dimethyl sulfide on silanol H3SiOSi(OH)2OSiH3 with five coordination forms or four coordination forms, and complexes formed by interactions of Br(o)nsted acid sites of bridging hydroxyl H3Si(OH)Al(OH)2OSiH3 with methanethiol or dimethyl sulfide have been investigated. Full optimization and frequency analysis of all cluster models have been carried out using the B3LYP hybrid method at 6-31+G (d,p) basis set level for hydrogen, silicon, aluminum, oxygen,carbon, and sulfur atoms. The structures and energy changes of different coordination forms between methanethiol and H3Si(OH)Al(OH)2OSiH3, dimethyl sulfide and H3Si(OH)Al(OH)2OSiH3, methanethiol and H3SiOSi(OH)2OSiH3, dimethyl sulfide and H3SiOSi(OH)2OSiH3 complexes have been comparatively studied. The calculated results showed the nature of interactions that led to the formation of all complexes was van der Waals force confirmed by an insignificant change of geometric structures and properties. The conclusions that methanethiol and dimethyl sulfide molecules were adsorbed on bridging hydroxyl group prior to silanol group were obtained on the basis of adsorption heat, the most stable adsorption models of a 6 ring structure for interaction between bridging hydroxyl and methanethiol, and a 7 ring structure for interaction between bridging hydroxyl and dimethyl sulfide.

  8. Influences of species of metals and supports on the hydrogenation activity of carbon-supported metal sulfides catalysts; Tanso biryushi tanji shokubai no suisoka kassei ni taisuru kassei kinzoku oyobi tantaishu no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Sakanishi, K.; Hasuo, H.; Taniguchi, H.; Nagamatsu, T.; Mochida, I. [Kyushu University, Fukuoka (Japan). Institute of Advanced Material Study

    1996-10-28

    In order to design catalysts suitable for primary liquefaction stage and secondary upgrading stage respectively in the multi-stage liquefaction process, various carbon-supported catalysts were prepared. Catalytic activities of them were investigated for the hydrogenation of 1-methylnaphthalene, to discuss the influences of metals and carbon species on the catalytic activity. Various water soluble and oil soluble Mo and Ni salts were used for NiMo supported catalysts. Among various carbon supports, Ketjen Black (KB) was effective for preparing the catalyst showing the most excellent hydrogenation activity. The KB and Black Pearl 2000 (BP2000) showing high hydrogenation activity were fine particles having high specific surface area more than 1000 m{sup 2}/g and primary particle diameter around 30 nm. This was inferred to contribute to the high dispersion support of active metals. Since such fine particles of carbon exhibited hydrophobic surface, they were suitable for preparing catalysts from the methanol-soluble metals. Although Ni and Mo added iron-based catalysts provided lower aromatic hydrogenation activity, they exhibited liquefaction activity competing with the NiMo/KB catalyst. 3 refs., 1 fig., 3 tabs.

  9. Efficient new process for the desulfurization of mixtures of air and hydrogen sulfide via a dielectric barrier discharge plasma

    Directory of Open Access Journals (Sweden)

    S. Dahle

    2015-10-01

    Full Text Available The efficient removal of hydrogen sulfide, H2S, from streams of H2S in air via a dielectric barrier discharge (DBD plasma has been investigated using a quadrupole mass spectrometer. A suitable plasma device with a reservoir for storing sorbent powder of various kinds within the plasma region was constructed. Plasma treatments of gas streams with high concentrations of hydrogen sulfide in air yielded a removal of more than 98% of the initial hydrogen sulfide and a deposition of sulfur at the surface of the dielectric, while small amounts of sulfur dioxide were generated. The presence of calcium carbonate within the plasma region of the DBD device resulted in the removal of over 99% of the initial hydrogen sulfide content and the removal of 98% of the initial sulfur dioxide impurities from the gas mixture.

  10. Redox biochemistry of hydrogen sulfide.

    Science.gov (United States)

    Kabil, Omer; Banerjee, Ruma

    2010-07-16

    H(2)S, the most recently discovered gasotransmitter, might in fact be the evolutionary matriarch of this family, being both ancient and highly reduced. Disruption of gamma-cystathionase in mice leads to cardiovascular dysfunction and marked hypertension, suggesting a key role for this enzyme in H(2)S production in the vasculature. However, patients with inherited deficiency in gamma-cystathionase apparently do not present vascular pathology. A mitochondrial pathway disposes sulfide and couples it to oxidative phosphorylation while also exposing cytochrome c oxidase to this metabolic poison. This report focuses on the biochemistry of H(2)S biogenesis and clearance, on the molecular mechanisms of its action, and on its varied biological effects.

  11. Microbial control of hydrogen sulfide production

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, A.D.; Bhupathiraju, V.K.; Wofford, N.; McInerney, M.J. [Univ. of Oklahoma, Tulsa, OK (United States)] [and others

    1995-12-31

    A sulfide-resistant strain of Thiobacillus denitrificans, strain F, prevented the accumulation of sulfide by Desulfovibrio desulfuricans when both organisms were grown in liquid medium. The wild-type strain of T. denitrificans did not prevent the accumulation of sulfide produced by D. desulfuricans. Strain F also prevented the accumulation of sulfide by a mixed population of sulfate-reducing bacteria enriched from an oil field brine. Fermentation balances showed that strain F stoichiometrically oxidized the sulfide produced by D. desulfuricans and the oil field brine enrichment to sulfate. The ability of a strain F to control sulfide production in an experimental system of cores and formation water from the Redfield, Iowa, natural gas storage facility was also investigated. A stable, sulfide-producing biofilm was established in two separate core systems, one of which was inoculated with strain F while the other core system (control) was treated in an identical manner, but was not inoculated with strain F. When formation water with 10 mM acetate and 5 mM nitrate was injected into both core systems, the effluent sulfide concentrations in the control core system ranged from 200 to 460 {mu}M. In the test core system inoculated with strain F, the effluent sulfide concentrations were lower, ranging from 70 to 110 {mu}M. In order to determine whether strain F could control sulfide production under optimal conditions for sulfate-reducing bacteria, the electron donor was changed to lactate and inorganic nutrients (nitrogen and phosphate sources) were added to the formation water. When nutrient-supplemented formation water with 3.1 mM lactate and 10 mM nitrate was used, the effluent sulfide concentrations of the control core system initially increased to about 3,800 {mu}M, and then decreased to about 1,100 {mu}M after 5 weeks. However, in the test core system inoculated with strain F, the effluent sulfide concentrations were much lower, 160 to 330 {mu}M.

  12. Carbon and sulfur relationships in Devonian shales from the Appalachian Basin as an indicator of environment of deposition.

    Science.gov (United States)

    Leventhal, J.S.

    1987-01-01

    Interprets the covariance of organic carbon and sulfide sulfur in core samples. This covariance results from the catabolism of organic carbon and concomitant reduction of sulfate by sulfate reducing bacteria to form aqueous sulfide which reacts with iron. Defines a central basin area that was the most anoxic-sulfidic (euxinic). This part of the basin is similar to the area of thickest, most organic carbon-rich sediments and has the greatest source-rock potential for petroleum. -from Author

  13. Removal of methanethiol, dimethyl sulfide, dimethyl disulfide, and hydrogen sulfide from contaminated air by Thiobacillus thioparus TK-m.

    OpenAIRE

    Kanagawa, T; Mikami, E.

    1989-01-01

    Methanethiol, dimethyl sulfide, dimethyl disulfide, and hydrogen sulfide were efficiently removed from contaminated air by Thiobacillus thioparus TK-m and oxidized to sulfate stoichiometrically. More than 99.99% of dimethyl sulfide was removed when the load was less than 4.0 g of dimethyl sulfide per g (dry cell weight) per day.

  14. Modeling the Effect of Dissolved Hydrogen Sulfide on Mg2+-water Complex on Dolomite {104} Surfaces

    CERN Document Server

    Shen, Zhizhang; Brown, Philip E; Szlufarska, Izabela; Xu, Huifang

    2016-01-01

    The key kinetic barrier to dolomite formation is related to the surface Mg2+-H2O complex, which hinders binding of surface Mg2+ ions to the CO3 2- ions in solution. It has been proposed that this reaction can be catalyzed by dissolved hydrogen sulfide. To characterize the role of dissolved hydrogen sulfide in the dehydration of surface Mg 2+ ions, ab initio simulations based on density functional theory (DFT) were carried out to study the thermodynamics of competitive adsorption of hydrogen sulfide and water on dolomite (104) surfaces from solution. We find that water is thermodynamically more stable on the surface with the difference in adsorption energy of -13.6 kJ/mol (in vacuum) and -12.8 kJ/mol (in aqueous solution). However, aqueous hydrogen sulfide adsorbed on the surface increases the Mg2+-H2O distances on surrounding surface sites. Two possible mechanisms were proposed for the catalytic effects of adsorbed hydrogen sulfide on the anhydrous Ca-Mg-carbonate crystallization at low temperature.

  15. Hydrogen Sulfide Induces Oxidative Damage to RNA and DNA in a Sulfide-Tolerant Marine Invertebrate

    OpenAIRE

    Joyner-Matos, Joanna; Predmore, Benjamin L.; Stein, Jenny R.; Leeuwenburgh, Christiaan; Julian, David

    2010-01-01

    Hydrogen sulfide acts as an environmental toxin across a range of concentrations and as a cellular signaling molecule at very low concentrations. Despite its toxicity, many animals, including the mudflat polychaete Glycera dibranchiata, are periodically or continuously exposed to sulfide in their environment. We tested the hypothesis that a broad range of ecologically relevant sulfide concentrations induces oxidative stress and oxidative damage to RNA and DNA in G. dibranchiata. Coelomocytes ...

  16. Nitrate-reducing, sulfide-oxidizing bacteria as microbial oxidants for rapid biological sulfide removal.

    Science.gov (United States)

    De Gusseme, Bart; De Schryver, Peter; De Cooman, Michaël; Verbeken, Kim; Boeckx, Pascal; Verstraete, Willy; Boon, Nico

    2009-01-01

    The emission of hydrogen sulfide into the atmosphere of sewer systems induces the biological production of sulfuric acid, causing severe concrete corrosion. As a possible preventive solution, a microbial consortium of nitrate-reducing, sulfide-oxidizing bacteria (NR-SOB) was enriched in a continuously stirred tank reactor in order to develop a biological technique for the removal of dissolved sulfide. The consortium, dominated by Arcobacter sp., was capable of removing 99% of sulfide. Stable isotope fractioning of the sulfide indicated that the oxidation was a biological process. The capacity of the NR-SOB consortium for rapid removal of sulfide was demonstrated by using it as an inoculum in synthetic and real sewage. Removal rates up to 52 mg sulfide-S g VSS(-1) h(-1) were achieved, to our knowledge the highest removal rate reported so far for freshwater species in the absence of molecular oxygen. Further long-term incubation experiments revealed the capacity of the bacteria to oxidize sulfide without the presence of nitrate, suggesting that an oxidized redox reserve is present in the culture.

  17. [Fatal outcome of an hydrogen sulfide poisoning].

    Science.gov (United States)

    Querellou, E; Jaffrelot, M; Savary, D; Savry, C; Perfus, J-P

    2005-10-01

    We report a case of fatal outcome poisoning by massive exposure to hydrogen sulfide of a sewer worker. This rare event was associated with a moderate intoxication of two members of the rescue team. The death was due to asystole and massive lung oedema. Autopsy analysis showed diffuse necrotic lesions in lungs. Hydrogen sulfide is a direct and systemic poison, produced by organic matter decomposition. The direct toxicity mechanism is still unclear. The systemic toxicity is due to an acute toxicity by oxygen depletion at cellular level. It is highly diffusable and potentially very dangerous. At low concentration, rotten egg smell must trigger hydrogen sulfide suspicion since at higher concentration it is undetectable, making intoxication possible. In case of acute intoxication, there is an almost instantaneous cardiovascular failure and a rapid death. Hydrogen sulfide exposure requires prevention measures and more specifically the use of respiratory equipment for members of the rescue team.

  18. Mechanism of mechanical activation for sulfide ores

    Institute of Scientific and Technical Information of China (English)

    HU Hui-ping; CHEN Qi-yuan; YIN Zhou-lan; HE Yue-hui; HUANG Bai-yun

    2007-01-01

    Structural changes for mechanically activated pyrite, sphalerite, galena and molybdenite with or without the exposure to ambient air, were systematically investigated using X-ray diffraction analysis(XRD), particle size analysis, gravimetrical method, X-ray photo-electron spectroscopy(XPS) and scanning electron microscopy(SEM), respectively. Based on the above structural changes for mechanically activated sulfide ores and related reports by other researchers, several qualitative rules of the mechanisms and the effects of mechanical activation for sulfide ores are obtained. For brittle sulfide ores with thermal instability, and incomplete cleavage plane or extremely incomplete cleavage plane, the mechanism of mechanical activation is that a great amount of surface reactive sites are formed during their mechanical activation. The effects of mechanical activation are apparent. For brittle sulfide ores with thermal instability, and complete cleavage plane, the mechanism of mechanical activation is that a great amount of surface reactive sites are formed, and lattice deformation happens during their mechanical activation. The effects of mechanical activation are apparent. For brittle sulfide ores with excellent thermal stability, and complete cleavage plane, the mechanism of mechanical activation is that lattice deformation happens during their mechanical activation. The effects of mechanical activation are apparent. For sulfide ores with high toughness, good thermal stability and very excellent complete cleavage plane, the mechanism of mechanical activation is that lattice deformation happens during their mechanical activation, but the lattice deformation ratio is very small. The effects of mechanical activation are worst.

  19. Degradation of sulfide linkages between isoprenes by lipid peroxidation catalyzed by manganese peroxidase.

    Science.gov (United States)

    Sato, Shin; Ohashi, Yasunori; Kojima, Masaaki; Watanabe, Takahito; Honda, Yoichi; Watanabe, Takashi

    2009-10-01

    Scission of sulfide linkages in vulcanized rubber has been a major concern since the early 20th century, because devulcanization is a key process for recycling waste rubber products as polymer materials that pose low environmental risks. We herein demonstrate that lipid peroxidation (LPO) of linoleic acid by manganese peroxidase (MnP), a proposed lignin-degradation system in the early stage of selective white rot fungi, cleaves sulfide bond in a model rubber compound, di(2-methylpent-2-enyl) sulfide, to 2,4-dimethylthiophene and 2-methyl-2-pentenal. The major intermediate of the LPO process, 2,4-decadienal was directly oxidized by MnP to cleave the sulfur-carbon bond. We propose that electrophilic radicals from 2,4-decadienal abstract one electron from a sulfur atom of the model compound to produce the sulfur radical cation intermediate, which in turn reacts with molecular oxygen to cleave the sulfur-carbon bond. The discovery of free radical-mediated scission of sulfide bond coupled with Mn oxidation provides a novel strategy for recycling vulcanized rubber wastes.

  20. Hydrogen sulfide can inhibit and enhance oxygenic photosynthesis in a cyanobacterium from sulfidic springs

    NARCIS (Netherlands)

    Klatt, Judith M.; Haas, Sebastian; Yilmaz, Pelin; de Beer, Dirk; Polerecky, Lubos

    2015-01-01

    We used microsensors to investigate the combinatory effect of hydrogen sulfide (H2S) and light on oxygenic photosynthesis in biofilms formed by a cyanobacterium from sulfidic springs. We found that photosynthesis was both positively and negatively affected by H2S: (i) H2S accelerated the recovery of

  1. Sulfide response analysis for sulfide control using a pS electrode in sulfate reducing bioreactors

    NARCIS (Netherlands)

    Villa Gomez, D.K.; Cassidy, J.; Keesman, K.J.; Sampaio, R.M.; Lens, P.N.L.

    2014-01-01

    Step changes in the organic loading rate (OLR) through variations in the influent chemical oxygen demand (CODin) concentration or in the hydraulic retention time (HRT) at constant COD/SO4 2- ratio (0.67) were applied to create sulfide responses for the design of a sulfide control in sulfate reducing

  2. Hydrogen sulfide induces oxidative damage to RNA and DNA in a sulfide-tolerant marine invertebrate.

    Science.gov (United States)

    Joyner-Matos, Joanna; Predmore, Benjamin L; Stein, Jenny R; Leeuwenburgh, Christiaan; Julian, David

    2010-01-01

    Hydrogen sulfide acts as an environmental toxin across a range of concentrations and as a cellular signaling molecule at very low concentrations. Despite its toxicity, many animals, including the mudflat polychaete Glycera dibranchiata, are periodically or continuously exposed to sulfide in their environment. We tested the hypothesis that a broad range of ecologically relevant sulfide concentrations induces oxidative stress and oxidative damage to RNA and DNA in G. dibranchiata. Coelomocytes exposed in vitro to sulfide (0-3 mmol L(-1) for 1 h) showed dose-dependent increases in oxidative stress (as 2',7'-dichlorofluorescein fluorescence) and superoxide production (as dihydroethidine fluorescence). Coelomocytes exposed in vitro to sulfide (up to 0.73 mmol L(-1) for 2 h) also acquired increased oxidative damage to RNA (detected as 8-oxo-7,8-dihydroguanosine) and DNA (detected as 8-oxo-7,8-dihydro-2'-deoxyguanosine). Worms exposed in vivo to sulfide (0-10 mmol L(-1) for 24 h) acquired elevated oxidative damage to RNA and DNA in both coelomocytes and body wall tissue. While the consequences of RNA and DNA oxidative damage are poorly understood, oxidatively damaged deoxyguanosine bases preferentially bind thymine, causing G-T transversions and potentially causing heritable point mutations. This suggests that sulfide can be an environmental mutagen in sulfide-tolerant invertebrates.

  3. Indium sulfide buffer/CIGSSe interface engineering: Improved cell performance by the addition of zinc sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Allsop, N.A. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany)]. E-mail: allsop@hmi.de; Camus, C. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany); Haensel, A. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany); Gledhill, S.E. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany); Lauermann, I. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany); Lux-Steiner, M.C. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany); Fischer, Ch.-H. [Hahn-Meitner-Institut Berlin, Department SE2, Glienicker Str. 100, D-14109 Berlin (Germany)

    2007-05-31

    Indium sulfide buffer layers deposited by the spray-ion layer gas reaction (Spray-ILGAR) technique are a viable alternative to the traditional cadmium sulfide buffer layer in thin film solar cells. In the present work we report on the results of manipulating the absorber/buffer interface between the chalcopyrite Cu(In,Ga)(S,Se){sub 2} absorber (CIGSSe) and the indium sulfide buffer. It is shown that the deposition of a small amount of zinc sulfide at the absorber/buffer interface can be used to increase the open circuit voltage. A small but significant increase of 20 mV (up to 580 mV), as compared to the pure indium sulfide buffered cells is possible leading to an increase in the overall efficiency.

  4. 炭基材料干法脱除硫化氢的研究进展%Research on carbon-based materials for hydrogen sulfide removal in dry process

    Institute of Scientific and Technical Information of China (English)

    韩鹏; 郑仙荣; 张肖阳; 常丽萍

    2014-01-01

    With the advantages of the well developed pore structures and the abundant functional groups,carbon-based materials are widely used in dry desulfurization process. According to various reactions in desulfurization process,sorbents from carbon-based materials are mainly classified into two types. One is used to adsorb H2S directly as a sorbent. The other is used as the support for loading active components,by which H2S is removed by the interaction between metal active components and sulphur. The research progress in dry desulfurization was reviewed in detail in this article. In order to illustrate the process concretely , the effects of temperature and atmosphere on desulfurization behaviors have been analyzed. The relationship of its desulfurization capacity with the modified activation methods and the preparation conditions of carbon-based materials sorbent were also investigated. Compared with wet desulfurization,the carbon-based materials in dry desulfurization method is attractive by its cheap price,availability,high-desulfurization rate,and no heat transfer process needed. Thus the method has more merits and broad research prospect than the traditional desulfurization.%炭基材料因其发达的孔隙结构和丰富的官能团而被广泛用于 H2S 的干法脱除,基于其在脱硫过程中所起作用的不同可分为两大类:一类是利用炭基材料本身的物化特性直接作为吸附剂脱除H2S;另一类是炭基材料作为载体负载金属氧化物制备成吸附剂,利用金属组分与硫的作用脱除 H2S。本文详细综述了炭基材料干法脱除H2S的研究进展,具体分析了不同类型炭基吸附剂脱除H2S时的温度、气氛等条件对其脱硫行为的影响以及改性活化方法和制备工艺与其脱硫能力间的关系。由于炭基材料干法脱除 H2S 的过程相对湿法脱除省去换热过程,且炭基材料廉价易得,有很高的脱硫率,所以其比传统的脱硫工艺更具优势和研究前景。

  5. Oxygen-free atomic layer deposition of indium sulfide.

    Science.gov (United States)

    McCarthy, Robert F; Weimer, Matthew S; Emery, Jonathan D; Hock, Adam S; Martinson, Alex B F

    2014-08-13

    Atomic layer deposition (ALD) of indium sulfide (In2S3) films was achieved using a newly synthesized indium precursor and hydrogen sulfide. We obtain dense and adherent thin films free from halide and oxygen impurities. Self-limiting half-reactions are demonstrated at temperatures up to 225 °C, where oriented crystalline thin films are obtained without further annealing. Low-temperature growth of 0.89 Å/cycle is observed at 150 °C, while higher growth temperatures gradually reduce the per-cycle growth rate. Rutherford backscattering spectroscopy (RBS) together with depth-profiling Auger electron spectroscopy (AES) reveal a S/In ratio of 1.5 with no detectable carbon, nitrogen, halogen, or oxygen impurities. The resistivity of thin films prior to air exposure decreases with increasing deposition temperature, reaching In2S3 via ALD at temperatures up to 225 °C may allow high quality thin films to be leveraged in optoelectronic devices including photovoltaic absorbers, buffer layers, and intermediate band materials.

  6. Effect of dissolved oxygen on elemental sulfur generation in sulfide and nitrate removal process: characterization, pathway, and microbial community analysis.

    Science.gov (United States)

    Wang, Xiaowei; Zhang, Yu; Zhang, Tingting; Zhou, Jiti

    2016-03-01

    Microaerobic bioreactor treatment for enriched sulfide and nitrate has been demonstrated as an effective strategy to improve the efficiencies of elemental sulfur (S(0)) generation, sulfide oxidation, and nitrate reduction. However, there is little detailed information for the effect and mechanism of dissolved oxygen (DO) on the variations of microbial community in sulfur generation, sulfide oxidation, and nitrate reduction systems. Polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) was employed to evaluate the variations of microbial community structures in a sulfide oxidation and nitrate reduction reactor under different DO conditions (DO 0-0.7 mg · L(-1)). Experimental results revealed that the activity of sulfide-oxidizing bacteria (SOB) and nitrate-reducing bacteria (NRB) could be greatly stimulated in 0.1-0.3 mg-DO · L(-1). However, when the DO concentration was further elevated to more than 0.5 mg · L(-1), the abundance of NRB was markedly decreased, while the heterotrophic microorganisms, especially carbon degradation species, were enriched. The reaction pathways for sulfide and nitrate removal under microaerobic conditions were also deduced by combining batch experiments with functional species analysis. It was likely that the oxidation of sulfide to sulfur could be performed by both aerobic heterotrophic SOB and sulfur-based autotrophic denitrification bacteria with oxygen and nitrate as terminal electron acceptor, respectively. The nitrate could be reduced to nitrite by both autotrophic and heterotrophic denitrification, and then the generated nitrite could be completely converted to nitrogen gas via heterotrophic denitrification. This study provides new insights into the impacts of microaerobic conditions on the microbial community functional structures of sulfide-oxidizing, nitrate-reducing, and sulfur-producing bioreactors, which revealing the potential linkage between functional microbial communities and

  7. A study of the stability of cadmium sulfide/copper sulfide and cadmium sulfide copper-indium-diselenide solar cells

    Science.gov (United States)

    Noel, G.; Richard, N.; Gaines, G.

    1984-08-01

    Groups of high efficiency cadmium sulfide/copper sulfide solar cells were exposed to combinations of stresses designed to isolate and accelerate intrinsic degradation mechanisms. Stresses included elevated temperature, illumination intensity, and cell loading conditions. All stress exposures and tests were conducted in a benign (high purity argon) atmosphere. Two primary intrinsic modes of degradation were identified: degradation of the open circuit voltage under continuous illumination and nonzero loading was found to be self recovering upon interruption of illumination or upon shorting or reverse biasing the cells. It was attributed to traps in the depletion region. Recovery from decay of light generated current was not spontaneous but could be partially accomplished by annealing in a reducing (hydrogen) environment. It was attributed to changes in the stoichiometry of the copper sulfide under the influence of electric fields and currents.

  8. Sulfide capacities of fayalite-base slags

    Science.gov (United States)

    Simeonov, S. R.; Sridhar, R.; Toguri, J. M.

    1995-04-01

    The sulfide capacities of fayalite-base slags were measured by a gas-slag equilibration technique under controlled oxygen and sulfur potentials similar to those encountered in the pyrometallurgical processing of nonferrous metals. The oxygen pressure range was from 10-9.5 to 10-11 MPa and the sulfur pressure range from 10-3 to 10-4.5 MPa, over a temperature range of 1473 to 1623 K. The slags studied were FeO-SiO2 at silica saturation and those with addition of CaO, MgO, and Al2O3 to determine their effect on sulfide capacities. For these slags, the sulfide capacities were found to vary from 10-3.3 to 10-5. The sulfide capacities increased with increasing temperature from 1473 to 1623 K. A comparison of the reported plant data on sulfur content of industrial slags shows good agreement with the present experimental results. The present data will be useful in estimating metal losses in slag due to metal sulfide entrainment in nonferrous smelters.

  9. The role of sulfur trapped in micropores in the catalytic partial oxidation of hydrogen sulfide with oxygen

    NARCIS (Netherlands)

    Steijns, M.; Mars, P.

    1974-01-01

    The catalytic oxidation of hydrogen sulfide into sulfur with molecular oxygen has been studied in the temperature range 130–200 °C. Active carbon, molecular sieve 13X and liquid sulfur were used as catalysts. Sulfur is adsorbed in the micropores (3 < r < 40 Å) of the catalysts. Experiments with a su

  10. Anoxygenic Photosynthesis Controls Oxygenic Photosynthesis in a Cyanobacterium from a Sulfidic Spring

    OpenAIRE

    Klatt, Judith M.; Al-Najjar, Mohammad A. A.; Yilmaz, Pelin; Lavik, Gaute; de Beer, Dirk; Polerecky, Lubos

    2015-01-01

    Before the Earth's complete oxygenation (0.58 to 0.55 billion years [Ga] ago), the photic zone of the Proterozoic oceans was probably redox stratified, with a slightly aerobic, nutrient-limited upper layer above a light-limited layer that tended toward euxinia. In such oceans, cyanobacteria capable of both oxygenic and sulfide-driven anoxygenic photosynthesis played a fundamental role in the global carbon, oxygen, and sulfur cycle. We have isolated a cyanobacterium, Pseudanabaena strain FS39,...

  11. Sources and sinks of carbonyl sulfide in an agricultural field in the Southern Great Plains

    OpenAIRE

    Maseyk, Kadmiel; Berry, Joseph A; Billesbach, Dave; Campbell, John Elliott; Torn, Margaret S.; Zahniser, Mark; Seibt, Ulli

    2014-01-01

    Net photosynthesis is the largest single flux in the global carbon cycle, but controls over its variability are poorly understood because there is no direct way of measuring it at the ecosystem scale. We report observations of ecosystem carbonyl sulfide (COS) and CO2 fluxes that resolve key gaps in an emerging framework for using concurrent COS and CO2 measurements to quantify terrestrial gross primary productivity. At a wheat field in Oklahoma we found that in the peak growing season the flu...

  12. Litter dominates surface fluxes of carbonyl sulfide in a Californian oak woodland

    OpenAIRE

    Sun, Wu; Maseyk, Kadmiel; Lett, Céline; Seibt, Ulli

    2016-01-01

    Carbonyl sulfide (COS) is a promising tracer for partitioning terrestrial photosynthesis and respiration from net carbon fluxes, based on its daytime co-uptake alongside CO2 through leaf stomata. Because ecosystem COS fluxes are the sum of plant and soil fluxes, using COS as a photosynthesis tracer requires accurate knowledge of soil COS fluxes. At an oak woodland in Southern California, we monitored below-canopy surface (soil + litter) COS and CO2 fluxes for 40 days using chambers and laser ...

  13. Solar thermal extraction of copper from sulfides

    Energy Technology Data Exchange (ETDEWEB)

    Winkel, L.; Guesdon, C.; Sturzenegger, M.

    2003-03-01

    With the aim to develop a solar-driven process for the extraction of copper from sulfide concentrates re-search on the decomposition of copper sulfides under inert atmospheres has been initiated. Thermogravimetric measurements on chalcocite (Cu{sub 2}S) revealed that copper is formed already at 1823 K. Chalcopyrite (CuFeS{sub 2}) also disintegrates at this temperature, although at a lower rate. Copper and iron have been identified in the solid residue. The results confirm the feasibility of copper extraction by direct decomposition of sulfides under atmospheric pressure. The decomposition under inert atmosphere prevents generation of SO{sub 2}, and is beneficial to the removal of volatile impurities. Chemical equilibrium calculations for CuFeS{sub 2} contaminated with enargite (Cu{sub 3}AsS{sub 4}) have shown that the absence of an oxidic slag allows for a complete evaporation of arsenic and subsequent separation. (author)

  14. An array of layers in silicon sulfides: Chainlike and monolayer

    Science.gov (United States)

    Alonso-Lanza, T.; Ayuela, A.; Aguilera-Granja, F.

    2016-12-01

    While much is known about isoelectronic materials related to carbon nanostructures, such as boron-nitride layers and nanotubes, rather less is known about equivalent silicon-based materials. Following the recent discovery of phosphorene, here we discuss isoelectronic silicon-monosulfide monolayers. We describe a set of anisotropic structures that clearly have a high stability with respect to previously reported silicon-monosulfide monolayers. The source of the layer anisotropy is related to the presence of Si-S double chains linked by some Si-Si covalent bonds together with a remarkable spd hybridization on Si. The increased stability is related to silicon forming four bonds, including an additional double-bond-like Si-Si bond. The involvement of d orbitals brings more variety to silicon-sulfide-based nanostructures that are isoelectronic to phosphorene, which could be relevant for future applications, adding extra degrees of freedom.

  15. Hydrogen Sulfide, Oxidative Stress and Periodontal Diseases: A Concise Review

    Science.gov (United States)

    Greabu, Maria; Totan, Alexandra; Miricescu, Daniela; Radulescu, Radu; Virlan, Justina; Calenic, Bogdan

    2016-01-01

    In the past years, biomedical research has recognized hydrogen sulfide (H2S) not only as an environmental pollutant but also, along with nitric oxide and carbon monoxide, as an important biological gastransmitter with paramount roles in health and disease. Current research focuses on several aspects of H2S biology such as the biochemical pathways that generate the compound and its functions in human pathology or drug synthesis that block or stimulate its biosynthesis. The present work addresses the knowledge we have to date on H2S production and its biological roles in the general human environment with a special focus on the oral cavity and its involvement in the initiation and development of periodontal diseases. PMID:26805896

  16. Lithium sulfide compositions for battery electrolyte and battery electrode coatings

    Science.gov (United States)

    Liang, Chengdu; Liu, Zengcai; Fu, Wunjun; Lin, Zhan; Dudney, Nancy J; Howe, Jane Y; Rondinone, Adam J

    2013-12-03

    Methods of forming lithium-containing electrolytes are provided using wet chemical synthesis. In some examples, the lithium containing electroytes are composed of .beta.-Li.sub.3PS.sub.4 or Li.sub.4P.sub.2S.sub.7. The solid electrolyte may be a core shell material. In one embodiment, the core shell material includes a core of lithium sulfide (Li.sub.2S), a first shell of .beta.-Li.sub.3PS.sub.4 or Li.sub.4P.sub.2S.sub.7, and a second shell including one or .beta.-Li.sub.3PS.sub.4 or Li.sub.4P.sub.2S.sub.7 and carbon. The lithium containing electrolytes may be incorporated into wet cell batteries or solid state batteries.

  17. P-O-rich sulfide phase in CM chondrites: Constraints on its origin on the CM parent body

    Science.gov (United States)

    Zhang, Ai-Cheng; Itoh, Shoichi; Yurimoto, Hisayoshi; Hsu, Wei-Biao; Wang, Ru-Cheng; Taylor, Lawrence A.

    2016-01-01

    CM chondrites are a group of primitive meteorites that have recorded the alteration history of the early solar system. We report the occurrence, chemistry, and oxygen isotopic compositions of P-O-rich sulfide phase in two CM chondrites (Grove Mountains [GRV] 021536 and Murchison). This P-O-rich sulfide is a polycrystalline aggregate of nanometer-size grains. It occurs as isolated particles or aggregates in both CM chondrites. These grains, in the matrix and in type-I chondrules from Murchison, were partially altered into tochilinite; however, grains enclosed by Ca-carbonate are much less altered. This P-O-rich sulfide in Murchison is closely associated with magnetite, FeNi phosphide, brezinaite (Cr3S4), and eskolaite (Cr2O3). In addition to sulfur as the major component, this sulfide contains ~6.3 wt% O, ~5.4 wt% P, and minor amounts of hydrogen. Analyses of oxygen isotopes by SIMS resulted in an average δ18O value of -22.5 ‰ and an average Δ17O value of 0.2 ± 9.2 ‰ (2σ). Limited variations in both chemical compositions and electron-diffraction patterns imply that the P-O-rich sulfide may be a single phase rather than a polyphase mixture. Several features indicate that this P-O-rich sulfide phase formed at low temperature on the parent body, most likely through the alteration of FeNi metal (a) close association with other low-temperature alteration products, (b) the presence of hydrogen, (c) high Δ17O values and the presence in altered mesostasis of type-I chondrules and absence in type-II chondrules. The textural relations of the P-O-rich sulfide and other low-temperature minerals reveal at least three episodic-alteration events on the parent body of CM chondrites (1) formation of P-O-rich sulfide during sulfur-rich aqueous alteration of P-rich FeNi metal, (2) formation of Ca-carbonate during local carbonation, and (3) alteration of P-O-rich sulfide and formation of tochilinite during a period of late-stage intensive aqueous alteration.

  18. Membrane for hydrogen recovery from streams containing hydrogen sulfide

    Science.gov (United States)

    Agarwal, Pradeep K.

    2007-01-16

    A membrane for hydrogen recovery from streams containing hydrogen sulfide is provided. The membrane comprises a substrate, a hydrogen permeable first membrane layer deposited on the substrate, and a second membrane layer deposited on the first layer. The second layer contains sulfides of transition metals and positioned on the on a feed side of the hydrogen sulfide stream. The present invention also includes a method for the direct decomposition of hydrogen sulfide to hydrogen and sulfur.

  19. Modeling of Sulfide Microenvironments on Mars

    Science.gov (United States)

    Schwenzer, S. P.; Bridges, J. C.; McAdam, A.; Steer, E. D.; Conrad, P. G.; Kelley, S. P.; Wiens, R. C.; Mangold, N.; Grotzinger, J.; Eigenbrode, J. L.; Franz, H. B.; Sutter, B.

    2016-01-01

    Yellowknife Bay (YKB; sol 124-198) is the second site that the Mars Science Laboratory Rover Curiosity investigated in detail on its mission in Gale Crater. YKB represents lake bed sediments from an overall neutral pH, low salinity environment, with a mineralogical composition which includes Ca-sulfates, Fe oxide/hydroxides, Fe-sulfides, amorphous material, and trioctahedral phyllosilicates. We investigate whether sulfide alteration could be associated with ancient habitable microenvironments in the Gale mudstones. Some textural evidence for such alteration may be pre-sent in the nodules present in the mudstone.

  20. Iron-sulfide crystals in probe deposits

    DEFF Research Database (Denmark)

    Laursen, Karin; Frandsen, Flemming

    1998-01-01

    Iron-sulfides were observed in deposits collected on a probe inserted at the top of the furnace of a coal-fired power station in Denmark. The chemical composition of the iron-sulfides is equivalent to pyrrhotite (FeS). The pyrrhotites are present as crystals and, based on the shape of the crystals......, it was deduced that they were not deposited but instead grew within the deposit. The presence of unburned char particles within the deposits supports the concept that a reducing environment existed in the deposits. Two processes are proposed for explaining the existence of pyrrhotite crystals within a deposit...

  1. Mineralizing conditions and source fluid composition of base metal sulfides in the Lon District, southeastern Iceland

    Science.gov (United States)

    Kremer, C. H.; Thomas, D.; García del Real, P.; Zierenberg, R. A.; Bird, D. K.

    2014-12-01

    Hydrothermal base metal mineralization is rare in Iceland due to the scarcity of evolved magma bodies that discharge metal-rich aqueous fluids into bedrock. One exception is the Lon District of southeastern Iceland, where explosively emplaced rhyolitic breccias host base metal sulfide minerals. We performed petrographic, fluid inclusion, and stable isotope analyses on samples collected in Lon to constrain the conditions of sulfide mineral formation. Based on outcrop and hand sample observations, hot, early-stage hydrothermal fluids precipitated sulfide minerals, quartz, and epidote in rhyolitic breccia and basalt flows. Cooler late-stage fluids precipitated carbonates and quartz in rhyolitic breccia and basalt flows. The order of precipitation of the sulfides was: galena, sphalerite, then chalcopyrite. Homogenization temperatures of liquid-dominated multi-phase fluid inclusions in hydrothermal early-stage quartz coeval with chalcopyrite cluster around 303 °C and 330 °C, indicating precipitation of metallic sulfides in two main hydrothermal fluid pulses early in the period of hydrothermal activity in the Lon District. Freezing point depression analyses of fluid inclusions in quartz show that the sulfide minerals precipitated from a solution that was 4 wt. % NaCl. The 𝛿34S values of sulfides indicate that early-stage hydrothermal sulfur was derived from igneous rocks, either through leaching by non-magmatic hydrothermal fluids or by exsolution of magmatic waters. Early stage epidote 𝛿D values were on average -65.96 per mil, about 14 per mil higher than reported values in epidotes from elsewhere in southeastern Iceland. The 𝛿13C and 𝛿18O values of late-stage carbonates indicate that late stage hydrothermal fluids were meteoric in origin. Collectively, fluid inclusion and stable isotope analyses suggest that early-stage aqueous fluids derived from a mixture of magmatic waters exsolved from the proximal Geitafell intrusion and meteoric

  2. Use of biogenic sulfide for ZnS precipitation

    NARCIS (Netherlands)

    Esposito, G.; Veeken, A.; Weijma, J.; Lens, P.N.L.

    2006-01-01

    A 600 ml continuously stirred tank reactor was used to assess the performance of a zinc sulfide precipitation process using a biogenic sulfide solution (the effluent of a sulfate-reducing bioreactor) as sulfide source. In all experiments, a proportional-integral (PI) control algorithm was used to co

  3. A physiologically based kinetic model for bacterial sulfide oxidation

    NARCIS (Netherlands)

    Klok, J.B.; Graaff, M. de; Bosch, P.L. van den; Boelee, N.C.; Keesman, K.J.; Janssen, A.J.W.M.

    2013-01-01

    In the biotechnological process for hydrogen sulfide removal from gas streams, a variety of oxidation products can be formed. Under natron-alkaline conditions, sulfide is oxidized by haloalkaliphilic sulfide oxidizing bacteria via flavocytochrome c oxidoreductase. From previous studies, it was concl

  4. Measurement and biological significance of the volatile sulfur compounds hydrogen sulfide, methanethiol and dimethyl sulfide in various biological matrices.

    NARCIS (Netherlands)

    Tangerman, A.

    2009-01-01

    This review deals with the measurement of the volatile sulfur compounds hydrogen sulfide, methanethiol and dimethyl sulfide in various biological matrices of rats and humans (blood, serum, tissues, urine, breath, feces and flatus). Hydrogen sulfide and methanethiol both contain the active thiol (-SH

  5. Measurement and biological significance of the volatile sulfur compounds hydrogen sulfide, methanethiol and dimethyl sulfide in various biological matrices

    NARCIS (Netherlands)

    Tangerman, Albert

    2009-01-01

    This review deals with the measurement of the volatile Sulfur compounds hydrogen sulfide, methanethiol and dimethyl sulfide in various biological matrices of rats and humans (blood, serum, tissues, urine, breath, feces and flatus). Hydrogen sulfide and methanethiol both contain the active thiol (-SH

  6. Modeling Sulfides, pH and Hydrogen Sulfide Gas in the Sewers of San Francisco

    DEFF Research Database (Denmark)

    Vollertsen, Jes; Revilla, Nohemy; Hvitved-Jacobsen, Thorkild;

    2015-01-01

    An extensive measuring campaign targeted on sewer odor problems was undertaken in San Francisco. It was assessed whether a conceptual sewer process model could reproduce the measured concentrations of total sulfide in the wastewater and H2S gas in the sewer atmosphere, and to which degree...... such simulations have potential for further improving odor and sulfide management. The campaign covered measurement of wastewater sulfide by grab sampling and diurnal sampling, and H2S gas in the sewer atmosphere was logged. The tested model was based on the Wastewater Aerobic/Anaerobic Transformations in Sewers...... (WATS) sewer process concept, which never had been calibrated to such an extensive dataset. The study showed that the model was capable of reproducing the general levels of wastewater sulfide, wastewater pH, and sewer H2S gas. It could also reproduce the general variability of these parameters, albeit...

  7. Comparison of Hydrogen Sulfide Analysis Techniques

    Science.gov (United States)

    Bethea, Robert M.

    1973-01-01

    A summary and critique of common methods of hydrogen sulfide analysis is presented. Procedures described are: reflectance from silver plates and lead acetate-coated tiles, lead acetate and mercuric chloride paper tapes, sodium nitroprusside and methylene blue wet chemical methods, infrared spectrophotometry, and gas chromatography. (BL)

  8. 30 CFR 250.490 - Hydrogen sulfide.

    Science.gov (United States)

    2010-07-01

    ... been confirmed. Well-control fluid means drilling mud and completion or workover fluid as appropriate... OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Drilling Operations Hydrogen Sulfide § 250.490 Hydrogen... section when conducting drilling, well-completion/well-workover, and production operations in zones...

  9. Hydrogen Sulfide in Preeclampsia : Potential Therapeutic Implications

    NARCIS (Netherlands)

    Holwerda, Kim

    2015-01-01

    The thesis provide insights into the production and possible therapeutic effect of the gaseous molecule hydrogen sulfide (H2S) in preeclampsia (PE). H2S is an important molecule in the (human) body. It is among others involved in blood pressure regulation, stimulation of vascular growth and modulati

  10. Nucleation of mercury sulfide by dealkylation

    Science.gov (United States)

    Enescu, Mironel; Nagy, Kathryn L.; Manceau, Alain

    2016-12-01

    Metal sulfide minerals are assumed to form naturally at ambient conditions via reaction of a metallic element with (poly)sulfide ions, usually produced by microbes in oxygen-depleted environments. Recently, the formation of mercury sulfide (β-HgS) directly from linear Hg(II)-thiolate complexes (Hg(SR)2) in natural organic matter and in cysteine solutions was demonstrated under aerated conditions. Here, a detailed description of this non-sulfidic reaction is provided by computations at a high level of molecular-orbital theory. The HgS stoichiometry is obtained through the cleavage of the S-C bond in one thiolate, transfer of the resulting alkyl group (R’) to another thiolate, and subsequent elimination of a sulfur atom from the second thiolate as a thioether (RSR’). Repetition of this mechanism leads to the formation of RS-(HgS)n-R chains which may self-assemble in parallel arrays to form cinnabar (α-HgS), or more commonly, quickly condense to four-coordinate metacinnabar (β-HgS). The mechanistic pathway is thermodynamically favorable and its predicted kinetics agrees with experiment. The results provide robust theoretical support for the abiotic natural formation of nanoparticulate HgS under oxic conditions and in the absence of a catalyst, and suggest a new route for the (bio)synthesis of HgS nanoparticles with improved technological properties.

  11. Platinum metals in magmatic sulfide ores

    Science.gov (United States)

    Naldrett, A.J.; Duke, J.M.

    1980-01-01

    Platinum-group elements (PGE) are mined predominantly from deposits that have formed by the segregation of molten iron-nickel-copper sulfides from silicate magmas. The absolute concentrations of PGE in sulfides from different deposits vary over a range of five orders of magnitude, whereas those of other chalcophile elements vary by factors of only 2 to 100. However, the relative proportions of the different PGE in a given deposit are systematically related to the nature of the parent magma. The absolute and relative concentrations of PGE in magmatic sulfides are explained in terms of the degree of partial melting of mantle peridotite required to produce the parent magma and the processes of batch equilibration and fractional segregation of sulfides. The Republic of South Africa and the U.S.S.R. together possess more than 97 percent of the world PGE reserves, but significant undeveloped resources occur in North America. The Stillwater complex in Montana is perhaps the most important example. Copyright ?? 1980 AAAS.

  12. Monitoring sulfide and sulfate-reducing bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Tanner, R.S.

    1995-12-31

    Simple yet precise and accurate methods for monitoring sulfate-reducing bacteria (SRB) and sulfide remain useful for the study of bacterial souring and corrosion. Test kits are available to measure sulfide in field samples. A more precise methylene blue sulfide assay for both field and laboratory studies is described here. Improved media, compared to that in API RP-38, for enumeration of SRB have been formulated. One of these, API-RST, contained cysteine (1.1 mM) as a reducing agent, which may be a confounding source of sulfide. While cysteine was required for rapid enumeration of SRB from environmental samples, the concentration of cysteine in medium could be reduced to 0.4 mM. It was also determined that elevated levels of yeast extract (>1 g/liter) could interfere with enumeration of SRB from environmental samples. The API-RST medium was modified to a RST-11 medium. Other changes in medium composition, in addition to reduction of cysteine, included reduction of the concentration of phosphate from 3.4 mM to 2.2 mM, reduction of the concentration of ferrous iron from 0.8 mM to 0.5 mM and preparation of a stock mineral solution to ease medium preparation. SRB from environmental samples could be enumerated in a week in this medium.

  13. Reduction of Sulfur Dioxide on Carbons Catalyzed by Salts

    OpenAIRE

    2005-01-01

    Abstract. The reduction of SO2 on different carbons in the presence of the nitrates and sulfides of sodium, potassium and calcium and potassium polysulfides was studied. The presence of salts increased the initial rate 2-5 fold for all of them and did not change the product distribution. The catalysis was not determined by the cation and there was no difference in the catalytic reactivity between nitrates and sulfides. The sulfur content of the activated carbon increased during the reaction o...

  14. Sulfide Intrusion and Detoxification in the Seagrass Zostera marina

    DEFF Research Database (Denmark)

    Hasler-Sheetal, Harald; Holmer, Marianne

    2015-01-01

    Gaseous sulfide intrusion into seagrasses growing in sulfidic sediments causes little or no harm to the plant, indicating the presence of an unknown sulfide tolerance or detoxification mechanism. We assessed such mechanism in the seagrass Zostera marina in the laboratory and in the field with sca......Gaseous sulfide intrusion into seagrasses growing in sulfidic sediments causes little or no harm to the plant, indicating the presence of an unknown sulfide tolerance or detoxification mechanism. We assessed such mechanism in the seagrass Zostera marina in the laboratory and in the field...... with scanning electron microscopy coupled to energy dispersive X-ray spectroscopy, chromatographic and spectrophotometric methods, and stable isotope tracing coupled with a mass balance of sulfur compounds. We found that Z. marina detoxified gaseous sediment-derived sulfide through incorporation and that most...

  15. Sulfide removal by moderate oxygenation of anaerobic sludge environments

    Energy Technology Data Exchange (ETDEWEB)

    Van der Zee, F.P.; Villaverde, S.; Polanco, F. [Valladolid Univ., Valladolid (Spain). Dept. of Chemical Engineering; Garcia, P.A.

    2004-07-01

    Treating wastewater through anaerobic bioreactors results in the formation of hydrogen sulfide. The sulfide can be removed from the biogas by introducing air directly into the anaerobic bioreactor system. This study presents the results of batch experiments that provided a better insight into the fate of sulfur compounds and oxygen during microaerobic sulfide oxidation in granular sludge. It was shown that sulfide could be removed rapidly upon introduction of low amounts of oxygen to the sulfide-amended batch vials with granular sludge treating vinasse. Initially, the sulfide was oxidized to elemental sulfur, thiosulfate and polysulfide. Significant production of sulfate did not occur. The introduction of oxygen, however, could result in the growth of aerobic organic-chemical oxygen demand-oxidizing bacteria that compete with sulfide oxidation for oxygen. 6 refs., 1 tab., 1 fig.

  16. Synthesis of Nanoporous Metals, Oxides, Carbides, and Sulfides: Beyond Nanocasting.

    Science.gov (United States)

    Luc, Wesley; Jiao, Feng

    2016-07-19

    Nanoporous metal-based solids are of particular interest because they combine a large quantity of surface metal sites, interconnected porous networks, and nanosized crystalline walls, thus exhibiting unique physical and chemical properties compared to other nanostructures and bulk counterparts. Among all of the synthetic approaches, nanocasting has proven to be a highly effective method for the syntheses of metal oxides with three-dimensionally ordered porous structures and crystalline walls. A typical procedure involves a thermal annealing process of a porous silica template filled with an inorganic precursor (often a metal nitrate salt), which converts the precursor into a desired phase within the silica pores. The final step is the selective removal of the silica template in either a strong base or a hydrofluoric acid solution. In the past decade, nanocasting has become a popular synthetic approach and has enabled the syntheses of a variety of nanoporous metal oxides. However, there is still a lack of synthetic methods to fabricate nanoporous materials beyond simple metal oxides. Therefore, the development of new synthetic strategies beyond nanocasting has become an important direction. This Account describes new progress in the preparation of novel nanoporous metal-based solids for heterogeneous catalysis. The discussion begins with a method called dealloying, an effective method to synthesize nanoporous metals. The starting material is a metallic alloy containing two or more elements followed by a selective chemical or electrochemical leaching process that removes one of the preferential elements, resulting in a highly porous structure. Nanoporous metals, such as Cu, Ag, and CuTi, exhibit remarkable electrocatalytic properties in carbon dioxide reduction, oxygen reduction, and hydrogen evolution reactions. In addition, the syntheses of metal oxides with hierarchical porous structures are also discussed. On the basis of the choice of hard template, nanoporous

  17. Evaluation of feed COD/sulfate ratio as a control criterion for the biological hydrogen sulfide production and lead precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Velasco, Antonio [Direccion General del Centro Nacional de Investigacion y Capacitacion Ambiental-Instituto Nacional de Ecologia, Av. San Rafael Atlixco 186, Col. Vicentina. Iztapalapa, Mexico 09340, D.F. (Mexico)], E-mail: jvelasco@ine.gob.mx; Ramirez, Martha [Direccion General del Centro Nacional de Investigacion y Capacitacion Ambiental-Instituto Nacional de Ecologia, Av. San Rafael Atlixco 186, Col. Vicentina. Iztapalapa, Mexico 09340, D.F. (Mexico); Volke-Sepulveda, Tania [Departamento de Biotecnologia, UAM-Cuajimalpa, San Rafael Atlixco 186, Col. Vicentina. Iztapalapa, Mexico 09340, D.F. (Mexico); Gonzalez-Sanchez, Armando [Departamento de Ingenieria de Procesos, Universidad Autonoma Metropolitana-Iztapalapa, UAM-Cuajimalpa, San Rafael Atlixco 186, Col. Vicentina. Iztapalapa, Mexico 09340, D.F. (Mexico); Revah, Sergio [Departamento de Procesos y Tecnologia, UAM-Cuajimalpa, San Rafael Atlixco 186, Col. Vicentina. Iztapalapa, Mexico 09340, D.F. (Mexico)

    2008-03-01

    The ability of sulfate-reducing bacteria to produce hydrogen sulfide and the high affinity of sulfide to react with divalent metallic cations represent an excellent option to remove heavy metals from wastewater. Different parameters have been proposed to control the hydrogen sulfide production by anaerobic bacteria, such as the organic and sulfate loading rates and the feed COD/SO{sub 4}{sup 2-} ratio. This work relates the feed COD/SO{sub 4}{sup 2-} ratio with the hydrogen sulfide production and dissolved lead precipitation, using ethanol as carbon and energy source in an up-flow anaerobic sludge blanket reactor. A maximum dissolved sulfide concentration of 470 {+-} 7 mg S/L was obtained at a feed COD/SO{sub 4}{sup 2-} ratio of 2.5, with sulfate and ethanol conversions of approximately 94 and 87%, respectively. The lowest dissolved sulfide concentration (145 {+-} 10 mg S/L) was observed with a feed COD/SO{sub 4}{sup 2-} ratio of 0.67. Substantial amounts of acetate (510-1730 mg/L) were produced and accumulated in the bioreactor from ethanol oxidation. Although only incomplete oxidation of ethanol to acetate was observed, the consortium was able to remove 99% of the dissolved lead (200 mg/L) with a feed COD/SO{sub 4}{sup 2-} ratio of 1.5. It was found that the feed COD/SO{sub 4}{sup 2-} ratio could be an adequate parameter to control the hydrogen sulfide production and the consequent precipitation of dissolved lead.

  18. An examination of the factors controlling mercury methylation in sulfidic coastal marine sediments

    Science.gov (United States)

    Mason, R. P.; Hollweg, T. A.; Schartup, A.; Gilmour, C. C.

    2010-12-01

    The methylation of mercury (Hg) is an important step in the biogeochemical cycling and bioaccumulation of methylmercury in marine organisms. The rate of methylation is controlled by both the chemical bioavailability of Hg to methylating organisms and their activity. It is known that methylation rate decreases in sulfidic environments, especially in marine waters, but the exact mechanisms accounting for this decrease are not well-known. Modeling studies suggest that adsorption and precipitation reactions in the presence of sulfide decrease the fraction that is considered bioavailable Hg but current models predict an increase in porewater concentration at high sulfide levels, which is contrary to field observations. We have therefore focused on ascertaining why the models overestimate dissolved Hg at high sulfide levels. We have developed models that incorporate interactions between Hg, dissolved and particulate sulfide (both FeS and pyrite) and including interactions in the presence of elemental sulfur (i.e the formation of Hg-polysulfide complexes). Additionally, we are incorporating data from our studies examining the interactions between Hg and organic matter extracted from various marine ecosystems. We compare our model results, through correlation and geochemical modeling, with data from studies in the Chesapeake Bay and associated shelf and slope, and test the sensitivity of the model to the various dissolved and solid phase interactions, and the role of solid phase organic carbon and organic sulfur content in influencing the strength of partitioning. A geochemical model will be presented describing how sediment redox status influences the strength of Hg partitioning, the dissolved speciation and we will compare measured Hg methylation rate constants with our predictions of porewater bioavailable Hg concentration.

  19. Elevated corrosion rates and hydrogen sulfide in homes with 'Chinese Drywall'

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Joseph G.; MacIntosh, David L. [Environmental Health and Engineering, Inc., 117 Fourth Avenue, Needham, MA (United States); Harvard School of Public Health, 677 Huntington Avenue, Boston, MA (United States); Saltzman, Lori E. [U.S. Consumer Product Safety Commission, Bethesda, MD (United States); Baker, Brian J. [Environmental Health and Engineering, Inc., 117 Fourth Avenue, Needham, MA (United States); Matheson, Joanna M.; Recht, Joel R. [U.S. Consumer Product Safety Commission, Bethesda, MD (United States); Minegishi, Taeko; Fragala, Matt A.; Myatt, Theodore A. [Environmental Health and Engineering, Inc., 117 Fourth Avenue, Needham, MA (United States); Spengler, John D.; Stewart, James H. [Environmental Health and Engineering, Inc., 117 Fourth Avenue, Needham, MA (United States); Harvard School of Public Health, 677 Huntington Avenue, Boston, MA (United States); McCarthy, John F., E-mail: jmcccarthy@eheinc.com [Environmental Health and Engineering, Inc., 117 Fourth Avenue, Needham, MA (United States)

    2012-06-01

    In December 2008, the U.S. Consumer Product Safety Commission (CPSC) began receiving reports about odors, corrosion, and health concerns related to drywall originating from China. In response, a detailed environmental health and engineering evaluation was conducted of 41 complaint and 10 non-complaint homes in the Southeast U.S. Each home investigation included characterization of: 1) drywall composition; 2) indoor and outdoor air quality; 3) temperature, moisture, and building ventilation; and 4) copper and silver corrosion rates. Complaint homes had significantly higher hydrogen sulfide concentrations (mean 0.82 vs. < LOD {mu}g/m{sup 3}, p < 0.05), and significantly greater rates of copper sulfide and silver sulfide corrosion compared to non-complaint homes (Cu{sub 2}S: 476 vs. < 32 A/30 d, p < 0.01; Ag{sub 2}S: 1472 vs. 389 A/30 d, p < 0.01). The abundance of carbonate and strontium in drywall was also elevated in complaint homes, and appears to be useful objective marker of problematic drywall in homes that meet other screening criteria (e.g., constructed or renovated in 2006-2007, reports of malodor and accelerated corrosion). This research provides empirical evidence of the direct association between homes constructed with 'Chinese Drywall' in 2006-2007 and elevated corrosion rates and hydrogen sulfide concentrations in indoor air. - Highlights: Black-Right-Pointing-Pointer Environmental measurements in homes with and without 'Chinese Drywall' Black-Right-Pointing-Pointer Homes with 'Chinese Drywall' had higher hydrogen sulfide concentrations Black-Right-Pointing-Pointer Homes with 'Chinese Drywall' had elevated corrosion rates Black-Right-Pointing-Pointer Study provides empirical evidence of reported associations.

  20. Organic silicon compounds anf hydrogen sulfide removal from biogas by mineral and adsorbent

    Science.gov (United States)

    Choi, J.

    2015-12-01

    Biogas utilized for energy production needs to be free from organic silicon compounds and hydrogen sulfide , as their burning has damaging effects on utilities and humans; organic silicon compounds and hydrogen sulfide can be found in biogas produced from biomass wastes, due to their massive industrial use in synthetic product,such as cosmetics, detergents and paints.Siloxanes and hydrogen sulfide removal from biogas can be carried out by various methods (Ajhar et al., 2010); aim of the present work is to find a single practical andeconomic way to drastically and simultaneously reduce both hydrogen sulfide and the siloxanes concentration to less than 1 ppm. Some commercial activated carbons previously selected (Monteleoneet al., 2011) as being effective in hydrogen sulfide up taking have been tested in an adsorption measurement apparatus, by flowing both hydrogen sulphide and volatile siloxane (Decamethycyclopentasiloxane or D5) in a nitrogen stream,typically 25-300 ppm D5 over N2, through an clay minerals, Fe oxides and Silica; the adsorption process was analyzed by varying some experimental parameters (concentration, grain size, bed height). The best silica shows an adsorption capacity of 0.2 g D5 per gram of silica. The next thermo gravimetric analysis (TGA) confirms the capacity data obtained experimentally by the breakthrough curve tests.The capacity results depend on D5 and hydrogen sulphide concentrations. A regenerative silica process is then carried out byheating the silica bed up to 200 ° C and flushing out the adsorbed D5 and hydrogen sulphide samples in a nitrogen stream in athree step heating procedure up to 200 ° C. The adsorption capacity is observed to degrade after cyclingthe samples through several adsorption-desorption cycles.

  1. Transformation and destabilization of graphene oxide in reducing aqueous solutions containing sulfide.

    Science.gov (United States)

    Fu, Heyun; Qu, Xiaolei; Chen, Wei; Zhu, Dongqiang

    2014-12-01

    The colloidal stability of carbon nanomaterials is a key factor controlling their fate and bioavailability in natural aquatic systems. The authors report that graphene oxide nanoparticles could be destabilized in reducing aqueous solutions containing a low concentration (0.5 mM) of sulfide, a naturally occurring reductant. Spectroscopic characterization using combined X-ray photoelectron, Fourier-transform infrared, X-ray diffraction, and Raman analyses revealed that the surface oxygen-containing groups (mainly epoxy groups) of graphene oxide were significantly reduced after reacting with sodium sulfide. The destabilization of graphene oxide was likely caused by the enhanced surface hydrophobicity of the reduced graphene oxide, whereas electrostatic repulsion played a minimal role. Solution pH was found to affect both the deoxygenation process and the aggregation behavior of graphene oxide. Coexisting humic acid reduced the reaction efficiency and stabilized graphene oxide through steric hindrance. These findings suggest for the first time that the colloidal behavior of carbon nanomaterials might change drastically when they enter natural reducing environments containing sulfide such as anaerobic aquifers and sediments.

  2. Nitrogen release from forest soils containing sulfide-bearing sediments

    Science.gov (United States)

    Maileena Nieminen, Tiina; Merilä, Päivi; Ukonmaanaho, Liisa

    2014-05-01

    Soils containing sediments dominated by metal sulfides cause high acidity and release of heavy metals, when excavated or drained, as the aeration of these sediments causes formation of sulfuric acid. Consequent leaching of acidity and heavy metals can kill tree seedlings and animals such as fish, contaminate water, and corrode concrete and steel. These types of soils are called acid sulfate soils. Their metamorphic equivalents, such as sulfide rich black shales, pose a very similar risk of acidity and metal release to the environment. Until today the main focus in treatment of the acid sulfate soils has been to prevent acidification and metal toxicity to agricultural crop plants, and only limited attention has been paid to the environmental threat caused by the release of acidity and heavy metals to the surrounding water courses. Even less attention is paid on release of major nutrients, such as nitrogen, although these sediments are extremely rich in carbon and nitrogen and present a potentially high microbiological activity. In Europe, the largest cover of acid sulfate soils is found in coastal lowlands of Finland. Estimates of acid sulfate soils in agricultural use range from 1 300 to 3 000 km2, but the area in other land use classes, such as managed peatland forests, is presumably larger. In Finland, 49 500 km2 of peatlands have been drained for forestry, and most of these peatland forests will be at the regeneration stage within 10 to 30 years. As ditch network maintenance is often a prerequisite for a successful establishment of the following tree generation, the effects of maintenance operations on the quality of drainage water should be under special control in peatlands underlain by sulfide-bearing sediments. Therefore, identification of risk areas and effective prevention of acidity and metal release during drain maintenance related soil excavating are great challenges for forestry on coastal lowlands of Finland. The organic and inorganic nitrogen

  3. Hydrogen Sulfide as a "Double-Faced" Compound: One with Pro- and Antioxidant Effect.

    Science.gov (United States)

    Olas, B

    2017-01-01

    Hydrogen sulfide (H2S), like other gasotransmitters such as nitric oxide (NO(•)) and carbon monoxide (CO), acts as a signaling molecule in various biological systems. It may also regulate the oxidative stress observed in several diseases sometimes associated with changes of H2S concentration. This chapter describes the "double face" of hydrogen sulfide as both an antioxidant and a prooxidant in biological systems. One proposed mechanism by which H2S exerts its antioxidative effects is its ability to modulate the concentration of glutathione, which is a very important physiological antioxidant. This chapter discusses the interactions of H2S with various reactive oxygen species and reactive nitrogen species, including the superoxide radical anion [Formula: see text] , hydrogen peroxide (H2O2), and peroxynitrite anion (ONOO(-)), which is produced in a rapid reaction between [Formula: see text] and NO(•).

  4. Simulating pH and hydrogen sulfide in a distributed collection system

    DEFF Research Database (Denmark)

    Vollertsen, Jes; Le Guennec, Anne; Nielsen, Asbjørn Haaning

    2013-01-01

    A concept for modeling the pH in distributed sewer systems is presented. The concept is an extension of the existing sewer process model WATS, which simulates physical, chemical and biological processes in wastewater, biofilms, sediments, and sewer headspace, as well as water flow, gas flow...... was calibrated to the conveyance system of Tangier, Morocco, and was able to simulate the observed variation in pH as well as the observed levels of hydrogen sulfide in the network. For the sewer system of Tangier, the most important buffer system was the carbonate system, followed by ammonia and amino groups....... The pH decreased from 7.80 of fresh wastewater entering the nodes to 7.30 at the treatment plant. This decrease could be attributed to the processes of anaerobic fermentation and hydrogen sulfide formation in the network....

  5. Sulfide, the first inorganic substrate for human cells.

    Science.gov (United States)

    Goubern, Marc; Andriamihaja, Mireille; Nübel, Tobias; Blachier, François; Bouillaud, Frédéric

    2007-06-01

    Hydrogen sulfide (H2S) is produced inside the intestine and is known as a poison that inhibits cellular respiration at the level of cytochrome oxidase. However, sulfide is used as an energetic substrate by many photo- and chemoautotrophic bacteria and by animals such as the lugworm Arenicola marina. The concentrations of sulfide present in their habitats are comparable with those present in the human colon. Using permeabilized colonic cells to which sulfide was added by an infusion pump we show that the maximal respiratory rate of colonocyte mitochondria in presence of sulfide compares with that obtained with succinate or L-alpha-glycerophosphate. This oxidation is accompanied by mitochondrial energization. In contrast, other cell types not naturally exposed to high concentration of sulfide showed much lower oxidation rates. Mitochondria showed a very high affinity for sulfide that permits its use as an energetic substrate at low micromolar concentrations, hence, below the toxic level. However, if the supply of sulfide exceeds the oxidation rate, poisoning renders mitochondria inefficient and our data suggest that an anaerobic mechanism involving partial reversion of Krebs cycle already known in invertebrates takes place. In conclusion, this work provides additional and compelling evidence that sulfide is not only a toxic compound. According to our study, sulfide appears to be the first inorganic substrate for mammalian cells characterized thus far.

  6. Production of sulfur gases and carbon dioxide by synthetic weathering of crushed drill cores from the Santa Cruz porphyry copper deposit near Casa Grande, Pinal County, Arizona

    Science.gov (United States)

    Hinkle, M.E.; Ryder, J.L.; Sutley, S.J.; Botinelly, T.

    1990-01-01

    Samples of ground drill cores from the southern part of the Santa Cruz porphyry copper deposit, Casa Grande, Arizona, were oxidized in simulated weathering experiments. The samples were also separated into various mineral fractions and analyzed for contents of metals and sulfide minerals. The principal sulfide mineral present was pyrite. Gases produced in the weathering experiments were measured by gas chromatography. Carbon dioxide, oxygen, carbonyl sulfide, sulfur dioxide and carbon disulfide were found in the gases; no hydrogen sulfide, organic sulfides, or mercaptans were detected. Oxygen concentration was very important for production of the volatiles measured; in general, oxygen concentration was more important to gas production than were metallic element content, sulfide mineral content, or mineral fraction (oxide or sulfide) of the sample. The various volatile species also appeared to be interactive; some of the volatiles measured may have been formed through gas reactions. ?? 1990.

  7. Speciation of arsenic in sulfidic waters

    Directory of Open Access Journals (Sweden)

    Ford Robert G

    2003-03-01

    Full Text Available Formation constants for thioarsenite species have been determined in dilute solutions at 25°C, ΣH2S from 10-7.5 to 10-3.0 M, ΣAs from 10-5.6 to 10-4.8 M, and pH 7 and 10. The principal inorganic arsenic species in anoxic aquatic systems are arsenite, As(OH30, and a mononuclear thioarsenite with an S/As ratio of 3:1. Thioarsenic species with S/As ratios of 1 : 1,2 : 1, and 4 : 1 are lesser components in sulfidic solutions that might be encountered in natural aquatic environments. Thioarsenites dominate arsenic speciation at sulfide concentrations > 10-4.3 M at neutral pH. Conversion from neutral As(OH30 to anionic thioarsenite species may regulate the transport and fate of arsenic in sulfate-reducing environments by governing sorption and mineral precipitation reactions.

  8. Iron-sulfide redox flow batteries

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Guanguang; Yang, Zhenguo; Li, Liyu; Kim, Soowhan; Liu, Jun; Graff, Gordon L

    2016-06-14

    Iron-sulfide redox flow battery (RFB) systems can be advantageous for energy storage, particularly when the electrolytes have pH values greater than 6. Such systems can exhibit excellent energy conversion efficiency and stability and can utilize low-cost materials that are relatively safer and more environmentally friendly. One example of an iron-sulfide RFB is characterized by a positive electrolyte that comprises Fe(III) and/or Fe(II) in a positive electrolyte supporting solution, a negative electrolyte that comprises S.sup.2- and/or S in a negative electrolyte supporting solution, and a membrane, or a separator, that separates the positive electrolyte and electrode from the negative electrolyte and electrode.

  9. Oxidation of Reduced Sulfur Species: Carbonyl Sulfide

    DEFF Research Database (Denmark)

    Glarborg, Peter; Marshall, Paul

    2013-01-01

    A detailed chemical kinetic model for oxidation of carbonyl sulfide (OCS) has been developed, based on a critical evaluation of data from the literature. The mechanism has been validated against experimental results from batch reactors, flow reactors, and shock tubes. The model predicts satisfact......A detailed chemical kinetic model for oxidation of carbonyl sulfide (OCS) has been developed, based on a critical evaluation of data from the literature. The mechanism has been validated against experimental results from batch reactors, flow reactors, and shock tubes. The model predicts...... by the competition between chain‐branching and ‐propagating steps; modeling predictions are particularly sensitive to the branching fraction for the OCS + O reaction to form CO + SO or CO2 + S....

  10. Iron-sulfide redox flow batteries

    Science.gov (United States)

    Xia, Guan-Guang; Yang, Zhenguo; Li, Liyu; Kim, Soowhan; Liu, Jun; Graff, Gordon L

    2013-12-17

    Iron-sulfide redox flow battery (RFB) systems can be advantageous for energy storage, particularly when the electrolytes have pH values greater than 6. Such systems can exhibit excellent energy conversion efficiency and stability and can utilize low-cost materials that are relatively safer and more environmentally friendly. One example of an iron-sulfide RFB is characterized by a positive electrolyte that comprises Fe(III) and/or Fe(II) in a positive electrolyte supporting solution, a negative electrolyte that comprises S.sup.2- and/or S in a negative electrolyte supporting solution, and a membrane, or a separator, that separates the positive electrolyte and electrode from the negative electrolyte and electrode.

  11. Subsurface heaters with low sulfidation rates

    Energy Technology Data Exchange (ETDEWEB)

    John, Randy Carl; Vinegar, Harold J

    2013-12-10

    A system for heating a hydrocarbon containing formation includes a heater having an elongated ferromagnetic metal heater section. The heater is located in an opening in a formation. The heater section is configured to heat the hydrocarbon containing formation. The exposed ferromagnetic metal has a sulfidation rate that goes down with increasing temperature of the heater, when the heater is in a selected temperature range.

  12. Redetermination of piperidinium hydrogen sulfide structure

    Science.gov (United States)

    Andras, Maria T.; Hepp, Aloysius F.; Fanwick, Phillip E.; Duraj, Stan A.; Gordon, Edward M.

    1994-01-01

    The presence of adventitious water in a reaction between dicyclopentamethylene thiuram-disulfide (C5H10NCS2)(sub 2) and a picoline solution of tricyclopentadienyl indium(III) (C5H5)(sub 3). It resulted in the formation of piperidinium hydrogen sulfide (C5H13NS). The piperidinium hydrogen sulfide produced in this way was unambiguously characterized by X-ray crystallography. The structure determination showed that the piperidinium hydrogen sulfide crystal (MW = 119.23 g/mol) has an orthorhombic (Pbcm) unit cell whose parameters are: a = 9.818(2), b = 7.3720(1), c = 9.754(1) A, V = 706.0(3) A(exp 3), Z=4. D(sub chi) = 1.122 g cm(exp -3), Mo K(alpha) (lamda = 0.71073), mu= 3.36 cm(exp -1), F(000) = 264.0, T =293 K, R = 0.036 for 343 reflections with F(sub O)(sup 2) greater than 3 sigma (F(sub O)(sup 2)) and 65 variables. The compound consists of (C5H10NH2)(+) cations and (SH)(-) anions with both species residing on crystallographic mirror planes. N-H -- S hydrogen bonding contributes to the interconnection of neighboring piperidinium components of the compound.

  13. Air-water transfer of hydrogen sulfide

    DEFF Research Database (Denmark)

    Yongsiri, C.; Vollertsen, J.; Rasmussen, M. R.;

    2004-01-01

    experiments. By means of the overall mass–transfer coefficient (KLa), the transfer coefficient of hydrogen sulfide (KLaH2S), referring to total sulfide, was correlated to that of oxygen (KLaO2) (i.e., the reaeration coefficient). Results demonstrate that both turbulence and pH in the water phase play...... a significant role for KLaH2S. An exponential expression is a suitable representation for the relationship between KLaH2S and the Froude number at all pH values studied (4.5 to 8.0). Because of the dissociation of hydrogen sulfide, KLaH2S increased with decreasing pH at a constant turbulence level. Relative...... differences in KLaH2S at pH values between 4.5 and 8.0 became larger as the turbulence level increased, whereas those at pH between 4.5 and 7.0 did not statistically show any change. At constant pH, KLaH2S/KLaO2 was observed not to be dependent on the turbulence range studied. KLaH2S/KLaO2 ratio was 0...

  14. Sulfide scaling in low enthalpy geothermal environments; A survey

    Energy Technology Data Exchange (ETDEWEB)

    Criaud, A.; Fouillac, C. (Bureau de Recherches Geologiques et Minieres (BRGM), 45 - Orleans (France))

    1989-01-01

    A review of the sulfide scaling phenomena in low-temperature environments is presented. While high-temperature fluids tend to deposit metal sulfides because of their high concentrations of dissolved metals and variations of temperature, pressure and fluid chemistry, low temperature media are characterized by very low metal content but much higher dissolved sulfide. In the case of the goethermal wells of the Paris Basin, detailed studies demonstrate that the relatively large concentrations of chloride and dissolved sulfide are responsible for corrosion and consequent formation of iron sulfide scale composed of mackinawite, pyrite and pyrrhotite. The effects of the exploitation schemes are far less important than the corrosion of the casings. The low-enthalpy fluids that do not originate from sedimentary aquifers (such as in Iceland and Bulgaria), have a limited corrosion potential, and the thin sulfide film that appears may prevent the progress of corrosion.

  15. Oxidation and Precipitation of Sulfide in Sewer Networks

    DEFF Research Database (Denmark)

    Nielsen, A. H.

    calibrated and validated against field data. In the extension to the WATS model, sulfur transformations were described by six processes: 1. Sulfide production taking place in the biofilm and sediments covering the permanently wetted sewer walls; 2. Biological sulfide oxidation in the permanently wetted...... on oxidation and precipitation of sulfide, which are considered important processes in the sulfur cycle in wastewater and biofilms of sewer networks. Based on experimental studies, it was the objective to establish kinetics and stoichiometry of oxidation and precipitation of sulfide and to integrate...... the processes in an already existing sewer process model, thereby improving its capabilities for prediction of sulfide buildup in wastewater and atmosphere of sewer networks. Accordingly, efforts were made to develop experimental procedures for estimation of model parameters. Sulfide oxidation in both...

  16. Organization of the human mitochondrial hydrogen sulfide oxidation pathway.

    Science.gov (United States)

    Libiad, Marouane; Yadav, Pramod Kumar; Vitvitsky, Victor; Martinov, Michael; Banerjee, Ruma

    2014-11-07

    Sulfide oxidation is expected to play an important role in cellular switching between low steady-state intracellular hydrogen sulfide levels and the higher concentrations where the physiological effects are elicited. Yet despite its significance, fundamental questions regarding how the sulfide oxidation pathway is wired remain unanswered, and competing proposals exist that diverge at the very first step catalyzed by sulfide quinone oxidoreductase (SQR). We demonstrate that, in addition to sulfite, glutathione functions as a persulfide acceptor for human SQR and that rhodanese preferentially synthesizes rather than utilizes thiosulfate. The kinetic behavior of these enzymes provides compelling evidence for the flow of sulfide via SQR to glutathione persulfide, which is then partitioned to thiosulfate or sulfite. Kinetic simulations at physiologically relevant metabolite concentrations provide additional support for the organizational logic of the sulfide oxidation pathway in which glutathione persulfide is the first intermediate formed.

  17. Measurement of plasma hydrogen sulfide in vivo and in vitro

    OpenAIRE

    Shen, Xinggui; Pattillo, Christopher B.; Pardue, Sibile; Bir, Shyamal C.; Wang, Rui; Kevil, Christopher G.

    2011-01-01

    The gasotransmitter hydrogen sulfide is known to regulate multiple cellular functions during normal and pathophysiological states. However, a paucity of concise information exists regarding quantitative amounts of hydrogen sulfide involved in physiological and pathological responses. This is primarily due to disagreement among various methods employed to measure free hydrogen sulfide. In this article, we describe a very sensitive method of measuring the presence of H2S in plasma down to nanom...

  18. INVESTIGATION OF THIN FILM CADMIUM SULFIDE SOLAR CELLS.

    Science.gov (United States)

    SOLAR CELLS , *CADMIUM COMPOUNDS, FILMS, SULFIDES, VAPOR PLATING, VACUUM APPARATUS, SINGLE CRYSTALS, TITANIUM, COPPER COMPOUNDS, CHLORIDES, INDIUM, MOLYBDENUM, SILICON COMPOUNDS, MONOXIDES, SURFACE PROPERTIES, ENERGY CONVERSION.

  19. Hydrogen sulfide inhibits the renal fibrosis of obstructive nephropathy.

    Science.gov (United States)

    Song, Kai; Wang, Fen; Li, Qian; Shi, Yong-Bing; Zheng, Hui-Fen; Peng, Hanjing; Shen, Hua-Ying; Liu, Chun-Feng; Hu, Li-Fang

    2014-06-01

    Hydrogen sulfide has recently been found decreased in chronic kidney disease. Here we determined the effect and underlying mechanisms of hydrogen sulfide on a rat model of unilateral ureteral obstruction. Compared with normal rats, obstructive injury decreased the plasma hydrogen sulfide level. Cystathionine-β-synthase, a hydrogen sulfide-producing enzyme, was dramatically reduced in the ureteral obstructed kidney, but another enzyme cystathionine-γ-lyase was increased. A hydrogen sulfide donor (sodium hydrogen sulfide) inhibited renal fibrosis by attenuating the production of collagen, extracellular matrix, and the expression of α-smooth muscle actin. Meanwhile, the infiltration of macrophages and the expression of inflammatory cytokines including interleukin-1β, tumor necrosis factor-α, and monocyte chemoattractant protein-1 in the kidney were also decreased. In cultured kidney fibroblasts, a hydrogen sulfide donor inhibited the cell proliferation by reducing DNA synthesis and downregulating the expressions of proliferation-related proteins including proliferating cell nuclear antigen and c-Myc. Further, the hydrogen sulfide donor blocked the differentiation of quiescent renal fibroblasts to myofibroblasts by inhibiting the transforming growth factor-β1-Smad and mitogen-activated protein kinase signaling pathways. Thus, low doses of hydrogen sulfide or its releasing compounds may have therapeutic potentials in treating chronic kidney disease.

  20. Limitation of Sulfide Capacity Concept for Molten Slags

    Science.gov (United States)

    Jung, In-Ho; Moosavi-Khoonsari, Elmira

    2016-04-01

    The sulfide capacity concept has been widely used in pyrometallurgy to define sulfur removal capacities of slags. Typically, the sulfide capacity is considered to be a unique slag property depending only on temperature regardless of partial pressures of oxygen and sulfur. In the present study, it is demonstrated that sulfide capacities of slags in particular those of Na2O-containing slags can vary with partial pressures of oxygen and sulfur due to large solubility of sulfide in Na2O-containing slag systems.

  1. Influence of iron on sulfide inhibition in dark biohydrogen fermentation.

    Science.gov (United States)

    Dhar, Bipro Ranjan; Elbeshbishy, Elsayed; Nakhla, George

    2012-12-01

    Sulfide impact on biohydrogen production using dark fermentation of glucose at 37 °C was investigated. Dissolved sulfide (S(2-)) at a low concentration (25mg/L) increased biohydrogen production by 54% relative to the control (without iron addition). Whereas on initial dissolved S(2-) concentration of 500 mg/L significantly inhibited the biohydrogen production with total cumulative biohydrogen decreasing by 90% compared to the control (without iron addition). At sulfide concentrations of 500 mg S(2-)/L, addition of Fe(2+) at 3-4 times the theoretical requirement to precipitate 100% of the dissolved S(2-) entirely eliminated the inhibitory effect of sulfide.

  2. Effect of nitrite and nitrate on in situ sulfide production in an activated sludge immobilized agar gel film as determined by use of microelectrodes.

    Science.gov (United States)

    Okabe, Satoshi; Santegoeds, Cecilia M; De Beer, Dirk

    2003-03-01

    Microelectrode, fluorescence in situ hybridization (FISH), and denaturing gradient gel electrophoresis (DGGE) analyses were used to investigate the effect of nitrite and nitrate on in situ sulfide production in an activated sludge immobilized agar gel film. Microelectrode measurements of O(2), H(2)S, NO(3)(-), NO(2)(-), and pH revealed that the addition of NO(2)(-) and NO(3)(-) forced sulfate reduction zones deeper in the agar gel and significantly reduced the in situ sulfide production levels. The sulfate reduction zone was consequently separated from O(2) and NO(2)(-) or NO(3)(-) respiration zones with increasing the concentrations of NO(2)(-) and NO(3)(-). These NO(2)(-) and NO(3)(-) treatments had only a transient effect on sulfide production. The in situ sulfide production quickly recovered to the previous levels when NO(2)(-) and NO(3)(-) were removed. The PCR-DGGE and FISH analyses revealed that 2-day-continuous addition of 500 microM NO(3)(-) did not change the metabolically active sulfate-reducing bacterial (SRB) community. On the basis of these data, it could be concluded that the addition of NO(2)(-) and NO(3)(-) did not kill SRB, but induced the interspecies competition for common carbon source (i.e., acetate) between nitrate-reducing heterotrophic bacteria and SRB and enhanced the oxidation of the produced sulfide, which were main possible causes of the suppression of in situ sulfide production in the agar gel.

  3. MEASURING METAL SULFIDE COMPLEXES IN OXIC RIVER WATERS WITH SQUARE WAVE VOLTAMMETRY. (R825395)

    Science.gov (United States)

    A sulfide identification protocol was developed to quantify specific metal sulfides that could exist in river water. Using a series of acid additions, nitrogen purges, and voltammetric analyses, metal sulfides were identified and semiquantified in three specific gr...

  4. Toxicological analysis of 17 autopsy cases of hydrogen sulfide poisoning resulting from the inhalation of intentionally generated hydrogen sulfide gas.

    Science.gov (United States)

    Maebashi, Kyoko; Iwadate, Kimiharu; Sakai, Kentaro; Takatsu, Akihiro; Fukui, Kenji; Aoyagi, Miwako; Ochiai, Eriko; Nagai, Tomonori

    2011-04-15

    Although many cases of fatal hydrogen sulfide poisoning have been reported, in most of these cases, it resulted from the accidental inhalation of hydrogen sulfide gas. In recent years, we experienced 17 autopsy cases of fatal hydrogen sulfide poisoning due to the inhalation of intentionally generated hydrogen sulfide gas. In this study, the concentrations of sulfide and thiosulfate in blood, urine, cerebrospinal fluid and pleural effusion were examined using GC/MS. The sulfide concentrations were blood: 0.11-31.84, urine: 0.01-1.28, cerebrospinal fluid: 0.02-1.59 and pleural effusion: 2.00-8.59 (μg/ml), while the thiosulfate concentrations were blood: 0-0.648, urine: 0-2.669, cerebrospinal fluid: 0.004-0.314 and pleural effusion: 0.019-0.140 (μmol/ml). In previous reports, the blood concentration of thiosulfate was said to be higher than that of sulfide in hydrogen sulfide poisoning cases, although the latter was higher than the former in 8 of the 14 cases examined in this study. These results are believed to be strongly influenced by the atmospheric concentration of hydrogen sulfide the victims were exposed to and the time interval between exposure and death.

  5. Synthesis and Antiproliferative Activities of Benzimidazole-Based Sulfide and Sulfoxide Derivatives.

    Science.gov (United States)

    Gaballah, Samir T; El-Nezhawy, Ahmed O H; Amer, Hassan; Ali, Mamdouh Moawad; Mahmoud, Abeer Essam El-Din; Hofinger-Horvath, Andreas

    2016-01-01

    The design, synthesis, and in vitro antiproliferative activity of a novel series of sulfide (4a-i) and sulfoxide (5a-h) derivatives of benzimidazole, in which different aromatic and heteroaromatic acetamides are linked to benzimidazole via sulfide (4a-i) and sulfoxide (5a-h) linker, are reported and the structure-activity relationship is discussed. The new derivatives were prepared by coupling 2-(mercaptomethyl)benzimidazole with 2-bromo-N-(substituted) acetamides in dry acetone in the presence of anhydrous potassium carbonate. With very few exceptions, all of the synthesized compounds showed varying antiprolific activities against HepG2, MCF-7, and A549 cell lines. Compound 5a was very similar in potency to doxorubicin as an anticancer drug, with IC50 values 4.1 ± 0.5, 4.1 ± 0.5, and 5.0 ± 0.6 µg/mL versus 4.2 ± 0.5, 4.9 ± 0.6, and 6.1 ± 0.6 µg/mL against HepG2, MCF-7, and A549 cell lines, respectively. In contrast, none of the compounds showed activity against human prostate PC3 cancer cells. Additionally, the sulfoxide derivatives were more potent than the corresponding sulfides.

  6. Resonant photoactivation of cadmium sulfide and its effect on the surface chemical activity

    Science.gov (United States)

    Giberti, Alessio; Fabbri, Barbara; Gaiardo, Andrea; Guidi, Vincenzo; Malagù, Cesare

    2014-06-01

    Photo-enhanced surface chemical activity of cadmium sulfide gives rise to a wide class of surface-dependent phenomena, such as heterogeneous photocatalysis, chemoresistivity, and chemiluminescence, which have several technological and scientific applications. In this work, the photochemical properties of nanostructured cadmium sulfide films are investigated by means of electrical conductance measurements in controlled atmosphere, while irradiated by light of wavelengths ranging from 400 to 645 nm. Chemisorption of benzene, carbon monoxide, methane, ethanol, and hydrogen sulfide onto CdS surface has been analyzed as a function of the wavelength, in a gas concentration range of the order of parts per million. It resulted that the increase of photoconductance with gas adsorption is resonant with the bandgap energy. It turns out that this resonant enhancement of the surface chemical activity can be of advantage for all the optical and chemical mechanisms that depend upon it. An interpretation of these results, in terms of electronic optical transitions and Fermi level shift induced by light, is proposed.

  7. Combining experiment and theory to elucidate the role of supercritical water in sulfide decomposition.

    Science.gov (United States)

    Kida, Yuko; Class, Caleb A; Concepcion, Anthony J; Timko, Michael T; Green, William H

    2014-05-28

    The cleavage of C-S linkages plays a key role in fuel processing and organic geochemistry. Water is known to affect these processes, and several hypotheses have been proposed, but the mechanism has been elusive. Here we use both experiment and theory to demonstrate that supercritical water reacts with intermediates formed during alkyl sulfide decomposition. During hexyl sulfide decomposition in supercritical water, pentane and CO + CO2 were detected in addition to the expected six carbon products. A multi-step reaction sequence for hexyl sulfide reacting with supercritical water is proposed which explains the surprising products, and quantum chemical calculations provide quantitative rates that support the proposed mechanism. The key sequence is cleavage of one C-S bond to form a thioaldehyde via radical reactions, followed by a pericyclic addition of water to the C[double bond, length as m-dash]S bond to form a geminal mercaptoalcohol. The mercaptoalcohol decomposes into an aldehyde and H2S either directly or via a water-catalyzed 6-membered ring transition state. The aldehyde quickly decomposes into CO plus pentane by radical reactions. The time is ripe for quantitative modelling of organosulfur reaction kinetics based on modern quantum chemistry.

  8. One-Step Electrodeposited Nickel Cobalt Sulfide Nanosheet Arrays for High-Performance Asymmetric Supercapacitors

    KAUST Repository

    Chen, Wei

    2014-09-23

    A facile one-step electrodeposition method is developed to prepare ternary nickel cobalt sulfide interconnected nanosheet arrays on conductive carbon substrates as electrodes for supercapacitors, resulting in exceptional energy storage performance. Taking advantages of the highly conductive, mesoporous nature of the nanosheets and open framework of the three-dimensional nanoarchitectures, the ternary sulfide electrodes exhibit high specific capacitance (1418 F g(-1) at 5 A g(-1) and 1285 F g(-1) at 100 A g(-1)) with excellent rate capability. An asymmetric supercapacitor fabricated by the ternary sulfide nanosheet arrays as positive electrode and porous graphene film as negative electrode demonstrates outstanding electrochemical performance for practical energy storage applications. Our asymmetric supercapacitors show a high energy density of 60 Wh kg(-1) at a power density of 1.8 kW kg(-1). Even when charging the cell within 4.5 s, the energy density is still as high as 33 Wh kg(-1) at an outstanding power density of 28.8 kW kg(-1) with robust long-term cycling stability up to 50 000 cycles.

  9. Effects of humic substances on precipitation and aggregation of zinc sulfide nanoparticles

    Science.gov (United States)

    Deonarine, A.; Lau, B.L.T.; Aiken, G.R.; Ryan, J.N.; Hsu-Kim, H.

    2011-01-01

    Nanoparticulate metal sulfides such as ZnS can influence the transport and bioavailability of pollutant metals in anaerobic environments. The aim of this work was to investigate how the composition of dissolved natural organic matter (NOM) influences the stability of zinc sulfide nanoparticles as they nucleate and aggregate in water with dissolved NOM. We compared NOM fractions that were isolated from several surface waters and represented a range of characteristics including molecular weight, type of carbon, and ligand density. Dynamic light scattering was employed to monitor the growth and aggregation of Zn-S-NOM nanoparticles in supersaturated solutions containing dissolved aquatic humic substances. The NOM was observed to reduce particle growth rates, depending on solution variables such as type and concentration of NOM, monovalent electrolyte concentration, and pH. The rates of growth increased with increasing ionic strength, indicating that observed growth rates primarily represented aggregation of charged Zn-S-NOM particles. Furthermore, the observed rates decreased with increasing molecular weight and aromatic content of the NOM fractions, while carboxylate and reduced sulfur content had little effect. Differences between NOM were likely due to properties that increased electrosteric hindrances for aggregation. Overall, results of this study suggest that the composition and source of NOM are key factors that contribute to the stabilization and persistence of zinc sulfide nanoparticles in the aquatic environment. ?? 2011 American Chemical Society.

  10. Effects of humic substance on precipitation and aggregation of zinc sulfide nanoparticles

    Science.gov (United States)

    Deonarine, Amrika; Lau, Boris L.T.; Aiken, George R.; Ryan, Joseph N.; Hsu-Kim, Heileen

    2011-01-01

    Nanoparticulate metal sulfides such as ZnS can influence the transport and bioavailability of pollutant metals in anaerobic environments. The aim of this work was to investigate how the composition of dissolved natural organic matter (NOM) influences the stability of zinc sulfide nanoparticles as they nucleate and aggregate in water with dissolved NOM. We compared NOM fractions that were isolated from several surface waters and represented a range of characteristics including molecular weight, type of carbon, and ligand density. Dynamic light scattering was employed to monitor the growth and aggregation of Zn-S-NOM nanoparticles in supersaturated solutions containing dissolved aquatic humic substances. The NOM was observed to reduce particle growth rates, depending on solution variables such as type and concentration of NOM, monovalent electrolyte concentration, and pH. The rates of growth increased with increasing ionic strength, indicating that observed growth rates primarily represented aggregation of charged Zn-S-NOM particles. Furthermore, the observed rates decreased with increasing molecular weight and aromatic content of the NOM fractions, while carboxylate and reduced sulfur content had little effect. Differences between NOM were likely due to properties that increased electrosteric hindrances for aggregation. Overall, results of this study suggest that the composition and source of NOM are key factors that contribute to the stabilization and persistence of zinc sulfide nanoparticles in the aquatic environment.

  11. 12 WEEK EXPOSURE TO CARBONYL SULFIDE PRODUCES BRAIN LESIONS AND CHANGES IN BRAINSTEM AUDITORY (BAER) AND SOMATOSENAORY (SEP) EVOKED POTENTIALS IN FISCHER 344N RATS

    Science.gov (United States)

    Carbonyl sulfide (COS) is a chemical intermediate in the production of pesticides and herbicides, is a metabolite of carbon disulfide, is produced by the combustion of organic material, and is found occurring in nature. COS was included in a Toxic Substances Control Act request f...

  12. Modeling Sulfides, pH and Hydrogen Sulfide Gas in the Sewers of San Francisco.

    Science.gov (United States)

    Vollertsen, Jes; Revilla, Nohemy; Hvitved-Jacobsen, Thorkild; Nielsen, Asbjørn Haaning

    2015-11-01

    An extensive measuring campaign targeted on sewer odor problems was undertaken in San Francisco. It was assessed whether a conceptual sewer process model could reproduce the measured concentrations of total sulfide in the wastewater and H2S gas in the sewer atmosphere, and to which degree such simulations have potential for further improving odor and sulfide management. The campaign covered measurement of wastewater sulfide by grab sampling and diurnal sampling, and H2S gas in the sewer atmosphere was logged. The tested model was based on the Wastewater Aerobic/Anaerobic Transformations in Sewers (WATS) sewer process concept, which never had been calibrated to such an extensive dataset. The study showed that the model was capable of reproducing the general levels of wastewater sulfide, wastewater pH, and sewer H2S gas. It could also reproduce the general variability of these parameters, albeit with some uncertainty. It was concluded that the model could be applied for the purpose in mind.

  13. The Effects of Acute Hydrogen Sulfide Poisoning on Cytochrome P450 Isoforms Activity in Rats

    OpenAIRE

    Xianqin Wang; Mengchun Chen; Xinxin Chen; Jianshe Ma; Congcong Wen; Jianchun Pan; Lufeng Hu; Guanyang Lin

    2014-01-01

    Hydrogen sulfide (H2S) is the second leading cause of toxin related death (after carbon monoxide) in the workplace. H2S is absorbed by the upper respiratory tract mucosa, and it causes histotoxic hypoxemia and respiratory depression. Cocktail method was used to evaluate the influences of acute H2S poisoning on the activities of cytochrome P450 isoforms CYP2B6, CYP2D6, CYP3A4, CYP1A2, CYP2C19, and CYP2C9, which were reflected by the changes of pharmacokinetic parameters of six specific probe d...

  14. Well-dispersed cadmium sulfide prepared in the presence of laponite by microwave irradiation

    Science.gov (United States)

    Han, Zhaohui; Yang, Qing; Shi, Jeffrey; Lu, G. Q.; Lewis, Simon W.

    2008-05-01

    The reactions of cadmium chloride and various sulfur sources in the suspension of laponite produced CdS nanoparticles. Laponite was used to help keep good dispersion of the sulfide particles and it also facilitated the formation of the product by providing a basic environment when carbon disulfide was used as a source of sulfur in the reaction. The amount of laponite used in the preparation, heating rate and reaction temperature were tested for their effect on result. Different sulfur source materials were used for the preparation, and reactions involved in the preparation were discussed. The varied reaction conditions produced CdS particles with varied shape and size, and in good dispersion.

  15. (Uncertain) Carbonyl Sulfide Plant Fluxes Spatially Constrain (Even More Uncertain) CO2 GPP

    Science.gov (United States)

    Hilton, T. W.; Whelan, M.; Kulkarni, S.; Zumkehr, A. L.; Berry, J. A.; Campbell, J. E.

    2015-12-01

    With predictions of future terrestrial carbon dioxide (CO2)gross primary productivity (GPP) remaining stubbornly uncertain,ecosystem carbonyl sulfide (COS) fluxes provide an independent source ofinformation that may be able to reduce that uncertainty. Several openquestions must be addressed before COS may be applied widely as a GPPtracer. Here we employ an atmospheric chemistry and transport model(STEM) and airborne atmospheric COS concentration observations todemonstrate that COS plant uptake spatially constrains CO2 GPP even whenaccounting for soil COS flux uncertainty and COS leaf-scale relativeuptake variability and uncertainty.

  16. Mercury Sulfide Dimorphism in Thioarsenate Glasses

    OpenAIRE

    KASSEM, Mohammad; Sokolov, Anton; Cuisset, Arnaud,; Usuki, Takeshi; Khaoulani, Sohayb; Masselin, Pascal; Le Coq, David,; Feygenson, M.; Benmore, C. J.; Hannon, Alex,; Neuefeind, J. C.; Bychkov, Eugene

    2016-01-01

    International audience; Crystalline mercury sulfide exists in two drastically different polymorphic forms in different domains of the P,T-diagram: red chain-like insulator α-HgS, stable below 344 °C, and black tetrahedral narrow-band semiconductor β-HgS, stable at higher temperatures. Using pulsed neutron and high-energy X-ray diffraction, we show that these two mercury bonding pattern are present simultaneously in mercury thioarsenate glasses HgS-As2S3. The population and interconnectivity o...

  17. The impact of electrogenic sulfide oxidation on elemental cycling and solute fluxes in coastal sediment

    Science.gov (United States)

    Rao, Alexandra M. F.; Malkin, Sairah Y.; Hidalgo-Martinez, Silvia; Meysman, Filip J. R.

    2016-01-01

    Filamentous sulfide oxidizing cable bacteria are capable of linking the oxidation of free sulfide in deep anoxic layers of marine sediments to the reduction of oxygen or nitrate in surface sediments by conducting electrons over centimeter-scale distances. Previous studies have shown that this newly discovered microbial process, referred to as electrogenic sulfide oxidation (e-SOx), may alter elemental cycling in sediments, but the nature and rates of the resulting biogeochemical transformations and their influence on benthic-pelagic coupling remain largely unknown. Here we quantify changes in sediment geochemistry and solute fluxes at the sediment-water interface as e-SOx develops and declines over time in laboratory incubations of organic-rich sediments from a seasonally hypoxic coastal basin (Marine Lake Grevelingen, The Netherlands). Our results show that e-SOx enhanced sediment O2 consumption and acidified subsurface sediment, resulting in the dissolution of calcium carbonate and iron sulfide minerals in deeper sediment horizons and the associated accumulation of dissolved iron, manganese, and calcium in porewater. Remobilized Fe diffusing upward was reoxidized at the sediment-water interface, producing an amorphous Fe oxide crust, while dissolved Fe diffusing downward was reprecipitated in the form of FeS as it encountered the free sulfide horizon. The development of e-SOx enhanced the diffusive release of dissolved Mn at the sediment-water interface, capped the phosphate efflux, generated a buildup of organic matter in surface sediments, and strongly stimulated the release of alkalinity from the sediment. About 75% of this alkalinity production was associated with net CaCO3 dissolution, while the remaining 25% was attributed to a pumping mechanism that transfers alkalinity from anodic H2S oxidation (an alkalinity sink) in deeper sediments to cathodic O2 reduction (an alkalinity source) near the sediment-water interface. The resulting sediment alkalinity

  18. Diurnal changes in pore water sulfide concentrations in the seagrass Thalassia testudinum beds: the effects of seagrasses on sulfide dynamics.

    Science.gov (United States)

    Lee; Dunton

    2000-12-20

    The dynamics of the seagrass-sulfide interaction were examined in relation to diel changes in sediment pore water sulfide concentrations in Thalassia testudinum beds and adjacent bare areas in Corpus Christi Bay and lower Laguna Madre, Texas, USA, during July 1996. Pore water sulfide concentrations in seagrass beds were significantly higher than in adjacent bare areas and showed strong diurnal variations; levels significantly decreased during mid-day at shallow sediment depths (0-10 cm) containing high below-ground tissue biomass and surface area. In contrast, diurnal variations in sediment sulfide concentrations were absent in adjacent bare patches, and at deeper (>10 cm) sediment depths characterized by low below-ground plant biomass or when the grasses were experimentally shaded. These observations suggest that the mid-day depressions in sulfide levels are linked to the transport of photosynthetically produced oxygen to seagrass below-ground tissues that fuels sediment sulfide oxidation. Lower sulfide concentrations in bare areas are likely a result of low sulfate reduction rates due to low organic matter available for remineralization. Further, high reoxidation rates due to rapid exchange between anoxic pore water and oxic overlying water are probably stimulated in bare areas by higher current velocity on the sediment surface than in seagrass beds. The dynamics of pore water sulfides in seagrass beds suggest no toxic sulfide intrusion into below-ground tissues during photosynthetic periods and demonstrate that the sediment chemical environment is considerably modified by seagrasses. The reduced sediment sulfide levels in seagrass beds during photosynthetic periods will enhance seagrass production through reduced sulfide toxicity to seagrasses and sediment microorganisms related to the nutrient cycling.

  19. Recent findings on sinks for sulfide in gravity sewer networks

    DEFF Research Database (Denmark)

    Nielsen, Asbjørn Haaning; Hvitved-Jacobsen, Thorkild; Vollertsen, Jes

    2006-01-01

    summarizes this newly obtained knowledge and emphasizes important implications of the findings. Model simulations of the in-sewer processes important for the sulfur cycle showed that sulfide oxidation in the wetted biofilm is typically the most important sink for dissolved sulfide in gravity sewers. However...

  20. Synthesis, Deposition, and Microstructure Development of Thin Films Formed by Sulfidation and Selenization of Copper Zinc Tin Sulfide Nanocrystals

    Science.gov (United States)

    Chernomordik, Boris David

    required to grow the same size grains on quartz (700 °C and 500 Torr). Moreover, carbon is removed by volatilization from films where normal crystal growth is fast. There are significant differences in the chemistry and in the thermodynamics involved during selenization and sulfidation of CZTS colloidal nanocrystal coatings to form CZTSSe or CZTS thin films, respectively. To understand these differences, the roles of vapor pressure, annealing temperature, and heating rate in the formation of different microstructures of CZTSSe films were investigated. Selenization produced a bi-layer microstructure where a large CZTSSe-crystal layer grew on top of a nanocrystalline carbon-rich bottom layer. Differences in the chemistry of carbon and selenium and that of carbon and sulfur account for this segregation of carbon during selenization. For example, CSe 2 and CS2, both volatile species, may form as a result of chalcogen interactions with carbon during annealing. Unlike CS2, however, CSe2 may readily polymerize at room temperature and one atmosphere. Carbon segregation may be occurring only during selenization due to the formation of a Cu-Se polymer [i.e., (CSe 2-x)] within the nanocrystal film. The (CSe2-x) inhibits sintering of nanocrystals in the bottom layer. Additionally, a fast heating rate results in temperature variations that lead to transient condensation of selenium on the film. This is observed only during selenization because the equilibrium vapor pressure of selenium is lower than that of sulfur. The presence of liquid selenium during sintering accelerates coarsening and densification of the normal crystal layer (no abnormal crystal layer) by liquid phase sintering. Carbon segregation does not occur where liquid selenium was present.

  1. Tropical sources and sinks of carbonyl sulfide observed from space

    Science.gov (United States)

    Glatthor, Norbert; Höpfner, Michael; Baker, Ian T.; Berry, Joe; Campbell, Elliott; Kawa, Stephan R.; Krysztofiak, Gisele; Sinnhuber, Björn-Martin; Stiller, Gabriele; Stinecipher, Jim; von Clarmann, Thomas

    2016-04-01

    According to current budget estimations the seasonal variation of carbonyl sulfide (COS) is governed by oceanic release and vegetation uptake. Its assimilation by plants is assumed to be similar to the photosynthetic uptake of CO2 but, contrary to the latter process, to be irreversible. Therefore COS has been suggested as co-tracer of the carbon cycle. Observations of COS, however, are sparse, especially in tropical regions. We use the comprehensive data set of spaceborne measurements of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) to analyze its global distribution. Two major features are observed in the tropical upper troposphere around 250 hPa: enhanced amounts over the western Pacific and the Maritime Continent, peaking around 550 pptv in boreal summer, and a seasonally varying depletion of COS extending from tropical South America to Africa. The large-scale COS depletion, which in austral summer amounts up to -40 pptv as compared to the rest of the respective latitude band, has not been observed before and reveals the seasonality of COS uptake through tropical vegetation. The observations can only be reproduced by global models, when a large vegetation uptake and a corresponding increase in oceanic emissions as proposed in several recent publications is assumed.

  2. Removal of Hydrogen Sulfide Gas using Biofiltration - a Review

    Directory of Open Access Journals (Sweden)

    Cheerawit RATTANAPAN

    2012-03-01

    Full Text Available Hydrogen sulfide (H2S is extremely toxic to living organisms and plants. H2S gas contamination may be treated by both chemical and physical methods but they have high capital costs, demand large energy inputs and result in the generation of secondary hazardous wastes. Biofiltration, a biological technique, has significant economic advantages over other air pollution control technologies. Biofiltration is a process by which contaminated gases pass through the biofilter and pollutants are transported into the biofilm where they are utilized by microbes as a carbon source, an energy source. Thiobacillus sp. is the most frequently used microbial species in H2S biofiltration and can degrade H2S for energy and produce sulfate or sulfuric acid. Moreover, media selection for biofiltration (combing both natural and synthetic media is an important step towards the development of a successful biofiltration operation. In addition, the optimization parameters of a biofiltration operation are found. First, optimal moisture content may vary from 20 to 60 wt%. Second, most microbial growths occur near neutral pH and wide deviation from these levels will impact the efficiency of the biofiltration. Third, the optimum temperature of biofiltration is near the optimum temperature for microbial inoculation based on removal efficiency. Finally, because nutrient supply is less critical as H2S removal requires few nutrients, commercial fertilizer or secondary effluent from wastewater treatment plants can be used for humid and nutrient supply. Many biofiltrations are designed for H2S control.Graphical abstract

  3. Physiological Importance of Hydrogen Sulfide: Emerging Potent Neuroprotector and Neuromodulator

    Science.gov (United States)

    Chung, Hyung-Joo

    2016-01-01

    Hydrogen sulfide (H2S) is an emerging neuromodulator that is considered to be a gasotransmitter similar to nitrogen oxide (NO) and carbon monoxide (CO). H2S exerts universal cytoprotective effects and acts as a defense mechanism in organisms ranging from bacteria to mammals. It is produced by the enzymes cystathionine β-synthase (CBS), cystathionine ϒ-lyase (CSE), 3-mercaptopyruvate sulfurtransferase (MST), and D-amino acid oxidase (DAO), which are also involved in tissue-specific biochemical pathways for H2S production in the human body. H2S exerts a wide range of pathological and physiological functions in the human body, from endocrine system and cellular longevity to hepatic protection and kidney function. Previous studies have shown that H2S plays important roles in peripheral nerve regeneration and degeneration and has significant value during Schwann cell dedifferentiation and proliferation but it is also associated with axonal degradation and the remyelination of Schwann cells. To date, physiological and toxic levels of H2S in the human body remain unclear and most of the mechanisms of action underlying the effects of H2S have yet to be fully elucidated. The primary purpose of this review was to provide an overview of the role of H2S in the human body and to describe its beneficial effects. PMID:27413423

  4. Carbonyl sulfide uptake and chloroform emissions from an Arctic site

    Science.gov (United States)

    Elkins, J. W.; Dutton, G. S.; Montzka, S. A.; Nance, J. D.; Hall, B. D.; Thoning, K. W.; Miller, J. B.; White, J.; Vaugh, B.; Manning, A.

    2008-12-01

    The Arctic Region is most sensitive to future climate change. Quantifying emissions and sinks of many important biogenic trace gases there may become important indicators of potential climate feedback. Once snowmelt at Pt. Barrow, Alaska (77o N) occurs, ground cover is exposed by sunlight and higher temperatures, then photosynthesis starts up. Peaks of chloroform (CHCl3) appear throughout the summer from southerly-based air masses based over northern Alaska and northwest Canada. Carbonyl sulfide (COS) undergoes uptake throughout the summer season through the same enzymes that uptake carbon dioxide (CO2). We will calculate the footprint of emissions of CHCl3 and uptake of COS using high frequency in situ observations, and the NAME and FLEXPART models. Previous studies show a large source of CHCl3 (8% of the total budget) may be coming from soils in high latitude pine forests. We will examine emissions of CHCl3 to see whether or not they are coming from the tundra just south of Pt. Barrow. We will identify the regions for uptake of COS and CO2 from the footprint generated from the models.

  5. Influence of Water Salinity on Air Purification from Hydrogen Sulfide

    Directory of Open Access Journals (Sweden)

    Leybovych L.I.

    2015-12-01

    Full Text Available Mathematical modeling of «sliding» water drop motion in the air flow was performed in software package FlowVision. The result of mathematical modeling of water motion in a droplet with diameter 100 microns at the «sliding» velocity of 15 m/s is shown. It is established that hydrogen sulfide oxidation occurs at the surface of phases contact. The schematic diagram of the experimental setup for studying air purification from hydrogen sulfide is shown. The results of the experimental research of hydrogen sulfide oxidation by tap and distilled water are presented. The dependence determining the share of hydrogen sulfide oxidized at the surface of phases contact from the dimensionless initial concentration of hydrogen sulfide in the air has been obtained.

  6. Mechanical properties of gutta-percha sulfide modified asphalt

    Science.gov (United States)

    Zou, X. Y.; Gu, X. Y.; Wang, X. W.

    2017-01-01

    Gutta-percha is the isomer of caoutchouc and can be used to enhance the performance of asphalt. In this paper, the produce proceedings of gutta-percha sulfide and gutta-percha sulfide modified asphalt are introduced. The performance indices of gutta-percha sulfide modified asphalt samples with different proportions are examined based on laboratory tests and the optimum ratio of gutta-percha and sulfur is decided.The micromechanism, temperature sensitivity, high and low temperature properties and viscoelasticity of the polymer modified asphalt are analyzed to discuss the modified mechanism and to decide the optimal polymer content. Low temperature bending tests are carried out to verify the low temperature performance of gutta-percha sulfide modified asphalt mixture. Research results showed that gutta-percha sulfide modified asphalt has good low temperature performance and a promising application prospect in the cold regions.

  7. Sulindac Sulfide, but Not Sulindac Sulfone, Inhibits Colorectal Cancer Growth

    Directory of Open Access Journals (Sweden)

    Christopher S. Williams

    1999-06-01

    Full Text Available Sulindac sulfide, a metabolite of the nonsteroidal antiinflammatory drug (NSAID sulindac sulfoxide, is effective at reducing tumor burden in both familial adenomatous polyposis patients and in animals with colorectal cancer. Another sulindac sulfoxide metabolite, sulindac sulfone, has been reported to have antitumor properties without inhibiting cyclooxygenase activity. Here we report the effect of sulindac sulfone treatment on the growth of colorectal carcinoma cells. We observed that sulindac sulfide or sulfone treatment of HCA-7 cells led to inhibition of prostaglandin E2 production. Both sulindac sulfide and sulfone inhibited HCA-7 and HCT-116 cell growth in vitro. Sulindac sulfone had no effect on the growth of either HCA-7 or HCT-116 xenografts, whereas the sulfide derivative inhibited HCA-7 growth in vivo. Both sulindac sulfide and sulfone inhibited colon carcinoma cell growth and prostaglandin production in vitro, but sulindac sulfone had no effect on the growth of colon cancer cell xenografts in nude mice.

  8. Hierarchical Architecturing for Layered Thermoelectric Sulfides and Chalcogenides

    Directory of Open Access Journals (Sweden)

    Priyanka Jood

    2015-03-01

    Full Text Available Sulfides are promising candidates for environment-friendly and cost-effective thermoelectric materials. In this article, we review the recent progress in all-length-scale hierarchical architecturing for sulfides and chalcogenides, highlighting the key strategies used to enhance their thermoelectric performance. We primarily focus on TiS2-based layered sulfides, misfit layered sulfides, homologous chalcogenides, accordion-like layered Sn chalcogenides, and thermoelectric minerals. CS2 sulfurization is an appropriate method for preparing sulfide thermoelectric materials. At the atomic scale, the intercalation of guest atoms/layers into host crystal layers, crystal-structural evolution enabled by the homologous series, and low-energy atomic vibration effectively scatter phonons, resulting in a reduced lattice thermal conductivity. At the nanoscale, stacking faults further reduce the lattice thermal conductivity. At the microscale, the highly oriented microtexture allows high carrier mobility in the in-plane direction, leading to a high thermoelectric power factor.

  9. Effect of palladium on sulfide tarnishing of noble metal alloys.

    Science.gov (United States)

    Suoninen, E; Herø, H; Minni, E

    1985-10-01

    Electron spectroscopic studies of Au-Ag-Cu alloys of the type used for dental castings show that small additions (less than or equal to 3 wt%) of palladium reduce essentially the thickness of the sulfide layer formed on surfaces of samples treated in aqueous Na2S solutions. Relative to silver, palladium does not enrich in the sulfide, but statistically significant enrichment is found immediately below the sulfide layer. This enrichment probably takes place during the exposure of the substrate surface to atmosphere before the sulfiding treatment. The mechanism of the impeding effect of palladium on sulfiding is assumed to be a decrease in diffusion from the bulk alloy to the surface due to the enriched layer. The effect cannot be explained by changes in the electronic structure of the alloy due to palladium alloying.

  10. Metagenome-based metabolic reconstruction reveals the ecophysiological function of Epsilonproteobacteria in a hydrocarbon-contaminated sulfidic aquifer

    Directory of Open Access Journals (Sweden)

    Andreas Hardy Keller

    2015-12-01

    Full Text Available The population genome of an uncultured bacterium assigned to the Campylobacterales (Epsilonproteobacteria was reconstructed from a metagenome dataset obtained by whole-genome shotgun pyrosequencing. Genomic DNA was extracted from a sulfate-reducing, m-xylene-mineralizing enrichment culture isolated from groundwater of a benzene-contaminated sulfidic aquifer. The identical epsilonproteobacterial phylotype has previously been detected in toluene- or benzene-mineralizing, sulfate-reducing consortia enriched from the same site. Previous stable isotope probing experiments with 13C6-labeled benzene suggested that this phylotype assimilates benzene-derived carbon in a syntrophic benzene-mineralizing consortium that uses sulfate as terminal electron acceptor. However, the type of energy metabolism and the ecophysiological function of this epsilonproteobacterium within aromatic hydrocarbon-degrading consortia and in the sulfidic aquifer are poorly understood.Annotation of the epsilonproteobacterial population genome suggests that the bacterium plays a key role in sulfur cycling as indicated by the presence of a sqr gene encoding a sulfide quinone oxidoreductase and psr genes encoding a polysulfide reductase. It may gain energy by using sulfide or hydrogen/formate as electron donors. Polysulfide, fumarate, as well as oxygen are potential electron acceptors. Auto- or mixotrophic carbon metabolism seems plausible since a complete reductive citric acid cycle was detected. Thus the bacterium can thrive in pristine groundwater as well as in hydrocarbon-contaminated aquifers. In hydrocarbon-contaminated sulfidic habitats, the epsilonproteobacterium may generate energy by coupling the oxidation of hydrogen or formate and highly abundant sulfide with the reduction of fumarate and/or polysulfide, accompanied by efficient assimilation of acetate produced during fermentation or incomplete oxidation of hydrocarbons. The highly efficient assimilation of acetate was

  11. Metagenome-Based Metabolic Reconstruction Reveals the Ecophysiological Function of Epsilonproteobacteria in a Hydrocarbon-Contaminated Sulfidic Aquifer

    Science.gov (United States)

    Keller, Andreas H.; Schleinitz, Kathleen M.; Starke, Robert; Bertilsson, Stefan; Vogt, Carsten; Kleinsteuber, Sabine

    2015-01-01

    The population genome of an uncultured bacterium assigned to the Campylobacterales (Epsilonproteobacteria) was reconstructed from a metagenome dataset obtained by whole-genome shotgun pyrosequencing. Genomic DNA was extracted from a sulfate-reducing, m-xylene-mineralizing enrichment culture isolated from groundwater of a benzene-contaminated sulfidic aquifer. The identical epsilonproteobacterial phylotype has previously been detected in toluene- or benzene-mineralizing, sulfate-reducing consortia enriched from the same site. Previous stable isotope probing (SIP) experiments with 13C6-labeled benzene suggested that this phylotype assimilates benzene-derived carbon in a syntrophic benzene-mineralizing consortium that uses sulfate as terminal electron acceptor. However, the type of energy metabolism and the ecophysiological function of this epsilonproteobacterium within aromatic hydrocarbon-degrading consortia and in the sulfidic aquifer are poorly understood. Annotation of the epsilonproteobacterial population genome suggests that the bacterium plays a key role in sulfur cycling as indicated by the presence of an sqr gene encoding a sulfide quinone oxidoreductase and psr genes encoding a polysulfide reductase. It may gain energy by using sulfide or hydrogen/formate as electron donors. Polysulfide, fumarate, as well as oxygen are potential electron acceptors. Auto- or mixotrophic carbon metabolism seems plausible since a complete reductive citric acid cycle was detected. Thus the bacterium can thrive in pristine groundwater as well as in hydrocarbon-contaminated aquifers. In hydrocarbon-contaminated sulfidic habitats, the epsilonproteobacterium may generate energy by coupling the oxidation of hydrogen or formate and highly abundant sulfide with the reduction of fumarate and/or polysulfide, accompanied by efficient assimilation of acetate produced during fermentation or incomplete oxidation of hydrocarbons. The highly efficient assimilation of acetate was recently

  12. Regulation of bacterial sulfate reduction and hydrogen sulfide fluxes in the central Namibian coastal upwelling zone

    DEFF Research Database (Denmark)

    Bruchert, V.; Jørgensen, BB; Neumann, K.;

    2003-01-01

    and the low capacity to oxidize and trap sulfide. The inner shelf break marks the seaward border of sulfidic bottom waters, and separates two different regimes of bacterial sulfate reduction. In the sulfidic bottom waters on the shelf, up to 55% of sulfide oxidation is mediated by the large nitrate...... to the sediment-water interface and reduce the hydrogen sulfide flux to the water column. Modeling of pore water sulfide concentration profiles indicates that sulfide produced by bacterial sulfate reduction in the uppermost 16 cm of sediment is sufficient to account for the total flux of hydrogen sulfide...... to the water column. However, the total pool of hydrogen sulfide in the water column is too large to be explained by steady state diffusion across the sediment-water interface. Episodic advection of hydrogen sulfide, possibly triggered by methane eruptions, may contribute to hydrogen sulfide in the water...

  13. Carbonyl sulfide: No remedy for global warming

    Science.gov (United States)

    Taubman, Steven J.; Kasting, James F.

    1995-04-01

    The enhancement of the stratospheric aerosol layer caused by the eruption of Mt. Pinatubo (June 15, 1991), and the subsequent cooling of the earth's lower atmosphere [Dutton and Christy, 1992; Minnis et al., 1993] shows that stratospheric aerosols can have a strong effect on the earth's climate. This supports the notion that the intentional enhancement of the stratospheric aerosol layer through increased carbonyl sulfide (OCS) emissions might be an effective means for counteracting global warming. Through the use of a one-dimensional photochemical model, we investigate what effect such a program might have on global average stratospheric ozone. In addition, we consider the impact of enhanced OCS emissions on rainwater acidity and on the overall health of both plants and animals. We find that while the warming produced by a single CO2 doubling (1 to 4°C) might be offset with ozone losses of less than 5%, any attempt to use carbonyl sulfide as a permanent solution to global warming could result in depletion of global average ozone by 30% or more. We estimate that in order to achieve cooling of 4°C rainwater pH would fall to between 3.5 and 3.8. Finally, a 4°C cooling at the surface will require that ambient near ground OCS levels rise to above 10 ppmv which is probably greater than the safe exposure limit for humans. Thus, enhanced OCS emissions do not provide an environmentally acceptable solution to the problem of global warming.

  14. Normal state of metallic hydrogen sulfide

    Science.gov (United States)

    Kudryashov, N. A.; Kutukov, A. A.; Mazur, E. A.

    2017-02-01

    A generalized theory of the normal properties of metals in the case of electron-phonon (EP) systems with a nonconstant density of electron states has been used to study the normal state of the SH3 and SH2 phases of hydrogen sulfide at different pressures. The frequency dependence of the real Re Σ (ω) and imaginary ImΣ (ω) parts of the self-energy Σ (ω) part (SEP) of the Green's function of the electron Σ (ω), real part Re Z (ω), and imaginary part Im Z (ω) of the complex renormalization of the mass of the electron; the real part Re χ (ω) and the imaginary part Imχ (ω) of the complex renormalization of the chemical potential; and the density of electron states N (ɛ) renormalized by strong electron-phonon interaction have been calculated. Calculations have been carried out for the stable orthorhombic structure (space group Im3¯ m) of the hydrogen sulfide SH3 for three values of the pressure P = 170, 180, and 225 GPa; and for an SH2 structure with a symmetry of I4/ mmm ( D4 h1¯7) for three values of pressure P = 150, 180, and 225 GP at temperature T = 200 K.

  15. First detection of doubly deuterated hydrogen sulfide

    CERN Document Server

    Vastel, C; Ceccarelli, C; Pearson, J

    2003-01-01

    This work was carried out with using the Caltech Submillimeter Observatory and presents the observational study of HDS and D2S towards a sample of Class 0 sources, and dense cores. We report the first detection of doubly deuterated hydrogen sulfide (D2S) in two dense cores and analyze the chemistry of these molecules aiming to help understand the deuteration processes in the interstellar medium. The observed values of the D2S/HDS ratio, and upper limits, require an atomic D/H ratio in the accreting gas of 0.1-1. The study presented in this Letter supports the hypothesis that formaldehyde, methanol and hydrogen sulfide are formed on the grain surfaces, during the cold pre-stellar core phase, where the CO depleted gas has large atomic D/H ratios. The high values for the D/H ratios are consistent with the predictions of a recent gas-phase chemical model that includes H3+ and its deuterated isotopomers, H2D+, D2H+ and D3+ (Roberts et al. 2003).

  16. Calculation of sulfide capacities of multicomponent slags

    Science.gov (United States)

    Pelton, Arthur D.; Eriksson, Gunnar; Romero-Serrano, Antonio

    1993-10-01

    The Reddy-Blander model for the sulfide capacities of slags has been modified for the case of acid slags and to include A12O3 and TiO2 as components. The model has been extended to calculate a priori sulfide capacities of multicomponent slags, from a knowledge of the thermodynamic activities of the component oxides, with no adjustable parameters. Agreement with measurements is obtained within experimental uncertainty for binary, ternary, and quinary slags involving the components SiO2-Al2O3-TiO2-CaO-MgO-FeO-MnO over wide ranges of composition. The oxide activities used in the computations are calculated from a database of model parameters obtained by optimizing thermodynamic and phase equilibrium data for oxide systems. Sulfur has now been included in this database. A computing system with automatic access to this and other databases has been developed to permit the calculation of the sulfur content of slags in multicomponent slag/metal/gas/solid equilibria.

  17. CALCULATION OF CONDITIONAL EQUILIBRIUM IN SERIAL MULTIPLE PRECIPITATION OF METAL SULFIDES WITH HYDROGEN SULFIDE STREAM GENERATED FROM SODIUM SULFIDE: A DIDACTIC TOOL FOR CHEMISTRY TEACHING

    Directory of Open Access Journals (Sweden)

    Renata Bellová

    2016-07-01

    Full Text Available Hydrogen sulfide is presented in textbooks as toxic, environmentally unacceptable species, however some positive effects in human metabolism were discovered in the last decades. It is important to offer students also some new information about this compound. As didactic tool in this case may serve serial precipitation of Cd2+, Cu2+, Zn2+, Mn2+ and Pb2+ ions forming various colored sulfides in bubblers with chemically generated hydrogen sulfide stream. This experiment has strong and diverse color effect for enhancing the visual perception to motivate students to understand more abstract and complex information about hydrogen sulfide. It also may be helpful in analytical chemistry courses for conditional precipitation equilibrium teaching and calculations.

  18. REE Geochemistry of Sulfides from the Huize Zn-Pb Ore Field, Yunnan Province: Implication for the Sources of Ore-forming Metals

    Institute of Scientific and Technical Information of China (English)

    LI Wenbo; HUANG Zhilong; QI Liang

    2007-01-01

    REE abundances in sulfides from the Huize Zn-Pb ore field were determined with the ICPMS after preconcentration. The REE abundances in 26 sulfide samples (including pyrite, galena and sphalerite) are very low, with the ΣREE ranging from 1.6×10-9 to 166.8×10-9. Their LREE/HREE ratios range from 7.6 to 98, showing LREE enrichment relatively. The δEu values are below 1, indicating that they were deposited from an Eu-depleted and reducing fluid-system. Similar to the ore-hosting carbonate strata, calcite separates from carbonate veinlets filling in the fractures or faults crosscutting the carbonate strata also show clear Eu-depletion. This indicates that the carbonate veinlets and their parent fluid was possibly sourced from the strata and inherited the REE geochemical features of the strata. Therefore, REE-geochemical characteristics of both the sulfides and calcites, which were deposited from an ore-forming hydrothermal system, are similar to those of carbonate strata, and strongly suggest that the ore metals were mainly sourced from carbonate strata.

  19. Positive trends in Southern Hemisphere observations of carbonyl sulfide

    Science.gov (United States)

    Kremser, Stefanie; Jones, Nicholas; Smale, Dan; Palm, Mathias; Lejeune, Bernard; Wang, Yuting; Deutscher, Nicholas

    2016-04-01

    Carbonyl sulfide (OCS; lifetime of about 5.7 years) is the longest lived reduced sulfur-containing gas in the atmosphere. The primary source of OCS is the ocean, which is both a direct source (through OCS emission) and an indirect source (due to oxidation of carbon disulfide, CS2, and dimethyl sulfide). Other natural sources of OCS include volcanic outgassing and direct fluxes from wetland regions. The removal of OCS from the atmosphere is dominated by soil and vegetation uptake, with minor contributions from reactions with the hydroxyl radical. Small anthropogenic sources of OCS are coal combustion, biomass burning, and aluminum production. A dominant indirect source results from CS2 emissions from the rayon industry. Transport of tropospheric OCS to the stratosphere during volcanically quiescent periods has been suggested to contribute sulfur to the stratospheric aerosol layer which affects atmospheric radiative balance. If, however, production of stratospheric aerosols from OCS oxidation is smaller than typical estimates, this OCS contribution would be overestimated. The magnitude of the OCS flux to the stratosphere is currently not well quantified as is the relative contribution of OCS to background aerosol loading. While earlier model simulations indicate OCS fluxes into the atmosphere exceeding removal, past total column observations of OCS show no significant trend. Analysis of tropospheric OCS columns at Arrival Heights (Antarctica) and Lauder (New Zealand) show strong positive trends from 2001-2008 followed by weaker trends to 2015, with unexpected temporal coherence. Since trends in ocean and land sources/sinks at these two sites, respectively, are unlikely to be similar, the coherence in trend structure likely results from changes in transport of OCS from the tropics to middle and high latitudes. Potential causes for OCS increases are (i) increases in tropical lower stratospheric OCS and/or (ii) strengthening of the large-scale circulation which

  20. Study of volumetric properties (PVT) of mixtures made of light hydrocarbons (C1-C4), carbon dioxide and hydrogen sulfide - Experimental measurements through a vibrating tube densimeter and modelling; Etude des proprietes volumetriques (PVT) d'hydrocarbures legers (C1-C4), du dioxyde de carbone et de l'hydrogene sulfure. Mesures par densimetrie a tube vibrant et modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Rivollet, F.

    2005-12-15

    Various pollutant contents (i.e. carbon dioxide, hydrogen sulphide or other sulphur products) are found in produced oils. These latter must undergo a number of transformations and purifications. The design and dimensioning of the corresponding units can well be optimized only if one has reliable and accurate data about phase equilibria and volumetric properties and of course reliable and accurate modeling. This work was devoted partly to measurements of volumetric properties on three binary mixtures (ethane - hydrogen sulphide, ethane - propane and carbon dioxide - hydrogen sulphide). These measurements were carried out using equipment, comprising a vibrating tube densimeter (Paar, model DMA 512 P), which was especially designed and built for this work. The binary mixtures were studied in the 253 to 363 K temperature range from at pressures up to either 20 or 40 MPa. Two calibration methods of the vibrating tube were used: the FPMC method (Forced Path Mechanical Calibration) described in the literature and an original method containing neural network, developed herein. The study undertaken about the modeling of volumetric properties made it possible to highlight the inadequacy of the traditional use of cubic equations of state to represent simultaneously volumetric properties and phase equilibria. Among the equations of state investigated, a close attention however was paid to cubic equations of state because of their very great use in the oil field. A new tool was found to adapt cubic equations of state to the simultaneous and satisfactory representation of volumetric properties and phase equilibria. It concerns the coupling of the cubic Redlich-Kwong-Soave equation of state with volume correction through a neural network. This new model was tested successfully, it makes it possible to benefit from the existing work of representation of phase equilibria (mixing rules and interaction coefficients) while improving calculation of the volumetric data.

  1. Sedimentary pyrite δ34S differs from porewater sulfide in Santa Barbara Basin: Proposed role of organic sulfur

    Science.gov (United States)

    Raven, Morgan Reed; Sessions, Alex L.; Fischer, Woodward W.; Adkins, Jess F.

    2016-08-01

    Santa Barbara Basin sediments host a complex network of abiotic and metabolic chemical reactions that knit together the carbon, sulfur, and iron cycles. From a 2.1-m sediment core collected in the center of the basin, we present high-resolution profiles of the concentrations and isotopic compositions of all the major species in this system: sulfate, sulfide (∑H2S), elemental sulfur (S0), pyrite, extractable organic sulfur (OS), proto-kerogen S, total organic and dissolved inorganic carbon, and total and reducible iron. Below 10 cm depth, the core is characterized by low apparent sulfate reduction rates (biogeochemical cycles and redox structure in sedimentary paleoenvironments.

  2. Coupling autotrophic sulfide mineral weathering with dolomite dissolution in a subglacial ecosystem

    Science.gov (United States)

    Boyd, E. S.; Hamilton, T. L.; Havig, J. R.; Lange, R.; Murter, E.; Skidmore, M. L.; Peters, J.; Shock, E.

    2013-12-01

    Evidence in the rock record suggests that glaciers have been present and covered a significant portion of the Earth's surface since the putative Mozaan Glaciation (circa 2.9 Ga) and were demonstrated recently to host active microbial communities that impact local and global biogeochemical cycles. In the present study, we applied a microcosm-based radioisotopic biocarbonate tracer approach to quantify rates of inorganic carbon assimilation in sediments sampled from beneath Robertson Glacier (RG), Alberta, Canada at 4°C. Rates of inorganic carbon assimilation were stimulated by the addition of ammonium and phosphate, suggesting that these nutrients might be of limited supply in the subglacial environment or, in the case of ammonia, might be serving as a source of reductant fueling inorganic carbon fixation. Geochemical analyses were used to assess the potential redox couples that might be fueling autotrophic activity. The difference in the concentration of sulfate (2.4 mM) in unamended microcosm fluids when compared to fluids sampled from killed controls following 180 days incubation suggests that inorganic carbon assimilation in microcosms is driven by microbial populations involved in the oxidation of mineral sulfides, most likely pyrite. Amendment of microcosms with 1 mM ammonia led to near stoichiometric production of nitrate (~890 μM) and lower production of sulfate (~1.5 mM), indicating that the enhanced activity observed in ammonia treated microcosms is likely due to the stimulation of autotrophic ammonia oxidizing populations. The isotopic composition of dissolved organic carbon in subglacial meltwaters ranged was -24.40 ‰ versus VPDB, which is consistent with a source for this organic carbon via the activity of autotrophs that use the Calvin cycle of inorganic carbon fixation. Quantification and sequencing of transcripts of Calvin cycle biomarker genes (ribulose-1,5 bisphosphate carboxylase/oxygenase, encoded by cbbL) suggest the presence of a ubiquitous

  3. Synthesis of Diaryl Ethers, Diaryl Sulfides, Heteroaryl Ethers and Heteroaryl Sulfides under Microwave Heating

    Institute of Scientific and Technical Information of China (English)

    LI,Feng; ZOU,Jiong; WANG,Quan-Rui; TAO,Feng-Gang

    2004-01-01

    @@ Diaryl ether moiety is found in a pool of naturally occurring and medicinally important compounds.[1] As a consequent, considerable efforts have been devoted to the assembly of this framework.[2] Recently, we have developed a microwave heating version of the synthesis of diaryl ethers as well as aryl sulfides. Under our conditions, even the extremely electron-poor 4-nitrophenol works well and its reaction with 1-halo-4-nitrobenzenes produces 4-(nitrophenoxy)-benzonitriles in satisfactory yield. The scope of the present protocol has been expanded to hydroxylated six-membered heterocycles as well as 2-pyrimidinethiol with mildly activated aryl halides, affording heteroaryl ethers and respectively sulfides. The advantages of the present method include the wide substrate scope, no use of any metal catalysts, the ease of product isolation and high yields.

  4. Measurement of plasma hydrogen sulfide in vivo and in vitro.

    Science.gov (United States)

    Shen, Xinggui; Pattillo, Christopher B; Pardue, Sibile; Bir, Shyamal C; Wang, Rui; Kevil, Christopher G

    2011-05-01

    The gasotransmitter hydrogen sulfide is known to regulate multiple cellular functions during normal and pathophysiological states. However, a paucity of concise information exists regarding quantitative amounts of hydrogen sulfide involved in physiological and pathological responses. This is primarily due to disagreement among various methods employed to measure free hydrogen sulfide. In this article, we describe a very sensitive method of measuring the presence of H₂S in plasma down to nanomolar levels, using monobromobimane (MBB). The current standard assay using methylene blue provides erroneous results that do not actually measure H₂S. The method presented herein involves derivatization of sulfide with excess MBB in 100 mM Tris-HCl buffer (pH 9.5, 0.1 mM DTPA) for 30 min in 1% oxygen at room temperature. The fluorescent product sulfide-dibimane (SDB) is analyzed by RP-HPLC using an eclipse XDB-C18 (4.6 × 250 mm) column with gradient elution by 0.1% (v/v) trifluoroacetic acid in acetonitrile. The limit of detection for sulfide-dibimane is 2 nM and the SDB product is very stable over time, allowing batch storage and analysis. In summary, our MBB method is suitable for sensitive quantitative measurement of free hydrogen sulfide in multiple biological samples such as plasma, tissue and cell culture lysates, or media.

  5. Azo dye decolorization assisted by chemical and biogenic sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Prato-Garcia, Dorian [Laboratory for Research on Advanced Processes for Water Treatment, Unidad Académica Juriquilla, Instituto de Ingeniería, Universidad Nacional Autónoma de México, Blvd. Juriquilla 3001, Querétaro 76230 (Mexico); Cervantes, Francisco J. [División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa de San José 2055, San Luis Potosí 78216 (Mexico); Buitrón, Germán, E-mail: gbuitronm@ii.unam.mx [Laboratory for Research on Advanced Processes for Water Treatment, Unidad Académica Juriquilla, Instituto de Ingeniería, Universidad Nacional Autónoma de México, Blvd. Juriquilla 3001, Querétaro 76230 (Mexico)

    2013-04-15

    Highlights: ► Azo dyes were reduced efficiently by chemical and biogenic sulfide. ► Biogenic sulfide was more efficient than chemical sulfide. ► There was no competition between dyes and sulfate for reducing equivalents. ► Aromatic amines barely affected the sulfate-reducing process. -- Abstract: The effectiveness of chemical and biogenic sulfide in decolorizing three sulfonated azo dyes and the robustness of a sulfate-reducing process for simultaneous decolorization and sulfate removal were evaluated. The results demonstrated that decolorization of azo dyes assisted by chemical sulfide and anthraquinone-2,6-disulfonate (AQDS) was effective. In the absence of AQDS, biogenic sulfide was more efficient than chemical sulfide for decolorizing the azo dyes. The performance of sulfate-reducing bacteria in attached-growth sequencing batch reactors suggested the absence of competition between the studied azo dyes and the sulfate-reducing process for the reducing equivalents. Additionally, the presence of chemical reduction by-products had an almost negligible effect on the sulfate removal rate, which was nearly constant (94%) after azo dye injection.

  6. Tracking photosynthetic sulfide oxidation in a meromictic lake using sulfate δ34S and δ18O

    Science.gov (United States)

    Gilhooly, W. P.; Reinhard, C.; Lyons, T. W.; Glass, J. B.

    2012-12-01

    Phototrophic sulfur bacteria oxidize sulfide and fix carbon dioxide in the presence of sunlight without producing oxygen. Environmental conditions in the Paleo- and Mesoproterozoic, when atmospheric oxygen concentrations were at low levels and portions of the oceans were anoxic and sulfidic (euxinic), were conducive to widespread carbon fixation by anoxygenic photosynthesis. This pathway may have helped sustain euxinic conditions in the Proterozoic water column. With limited organic biomarker and geochemical evidence for widespread production of anoxygenic phototrophs, however, additional proxies are needed to fingerprint paleoecological and biogeochemical signals associated with photic zone euxinia. Paired δ34S and δ18O from ancient sulfates (gypsum, barite, or CAS) may offer an added constraint on the history and ecological dominance of photosynthetic S-oxidation. Sulfate-oxygen can fractionate during sulfate reduction, but the extent of isotopic enrichment is controlled either by kinetic isotope effects imparted during intracellular enzymatic steps or equilibrium oxygen exchange with ambient water. An improved understanding of these processes can be gained from modern natural environments. Mahoney Lake is a density-stratified lake located within the White Lake Basin of British Columbia. The euxinic water column supports a dense plate of purple sulfur bacteria (Amoebobacter purpureus) that thrives where free sulfide intercepts the photic zone at ~7 m water depth. We analyzed the isotopic composition of sulfate (δ34SSO4 and δ18OSO4), sulfide (δ34SH2S), and water (δ18OH2O) to track the potentially coupled processes of dissimilatory sulfate reduction and phototrophic sulfide oxidation within this meromictic lake. Large isotopic offsets observed between sulfate and sulfide within the monimolimnion (δ34SSO4-H2S = 51‰) and within pore waters along the oxic margin (δ34SSO4-H2S >50‰) are consistent with sulfate reduction in both the sediments and the anoxic

  7. The sulfur partition ratio and the sulfide capacity of Na2O-SiO2 slags at 1200 °C

    Science.gov (United States)

    Chan, Allen H.; Fruehan, R. J.

    1986-09-01

    The sulfur partition ratio between carbon-saturated iron and Na2O-SiO2 slags and the sulfide capacity of these slags have been measured at 1200 °C. The two measurements are consistent with each other and the results are compared with other investigations. These slags have higher sulfide capacities and partition ratios than equivalent CaO-based slags and are thus attractive desulfurizers. Both the sulfide capacity and the partition ratio increase with increasing Na2O. The activity coefficient of Na2S has been calculated; it also increases with increasing Na2O. The solubility of sulfur in a slag of 0.4 mole fraction Na2O is estimated to be 5 pct.

  8. Gallium sulfide and indium sulfide nanoparticles from complex precursors: Synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, D.P. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)]. E-mail: duttadimple@yahoo.co.in; Sharma, G. [Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Tyagi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kulshreshtha, S.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2007-03-15

    Nanocrystalline gallium sulfide (Ga{sub 2}S{sub 3}) and indium sulfide (In{sub 2}S{sub 3}) have been prepared by a two-step process. The first step involves metathesis reaction of trimethyl gallium/indium ether adduct (Me{sub 3}Ga/In.OEt{sub 2}) with 1,2-ethanedithiol (HSCH{sub 2}CH{sub 2}SH) resulting in the formation of a polymeric precursor. The precursor complex has been characterized using Ga/In analysis, IR, proton NMR and mass spectroscopy. The thermal behavior of both complexes has been studied using thermogravimetric (TG) analysis. In the second step, these precursor complexes have been pyrolysed in furnace under flowing nitrogen atmosphere whereupon they undergo thermodestruction to yield nanometer-sized particles of gallium/indium sulfide. The nanoparticles obtained were characterized using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDS). The average size of the nanoparticles ranged from 10 to 12 nm for Ga{sub 2}S{sub 3} and 20 to 22 nm for In{sub 2}S{sub 3}, respectively. This is the first report on use of a binary single source precursor to synthesize {beta}-Ga{sub 2}S{sub 3} nanoparticles.

  9. Nanostructured cobalt sulfide-on-fiber with tunable morphology as electrodes for asymmetric hybrid supercapacitors

    KAUST Repository

    Baby, Rakhi Raghavan

    2014-01-01

    Porous cobalt sulfide (Co9S8) nanostructures with tunable morphology, but identical crystal phase and composition, have been directly nucleated over carbon fiber and evaluated as electrodes for asymmetric hybrid supercapacitors. As the morphology is changed from two-dimensional (2D) nanoflakes to 3D octahedra, dramatic changes in supercapacitor performance are observed. In three-electrode configuration, the binder-free Co9S82D nanoflake electrodes show a high specific capacitance of 1056 F g-1at 5 mV s-1vs. 88 F g-1for the 3D electrodes. As sulfides are known to have low operating potential, for the first time, asymmetric hybrid supercapacitors are constructed from Co9S8nanostructures and activated carbon (AC), providing an operation potential from 0 to 1.6 V. At a constant current density of 1 A g-1, the 2D Co9S8, nanoflake//AC asymmetric hybrid supercapacitor exhibits a gravimetric cell capacitance of 82.9 F g-1, which is much higher than that of an AC//AC symmetric capacitor (44.8 F g-1). Moreover, the asymmetric hybrid supercapacitor shows an excellent energy density of 31.4 W h kg-1at a power density of 200 W Kg-1and an excellent cycling stability with a capacitance retention of ∼90% after 5000 cycles. This journal is

  10. Signaling of hydrogen sulfide and polysulfides.

    Science.gov (United States)

    Kimura, Hideo

    2015-02-10

    It has been almost two decades since the first demonstration of hydrogen sulfide (H2S) as a physiological mediator of cognitive function and vascular tone. H2S is physiologically important because it protects various organs from ischemia-reperfusion injury besides regulating inflammation, oxygen sensing, cell growth, and senescence. The production, metabolism, and regulation of H2S have been studied extensively. H2S modulates target proteins through sulfhydration (or sulfuration) or by the reduction of cysteine disulfide bonds. A large number of novel H2S-donating compounds are being developed owing to the therapeutic potential of H2S. Recently, polysulfides, rather than H2S, have been identified as molecules that sulfhydrate (or sulfurate) their target proteins.

  11. Hydrogen sulfide in a circumstellar envelope

    Science.gov (United States)

    Ukita, N.; Morris, M.

    1983-01-01

    A search for hydrogen sulfide in the cool circumstellar envelopes of 25 stars was made using the 1(10)-1(01) rotational line at 1.8 mm. It was detected in the bipolar nebula/OH maser OH231.8+4.2, an object having a high rate of mass loss. An approximate analysis indicates that 1/60 of the sulfur in this outflowing envelope is in the form of H2S, a fraction which may be similar to that in the atmosphere of the central star. In addition, the shape of the observed line profile is discussed in terms of a possible variation of the outflow velocity with latitude above the system's equatorial plane.

  12. Hydrogen sulfide in gastrointestinal and liver physiopathology.

    Science.gov (United States)

    Cipriani, Sabrina; Mencarelli, Andrea

    2011-04-01

    Hydrogen sulfide (H(2)S) is a gas that can be formed by the action of two enzymes, cystathionine gamma lyase (CSE) and cystathionine beta synthase (CBS). H(2)S has been known for hundreds of years for its poisoning effect, however the idea that H(2)S is not only a poison, but can exert a physiological role in mammalian organisms, originates from the evidence that this gaseous mediator is produced endogenously. In addition to H(2)S synthesis by gastrointestinal tissue, the intestinal mucosa, particularly in the large intestine, is regularly exposed to high concentrations of H(2)S that are generated by some species of bacteria and through the reduction of unabsorbed intestinal inorganic sulphate. This review reports on the effects of H(2)S in the gastrointestinal tract and liver and provides information on the therapeutic applications of H(2)S-donating drugs.

  13. Study of the interaction between water and hydrogen sulfide with polycyclic aromatic hydrocarbons.

    Science.gov (United States)

    Cabaleiro-Lago, Enrique M; Carrazana-García, Jorge A; Rodríguez-Otero, Jesús

    2009-06-21

    A computational study has been carried out for determining the characteristics of the interaction between one water and hydrogen sulfide molecule with a series of polycyclic aromatic hydrocarbons of increasing size, namely, benzene, anthracene, triphenylene, coronene, circumcoronene, and dicircumcoronene. Potential energy curves were calculated for structures where H(2)X (X=O,S) molecule is located over the central six-membered ring with its hydrogen atoms pointing toward to (mode A) or away from (mode B) the hydrocarbon. The accuracy of different methods has been tested against the results of coupled cluster calculations extrapolated to basis set limit for the smaller hydrocarbons. The spin component scaled MP2 (SCS-MP2) method and a density functional theory method empirically corrected for dispersion (DFT-D) reproduce fairly well the results of high level calculations and therefore were employed for studying the larger systems, though DFT-D seems to underestimate the interaction in hydrogen sulfide clusters. Water complexes in mode A have interaction energies that hardly change with the size of the hydrocarbon due to compensation between the increase in the correlation contribution to the interaction energy and the increase in the repulsive character of the Hartree-Fock energy. For all the other clusters studied, there is a continuous increase in the intensity of the interaction as the size of the hydrocarbon increases, suggesting already converged values for circumcoronene. The interaction energy for water clusters extrapolated to an infinite number of carbon atoms amounts to -13.0 and -15.8 kJ/mol with SCS-MP2 and DFT-D, respectively. Hydrogen sulfide interacts more strongly than water with the hydrocarbons studied, leading to a limiting value of -21.7 kJ/mol with the SCS-MP2 method. Also, complexes in mode B are less stable than the corresponding A structures, with interaction energies amounting to -8.2 and -18.2 kJ/mol for water and hydrogen sulfide

  14. Nanomaterials for the Selective Detection of Hydrogen Sulfide in Air

    Science.gov (United States)

    Llobet, Eduard; Brunet, Jérôme; Pauly, Alain; Ndiaye, Amadou; Varenne, Christelle

    2017-01-01

    This paper presents a focused review on the nanomaterials and associated transduction schemes that have been developed for the selective detection of hydrogen sulfide. It presents a quite comprehensive overview of the latest developments, briefly discusses the hydrogen sulfide detection mechanisms, identifying the reasons for the selectivity (or lack of) observed experimentally. It critically reviews performance, shortcomings, and identifies missing or overlooked important aspects. It identifies the most mature/promising materials and approaches for achieving inexpensive hydrogen sulfide sensors that could be employed in widespread, miniaturized, and inexpensive detectors and, suggests what research should be undertaken for ensuring that requirements are met. PMID:28218674

  15. Effect of radiation on wettability and floatability of sulfide minerals

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The feasibility for modifying the wettability and floatability of sulfide minerals by electron beam irradiation has been studied experimentally. The wettability of crystalline pyrite and floatability of some sulfide as pyrite, arsenopyrite, chalcopyrite and marmatite after irradiation were examined by flotation in a modified Hallimond tube. Experimental results show that the hydrophobicity of crystalline pyrite enhances with the increase of irradiation dose in a low dose range. And the flotation responses of sulfide minerals on irradiation dosevary with the mineral species and particle size. The floatability of minerals can be regulated by altering irradiation dose. An explanationfor the mechanism has been suggested based on the principle of radiation chemistry.

  16. Sulfide capacities of MnO-SiO2 slags

    Science.gov (United States)

    Reddy, Ramana G.; Blander, Milton

    1989-04-01

    Sulfide capacities of binary MnO-SiO2 slags at 1773 and 1923 K were calculated thermodynamically. Only known data, such as the standard free energy of formation of MnO and MnS and activities of MnO in the melt, are used in making calculations based on fundamental concepts. Excellent agreement is found between our calculations and published experimental data. Correlations of sulfide capacities, based on optical basicity using Pauling electronegativities or empirically deduced optical basicities, differ from the experimental data in both magnitude and concentration dependence. Our method provides useful predictions of sulfide capacities a priori.

  17. Metabolism in the Uncultivated Giant Sulfide-Oxidizing Bacterium Thiomargarita Namibiensis Assayed Using a Redox-Sensitive Dye

    Science.gov (United States)

    Bailey, J.; Flood, B.; Ricci, E.

    2014-12-01

    The colorless sulfur bacteria are non-photosynthetic chemolithotrophs that live at interfaces between nitrate, or oxygen, and hydrogen sulfide. In sulfidic settings such as cold seeps and oxygen minimum zones, these bacteria are thought to constitute a critical node in the geochemical cycling of carbon, sulfur, nitrogen, and phosphorous. Many of these bacteria remain uncultivated and their metabolisms and physiologies are incompletely understood. Thiomargarita namibiensis is the largest of these sulfur bacteria, with individual cells reaching millimetric diameters. Despite the current inability to maintain a Thiomargarita culture in the lab, their large size allows for individual cells to be followed in time course experiments. Here we report on the novel use of a tetrazolium-based dye that measures the flux of NADH production from catabolic pathways via a colorimetric response. Staining with this dye allows for metabolism to be detected, even in the absence of observable cell division. When coupled to microscopy, this approach also allows for metabolism in Thiomargaritato be differentiated from that of epibionts or contaminants in xenic samples. The results of our tetrazolium dye-based assay suggests that Thiomargarita is the most metabolically versatile under anoxic conditions where it appears capable of using acetate, succinate, formate, thiosulfate, citrate, thiotaurine, hydrogen sulfide, and perhaps hydrogen as electron donors. Under hypoxic conditions, staining results suggest the utilization of acetate, citrate, and hydrogen sulfide. Cells incubated under oxic conditions showed the weakest tetrazolium staining response, and then only to hydrogen sulfide and questionably succinate. These initial results using a redox sensitive dye suggest that Thiomargarita is most metabolically versatile under anaerobic and hypoxic conditions. The results of this assay can be further evaluated using molecular approaches such as transcriptomics, as well as provide cultivation

  18. Micellar-mediated extractive spectrophotometric determination of hydrogen sulfide/sulfide through Prussian Blue reaction: application to environmental samples.

    Science.gov (United States)

    Pandurangappa, Malingappa; Samrat, Devaramani

    2010-01-01

    A sensitive surfactant-mediated extractive spectrophotometric method has been developed, based on the reaction of ferric iron with sulfide to form ferrous iron and its subsequent reaction with ferricyanide to form Prussian Blue, to quantify trace levels of hydrogen sulfide/sulfide in environmental samples. The method obeys Beer's law in the concentration range 2-10 microg of sulfide in 25 mL of aqueous phase with molar absorptivity (epsilon) of 3.92 x 10(4) L mol(-1) cm(-1). The colored species has been extracted into isoamyl acetate in the presence of a cationic surfactant i.e. cetylpyridinium chloride, to enhance the sensitivity of the method with epsilon value 5.2 x 10(4) L mol(-1) cm(-1). The relative standard deviation has been found to be 0.69% for 10 determinations at 4 microg of sulfide and the limit of detection was 0.009 microg mL(-1). The interference from common anions and cations has been studied. The proposed method has been applied to the determination of residual hydrogen sulfide in the laboratory fume hood as well as ambient atmospheric hydrogen sulfide in the vicinity of open sewer lines after fixing the analyte in ionic form using suitable trapping medium.

  19. Micro-aeration for hydrogen sulfide removal from biogas

    Science.gov (United States)

    Duangmanee, Thanapong

    The presence of sulfur compounds (e.g. protein, sulfate, thiosulfate, sulfite, etc.) in the feed stream generates highly corrosive and odorous hydrogen sulfide during anaerobic digestion. The high sulfide level in the biogas stream is not only poisonous to many novel metal catalysts employed in thermo-catalytic processes but also reduces the quality of methane to produce renewable energy. This study used an innovative, low-maintenance, low-cost biological sulfide removal technology to remove sulfides simultaneously from both gas and liquid phase. ORP (Oxidation-Reduction-Potential) was used as the controlling parameter to precisely regulate air injection to the sulfide oxidizing unit (SOU). The microaeration technique provided just enough oxygen to partially oxidize sulfides to elemental sulfur without inhibiting methanogenesis. The SOU was equipped with a diffuser at the bottom for the dispersion of sulfide-laden biogas and injected air throughout the column. The SOU can be operated as a standalone unit or coupled with an anaerobic digester to simultaneously remove sulfide from the biogas and effluent. The integrated system was capable of reducing hydrogen sulfide in biogas from 2,450 to less than 2 ppmV with minimal sulfate production at the highest available sulfide loading rate of 0.24 kg/m3-day. More than 98% of sulfide removed was recovered as elemental sulfur. However, the standalone SOU was able to operate at high hydrogen sulfide loading of 1.46 kg/m 3-day at inlet sulfide concentration of 3000 ppmV and reduce the off-gas hydrogen sulfide concentrations to less than 10 ppmV. The experiment also revealed that the ORP controlled aeration was sensitive enough to prevent oxygen overdosing (dampening effect) during unexpected surges of aeration. Using generalized linear regression, a model predicting output H2S concentration based on input H2S concentrations, SOU medium heights, and biogas flow rates, was derived. With 95% confidence, output H2S concentration

  20. Hydrogen Sulfide Micro-Sensor for Biomass Fouling Detection Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Hydrogen Sulfide (H2S)is the leading chemical agent causing human fatalities following inhalation exposures. The overall aim of this project is to develop and...

  1. Nanostructured Metal Oxides and Sulfides for Lithium-Sulfur Batteries.

    Science.gov (United States)

    Liu, Xue; Huang, Jia-Qi; Zhang, Qiang; Mai, Liqiang

    2017-02-03

    Lithium-sulfur (Li-S) batteries with high energy density and long cycle life are considered to be one of the most promising next-generation energy-storage systems beyond routine lithium-ion batteries. Various approaches have been proposed to break down technical barriers in Li-S battery systems. The use of nanostructured metal oxides and sulfides for high sulfur utilization and long life span of Li-S batteries is reviewed here. The relationships between the intrinsic properties of metal oxide/sulfide hosts and electrochemical performances of Li-S batteries are discussed. Nanostructured metal oxides/sulfides hosts used in solid sulfur cathodes, separators/interlayers, lithium-metal-anode protection, and lithium polysulfides batteries are discussed respectively. Prospects for the future developments of Li-S batteries with nanostructured metal oxides/sulfides are also discussed.

  2. Selective adsorption of bacteria on sulfide minerals surface

    Institute of Scientific and Technical Information of China (English)

    JIA Chun-yun; WEI De-zhou; LIU Wen-gang; HAN Cong; GAO Shu-ling; WANG Yu-juan

    2008-01-01

    The adsorption of bacteria on sulfide minerals surface was studied, and the selective adsorption mechanism of cells on the sulfide minerals was investigated by means of FTIR, UVS and XPS. The results show that the three strains of bacteria adsorbed more preferentially on pyrite than on other two sulfide minerals surface at neutral and alkaline pH conditions. FTIR and UVS of three strains of bacteria indicate that there are more functional groups on their surface, such as O-H, C=O, N-H, C-O, and the content of saccharide is more than that of protein. The state of every element on sulfide minerals surface was analyzed by XPS. The empty orbital number of electronic shell of metal ions on minerals surface is important in selective adsorption process, and some stable constants of metal coordinates can be used to explain the contribution of some groups in saccharide of cell wall to the selective adsorption.

  3. An Experiment in Autotrophic Fermentation: Microbial Oxidation of Hydrogen Sulfide.

    Science.gov (United States)

    Sublette, Kerry L.

    1989-01-01

    Described is an experiment which uses an autotrophic bacterium to anaerobically oxidize hydrogen sulfide to sulfate in a batch-stirred tank reactor. Discusses background information, experimental procedure, and sample results of this activity. (CW)

  4. Optimization of biological sulfide removal in a CSTR bioreactor.

    Science.gov (United States)

    Roosta, Aliakbar; Jahanmiri, Abdolhossein; Mowla, Dariush; Niazi, Ali; Sotoodeh, Hamidreza

    2012-08-01

    In this study, biological sulfide removal from natural gas in a continuous bioreactor is investigated for estimation of the optimal operational parameters. According to the carried out reactions, sulfide can be converted to elemental sulfur, sulfate, thiosulfate, and polysulfide, of which elemental sulfur is the desired product. A mathematical model is developed and was used for investigation of the effect of various parameters on elemental sulfur selectivity. The results of the simulation show that elemental sulfur selectivity is a function of dissolved oxygen, sulfide load, pH, and concentration of bacteria. Optimal parameter values are calculated for maximum elemental sulfur selectivity by using genetic algorithm as an adaptive heuristic search. In the optimal conditions, 87.76% of sulfide loaded to the bioreactor is converted to elemental sulfur.

  5. Assessing the Role of Iron Sulfides in the Long Term Sequestration of Uranium by Sulfate-Reducing Bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, Kim F.; Bi, Yuqiang; Carpenter, Julian; Hyng, Sung Pil; Rittmann, Bruce E.; Zhou, Chen; Vannela, Raveender; Davis, James A.

    2014-01-01

    iron was poorly crystalline. At UM, laboratory-scale reactor studies were performed to assess the potential for the predominant abiotic reductants formed under sulfate reducing conditions (SRCs) to: (1) reduce U(VI) in contaminated groundwater sediments), and (2) inhibit the re-oxidation of U(IV) species, and in particular, uraninite (UO2(s)). Under SRCs, mackinawite and aqueous sulfide are the key reductants expected to form. To assess their potential for abiotic reduction of U(VI) species, a series of experiments were performed in which either FeS or S(-II) was added to solutions of U(VI), with the rates of conversion to U(IV) solids monitored as a function of pH, and carbonate and calcium concentration. In the presence of FeS and absence of oxygen or carbonate, U(IV) was completely reduced uraninite. S(-II) was also found to be an effective reductant of aqueous phase U(VI) species and produced uraninite, with the kinetics and extent of reduction depending on geochemical conditions. U(VI) reduction to uraninite was faster under higher S(-II) concentrations but was slowed by an increase in the dissolved Ca or carbonate concentration. Rapid reduction of U(VI) occurred at circumneutral pH but virtually no reduction occurred at pH 10.7. In general, dissolved Ca and carbonate slowed abiotic U(VI) reduction by forming stable Ca-U(VI)-carbonate soluble complexes that are resistant to reaction with aqueous sulfide. To investigate the stability of U(IV) against re-oxidation in the presence of iron sulfides by oxidants in simulated groundwater environments, and to develop a mechanistic understanding the controlling redox processes, continuously-mixed batch reactor (CMBR) and flow-through reactor (CMFR) studies were performed at UM. In these studies a series of experiments were conducted under various oxic groundwater conditions to examine the effectiveness of FeS as an oxygen scavenger to retard UO2 dissolution. The results indicate that FeS is an effective oxygen scavenger

  6. An eco-friendly oxidation of sulfide compounds

    Indian Academy of Sciences (India)

    RAVINDRA B WAGH; SITARAM H GUND; JAYASHREE M NAGARKAR

    2016-08-01

    An improved green route has been developed for the oxidation of sulfide compounds. Albendazole is converted to ricobendazole or albendazole sulfone using H₂O₂ as an oxidant and H₂O as the solvent. High yields of the corresponding products were obtained by carrying out the reaction at room temperature. This synthetic method is environmentally clean and safe, operationally simple for the oxidation of other benzimidazole anthelmintics and various sulfide compounds.

  7. LUMINESCENCE OF CADMIUM SULFIDE QUANTUM DOTS IN FLUOROPHOSPHATE GLASSES

    OpenAIRE

    Z. O. Lipatova; E. V. Kolobkova; V. A. Aseev

    2015-01-01

    Cadmium sulfide quantum dots are perspective materials in optics, medicine, biology and optoelectronics. Fluorophosphate glasses, doped with cadmium sulfide quantum dots, were examined in the paper. Heat treatment led to the formation of quantum dots with diameters equal to 2.8 nm, 3.0 nm and 3.8 nm. In view of such changes in the quantum dots size the fundamental absorption edge shift and the luminescence band are being displaced to the long wavelengths. Luminescence lifetime has been fou...

  8. The role of hydrogen sulfide in renal system

    Directory of Open Access Journals (Sweden)

    Xu Cao

    2016-10-01

    Full Text Available Hydrogen sulfide (H2S has gained recognition as the third gaseous signaling molecule after nitric oxide (NO and carbon monoxide (CO. This review surveys the emerging role of H2S in mammalian renal system, with emphasis on both renal physiology and diseases. H2S is produced redundantly by four pathways in kidney, indicating the abundance of this gaseous molecule in the organ. In physiological conditions, H2S was found to regulate the excretory function of the kidney possibly by the inhibitory effect on sodium transporters on renal tubular cells. Likewise, it also influences the release of renin from juxtaglomerular (JG cells and thereby modulates blood pressure. A possible role of H2S as an oxygen sensor has also been discussed, especially at renal medulla. Alternation of H2S level has been implicated in various pathological conditions such as renal ischemia/reperfusion, obstructive nephropathy, diabetic nephropathy and hypertensive nephropathy. Moreover, H2S donors exhibit broad beneficial effects in renal diseases although a few conflicts need to be resolved. Further research reveals that multiple mechanisms are underlying the protective effects of H2S, including anti-inflammation, anti-oxidation and anti-apoptosis. In the review, several research directions are also proposed including the role of mitochondrial H2S in renal diseases, H2S delivery to kidney by targeting D-amino acid oxidase/3-mercaptopyruvate sulfurtransferase (DAO/3-MST pathway, effect of drug-like H2S donors in kidney diseases and understanding the molecular mechanism of H2S. The completion of the studies in these directions will not only improves our understanding of renal H2S functions but may also be critical to translate H2S to be a new therapy for renal diseases.

  9. The Role of Hydrogen Sulfide in Renal System

    Science.gov (United States)

    Cao, Xu; Bian, Jin-Song

    2016-01-01

    Hydrogen sulfide has gained recognition as the third gaseous signaling molecule after nitric oxide and carbon monoxide. This review surveys the emerging role of H2S in mammalian renal system, with emphasis on both renal physiology and diseases. H2S is produced redundantly by four pathways in kidney, indicating the abundance of this gaseous molecule in the organ. In physiological conditions, H2S was found to regulate the excretory function of the kidney possibly by the inhibitory effect on sodium transporters on renal tubular cells. Likewise, it also influences the release of renin from juxtaglomerular cells and thereby modulates blood pressure. A possible role of H2S as an oxygen sensor has also been discussed, especially at renal medulla. Alternation of H2S level has been implicated in various pathological conditions such as renal ischemia/reperfusion, obstructive nephropathy, diabetic nephropathy, and hypertensive nephropathy. Moreover, H2S donors exhibit broad beneficial effects in renal diseases although a few conflicts need to be resolved. Further research reveals that multiple mechanisms are underlying the protective effects of H2S, including anti-inflammation, anti-oxidation, and anti-apoptosis. In the review, several research directions are also proposed including the role of mitochondrial H2S in renal diseases, H2S delivery to kidney by targeting D-amino acid oxidase/3-mercaptopyruvate sulfurtransferase (DAO/3-MST) pathway, effect of drug-like H2S donors in kidney diseases and understanding the molecular mechanism of H2S. The completion of the studies in these directions will not only improves our understanding of renal H2S functions but may also be critical to translate H2S to be a new therapy for renal diseases.

  10. Arsenic chemistry with sulfide, pyrite, zero-valent iron, and magnetite

    Science.gov (United States)

    Sun, Fenglong

    The aim of this thesis is to study the immobilization reactions of arsenic in water. Since compounds containing iron or sulfide are common in most natural and engineered systems, the research focused on the redox reactions and adsorption of arsenic with sulfide, pyrite, zero-valent iron (ZVI), and magnetite which were studied through wet chemistry methods and spectroscopic techniques. The kinetic and thermodynamic information of the reactions of As(V) with S(-II), As(V)/As(III) with pyrite and surface-oxidized pyrite, As(V) with ZVI and acid-treated ZVI, As(III) with magnetite was used to identify mechanisms. The necessity to maintain strictly anoxic conditions was emphasized for the study of arsenic redox chemistry with sulfides and ZVI. The major findings of this research can be stated as follows. First, dissolved sulfide reduced As(V) to lower valences to form a yellow precipitate at acidic pH. The reaction involved the formation of thioarsenic intermediate species. Dissolved O2, granular activated carbon (GAC) and dissolved Fe(II) inhibited the removal of As(V) by sulfide. Elemental sulfur catalyzed the reduction of As(V) by sulfide, which implied the possible benefit of using sulfur-loaded GAC for arsenic removal. Possible reaction mechanisms were discussed. Second, As(III) adsorbed on pristine pyrite over a broader pH range than on surface-oxidized pyrite, while As(V) adsorbed over a narrower pH range with pristine pyrite. As(V) was completely reduced to As(III) on pristine pyrite at acidic pH but not at higher pH. The reduction was first-order with respect to As(V). As(V) was not reduced on surface-oxidized pyrite at pH = 4--11. The different behaviors of As(V) and As(III) on pristine and surface oxidized pyrite determines the toxicity and mobility of arsenic under oxic/anoxic environments. Third, commercial ZVI reduced As(V) to As(III) at low pH (treated ZVI reduced As(V) to As(0), indicated by wet chemical analyses and by XANES/EXAFS, which could result in

  11. Sulfide oxidation in fluidized bed bioreactor using nylon support material

    Institute of Scientific and Technical Information of China (English)

    Varsha Midha; M K Jha; Apurba Dey

    2012-01-01

    A continuous fluidized bed bioreactor(FBBR)with nylon support particles was used to treat synthetic sulfide wastewater at different hydraulic retention time of 25,50 and 75 min and upflow velocity of 14,17 and 20 m/hr.The effects of upflow velocity,hydraulic retention time and reactor operation time on sulfide oxidation rate were studied using statistical model.Mixed culture obtained from the activated sludge,taken from tannery effluent treatment plant,was used as a source for microorganisms.The diameter and density of the nylon particles were 2-3 mm and 1140 kg/m3,respectively.Experiments were carried out in the reactor at a temperature of(30± 2)℃,at a fixed bed height of 16 cm after the formation of biofilm on the surface of support particles.Biofilm thickness reached(42±3)μm after 15 days from reactor start-up.The sulfide oxidation,sulfate and sulfur formation is examined at all hydraulic retention times and upflow velocities.The results indicated that almost 90%-92% sulfide oxidation was achieved at all hydraulic retention times.Statistical model could explain 94% of the variability and analysis of variance showed that upflow velocity and hydraulic retention time slightly affected the sulfide oxidation rate.The highest sulfide oxidation of 92% with 70% sulfur was obtained at hydraulic retention time of 75 min and upflow velocity of 14 m/hr.

  12. Sulfide oxidation in fluidized bed bioreactor using nylon support material.

    Science.gov (United States)

    Midha, Varsha; Jha, M K; Dey, Apurba

    2012-01-01

    A continuous fluidized bed bioreactor (FBBR) with nylon support particles was used to treat synthetic sulfide wastewater at different hydraulic retention time of 25, 50 and 75 min and upflow velocity of 14, 17 and 20 m/hr. The effects of upflow velocity, hydraulic retention time and reactor operation time on sulfide oxidation rate were studied using statistical model. Mixed culture obtained from the activated sludge, taken from tannery effluent treatment plant, was used as a source for microorganisms. The diameter and density of the nylon particles were 2-3 mm and 1140 kg/m3, respectively. Experiments were carried out in the reactor at a temperature of (30 +/- 2) degrees C, at a fixed bed height of 16 cm after the formation of biofilm on the surface of support particles. Biofilm thickness reached (42 +/- 3) microm after 15 days from reactor start-up. The sulfide oxidation, sulfate and sulfur formation is examined at all hydraulic retention times and upflow velocities. The results indicated that almost 90%-92% sulfide oxidation was achieved at all hydraulic retention times. Statistical model could explain 94% of the variability and analysis of variance showed that upflow velocity and hydraulic retention time slightly affected the sulfide oxidation rate. The highest sulfide oxidation of 92% with 70% sulfur was obtained at hydraulic retention time of 75 min and upflow velocity of 14 m/hr.

  13. Sulfide Oxidation in the Anoxic Black-Sea Chemocline

    DEFF Research Database (Denmark)

    JØRGENSEN, BB; FOSSING, H.; WIRSEN, CO;

    1991-01-01

    The depth distributions of O2 and H2S and of the activity of chemical or bacterial sulfide oxidation were studied in the chemocline of the central Black Sea. Relative to measurements from earlier studies, the sulfide zone had moved upwards by 20-50 m and was now (May 1988) situated at a depth of 81......-99 m. Oxygen in the water column immediately overlying the sulfide zone was depleted to undetectable levels resulting in a 20-30-m deep intermediate layer of O2- and H2S-free water. Radiotracer studies with S-35-labelled H2S showed that high rates of sulfide oxidation, up to a few micromoles per liter...... to a maximum of 200 nmol l-1 at the top of the sulfide zone. Sulfide oxidation was stimulated by particles suspended at the chemocline, probably by bacteria. Green phototrophic sulfur bacteria were abundant in the chemocline, suggesting that photosynthetic H2S oxidation took place. Flux calculations showed...

  14. Sulfide capacity of high alumina blast furnace slags

    Science.gov (United States)

    Shankar, Amitabh; Görnerup, Märten; Seetharaman, S.; Lahiri, A. K.

    2006-12-01

    Sulfide capacities of high alumina blast furnace slags were experimentally determined using the gas-slag equilibration technique. Two different slag systems were considered for the current study, namely, CaO-SiO2-MgO-Al2O3 quaternary and CaO-SiO2-MgO-Al2O3-TiO2 quinary system. The liquid slag was equilibrated with the Ar-CO-CO2-SO2 gas mixture. Experiments were conducted in the temperature range of 1773 to 1873 K. The effects of temperature, basicity, and the MgO and TiO2 contents of slags on sulfide capacity were studied. As expected, sulfide capacity was found to increase with the increase in temperature and basicity. At the higher experimental temperature, titania decreases the sulfide capacity of slag. However, at the lower temperature, there was no significant effect of titania on the sulfide capacity of slag. Sulfide capacity increases with the increase in MgO content of slag if the MgO content is more than 5 pct.

  15. Dihydrogen Activation by Titanium Sulfide Complexes

    Science.gov (United States)

    Sweeney, Zachary K.; Polse, Jennifer L.; Bergman*, Robert G.; Andersen*, Richard A.

    2005-01-01

    The titanocene sulfido complex Cp*2Ti(S)py (1, Cp* = pentamethylcyclopentadienyl; py = pyridine) is synthesized by addition of a suspension of S8 to a toluene solution of Cp*2Ti-(CH2CH2) (2) and py. The rate of rotation of the pyridine ligand in solution was determined by 1H NMR spectroscopy, and the structure of 1 was determined by X-ray crystallography. Complex 1 reacts reversibly with dihydrogen to give Cp*2Ti(H)SH (6) and py. Reaction of 1 with HD gives an equilibrium mixture of Cp*2Ti(D)SH and Cp*2Ti(H)SD; H2 and D2 are not formed in this reaction. 1D 1H NMR magnetization transfer spectra and 2D EXSY 1H NMR spectra of 6 in the presence of H2 show that in solution the H2, hydride, and hydrosulfido hydrogen atoms exchange. A four-center mechanism for this exchange is proposed. The EXSY studies show that the Ti–H and S–H hydrogens exchange with each other more rapidly than either of those hydrogens exchanges with external H2. A transient dihydrogen complex intermediate is proposed to explain this observation. The infrared spectrum of 6 shows an absorption assigned to the Ti–H stretching mode at 1591 cm−1 that shifts upon deuteration to 1154 cm−1. Reaction of 1 with trimethylsilane, diethylsilane, or dimethylsilane gives Cp*2-Ti(H)SSiMe3 (7), Cp*2Ti(H)SSiHEt2 (8), or Cp*2Ti(H)SSiHMe2 (9), respectively. The isotope effect for the reaction producing 7 has been measured, and a mechanism is proposed. Treatment of 1 with an additional equivalent of S8 results in the formation of the disulfide Cp*2Ti(S2) (4). Acetylene inserts into the Ti–S bond of 4 to produce the vinyl disulfide complex 5. The structures of 4 and 5 have been determined by X-ray diffraction. Compound 4 reacts with 2 in the presence of py to produce 1. Phosphines react with 4 in the presence of H2 to provide 6 and the corresponding phosphine sulfide. Reaction of hydrogen with 4 gives Cp*2-Ti(SH)2 (3). The reactions of 1 and 4 with dihydrogen provide a model for possible mechanisms of H2

  16. H2S exposure elicits differential expression of candidate genes in fish adapted to sulfidic and non-sulfidic environments.

    Science.gov (United States)

    Tobler, Michael; Henpita, Chathurika; Bassett, Brandon; Kelley, Joanna L; Shaw, Jennifer H

    2014-09-01

    Disentangling the effects of plasticity, genetic variation, and their interactions on organismal responses to environmental stressors is a key objective in ecological physiology. We quantified the expression of five candidate genes in response to hydrogen sulfide (H2S) exposure in fish (Poecilia mexicana, Poeciliidae) from a naturally sulfide-rich environment as well as an ancestral, non-sulfidic population to test for constitutive and environmentally dependent population differences in gene expression patterns. Common garden raised individuals that had never encountered environmental H2S during their lifetime were subjected to short or long term H2S exposure treatments or respective non-sulfidic controls. The expression of genes involved in responses to H2S toxicity (cytochrome c oxidase, vascular endothelial growth factor, and cytochrome P450-2J6), H2S detoxification (sulfide:quinone oxidoreductase), and endogenous H2S production (cystathionine γ lyase) was determined in both gill and liver tissues by real time PCR. The results indicated complex changes in expression patterns that--depending on the gene--not only differed between organs and populations, but also on the type of H2S exposure. Populations differences, both constitutive and H2S exposure dependent (i.e., plastic), in gene expression were particularly evident for sulfide:quinone oxidoreductase, vascular endothelial growth factor, and to a lesser degree for cytochrome P450-2J6. Our study uncovered putatively adaptive modifications in gene regulation that parallel previously documented adaptive changes in phenotypic traits.

  17. Mitochondria and sulfide: a very old story of poisoning, feeding, and signaling?

    Science.gov (United States)

    Bouillaud, Frédéric; Blachier, François

    2011-07-15

    Sulfide is a molecule with toxicity comparable to that of cyanide. It inhibits mitochondrial cytochrome oxidase at submicromolar concentrations. However, at even lower concentrations, sulfide is a substrate for the mitochondrial electron transport chain in mammals, and is comparable to succinate. This oxidation involves a sulfide quinone reductase. Sulfide is thus oxidized before reaching a toxic concentration, which explains why free sulfide concentrations are very low in mammals, even though sulfide is constantly released as a result of cellular metabolism. It has been suggested that sulfide has signaling properties in mammals like two other gases, NO and CO, which are also cytochrome oxidase inhibitors. The oxidation of sulfide by mitochondria creates further complexity in the description/use of sulfide signaling in mammals. In fact, in the many studies reported in the literature, the sulfide concentrations that have been used were well within the range that affects mitochondrial activity. This review focuses on the relevance of sulfide bioenergetics to sulfide biology and discusses the case of colonocytes, which are routinely exposed to higher sulfide concentrations. Finally, we offer perspectives for future studies on the relationship between the two opposing aspects of this Janus-type molecule, sulfide.

  18. Controls on Weathering of Pyrrhotite in a Low-Sulfide, Granitic Mine-Waste Rock in the Canadian Arctic

    Science.gov (United States)

    Langman, J. B.; Holland, S.; Sinclair, S.; Blowes, D.

    2013-12-01

    Increased environmental risk is incurred with expansion of mineral extraction in the Arctic. A greater understanding of geochemical processes associated with hard-rock mining in this cold climate is needed to evaluate and mitigate these risks. A laboratory and in-situ experiment was conducted to examine mineral weathering and the generation of acid rock drainage in a low-sulfide, run-of-mine waste rock in an Arctic climate. Rock with different concentrations of sulfides (primarily pyrrhotite [Fe7S8] containing small amounts of Co and Ni) and carbonates were weathered in the laboratory and in-situ, large-scale test piles to examine leachate composition and mineral weathering. The relatively larger sulfide-containing rock produced sufficient acid to overcome carbonate buffering and produced a declining pH environment with concomitant release of SO4, Fe, Co, and Ni. Following carbonate consumption, aluminosilicate buffering stabilized the pH above 4 until a reduction in acid generation. Results from the laboratory experiment assisted in determining that after consumption of 1.6 percent of the total sulfide, the larger sulfide-concentration test pile likely is at an internal steady-state or maximal weathering rate after seven years of precipitation input and weathering that is controlled by an annual freeze-thaw cycle. Further weathering of the test pile should be driven by external factors of temperature and precipitation in this Arctic, semi-arid region instead of internal factors of wetting and non-equilibrium buffering. It is predicted that maximal weathering will continue until at least 20 percent of the total sulfide is consumed. Using the identified evolution of sulfide consumption in this Arctic climate, a variable rate factor can now be assessed for the possible early evolution and maximal weathering of larger scale waste-rock piles and seasonal differences because of changes in the volume of a waste-rock pile undergoing active weathering due to the freeze

  19. Anisotropic Optical Properties of Layered Germanium Sulfide

    CERN Document Server

    Tan, Dezhi; Wang, Feijiu; Mohamed, Nur Baizura; Mouri, Shinichiro; Sandhaya, Koirala; Zhang, Wenjing; Miyauchi, Yuhei; Ohfuchi, Mari; Matsuda, Kazunari

    2016-01-01

    Two-dimensional (2D) layered materials, transition metal dichalcogenides and black phosphorus, have attracted much interest from the viewpoints of fundamental physics and device applications. The establishment of new functionalities in anisotropic layered 2D materials is a challenging but rewarding frontier, owing to their remarkable optical properties and prospects for new devices. Here, we report the anisotropic optical properties of layered 2D monochalcogenide of germanium sulfide (GeS). Three Raman scattering peaks corresponding to the B3g, A1g, and A2g modes with strong polarization dependence are demonstrated in the GeS flakes, which validates polarized Raman spectroscopy as an effective method for identifying the crystal orientation of anisotropic layered GeS. Photoluminescence (PL) is observed with a peak at around 1.66 eV that originates from the direct optical transition in GeS at room temperature. Moreover, determination of the polarization dependent characteristics of the PL and absorption reveals...

  20. Subnanometer Thin β-Indium Sulfide Nanosheets.

    Science.gov (United States)

    Acharya, Shinjita; Sarkar, Suresh; Pradhan, Narayan

    2012-12-20

    Nanosheets are a peculiar kind of nanomaterials that are grown two-dimensionally over a micrometer in length and a few nanometers in thickness. Wide varieties of inorganic semiconductor nanosheets are already reported, but controlling the crystal growth and tuning their thickness within few atomic layers have not been yet explored. We investigate here the parameters that determine the thickness and the formation mechanism of subnanometer thin (two atomic layers) cubic indium sulfide (In2S3) nanosheets. Using appropriate reaction condition, the growth kinetics is monitored by controlling the decomposition rate of the single source precursor of In2S3 as a function of nucleation temperature. The variation in the thickness of the nanosheets along the polar [111] direction has been correlated with the rate of evolved H2S gas, which in turn depends on the rate of the precursor decomposition. In addition, it has been observed that the thickness of the In2S3 nanosheets is related to the nucleation temperature.

  1. Detection of thiol modifications by hydrogen sulfide.

    Science.gov (United States)

    Williams, E; Pead, S; Whiteman, M; Wood, M E; Wilson, I D; Ladomery, M R; Teklic, T; Lisjak, M; Hancock, J T

    2015-01-01

    Hydrogen sulfide (H2S) is an important gasotransmitter in both animals and plants. Many physiological events, including responses to stress, have been suggested to involve H2S, at least in part. On the other hand, numerous responses have been reported following treatment with H2S, including changes in the levels of antioxidants and the activities of transcription factors. Therefore, it is important to understand and unravel the events that are taking place downstream of H2S in signaling pathways. H2S is known to interact with other reactive signaling molecules such as reactive oxygen species (ROS) and nitric oxide (NO). One of the mechanisms by which ROS and NO have effects in a cell is the modification of thiol groups on proteins, by oxidation or S-nitrosylation, respectively. Recently, it has been reported that H2S can also modify thiols. Here we report a method for the determination of thiol modifications on proteins following the treatment with biological samples with H2S donors. Here, the nematode Caenorhabditis elegans is used as a model system but this method can be used for samples from other animals or plants.

  2. Hydrogen Sulfide and Cellular Redox Homeostasis

    Directory of Open Access Journals (Sweden)

    Zhi-Zhong Xie

    2016-01-01

    Full Text Available Intracellular redox imbalance is mainly caused by overproduction of reactive oxygen species (ROS or weakness of the natural antioxidant defense system. It is involved in the pathophysiology of a wide array of human diseases. Hydrogen sulfide (H2S is now recognized as the third “gasotransmitters” and proved to exert a wide range of physiological and cytoprotective functions in the biological systems. Among these functions, the role of H2S in oxidative stress has been one of the main focuses over years. However, the underlying mechanisms for the antioxidant effect of H2S are still poorly comprehended. This review presents an overview of the current understanding of H2S specially focusing on the new understanding and mechanisms of the antioxidant effects of H2S based on recent reports. Both inhibition of ROS generation and stimulation of antioxidants are discussed. H2S-induced S-sulfhydration of key proteins (e.g., p66Shc and Keap1 is also one of the focuses of this review.

  3. Hydrogen Sulfide and Cellular Redox Homeostasis

    Science.gov (United States)

    Xie, Zhi-Zhong; Liu, Yang; Bian, Jin-Song

    2016-01-01

    Intracellular redox imbalance is mainly caused by overproduction of reactive oxygen species (ROS) or weakness of the natural antioxidant defense system. It is involved in the pathophysiology of a wide array of human diseases. Hydrogen sulfide (H2S) is now recognized as the third “gasotransmitters” and proved to exert a wide range of physiological and cytoprotective functions in the biological systems. Among these functions, the role of H2S in oxidative stress has been one of the main focuses over years. However, the underlying mechanisms for the antioxidant effect of H2S are still poorly comprehended. This review presents an overview of the current understanding of H2S specially focusing on the new understanding and mechanisms of the antioxidant effects of H2S based on recent reports. Both inhibition of ROS generation and stimulation of antioxidants are discussed. H2S-induced S-sulfhydration of key proteins (e.g., p66Shc and Keap1) is also one of the focuses of this review. PMID:26881033

  4. Mercury Sulfide Dimorphism in Thioarsenate Glasses.

    Science.gov (United States)

    Kassem, M; Sokolov, A; Cuisset, A; Usuki, T; Khaoulani, S; Masselin, P; Le Coq, D; Neuefeind, J C; Feygenson, M; Hannon, A C; Benmore, C J; Bychkov, E

    2016-06-16

    Crystalline mercury sulfide exists in two drastically different polymorphic forms in different domains of the P,T-diagram: red chain-like insulator α-HgS, stable below 344 °C, and black tetrahedral narrow-band semiconductor β-HgS, stable at higher temperatures. Using pulsed neutron and high-energy X-ray diffraction, we show that these two mercury bonding patterns are present simultaneously in mercury thioarsenate glasses HgS-As2S3. The population and interconnectivity of chain-like and tetrahedral dimorphous forms determine both the structural features and fundamental glass properties (thermal, electronic, etc.). DFT simulations of mercury species and RMC modeling of high-resolution diffraction data provide additional details on local Hg environment and connectivity implying the (HgS2/2)m oligomeric chains (1 ≤ m ≤ 6) are acting as a network former while the HgS4/4-related mixed agglomerated units behave as a modifier.

  5. The effects of varying humidity on copper sulfide film formation.

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Thomas Michael; Missert, Nancy A.; Barbour, John Charles; Sullivan, John Patrick; Copeland, Robert Guild; Campin, Michael J. (International Sematech, Austin, TX)

    2004-02-01

    Detailed experiments involving extensive high resolution transmission electron microscopy (TEM) revealed significant microstructural differences between Cu sulfides formed at low and high relative humidity (RH). It was known from prior experiments that the sulfide grows linearly with time at low RH up to a sulfide thickness approaching or exceeding one micron, while the sulfide initially grows linearly with time at high RH then becomes sub-linear at a sulfide thickness less than about 0.2 microns, with the sulfidation rate eventually approaching zero. TEM measurements of the Cu2S morphology revealed that the Cu2S formed at low RH has large sized grains (75 to greater than 150 nm) that are columnar in structure with sharp, abrupt grain boundaries. In contrast, the Cu2S formed at high RH has small equiaxed grains of 20 to 50 nm in size. Importantly, the small grains formed at high RH have highly disordered grain boundaries with a high concentration of nano-voids. Two-dimensional diffusion modeling was performed to determine whether the existence of localized source terms at the Cu/Cu2S interface could be responsible for the suppression of Cu sulfidation at long times at high RH. The models indicated that the existence of static localized source terms would not predict the complete suppression of growth that was observed. Instead, the models suggest that the diffusion of Cu through Cu2S becomes restricted during Cu2S formation at high RH. The leading speculation is that the extensive voiding that exists at grain boundaries in this material greatly reduces the flux of Cu between grains, leading to a reduction in the rate of sulfide film formation. These experiments provide an approach for adding microstructural information to Cu sulfidation rate computer models. In addition to the microstructural studies, new micro-patterned test structures were developed in this LDRD to offer insight into the point defect structure of Cu2S and to permit measurement of surface reaction

  6. Assessing the Role of Iron Sulfides in the Long Term Sequestration of Uranium by Sulfate-Reducing Bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, Kim F.; Bi, Yuqiang; Carpenter, Julian; Hyng, Sung Pil; Rittmann, Bruce E.; Zhou, Chen; Vannela, Raveender; Davis, James A.

    2014-01-01

    iron was poorly crystalline. At UM, laboratory-scale reactor studies were performed to assess the potential for the predominant abiotic reductants formed under sulfate reducing conditions (SRCs) to: (1) reduce U(VI) in contaminated groundwater sediments), and (2) inhibit the re-oxidation of U(IV) species, and in particular, uraninite (UO2(s)). Under SRCs, mackinawite and aqueous sulfide are the key reductants expected to form. To assess their potential for abiotic reduction of U(VI) species, a series of experiments were performed in which either FeS or S(-II) was added to solutions of U(VI), with the rates of conversion to U(IV) solids monitored as a function of pH, and carbonate and calcium concentration. In the presence of FeS and absence of oxygen or carbonate, U(IV) was completely reduced uraninite. S(-II) was also found to be an effective reductant of aqueous phase U(VI) species and produced uraninite, with the kinetics and extent of reduction depending on geochemical conditions. U(VI) reduction to uraninite was faster under higher S(-II) concentrations but was slowed by an increase in the dissolved Ca or carbonate concentration. Rapid reduction of U(VI) occurred at circumneutral pH but virtually no reduction occurred at pH 10.7. In general, dissolved Ca and carbonate slowed abiotic U(VI) reduction by forming stable Ca-U(VI)-carbonate soluble complexes that are resistant to reaction with aqueous sulfide. To investigate the stability of U(IV) against re-oxidation in the presence of iron sulfides by oxidants in simulated groundwater environments, and to develop a mechanistic understanding the controlling redox processes, continuously-mixed batch reactor (CMBR) and flow-through reactor (CMFR) studies were performed at UM. In these studies a series of experiments were conducted under various oxic groundwater conditions to examine the effectiveness of FeS as an oxygen scavenger to retard UO2 dissolution. The results indicate that FeS is an effective oxygen scavenger

  7. Carbonyl sulfide and dimethyl sulfide exchange between lawn and the atmosphere

    Science.gov (United States)

    Geng, Chunmei; Mu, Yujing

    2004-06-01

    The exchange of carbonyl sulfide (COS) between lawn and the atmosphere was investigated by using a static enclosure under natural field conditions. The results indicated that the lawn acted as a sink for atmospheric COS and a source of dimethyl sulfide (DMS). The exchange fluxes of COS and DMS ranged between -3.24 pmol m-2 s-1 and -94.52 pmol m-2 s-1, and between 0 and 3.14 pmol m-2 s-1, respectively. The lawn was capable of continuously absorbing COS in nighttime as well as in daytime. The COS fluxes depended strongly on the ambient COS mixing ratios. The dependency of DMS emission fluxes on temperature was observed in November 2002. Soil also acted as a sink for COS during our study. However, the COS exchange fluxes of the lawn were much higher than that of the soil. The average COS and DMS fluxes were much higher in spring than in autumn and in summer. The daytime vertical profiles of COS also indicated that the lawn acted as a net sink for COS.

  8. Trace metal behaviour in riverine sediments: Role of organic matter and sulfides

    Energy Technology Data Exchange (ETDEWEB)

    Charriau, Adeline; Lesven, Ludovic [Universite Lille 1 Sciences et Technologies, Laboratoire Geosystemes (FRE-CNRS 3298), 59655 Villeneuve d' Ascq (France); Gao Yue; Leermakers, Martine; Baeyens, Willy [Department of Analytical and Environmental Chemistry (ANCH), Vrije Universiteit Brussel (VUB), B-1050 Brussels (Belgium); Ouddane, Baghdad [Universite Lille 1 Sciences et Technologies, Laboratoire Geosystemes (FRE-CNRS 3298), 59655 Villeneuve d' Ascq (France); Billon, Gabriel, E-mail: gabriel.billon@univ-lille1.fr [Universite Lille 1 Sciences et Technologies, Laboratoire Geosystemes (FRE-CNRS 3298), 59655 Villeneuve d' Ascq (France)

    2011-01-15

    Graphical abstract: Experimental and modelling approach on trace metal fate in anoxic sediments. Display Omitted Research highlights: {yields} Experimental and modelling approach on trace metals fate in anoxic sediments. {yields} Organic matter and sulphides compete for the binding of trace metals. {yields} Efficient scavenging of trace metals in sulphide minerals. {yields} Dissolved organic matter increases the solubility of trace metals in pore waters. {yields} Similar lability of trace metals in pore waters and sediment particles. - Abstract: Three sediment cores were collected in the Scheldt, Lys and Spiere canals, which drain a highly populated and industrialized area in Western Europe. The speciation and the distribution of trace metals in pore waters and sediment particles were assessed through a combination of computational and experimental techniques. The concentrations of dissolved major and trace elements (anions, cations, sulfides, dissolved organic C, Cd, Co, Fe, Mn, Ni, Pb and Zn) were used to calculate the thermodynamic equilibrium speciation in pore waters and to evaluate the saturation of minerals (Visual Minteq software). A sequential extraction procedure was applied on anoxic sediment particles in order to assess the main host phases of trace elements. Manganese was the most labile metal in pore waters and was mainly associated with carbonates in particles. In contrast, a weak affinity of Cd, Co, Ni, Pb and Zn with carbonates was established because: (1) a systematic under-saturation was noticed in pore waters and (2) less than 10% of these elements were extracted in the exchangeable and carbonate sedimentary fraction. In the studied anoxic sediments, the mobility and the lability of trace metals, apart from Mn, seemed to be controlled through the competition between sulfidic and organic ligands. In particular, the necessity of taking into account organic matter in the modelling of thermodynamic equilibrium was demonstrated for Cd, Ni, Zn and Pb

  9. Biogeochemical factors which regulate the formation and fate of sulfide in wetlands

    Science.gov (United States)

    Hines, Mark E.; Lyons, W. Berry; Gaudette, H. E.

    1985-01-01

    Coastal wetland areas occupy a small percentage of the terrestrial environment yet are extremely productive regions which support rapid rates of below ground bacterial activity. Wetlands appear to be significant as biogenic sources of gaseous sulfur, carbon, and nitrogen. These gases are important as tracers of man's activities, and they influence atmospheric chemistry. The interactions among wetland biogeochemical processes regulate the anaerobic production of reduced gases and influence the fate of these volatiles. Therefore, spatial and temporal variations in hydrology, salinity, temperature, and speciation and growth of vegetation affect the type and magnitude of gas emissions thus hindering predictive estimates of gas flux. The research is divided into two major parts, the first is the biogeochemical characterization of a selected tidal wetland area in terms of factors likely to regulate sulfide flux; the second is a direct measurement of gaseous sulfur flux as related to changes in these biogeochemical conditions. Variant factors affecting sulfide flux include the wetlands' tidal range, seasonal salinity, and other hydrological conditions, grass species and plant growth, soil composition, and microbial activity.

  10. Insights into the mechanism of the reaction between hydrogen sulfide and peroxynitrite.

    Science.gov (United States)

    Cuevasanta, Ernesto; Zeida, Ari; Carballal, Sebastián; Wedmann, Rudolf; Morzan, Uriel N; Trujillo, Madia; Radi, Rafael; Estrin, Darío A; Filipovic, Milos R; Alvarez, Beatriz

    2015-03-01

    Hydrogen sulfide and peroxynitrite are endogenously generated molecules that participate in biologically relevant pathways. A revision of the kinetic features of the reaction between peroxynitrite and hydrogen sulfide revealed a complex process. The rate constant of peroxynitrite decay, (6.65 ± 0.08) × 10(3) M(-1) s(-1) in 0.05 M sodium phosphate buffer (pH 7.4, 37°C), was affected by the concentration of buffer. Theoretical modeling suggested that, as in the case of thiols, the reaction is initiated by the nucleophilic attack of HS(-) on the peroxide group of ONOOH by a typical bimolecular nucleophilic substitution, yielding HSOH and NO2(-). In contrast to thiols, the reaction then proceeds to the formation of distinct products that absorb near 408 nm. Experiments in the presence of scavengers and carbon dioxide showed that free radicals are unlikely to be involved in the formation of these products. The results are consistent with product formation involving the reactive intermediate HSSH and its fast reaction with a second peroxynitrite molecule. Mass spectrometry and UV-Vis absorption spectra predictions suggest that at least one of the products is HSNO2 or its isomer HSONO.

  11. Gas phase recovery of hydrogen sulfide contaminated polymer electrolyte membrane fuel cells

    Science.gov (United States)

    Kakati, Biraj Kumar; Kucernak, Anthony R. J.

    2014-04-01

    The effect of hydrogen sulfide (H2S) on the anode of a polymer electrolyte membrane fuel cell (PEMFC) and the gas phase recovery of the contaminated PEMFC using ozone (O3) were studied. Experiments were performed on fuel cell electrodes both in an aqueous electrolyte and within an operating fuel cell. The ex-situ analyses of a fresh electrode; a H2S contaminated electrode (23 μmolH2S cm-2); and the contaminated electrode cleaned with O3 shows that all sulfide can be removed within 900 s at room temperature. Online gas analysis of the recovery process confirms the recovery time required as around 720 s. Similarly, performance studies of an H2S contaminated PEMFC shows that complete rejuvenation occurs following 600-900 s O3 treatment at room temperature. The cleaning process involves both electrochemical oxidation (facilitated by the high equilibrium potential of the O3 reduction process) and direct chemical oxidation of the contaminant. The O3 cleaning process is more efficient than the external polarization of the single cell at 1.6 V. Application of O3 at room temperature limits the amount of carbon corrosion. Room temperature O3 treatment of poisoned fuel cell stacks may offer an efficient and quick remediation method to recover otherwise inoperable systems.

  12. Review of the toxicology of carbonyl sulfide, a new grain fumigant.

    Science.gov (United States)

    Bartholomaeus, Andrew R; Haritos, Victoria S

    2005-12-01

    Carbonyl sulfide (COS) is a new grain fumigant which has been developed to replace methyl bromide, being phased out due to its ozone depletion properties, and to supplement phosphine gas which is experiencing increased insect resistance. Treatment of commodities with COS, a highly effective fumigant, results in residues that are near or indistinguishable to natural background levels of this compound. COS is a naturally occurring gas, being the predominant sulfur moiety in the atmosphere, occurs naturally in food and is a normal by-product of mammalian aerobic metabolism. COS has low acute inhalational toxicity but with a steep dose response curve; COS is neither genotoxic nor a developmental toxicant but does reversibly impair male fertility. Prolonged, repeated exposure to COS is likely to present similar neurotoxicity hazards to that of the structurally and toxicologically related compound carbon disulfide. Although the occupational risks presented by COS as a fumigant of bulk grain are significant, these are, as they have been for a considerable time for phosphine and methyl bromide, manageable by good occupational safety practices. Consideration may need to be given to scrubbing of ventilated COS and its breakdown product hydrogen sulfide, at the completion of fumigation to minimise worker and bystander exposure. In terms of classical regulatory toxicology studies, the available database for COS is deficient in many aspects and registration in most jurisdictions will depend on sound scientific argument built upon the totality of the existing scientific data as there are strong arguments supporting the registration of this compound.

  13. Global budget of atmospheric carbonyl sulfide: Temporal and spatial variations of the dominant sources and sinks

    Science.gov (United States)

    Kettle, A. J.; Kuhn, U.; von Hobe, M.; Kesselmeier, J.; Andreae, M. O.

    2002-11-01

    The spatial and temporal variability of the global fluxes of carbonyl sulfide (COS) is discussed together with possible implications for total column atmospheric COS loading. The input of COS into the atmosphere is calculated as the sum of all known direct sources of COS plus the conversion of carbon disulfide (CS2) and dimethyl sulfide (DMS) to COS by atmospheric oxidation processes. Recent models are used to predict COS, CS2, and DMS release from the oceans and COS uptake by soils, plants, and oceans. This forward approach to constructing global integrated COS fluxes has a large associated range of uncertainty. The best guess global annual-integrated COS net flux estimate does not differ from zero within the range of estimated uncertainty, consistent with the observed absence of long-term trends in atmospheric COS loading. Interestingly, the hemispheric time-dependent monthly fluxes are very close in phase for the Northern and Southern Hemispheres. The monthly variation of the Northern Hemisphere flux seems to be driven primarily by high COS vegetation uptake in summer, while the monthly variation of the Southern Hemisphere flux appears to be driven mostly by high oceanic fluxes of COS, CS2, and DMS in summer.

  14. Relationships between carbonyl sulfide (COS) and CO2 during leaf gas exchange.

    Science.gov (United States)

    Stimler, Keren; Montzka, Stephen A; Berry, Joseph A; Rudich, Yinon; Yakir, Dan

    2010-06-01

    *Carbonyl sulfide (COS) exchange in C(3) leaves is linked to that of CO(2), providing a basis for the use of COS as a powerful tracer of gross CO(2) fluxes between plants and the atmosphere, a critical element in understanding the response of the land biosphere to global change. *Here, we carried out controlled leaf-scale gas-exchange measurements of COS and CO(2) in representative C(3) plants under a range of light intensities, relative humidities and temperatures, CO(2) and COS concentrations, and following abscisic acid treatments. *No 'respiration-like' emission of COS or detectable compensation point, and no cross-inhibition effects between COS and CO(2) were observed. The mean ratio of COS to CO(2) assimilation flux rates, A(s)/A(c), was c. 1.4 pmol micromol(-1) and the leaf relative uptake (assimilation normalized to ambient concentrations, (A(s)/A(c))(C(a)(c)/C(a)(s))) was 1.6-1.7 across species and conditions, with significant deviations under certain conditions. Stomatal conductance was enhanced by increasing COS, which was possibly mediated by hydrogen sulfide (H(2)S) produced from COS hydrolysis, and a correlation was observed between A(s) and leaf discrimination against C(18)OO. *The results provide systematic and quantitative information necessary for the use of COS in photosynthesis and carbon-cycle research on the physiological to global scales.

  15. Evaluation of thiosulfate as a substitute for hydrogen sulfide in sour corrosion fatigue studies

    Science.gov (United States)

    Kappes, Mariano Alberto

    This work evaluates the possibility of replacing hydrogen sulfide (H 2S) with thiosulfate anion (S2O32- ) in sour corrosion fatigue studies. H2S increases the corrosion fatigue crack growth rate (FCGR) and can be present in carbon steel risers and flowlines used in off-shore oil production. Corrosion tests with gaseous H2S require special facilities with safety features, because H2S is a toxic and flammable gas. The possibility of replacing H2S with S2O32-, a non-toxic anion, for studying stress corrosion cracking of stainless and carbon steels in H2S solutions was first proposed by Tsujikawa et al. ( Tsujikawa et al., Corrosion, 1993. 49(5): p. 409-419). In this dissertation, Tsujikawa work will be extended to sour corrosion fatigue of carbon steels. H2S testing is often conducted in deareated condition to avoid oxygen reaction with sulfide that yields sulfur and to mimic oil production conditions. Nitrogen deareation was also adopted in S2O3 2- testing, and gas exiting the cell was forced through a sodium hydroxide trap. Measurements of the sulfide content of this trap were used to estimate the partial pressure of H2S in nitrogen, and Henry's law was used to estimate the content of H2S in the solution in the cell. H2S was produced by a redox reaction of S2O 32-, which required electrons from carbon steel corrosion. This reaction is spontaneous at the open circuit potential of steel. Therefore, H2S concentration was expected to be maximum at the steel surface, and this concentration was estimated by a mass balance analysis. Carbon steel specimens exposed to S2O32- containing solutions developed a film on their surface, composed by iron sulfide and cementite. The film was not passivating and a good conductor of electrons. Hydrogen permeation experiments proved that this film controls the rate of hydrogen absorption of steels exposed to thiosulfate containing solutions. The absorption of hydrogen in S2O3 2- solutions was compared with the absorption of hydrogen in

  16. Inhibition of the cystathionine-γ-lyase/hydrogen sulfide pathway in rat vascular smooth muscle cells by cobalt-60 gamma radiation

    Institute of Scientific and Technical Information of China (English)

    ZHONG Guang-zhen; YANG Xin-chun; JIA Li-ping; CHEN Feng-rong; CUI Ming

    2009-01-01

    Background Radiation is a promising treatment for in stent restenosis and restenosis following percutaneous transluminal coronary angioplasty, which has troubled interventional cardiologists for a long time. It inhibits neointima hyperplasia, vascular remodeling, and increases the mean luminal diameter. The mechanism of intracoronary brachytherapy for restenosis is not well understood. Endogenous gaseous transmitters including nitric oxide and carbon monoxide are closely related to restenosis. Hydrogen sulfide, a new endogenous gaseous transmitter, is able to inhibit the proliferation of vascular smooth muscle cells and vascular remodeling. This study aimed to clarify the effect of radiation on cystathionine-y-lyase/hydrogen sulfide pathway in rat smooth muscle cells.Methods We studied the effect of radiation on the cystathionine-γ-lyase/hydrogen sulfide pathway. Rat vascular smooth muscle cells were radiated with 60Co y at doses of 14 Gy and 25 Gy respectively. Then the mRNA level of cystathionine-γ-lyase was studied by quantitative reverse-transcription competitive polymerase chain reaction. Hydrogen sulfide concentration in culture medium was determined by methylene blue spectrophotometry. Cystathionine-γ-lyase activity in vascular smooth muscle cells was also studied.Results 60Co y radiation at a dose of 1 Gy did not affect the cystathionine-γ-lyase/hydrogen sulfide pathway significantly. However, 60Co y radiation at doses of 14 Gy and 25 Gy decreased the hydrogen sulfide synthesis by 21.9% (P <0.05) and 26.8% (P <0.01 ) respectively. At the same time, they decreased the cystathionine-γ-lyase activity by 15.1% (P <0.05) and 20.5% (P <0.01) respectively, and cystathionine-γ-lyase mRNA expression by 29.3% (P <0.01 ) and 38.2% (P <0.01) respectively.Conclusion Appropriate 60Co γ radiation inhibits the H2S synthesis by inhibiting the gene expression of cystathionine-γ-lyase and the cystathionine-y-lyase activity.

  17. Microbial control of hydrogen sulfide production in a porous medium

    Energy Technology Data Exchange (ETDEWEB)

    McInerney, M.J.; Wofford, N.Q. [Univ. of Oklahoma, Norman, OK (United States); Sublette, K.L. [Univ. of Tulsa, OK (United States)

    1996-12-31

    The ability of a sulfide- and glutaraldehyde-tolerant strain of Thiobacillus denitrificans (strain F) to control sulfide production in an experimental system of cores and formation water from the Redfield, Iowa natural gas storage facility was investigated. A stable, sulfide-producing biofilm was established in two separate core systems, one of which was inoculated with strain F, and the other core system (control) was treated in an identical manner, but was not inoculated with strain F. When formation water with 10 mM acetate and 5mM nitrate was injected into both core systems, the effluent sulfide concentrations in the control core system ranged from 200-460 {mu}M. In the test core system inoculated with strain F, the effluent sulfide concentrations were lower, ranging from 70-110 {mu}M. In order to determine whether strain F could control sulfide production under optimal conditions for sulfate-reducing bacteria, the electron donor was changed to lactate, and inorganic nutrients (nitrogen and phosphate sources) were added to the formation water. When nutrient-supplemented formation water with 3.1 mM lactate and 10 mM nitrate was used, the effluent sulfide concentrations of the control core system initially increased to about 3800 pM, and then decreased to about 1100 {mu}M after 5 wk. However, in the test core system inoculated with strain F, the effluent sulfide concentrations were much lower, 160-330 {mu}M. Nitrate consumption (5 mM) and high concentrations (101-1011 cells/mL) of strain F were detected in the test core system. An accumulation of biomass occurred in the influent lines during 2 mo of continuous operation, but only a small increase in injection pressure was observed. These studies showed that inoculation with strain F was needed for effective control of sulfide production, and that significant plugging or loss of injectivity owing to microbial inoculation did not occur. 7 refs., 3 figs., 1 tab.

  18. Species-specific enzymatic tolerance of sulfide toxicity in plant roots.

    Science.gov (United States)

    Martin, Nicole M; Maricle, Brian R

    2015-03-01

    Toxic effects of sulfide come from a poisoning of a number of enzymes, especially cytochrome c oxidase, which catalyzes the terminal step in mitochondrial aerobic respiration. Despite this, some estuarine plants live in sulfide-rich sediments. We hypothesized estuarine and flooding-tolerant species might be more tolerant of sulfide compared to upland species, and this was tested by measures of root cytochrome c oxidase and alcohol dehydrogenase activities in extracts exposed to sulfide. Enzyme activities were measured in 0, 5, 10, 15, and 20 μM sodium sulfide, and compared among 17 species of plants. Activities of alcohol dehydrogenase and cytochrome c oxidase were both reduced by increasing sulfide concentration, but cytochrome c oxidase was more sensitive to sulfide compared to alcohol dehydrogenase. Activities of cytochrome c oxidase were reduced to near zero at 5-10 μM sulfide whereas alcohol dehydrogenase activities were only reduced by about 50% at 10 μM sulfide. All species were sensitive to increasing sulfide, but to different degrees. Cytochrome c oxidase in flooding-sensitive species was decreased to near zero activity at 5 μM sulfide, whereas activities in some flooding-tolerant species were still detectable until 15 μM sulfide. Cytochrome c oxidase activities in some estuarine species were low even in the absence of sulfide, perhaps an adaptation to avoid sulfide vulnerability in their native, sulfide-rich habitat. This illustrates the potent metabolic effects of sulfide, and this is the first demonstration of varying sensitivities of cytochrome c oxidase to sulfide across organisms, making these data of novel importance.

  19. Aspects of the bottom sediment of Lake Nakaumi and Honjo area ~ featuring with organic matter and the Sulfides ~

    Science.gov (United States)

    Shinohara, R.

    2015-12-01

    Lake Nakaumi is a brackish water located at southwest Japan. Seawater from the Sea of Japan inflows through Sakai-strait, and river water flows through the Oohashi River into this lake. Lake Nakaumi is characterized with hypoxic and/or anoxic condition of bottom water derived with the distinct stratification of salinity in summer season. In this lake, a public project had been carried out for land reclamation since 1963. Honjo Area located to the north part of Lake Nakaumi, was semi-separated from Lake Nakaumi by reclamation dikes constructed for this project at 1981. However, this public project was aborted with the change of social conditions. To the effective utilization of the area, the partial removal of dike was carried out. Seawater from Sakai-strait flows directly into Honjo Area again. Environmental change of the lake is expected by this inflow of the seawater in Lake Nakaumi and Honjo Area after this restoration. It is well known that the surface sediment reflects the environment of lake bottom. The organic matter and the sulfides in sediment are good indicators of sedimentation environment. In this study, we analyzed them by several methods and grasped the bottom environment of both areas after the removal of dikes. We examined the impact of the restoration to both areas by comparing the observations with the past data. Surface sediment samples in Lake Nakaumi and Honjo Area were obtained at 77 and 40 stations, respectively. We collected surface sediment (about 1cm) were for each station, and analyzed total organic carbon (TOC) and total nitrogen (TN) as organic matter, and hydrogen sulfide (H2S) in pore water, total sulfide (TS) and acid volatile sulfide (AVS) as sulfides. TOC contents of Lake Nakaumi and Honjo Area range within 0.0-5.1% and 0.2-4.9%, respectively. TN contents range within 0.0-0.6 % and 0.1-0.6 %. TS contents range within 0.1-2.6% and 0.0-2.0 %. H2S contents range within 0.3-119.0 ppm and 0.5-140.4 ppm. AVS contents range within 0

  20. Influence of dissolved organic matter on the complexation of mercury under sulfidic conditions.

    Science.gov (United States)

    Miller, Carrie L; Mason, Robert P; Gilmour, Cynthia C; Heyes, Andrew

    2007-04-01

    The complexation of Hg under sulfidic conditions influences its bioavailability for microbial methylation. Neutral dissolved Hg-sulfide complexes are readily available to Hg-methylating bacteria in culture, and thermodynamic models predict that inorganic Hg-sulfide complexes dominate dissolved Hg speciation under natural sulfidic conditions. However, these models have not been validated in the field. To examine the complexation of Hg in natural sulfidic waters, octanol/water partitioning methods were modified for use under environmentally relevant conditions, and a centrifuge ultrafiltration technique was developed. These techniques demonstrated much lower concentrations of dissolved Hg-sulfide complexes than predicted. Furthermore, the study revealed an interaction between Hg, dissolved organic matter (DOM), and sulfide that is not captured by current thermodynamic models. Whereas Hg forms strong complexes with DOM under oxic conditions, these complexes had not been expected to form in the presence of sulfide because of the stronger affinity of Hg for sulfide relative to its affinity for DOM. The observed interaction between Hg and DOM in the presence of sulfide likely involves the formation of a DOM-Hg-sulfide complex or results from the hydrophobic partitioning of neutral Hg-sulfide complexes into the higher-molecular-weight DOM. An understanding of the mechanism of this interaction and determination of complexation coefficients for the Hg-sulfide-DOM complex are needed to adequately assess how our new finding affects Hg bioavailability, sorption, and flux.

  1. Interaction of hydrogen sulfide with ion channels.

    Science.gov (United States)

    Tang, Guanghua; Wu, Lingyun; Wang, Rui

    2010-07-01

    1. Hydrogen sulfide (H(2)S) is a signalling gasotransmitter. It targets different ion channels and receptors, and fulfils its various roles in modulating the functions of different systems. However, the interaction of H(2)S with different types of ion channels and underlying molecular mechanisms has not been reviewed systematically. 2. H(2)S is the first identified endogenous gaseous opener of ATP-sensitive K(+) channels in vascular smooth muscle cells. Through the activation of ATP-sensitive K(+) channels, H(2)S lowers blood pressure, protects the heart from ischemia and reperfusion injury, inhibits insulin secretion in pancreatic beta cells, and exerts anti-inflammatory, anti-nociceptive and anti-apoptotic effects. 3. H(2)S inhibited L-type Ca(2+) channels in cardiomyocytes but stimulated the same channels in neurons, thus regulating intracellular Ca(2+) levels. H(2)S activated small and medium conductance K(Ca) channels but its effect on BK(Ca) channels has not been consistent. 4. H(2)S-induced hyperalgesia and pro-nociception seems to be related to the sensitization of both T-type Ca(2+) channels and TRPV(1) channels. The activation of TRPV(1) and TRPA(1) by H(2)S is believed to result in contraction of nonvascular smooth muscles and increased colonic mucosal Cl(-) secretion. 5. The activation of Cl(-) channel by H(2)S has been shown as a protective mechanism for neurons from oxytosis. H(2)S also potentiates N-methyl-d-aspartic acid receptor-mediated currents that are involved in regulating synaptic plasticity for learning and memory. 6. Given the important modulatory effects of H(2)S on different ion channels, many cellular functions and disease conditions related to homeostatic control of ion fluxes across cell membrane should be re-evaluated.

  2. Hydrogen sulfide and nervous system regulation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Cheng-fang; TANG Xiao-qing

    2011-01-01

    Objective This review discusses the current status and progress in studies on the roles of hydrogen sulfide (H2S) in regulation of neurotoxicity,neuroprotection,and neuromodulator,as well as its therapeutic potential for neurodegenerative disorders.Data sources The data used in this review were mainly from Medline and PubMed published in English from 2001 to August 2011.The search terms were “hydrogen sulfide”,“neuron”,and “neurodegenerative disorders”.Study selection Articles regarding the regulation of neuronal function,the protection against neuronal damage and neurological diseases,and their possible cellular and molecular mechanisms associated with H2S were selected.Results The inhibited generation of endogenous H2S is implicated in 1-methy-4-phenylpyridinium ion,6-OHDA,and homocysteine-triggered neurotoxicity.H2S elicits neuroprotection in Alzheimer's disease and Parkinson's disease models as well as protecting neurons against oxidative stress,ischemia,and hypoxia-induced neuronal death.H2S offers anti-oxidant,anti-inflammatory and anti-apoptotic effects,as well as activates ATP-sensitive potassium channels and cystic fibrosis transmembrane conductance regulator Cl- channels.H2S regulates the long-term potentiation (LTP) and GABAB receptors in the hippocampus,as well as intracellular calcium and pH homeostasis in neurons and glia cells.Conclusions These articles suggest that endogenous H2S may regulate the toxicity of neurotoxin.H2S not only acts as a neuroprotectant but also serves as a novel neuromodulator.

  3. Electrical properties of seafloor massive sulfides

    Science.gov (United States)

    Spagnoli, Giovanni; Hannington, Mark; Bairlein, Katharina; Hördt, Andreas; Jegen, Marion; Petersen, Sven; Laurila, Tea

    2016-06-01

    Seafloor massive sulfide (SMS) deposits are increasingly seen as important marine metal resources for the future. A growing number of industrialized nations are involved in the surveying and sampling of such deposits by drilling. Drill ships are expensive and their availability can be limited; seabed drill rigs are a cost-effective alternative and more suitable for obtaining cores for resource evaluation. In order to achieve the objectives of resource evaluations, details are required of the geological, mineralogical, and physical properties of the polymetallic deposits and their host rocks. Electrical properties of the deposits and their ore minerals are distinct from their unmineralized host rocks. Therefore, the use of electrical methods to detect SMS while drilling and recovering drill cores could decrease the costs and accelerate offshore operations by limiting the amount of drilling in unmineralized material. This paper presents new data regarding the electrical properties of SMS cores that can be used in that assessment. Frequency-dependent complex electrical resistivity in the frequency range between 0.002 and 100 Hz was examined in order to potentially discriminate between different types of fresh rocks, alteration and mineralization. Forty mini-cores of SMS and unmineralized host rocks were tested in the laboratory, originating from different tectonic settings such as the intermediate-spreading ridges of the Galapagos and Axial Seamount, and the Pacmanus back-arc basin. The results indicate that there is a clear potential to distinguish between mineralized and non-mineralized samples, with some evidence that even different types of mineralization can be discriminated. This could be achieved using resistivity magnitude alone with appropriate rig-mounted electrical sensors. Exploiting the frequency-dependent behavior of resistivity might amplify the differences and further improve the rock characterization.

  4. Chemical dosing for sulfide control in Australia: An industry survey.

    Science.gov (United States)

    Ganigue, Ramon; Gutierrez, Oriol; Rootsey, Ray; Yuan, Zhiguo

    2011-12-01

    Controlling sulfide (H(2)S) production and emission in sewer systems is critical due to the corrosion and malodour problems that sulfide causes. Chemical dosing is one of the most commonly used measures to mitigate these problems. Many chemicals have been reported to be effective for sulfide control, but the extent of success varies between chemicals and is also dependent on how they are applied. This industry survey aims to summarise the current practice in Australia with the view to assist the water industry to further improve their practices and to identify new research questions. Results showed that dosing is mainly undertaken in pressure mains. Magnesium hydroxide, sodium hydroxide and nitrate are the most commonly used chemicals for sewers with low flows. In comparison, iron salts are preferentially used for sulfide control in large systems. The use of oxygen injection has declined dramatically in the past few years. Chemical dosing is mainly conducted at wet wells and pumping stations, except for oxygen, which is injected into the pipe. The dosing rates are normally linked to the control mechanisms of the chemicals and the dosing locations, with constant or profiled dosing rates usually applied. Finally, key opportunities for improvement are the use of mathematical models for the selection of chemicals and dosing locations, on-line dynamic control of the dosing rates and the development of more cost-effective chemicals for sulfide control.

  5. Do garlic-derived allyl sulfides scavenge peroxyl radicals?

    Science.gov (United States)

    Amorati, Riccardo; Pedulli, Gian Franco

    2008-03-21

    The chain-breaking antioxidant activities of two garlic-derived allyl sulfides, i.e. diallyl disulfide (1), the main component of steam-distilled garlic oil, and allyl methyl sulfide (3) were evaluated by studying the thermally initiated autoxidation of cumene or styrene in their presence. Although the rate of cumene oxidation was reduced by addition of both 1 and 3, the dependence on the concentration of the two sulfides could not be explained on the basis of the classic antioxidant mechanism as with phenolic antioxidants. The rate of oxidation of styrene, on the other hand, did not show significant changes upon addition of either 1 or 3. This unusual behaviour was explained in terms of the co-oxidant effect, consisting in the decrease of the autoxidation rate of a substrate forming tertiary peroxyl radicals (i.e. cumene) upon addition of little amounts of a second oxidizable substrate giving rise instead to secondary peroxyl radicals. The relevant rate constants for the reaction of ROO(.) with 1 and 3 were measured as 1.6 and 1.0 M(-1) s(-1), respectively, fully consistent with the H-atom abstraction from substituted sulfides. It is therefore concluded that sulfides 1 and 3 do not scavenge peroxyl radicals and therefore cannot be considered chain-breaking antioxidants.

  6. Solubility and permeation of hydrogen sulfide in lipid membranes.

    Directory of Open Access Journals (Sweden)

    Ernesto Cuevasanta

    Full Text Available Hydrogen sulfide (H(2S is mainly known for its toxicity but has recently been shown to be produced endogenously in mammalian tissues and to be associated with physiological regulatory functions. To better understand the role of biomembranes in modulating its biological distribution and effects; we measured the partition coefficient of H(2S in models of biological membranes. The partition coefficients were found to be 2.1±0.2, 1.9±0.5 and 2.0±0.6 in n-octanol, hexane and dilauroylphosphatidylcholine liposome membranes relative to water, respectively (25°C. This two-fold higher concentration of H(2S in the membrane translates into a rapid membrane permeability, P(m = 3 cm s(-1. We used a mathematical model in three dimensions to gain insight into the diffusion of total sulfide in tissues. This model shows that the sphere of action of sulfide produced by a single cell expands to involve more than 200 neighboring cells, and that the resistance imposed by lipid membranes has a significant effect on the diffusional spread of sulfide at pH 7.4, increasing local concentrations. These results support the role of hydrogen sulfide as a paracrine signaling molecule and reveal advantageous pharmacokinetic properties for its therapeutic applications.

  7. Solubility and permeation of hydrogen sulfide in lipid membranes.

    Science.gov (United States)

    Cuevasanta, Ernesto; Denicola, Ana; Alvarez, Beatriz; Möller, Matías N

    2012-01-01

    Hydrogen sulfide (H(2)S) is mainly known for its toxicity but has recently been shown to be produced endogenously in mammalian tissues and to be associated with physiological regulatory functions. To better understand the role of biomembranes in modulating its biological distribution and effects; we measured the partition coefficient of H(2)S in models of biological membranes. The partition coefficients were found to be 2.1±0.2, 1.9±0.5 and 2.0±0.6 in n-octanol, hexane and dilauroylphosphatidylcholine liposome membranes relative to water, respectively (25°C). This two-fold higher concentration of H(2)S in the membrane translates into a rapid membrane permeability, P(m) = 3 cm s(-1). We used a mathematical model in three dimensions to gain insight into the diffusion of total sulfide in tissues. This model shows that the sphere of action of sulfide produced by a single cell expands to involve more than 200 neighboring cells, and that the resistance imposed by lipid membranes has a significant effect on the diffusional spread of sulfide at pH 7.4, increasing local concentrations. These results support the role of hydrogen sulfide as a paracrine signaling molecule and reveal advantageous pharmacokinetic properties for its therapeutic applications.

  8. Thermodynamics of Complex Sulfide Inclusion Formation in Ca-Treated Al-Killed Structural Steel

    Science.gov (United States)

    Guo, Yin-tao; He, Sheng-ping; Chen, Gu-jun; Wang, Qian

    2016-08-01

    Controlling the morphology of the sulfide inclusion is of vital importance in enhancing the properties of structural steel. Long strip-shaped sulfides in hot-rolled steel can spherize when, instead of the inclusion of pure single-phase MnS, the guest is a complex sulfide, such as an oxide-sulfide duplex and a solid-solution sulfide particle. In this study, the inclusions in a commercial rolled structural steel were investigated. Spherical and elongated oxide-sulfide duplex as well as single-phase (Mn,Ca)S solid solution inclusions were observed in the steel. A thermodynamic equilibrium between the oxide and sulfide inclusions was proposed to understand the oxide-sulfide duplex inclusion formation. Based on the equilibrium solidification principle, thermodynamic discussions on inclusion precipitation during the solidification process were performed for both general and resulfurized structural steel. The predicted results of the present study agreed well with the experimental ones.

  9. Hydrothermal Synthesis of Pure r-Phase Manganese(II) Sulfide without the Use of Organic Reagents

    Energy Technology Data Exchange (ETDEWEB)

    Michel, F.M.; Schoonen, M.A.A.; Zhang, X.V.; Martin, S.T.; Parise, J.B. (SBU); (Harvard)

    2008-06-18

    Recent studies exploring the role of metal sulfides as (photo)catalysts in prebiotic synthesis reactions provide the impetus for finding carbon-free synthesis methods for metal sulfides. The decomposition of organosulfur and organometallic precursor compounds is often the protocol for synthesizing bulk metal chalcogenides, such as manganese sulfide (MnS). Here we report a hydrothermal synthesis method for the formation of MnS in which a MnCl{sub 2} solution is injected into a preheated sulfide solution. By varying the temperature of injection and subsequent aging time, we can control the specific crystal phase of the product. Three MnS polymorphs are known, and two of these, {alpha}-MnS and {gamma}-MnS, form as pure phases in aqueous systems. The initial precipitate formed upon mixing of aqueous solutions of Mn{sup 2+} and S{sup 2-} at ambient temperature is nanocrystalline and is composed of a mixture of {gamma}-MnS (wurtzite structure) and {beta}-MnS (zinc blende structure). {beta}-MnS has not previously been identified as forming under aqueous conditions. The initial binary-phase precipitate can be transformed to pure, highly crystalline {gamma}-MnS by aging at temperatures as low as 150 C within 3 days. Aging to yield pure {alpha}-MnS requires temperatures in excess of 200 C for 3 days. Characterization of the products was performed using powder X-ray diffraction, total scattering and pair distribution function analysis, dynamic light scattering, and transmission and scanning electron microscopy. Chemical analyses were performed using colorimetric techniques.

  10. Investigation of chemical suppressants for inactivation of sulfide ores

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In order to investigate the effective control method of spontaneous combustion in the mining of sulfide ore deposits, This paper presents the testing results of several selected chemicals (water glass, calcium chloride, calcium oxide, magnesium oxide and their composites) as oxidation suppressants for sulfide ores. A weight increment scaling method was used to measure suppressant performance, and this method proved to be accurate, simple and convenient. Based on a large number of experiments, the test results show that four types of chemical mixtures demonstrate a good performance in reducing the oxidation rate of seven active sulfide ore samples by up to 27% to 100% during an initial 76 d period. The mixtures of water glass mixed with calcium chloride and magnesium oxide mixed with calcium chloride can also act as fire suppressants when used with fire sprinkling systems.

  11. Metal sulfide electrodes and energy storage devices thereof

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, Yet-Ming; Woodford, William Henry; Li, Zheng; Carter, W. Craig

    2017-02-28

    The present invention generally relates to energy storage devices, and to metal sulfide energy storage devices in particular. Some aspects of the invention relate to energy storage devices comprising at least one flowable electrode, wherein the flowable electrode comprises an electroactive metal sulfide material suspended and/or dissolved in a carrier fluid. In some embodiments, the flowable electrode further comprises a plurality of electronically conductive particles suspended and/or dissolved in the carrier fluid, wherein the electronically conductive particles form a percolating conductive network. An energy storage device comprising a flowable electrode comprising a metal sulfide electroactive material and a percolating conductive network may advantageously exhibit, upon reversible cycling, higher energy densities and specific capacities than conventional energy storage devices.

  12. Conspicuous veils formed by vibrioid bacteria on sulfidic marine sediment

    DEFF Research Database (Denmark)

    Thar, Roland Matthias; Kühl, Michael

    2002-01-01

    We describe the morphology and behavior of a hitherto unknown bacterial species that forms conspicuous veils (typical dimensions, 30 by 30 mm) on sulfidic marine sediment. The new bacteria were enriched on complex sulfidic medium within a benthic gradient chamber in oxygen-sulfide countergradients......, but the bacteria have so far not been isolated in pure culture, and a detailed characterization of their metabolism is still lacking. The bacteria are colorless, gram-negative, and vibrioid-shaped (1.3- to 2.5- by 4- to 10-µm) cells that multiply by binary division and contain several spherical inclusions of poly......, forming a cohesive whitish veil at the oxic-anoxic interface. Bacteria attached to the veil kept rotating and adapted their stalk lengths dynamically to changing oxygen concentrations. The joint action of rotating bacteria on the veil induced a homogeneous water flow from the oxic water region toward...

  13. Extraction of Nanosized Cobalt Sulfide from Spent Hydrocracking Catalyst

    Directory of Open Access Journals (Sweden)

    Samia A. Kosa

    2013-01-01

    Full Text Available The processes used for the extraction of metals (Co, Mo, and Al from spent hydrotreating catalysts were investigated in this study. A detailed mechanism of the metal extraction process is described. Additionally, a simulation study was performed to understand the sulfidizing mechanism. The suggested separation procedure was effective and achieved an extraction of approximately 80–90%. In addition, the sulfidization mechanism was identified. This sulfidizing process for Co was found to involve an intermediate, the structure of which was proposed. This proposed intermediate was confirmed through simulations. Moreover, the activities of the spent and the regenerated catalyst were examined in the cracking of toluene. The modification of the spent catalyst through the use of different iron oxide loadings improved the catalytic activity.

  14. Mechanism of sulfide effect on viscosity of HPAM polymer solution

    Institute of Scientific and Technical Information of China (English)

    康万利; 周阳; 王志伟; 孟令伟; 刘述忍; 白宝君

    2008-01-01

    The effect of sulfide on HPAM solution viscosity was studied using BROOKFIELD DV-II viscometer,and the interaction mechanism was discussed.The HPAM solution viscosity was investigated through fully reducing sulfide by the addition of hydrogen peroxide oxidation,and the mechanism of increasing polymer viscosity was investigated.The experimental results also show that there is a critical concentration of 15 mg/L.Below it,the loss rate of HPAM solution viscosity increases more rapidly,but becomes slowly above the critical concentration.A theoretical guidance for oilfields to prepare polymer solution using sewage-water by eliminating sulfide,and it is also importance to prepare polymer solution using sewage-water and save fresh water.

  15. On Magnesium Sulfide as the Carrier of the 30micron Emission Feature in Evolved Stars

    CERN Document Server

    Zhang, Ke; Li, Aigen

    2009-01-01

    A large number of carbon-rich evolved objects (asymptotic giant branch stars, protoplanetary nebulae, and planetary nebulae) in both the Milky Way galaxy and the Magellanic Clouds exhibit an enigmatic broad emission feature at 30 micron. This feature, extending from 24 micron to 45 micron, is very strong and accounts for up to 30% of the total infrared luminosity of the object. In literature it is tentatively attributed to magnesium sulfide (MgS) dust. Using the prototypical protoplanetary nebula around HD 56126 for illustrative purpose, however, in this work we show that in order for MgS to be responsible for the 30 micron feature, one would require an amount of MgS mass substantially exceeding what would be available in this source. We therefore argue that MgS is unlikely the carrier of the 30 micron feature seen in this source and in other sources as well.

  16. A Hypothesis: Hydrogen Sulfide Might Be Neuroprotective against Subarachnoid Hemorrhage Induced Brain Injury

    Directory of Open Access Journals (Sweden)

    Yong-Peng Yu

    2014-01-01

    Full Text Available Gases such as nitric oxide (NO and carbon monoxide (CO play important roles both in normal physiology and in disease. Recent studies have shown that hydrogen sulfide (H2S protects neurons against oxidative stress and ischemia-reperfusion injury and attenuates lipopolysaccharides (LPS induced neuroinflammation in microglia, exhibiting anti-inflammatory and antiapoptotic activities. The gas H2S is emerging as a novel regulator of important physiologic functions such as arterial diameter, blood flow, and leukocyte adhesion. It has been known that multiple factors, including oxidative stress, free radicals, and neuronal nitric oxide synthesis as well as abnormal inflammatory responses, are involved in the mechanism underlying the brain injury after subarachnoid hemorrhage (SAH. Based on the multiple physiologic functions of H2S, we speculate that it might be a promising, effective, and specific therapy for brain injury after SAH.

  17. The electronic transport characteristics of hybridized hexagon beryllium sulfide and graphene nanoribbons

    Science.gov (United States)

    Wang, Lihua; Ding, Bingjun; Guo, Yong

    2017-01-01

    Hybridized Z-BexSyCz (x + y + z = 16) systems connected by zigzag beryllium-sulfide (BeS) and graphene nanoribbons are theoretically designed, and their electronic transport characteristics are explored by first-principles approach. For the hybridized systems with unequal number of x and y, i.e. z is an odd number, an exceptional negative differential resistance (NDR) property occurs. However, for the hybridized systems including an even number of zigzag carbon chains, namely x equal to y, an interesting current-limited behavior happens. Meanwhile, the NDR phenomenon disappears. The spin transport properties of these hybridized Z-BexSyCz systems with parallel magnetism configuration also reveal the above odd-even dependence conductance behavior.

  18. Well-dispersed cadmium sulfide prepared in the presence of laponite by microwave irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zhaohui, Han; Lewis, S.W. [Curtin Univ. of Technology, Nanochemistry Research Institute, Dept. of Applied Chemistry, WA (Australia); Qing, Yang [University of Science and Technology of China, Dept. of Chemistry, Hefei (China); Jeffrey, Shic [Sydney Univ., Dept. of Chemical Engineering, NSW (Australia); Lud, C.Q. [Sydney Univ., Australian Key Centre for Microscopy and Microanalysis, NSW (Australia)

    2008-07-01

    The reactions of cadmium chloride and various sulfur sources in the suspension of laponite produced CdS nano-particles. Laponite was used to help keep good dispersion of the sulfide particles and it also facilitated the formation of the product by providing a basic environment when carbon disulfide was used as a source of sulfur in the reaction. The amount of laponite used in the preparation, heating rate and reaction temperature were tested for their effect on result. Different sulfur source materials were used for the preparation, and reactions involved in the preparation were discussed. The varied reaction conditions produced CdS particles with varied shape and size, and in good dispersion. (authors)

  19. Morphology and thermal studies of zinc sulfide and cadmium sulfide nanoparticles in polyvinyl alcohol matrix

    Energy Technology Data Exchange (ETDEWEB)

    Osuntokun, Jejenija; Ajibade, Peter A., E-mail: pajibade@ufh.ac.za

    2016-09-01

    Zn(II) and Cd(II) metal complexes of 1-cyano-1-carboethoxyethylene-2,2-dithiolato–κS,S’–bis (N,N-dimethylthiourea–κS) have been synthesized and characterized with analytical and spectroscopic techniques. The complexes were thermolysed in hexadecylamine at 200 °C to prepare ZnS and CdS nanoparticles. The nanoparticles were characterized with scanning electron microscope (SEM), transmission electron microscope (TEM), and powder X-ray diffraction (p-XRD). TEM images showed spherically shaped nanoparticles, whose sizes are in the range 4.33–7.21 nm for ZnS and 4.95–7.7 nm CdS respectively and XRD confirmed cubic crystalline phases for the nanoparticles. The optical band gap energy evaluated from the absorption spectra are 2.88 eV (430 nm) and 2.81 eV (440 nm) for the ZnS and CdS nanoparticles respectively. The as-prepared metal sulfide nanoparticles were further incorporated into polyvinyl alcohol (PVA) to give ZnS/PVA and CdS/PVA composites. The polymer nanocomposites were studied to investigate their morphology and thermal properties relative to the pure PVA. XRD diffractions indicated that the crystalline phases of the nanoparticles and the sizes in PVA matrices remained unaltered. Infra-red spectra studies revealed interactions between the PVA and the metal sulfide nanoparticles and TGA studies show that the ZnS/PVA and CdS/PVA nanocomposites exhibit better thermal stability than the pure PVA.

  20. Morphology and thermal studies of zinc sulfide and cadmium sulfide nanoparticles in polyvinyl alcohol matrix

    Science.gov (United States)

    Osuntokun, Jejenija; Ajibade, Peter A.

    2016-09-01

    Zn(II) and Cd(II) metal complexes of 1-cyano-1-carboethoxyethylene-2,2-dithiolato-κS,S'-bis(N,N-dimethylthiourea-κS) have been synthesized and characterized with analytical and spectroscopic techniques. The complexes were thermolysed in hexadecylamine at 200 °C to prepare ZnS and CdS nanoparticles. The nanoparticles were characterized with scanning electron microscope (SEM), transmission electron microscope (TEM), and powder X-ray diffraction (p-XRD). TEM images showed spherically shaped nanoparticles, whose sizes are in the range 4.33-7.21 nm for ZnS and 4.95-7.7 nm CdS respectively and XRD confirmed cubic crystalline phases for the nanoparticles. The optical band gap energy evaluated from the absorption spectra are 2.88 eV (430 nm) and 2.81 eV (440 nm) for the ZnS and CdS nanoparticles respectively. The as-prepared metal sulfide nanoparticles were further incorporated into polyvinyl alcohol (PVA) to give ZnS/PVA and CdS/PVA composites. The polymer nanocomposites were studied to investigate their morphology and thermal properties relative to the pure PVA. XRD diffractions indicated that the crystalline phases of the nanoparticles and the sizes in PVA matrices remained unaltered. Infra-red spectra studies revealed interactions between the PVA and the metal sulfide nanoparticles and TGA studies show that the ZnS/PVA and CdS/PVA nanocomposites exhibit better thermal stability than the pure PVA.

  1. Migration and enrichment of trace elements of Lower Palaeozoic carbonate rock strata in Beijing

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Analyses of trace elements of the Lower Palaeozoic carbonate rock strata in Beijing show that the contents of As, Hg, F increase from primary carbonate rocks to weathered carbonate rocks and from primary carbonate rocks to the soil coexisting with carbonate rocks, but the distribution regularity of S is not obvious. In the whole weathered stages, the sorption of As is mainly affected by Fe2O3. In soil Fe2O3 is also the main affecting factor of Hg enrichment. The main existing forms of Hg in primary carbonate rocks should simply be physical adsorption, coprecipitation and false isomorphous form between surface of carbonate rock and Hg. In soil the enrichment of F has little relationship with sul-fides and Fe2O3. In primary carbonate rocks, F is mainly absorbed by sulfides and clay minerals, etc. Weathered samples have closer genetic relationships with primary carbonate rocks. This also implies that weathered carbonate rocks have the close existing forms to that of primary carbonate rocks. In primary carbonate rocks FeS2 and FeS are the main forms of S, and sulfides have fixation effect on some heavy metals, whereas in weathered carbonate rocks and soil the fixation effect is weakened.

  2. Carbonyl Sulfides as Possible Intermediates in the Photolysis of Oxathiiranes

    DEFF Research Database (Denmark)

    Carlsen, Lars; Snyder, J. P.; Holm, A.

    1981-01-01

    of sulfine to ketone via the oxathiirane and the subsequent blue intermediate implies the absence of triplet and biradical singlet transients. The unknown carbonyl sulfide functionality, R2C&z.dbnd;O&z.dbnd;S, thereby emerges as a strong candidate for producing the visible absorption. Comparison of the wave...... functions for CH2&z.dbnd;S&z.dbnd;O and CH2&z.dbnd;O&z.dbnd;S arising from MNDO limited CI geometry optimizations leads to the conclusion that the carbonyl sulfide structure is best described as a zwitterion rather than as a singlet biradical. The failure to observe cycloaddition products between the blue...

  3. High conducting oxide--sulfide composite lithium superionic conductor

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Chengdu; Rangasamy, Ezhiylmurugan; Dudney, Nancy J.; Keum, Jong Kahk; Rondinone, Adam Justin

    2017-01-17

    A solid electrolyte for a lithium-sulfur battery includes particles of a lithium ion conducting oxide composition embedded within a lithium ion conducting sulfide composition. The lithium ion conducting oxide composition can be Li.sub.7La.sub.3Zr.sub.2O.sub.12 (LLZO). The lithium ion conducting sulfide composition can be .beta.-Li.sub.3PS.sub.4 (LPS). A lithium ion battery and a method of making a solid electrolyte for a lithium ion battery are also disclosed.

  4. Experimental constraints on gold and silver solubility in iron sulfides

    Energy Technology Data Exchange (ETDEWEB)

    Pal' yanova, Galina [Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, 3, Koptyuga, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, Russia, 2, Pirogova, Novosibirsk, 630090 (Russian Federation); Mikhlin, Yuri [Institute of Chemistry and Chemical Technology, Siberian Branch of the Russian Academy of Sciences, Akademgorodok, 50/24, Krasnoyarsk, 660036 (Russian Federation); Kokh, Konstantin, E-mail: k.a.kokh@gmail.com [Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, 3, Koptyuga, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, Russia, 2, Pirogova, Novosibirsk, 630090 (Russian Federation); Siberian Physical–Technical Institute of Tomsk State University, 1, Novosobornaya, Tomsk, 634050 (Russian Federation); Karmanov, Nick [Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, 3, Koptyuga, Novosibirsk, 630090 (Russian Federation); Seryotkin, Yurii [Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, 3, Koptyuga, Novosibirsk, 630090 (Russian Federation); Novosibirsk State University, Russia, 2, Pirogova, Novosibirsk, 630090 (Russian Federation)

    2015-11-15

    Experiments were performed to determine crystallization of Fe,S-melts (pyriti≿ and troilitic with molar ratio S/Fe ratios of 2 and 1, respectively) containing traces of gold and silver at (Ag/Au){sub wt} ratios varying from 10 to 0.1. The solid products were studied by optical microscopy, scanning electron microscopy, X-ray powder diffraction (XRD), microprobe analysis, and X-ray photoelectron spectroscopy (XPS) in order to reveal the concentration limits of “invisible” gold and silver in magmatic iron sulfides, and to determine the influence of sulfur on forms of precious metals in the Fe–S system with different Ag/Au ratios. Au–Ag phases do not form inclusions but instead concentrate on the grain boundaries in the synthetic pyrrhotite and troilite, while pyrite comprises micro- (1–5 μm) and macroinclusions of Au–Ag alloys and Au–Ag sulfides. In “pyriti≿” systems, the fineness of alloys increases from 650 to 970‰ and the composition of sulfides changes from acanthite (Ag{sub 2}S) to uytenbogaardtite (Ag{sub 3}AuS{sub 2}) and petrovskaite (AgAuS) as the Ag/Au ratio decreases. The concentrations of “invisible” precious metals revealed in troilite were 0.040 ± 0.013 wt.% Au and 0.079 ± 0.016 wt.% Ag. Measured concentrations in pyrite and pyrrhotite were <0.024 wt.% Au and <0.030 wt.% Ag. The surface layers of iron sulfides probed with XPS were enriched in the precious metals, and in silver relative to gold, especially in the systems with Fe/S = 1, probably, due to depletion of the metallic alloy surfaces with gold. Au- and Ag-bearing iron sulfides crystallized primarily from melts may be the source of redeposited phases in hydrothermal and hypergene processes. - Highlights: • The samples of Fe–S–Au–Ag system were synthesized. • Coupled solubility of gold and silver in iron sulfides was specified. • Ag–Au inclusions on surfaces of iron sulfides are likely to be enriched in silver. • Au–Ag sulfides can exist along with

  5. The Sulfide Capacity of Iron Oxide-Rich Slags

    Science.gov (United States)

    Motlagh, M.

    1988-03-01

    The relationship between the sulfide capacity of slags rich in iron oxide and the sulfur partition ratio between the metal and slag is strongly related to the slag's iron oxide concentration. For slags containing little or no lime, this relationship is linear for a constant concentration of iron oxide in the slag. The effect of silica on changes in the sulfide capacity of slags rich in iron oxide is similar to that of basic steel-making slags, particularly at low activity of silica in slag.

  6. Strong soil source of carbonyl sulfide in an agricultural field

    Science.gov (United States)

    Maseyk, K. S.; Seibt, U.; Berry, J. A.; Billesbach, D. P.; Campbell, J.; Torn, M. S.

    2012-12-01

    A promising new approach to constrain biosphere-atmosphere carbon and water exchange is the use of carbonyl sulfide (COS). COS is taken up by leaves via the same pathway as CO2, leading to a close coupling of vegetation COS and CO2 fluxes during photosynthesis. Therefore it has been proposed that the gross fluxes of photosynthesis and respiration can be quantified through the concurrent measurements of COS and CO2. A necessary requirement for this approach at ecosystem and continental scales are estimates of soil COS fluxes. Soil is largely considered a sink for COS, but our knowledge of in situ soil COS fluxes remains very limited. We measured soil COS fluxes in a wheat field in Oklahoma from April to June 2012, using a novel combination of an automated soil chamber coupled to a COS laser analyzer. We provide the first continuous record of soil COS fluxes under natural conditions, and report on a phenomenon that has not been observed before. In contrast to the majority of published results, we found that the agricultural soil was a strong source of COS under most conditions during the campaign. The COS flux over the study period was highly correlated with soil temperature. Up to a soil temperature of around 15°C, the soil acted as a COS sink. Above 15°C, it acted a source of COS, with fluxes of up to 25 pmol m-2 s-1. To locate the source of the COS production, we investigated different soil components. Wheat roots were found to be emitting COS under all conditions. Root-free soil was a COS sink up to a soil temperature of around 25°C, but turned into a COS source at higher soil temperatures. We also observed COS production from the roots of several other species, indicating that this may be a widespread phenomenon. Using eddy covariance data of COS and CO2 that was collected concurrently with the soil measurements, we also demonstrate how the soil COS source can be taken into account when partitioning net ecosystem exchange into photosynthesis and respiration.

  7. Thermochemical hydrogen production via a cycle using barium and sulfur - Reaction between barium sulfide and water

    Science.gov (United States)

    Ota, K.; Conger, W. L.

    1977-01-01

    The reaction between barium sulfide and water, a reaction found in several sulfur based thermochemical cycles, was investigated kinetically at 653-866 C. Gaseous products were hydrogen and hydrogen sulfide. The rate determining step for hydrogen formation was a surface reaction between barium sulfide and water. An expression was derived for the rate of hydrogen formation.

  8. The Sulfidation of gamma-Alumina and Titania Supported (Cobalt) Molybdenum Oxide Catalysts Monitored by EXAFS.

    NARCIS (Netherlands)

    Koningsberger, D.C.; Leliveld, R.G.; Dillen, A.J. van; Geus, John W.

    1997-01-01

    The sulfidation of @c-alumina- and titania-supported(cobalt)molybdenum oxide catalysts has been studied with X-rayabsorption spectroscopy and temperature programmed sulfidation (TPS).The catalysts were stepwise sulfided at temperatures between 298 and673 K and their structure was determined with EXA

  9. Selective precipitation of heavy metals as controlled by a sulfide-selective electrode

    NARCIS (Netherlands)

    Veeken, A.H.M.; Vries, S.; Mark, van der A.

    2003-01-01

    Sulfide precipitation is superior to hydroxide precipitation for removal of heavy metals from wastewaters as it results in lower effluent concentrations and less interference from chelating agents. However, sulfide precipitation is not widely applied in practice because the dosing of sulfide cannot

  10. 76 FR 69136 - Hydrogen Sulfide; Community Right-to-Know Toxic Chemical Release Reporting

    Science.gov (United States)

    2011-11-08

    ... AGENCY 40 CFR Part 372 RIN 2025-AA27 Hydrogen Sulfide; Community Right-to-Know Toxic Chemical Release... hydrogen sulfide and methyl mercaptan found at 40 CFR 372.65. The document published in the Federal... requirements for only hydrogen sulfide. The Office of the Federal Register mistakenly lifted the stay of...

  11. Sulfide-iron interactions in domestic wastewater from a gravity sewer

    NARCIS (Netherlands)

    Nielsen, A.H.; Lens, P.N.L.; Vollertsen, J.; Hvitved-Jacobsen, Th.

    2005-01-01

    Interactions between iron and sulfide in domestic wastewater from a gravity sewer were investigated with particular emphasis on redox cycling of iron and iron sulfide formation. The concentration ranges of iron and total sulfide in the experiments were 0.4-5.4 mg Fe L-1 and 0-5.1 mg S L-1, respectiv

  12. SULFIDE OXIDATION UNDER OXYGEN LIMITATION BY A THIOBACILLUS-THIOPARUS ISOLATED FROM A MARINE MICROBIAL MAT

    NARCIS (Netherlands)

    VANDENENDE, FP; VANGEMERDEN, H

    1993-01-01

    The colorless sulfur bacterium Thiobacillus thioparus T5, isolated from a marine microbial mat, was grown in continuous culture under conditions ranging from sulfide limitation to oxygen limitation. Under sulfide-limiting conditions, sulfide was virtually completely oxidized to sulfate. Under oxygen

  13. Identifying the Prospective Area of Sulfide Groundwater within the Area of Palvantash Oil and Gas Deposit

    Directory of Open Access Journals (Sweden)

    M. R. Zhurayev

    2014-03-01

    Full Text Available This paper describes the methodology of prospecting for sulfide groundwater in the area of Palvantash oil fields. In result of study allowed determining the favorable conditions for the sulfide waters formation, and mapping the areas of different sulfide water concentration. The relatively permeable areas were established and the water borehole positions were recommended.

  14. The sulfur partition ratio with Fe-CSAT melts and the sulfide capacity of CaO-SiO2-Na2O- (Ai2O3) slags

    Science.gov (United States)

    Chan, A. H.; Fruehan, R. J.

    1989-02-01

    The sulfur partition ratio between slag and carbon saturated iron and the sulfide capacity of CaO-Na2O-SiO2 slags and a 48 pet CaO-45 pet Al2O3-7 pet SiO2-(Na2O) slag have been mea-sured at 1400 °C. The addition of Na2O to a CaO-SiO2 slag increases the sulfur partition ratio and the sulfide capacity; however, Na2O at low concentrations has no measurable effect on the sulfide capacity of a CaO-Al2O3-SiO2 slag. To convert the sulfur partition ratio to the sulfide capacity, the oxygen potential was calculated assuming equilibrium between iron in the alloy and FeO in the slag with the activity of FeO calculated via a regular solution model. The optical basicity may be used to correlate the data, but at high Na2O contents the data do not adhere to the correlation previously developed for CaO-based slags.

  15. S/Se In Sulfide Inclusion In Diamond

    Science.gov (United States)

    Thomassot, E.; Couffignal, F.; Lorand, J.; Bureau, H.; Cartigny, P.; Harris, J. W.

    2009-05-01

    Sulfides are among the most common minerals found as inclusions in diamonds. Being protected from any alteration after diamond formation, they likely represent the most pristine sulfide sample of mantle rocks. Their chemical composition in major and minor elements (mainly Ni, Cu and Cr), as determined using Electron Probe Micro Analyse (EPMA), is commonly used to determine the rock type in which the diamond formed. Here we propose to apply the same technique to the trace element abundance determination. We performed selenium (Se) on sulfide inclusion in diamonds. The S/Se value could help understanding whether the diamond formed in an eclogitic or peridotitic environment and may also constrain on the magmatic differentiation of diamonds host rock as well as provide a potential surface (hydrothermal) signature in diamond inclusions. A trace element measurement scheme has been developed by EPMA at the CAMPARIS centre (Paris). Se-abundance was obtained using a 30 kV accelerating voltage and 100nA probe current. Total counting time was 800s for peak (1.1 Å ) and 400s for background on both side of peak. Analyses were duplicated by μPIXE using the LPS nuclear microprobe facility (SIS2M CEA Saclay, France). Maps from 30x30 μm2 to 70x70 μm2 were obtained by scanning a 4x4 μm2 proton beam of 3MeV, 600 pA, (0.4 to 2 μC). The two techniques show good agreement and we conclude that EPMA is well suited for accurate and precise Se measurements. We analysed five samples; two monosulfide solid solution (MSS) (Ni>22wt%) typical of the peridotitic paragenesis (P-type), and three Ni-poor sulfides (Ni<7wt%) typical of the eclogitic paragenesis (E-type). In P-type sulfides, Se-content (260 ppm) is significantly higher than previously reported in sulfides from mantle-derived lherzolites (40-160 ppm), pyroxenites (25-45 ppm) or harzburgite. The value of S/Se in MSS is low (˜1400) compared to those of the primitive mantle reservoir (3,300; McDounough et al., 1995 Chemical Geology

  16. Decomposition of dimethyl sulfide in a wire-cylinder pulse corona reactor

    Institute of Scientific and Technical Information of China (English)

    Jian-tao YANG; Yao SHI; Jie CHEN; Qing-fa SU; Da-hui WANG; Jing CAO

    2009-01-01

    Decomposition of dimethyl sulfide (DMS) in air was investigated experimentally by using a wire-cylinder dielectric barrier discharge (DBD) reactor at room temperature and atmospheric pressure. A new type of high pulse voltage source with a thyratron switch and a Blumlein pulse-forming network (BPFN) was adopted in our experiments. The maximum power output of the pulse voltage source and the maximum peak voltage were 1 kW and 100 kV, respectively. The important parameters affecting odor decomposition, including peak voltage, pulse frequency, gas flow rate, initial concentration, and humidity, which influenced the removal efficiency, were investigated. The results showed that DMS could be treated effectively and almost a 100% removal efficiency was achieved at the conditions with an initial concentration of 832 mg/m3 and a gas flow rate of 1000 ml/min. Humidity boosts the removal efficiency and improves the energy yield (EY) greatly. The EY of 832 mg/m3 DMS was 2.87 mg/kJ when the relative humidity was above 30%. In the case of DMS removal, the ozone and nitrogen oxides were observed in the exhaust gas. The carbon and sulfur elements of DMS were mainly converted to carbon dioxide, carbon monoxide and sulfur dioxide. Moreover, sulfur was discovered in the reactor. According to the results, the optimization design for the reactor and the matching of high pulse voltage source can be reckoned.

  17. A coumarin-based colorimetric fluorescent probe for hydrogen sulfide

    Indian Academy of Sciences (India)

    Yanqiu Yang; Yu Liu; Liang Yang; Jun Liu; Kun Li; Shunzhong Luo

    2015-03-01

    A coumarin-based fluorescent probe for selective detection of hydrogen sulfide (H2S) is presented. This `off–on’ probe exhibited high selectivity towards H2S in aqueous solution with a detection limit of 30 nM. Notably, because of its dual nucleophilicity, the probe could avoid the interference of thiols and other sulfur containing compounds.

  18. Sulfide Formation And Its Impacts On A Developing Country

    DEFF Research Database (Denmark)

    Matias, Natércia; Mutuvúie, Raúl; Vollertsen, Jes;

    2014-01-01

    is expected in the near future, with the associated longer wastewater travel times and increasing problems of septicity and hydrogen sulfide gas impacts. In order to better understand the in-sewer processes under local conditions, evaluate risks and exemplify how to support general drainage systems planning...

  19. Hydrogen sulfide : role in vascular physiology and pathology

    NARCIS (Netherlands)

    Holwerda, Kim M.; Karumanchi, S. Ananth; Lely, A. Titia

    2015-01-01

    Purpose of reviewHydrogen sulfide (H2S), a colorless gas that is endogenously generated in mammals from cysteine, has important biological functions. Within the vasculature it regulates vessel tone and outgrowth of new vessels. This review summarizes recent literature on H2S signaling in the vascula

  20. Bio-reduction of sulfide minerals to recover invisible gold

    NARCIS (Netherlands)

    Hol, A.

    2011-01-01

      Sulfide minerals, like pyrite and arsenopyrite, are of economical interest due to the presence of invisible gold locked inside these minerals. As fine grinding is often not sufficient to liberate the gold from these minerals, additional destruction techniques, based on chemical and biologica

  1. Potential Applications of Hydrogen Sulfide-Induced Suspended Animation

    NARCIS (Netherlands)

    H. Aslami; M.J. Schultz; N.P. Juffermans

    2009-01-01

    A suspended animation-like state has been induced in rodents with the use of hydrogen sulfide, resulting in hypothermia with a concomitant reduction in metabolic rate. Also oxygen demand was reduced, thereby protecting against hypoxia. Several therapeutic applications of induction of a hibernation-l

  2. Micelle Mediated Trace Level Sulfide Quantification through Cloud Point Extraction

    Directory of Open Access Journals (Sweden)

    Samrat Devaramani

    2012-01-01

    Full Text Available A simple cloud point extraction protocol has been proposed for the quantification of sulfide at trace level. The method is based on the reduction of iron (III to iron (II by the sulfide and the subsequent complexation of metal ion with nitroso-R salt in alkaline medium. The resulting green-colored complex was extracted through cloud point formation using cationic surfactant, that is, cetylpyridinium chloride, and the obtained surfactant phase was homogenized by ethanol before its absorbance measurement at 710 nm. The reaction variables like metal ion, ligand, surfactant concentration, and medium pH on the cloud point extraction of the metal-ligand complex have been optimized. The interference effect of the common anions and cations was studied. The proposed method has been successfully applied to quantify the trace level sulfide in the leachate samples of the landfill and water samples from bore wells and ponds. The validity of the proposed method has been studied by spiking the samples with known quantities of sulfide as well as comparing with the results obtained by the standard method.

  3. Luminescence in Sulfides: A Rich History and a Bright Future

    Directory of Open Access Journals (Sweden)

    Philippe F. Smet

    2010-04-01

    Full Text Available Sulfide-based luminescent materials have attracted a lot of attention for a wide range of photo-, cathodo- and electroluminescent applications. Upon doping with Ce3+ and Eu2+, the luminescence can be varied over the entire visible region by appropriately choosing the composition of the sulfide host. Main application areas are flat panel displays based on thin film electroluminescence, field emission displays and ZnS-based powder electroluminescence for backlights. For these applications, special attention is given to BaAl2S4:Eu, ZnS:Mn and ZnS:Cu. Recently, sulfide materials have regained interest due to their ability (in contrast to oxide materials to provide a broad band, Eu2+-based red emission for use as a color conversion material in white-light emitting diodes (LEDs. The potential application of rare-earth doped binary alkaline-earth sulfides, like CaS and SrS, thiogallates, thioaluminates and thiosilicates as conversion phosphors is discussed. Finally, this review concludes with the size-dependent luminescence in intrinsic colloidal quantum dots like PbS and CdS, and with the luminescence in doped nanoparticles.

  4. Magmatic sulfides in the porphyritic chondrules of EH enstatite chondrites

    CERN Document Server

    Piani, Laurette; Libourel, Guy; Tissandier, Laurent

    2016-01-01

    The nature and distribution of sulfides within 17 porphyritic chondrules of the Sahara 97096 EH3 enstatite chondrite have been studied by backscattered electron microscopy and electron microprobe in order to investigate the role of gas-melt interactions in the chondrule sulfide formation. Troilite (FeS) is systematically present and is the most abundant sulfide within the EH3 chondrite chondrules. It is found either poikilitically enclosed in low-Ca pyroxenes or scattered within the glassy mesostasis. Oldhamite (CaS) and niningerite [(Mg,Fe,Mn)S] are present in about 60% of the chondrules studied. While oldhamite is preferentially present in the mesostasis, niningerite associated with silica is generally observed in contact with troilite and low-Ca pyroxene. The chondrule mesostases contain high abundances of alkali and volatile elements as well as silica. Our data suggest that most of the sulfides found in EH3 chondrite chondrules are magmatic minerals that formed after the dissolution of S from a volatile-r...

  5. 21 CFR 872.1870 - Sulfide detection device.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Sulfide detection device. 872.1870 Section 872.1870 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... periodontal pocket probing depths, detect the presence or absence of bleeding on probing, and detect...

  6. Hydrogen sulfide release from dairy manure storages containing gypsum bedding

    Science.gov (United States)

    Recycled gypsum products can provide a cost-effective bedding alternative for dairy producers. Manufacturers report reduced odors, moisture and bacteria in the stall environment when compared to traditional bedding. Gypsum provides a sulfate source that can be converted to hydrogen sulfide under ana...

  7. Electrogenerative leaching of nickel sulfide concentrate with ferric chloride

    Institute of Scientific and Technical Information of China (English)

    王少芬; 方正; 王云燕; 陈阳国

    2004-01-01

    In order to utilize the chemical energy in hydrometallurgical process of sulfide minerals reasonably and to simplify the purifying process, the electrogenerative process was applied and a dual cell system was introduced to investigate FeCl3 leaching of nickel sulfide concentrate. Some factors influencing the electrogenerative leaching, such as electrode structure, temperature and solution concentration were studied. The results show that a certain quantity of electrical energy accompanied with the leached products can be acquired in the electrogenerative leaching process.The output current and power increase with the addition of acetylene black to the electrode. Varying the components of electrode just affects the polarization degree of anode. Increasing FeCl3 concentration results in a sharp increase in the output of the leaching cell when c(FeCl3) is less than 0.1 mol/L. The optimum value of NaCl concentration for electrogenerative leaching nickel sulfide concentrate with FeCl3 is 3.0 mol/L. Temperature influences electrogenerative leaching by affecting anodic and cathodic polarization simultaneously. The apparent activation energy is determined to be 34.63 kJ/mol in the range of 298 K to 322 K. The leaching rate of Ni2+ is 29.3% after FeCl3 electrogenerative leaching of nickel sulfide concentrate for 620 min with a filter bag electrode.

  8. Synthesis and photovoltaic application of coper (I) sulfide nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yue; Wadia, Cyrus; Ma, Wanli; Sadtler, Bryce; Alivisatos, A.Paul

    2008-06-24

    We present the rational synthesis of colloidal copper(I) sulfide nanocrystals and demonstrate their application as an active light absorbing component in combination with CdS nanorods to make a solution-processed solar cell with 1.6percent power conversion efficiency on both conventional glass substrates and flexible plastic substrates with stability over a 4 month testing period.

  9. Adsorption of hydrogen sulfide on montmorillonites modified with iron.

    Science.gov (United States)

    Nguyen-Thanh, Danh; Block, Karin; Bandosz, Teresa J

    2005-04-01

    Sodium-rich montmorillonite was modified with iron in order to introduce active centers for hydrogen sulfide adsorption. In the first modification, interlayer sodium cations were exchanged with iron. In another modification, iron oxocations were introduced to the clay surface. The most elaborated modification was based on doping of iron within the interlayer space of aluminum-pillared clay. The modified clay samples were tested as hydrogen sulfide adsorbents. Iron-doped samples showed a significant improvement in the capacity for H2S removal, despite of a noticeable decrease in microporosity compared to the initial pillared clay. The smallest capacity was obtained for the clay modified with iron oxocations. Variations in adsorption capacity are likely due to differences in the chemistry of iron species, degree of their dispersion on the surface, and accessibility of small pores for H2S molecule. The results suggest that on the surface of iron-modified clay hydrogen sulfide reacts with Fe(+3) forming sulfides or it is catalytically oxidized to SO2 on iron (hydro)oxides. Subsequent oxidation may lead to sulfate formation.

  10. Estimation of bacterial hydrogen sulfide production in vitro

    Directory of Open Access Journals (Sweden)

    Amina Basic

    2015-06-01

    Full Text Available Oral bacterial hydrogen sulfide (H2S production was estimated comparing two different colorimetric methods in microtiter plate format. High H2S production was seen for Fusobacterium spp., Treponema denticola, and Prevotella tannerae, associated with periodontal disease. The production differed between the methods indicating that H2S production may follow different pathways.

  11. Improvements in the manufacture of sulfur from hydrogen sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Azoulay, A.

    1968-12-23

    In this process for the manufacture of sulfur from hydrogen sulfide and sulfur dioxide, the sulfur is separated from the gas after reaction by direct contact by cooling with a cooling liquid. The sulfur is carried away by the cooling liquid.

  12. Lanthanide complexes as luminogenic probes to measure sulfide levels in industrial samples.

    Science.gov (United States)

    Thorson, Megan K; Ung, Phuc; Leaver, Franklin M; Corbin, Teresa S; Tuck, Kellie L; Graham, Bim; Barrios, Amy M

    2015-10-08

    A series of lanthanide-based, azide-appended complexes were investigated as hydrogen sulfide-sensitive probes. Europium complex 1 and Tb complex 3 both displayed a sulfide-dependent increase in luminescence, while Tb complex 2 displayed a decrease in luminescence upon exposure to NaHS. The utility of the complexes for monitoring sulfide levels in industrial oil and water samples was investigated. Complex 3 provided a sensitive measure of sulfide levels in petrochemical water samples (detection limit ∼ 250 nM), while complex 1 was capable of monitoring μM levels of sulfide in partially refined crude oil.

  13. Thermochemical hydrogen production via a cycle using barium and sulfur: reaction between barium sulfide and water

    Energy Technology Data Exchange (ETDEWEB)

    Ota, K.; Conger, W.L.

    1977-01-01

    The reaction between barium sulfide and water, a reaction found in several sulfur based thermochemical cycles, was investigated kinetically at 653 to 866/sup 0/C. Gaseous products were hydrogen and hydrogen sulfide. The rate determining step for hydrogen formation was a surface reaction between barium sulfide and water. The rate of formation of hydrogen can be expressed as: RH2 = 1.07 x 10/sup -2/ exp (-3180/RT) (mol H/sub 2//mol BaS s). Hydrogen sulfide was produced during the initial period of reaction and the quantity of hydrogen sulfide formed during this period decreased as the temperature of reaction was increased.

  14. Volcanogenic massive sulfide occurrence model: Chapter C in Mineral deposit models for resource assessment

    Science.gov (United States)

    Shanks, W.C. Pat; Koski, Randolph A.; Mosier, Dan L.; Schulz, Klaus J.; Morgan, Lisa A.; Slack, John F.; Ridley, W. Ian; Dusel-Bacon, Cynthia; Seal, Robert R., II; Piatak, Nadine M.; Shanks, W.C. Pat; Thurston, Roland

    2012-01-01

    Volcanogenic massive sulfide deposits, also known as volcanic-hosted massive sulfide, volcanic-associated massive sulfide, or seafloor massive sulfide deposits, are important sources of copper, zinc, lead, gold, and silver (Cu, Zn, Pb, Au, and Ag). These deposits form at or near the seafloor where circulating hydrothermal fluids driven by magmatic heat are quenched through mixing with bottom waters or porewaters in near-seafloor lithologies. Massive sulfide lenses vary widely in shape and size and may be podlike or sheetlike. They are generally stratiform and may occur as multiple lenses.

  15. Formation of nanocolloidal metacinnabar in mercury-DOM-sulfide systems

    Science.gov (United States)

    Gerbig, Chase A.; Kim, Christopher S.; Stegemeier, John P.; Ryan, Joseph N.; Aiken, George R.

    2011-01-01

    Direct determination of mercury (Hg) speciation in sulfide-containing environments is confounded by low mercury concentrations and poor analytical sensitivity. Here we report the results of experiments designed to assess mercury speciation at environmentally relevant ratios of mercury to dissolved organic matter (DOM) (i.e., -1) by combining solid phase extraction using C18 resin with extended X-ray absorption fine structure (EXAFS) spectroscopy. Aqueous Hg(II) and a DOM isolate were equilibrated in the presence and absence of 100 μM total sulfide. In the absence of sulfide, mercury adsorption to the resin increased as the Hg:DOM ratio decreased and as the strength of Hg-DOM binding increased. EXAFS analysis indicated that in the absence of sulfide, mercury bonds with an average of 2.4 ± 0.2 sulfur atoms with a bond length typical of mercury-organic thiol ligands (2.35 Å). In the presence of sulfide, mercury showed greater affinity for the C18 resin, and its chromatographic behavior was independent of Hg:DOM ratio. EXAFS analysis showed mercury–sulfur bonds with a longer interatomic distance (2.51–2.53 Å) similar to the mercury–sulfur bond distance in metacinnabar (2.53 Å) regardless of the Hg:DOM ratio. For all samples containing sulfide, the sulfur coordination number was below the ideal four-coordinate structure of metacinnabar. At a low Hg:DOM ratio where strong binding DOM sites may control mercury speciation (1.9 nmol mg-1) mercury was coordinated by 2.3 ± 0.2 sulfur atoms, and the coordination number rose with increasing Hg:DOM ratio. The less-than-ideal coordination numbers indicate metacinnabar-like species on the nanometer scale, and the positive correlation between Hg:DOM ratio and sulfur coordination number suggests progressively increasing particle size or crystalline order with increasing abundance of mercury with respect to DOM. In DOM-containing sulfidic systems nanocolloidal metacinnabar-like species may form, and these species need to

  16. Magmatic sulfides in the porphyritic chondrules of EH enstatite chondrites

    Science.gov (United States)

    Piani, Laurette; Marrocchi, Yves; Libourel, Guy; Tissandier, Laurent

    2016-12-01

    The nature and distribution of sulfides within 17 porphyritic chondrules of the Sahara 97096 EH3 enstatite chondrite have been studied by backscattered electron microscopy and electron microprobe in order to investigate the role of gas-melt interactions in the chondrule sulfide formation. Troilite (FeS) is systematically present and is the most abundant sulfide within the EH3 chondrite chondrules. It is found either poikilitically enclosed in low-Ca pyroxenes or scattered within the glassy mesostasis. Oldhamite (CaS) and niningerite [(Mg,Fe,Mn)S] are present in ≈60% of the chondrules studied. While oldhamite is preferentially present in the mesostasis, niningerite associated with silica is generally observed in contact with troilite and low-Ca pyroxene. The Sahara 97096 chondrule mesostases contain high abundances of alkali and volatile elements (average Na2O = 8.7 wt.%, K2O = 0.8 wt.%, Cl = 7100 ppm and S = 3700 ppm) as well as silica (average SiO2 = 62.8 wt.%). Our data suggest that most of the sulfides found in EH3 chondrite chondrules are magmatic minerals that formed after the dissolution of S from a volatile-rich gaseous environment into the molten chondrules. Troilite formation occurred via sulfur solubility within Fe-poor chondrule melts followed by sulfide saturation, which causes an immiscible iron sulfide liquid to separate from the silicate melt. The FeS saturation started at the same time as or prior to the crystallization of low-Ca pyroxene during the high temperature chondrule forming event(s). Protracted gas-melt interactions under high partial pressures of S and SiO led to the formation of niningerite-silica associations via destabilization of the previously formed FeS and low-Ca pyroxene. We also propose that formation of the oldhamite occurred via the sulfide saturation of Fe-poor chondrule melts at moderate S concentration due to the high degree of polymerization and the high Na-content of the chondrule melts, which allowed the activity of Ca

  17. Direct rapid determination of traces of sulfide in environment samples

    Institute of Scientific and Technical Information of China (English)

    郭方遒; 黄兰芳; 梁逸曾

    2002-01-01

    An improved ethylene blue method for determination of sulfide is developed. It has been adapted to a direct determination of sulfide by both common spectrophotometric method and total differential spectrophotometric method. In common spectrophotometric method, the calibration curve is A=1.69ρ+0.006 and the correlation coefficient is 0.9994.The apparent molar absorptivity is 5.42×104 L*mol-1*cm-1 and calibration curve is liner when ρ is in the range of 0-0.9 mg*L-1. In total differential spectrophotometric method, the calibration curve is A=9.25ρ+0.004 and the correlation coefficient is 0.9996. The apparent molar absorptivity is 2.96×105 L*mol-1*cm-1and calibration curve is liner when ρ is in the range of 0-0.10 mg*L-1. The sensitivity of this method is increased significantly compared with the former ethylene blue method. The speed of reaction is also faster than the former one. The limit of detection is found to be 1.0 ng*mL-1 by both common spectrophotometric method and total differential spectrophotometric method. Ten replicate analyses of a sample solution containing 100 ng*mL-1sulfide give a relative standard deviation of 1.8%. The effects of various cations and anions on the determination of sulfide are studied and procedures for removal of interference is described. The method is used for the determination of sulfide in environment samples with satisfactory results.

  18. Biogeographic Congruency among Bacterial Communities from Terrestrial Sulfidic Springs

    Directory of Open Access Journals (Sweden)

    Brendan eHeadd

    2014-09-01

    Full Text Available Terrestrial sulfidic springs support diverse microbial communities by serving as stable conduits for geochemically diverse and nutrient-rich subsurface waters. Microorganisms that colonize terrestrial springs likely originate from groundwater, but may also be sourced from the surface. As such, the biogeographic distribution of microbial communities inhabiting sulfidic springs should be controlled by a combination of spring geochemistry and surface and subsurface transport mechanisms, and not necessarily geographic proximity to other springs. We examined the bacterial diversity of seven springs to test the hypothesis that occurrence of taxonomically similar microbes, important to the sulfur cycle, at each spring is controlled by geochemistry. Complementary Sanger sequencing and 454 pyrosequencing of 16S rRNA genes retrieved five proteobacterial classes, and Bacteroidetes, Chlorobi, Chloroflexi, and Firmicutes phyla from all springs, which suggested the potential for a core sulfidic spring microbiome. Among the putative sulfide-oxidizing groups (Epsilonproteobacteria and Gammaproteobacteria, up to 83% of the sequences from geochemically similar springs clustered together. Abundant populations of Hydrogenimonas-like or Sulfurovum-like spp. (Epsilonproteobacteria occurred with abundant Thiothrix and Thiofaba spp. (Gammaproteobacteria, but Arcobacter-like and Sulfurimonas spp. (Epsilonproteobacteria occurred with less abundant gammaproteobacterial populations. These distribution patterns confirmed that geochemistry rather than biogeography regulates bacterial dominance at each spring. Potential biogeographic controls were related to paleogeologic sedimentation patterns that could control long-term microbial transport mechanisms that link surface and subsurface environments. Knowing the composition of a core sulfidic spring microbial community could provide a way to monitor diversity changes if a system is threatened by anthropogenic processes or

  19. Hydrogen sulfide and resolution of acute inflammation: A comparative study utilizing a novel fluorescent probe.

    Science.gov (United States)

    Dufton, Neil; Natividad, Jane; Verdu, Elena F; Wallace, John L

    2012-01-01

    Hydrogen sulfide is an essential gasotransmitter associated with numerous pathologies. We assert that hydrogen sulfide plays an important role in regulating macrophage function in response to subsequent inflammatory stimuli, promoting clearance of leukocyte infiltrate and reducing TNF-α levels in vivo following zymosan-challenge. We describe two distinct methods of measuring leukocyte hydrogen sulfide synthesis; methylene blue formation following zinc acetate capture and a novel fluorescent sulfidefluor probe. Comparison of these methods, using pharmacological tools, revealed they were complimentary in vitro and in vivo. We demonstrate the application of sulfidefluor probe to spectrofluorimetry, flow cytometry and whole animal imaging, to monitor the regulation of hydrogen sulfide synthesis in vivo during dynamic inflammatory processes. Both methodologies revealed that granulocyte infiltration negatively affects hydrogen sulfide synthesis. Our report offers an insight into the profile of hydrogen sulfide synthesis during inflammation and highlight opportunities raised by the development of novel fluorescent hydrogen sulfide probes.

  20. Blood Components Prevent Sulfide Poisoning of Respiration of the Hydrothermal Vent Tube Worm Riftia pachyptila

    Science.gov (United States)

    Powell, Mar A.; Somero, George N.

    1983-01-01

    Respiration of plume tissue of the hydrothermal vent tube worm Riftia pachyptila is insensitive to sulfide poisoning in contrast to tissues of animals that do not inhabit vents. Permeability barriers may not be responsible for this insensitivity since plume homogenates are also resistant to sulfide poisoning. Cytochrome c oxidase of plume, however, is strongly inhibited by sulfide at concentrations less than 10 μ M. Factors present in blood, but not in cytosol, prevent sulfide from inhibiting cytochrome c oxidase. Avoidance of sulfide poisoning of respiration in Riftia pachyptila thus appears to involve a blood-borne factor having a higher sulfide affinity than that of cytochrome c oxidase, with the result that appreciable amounts of free sulfide are prevented from accumulating in the blood and entering the intracellular compartment.

  1. Galvanic coupling and its effect on origin potential flotation system of sulfide minerals

    Institute of Scientific and Technical Information of China (English)

    顾帼华; 戴晶平; 王晖; 邱冠周

    2004-01-01

    The galvanic coupling formed in origin potential flotation systems of sulfide minerals can be divided into three types: sulfide mineral-sulfide mineral-water system; sulfide mineral-steel ball-water system; and sulfide mineral-sulfide mineral-collector system. In this paper, taking lead, zinc, iron sulfide mineral systems for examples,several models of galvanic coupling were proposed and the effects of galvanic coupling on flotation were discussed. A galvanic contact between galena (or sphalerite) and pyrite contributes to decreasing the content of zinc in lead concentrate, and enhances remarkably the absorption of collector on the galena surface. During grinding, due to galvanic interactions between minerals and steel medium, Fe(OH)3 formed covers on the cathodic mineral surface, affecting its floatability.

  2. Sulfur isotopic analysis of carbonyl sulfide and its application for biogeochemical cycles

    Science.gov (United States)

    Hattori, Shohei; Kamezaki, Kazuki; Ogawa, Takahiro; Toyoda, Sakae; Katayama, Yoko; Yoshida, Naohiro

    2016-04-01

    reaction does not contribute to the MIF signatures observed in sulfate aerosol samples and/or Archaean rock records. At the presentation, we report the comparison of 34ɛ values determined using some strains and the atmospheric implications for the OCS degradation in the present atmosphere are discussed. Hattori, S., Danielache, S. O., Johnson, M. S., Schmidt, J. A., Kjaergaard, H. G., Toyoda, S., Ueno, Y., Yoshida, N. Ultraviolet absorption cross sections of carbonyl sulfide isotopologues OC32S, OC33S, OC34S and O13CS: isotopic fractionation in photolysis and atmospheric implications, Atmos. Chem. Phys., 11, 10293-10303, 2011. Schmidt, J. A., Johnson, M. S., Jung, Y., Danielache, S. O., Hattori, S., Yoshida, N., Predictions of the sulfur and carbon kinetic isotope effects in the OH + OCS reaction, Chem. Phys. Lett., 531, 64-69, 2012. Hattori, S., Schmidt J. A., Mahler D., Danielache, S. O., Johnson M. S., Yoshida N. Isotope Effect in the Carbonyl Sulfide Reaction with O(3P), J. Phys. Chem. A, 116, 3521-3526, 2012. Hattori, S., Toyoda, A., Toyoda, S., Ishino S., Ueno, Y., Yoshida, N.: Determination of the Sulfur Isotope Ratio in Carbonyl Sulfide using Gas Chromatography/Isotope Ratio Mass Spectrometry on Fragment Ions 32S+, 33S+, and 34S+, Anal. Chem., 87, 477-484, 2015. Kato, H., Saito, M., Nagahata, Y., Katayama, Y.: Degradation of ambient carbonyl sulfide by Mycobacterium spp. in soil. Microbiol., 154(1), 249-255, 2008.

  3. Electrochemical Behavior of Sulfide at the Silver Rotating Disc Electrode. I. Polarization Behavior of Silver Sulfide Films.

    Science.gov (United States)

    1981-05-01

    from Reporf) C IS. SUPPLEMENTARY NOTES Prepared for publication in The Journal of Electroanalytical Chemistry 19. KEY WORDS (Continue on reverse aide it...SULFIDE FILMS by KUNIO SHIMIZU, KOICH AOKI AND ROBERT A. OSFERYOUNG Accepted for Publication in The Journal of Electroanalytical Chemistry Department

  4. Pyrite formation and mineral transformation pathways upon sulfidation of ferric hydroxides depend on mineral type and sulfide concentration

    NARCIS (Netherlands)

    Peiffer, Stefan; Behrends, Thilo; Hellige, Katrin; Larese-Casanova, Philip; Wan, Moli; Pollok, Kilian

    2015-01-01

    The reaction of ferric (hydr)oxides with dissolved sulfide does not lead to the instantaneous production of thermodynamically stable products but can induce a variety of mineral transformations including the formation of metastable intermediates. The importance of the various transformation pathways

  5. Neoproterozic Re-Os age of a sulfide inclusion in a superdeep diamond: Implications for mantle convection beneath Juina, Brazil

    Science.gov (United States)

    Shirey, S. B.; Smit, K.; Nestola, F.; Steele, A.; Bulanova, G.; Smith, C. B.

    2015-12-01

    Diamonds from the Juina area Brazil have long been known for their sublithospheric or superdeep (e.g. from depths of 300-800 km) origins. These diamonds have yielded new information about high pressure mantle mineralogy, deep crustal recycling, diamond source fluids, and mantle transition zone water content. A type II (low N) diamond (sample J1) from the 93.1±1.5 myr old (Heaman 7IKC 1998 ) Collier 4 kimberlite was studied previously (Walter et al. Nature 2008; Bulanova et al. CMP 2010) as part of a larger suite of eclogitic-composition, inclusion-bearing type II Collier 4 diamonds with complex internal growth structure. Major and trace element analyses of mineral inclusions in these diamonds include Ca-Ti-Si perovskite, Ca-rich majoritic-garnet, clinopyroxene, olivine, jeffbenite, minerals with stoichiometries of CAS and K-hollandite phases, SiO2, FeO, native iron, low-Ni sulfides, and Ca-Mg-carbonate. The C isotopic compositions of the diamond hosts range from a δ13C of -25 to -5‰ ( J1 being -15‰). Collier 4 diamonds have been interpreted to crystallize from carbonatitic melts derived from the recycling of oceanic lithosphere at TransitionZone depths (Walter et al. Nature 2008; Bulanova et al. CMP 2010). A rare Fe-sulfide inclusion in the core of diamond J1 has been dated with the Re-Os system in order to provide age and compositional constraints on the proposed oceanic slab recycling. The rim of J1 contained inclusions of Ca-Ti-Si perovskite that yielded U-Pb age of 101±7 Ma and eclogitic (low Cr, high Ca) majorite that yielded formation pressures (Si - Al+Cr geobarometry) >8 GPa (Bulanova et al. CMP 2010). The Fe-sulfide analyzed was low Ni pyrrhotite determined to be Fe10S11 of a rare 11T polytype by single-crystal X-ray diffraction. The 27 ug interior pyrrhotite had a high Re/Os (187Re/188Os = 854) typical of MORB (Re/Os ~100) and radiogenic Os isotopic composition (187Os/188Os = 8.50±1.38) that yields a 602±16 Ma model age relative to normal mantle

  6. Properties of iron sulfide, hydrosulfide, and mixed sulfide/hydrosulfide cluster anions through photoelectron spectroscopy and density functional theory calculations

    Science.gov (United States)

    Yin, Shi; Bernstein, Elliot R.

    2016-10-01

    A new magnetic-bottle time-of-flight photoelectron spectroscopy (PES) apparatus is constructed in our laboratory. The PES spectra of iron sulfide, hydrosulfide, and mixed sulfide/hydrosulfide [FeSm(SH)n-; m, n = 0-3, 0 theory. The most probable structures and ground state spin multiplicity for these cluster anions are tentatively assigned by comparing their theoretical first vertical detachment energies (VDEs) with their respective experiment values. The behavior of S and (SH) as ligands in these iron sulfide, hydrosulfide, and mixed sulfide/hydrosulfide cluster anions is investigated and compared. The experimental first VDEs for Fe(SH)1-3- cluster anions are lower than those found for their respective FeS1-3- cluster anions. The experimental first VDEs for FeS1-3- clusters are observed to increase for the first two S atoms bound to Fe-; however, due to the formation of an S-S bond for the FeS3- cluster, its first VDE is found to be ˜0.41 eV lower than the first VDE for the FeS2- cluster. The first VDEs of Fe(SH)1-3- cluster anions are observed to increase with the increasing numbers of SH groups. The calculated partial charges of the Fe atom for ground state FeS1-3- and Fe(SH)1-3- clusters are apparently related to and correlated with their determined first VDEs. The higher first VDE is correlated with a higher, more positive partial charge for the Fe atom of these cluster anions. Iron sulfide/hydrosulfide mixed cluster anions are also explored in this work: the first VDE for FeS(SH)- is lower than that for FeS2-, but higher than that for Fe(SH)2-; the first VDEs for FeS2(SH)- and FeS(SH)2- are close to that for FeS3-, but higher than that for Fe(SH)3-. The first VDEs of general iron sulfide, hydrosulfide, and mixed sulfide/hydrosulfide clusters [FeSm(SH)n-; m, n = 0-3, 0 < (m + n) ≤ 3] are dependent on three properties of these anions: 1. the partial charge on the Fe atom, 2. disulfide bond formation (S-S) in the cluster, and 3. the number of hydrosulfide

  7. Oxidation of chlorinated olefins by Escherichia coli transformed with dimethyl sulfide monooxygenase genes or cumene dioxygenase genes.

    Science.gov (United States)

    Takami, Wako; Yoshida, Takako; Nojiri, Hideaki; Yamane, Hisakazu; Omori, Toshio

    1999-04-01

    In the present work, it was shown that the dimethyl sulfide (DMS) monooxygenase and the cumene dioxygenase catalyzed oxidation of various chlorinated ethenes, propenes, and butenes. The specific activities of these oxygenases were determined for C(2) to C(4) chlorinated olefins, and the oxidation rates ranged from 0.19 to 4.18 nmol.min(-1).mg(-1) of dry cells by the DMS monooxygenase and from 0.19 to 1.29 nmol.min(-1).mg(-1) of dry cells by the cumene dioxygenase. The oxidation products were identified by gas chromatography-mass spectrometry. Most chlorinated olefins were monooxygenated by the DMS monooxygenase to yield chlorinated epoxides. In the case of the cumene dioxygenase, the substrates lacking any chlorine atom on double-bond carbon atoms were dioxygenated, and those with chlorine atoms attaching to double-bond carbon atoms were monooxygenated to yield allyl alcohols.

  8. Treatment and electricity harvesting from sulfate/sulfide-containing wastewaters using microbial fuel cell with enriched sulfate-reducing mixed culture

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Duu-Jong, E-mail: cedean@mail.ntust.edu.tw [Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan (China); Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan (China); Lee, Chin-Yu [Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan (China); Chang, Jo-Shu [Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan (China); Center for Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan (China); Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan, Taiwan (China)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer We started up microbial fuel cell (MFC) using enriched sulfate-reducing mixed culture. Black-Right-Pointing-Pointer Sulfate-reducing bacteria and anode-respiring bacteria were enriched in anodic biofilms. Black-Right-Pointing-Pointer The MFC effectively remove sulfate to elementary sulfur in the presence of lactate. Black-Right-Pointing-Pointer The present device can treat sulfate laden wastewaters with electricity harvesting. - Abstract: Anaerobic treatment of sulfate-laden wastewaters can produce excess sulfide, which is corrosive to pipelines and is toxic to incorporated microorganisms. This work started up microbial fuel cell (MFC) using enriched sulfate-reducing mixed culture as anodic biofilms and applied the so yielded MFC for treating sulfate or sulfide-laden wastewaters. The sulfate-reducing bacteria in anodic biofilm effectively reduced sulfate to sulfide, which was then used by neighboring anode respiring bacteria (ARB) as electron donor for electricity production. The presence of organic carbons enhanced MFC performance since the biofilm ARB were mixotrophs that need organic carbon to grow. The present device introduces a route for treating sulfate laden wastewaters with electricity harvesting.

  9. Extreme enrichment of Se, Te, PGE and Au in Cu sulfide microdroplets: evidence from LA-ICP-MS analysis of sulfides in the Skaergaard Intrusion, east Greenland

    Science.gov (United States)

    Holwell, David A.; Keays, Reid R.; McDonald, Iain; Williams, Megan R.

    2015-12-01

    The Platinova Reef, in the Skaergaard Intrusion, east Greenland, is an example of a magmatic Cu-PGE-Au sulfide deposit formed in the latter stages of magmatic differentiation. As is characteristic with such deposits, it contains a low volume of sulfide, displays peak metal offsets and is Cu rich but Ni poor. However, even for such deposits, the Platinova Reef contains extremely low volumes of sulfide and the highest Pd and Au tenor sulfides of any magmatic ore deposit. Here, we present the first LA-ICP-MS analyses of sulfide microdroplets from the Platinova Reef, which show that they have the highest Se concentrations (up to 1200 ppm) and lowest S/Se ratios (190-700) of any known magmatic sulfide deposit and have significant Te enrichment. In addition, where sulfide volume increases, there is a change from high Pd-tenor microdroplets trapped in situ to larger, low tenor sulfides. The transition between these two sulfide regimes is marked by sharp peaks in Au, and then Te concentration, followed by a wider peak in Se, which gradually decreases with height. Mineralogical evidence implies that there is no significant post-magmatic hydrothermal S loss and that the metal profiles are essentially a function of magmatic processes. We propose that to generate these extreme precious and semimetal contents, the sulfides must have formed from an anomalously metal-rich package of magma, possibly formed via the dissolution of a previously PGE-enriched sulfide. Other processes such as kinetic diffusion may have also occurred alongside this to produce the ultra-high tenors. The characteristic metal offset pattern observed is largely controlled by partitioning effects, producing offset peaks in the order Pt+Pd>Au>Te>Se>Cu that are entirely consistent with published D values. This study confirms that extreme enrichment in sulfide droplets can occur in closed-system layered intrusions in situ, but this will characteristically form ore deposits that are so low in sulfide that they do

  10. Trace elements in sulfide inclusions from Yakutian diamonds

    Science.gov (United States)

    Bulanova, G. P.; Griffin, W. L.; Ryan, C. G.; Shestakova, O. Y.; Barnes, S.-J.

    1996-07-01

    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

  11. Observed and calculated 1H and 13C chemical shifts induced by the in situ oxidation of model sulfides to sulfoxides and sulfones.

    Science.gov (United States)

    Dracínský, Martin; Pohl, Radek; Slavetínská, Lenka; Budesínský, Milos

    2010-09-01

    A series of model sulfides was oxidized in the NMR sample tube to sulfoxides and sulfones by the stepwise addition of meta-chloroperbenzoic acid in deuterochloroform. Various methods of quantum chemical calculations have been tested to reproduce the observed (1)H and (13)C chemical shifts of the starting sulfides and their oxidation products. It has been shown that the determination of the energy-minimized conformation is a very important condition for obtaining realistic data in the subsequent calculation of the NMR chemical shifts. The correlation between calculated and observed chemical shifts is very good for carbon atoms (even for the 'cheap' DFT B3LYP/6-31G* method) and somewhat less satisfactory for hydrogen atoms. The calculated chemical shifts induced by oxidation (the Delta delta values) agree even better with the experimental values and can also be used to determine the oxidation state of the sulfur atom (-S-, -SO-, -SO(2)-).

  12. Degradation of the pipe-steel structure upon long-term operation in contact with a hydrogen sulfide-containing medium

    Science.gov (United States)

    Schastlivtsev, V. M.; Tabatchnikova, T. I.; Tereshchenko, N. A.; Yakovleva, I. L.

    2011-03-01

    The phase composition and structure of defect portions of pipelines after long-term service in contact with a hydrogen sulfide-containing medium have been investigated. From structural changes, the process of the initiation of cracks and fracture of a low-carbon ferritic-pearlitic steel containing slag-induced laminations and precipitates of sulfides of the (Fe,Mn)S type has been reconstructed. The conditions under which a block cementite substructure is formed in the course of service and a transformation of the plate-type shape of the carbide phase occurs have been analyzed. It has been established that the dispersed carbides precipitating in this case limit the mobility of dislocations and thereby favor degradation of service properties of the pipe steel.

  13. Injection molding simulation with variothermal mold temperature control of highly filled polyphenylene sulfide

    Science.gov (United States)

    Birkholz, A.; Tschiersky, M.; Wortberg, J.

    2015-05-01

    For the installation of a fuel cell stack to convert chemical energy into electricity it is common to apply bipolar plates to separate and distribute reaction gases and cooling agents. For reducing manufacturing costs of bipolar plates a fully automated injection molding process is examined. The high performance thermoplastic matrix material, polyphenylene sulfide (PPS), defies against the chemical setting and the operation temperature up to 200 °C. To adjust also high electrical and thermal conductivity, PPS is highly filled with various carbon fillers up to an amount of 65 percentage by volume. In the first step two different structural plates (one-sided) with three different gate heights and molds are designed according to the characteristics of a bipolar plate. To cope with the approach that this plate should be producible on standard injection molding machines with variothermal mold temperature control, injection molding simulation is used. Additionally, the simulation should allow to formulate a quality prediction model, which is transferrable to bipolar plates. Obviously, the basis for a precise simulation output is an accurate description of the material properties and behavior of the highly filled compound. This, the design of the structural plate and mold and the optimization via simulation is presented, as well. The influence of the injection molding process parameters, e.g. injection time, cycle times, packing pressure, mold temperature, and melt temperature on the form filling have been simulated to determine optimal process conditions. With the aid of the simulation and the variothermal mold temperature control it was possible to reduce the required melt temperature below the decomposition temperature of PPS. Thereby, hazardous decomposition products as hydrogen sulfide are obviated. Thus, the health of the processor, the longevity of the injection molding machine as well as the material and product properties can be protected.

  14. Metal oxide and mercuric sulfide nanoparticles synthesis and characterization

    Science.gov (United States)

    Xu, Xin

    Commercially available and laboratory-synthesized metal based nanoparticles (NPs), iron oxide (Fe2O3), copper oxide (CuO), titanium dioxide (TiO2), zinc oxide (ZnO) and mercuric sulfide (HgS) were studied by comprehensive characterizations methods. The general synthesis process was modified sol-gel method. The size and morphology of NPs could be influenced by temperature, sonication, calcination, precursor concentration, pH and types of reaction media. All types of the laboratory-synthesized or commercially available NPs were characterized by physical and chemical processes. One characteristic of NP that can lead to ambiguous toxicity test results was the effect of agglomeration of primary nano-sized particles. Laser light scattering was used to measure the aggregated and particle size distribution. Aggregation effects were apparent and often extensive in some synthesis approaches. Electron microscopy (SEM and TEM) gave the images of those laboratory-synthesized particles and aggregation. The average single particle was about 5-20 nm of ZnO; 20-40 nm of CuO; 10-20 nm of TiO2; 20-35 nm of Fe2O3; 10-15 nm of HgS, while the aggregate size was in the range of a hundred nanometers or more. These five types of NPs were obtained with spherical and oblong formation and the agglomeration of ZnO, CuO, HgS and TiO2 was random, but Fe2O3 has web-like aggregation. Other measurements performed on the particles and aggregates include bandgap energies, surface composition, surface area, hydrodynamic radius, and particle surface charge. In aqueous environment, NPs are subject to processes such as solubilization and aggregation. These processes can be controlling factors in the fate of nanomaterials in environmental settings, including bioavailability to organisms. This study has focused primarily on measurement of the solubility in aqueous media of varying composition (pH, ionic strength, and organic carbon), sedimentation and stability. The aggregate size distribution was

  15. Hydrogen sulfide inhalation ameliorates allergen induced airway hypereactivity by modulating mast cell activation.

    Science.gov (United States)

    Roviezzo, Fiorentina; Bertolino, Antonio; Sorrentino, Rosalinda; Terlizzi, Michela; Matteis, Maria; Calderone, Vincenzo; Mattera, Valentina; Martelli, Alma; Spaziano, Giuseppe; Pinto, Aldo; D'Agostino, Bruno; Cirino, Giuseppe

    2015-10-01

    Compelling evidence suggests that hydrogen sulfide represents an important gaseous transmitter in the mammalian respiratory system. In the present study, we have evaluated the role of mast cells in hydrogen sulfide-induced effects on airways in a mouse model of asthma. Mice were sensitized to ovalbumin and received aerosol of a hydrogen sulfide donor (NaHS; 100 ppm) starting at day 7 after ovalbumin challenge. Exposure to hydrogen sulfide abrogated ovalbumin-induced bronchial hypereactivity as well as the increase in lung resistance. Concomitantly, hydrogen sulfide prevented mast cell activity as well as FGF-2 and IL-13 upregulation. Conversely, pulmonary inflammation and the increase in plasmatic IgE levels were not affected by hydrogen sulfide. A lack of hydrogen sulfide effects in mast cell deficient mice occurred. Primary fibroblasts harvested from ovalbumin-sensitized mice showed an increased proliferation rate that was inhibited by hydrogen sulfide aerosol. Furthermore, ovalbumin-induced transdifferentiation of pulmonary fibroblasts into myofibroblasts was reversed. Finally, hydrogen sulfide did abrogate in vitro the degranulation of the mast cell-like RBL-2H3 cell line. Similarly to the in vivo experiments the inhibitory effect was present only when the cells were activated by antigen exposure. In conclusion, inhaled hydrogen sulfide improves lung function and inhibits bronchial hyper-reactivity by modulating mast cells and in turn fibroblast activation.

  16. Influence of pipe material and surfaces on sulfide related odor and corrosion in sewers.

    Science.gov (United States)

    Nielsen, Asbjørn Haaning; Vollertsen, Jes; Jensen, Henriette Stokbro; Wium-Andersen, Tove; Hvitved-Jacobsen, Thorkild

    2008-09-01

    Hydrogen sulfide oxidation on sewer pipe surfaces was investigated in a pilot scale experimental setup. The experiments were aimed at replicating conditions in a gravity sewer located immediately downstream of a force main where sulfide related concrete corrosion and odor is often observed. During the experiments, hydrogen sulfide gas was injected intermittently into the headspace of partially filled concrete and plastic (PVC and HDPE) sewer pipes in concentrations of approximately 1,000 ppm(v). Between each injection, the hydrogen sulfide concentration was monitored while it decreased because of adsorption and subsequent oxidation on the pipe surfaces. The experiments showed that the rate of hydrogen sulfide oxidation was approximately two orders of magnitude faster on the concrete pipe surfaces than on the plastic pipe surfaces. Removal of the layer of reaction (corrosion) products from the concrete pipes was found to reduce the rate of hydrogen sulfide oxidation significantly. However, the rate of sulfide oxidation was restored to its background level within 10-20 days. A similar treatment had no observable effect on hydrogen sulfide removal in the plastic pipe reactors. The experimental results were used to model hydrogen sulfide oxidation under field conditions. This showed that the gas-phase hydrogen sulfide concentration in concrete sewers would typically amount to a few percent of the equilibrium concentration calculated from Henry's law. In the plastic pipe sewers, significantly higher concentrations were predicted because of the slower adsorption and oxidation kinetics on such surfaces.

  17. Influence of sulfide concentration on the corrosion behavior of titanium in a simulated oral environment.

    Science.gov (United States)

    Harada, Rino; Takemoto, Shinji; Kinoshita, Hideaki; Yoshinari, Masao; Kawada, Eiji

    2016-05-01

    This study assessed the corrosion behavior of titanium in response to sulfide by determining the effects of sulfide concentration and pH over immersion period. Corrosion was evaluated through changes in color, glossiness, surface characterization, and titanium release. Sulfide solutions were prepared in 3 different concentrations with Na2S, each in pH unadjusted (sulfide-alkaline) and pH adjusted to 7.5 (sulfide-neutral). Titanium discoloration increased and glossiness decreased as sulfide concentration and immersion period increased in sulfide-alkaline solutions. Coral-like complexes were observed on the surface of these specimens, which became more pronounced as concentration increased. Small amounts of titanium release were detected in sulfide-alkaline solutions; however, this was not affected by immersion periods. Corrosion was indicated through considerable surface oxidation suggesting the formation of a thick oxide layer. No significant changes in color and glossiness, or titanium release were indicated for titanium specimens immersed in sulfide-neutral solutions indicating that pH had a significant effect on corrosion. Our findings suggest that a thick oxide layer on the titanium surface was formed in sulfide-alkaline solutions due to excessive oxidation.

  18. The removal of hydrogen sulfide from gas streams using an aqueous metal sulfate absorbent : Part II. the regeneration of copper sulfide to copper oxide - An experimental study

    NARCIS (Netherlands)

    Ter Maat, H.; Hogendoorn, J. A.; Versteeg, G. F.

    2005-01-01

    Aim of this study was to investigate the possibilities for a selective and efficient method to convert copper(II) sulfide (CuS) into copper(II) oxide (CuO). The oxidation of copper sulfide has been studied experimentally using a thermogravimetric analyzer (TGA) at temperatures ranging from 450 to 75

  19. The removal of hydrogen sulfide from gas streams using an aqueous metal sulfate absorbent: Part II. The regeneration of copper sulfide to copper oxide—an experimental study

    NARCIS (Netherlands)

    Maat, ter H.; Hogendoorn, J.A.; Versteeg, G.F.

    2005-01-01

    Aim of this study was to investigate the possibilities for a selective and efficient method to convert copper(II) sulfide (CuS) into copper(II) oxide (CuO). The oxidation of copper sulfide has been studied experimentally using a thermogravimetric analyzer (TGA) at temperatures ranging from 450 to 75

  20. Anoxygenic Photosynthesis Controls Oxygenic Photosynthesis in a Cyanobacterium from a Sulfidic Spring

    KAUST Repository

    Klatt, Judith M.

    2015-03-15

    Before the Earth\\'s complete oxygenation (0.58 to 0.55 billion years [Ga] ago), the photic zone of the Proterozoic oceans was probably redox stratified, with a slightly aerobic, nutrient-limited upper layer above a light-limited layer that tended toward euxinia. In such oceans, cyanobacteria capable of both oxygenic and sulfide-driven anoxygenic photosynthesis played a fundamental role in the global carbon, oxygen, and sulfur cycle. We have isolated a cyanobacterium, Pseudanabaena strain FS39, in which this versatility is still conserved, and we show that the transition between the two photosynthetic modes follows a surprisingly simple kinetic regulation controlled by this organism\\'s affinity for H2S. Specifically, oxygenic photosynthesis is performed in addition to anoxygenic photosynthesis only when H2S becomes limiting and its concentration decreases below a threshold that increases predictably with the available ambient light. The carbon-based growth rates during oxygenic and anoxygenic photosynthesis were similar. However, Pseudanabaena FS39 additionally assimilated NO3 - during anoxygenic photosynthesis. Thus, the transition between anoxygenic and oxygenic photosynthesis was accompanied by a shift of the C/N ratio of the total bulk biomass. These mechanisms offer new insights into the way in which, despite nutrient limitation in the oxic photic zone in the mid-Proterozoic oceans, versatile cyanobacteria might have promoted oxygenic photosynthesis and total primary productivity, a key step that enabled the complete oxygenation of our planet and the subsequent diversification of life.

  1. Anoxygenic photosynthesis controls oxygenic photosynthesis in a cyanobacterium from a sulfidic spring.

    Science.gov (United States)

    Klatt, Judith M; Al-Najjar, Mohammad A A; Yilmaz, Pelin; Lavik, Gaute; de Beer, Dirk; Polerecky, Lubos

    2015-03-01

    Before the Earth's complete oxygenation (0.58 to 0.55 billion years [Ga] ago), the photic zone of the Proterozoic oceans was probably redox stratified, with a slightly aerobic, nutrient-limited upper layer above a light-limited layer that tended toward euxinia. In such oceans, cyanobacteria capable of both oxygenic and sulfide-driven anoxygenic photosynthesis played a fundamental role in the global carbon, oxygen, and sulfur cycle. We have isolated a cyanobacterium, Pseudanabaena strain FS39, in which this versatility is still conserved, and we show that the transition between the two photosynthetic modes follows a surprisingly simple kinetic regulation controlled by this organism's affinity for H2S. Specifically, oxygenic photosynthesis is performed in addition to anoxygenic photosynthesis only when H2S becomes limiting and its concentration decreases below a threshold that increases predictably with the available ambient light. The carbon-based growth rates during oxygenic and anoxygenic photosynthesis were similar. However, Pseudanabaena FS39 additionally assimilated NO3 (-) during anoxygenic photosynthesis. Thus, the transition between anoxygenic and oxygenic photosynthesis was accompanied by a shift of the C/N ratio of the total bulk biomass. These mechanisms offer new insights into the way in which, despite nutrient limitation in the oxic photic zone in the mid-Proterozoic oceans, versatile cyanobacteria might have promoted oxygenic photosynthesis and total primary productivity, a key step that enabled the complete oxygenation of our planet and the subsequent diversification of life.

  2. Crustal contamination and sulfide immiscibility history of the Permian Huangshannan magmatic Ni-Cu sulfide deposit, East Tianshan, NW China

    Science.gov (United States)

    Mao, Ya-Jing; Qin, Ke-Zhang; Tang, Dong-Mei; Feng, Hong-Ye; Xue, Sheng-Chao

    2016-11-01

    The Huangshannan mafic-ultramafic intrusion is a Permian Ni-Cu sulfide-bearing intrusion in the southern margin of the Central Asian Orogenic Belt. The intrusion consists of an ultramafic unit, which is composed of lherzolite and olivine websterite, and a mafic unit, which is composed of olivine gabbronorite, gabbronorite and leuco-gabbronorite. This intrusion was formed by two separate pulses of magma: a more primitive magma for the early ultramafic unit and a more evolved magma for the late mafic unit. U-Pb isotope geochronology of zircon from the mafic unit yields an age of 278 ± 2 Ma. According to its olivine and Cr-rich spinel compositions, the estimated parental magma of lherzolite for the Huangshannan intrusion has 12.4 wt.% MgO, indicating picritic affinity. Fractional crystallization modeling results and the presence of rounded sulfide inclusions in an olivine crystal (Fo 86.7) indicate that sulfide immiscibility was achieved at the beginning of olivine fractionation. Co-magmatic zircon crystals from gabbronorite have a δ18O value close to 6.5‰, which is 1.2‰ higher than the typical mantle value and suggests significant crustal contamination (∼20%). The positive εHf(t) values of co-magmatic zircon (which vary from +9.2 to +15.3) and positive whole rock εNd(t) values (which vary from +4.7 to +7.8) also indicate that the parental magma was derived from a depleted mantle source and contaminated by 5-20% juvenile arc crust and then by ∼5% upper crustal materials. However, modeling results of sulfur content at sulfide saturation reveal that such a large amount of crustal contamination is not sufficient to trigger sulfide saturation in the parental magma, which strongly suggests that external sulfur addition, probably during contamination, has played a critical role in causing sulfide immiscibility. Furthermore, the arc magmatism geochemical signatures of the Huangshannan intrusion, such as significant Nb and Ta depletion relative to La and low Ca

  3. L-Cysteine-assisted Synthesis of Copper Gallium Sulfide Microspheres

    Institute of Scientific and Technical Information of China (English)

    LIANG Xiao-juan; ZHONG Jia-song; CAI Qian; HUANG Hai-yu; LIU Hai-tao; XIANG Wei-dong; SUN Jun-cai

    2012-01-01

    An effective L-cysteine-assisted synthetic route has been successfully developed to prepare copper gallium sulfide(CuGaS2) microspheres under solvothermal conditions with CuCI2-2H2O,GaCl3 and L-cysteine as source materials,in which L-cysteine was used as the sulfide source and eomplexing molecule.The experiments revealed that the synthesized sample was of a typical CuGaS2 tetragonal structure.Moreover,the prepared CuGaS2 crystals consisting of microspheres made up of nanoflakes,and the diameter of the nanoflakes was about 20 nm.Raman spectrum of the obtained CuGaS2 exhibits a high-intensity peak of the A1 mode at 306 cm-1.Meanwhile,a possible growth mechanism was proposed based on the investigations.

  4. Oxygen-free atomic layer deposition of indium sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Martinson, Alex B.; Hock, Adam S.; McCarthy, Robert; Weimer, Matthew S.

    2016-07-05

    A method for synthesizing an In(III) N,N'-diisopropylacetamidinate precursor including cooling a mixture comprised of diisopropylcarbodiimide and diethyl ether to approximately -30.degree. C., adding methyllithium drop-wise into the mixture, allowing the mixture to warm to room temperature, adding indium(III) chloride as a solid to the mixture to produce a white solid, dissolving the white solid in pentane to form a clear and colorless solution, filtering the mixture over a celite plug, and evaporating the solution under reduced pressure to obtain a solid In(III) N,N'-diisopropylacetamidinate precursor. This precursor has been further used to develop a novel atomic layer deposition technique for indium sulfide by dosing a reactor with the precursor, purging with nitrogen, dosing with dilute hydrogen sulfide, purging again with nitrogen, and repeating these steps to increase growth.

  5. LUMINESCENCE OF CADMIUM SULFIDE QUANTUM DOTS IN FLUOROPHOSPHATE GLASSES

    Directory of Open Access Journals (Sweden)

    Z. O. Lipatova

    2015-03-01

    Full Text Available Cadmium sulfide quantum dots are perspective materials in optics, medicine, biology and optoelectronics. Fluorophosphate glasses, doped with cadmium sulfide quantum dots, were examined in the paper. Heat treatment led to the formation of quantum dots with diameters equal to 2.8 nm, 3.0 nm and 3.8 nm. In view of such changes in the quantum dots size the fundamental absorption edge shift and the luminescence band are being displaced to the long wavelengths. Luminescence lifetime has been found to be dependent on the registration wavelength in the range from 450 to 700 nm. Obtained fluorophosphate glasses with CdS quantum dots can find their application as fluorescent materials with intensive luminescence band and long excited-state natural lifetime.

  6. Effect of hydrogen sulfide emissions on cement mortar specimens

    Energy Technology Data Exchange (ETDEWEB)

    Idriss, A. F. [Alberta Environment, Science and Technology Branch, Edmonton, AB (Canada); Negi, S. C.; Jofriet, J. C.; Haywoard, G. L. [Guelph Univ., Guelph, ON (Canada)

    2001-07-01

    Six different cement mortar specimens used in animal buildings, where they were exposed to hydrogen sulfide generated from anaerobic fermentation of manure during a period of one year, were investigated. Primary interest was on comparing the corrosion resistance of different cement mortar specimens under long term exposure to hydrogen sulfide. The impressed voltage technique was used to test the specimens in the laboratory. Results revealed that test specimens made with eight per cent silica fume cement replacement performed best and similar Portland cement mortar specimens with a water-cement ratio of 0.55 (PC55) the poorest. All other treatments, (Portland cement with a water to cement ratio of 045, Portland cement Type 50, Portland cement with fibre mesh and Portland cement Type 10 coated with linseed oil) all with water-cement ratios of 0.45, were less effective in preventing corrosion than silica fume replacement.

  7. Fractal characteristics of nanocrystalline indium and gallium sulfide particles

    Energy Technology Data Exchange (ETDEWEB)

    Sastry, P.U., E-mail: psastry@barc.gov.i [Solid State Physics Division, Mumbai 400085 (India); Dutta, Dimple P. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2009-11-13

    The structure of nano-sized powders of indium sulfide (In{sub 2}S{sub 3}) and gallium sulfide (Ga{sub 2}S{sub 3}), prepared by single source precursor route has been investigated by small angle X-ray scattering technique. The particle morphology shows interesting fractal nature. For In{sub 2}S{sub 3}, the nanoparticle aggregates show a mass fractal with fractal dimension 2.0 that increases with longer time of thermal treatment. Below the length scale of about 20 nm, the particles have a rough surface with a surface fractal dimension of 2.8. Unlike In{sub 2}S{sub 3}, structure of Ga{sub 2}S{sub 3} exhibits a single surface fractal over whole q-range of study. The estimated particle sizes are in range of 5-15 nm and the results are supported by transmission electron microscope.

  8. Hydrogen sulfide determines HNO-induced stimulation of trigeminal afferents.

    Science.gov (United States)

    Wild, Vanessa; Messlinger, Karl; Fischer, Michael J M

    2015-08-18

    Endogenous NO and hydrogen sulfide form HNO, which causes CGRP release via TRPA1 channel activation in sensory nerves. In the present study, stimulation of intact trigeminal afferent neuron preparations with NO donors, Na2S or both was analyzed by measuring CGRP release as an index of mass activation. Combined stimulation was able to activate all parts of the trigeminal system and acted synergistic compared to stimulation with both substances alone. To investigate the contribution of both substances, we varied their ratio and tracked intracellular calcium in isolated neurons. Our results demonstrate that hydrogen sulfide is the rate-limiting factor for HNO formation. CGRP has a key role in migraine pathophysiology and HNO formation at all sites of the trigeminal system should be considered for this novel means of activation.

  9. 'Low-acid' sulfide oxidation using nitrate-enriched groundwater

    Science.gov (United States)

    Donn, Michael; Boxall, Naomi; Reid, Nathan; Meakin, Rebecca; Gray, David; Kaksonen, Anna; Robson, Thomas; Shiers, Denis

    2016-04-01

    Acid drainage (AMD/ARD) is undoubtedly one of the largest environmental, legislative and economic challenges facing the mining industry. In Australia alone, at least 60m is spent on AMD related issues annually, and the global cost is estimated to be in the order of tens of billions US. Furthermore, the challenge of safely and economically storing or treating sulfidic wastes will likely intensify because of the trend towards larger mines that process increasingly higher volumes of lower grade ores and the associated sulfidic wastes and lower profit margins. While the challenge of managing potentially acid forming (PAF) wastes will likely intensify, the industrial approaches to preventing acid production or ameliorating the effects has stagnated for decades. Conventionally, PAF waste is segregated and encapsulated in non-PAF tips to limit access to atmospheric oxygen. Two key limitations of the 'cap and cover' approach are: 1) the hazard (PAF) is not actually removed; only the pollutant linkage is severed; and, 2) these engineered structures are susceptible to physical failure in short-to-medium term, potentially re-establishing that pollutant linkage. In an effort to address these concerns, CSIRO is investigating a passive, 'low-acid' oxidation mechanism for sulfide treatment, which can potentially produce one quarter as much acidity compared with pyrite oxidation under atmospheric oxygen. This 'low-acid' mechanism relies on nitrate, rather than oxygen, as the primary electron accepter and the activity of specifically cultured chemolithoautotrophic bacteria and archaea communities. This research was prompted by the observation that, in deeply weathered terrains of Australia, shallow (oxic to sub-oxic) groundwater contacting weathering sulfides are commonly inconsistent with the geochemical conditions produced by ARD. One key characteristic of these aquifers is the natural abundance of nitrate on a regional scale, which becomes depleted around the sulfide bodies, and

  10. Synthesis and characterization of cerium sulfide thin film

    Institute of Scientific and Technical Information of China (English)

    Ιshak Afsin Kariper

    2014-01-01

    Cerium sulfide (CexSy) polycrystalline thin film is coated with chemical bath deposition on substrates (commercial glass). Transmittance, absorption, optical band gap and refractive index are examined by using UV/VIS. Spectrum. The hexagonal form is observed in the structural properties in XRD. The structural and optical properties of cerium sulfide thin films are analyzed at different pH. SEM and EDX analyses are made for surface analysis and elemental ratio in films. It is observed that some properties of films changed with different pH values. In this study, the focus is on the observed changes in the properties of films. The pH values were scanned at 6–10. The optical band gap changed with pH between 3.40 to 3.60 eV. In addition, the film thickness changed with pH at 411 nm to 880 nm.

  11. Fabrication and applications of copper sulfide (CuS) nanostructures

    Science.gov (United States)

    Shamraiz, Umair; Hussain, Raja Azadar; Badshah, Amin

    2016-06-01

    This review article presents different fabrication procedures (under the headlines of solvothermal routes, aerosol methods, solution methods and thermolysis), and applications (photocatalytic degradation, ablation of cancer cells, electrode material in lithium ion batteries and in gas sensing, organic solar cells, field emission properties, super capacitor applications, photoelectrochemical performance of QDSCs, photocatalytic reduction of organic pollutants, electrochemical bio sensing, enhanced PEC characteristics of pre-annealed CuS film electrodes) of copper sulfide (Covellite).

  12. Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

    Directory of Open Access Journals (Sweden)

    Vladimir N. Boiko

    2010-08-01

    Full Text Available This review covers all of the common methods for the syntheses of aromatic and heterocyclic perfluoroalkyl sulfides, a class of compounds which is finding increasing application as starting materials for the preparation of agrochemicals, pharmaceutical products and, more generally, fine chemicals. A systematic approach is taken depending on the mode of incorporation of the SRF groups and also on the type of reagents used.

  13. Laboratory SIP signatures associated with oxidation of disseminated metal sulfides

    Science.gov (United States)

    Placencia-Gómez, Edmundo; Slater, Lee; Ntarlagiannis, Dimitrios; Binley, Andrew

    2013-05-01

    Oxidation of metal sulfide minerals is responsible for the generation of acidic waters rich in sulfate and metals. When associated with the oxidation of sulfide ore mine waste deposits the resulting pore water is called acid mine drainage (AMD); AMD is a known environmental problem that affects surface and ground waters. Characterization of oxidation processes in-situ is challenging, particularly at the field scale. Geophysical techniques, spectral induced polarization (SIP) in particular, may provide a means of such investigation. We performed laboratory experiments to assess the sensitivity of the SIP method to the oxidation mechanisms of common sulfide minerals found in mine waste deposits, i.e., pyrite and pyrrhotite, when the primary oxidant agent is dissolved oxygen. We found that SIP parameters, e.g., phase shift, the imaginary component of electrical conductivity and total chargeability, decrease as the time of exposure to oxidation and oxidation degree increase. This observation suggests that dissolution-depletion of the mineral surface reduces the capacitive properties and polarizability of the sulfide minerals. However, small increases in the phase shift and imaginary conductivity do occur during oxidation. These transient increases appear to correlate with increases of soluble oxidizing products, e.g., Fe2 + and Fe3 + in solution; precipitation of secondary minerals and the formation of a passivating layer to oxidation coating the mineral surface may also contribute to these increases. In contrast, the real component of electrical conductivity associated with electrolytic, electronic and interfacial conductance is sensitive to changes in the pore fluid chemistry as a result of the soluble oxidation products released (Fe2 + and Fe3 +), particularly for the case of pyrrhotite minerals.

  14. Reconstruction of the electron spectrum in a metal hydrogen sulfide

    Science.gov (United States)

    Kudryashov, N. A.; Kutukov, A. A.; Mazur, E. A.

    2017-01-01

    Generalized Eliashberg theory of the normal properties of a metal electron-phonon system with a non constant electron density of states has been used to study the effect of the conduction band reconstruction. The electron density of states of the metallic phase of the hydrogen sulfide renormalized by the strong electron-phonon coupling at a pressure of P = 225 GPa has been calculated. It has been found that the reconstructed conduction band contains a series of narrow energy pockets.

  15. Hydrogen sulfide metabolism regulates endothelial solute barrier function

    Directory of Open Access Journals (Sweden)

    Shuai Yuan

    2016-10-01

    Full Text Available Hydrogen sulfide (H2S is an important gaseous signaling molecule in the cardiovascular system. In addition to free H2S, H2S can be oxidized to polysulfide which can be biologically active. Since the impact of H2S on endothelial solute barrier function is not known, we sought to determine whether H2S and its various metabolites affect endothelial permeability. In vitro permeability was evaluated using albumin flux and transendothelial electrical resistance. Different H2S donors were used to examine the effects of exogenous H2S. To evaluate the role of endogenous H2S, mouse aortic endothelial cells (MAECs were isolated from wild type mice and mice lacking cystathionine γ-lyase (CSE, a predominant source of H2S in endothelial cells. In vivo permeability was evaluated using the Miles assay. We observed that polysulfide donors induced rapid albumin flux across endothelium. Comparatively, free sulfide donors increased permeability only with higher concentrations and at later time points. Increased solute permeability was associated with disruption of endothelial junction proteins claudin 5 and VE-cadherin, along with enhanced actin stress fiber formation. Importantly, sulfide donors that increase permeability elicited a preferential increase in polysulfide levels within endothelium. Similarly, CSE deficient MAECs showed enhanced solute barrier function along with reduced endogenous bound sulfane sulfur. CSE siRNA knockdown also enhanced endothelial junction structures with increased claudin 5 protein expression. In vivo, CSE genetic deficiency significantly blunted VEGF induced hyperpermeability revealing an important role of the enzyme for barrier function. In summary, endothelial solute permeability is critically regulated via exogenous and endogenous sulfide bioavailability with a prominent role of polysulfides.

  16. Delivering carbide ligands to sulfide-rich clusters.

    Science.gov (United States)

    Reinholdt, Anders; Herbst, Konrad; Bendix, Jesper

    2016-02-01

    The propensity of the terminal ruthenium carbide Ru(C)Cl2(PCy3)2 (RuC) to form carbide bridges to electron-rich transition metals enables synthetic routes to metal clusters with coexisting carbide and sulfide ligands. Electrochemical experiments show the Ru≡C ligand to exert a relatively large electron-withdrawing effect compared with PPh3, effectively shifting redox potentials.

  17. Benzothiazole sulfide compatibilized polypropylene/halloysite nanotubes composites

    Energy Technology Data Exchange (ETDEWEB)

    Liu Mingxian [Department of Polymer Materials and Engineering, South China University of Technology, Guangzhou 510640 (China); Guo Baochun, E-mail: psbcguo@scut.edu.cn [Department of Polymer Materials and Engineering, South China University of Technology, Guangzhou 510640 (China); Lei Yanda; Du Mingliang; Jia Demin [Department of Polymer Materials and Engineering, South China University of Technology, Guangzhou 510640 (China)

    2009-02-15

    Clay-philic benzothiazole sulfide, capable of donating electrons, is grafted onto polypropylene (PP) backbones when N-cyclohexyl-2-benzothiazole sulfonamide (CBS), a commonly used accelerator in the tire industry, is included in the processing of PP/halloysite nanotubes (HNTs) composites. CBS decomposes at elevated temperature and yields benzothiazole sulfide radicals, which react with the PP polymeric free radicals generated during the processing of the composites. On the other hand, the benzothiazole group of CBS is reactive to HNTs via electron transferring. The compatibilization between HNTs and PP is thus realized via interfacial grafting and electron transferring mechanism. The interfacial interactions in the compatibilized systems were fully characterized. Compared with the control sample, the dispersion of HNTs and the interfacial bonding are enhanced substantially in the compatibilized composites. The significantly improved mechanical properties and thermal properties of benzothiazole sulfide compatibilized PP/HNTs composites are correlated to the enhanced interfacial property. The present work demonstrates a novel interfacial design via interfacial grafting/electron transferring for the compatibilization of PP/clay composites.

  18. Chemical Precipitation Synthesis and Thermoelectric Properties of Copper Sulfide

    Science.gov (United States)

    Wu, Sixin; Jiang, Jing; Liang, Yinglin; Yang, Ping; Niu, Yi; Chen, Yide; Xia, Junfeng; Wang, Chao

    2017-04-01

    Earth-abundant copper sulfide compounds have been intensively studied as potential thermoelectric materials due to their high dimensionless figure of merit ZT values. They have a unique phonon-liquid electron-crystal model that helps to achieve high thermoelectric performance. Many methods, such as melting and ball-milling, have been adopted to synthesize this copper sulfide compound, but they both use expensive starting materials with high purity. Here, we develop a simple chemical precipitation approach to synthesize copper sulfide materials through low-cost analytically pure compounds as the starting materials. A high ZT value of 0.93 at 800 K was obtained from the samples annealed at 1273 K. Its power factor is around 8.0 μW cm-1 K-2 that is comparable to the highest record reported by traditional methods. But, the synthesis here has been greatly simplified with reduced cost, which will be of great benefit to the potential mass production of thermoelectric devices. Furthermore, this method can be applied to the synthesis of other sulfur compound thermoelectric materials.

  19. Impact electrochemistry: colloidal metal sulfide detection by cathodic particle coulometry.

    Science.gov (United States)

    Lim, Chee Shan; Pumera, Martin

    2015-10-28

    The determination of the size and concentration of colloidal nano and microparticles is of paramount importance to modern nanoscience. Application of the particle collision technique on metal and metal oxide nanoparticles has been intensively explored over the past decade owing to its ability to determine the particle size and concentration via reactions including the inherent oxidation or the reduction of nanoparticles as well as surface reactions catalysed by the nanoparticles. Transition metal dichalcogenide particles were previously quantified using the anodic (oxidative) particle coulometry method. Here we show that cathodic (reductive) particle coulometry can be favorably used for the detection of metal sulfide colloidal particles. The detection of sulfides of cobalt and lead was performed using the particle collision technique in this work. The presence of spikes confirmed the viability of detecting new and larger particles from compounds using reductive (cathodic) potentials. Such an expansion of the impact particle coulometry method will be useful and applicable to the determination of concentration and size of colloidal metal sulfide nanoparticles in general.

  20. Structural studies of copper sulfide films: effect of ambient atmosphere

    Directory of Open Access Journals (Sweden)

    Manisha Kundu et al

    2008-01-01

    Full Text Available We examined the structural properties of copper sulfide films as a function of the sulfurization time of 70-nm-thick Cu films. Copper sulfide films with various phases such as mixed metallic Cu-chalcocite, chalcocite, roxbyite, and covellite phases were formed with increasing sulfurization time. To evaluate the structural stability of various films, all the films were exposed to the ambient atmosphere for the same amount of time. Although the phase structure and stoichiometry of the films were maintained at a greater depth, the near-surface region of the films was oxidized and covered with overlayers of oxide, hydroxide, and/or sulfate species due to the exposure and reaction with the ambient atmosphere. The oxygen uptake and its reactivity with the copper sulfide film surfaces were enhanced with increasing sulfur content of the films. In addition, the type of divalent state of copper formed on the film surfaces depended on the phase structure, composition, and stoichiometry of the films.

  1. Protective Effects of Hydrogen Sulfide in the Ageing Kidney.

    Science.gov (United States)

    Hou, Cui-Lan; Wang, Ming-Jie; Sun, Chen; Huang, Yong; Jin, Sheng; Mu, Xue-Pan; Chen, Ying; Zhu, Yi-Chun

    2016-01-01

    Aims. The study aimed to examine whether hydrogen sulfide (H2S) generation changed in the kidney of the ageing mouse and its relationship with impaired kidney function. Results. H2S levels in the plasma, urine, and kidney decreased significantly in ageing mice. The expression of two known H2S-producing enzymes in kidney, cystathionine γ-lyase (CSE) and cystathionine-β-synthase (CBS), decreased significantly during ageing. Chronic H2S donor (NaHS, 50 μmol/kg/day, 10 weeks) treatment could alleviate oxidative stress levels and renal tubular interstitial collagen deposition. These protective effects may relate to transcription factor Nrf2 activation and antioxidant proteins such as HO-1, SIRT1, SOD1, and SOD2 expression upregulation in the ageing kidney after NaHS treatment. Furthermore, the expression of H2S-producing enzymes changed with exogenous H2S administration and contributed to elevated H2S levels in the ageing kidney. Conclusions. Endogenous hydrogen sulfide production in the ageing kidney is insufficient. Exogenous H2S can partially rescue ageing-related kidney dysfunction by reducing oxidative stress, decreasing collagen deposition, and enhancing Nrf2 nuclear translocation. Recovery of endogenous hydrogen sulfide production may also contribute to the beneficial effects of NaHS treatment.

  2. Sulfide Capacity in Ladle Slag at Steelmaking Temperatures

    Science.gov (United States)

    Allertz, Carl; Sichen, Du

    2015-12-01

    Sulfide capacity measurements were conducted at 1823 K and 1873 K (1550 °C and 1600 °C) for the quaternary Al2O3-CaO-MgO-SiO2 system, for typical compositions used in the ladle in steelmaking. A copper-slag equilibrium was used under controlled oxygen and sulfur potentials. The sulfide capacity is strongly dependent on the composition and it was found to increase with the basic oxides, while it decreases with increase of the acidic components. It was found that CaO is more effective in holding sulfur in the slag compared to MgO when replacing SiO2. For the present slag compositions, Al2O3 and SiO2 behaved similar with respect to sulfur, and no considerable effect could be recorded when replacing one for the other. The sulfide capacity was also found to be strongly dependent on the temperature, increasing with temperature. The present results were compared with industrial data from the ladle, after vacuum treatment, and they were in good agreement.

  3. Selective Facet Reactivity During Cation Exchange in Cadmium Sulfide Nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Sadtler, Bryce; Demchenko, Denis; Zheng, Haimei; Hughes, Steven; Merkle, Maxwell; Dahmen, Ulrich; Wang, Lin-Wang; Alivisatos, A. Paul

    2008-12-18

    The partial transformation of ionic nanocrystals through cation exchange has been used to synthesize nanocrystal heterostructures. We demonstrate that the selectivity for cation exchange to take place at different facets of the nanocrystal plays an important role in determining the resulting morphology of the binary heterostructure. In the case of copper I (Cu+) cation exchange in cadmium sulfide (CdS) nanorods, the reaction starts preferentially at the ends of the nanorods such that copper sulfide (Cu2S) grows inwards from either end. The resulting morphology is very different from the striped pattern obtained in our previous studies of silver I (Ag+) exchange in CdS nanorods where non-selective nucleation of silver sulfide (Ag2S) occurs. From interface formation energies calculated for several models of epitaxialconnections between CdS and Cu2S or Ag2S, we infer the relative stability of each interface during the nucleation and growth of Cu2S or Ag2S within the CdS nanorods. The epitaxial connections of Cu2S to the end facets of CdS nanorods minimize the formation energy, making these interfaces stable throughout the exchange reaction. However, as the two end facets of wurtzite CdS nanorods are crystallographically nonequivalent, asymmetric heterostructures can be produced.

  4. Nanostructured Oxides and Sulfides for Thermoelectrics

    Science.gov (United States)

    Koumoto, Kunihito

    2011-03-01

    Thermoelectric power generation can be applied to various heat sources, both waste heat and renewable energy, to harvest electricity. Even though each heat source is of a small scale, it would lead to a great deal of energy saving if they are combined and collected, and it would greatly contribute to reducing carbon dioxide emission. We have been engaged in developing novel thermoelectric materials to be used for energy saving and environmental protection and are currently developing nanostructured ceramics for thermoelectric conversion. We have demonstrated a quantum confinement effect giving rise to two dimensional electron gas (2DEG) in a 2D superlattice, STO/STO:Nb (STO: strontium titanate), which could generate giant thermopower while keeping high electrical conductivity. One unit-cell thick Nb-doped well layer was estimated to show ZT=2.4 at 300K. Then, a ``synergistic nanostructuring'' concept incorporating 2DEG grain boundaries as well as nanosizing of grains has been applied to our STO material and 3D superlattice ceramics was designed and proposed. It was verified by numerical simulation that this 3D superlattice ceramics should be capable of showing ZT=1.0 at 300K which is comparable to or even higher than that of conventional bismuth telluride-based thermoelectrics. We have recently proposed titanium disulfide-based misfit-layered compounds as novel TE materials. Insertion of misfit-layers into the van der Waals gaps in layer-structured titanium disulfide thus forming a natural superlattice gives rise to internal nanointerfaces and dramatically reduces its lattice thermal conductivity. ZT value reaches 0.37 at 673 K even without optimization of electronic properties. Our challenge to further increase ZT by controlling their electronic system and superlattice structures will be presented.

  5. Compound specific isotopic fractionation patterns suggest different carbon metabolisms among Chloroflexus-like bacteria in hot spring microbial mats

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Meer, M.T.J. van der; Schouten, S.; Leeuw, J.W. de; Ward, D.M.

    2003-01-01

    Stable carbon isotope fractionations between dissolved inorganic carbon and lipid biomarkers suggest photoautotrophy by Chloroflexus-like organisms in sulfidic and nonsulfidic Yellowstone hot springs. Where co-occurring, cyanobacteria appear to cross-feed Chloroflexus-like organisms supporting photo

  6. SulfrZol(R)54硫化剂在2Mt/a加氢装置应用%Application of SulfrZol(R) 54 pre-sulfiding agent in a 2.0 MM TPY hydrogenation unit

    Institute of Scientific and Technical Information of China (English)

    王以科

    2012-01-01

    he SulfrZol? 54 pre-sulfiding agent was first tried in a 2.0 MM TPY hydrogenation unit of a petrochemical company. The commercial application results indicate that the SulfrZol? Pre-sulfiding agent can meet the pre-sulfiding requirements of hydrogenation catalysts. The decomposition temperature of SulfrZol 54 pre-sulfiding agent is lower than that of conventional pre-sulfiding agents, and the pre-sulfiding time for oxidized catalysts can be greatly shortened. In addition, the SulfrZol? 54 pre-sulfiding agent, which is low in odor, toxicity and decomposition temperature and high in flash point, offers good safety and operability. It can replace conventional pre-sulfiding agents like carbon disulfide, dimethyl disulfide, etc in pre-sulfiding of hydrogenation catalysts.%主要阐述SulfrZol(R) 54硫化剂在某炼油化工股份公司2 Mt/a加氢精制装置的首次应用.从使用效果来看,SulfrZol(R) 54硫化剂完全能满足加氢催化剂的硫化需要,并且从SulfrZol(R) 54硫化剂分解温度来看低于一般硫化剂,可以大大缩短加氢装置氧化态催化剂预硫化时间.另外,从SulfrZol(R) 54硫化剂与其它硫化剂物性分析来看,具有气味低、毒性小、分解温度低、闪点高等特点,有更好的安全性和操作性.因此,SulfrZol(R) 54硫化剂完全可以替代二硫化碳、二甲基二硫等传统硫化剂作为加氢催化剂硫化需要.

  7. Influence of sulfide concentration on the corrosion behavior of pure copper in synthetic seawater

    Science.gov (United States)

    Taniguchi, Naoki; Kawasaki, Manabu

    2008-09-01

    Corrosion rate and stress corrosion cracking (SCC) behavior of pure copper under anaerobic conditions were studied by immersion tests and slow strain rate tests (SSRT) in synthetic seawater containing Na 2S. The corrosion rate was increased with sulfide concentration both in simple saline solution and in bentnite-sand mixture. The results of SSRT showed that copper was susceptible to intergranular attack; selective dissolution at lower sulfide concentration (less than 0.005 M) and SCC at higher sulfide concentration (0.01 M). It was expected that if the sulfide concentration in groundwater is less than 0.001 M, pure copper is possible to exhibit superior corrosion resistance under anaerobic condition evident by very low corrosion rates and immunity to SCC. In such a low sulfide environment, copper overpack has the potential to achieve super-long lifetimes exceeding several tens of thousands years according to long-term simulations of corrosion based on diffusion of sulfide in buffer material.

  8. Effect of Sulfide Concentration on Copper Corrosion in Anoxic Chloride-Containing Solutions

    Science.gov (United States)

    Kong, Decheng; Dong, Chaofang; Xu, Aoni; Man, Cheng; He, Chang; Li, Xiaogang

    2017-02-01

    The structure and property of passive film on copper are strongly dependent on the sulfide concentration; based on this, a series of electrochemical methods were applied to investigate the effect of sulfide concentration on copper corrosion in anaerobic chloride-containing solutions. The cyclic voltammetry and x-ray photoelectron spectroscopy analysis demonstrated that the corrosion products formed on copper in anaerobic sulfide solutions comprise Cu2S and CuS. And the corrosion resistance of copper decreased with increasing sulfide concentration and faster sulfide addition, owing to the various structures of the passive films observed by the atomic force microscope and scanning electron microscope. A p-type semiconductor character was obtained under all experimental conditions, and the defect concentration, which had a magnitude of 1022-1023 cm-3, increased with increasing sulfide concentration, resulting in a higher rate of both film growth and dissolution.

  9. Iron sulfides in mudstones within the carbonaceous sequence of Donets Basin

    Energy Technology Data Exchange (ETDEWEB)

    Kizilshtein, L.Y.; Nastavkin, A.V. [Rostov State University, Rostov Na Donu (Russian Federation)

    2003-02-01

    The genesis of local compact segregations of iron sulfide (pyrite) in mudstones at the roof of some coal seams in the Donets Basin (Donbas) is examined. Arguments presented in the work show that sulfides were formed as a result of bacterial sulfate reduction and hydrogen sulfide generation in zones of organic matter concentration. The lack of any signs of influx of alien components testifies to in situ sulfide accumulations at the syngenetic or early diagenetic stage in bottom sediments of the basin. The shape and structure of pyrite segregations suggest that they could be 'sulfide bioherms' occasionally subjected to mechanical deformation in a liquid mud under the influence of gravitational force or external mechanical (possibly seismic) loads. The obtained data can serve as an additional source of information pertaining to the formation conditions of sulfide ore deposits.

  10. Modeling of hydrogen sulfide oxidation in concrete corrosion products from sewer pipes.

    Science.gov (United States)

    Jensen, Henriette Stokbro; Nielsen, Asbjørn Haaning; Hvitved-Jacobsen, Thorkild; Vollertsen, Jes

    2009-04-01

    Abiotic and biotic oxidation of hydrogen sulfide related to concrete corrosion was studied in corrosion products originating from a sewer manhole. The concrete corrosion products were suspended in an acidic solution, mimicking the conditions in the pore water of corroded concrete. The removal of hydrogen sulfide and dissolved oxygen was measured in parallel in the suspension, upon which the suspension was sterilized and the measurement repeated. The results revealed the biotic oxidation to be fast compared with the abiotic oxidation. The stoichiometry of the hydrogen sulfide oxidation was evaluated using the ratio between oxygen and hydrogen sulfide uptake. The ratio for the biotic oxidation pointed in the direction of elemental sulfur being formed as an intermediate in the oxidation of hydrogen sulfide to sulfuric acid. The experimental results were applied to suggest a hypothesis and a mathematical model describing the hydrogen sulfide oxidation pathway in a matrix of corroded concrete.

  11. Aerobic and anaerobic transformations of sulfide in a sewer system--field study and model simulations.

    Science.gov (United States)

    Nielsen, Asbjørn Haaning; Vollertsen, Jes; Jensen, Henriette Stokbro; Madsen, Heidi Ina; Hvitved-Jacobsen, Thorkild

    2008-01-01

    The formation and fate of sulfide in a force main and a downstream-located gravity sewer were investigated in an extensive field study. Sulfide formation in the force main was significant. However, during 14 minutes of transport in the gravity sewer, the sulfide concentration decreased 30%, on average. An application of a conceptual sewer process model for simulating the formation and fate of sulfide was demonstrated. Overall, the model predicted that approximately 90% of the decrease of the sulfide concentration in the gravity sewer was the result of sulfide oxidation and that only a small fraction entered the sewer atmosphere, causing odor and corrosion. Even so, the model predicted concrete corrosion rates of up to 1.2 mm/y in the gravity sewer section.

  12. Alkaline sulfide pretreatment of an antimonial refractory Au-Ag ore for improved cyanidation

    Science.gov (United States)

    Alp, Ibrahim; Celep, Oktay; Deveci, Haci

    2010-11-01

    This paper presents the alkaline sulfide pretreatment of an antimonial refractory gold and silver ore. In the ore, gold occurs mainly as gold-silver alloys and as associated with quartz and framboidal pyrite grains, and, to a small extent, as the inclusions within antimonial sulfides. Silver is present extensively as antimonial sulfides such as andorite. Alkaline sulfide pretreatment was shown to allow the decomposition of the antimonial sulfide minerals (up to 98% Sb removal) and to remarkably improve the amenability of gold (e.g., from silver (e.g., from leaching. An increase in reagent concentration (1-4 mol/L Na2S or NaOH) and temperature (20-80°C), and a decrease in particle size seem to produce an enhancing effect on metal extraction. These findings suggest that alkaline sulfide leaching can be suitably used as a chemical pretreatment method prior to the conventional cyanidation for antimonial refractory gold and silver ores.

  13. Biogenesis of reactive sulfur species for signaling by hydrogen sulfide oxidation pathways.

    Science.gov (United States)

    Mishanina, Tatiana V; Libiad, Marouane; Banerjee, Ruma

    2015-07-01

    The chemical species involved in H2S signaling remain elusive despite the profound and pleiotropic physiological effects elicited by this molecule. The dominant candidate mechanism for sulfide signaling is persulfidation of target proteins. However, the relatively poor reactivity of H2S toward oxidized thiols, such as disulfides, the low concentration of disulfides in the reducing milieu of the cell and the low steady-state concentration of H2S raise questions about the plausibility of persulfide formation via reaction between an oxidized thiol and a sulfide anion or a reduced thiol and oxidized hydrogen disulfide. In contrast, sulfide oxidation pathways, considered to be primarily mechanisms for disposing of excess sulfide, generate a series of reactive sulfur species, including persulfides, polysulfides and thiosulfate, that could modify target proteins. We posit that sulfide oxidation pathways mediate sulfide signaling and that sulfurtransferases ensure target specificity.

  14. Three enzymatic activities catalyze the oxidation of sulfide to thiosulfate in mammalian and invertebrate mitochondria.

    Science.gov (United States)

    Hildebrandt, Tatjana M; Grieshaber, Manfred K

    2008-07-01

    Hydrogen sulfide is a potent toxin of aerobic respiration, but also has physiological functions as a signalling molecule and as a substrate for ATP production. A mitochondrial pathway catalyzing sulfide oxidation to thiosulfate in three consecutive reactions has been identified in rat liver as well as in the body-wall tissue of the lugworm, Arenicola marina. A membrane-bound sulfide : quinone oxidoreductase converts sulfide to persulfides and transfers the electrons to the ubiquinone pool. Subsequently, a putative sulfur dioxygenase in the mitochondrial matrix oxidizes one persulfide molecule to sulfite, consuming molecular oxygen. The final reaction is catalyzed by a sulfur transferase, which adds a second persulfide from the sulfide : quinone oxidoreductase to sulfite, resulting in the final product thiosulfate. This role in sulfide oxidation is an additional physiological function of the mitochondrial sulfur transferase, rhodanese.

  15. Solubility Measurements and Modeling of Zinc, Lead and Iron Sulfides at High Temperatures and High Pressures

    DEFF Research Database (Denmark)

    Carolina Figueroa Murcia, Diana; Fosbøl, Philip Loldrup; Thomsen, Kaj

    Solubility measurements of sulfides in aqueous solutions are necessary to understand the behaviour of these scaling minerals in geothermal and oil reservoirs. The low solubility levels of Zinc Sulfide (ZnS), Lead Sulfide (PbS) and Iron Sulfide (FeS) make the solubility measurements a challenging...... task. Consequently existing data are rare and scattered. The aim of this work is to develop a reliable experimental procedure and to measure solubility of sulfides at high temperature and pressures. Additionally the experimental data are used for estimation of the solid-liquid equilibrium using...... oxygen atmosphere to avoid the risk of oxidation of sulfide minerals. The solution is kept in an equilibrium cell at constant temperature and pressure with continuous stirring. The concentration of Zn2+, Pb2+, Fe2+ and S2- are measured using Inductively Coupled Plasma Optical Emission spectrometry (ICP...

  16. Microbial control of the production of hydrogen sulfide by sulfate-reducing bacteria.

    Science.gov (United States)

    Montgomery, A D; McLnerney, M J; Sublette, K L

    1990-03-01

    A sulfide-resistant ctrain of Thiobacillus denitrificans, strain F, prevented the accumulation of sulfide by Desulfovibrio desulfuricans when both organisms were grown in liquid medium or in Berea sandstone cores. The wild-type strain of T. denitrificans did not prevent the accumulation of sulfide produced by D. desulfuricans. Strain F also prevented the accumulation of sulfide by a mixed population of sulfate-reducing bacteria enriched from an oil field brine. Fermentation balances showed that strain F stoichiometrically oxidized the sulfide produced by D. desulfuricans and the oil field brine enrichment to sulfate. These data suggest that strain F would be effective in controlling sulfide production in oil reservoirs and other environments.

  17. Metabolism of S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine to hydrogen sulfide and the role of hydrogen sulfide in S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine-induced mitochondrial toxicity.

    Science.gov (United States)

    Banki, K; Elfarra, A A; Lash, L H; Anders, M W

    1986-07-31

    The nephrotoxic cysteine S-conjugate S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine (CTFC) is metabolized by kidney homogenates and subcellular fractions to pyruvate and a reactive thiol, which is cytotoxic and partially decomposes to yield hydrogen sulfide and thiosulfate. Although hydrogen sulfide is a potent mitochondrial poison, the mitochondrial toxicity of CTFC is not attributable to hydrogen sulfide formation, as shown by different sites of inhibition of mitochondrial respiration by CTFC and hydrogen sulfide. The efficient mitochondrial oxidation of hydrogen sulfide apparently serves to protect mitochondria against the toxic effects of hydrogen sulfide generated from CTFC.

  18. Inhibition of Sulfide Mineral Oxidation by Surface Coating Agents: Batch

    Science.gov (United States)

    Choi, J.; Ji, M. K.; Yun, H. S.; Park, Y. T.; Gee, E. D.; Lee, W. R.; Jeon, B.-H.

    2012-04-01

    Mining activities and mineral industries have impacted on rapid oxidation of sulfide minerals such as pyrite (FeS2) which leads to Acid Mine Drainage (AMD) formation. Some of the abandoned mines discharge polluted water without proper environmental remediation treatments, largely because of financial constraints in treating AMD. Magnitude of the problem is considerable, especially in countries with a long history of mining. As metal sulfides become oxidized during mining activities, the aqueous environment becomes acid and rich in many metals, including iron, lead, mercury, arsenic and many others. The toxic heavy metals are responsible for the environmental deterioration of stream, groundwater and soils. Several strategies to remediate AMD contaminated sites have been proposed. Among the source inhibition and prevention technologies, microencapsulation (coating) has been considered as a promising technology. The encapsulation is based on inhibition of O2 diffusion by surface coating agent and is expected to control the oxidation of pyrite for a long time. Potential of several surface coating agents for preventing oxidation of metal sulfide minerals from both Young-Dong coal mine and Il-Gwang gold mine were examined by conducting batch experiments and field tests. Powdered pyrite as a standard sulfide mineral and rock samples from two mine outcrops were mixed with six coating agents (KH2PO4, MgO and KMnO4 as chemical agents, and apatite, cement and manganite as mineral agents) and incubated with oxidizing agents (H2O2 or NaClO). Batch experiments with Young-Dong coal mine samples showed least SO42- production in presence of KMnO4 (16% sulfate production compared to no surface coating agents) or cement (4%) within 8 days. In the case of Il-Gwang mine samples, least SO42- production was observed in presence of KH2PO4 (8%) or cement (2%) within 8 days. Field-scale pilot tests at Il-Gwang site also showed that addition of KH2PO4 decreased sulfate production from 200 to

  19. Synthesis, characterization, and reactivity of sulfided hexanuclear molybdenum cluster compounds

    Energy Technology Data Exchange (ETDEWEB)

    Spink, D.

    1990-09-21

    Hexanuclear molybdenum clusters with mixed chloride and sulfide bridging ligands were prepared by reacting {alpha}-MoCl{sub 2} with sodium hydrosulfide in the presence of sodium butoxide. The resulting species, Mo{sub 6}Cl{sub (8-x)}S{sub x}{center dot}npy(x {congruent} 3.6, n {congruent} 4, py = pyridine), was pyrophoric and insoluble. The mixed sulfide chloride cluster species Mo{sub 6}S{sub 4}Cl{sub 4}{center dot}6OPEt{sub 3} and Mo{sub 6}S{sub {approximately}5}Cl{sub {approximately}3}{center dot}6PEt{sub 3} and Mo{sub 6}S{sub 8}{center dot}6PEt{sub 3} were isolated and characterized. Phosphorus-31 nuclear magnetic resonance, electron paramagnetic resonance, and UV/visible spectra were obtained for each fraction. The completely sulfided cluster, Mo{sub 6}S{sub 8}{center dot}6PEt{sub 3}, was prepared similarly and used in various experiments as a possible precursor to Chevrel phase materials of the type Mo{sub 6}S{sub 8}or M{sub n}Mo{sub 6}S{sub 8}. With the goal of removing all of the triethylphosphine ligands, Mo{sub 6}S{sub 8}{center dot}6PEt{sub 3} was reacted with the transition metal carbonyls molybdenum hexacarbonyl and dicobalt octacarbonyl. Reaction on the molecular sulfide cluster with copper(I) chloride in toluene gave a completely insoluble product. The reaction of Mo{sub 6}S{sub 8}{center dot}6PEt{sub 3} with propylene sulfide gave a product whose infrared spectra showed only very weak peaks associated with coordinated triethylphosphine. The elemental analysis of this product fit the formula Mo{sub 6}S{sub 8}{center dot}5SPEt{sub 3}. Reactivity of the outer ligands of the Mo{sub 6}S{sub 8}{center dot}npy and Mo{sub 6}S{sub 8}{center dot}(6{minus}x)PrNH{sub x} clusters were investigated. Crystalline Mo{sub 6}S{sub 8}{center dot}6THT was recovered from the reaction of the n-propylamine derivative with THT. A crystal structure determination was done. 87 refs., 12 fig., 15 tabs.

  20. Research of the Plasma Sulfide Layer Formed on the Nitrocarburizing Layer

    Institute of Scientific and Technical Information of China (English)

    LI Xin; MA Shi-ning; HU Chun-hua; QIU Ji; HUANG Yuan-lin

    2004-01-01

    Low-temperature sulfurizing after nitrocarburizing are compared with only low-temperature sulfurizing on the surface of CrMoCu alloyed cast iron, the surface morphologies and microstructures are investigated by SEM and EDS.Results show that under proper treatment parameters, there are sulfide layer on both of the surfaces, and can more easily obtain sulfide layers on the surface of nitrocarburizing. Forming mechanism of sulfides were also studied elementarily.

  1. The impact of electrogenic sulfide oxidation on elemental cycling and solute fluxes in coastal sediment

    OpenAIRE

    Rao, A.M.F.; Malkin, S.Y.; Hidalgo-Martinez, S.; Meysman, Filip

    2016-01-01

    Filamentous sulfide oxidizing cable bacteria are capable of linking the oxidation of free sulfide in deep anoxic layers of marine sediments to the reduction of oxygen or nitrate in surface sediments by conducting electrons over centimeter-scale distances. Previous studies have shown that this newly discovered microbial process, referred to as electrogenic sulfide oxidation (e-SOx), may alter elemental cycling in sediments, but the nature and rates of the resulting biogeochemical transformatio...

  2. High Temperature Corrosion of Fe-C-S Cast Irons in Oxidizing and Sulfidizing Atmospheres

    Institute of Scientific and Technical Information of China (English)

    Thuan-Dinh NGUYEN; Dong-Bok LEE

    2008-01-01

    The corrosion behavior of spheroidal graphite and flake graphite cast irons was studied in oxidizing and sulfidizing atmospheres between 600 and 800℃ for 50 h. The corrosion rate in the sulfidizing atmosphere was faster than that in air above 700℃, due to the formation of the Feo.975S sulfide. The corrosion rate of the spheroidal graphite cast iron was similar to that of the flake graphite cast iron.

  3. Regarding "Sulfide Capacity in Ladle Slag at Steelmaking Temperatures," C. Allertz, Du Sichen; MMTB 2015 December

    Science.gov (United States)

    Pelton, Arthur; Kang, Youn-Bae

    2016-09-01

    Allertz and Sichen measured sulfide contents of slags in equilibrium with Cu-S solutions. Results are in very good agreement with calculations by FactSage whose databases were developed by modeling other sets of data obtained under different conditions. However, when results are reported as sulfide capacities, significant errors may result if these are used to calculate sulfide contents at oxygen and sulfur potentials which differ from those of the experiments and/or are fixed by different means.

  4. Spectral induced polarization and electrodic potential monitoring of microbially mediated iron sulfide transformations

    Energy Technology Data Exchange (ETDEWEB)

    Hubbard, Susan; Personna, Y.R.; Ntarlagiannis, D.; Slater, L.; Yee, N.; O' Brien, M.; Hubbard, S.

    2008-02-15

    Stimulated sulfate-reduction is a bioremediation technique utilized for the sequestration of heavy metals in the subsurface.We performed laboratory column experiments to investigate the geoelectrical response of iron sulfide transformations by Desulfo vibriovulgaris. Two geoelectrical methods, (1) spectral induced polarization (SIP), and (2) electrodic potential measurements, were investigated. Aqueous geochemistry (sulfate, lactate, sulfide, and acetate), observations of precipitates (identified from electron microscopy as iron sulfide), and electrodic potentials on bisulfide ion (HS) sensitive silver-silver chloride (Ag-AgCl) electrodes (630 mV) were diagnostic of induced transitions between an aerobic iron sulfide forming conditions and aerobic conditions promoting iron sulfide dissolution. The SIP data showed 10m rad anomalies during iron sulfide mineralization accompanying microbial activity under an anaerobic transition. These anomalies disappeared during iron sulfide dissolution under the subsequent aerobic transition. SIP model parameters based on a Cole-Cole relaxation model of the polarization at the mineral-fluid interface were converted to (1) estimated biomineral surface area to pore volume (Sp), and (2) an equivalent polarizable sphere diameter (d) controlling the relaxation time. The temporal variation in these model parameters is consistent with filling and emptying of pores by iron sulfide biofilms, as the system transitions between anaerobic (pore filling) and aerobic (pore emptying) conditions. The results suggest that combined SIP and electrodic potential measurements might be used to monitor spatiotemporal variability in microbial iron sulfide transformations in the field.

  5. Sulfur speciation and sulfide oxidation in the water column of the Black Sea

    Science.gov (United States)

    Luther, George W., III; Church, Thomas M.; Powell, David

    We have applied sulfur speciation techniques to understand the chemistry and cycling of sulfur in Black Sea waters. The only reduced dissolved inorganic sulfur species detected (above the low minimum detection limits of the voltammetric methods employed) in the water column was hydrogen sulfide. The maximum concentration of sulfide (423 μM) is similar to previous reports. Using a cathodic stripping square wave voltammetry (CSSWV) method for nanomolar levels of sulfide, we determined the precise boundary between the "free" hydrogen sulfide (sulfidic) zone and the upper (oxic/suboxic) water column at the two stations studied. This boundary has apparently moved up by about 50 m in the past 20 years. Our results help demonstrate three chemically distinct zones of water in the central basin of the Black Sea: (1) the oxic [0-65 m], (2) the anoxic/nonsulfidic [65-100 m] and (3) the sulfidic [>100 m]. Sulfide bound to metals ("complexed" sulfide) is observed in both the oxic and anoxic/nonsulfidic zones of the water column. This supports previous studies on metal sulfide forms. From the electrochemical data, it is possible to estimate the strength of the complexation of sulfide to metals (log K = 10 to 11). Thiosulfate and sulfite were below our minimum detectable limit (MDL) of 50 nM using CSSWV. Elemental sulfur (MDL 5 nM) was detected below the onset of the hydrogen sulfide zone (90-100 m) with a maximum of 30-60 nM near 120 m. The sulfur speciation results for the Black Sea are lower by one order of magnitude or more than other marine systems such as the Cariaco Trench and salt marshes. New HPLC techniques were applied to detect thiols at submicromolar levels. The presence of thiols (2-mercaptoethylamine, 2-mercaptoethanol, N-acetylcysteine and glutathione) is correlated with the remineralization of organic matter at the oxic and anoxic/nonsulfidic interface. Water samples collected from the upper 50 m of the sulfidic zone showed significant sulfide oxidation on

  6. Sulfides in diamonds and in xenoliths from kimberlite pipes of Yakutiia

    Science.gov (United States)

    Bulanova, Galina P.; Spetsius, Zdislav V.; Leskova, Nelli V.

    The characteristics of sulfides from diamonds and xenoliths are compared using literature data on the mineralogy of sulfides in diamonds and in deep-seated xenoliths from kimberlite pipes. Results are presented on the Fe-Ni-Cu-Co-S mineral systems of mantle associations, sulfide inclusions in diamonds and megacrystals of kimberlite rocks, and minerals of the Fe-Ni-Cu-Co-S system in mantle xenoliths from kimberlite pipes. Particular consideration is given to the nature of sulfide mineralization in mantle xenoliths and diamonds.

  7. Corrosion of concrete sewers--the kinetics of hydrogen sulfide oxidation.

    Science.gov (United States)

    Vollertsen, Jes; Nielsen, Asbjørn Haaning; Jensen, Henriette Stokbro; Wium-Andersen, Tove; Hvitved-Jacobsen, Thorkild

    2008-05-01

    Hydrogen sulfide absorption and oxidation by corroding concrete surfaces was quantified in a test rig consisting of 6 concrete pipes operated under sewer conditions. The test rig was placed in an underground sewer monitoring station with access to fresh wastewater. Hydrogen sulfide gas was injected into the pipe every 2nd hour to peak concentrations around 1000 ppm. After some months of operation, the hydrogen sulfide became rapidly oxidized by the corroding concrete surfaces. At hydrogen sulfide concentrations of 1000 ppm, oxidation rates as high as 1 mg S m(-2) s(-1) were observed. The oxidation process followed simple nth order kinetics with a process order of 0.45-0.75. Extrapolating the results to gravity sewer systems showed that hydrogen sulfide oxidation by corroding concrete is a fast process compared to the release of hydrogen sulfide from the bulk water, resulting in low gas concentrations compared with equilibrium. Balancing hydrogen sulfide release with hydrogen sulfide oxidation at steady state conditions demonstrated that significant corrosion rates--several millimeters of concrete per year--can potentially occur at hydrogen sulfide gas phase concentrations well below 5-10 ppm. The results obtained in the study advances the knowledge on prediction of sewer concrete corrosion and the extent of odor problems.

  8. Mapping hydrogen sulfide in rats with a novel azo-based fluorescent probe.

    Science.gov (United States)

    Li, Xin; Cheng, Juan; Gong, Yanling; Yang, Bo; Hu, Yongzhou

    2015-03-15

    We report herein a reaction-based fluorescent switch-on sulfide sensor, azo3, for the quantification of endogenous sulfides in rat tissues. The sensor was exploited based on the novel azo-sulfide chemistry and designed by locking the rhodol fluorophore into its nonfluorescent form with an azo group. However, the azo group would undergo a specific and biocompatible reaction with sulfides, triggering significant fluorescence increasements which were linear to the concentrations of sulfides. Azo3 distinguished by its high sensitivity (148-fold fluorescent switch-on response), good selectivity (22-fold more selective towards sulfides than other bio-thiol species) and low detection limit (500nM). Moreover, the azo3-based assay for biological sulfides displayed the unique advantage of being insusceptible to ultraviolet (UV) irradiation. Azo3 has been successfully applied to the quantification of endogenous sulfides in rat plasma and tissues including heart, brain, liver, spleen, lung and kidney. In addition to providing azo3 as a valuable tool to analyze sulfides in biological samples, we also discussed the influences of the electron effect on the sensitivity of the probes, which would shed some light on the design of future reaction-based probes.

  9. Formation of Iron Sulfide in Water-Body Sediment and Its Influence on Environment

    Institute of Scientific and Technical Information of China (English)

    YAN Lei; SUMI Katsuhiro

    2008-01-01

    Iron sulfide is an important reductive pollutant in aquatic sediment, so that increasing attentions have been paid to it in recent years. In this paper, the formation of iron sulfide in water-body sediment was introduced. Moreover, its adverse influences upon environment were summarized, including direct contribution to deficiency of dissolved oxygen in water, association with eutrophication in water-bodies and impact on geochemical sulfur cycle. Since conventional chemical analysis for iron sulfide has several disadvantages, new technique for rapid determination of iron sulfide on-line was prospected.

  10. Microbial oxidation of soluble sulfide in produced water from the Bakkeen Sands

    Energy Technology Data Exchange (ETDEWEB)

    Gevertz, D.; Zimmerman, S. [Agouron Institute, La Jolla, CA (United States); Jenneman, G.E. [Phillips Petroleum Company, Bartlesville, OK (United States)] [and others

    1995-12-31

    The presence of soluble sulfide in produced water results in problems for the petroleum industry due to its toxicity, odor, corrosive nature, and potential for wellbore plugging. Sulfide oxidation by indigenous nitrate-reducing bacteria (NRB) present in brine collected from wells at the Coleville Unit (CVU) in Saskatchewan, Canada, was investigated. Sulfide oxidation took place readily when nitrate and phosphate were added to brine enrichment cultures, resulting in a decrease in sulfide levels of 99-165 ppm to nondetectable levels (< 3.3 ppm). Produced water collected from a number of producing wells was screened to determine the time required for complete sulfide oxidation, in order to select candidate wells for treatment. Three wells were chosen, based on sulfide removal in 48 hours or less. These wells were treated down the backside of the annulus with a solution containing 10 mM KNO{sub 3} and 100 {mu}M NaH{sub 2}PO{sub 4}. Following a 24- to 72-hour shut-in, reductions in pretreatment sulfide levels of greater than 90% were observed for two of the wells, as well as sustained sulfide reductions of 50% for at least two days following startup. NRB populations in the produced brine were observed to increase significantly following treatment, but no significant increases in sulfate-reducing bacteria were observed. These results demonstrate the technical feasibility of stimulating indigenous populations of NRB to remediate and control sulfide in produced brine.

  11. Biological and chemical sulfide oxidation in a Beggiatoa inhabited marine sediment

    DEFF Research Database (Denmark)

    Preisler, André; de Beer, Dirk; Lichtschlag, Anna;

    2007-01-01

    gradient and corresponding high sulfide flux, a typical characteristic of Beggiatoa habitats, is not needed for their metabolic performance, but rather used as a chemotactic cue by the highly motile filaments to avoid getting lost at depth in the sediment. Indeed sulfide is a repellant for Beggiatoa...... and corresponding high sulfide flux, a typical characteristic of Beggiatoa habitats, is not needed for their metabolic performance, but rather used as a chemotactic cue by the highly motile filaments to avoid getting lost at depth in the sediment. Indeed sulfide is a repellant for Beggiatoa...

  12. Spectral induced polarization and electrodic potential monitoring of microbially mediated iron sulfide transformations

    Science.gov (United States)

    Personna, Yves Robert; Ntarlagiannis, Dimitrios; Slater, Lee; Yee, Nathan; O'Brien, Michael; Hubbard, Susan

    2008-06-01

    Stimulated sulfate-reduction is a bioremediation technique utilized for the sequestration of heavy metals in the subsurface. We performed laboratory column experiments to investigate the geoelectrical response of iron sulfide transformations by Desulfovibrio vulgaris. Two geoelectrical methods, (1) spectral induced polarization (SIP), and (2) electrodic potential measurements, were investigated. Aqueous geochemistry (sulfate, lactate, sulfide, and acetate), observations of precipitates (identified from electron microscopy as iron sulfide), and electrodic potentials on bisulfide ion (HS-) sensitive silver-silver chloride (Ag-AgCl) electrodes (˜-630 mV) were diagnostic of induced transitions between anaerobic iron sulfide forming conditions and aerobic conditions promoting iron sulfide dissolution. The SIP data showed ˜10 mrad anomalies during iron sulfide mineralization accompanying microbial activity under an anaerobic transition. These anomalies disappeared during iron sulfide dissolution under the subsequent aerobic transition. SIP model parameters based on a Cole-Cole relaxation model of the polarization at the mineral-fluid interface were converted to (1) estimated biomineral surface area to pore volume (Sp), and (2) an equivalent polarizable sphere diameter (d) controlling the relaxation time. The temporal variation in these model parameters is consistent with filling and emptying of pores by iron sulfide biofilms, as the system transitions between anaerobic (pore filling) and aerobic (pore emptying) conditions. The results suggest that combined SIP and electrodic potential measurements might be used to monitor spatiotemporal variability in microbial iron sulfide transformations in the field.

  13. XAFS characterization of industrial catalysts: in situ study of phase transformation of nickel sulfide

    Science.gov (United States)

    Wang, J.; Jia, Z.; Wang, Q.; Zhao, S.; Xu, Z.; Yang, W.; Frenkel, A. I.

    2016-05-01

    The online sulfiding process for nickel-contained catalyst often ends up with a nickel sulfide mixture in refinery plant. To elucidate the local environment of nickel and its corresponding sulfur species, a model catalyst (nickel sulfide) and model thermal process were employed to explore the possibilities for characterization of real catalysts in industrial conditions. The present investigation shows effectiveness of in situ XANES and EXAFS measurements for studying the phase stability and phase composition in these systems, which could be used to simulate real sulfiding process in industrial reactions, such as hydrodesulfurizations of oil.

  14. Pd-NHC-Catalyzed Alkynylation of General Aryl Sulfides with Alkynyl Grignard Reagents.

    Science.gov (United States)

    Baralle, Alexandre; Yorimitsu, Hideki; Osuka, Atsuhiro

    2016-07-25

    Cross-coupling reactions of unactivated aryl sulfides with alkynylmagnesium chloride have been invented to afford 1-aryl-1-alkynes with the aid of a palladium/N-heterocyclic carbene complex. This reaction has by far the widest scope of all transformations utilizing aryl sulfides and alkynes, while known cross-coupling alkynylations of aryl-sulfur electrophiles require activated azaaryl sulfides, thiolactams, or arenesulfonyl chlorides. The alkynylation of aryl sulfides is compatible with typical protecting functional groups. The alkynylation is applied to the synthesis of benzofuran-based fluorescent molecules by taking advantage of characteristic organosulfur chemistry.

  15. Sulfide intrusion in the tropical seagrasses Thalassia testudinum and Syringodium filiforme

    DEFF Research Database (Denmark)

    Holmer, Marianne; Pedersen, Ole; Krause-Jensen, Dorte;

    2009-01-01

    and on proximity to anthropogenic nutrient sources. Meadow characteristics (shoot density, above- and below-ground biomass, nutrient content) were sampled along with sediment biogeochemistry. Sulfide intrusion was high in T. testudinum, as up to 96% of total sulfur in the plant was derived from sediment......-derived sulfides. The sulfide intrusion was negatively correlated to the turnover of sulfides in the sediments regulated by both plant parameters and sediment sulfur pools. Sediment iron content played an indirect role by affecting sulfide turnover rates. Leaf production was negatively correlated with sulfide...

  16. Eddy covariance carbonyl sulfide flux measurements with a quantum cascade laser absorption spectrometer

    Science.gov (United States)

    Gerdel, Katharina; Spielmann, Felix M.; Hammerle, Albin; Wohlfahrt, Georg

    2016-04-01

    Carbonyl sulfide (COS) is the most abundant sulfur containing trace gas present in the troposphere at concentrations of around 500 ppt. Recent interest in COS by the ecosystem-physiological community has been sparked by the fact that COS co-diffuses into plant leaves pretty much the same way as carbon dioxide (CO2) does, but in contrast to CO2, COS is not known to be emitted by plants. Thus uptake of COS by vegetation has the potential to be used as a tracer for canopy gross photosynthesis, which cannot be measured directly, however represents a key term in the global carbon cycle. Since a few years, quantum cascade laser absorption spectrometers (QCLAS) are commercially available with the precision, sensitivity and time response suitable for eddy covariance (EC) flux measurements. While there exist a handful of published reports on EC flux measurements in the recent literature, no rigorous investigation of the applicability of QCLAS for EC COS flux measurements has been carried out so far, nor have been EC processing and QA/QC steps developed for carbon dioxide and water vapor flux measurements within FLUXNET been assessed for COS. The aim of this study is to close this knowledge gap, to discuss critical steps in the post-processing chain of COS EC flux measurements and to devise best-practice guidelines for COS EC flux data processing. To this end we collected EC COS (and CO2, H2O and CO) flux measurements above a temperate mountain grassland in Austria over the vegetation period 2015 with a commercially available QCLAS. We discuss various aspects of EC data post-processing, in particular issues with the time-lag estimation between sonic anemometer and QCLAS signals and QCLAS time series detrending, as well as QA/QC, in particular flux detection limits, random flux uncertainty, the interaction of various processing steps with common EC QA/QC filters (e.g. detrending and stationarity tests), u*-filtering, etc.

  17. Origin and Distribution of Hydrogen Sulfide in Oil-Bearing Basins, China

    Institute of Scientific and Technical Information of China (English)

    ZHU Guangyou; ZHANG Shuichang; LIANG Yingbo

    2009-01-01

    The concentration of hydrogen sulfide gas (H_2S) varies greatly in the oil-bearing basins of China, from zero to 90%. At present, oil and gas reservoirs with high H_2S concentration have been discovered in three basins, viz. the Bohai Bay Basin, Sichuan Basin and the Tarim Basin, whereas natural gas with low H_2S concentration has been found in the Ordos Basin, the Songiiao Basin and the Junggar Basin. Studies suggest that in China H_2S origin types are very complex. In the carbonate reservoir of the Sichuan Basin, the Ordos Basin and the Tarim Basin, as well as the carbonate-dominated reservoir in the Luojia area of the Jiyang depression in the Bohai Bay Basin, Wumaying areas of the Huanghua depression, and Zhaolanzhuang areas of the Jizhong depression, the H_2S is of Thermochemical Sulfate Reduction (TSR) origin. The H_2S is of Bacterial Sulphate Reduction (BSR) origin deduced from the waterflooding operation in the Changheng Oiifieid (placanticline oil fields) in the Songliao Basin. H_2S originates from thermal decomposition of sulfur-bearing crude oil in the heavy oil area in the Junggar Basin and in the Liaohe heavy oil steam pilot area in the western depression of the Bohai Bay Basin. The origin types are most complex, including TSR and thermal decomposition of sulfcompounds among other combinations of causes. Various methods have been tried to identify the origin mechanism and to predict the distribution of H_2S. The origin identification methods for H_2S mainly comprise sulfur and carbon isotopes, reservoir petrology, particular biomarkers, and petroleum geology integrated technologies; using a combination of these applications can allow the accurate identification of the origins of H_2S. The prediction technologies for primary and secondary origin of H_2S have been set up separately.

  18. Do oceanic emissions account for the missing source of atmospheric carbonyl sulfide?

    Science.gov (United States)

    Lennartz, Sinikka; Marandino, Christa A.; von Hobe, Marc; Cortés, Pau; Simó, Rafel; Booge, Dennis; Quack, Birgit; Röttgers, Rüdiger; Ksionzek, Kerstin; Koch, Boris P.; Bracher, Astrid; Krüger, Kirstin

    2016-04-01

    Carbonyl sulfide (OCS) has a large potential to constrain terrestrial gross primary production (GPP), one of the largest carbon fluxes in the carbon cycle, as it is taken up by plants in a similar way as CO2. To estimate GPP in a global approach, the magnitude and seasonality of sources and sinks of atmospheric OCS have to be well understood, to distinguish between seasonal variation caused by vegetation uptake and other sources or sinks. However, the atmospheric budget is currently highly uncertain, and especially the oceanic source strength is debated. Recent studies suggest that a missing source of several hundreds of Gg sulfur per year is located in the tropical ocean by a top-down approach. Here, we present highly-resolved OCS measurements from two cruises to the tropical Pacific and Indian Ocean as a bottom-up approach. The results from these cruises show that opposite to the assumed ocean source, direct emissions of OCS from the tropical ocean are unlikely to account for the missing source. To reduce uncertainty in the global oceanic emission estimate, our understanding of the production and consumption processes of OCS and its precursors, dimethylsulfide (DMS) and carbon disulphide (CS2), needs improvement. Therefore, we investigate the influence of dissolved organic matter (DOM) on the photochemical production of OCS in seawater by considering analysis of the composition of DOM from the two cruises. Additionally, we discuss the potential of oceanic emissions of DMS and CS2 to closing the atmospheric OCS budget. Especially the production and consumption processes of CS2 in the surface ocean are not well known, thus we evaluate possible photochemical or biological sources by analyzing its covariation of biological and photochemical parameters.

  19. Soil carbonyl sulfide fluxes in a Mediterranean ecosystem: insights from model-data fusion analysis

    Science.gov (United States)

    Sun, W.; Seibt, U. H.; Maseyk, K. S.; Lett, C.

    2013-12-01

    Carbonyl sulfide (COS) is linked to biosphere components of the carbon cycle, due in large part to its hydrolysis by the enzyme carbonic anhydrase (CA). Stomatal diffusion models and observations at leaf and ecosystem scales have demonstrated the potential of COS as a tracer for Gross Primary Production (GPP). Although considered small relative to canopy COS fluxes, accurate knowledge of soil COS fluxes is required for the use of net ecosystem COS fluxes in carbon flux partitioning. However, extensive field measurements of soil COS fluxes are rare and process-based modeling is limited. Here we report continuous chamber measurements of soil COS fluxes in a Mediterranean ecosystem in the Santa Monica Mountains, California during April and early May 2013. Both COS uptake and emissions were observed, but the soil acted as a net sink in most conditions and was a net source only when soil temperatures were above 22 C. COS sink fluxes were positively correlated with soil water content and CO2 fluxes. COS uptake had a maximum at a temperature around 15 C. However, no single environmental variable could be correlated to COS fluxes with an r-square > 0.6. COS fluxes from soil chambers ranged from -9 to 2.5 pmol m-2 s-1. Leaf litter appeared to increase soil COS metabolic activity. We observed huge bursts of soil COS uptake induced by a precipitation event, probably due to enhanced soil microbial activity resulting from alleviated water limitation and a decrease in soil temperature towards the optimum. We used a soil gas exchange model coupled with CA enzyme kinetics to simulate the soil COS fluxes. Micrometeorological and soil data were used to drive the soil flux model. Model simulations indicated that diurnal and synoptic variations of COS fluxes were driven by soil temperature and water content, controlling both CA activity and diffusion. We suggest that multiple parameters need to be optimized to reduce uncertainties in models of soil COS fluxes at larger scales.

  20. Changes of Cu, Zn, and Ni chemical speciation in sewage sludge co-composted with sodium sulfide and lime

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A batch composting study was performed to evaluate the feasibility of co-composting sewage sludge with sodium sulfide and lime (SSL) mixture (Na2S/CaO= 1:1), aiming at reducing the availability of heavy metals in the sludge compost. Sewage sludge with sawdust as a bulking agent was amended with SSL at 3% (w/w, dw), and composted for 15 d in laboratory batch reactors. The four stages of the Tessier sequential extraction method was employed to investigate changes in heavy metal fractions of Cu, Zn, and Ni in sewage sludge composted with SSL. For all the three metals, the mobile fractions, such as, exchangeable and carbonate bound were mainly transformed into low availability fractions (organic matter and sulfide, Fe-Mn oxides bound and residual forms), and the addition of SSL enhanced this transformation. Therefore, SSL is a suitable material to co-compost with sewage sludge to reduce the availability of heavy metals. According to the cabbage seed germination test, a SSL amendment of ≤3% (w/w, dw) is recommended to co-compost with sewage sludge.