Mesostructured metal germanium sulfides

Energy Technology Data Exchange (ETDEWEB)

MacLachlan, M.J.; Coombs, N.; Bedard, R.L.; White, S.; Thompson, L.K.; Ozin, G.A.

1999-12-29

A new class of mesostructured metal germanium sulfide materials has been prepared and characterized. The synthesis, via supramolecular assembly of well-defined germanium sulfide anionic cluster precursors and transition-metal cations in formamide, represents a new strategy for the formation of this class of solids. A variety of techniques were employed to examine the structure and composition of the materials. Structurally, the material is best described as a periodic mesostructured metal sulfide-based coordination framework akin to periodic hexagonal mesoporous silica, MCM-41. At the molecular scale, the materials strongly resemble microstructured metal germanium sulfides, in which the structure of the [Ge{sub 4}S{sub 10}]{sup 4{minus}} cluster building-blocks are intact and linked via {mu}-S-M-S bonds. Evidence for a metal-metal bond in mesostructured Cu/Ge{sub 4}S{sub 10} is also provided.

Enhanced reactive adsorption of hydrogen sulfide on the composites of graphene/graphite oxide with copper (hydr)oxychlorides.

Science.gov (United States)

Mabayoje, Oluwaniyi; Seredych, Mykola; Bandosz, Teresa J

2012-06-27

Composites of copper (hydr)oxychlorides with graphite oxide or graphene were synthesized and used as adsorbents of hydrogen sulfide at dynamic conditions at ambient temperatures. The materials were extensively characterized before and after adsorption in order to link their performance to the surface features. X-ray diffraction, FTIR, thermal analysis, TEM, SEM/EDX, and adsorption of nitrogen were used. It was found that the composite with graphene has the most favorable surface features enhancing reactive adsorption of hydrogen sulfide. The presence of moisture in the H2S stream has a positive effect on the removal process owing to the dissociation process. H2S is retained on the surface via a direct replacement of OH groups and via acid-base reactions with the copper (hydr)oxide. Highly dispersed reduced copper species on the surface of the composite with graphene enhance activation of oxygen and cause formation of sulfites and sulfates. Higher conductivity of the graphene phase than that of graphite oxide helps in electron transfer in redox reactions.

The use of ERTS-1 images in the search for large sulfide deposits in the Chagai District, Pakistan

Science.gov (United States)

Schmidt, R. G. (Principal Investigator)

1974-01-01

The author has identified the following significant results. Visual examination of color composites was tested under relatively ideal conditions for direct detection of large hydrothermal sulfide deposits at the low-grade porphyry copper deposit at Saindak, western Chagai District, Pakistan. The Saindak deposit is characterized by an elongate zone of easily eroded sulfide-rich rock surrounded by a resistant rim of hornfels and propylitically altered rock. The geomorphic features related to the Saindak deposit are easily distinguished on ERTS-1 images. Attempts to detect a color anomaly using false-color composites were not successful. About 36,000 square km of the western Chagai District were examined on false-color composites for direct evidence of large sulfide deposits. New geologic information acquired from the images was used in conjunction with the known geology to evaluate two previously known proposed areas and to suggest seven additional targets for field checking, one of which is proposed on the basis of tonal anomaly alone. The study also showed that Saindak-type deposits are not likely to be present in some extensive areas of the Chagai District; and also that a rim like that at Saindak does not form if regional metamorphism has increased the resistance of the country rock to erosion.

Experimental simulations of sulfide formation in the solar nebula.

Science.gov (United States)

Lauretta, D S; Lodders, K; Fegley, B

1997-07-18

Sulfurization of meteoritic metal in H2S-H2 gas produced three different sulfides: monosulfide solid solution [(Fe,Ni)1-xS], pentlandite [(Fe,Ni)9-xS8], and a phosphorus-rich sulfide. The composition of the remnant metal was unchanged. These results are contrary to theoretical predictions that sulfide formation in the solar nebula produced troilite (FeS) and enriched the remaining metal in nickel. The experimental sulfides are chemically and morphologically similar to sulfide grains in the matrix of the Alais (class CI) carbonaceous chondrite, suggesting that these meteoritic sulfides may be condensates from the solar nebula.

Iron sulfide (troilite) inclusion extracted from Sikhote-Alin iron meteorite: Composition, structure and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Oshtrakh, M.I., E-mail: oshtrakh@gmail.com [Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation); Department of Experimental Physics, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation); Klencsár, Z. [Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest, 1117 (Hungary); Petrova, E.V.; Grokhovsky, V.I. [Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation); Chukin, A.V. [Department of Theoretical Physics and Applied Mathematics, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation); Shtoltz, A.K. [Department of Electrophysics, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation); Maksimova, A.A. [Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation); Felner, I. [Racah Institute of Physics, The Hebrew University, Jerusalem (Israel); Kuzmann, E.; Homonnay, Z. [Institute of Chemistry, Eötvös Loránd University, Budapest (Hungary); Semionkin, V.A. [Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation); Department of Experimental Physics, Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002 (Russian Federation)

2016-05-01

Iron sulfide (troilite) inclusion extracted from Sikhote-Alin IIAB iron meteorite was examined for its composition, structure and magnetic properties by means of several complementary analytical techniques such as: powder X-ray diffractometry, scanning electron microscopy combined with energy-dispersive X-ray spectroscopy, magnetization measurements, ferromagnetic resonance spectroscopy and {sup 57}Fe Mössbauer spectroscopy with a high velocity resolution. The applied techniques consistently indicated the presence of daubréelite (FeCr{sub 2}S{sub 4}) as a minority phase beside troilite proper (FeS). As revealed by {sup 57}Fe Mössbauer spectroscopy, the Fe atoms in troilite were in different microenvironments associated with either the ideal FeS structure or that of a slightly iron deficient Fe{sub 1–x}S. Phase transitions of troilite were detected above room temperature by ferromagnetic resonance spectroscopy. A novel analysis of 295 and 90 K {sup 57}Fe Mössbauer spectra was carried out and the hyperfine parameters associated with the ideal structure of troilite were determined by considering the orientation of the hyperfine magnetic field in the eigensystem of the electric field gradient at the {sup 57}Fe nucleus. - Highlights: • The presence of daubréelite in iron sulfide inclusion in Sikhote-Alin iron meteorite. • The presence of the ideal FeS and iron deficient Fe{sub 1–x}S in iron sulfide inclusion. • New way of the iron sulfide Mössbauer spectrum approximation.

Determination of sulfur isotopic composition for the study of iron sulfides origin, biotic or abiotic, in anoxic corrosion

International Nuclear Information System (INIS)

Grousset, Sophie

2016-01-01

The first goal of this project was to develop a methodology based on the study of the sulfur isotopic composition enabling the determination of iron sulfides origin, biotic or abiotic, within the corrosion products layers (CPL). Then, the aim was to apply this methodology to real corrosion systems in order to determine the mechanisms of iron sulfides formation. Sulfur isotopic analyses methodologies, adapted to micrometric iron sulfides layers observed in real corrosion systems, were developed in nanoSIMS and ToF-SIMS. The study of iron sulfides formed in anoxic carbonated medium with or without sulphate-reducing bacteria validated the use of these methods for the determination of iron sulfides origin. The application of these methods coupled with the precise characterization of irons sulfides formed in the real corrosion systems show two kind of corrosion pattern. In pattern 1, the iron sulfides are localized in the external part of the CPL. They result from the Fe 2+ migration from the metal surface to areas rich in biotic S 2- . In this pattern, corrosion rates are lower than 20 μm/year for laboratory systems, and lower than 5 μm/year for archaeological objects. In pattern 2, the large presence of conductive phases in the CPL results in the delocalization of electrons, and so a disequilibrium of the charges at the metal's surface. That leads to the migration of biotic S 2- in the CPL till the metal where they precipitate in iron sulphides. This pattern shows high corrosion rates (∼100 μm/an) that might be resulting from the accumulation of bio-corrosion and chloride corrosion mechanisms. (author) [fr

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......: (1) impact of low viscous droplets of iron sulfide; and (2) sulfur diffusion. Previous research on the influence of pyrite on slagging focused on the decomposition of pyrite into pyrrhotite and especially on the oxidation stage of this product during impact on the heat transfer surfaces...

Characteristics of diffusion zone in changing glass-metal composite processing conditions

Science.gov (United States)

Lyubimova, O. N.; Morkovin, A. V.; Andreev, V. V.

2018-03-01

The influence of manufacturing technology on the characteristics of the glass and steel contact zone in manufacturing new structural material - glass-metal composite is studied theoretically and experimentally. Different types of structures in the contact zone and its dimensions affect the strength characteristics of the composite. Knowledge about changing the width of the glass and steel contact zone after changing such parameters of the technological regime as temperature, holding time and use of solders will allow one to control the structure and characteristics of the glass-metal composite. Experimental measurements of the width of the diffusion zone in the glass-metal composite for different regimes and their statistical processing according to the full factor experiment are presented in this article. The results of analysis of some mechanical characteristics of the diffusion zone are presented: microhardness and modulus of elasticity for samples, prepared according to different processing regimes.

Carbon nanotubes/cobalt sulfide composites as potential high-rate and high-efficiency supercapacitors

Science.gov (United States)

Chen, Chia-Ying; Shih, Zih-Yu; Yang, Zusing; Chang, Huan-Tsung

2012-10-01

We have prepared carbon nanotube (CNT)/cobalt sulfide (CoS) composites from cobalt nitrate, thioacetamide, and CNTs in the presence of poly(vinylpyrrolidone). CNT/CoS composites are deposited onto fluorine-doped tin oxide glass substrates and then subjected to simple annealing at 300 °C for 0.5 h to fabricate CNT/CoS electrodes. Data collected from Raman spectroscopy, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and d-spacing reveal the changes in the CoS structures and crystalline lattices after annealing. Cyclic voltammetry results reveal that the annealed CNT/CoS composite electrodes yield values of 2140 ± 90 and 1370 ± 50 F g-1 for specific capacitance at scan rates of 10 and 100 mV s-1, respectively. To the best of our knowledge, the annealed CNT/CoS composite electrodes provide higher specific capacitance relative to other reported ones at a scan rate of 100 mV s-1. CNT/CoS composite electrodes yield a power density of 62.4 kW kg-1 at a constant discharge current density of 217.4 A g-1. With such a high-rate capacity and power density, CNT/CoS composite supercapacitors demonstrate great potential as efficient energy storage devices.

Paleohydrogeological implications from fracture calcites and sulfides in a major hydrogeological zone HZ19 at Olkiluoto

International Nuclear Information System (INIS)

Sahlstedt, E.; Karhu, J.; Rinne, K.

2009-08-01

30 samples of fracture mineral fillings in or near water conducting fractures at Olkiluoto were collected from 10 drill cores for fracture mineral studies. The aim of the study was to obtain information about past hydrogeochemical conditions at Olkiluoto using the calcite morphology, the chemical characteristics and the isotopic composition of carbon and oxygen in calcite. The chemical composition of fracture calcites at Olkiluoto is nearly stoichiometric CaCO 3 . Most variation in the composition of calcite is due to differences in the Mn content, which could indicate variations in groundwater redox conditions. Meaningful REE patterns were obtained for the calcites. REE patterns showed generally negative Eu anomalies, but one fracture calcite specimen had a distinct positive Eu anomaly. This positive anomaly could be related to ancient hydrothermal conditions, although derivation of the anomaly from the host rock cannot be excluded. Preliminary results for calcite U-Th dating of fracture calcites are reported. The isotopic composition of U and Th were analysed by a new multiple collector LA-ICPMS instrument. U and Th concentrations in fracture calcites are generally 18 O values of calcite range from -17 to -7 per mille. Most of the calcites may have been precipitated in the presence of waters with oxygen isotope ratios similar to those in the present-day groundwaters at Olkiluoto. Two samples with an oxygen isotopic composition highly depleted in 18 O were interpreted to have been precipitated at elevated temperatures. The δ 13 C values of calcite showed a wide range of values from -26 to +35 per mille. Multiple sources for carbon are implied. The highest δ 13 C values indicate methanic conditions in the fracture at the time of calcite precipitation. It appears that the methanic environment has earlier extended to shallower depths compared to the location of the methanic environment in the present-day fracture system (> 300 m). Ten pyrite samples were analysed

Visible-light-enhanced interactions of hydrogen sulfide with composites of zinc (oxy)hydroxide with graphite oxide and graphene.

Science.gov (United States)

Seredych, Mykola; Mabayoje, Oluwaniyi; Bandosz, Teresa J

2012-01-17

Composites of zinc(oxy)hydroxide-graphite oxide and of zinc(oxy)hydroxide-graphene were used as adsorbents of hydrogen sulfide under ambient conditions. The initial and exhausted samples were characterized by XRD, FTIR, potentiometric titration, EDX, thermal analysis, and nitrogen adsorption. An increase in the amount of H(2)S adsorbed/oxidized on their surfaces in comparison with that of pure Zn(OH)(2) is linked to the structure of the composite, the relative number of terminal hydroxyls, and the kind of graphene-based phase used. Although terminal groups are activated by a photochemical process, the graphite oxide component owing to the chemical bonds with the zinc(oxy)hydroxide phase and conductive properties helps in electron transfer, leading to more efficient oxygen activation via the formation of superoxide ions. Elemental sulfur, zinc sulfide, sulfite, and sulfate are formed on the surface. The formation of sulfur compounds on the surface of zinc(oxy)hydroxide during the course of the breakthrough experiments and thus Zn(OH)(2)-ZnS heterojunctions can also contribute to the increased surface activity of our materials. The results show the superiority of graphite oxide in the formation of composites owing to its active surface chemistry and the possibility of interface bond formation, leading to an increase in the number of electron-transfer reactions. © 2011 American Chemical Society

High temperature oxidation-sulfidation behavior of Cr-Al2O3 and Nb-Al2O3 composites densified by spark plasma sintering

International Nuclear Information System (INIS)

Saucedo-Acuna, R.A.; Monreal-Romero, H.; Martinez-Villafane, A.; Chacon-Nava, J.G.; Arce-Colunga, U.; Gaona-Tiburcio, C.; De la Torre, S.D.

2007-01-01

The high temperature oxidation-sulfidation behavior of Cr-Al 2 O 3 and Nb-Al 2 O 3 composites prepared by mechanical alloying (MA) and spark plasma sintering (SPS) has been studied. These composite powders have a particular metal-ceramic interpenetrating network and excellent mechanical properties. Oxidation-sulfidation tests were carried out at 900 deg. C, in a 2.5%SO 2 + 3.6%O 2 + N 2 (balance) atmosphere for 48 h. The results revealed the influence of the sintering conditions on the specimens corrosion resistance, i.e. the Cr-Al 2 O 3 and Nb-Al 2 O 3 composite sintered at 1310 deg. C/4 min showed better corrosion resistance (lower weight gains) compared with those found for the 1440 deg. C/5 min conditions. For the former composite, a protective Cr 2 O 3 layer immediately forms upon heating, whereas for the later pest disintegration was noted. Thus, under the same sintering conditions the Nb-Al 2 O 3 composites showed the highest weight gains. The oxidation products were investigated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy

One-step hydrothermal synthesis of three-dimensional porous Ni-Co sulfide/reduced graphene oxide composite with optimal incorporation of carbon nanotubes for high performance supercapacitors

Science.gov (United States)

Chiu, Cheng-Ting; Chen, Dong-Hwang

2018-04-01

Three-dimensional (3D) porous Ni-Co sulfide/reduced graphene oxide composite with the appropriate incorporation of carbon nanotubes (NCS/rGO/CNT) was fabricated as a promising material for supercapacitor electrodes. It combined the high pseudo-capacitance of Ni-Co sulfide as well as the large specific surface area and electrical double layer capacitance of reduced graphene oxide (rGO). Carbon nanotubes (CNTs) were incorporated to act as the spacer for hindering the restacking of rGO and to construct a conductive network for enhancing the electron transport. The 3D porous NCS/rGO/CNT composite was fabricated by a facile one-step hydrothermal process in which Ni-Co sulfide nanosheets were synthesized and graphene oxide was reduced simultaneously. It was shown that the capacitance and cyclic performance indeed could be effectively improved via the appropriate addition of CNTs. In addition, a flexible all-solid-state asymmetric supercapacitor based on the NCS/rGO/CNT electrode was fabricated and exhibited the same capacitive electrochemical performance under bending. Also, it could successfully turn on a light-emitting diode light, revealing its feasibility in practical application. All results demonstrated that the developed NCS/rGO/CNT composite has potential application in supercapacitors.

Recent massive sulfide deposits of the Semenov ore district, Mid-Atlantic Ridge, 13°31' N: Associated rocks of the oceanic core complex and their hydrothermal alteration

Science.gov (United States)

Pertsev, A. N.; Bortnikov, N. S.; Vlasov, E. A.; Beltenev, V. E.; Dobretsova, I. G.; Ageeva, O. A.

2012-09-01

The oceanic core complexes and large-offset detachment faults characteristic of the slow-spreading Mid-Atlantic Ridge are crucial for the structural control of large hydrothermal systems, including those forming sub-seafloor polymetallic sulfide mineralization. The structural-geological, petrographic, and mineralogical data are considered for the oceanic core complex enclosing the Semenov-1, -2, -3, -4, and -5 inactive hydrothermal sulfide fields recently discovered on the Mid-Oceanic Ridge at 13°31' N. The oceanic core complex is composed of serpentinized and talc-replaced peridotites and sporadic gabbroic rocks, however, all hydrothermal fields reveal compositional indications of basaltic substrate. The volcanic structures superposed on the oceanic core complex are marked by outcrops of pillow lavas with fresh quenched glass. Dolerites regarded as volcanic conduits seem to represent separate dike swarms. The superposed volcanic structures develop largely along the near-latitudinal high-angle tectonic zone controlling the Semenov-1, -2, -5, and -3 hydrothermal sulfide fields. The manifestations of hydrothermal metasomatic alteration are diverse. The widespread talcose rocks with pyrrhotite-pyrite mineralization after serpentinite, as well as finding of talc-chlorite metabasalt are interpreted as products of hydrothermal activity in the permeable zone of detachment fault. Chloritization and brecciation of basalts with superposed quartz or opal, barite, and pyrite or chalcopyrite mineralization directly related to the sub-seafloor sulfide deposition. The native copper mineralization in almost unaltered basalts at the Semenov-4 field is suggested to precipitate from ore-forming fluids before they reach the level of sub-seafloor sulfide deposition. Amphibolites with plagiogranite veinlets are interpreted as tectonic fragments of the highest-temperature portions of hydrothermal systems, where partial melting of basic rocks in the presence of aqueous fluid with

Controllable synthesis of hierarchical nickel cobalt sulfide with enhanced electrochemical activity

Science.gov (United States)

Tie, Jinjin; Han, Jiaxi; Diao, Guiqiang; Liu, Jiwen; Xie, Zhuopeng; Cheng, Gao; Sun, Ming; Yu, Lin

2018-03-01

The composition of nickel cobalt sulfide has great influence on its electrochemical performance. Herein, the nickel cobalt sulfide with different composition and mixed phase were synthesized by one-step solvothermal method through changing the molar ratio of Ni to Co in the reaction system. The electrochemical measurements showed that the nickel cobalt sulfide with a theoretical molar ratio of Ni/Co to be 1.5:1.5 (NCS-2) demonstrates the superior pseudocapacitive performance with a high specific capacitance (6.47 F cm-2 at 10 mA cm-2) and a favorable Coulombic efficiency (∼99%). Whereas, when applied as the catalyst for hydrogen evolution reaction in 1 M KOH aqueous electrolyte, the nickel cobalt sulfide with a theoretical molar ratio of Ni/Co is 1:2 (NCS-1) displays better catalytic activity, and it requires a relatively lower overpotential of 282 mV to deliver the current density of 10 mA cm-2.

Localized sulfate-reducing zones in a coastal plain aquifer

Science.gov (United States)

Brown, C.J.; Coates, J.D.; Schoonen, M.A.A.

1999-01-01

High concentrations of dissolved iron in ground water of coastal plain or alluvial aquifers contribute to the biofouling of public supply wells for which treatment and remediation is costly. Many of these aquifers, however, contain zones in which microbial sulfate reduction and the associated precipitation of iron-sulfide minerals decreases iron mobility. The principal water-bearing aquifer (Magothy Aquifer of Cretaceous age) in Suffolk County, New York, contains localized sulfate-reducing zones in and near lignite deposits, which generally are associated with clay lenses. Microbial analyses of core samples amended with [14C]-acetate indicate that microbial sulfate reduction is the predominant terminal-electron-accepting process (TEAP) in poorly permeable, lignite-rich sediments at shallow depths and near the ground water divide. The sulfate-reducing zones are characterized by abundant lignite and iron-sulfide minerals, low concentrations of Fe(III) oxyhydroxides, and by proximity to clay lenses that contain pore water with relatively high concentrations of sulfate and dissolved organic carbon. The low permeability of these zones and, hence, the long residence time of ground water within them, permit the preservation and (or) allow the formation of iron-sulfide minerals, including pyrite and marcasite. Both sulfate-reducing bacteria (SRB) and iron-reducing bacteria (IRB) are present beneath and beyond the shallow sulfate-reducing zones. A unique Fe(III)-reducing organism, MD-612, was found in core sediments from a depth of 187 m near the southern shore of Long Island. The distribution of poorly permeable, lignite-rich, sulfate-reducing zones with decreased iron concentration is varied within the principal aquifer and accounts for the observed distribution of dissolved sulfate, iron, and iron sulfides in the aquifer. Locating such zones for the placement of production wells would be difficult, however, because these zones are of limited aerial extent.

Whole-rock and mineral compositional constraints on the magmatic evolution of the Ni-Cu-(PGE) sulfide ore-bearing Kevitsa intrusion, northern Finland

Science.gov (United States)

Luolavirta, Kirsi; Hanski, Eero; Maier, Wolfgang; Santaguida, Frank

2018-01-01

The 2.06 Ga mafic-ultramafic Kevitsa intrusion is located in the Central Lapland greenstone belt. The lower ultramafic part of the intrusion hosts a large disseminated Ni-Cu-(PGE) sulfide deposit with Ni tenors ranging widely from architecture, variations in whole-rock and mineral compositions, and the presence of numerous inclusions and xenoliths. The OLPXs are mainly composed of cumulus olivine (Fo77-89) and clinopyroxene (Mg#81-92) with variable amounts of oikocrystic orthopyroxene (Mg#79-84). They comprise the bulk of the ultramafic cumulates and are the dominant host rocks to the sulfide ore. The host rocks to the regular and false ore type are mineralogically and compositionally similar (Fo 80-83, mostly) and show mildly LREE-enriched REE patterns (CeN/YbN 2), characteristic for the bulk of the Kevitsa ultramafic cumulates. The abundance of orthopyroxene and magnetite is lowest in the host rocks to the Ni-PGE ore type, being in line with the mineral compositions of the silicates, which are the most primitive in the intrusion. However, it contrasts with the LREE-enriched nature of the ore type (CeN/YbN 7), indicating significant involvement of crustal material in the magma. The contrasting intrusive stratigraphy in the different parts of the intrusion likely reflects different emplacement histories. It is proposed that the Kevitsa magma chamber was initially filled by stable continuous flow ("single" input) of basaltic magma followed by differentiation in an at least nearly closed system. In the following stage, new magma pulses were repeatedly emplaced into the interior of the intrusion in a dynamic (open) system forming the sulfide ore bodies. To gain the peculiar compositional and mineralogical characteristics of the Ni-PGE ore type, the related magma probably interacted with different country rocks en route to the Kevitsa magma chamber.

Sulfidation behavior of Fe20Cr alloys

International Nuclear Information System (INIS)

Pillis, Marina Fuser

2001-01-01

Alloys for use in high temperature environments rely on the formation of an oxide layer for their protection. Normally, these protective oxides are Cr 2 O 3 , Al 2 O 3 and, some times, SiO 2 . Many industrial gaseous environments contain sulfur. Sulfides, formed in the presence of sulfur are thermodynamically less stable, have lower melting points and deviate much more stoichiometrically, compared to the corresponding oxides. The mechanism of sulfidation of various metals is as yet not clear, in spite of the concerted efforts during the last decade. To help address this situation, the sulfidation behavior of Fe20Cr has been studied as a function of compositional modifications and surface state of the alloy. The alloys Fe20Cr, Fe20Cr0.7Y, Fe20Cr5Al and Fe20Cr5Al0.6Y were prepared and three sets of sulfidation tests were carried out. In the first set, the alloys were sulfidized at 700 deg C and 800 deg C for 10h. In the second set, the alloys were pre-oxidized at 1000 deg C and then sulfidized at 800 deg C for up to 45h. In the third set of tests, the initial stages of sulfidation of the alloys was studied. All the tests were carried out in a thermobalance, in flowing H 2 /2%H 2 S, and the sulfidation behavior determined as mass change per unit area. Scanning electron microscopy coupled to energy dispersive spectroscopy and X-ray diffraction analysis were used to characterize the reaction products. The addition of Y and Al increased sulfidation resistance of Fe20Cr. The addition of Y altered the species that diffused predominantly during sulfide growth. It changed from predominant cationic diffusion to predominant anionic diffusion. The addition of Al caused an even greater increase in sulfidation resistance of Fe20Cr, with the parabolic rate constant decreasing by three orders of magnitude. Y addition to the FeCrAl alloy did not cause any appreciable alteration in sulfidation resistance. Pre-oxidation of the FeCrAl and FeCrAlY alloys resulted in an extended

Carbon a support for sulfide catalysts

NARCIS (Netherlands)

Vissers, J.P.R.; Lensing, T.J.; Mercx, F.P.M.; Beer, de V.H.J.; Prins, R.

1983-01-01

Two types of carbon materials, carbon black composite and carbon covered alumina, were studied for-their use as support for sulfide catalysts. The following parameters were varied: type of carbon black, carbon coverage of the alumina and carbon pretreatment. Pore size distributions were determined

The investigation on physico-chemical conditions of sulfides and sulfates based on petrographic and sulfur - oxygen stable isotope studies from the Darreh-Zar porphyry copper deposit, Kerman

Directory of Open Access Journals (Sweden)

Anis Parsapoor

2014-04-01

Full Text Available The Darreh-Zar porphyry copper deposit, located in the Urumieh – Dokhtar magmatic belt, lies about 10 km southeast of Sar-Cheshmeh porphyry copper deposit. The ore body with hydrothermally altered zones including potassic, chlorite-sericite, sericite, argillic and propylitic all related to the Darreh-Zar porphyry stock intruded the Eocene volcanic rocks. Pyrite, chalcopyrite, molybdenite, with different textures as disseminated and veinlet, are the major sulfide minerals and chalcocite and covellite are considered as the secondary minerals. Sulfur isotopic composition of the sulfates and sulfides studied fall on the magmatic values. Two different origins may be suggested for the gypsums studied: 1- hydration of anhydrite and 2- oxidation of pyrite during supergene enrichment. The stable isotopic data calculated on couple minerals (pyrite-anhydrite point to the formation temperature of about 485-515οC for the fluids involved in mineralization. The fluid responsible for mineralization suggests magmatic sources for all sulfide phases and reduced aqueous sulfur species. Isotopic zoning, based on the δ34S pyrite values, divided the area into the east and the west parts with negative and positive correlation against the depth, respectively. Also, a negative correlation is observed between the Cu and the δ34S in the eastern portion of the area.

Separation of platinum metals by theirs extraction as sulfides

International Nuclear Information System (INIS)

Pilipenko, A.T.; Ryabushko, O.P.; Ty Van Mak

1978-01-01

Separation of platinum metals by means of their sediment in the form of sulfides with subsequent extraction is studied. The optimum conditions of metal sulfide extraction are determined, the metal output dependence from acidness and aqueous phase composition and also the organic solvent nature are investigated. Ruthenium concentration was determined photometrically. Ruthenium sulfide is extracted by butyl spirit from 1-4 normal hydrochloric acid. The maximum extraction grade of 63% is reached in 3.2-normal acid. When the mixture of acetic and hydrochloric acids (2:1) is used for decomposition of ruthenium tiosalts, the grade of ruthenium extraction by amyl spirit or the mixture of anyl and butyl spirits (1:1) constitutes 100%

Functional consortium for denitrifying sulfide removal process.

Science.gov (United States)

Chen, Chuan; Ren, Nanqi; Wang, Aijie; Liu, Lihong; Lee, Duu-Jong

2010-03-01

Denitrifying sulfide removal (DSR) process simultaneously converts sulfide, nitrate, and chemical oxygen demand from industrial wastewaters to elemental sulfur, nitrogen gas, and carbon dioxide, respectively. This investigation utilizes a dilution-to-extinction approach at 10(-2) to 10(-6) dilutions to elucidate the correlation between the composition of the microbial community and the DSR performance. In the original suspension and in 10(-2) dilution, the strains Stenotrophomonas sp., Thauera sp., and Azoarcus sp. are the heterotrophic denitrifiers and the strains Paracoccus sp. and Pseudomonas sp. are the sulfide-oxidizing denitrifers. The 10(-4) dilution is identified as the functional consortium for the present DSR system, which comprises two functional strains, Stenotrophomonas sp. strain Paracoccus sp. At 10(-6) dilution, all DSR performance was lost. The functions of the constituent cells in the DSR granules were discussed based on data obtained using the dilution-to-extinction approach.

Indium sulfide precipitation from hydrochloric acid solutions of calcium and sodium chlorides

International Nuclear Information System (INIS)

Kochetkova, N.V.; Bayandina, Yu.E.; Toptygina, G.M.; Shepot'ko, A.O.

1988-01-01

The effect of precipitation duration, acid concentration, indium complexing with chloride ions on the process of indium sulfide chemical precipitation in hydrochloric acid solutions, precipitate composition and dispersity are studied. It is established that indium sulfide solubility increases in solutions with acid concentration exceeding 0.40-0.45 mol/l. Calcium and indium chloride addition to diluted hydrochloric solutions greatly increases the solubility of indium sulfide. The effect of calcium chloride on In 2 S 3 solubility is higher than that of sodium chloride

Uncharged positive electrode composition

Science.gov (United States)

Kaun, Thomas D.; Vissers, Donald R.; Shimotake, Hiroshi

1977-03-08

An uncharged positive-electrode composition contains particulate lithium sulfide, another alkali metal or alkaline earth metal compound other than sulfide, e.g., lithium carbide, and a transition metal powder. The composition along with a binder, such as electrolytic salt or a thermosetting resin is applied onto an electrically conductive substrate to form a plaque. The plaque is assembled as a positive electrode within an electrochemical cell opposite to a negative electrode containing a material such as aluminum or silicon for alloying with lithium. During charging, lithium alloy is formed within the negative electrode and transition metal sulfide such as iron sulfide is produced within the positive electrode. Excess negative electrode capacity over that from the transition metal sulfide is provided due to the electrochemical reaction of the other than sulfide alkali metal or alkaline earth metal compound.

Chemical composition of different muscle zones in pirarucu (Arapaima gigas

Directory of Open Access Journals (Sweden)

Mayara Galvão MARTINS

Full Text Available Abstract Identifying potential patterns in pirarucu (Arapaima gigas composition, as a function of the different fish muscle zones (dorse, venter, ventrecha and tail, was the main objective of this research. For such, the different pirarucu muscle zones were evaluated, in order to obtain proximate composition and minerals content. It was also determined amino acids and fatty acids contents in fish muscle. The dorsal, ventral and tail muscle zones presented similar moisture (76.5-78.2%, protein (17.8-18.9%, total lipids (1.0-1.5% and ash (0.9-1.2% contents. On the other hand, the ventrecha zone presented 25.8% of protein and the major total lipids content (17.1%. The main minerals found in fish muscle were K (183.5-288.6 mg/100 g muscle and Na (65.1-175.5 mg/100 g. Glutamic acid (3027.6 mg/100 g muscle was the main amino acid found in fish muscle, which presented 48% of essential amino acids in the protein fraction. Lipids content showed 57.3% of unsaturated fatty acids and 42.7% of saturated fatty acids.

The origin and isotopic composition of dissolved sulfide in groundwater from carbonate aquifers in Florida and Texas

International Nuclear Information System (INIS)

Rye, R.O.; Back, W.; Hanshaw, B.B.; Rightmire, C.T.; Pearson, F.J. Jr.

1981-01-01

The delta 34 S values of dissolved sulfide and the sulfur isotope fractionations between dissolved sulfide and sulfate species in Floridan ground water generally correlate with dissolved sulfate concentrations which are related to flow patterns and residence time within the aquifer. The dissolved sulfide derives from the slow in situ biogenic reduction of sulfate dissolved from sedimentary gypsum in the aquifer. In areas where the water is oldest, the dissolved sulfide has apparently attained isotopic equilibrium with the dissolved sulfate at the temperature of the system. This approach to equilibrium reflects an extremely slow reduction rate of the dissolved sulfate by bacteria; this slow rate probably results from very low concentrations of organic matter in the aquifer. In the reducing part of the Edwards aquifer, Texas, there is a general down-gradient increase in both dissolved sulfide and sulfate concentrations, but neither the delta 34 S values of sulfide nor the sulfide-sulfate isotope fractionation correlates with the ground-water flow pattern. The dissolved sulfide species appear to be derived primarily from biogenic reduction of sulfate ions whose source is gypsum dissolution although upgradient diffusion of H 2 S gas from deeper oil field brines may be important in places. (author)

Growth and chemosensory behavior of sulfate-reducing bacteria in oxygen-sulfide gradients

DEFF Research Database (Denmark)

Sass, Andrea M.; Wieland, Andrea Eschemann; Kühl, Michael

2002-01-01

Growth and chemotactic behavior in oxic–anoxic gradients were studied with two freshwater and four marine strains of sulfate-reducing bacteria related to the genera Desulfovibrio, Desulfomicrobium or Desulfobulbus. Cells were grown in oxygen–sulfide counter-gradients within tubes filled with agar...... chemotactically to lactate, nitrate, sulfate and thiosulfate, and even sulfide functioned as an attractant. In oxic–anoxic gradients the bacteria moved away from high oxygen concentrations and formed bands at the outer edge of the oxic zone at low oxygen concentration (... to actively change the extension and slope of the gradients by oxygen reduction with lactate or even sulfide as electron donor. Generally, the chemotactic behavior was in agreement with a defense strategy that re-establishes anoxic conditions, thus promoting anaerobic growth and, in a natural community...

Understanding hydrodenitrogenation on novel unsupported sulfide Mo-W-Ni catalysis

Energy Technology Data Exchange (ETDEWEB)

Hein, J.; Hrabar, A.; Gutierrez, O.Y.; Lercher, J.A. [Technische Univ. Muenchen (Germany). Catalysis Research Center

2011-07-01

WNi, NiMo and Mo-W-Ni unsupported catalysts were synthesized, characterized and tested with respect to their hydrodenitrogenation properties using o-propylaniline as test reactant. The bimetallic oxide precursors are crystalline metallates, whereas the trimetallic materials are amorphous. In the sulfide form, the catalysts are mixtures of agglomerated Mo(W)S{sub 2} and Ni sulfides. The performance of all catalysts is similar, suggesting the same nature of active sites regardless the composition. Due to the lack of correlation between activity and density of coordinatively unsaturated sites of the catalysts, two kinds of active sites are proposed, i.e. coordinatively unsaturated sites and electron rich sites at the edges of the sulfides. (orig.)

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.

Genesis of copper-lead mineralization in the regionally zoned Agnigundala Sulfide Belt, Cuddapah Basin, Andhra Pradesh, India

Science.gov (United States)

Bhattacharya, H. N.; Bandyopadhyay, Sandip

2018-03-01

Shallow marine sandstone-shale-carbonate sedimentary rocks of the Paleoproterozoic northern Cuddapah basin host copper (Nallakonda deposit), copper-lead (Dhukonda deposit), and lead mineralization (Bandalamottu deposit) which together constitute the Agnigundala Sulfide Belt. The Cu sulfide mineralization in sandstone is both stratabound and disseminated, and Pb sulfide mineralization occurs as stratabound fracture filling veins and/or replacement veins within dolomite. Systematic mineralogical and sulfur, carbon, and oxygen isotope studies of the three deposits indicate a common ore-fluid that deposited copper at Nallakonda, copper-lead at Dhukonda, and lead at Bandalamottu under progressive cooling during migration through sediments. The ore-fluid was of low temperature (water sulfate produced sulfide for ore deposition. It is envisaged that basal red-bed and evaporite-bearing rift-related continental to shallow marine sediments might have acted as the source for the metals. Rift-related faults developed during sedimentation in the basin might have punctured the ore-fluid pool in the lower sedimentary succession and also acted as conduits for their upward migration. The ore-bearing horizons have participated in deformations during basin inversion without any recognizable remobilization.

Hydrogen sulfide generation in shipboard oily-water waste. Part 3. Ship factors

Energy Technology Data Exchange (ETDEWEB)

Hodgeman, D.K.; Fletcher, L.E.; Upsher, F.J.

1995-04-01

The chemical and microbiological composition of bilge-water in ships of the Royal Australian Navy has been investigated in relation to the formation of hydrogen sulfide by sulfate-reducing bacteria. Sulfate-reducing bacteria were found in most ships in populations up to 800,000 per mL. Sulfate in the wastes is provided by sea-water. Sea-water constitutes up to 60% (median 20%) of the wastes analysed. Evidence for generation of hydrogen sulfide in the ships was found directly as sulfide or indirectly as depressed sulfate concentrations. The low levels of sulfide found in bilge-water from machinery spaces suggested the ventilation systems were effectively removing the gas from the working area. The effect of storage of the wastes under conditions which simulated the oily- water holding tanks of ships were also investigated. Some wastes were found to produce large quantities of hydrogen sulfide on storage. The wastes that failed to produce hydrogen sulfide were investigated to identify any specific nutritional deficiencies. Some organic substances present in bilge-water, such as lactate or biodegradable cleaning agents, and phosphate strongly influenced the generation of hydrogen sulfide in stored oily-water wastes.

High temperature oxidation-sulfidation behavior of Cr-Al{sub 2}O{sub 3} and Nb-Al{sub 2}O{sub 3} composites densified by spark plasma sintering

Energy Technology Data Exchange (ETDEWEB)

Saucedo-Acuna, R.A. [Instituto e Ingenieria y Tecnologia, Universidad Autonoma de Cd. Juarez, Av. Del Charro 450 Norte, Col. Partido Romero, C.P. 32310, Cd. Juarez, Chihuahua (Mexico); Monreal-Romero, H.; Martinez-Villafane, A. [Centro de Investigacion en Materiales Avanzados, Departamento de Fisica de Materiales, Miguel de Cervantes 120, Complejo Industrial Chihuahua, C.P. 31109, Chihuahua (Mexico); Chacon-Nava, J.G. [Centro de Investigacion en Materiales Avanzados, Departamento de Fisica de Materiales, Miguel de Cervantes 120, Complejo Industrial Chihuahua, C.P. 31109, Chihuahua (Mexico)], E-mail: jose.chacon@cimav.edu.mx; Arce-Colunga, U. [Centro de Investigacion en Materiales Avanzados, Departamento de Fisica de Materiales, Miguel de Cervantes 120, Complejo Industrial Chihuahua, C.P. 31109, Chihuahua (Mexico); Universidad Autonoma de Tamaulipas, Matamoros 8 y 9 Col. Centro C.P. 87110, Cd. Victoria, Tamaulipas (Mexico); Gaona-Tiburcio, C. [Centro de Investigacion en Materiales Avanzados, Departamento de Fisica de Materiales, Miguel de Cervantes 120, Complejo Industrial Chihuahua, C.P. 31109, Chihuahua (Mexico); De la Torre, S.D. [Centro de Investigacion e Innovacion Tecnologica (CIITEC)-IPN, D.F. Mexico (Mexico)

2007-12-15

The high temperature oxidation-sulfidation behavior of Cr-Al{sub 2}O{sub 3} and Nb-Al{sub 2}O{sub 3} composites prepared by mechanical alloying (MA) and spark plasma sintering (SPS) has been studied. These composite powders have a particular metal-ceramic interpenetrating network and excellent mechanical properties. Oxidation-sulfidation tests were carried out at 900 deg. C, in a 2.5%SO{sub 2} + 3.6%O{sub 2} + N{sub 2}(balance) atmosphere for 48 h. The results revealed the influence of the sintering conditions on the specimens corrosion resistance, i.e. the Cr-Al{sub 2}O{sub 3} and Nb-Al{sub 2}O{sub 3} composite sintered at 1310 deg. C/4 min showed better corrosion resistance (lower weight gains) compared with those found for the 1440 deg. C/5 min conditions. For the former composite, a protective Cr{sub 2}O{sub 3} layer immediately forms upon heating, whereas for the later pest disintegration was noted. Thus, under the same sintering conditions the Nb-Al{sub 2}O{sub 3} composites showed the highest weight gains. The oxidation products were investigated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy.

Distribution and Composition of Thiotrophic Mats in the Hypoxic Zone of the Black Sea (150-170 m Water Depth, Crimea Margin).

Science.gov (United States)

Jessen, Gerdhard L; Lichtschlag, Anna; Struck, Ulrich; Boetius, Antje

2016-01-01

At the Black Sea chemocline, oxygen- and sulfide-rich waters meet and form a niche for thiotrophic pelagic bacteria. Here we investigated an area of the Northwestern Black Sea off Crimea close to the shelf break, where the chemocline reaches the seafloor at around 150-170 m water depth, to assess whether thiotrophic bacteria are favored in this zone. Seafloor video transects were carried out with the submersible JAGO covering 20 km(2) on the region between 110 and 200 m depth. Around the chemocline we observed irregular seafloor depressions, covered with whitish mats of large filamentous bacteria. These comprised 25-55% of the seafloor, forming a belt of 3 km width around the chemocline. Cores from the mats obtained with JAGO showed higher accumulations of organic matter under the mats compared to mat-free sediments. The mat-forming bacteria were related to Beggiatoa-like large filamentous sulfur bacteria based on 16S rRNA sequences from the mat, and visual characteristics. The microbial community under the mats was significantly different from the surrounding sediments and enriched with taxa affiliated with polymer degrading, fermenting and sulfate reducing microorganisms. Under the mats, higher organic matter accumulation, as well as higher remineralization and radiotracer-based sulfate reduction rates were measured compared to outside the mat. Mat-covered and mat-free sediments showed similar degradability of the bulk organic matter pool, suggesting that the higher sulfide fluxes and subsequent development of the thiotrophic mats in the patches are consequences of the accumulation of organic matter rather than its qualitative composition. Our observations suggest that the key factors for the distribution of thiotrophic mat-forming communities near to the Crimean shelf break are hypoxic conditions that (i) repress grazers, (ii) enhance the accumulation and degradation of labile organic matter by sulfate-reducers, and (iii) favor thiotrophic filamentous bacteria

Reactivity of sulfide-containing silane toward boehmite and in situ modified rubber/boehmite composites by the silane

Science.gov (United States)

Lin, Tengfei; Zhu, Lixin; Chen, Weiwei; Wu, Siwu; Guo, Baochun; Jia, Demin

2013-09-01

The silanization reaction between boehmite (BM) nanoplatelets and bis-[3-(triethoxysilyl)-propyl]-tetrasulfide (TESPT) was characterized in detail. Via such modification process, the grafted sulfide moieties on the BM endow reactivity toward rubber and substantially improved hydrophobicity for BM. Accordingly, TESPT was employed as in situ modifier for the nitrile rubber (NBR)/BM compounds to improve the mechanical properties of the reinforced vulcanizates. The effects of BM content and in situ modification on the mechanical properties, curing characteristics and morphology were investigated. BM was found to be effective in improving the mechanical performance of NBR vulcanizates. The NBR/BM composites could be further strengthened by the incorporation of TESPT. The interfacial adhesion of NBR/BM composites was obviously improved by the addition of TESPT. The substantially improved mechanical performance was correlated to the interfacial reaction and the improved dispersion of BM in rubber matrix.

Printed hydrogen sulfide gas sensor on paper substrate based on polyaniline composite

International Nuclear Information System (INIS)

Sarfraz, J.; Ihalainen, P.; Määttänen, A.; Peltonen, J.; Lindén, M.

2013-01-01

The fabrication of a hydrogen sulfide (H 2 S) sensor based on polyaniline (PANI)-metal salt (CuCl 2 ) composite is demonstrated. The sensing film was produced by screen printing and spray coating of the sensing material on interdigitated silver electrodes inkjet-printed on a paper substrate. The H 2 S sensing functionality with respect to pH and metal salt concentration was optimized. In addition, the long term stability and humidity effects on the sensor performance were investigated. The printed chemiresistors showed more than five orders of magnitude change in resistance within 20 min of exposure of 15 ppm H 2 S at room temperature. The relatively fast kinetics and large response of the sensor can be explained by the formation of Cu 2 S and subsequent protonation of PANI. In addition, the relatively large roughness and porosity of the paper substrate offers an increased surface sensing area. - Highlights: • pH, salt concentration, film thickness, cross sensitivity • Printed sensor on paper substrate • Commercial polyaniline against special morphologies

An Experimental Study of Low-Temperature Sulfurization of Carbohydrates Using Various Sulfides Reveals Insights into Structural Characteristics and Sulfur Isotope Compositions of Macromolecular Organic Matter in the Environment

Science.gov (United States)

OBeirne, M. D.; Werne, J. P.; Van Dongen, B.; Gilhooly, W., III

2017-12-01

Sulfurization of carbohydrates has been suggested as an important mechanism for the preservation of organic matter in anoxic/euxinic depositional environments. In this study, glucose was sulfurized under laboratory conditions at room temperature (24°C) using three commercially available sulfides - ammonium sulfide ([NH4]2S), sodium sulfide (Na2S), and sodium hydrosulfide (NaHS), each mixed with elemental sulfur to produce polysulfide solutions. The reaction products were analyzed using Fourier transform infrared spectroscopy (FTIR), which revealed structural differences among the products formed via the three sulfide reactants. Additionally, analysis of the bulk sulfur isotope compositions of reactants and products was used to determine the fractionation(s) associated with abiotic sulfur incorporation into organic matter. Samples from both modern (Mahoney Lake, British Colombia, Canada) and ancient (Jurassic aged Blackstone Band from the Kimmeridge Clay Formation, Dorset, United Kingdom) euxinic systems were also analyzed for comparison to laboratory samples. Results from this study provide experimental evidence for the structural and sulfur isotopic relationships of sulfurized organic matter in the geosphere.

Selenium Sulfide

Science.gov (United States)

Selenium sulfide, an anti-infective agent, relieves itching and flaking of the scalp and removes the dry, ... Selenium sulfide comes in a lotion and is usually applied as a shampoo. As a shampoo, selenium ...

Neutron diffraction investigations of the superionic conductors lithium sulfide and sodium sulfide

International Nuclear Information System (INIS)

Altorfer, F.

1990-03-01

Statics and dynamics of the superionic conductors lithium sulfide and sodium sulfide were investigated using the following experimental methods: elastic scattering on sodium sulfide powder in the temperature range 20 - 1000 C, elastic scattering on a lithium sulfide single crystal in the temperature range 20 - 700 C, inelastic scattering on a 7 Li 2 S single crystal at 10 K. 34 figs., 2 tabs., 10 refs

Rock magnetic properties in the sulfate reduction zone in IODP 350 Hole 1437B, Izu Bonin rear arc: preliminary results

Science.gov (United States)

Musgrave, R. J.; Kars, M. A. C.; Kodama, K.

2014-12-01

During the northern Spring 2014 (April-May), IODP Expedition 350 drilled a 1806.5 m deep hole at Site U1437 in the Izu-Bonin rear arc, in order to understand, among other objectives, the compositional evolution of the arc since the Miocene and track the missing half of the subduction factory. The good recovery of mostly fine grained sediments at this site enables a high resolution paleomagnetic and rock magnetic study. Particularly, variations in magnetic properties and mineralogy are well documented. The onboard magnetostratigraphy established from the study of the archive halves highlighted remagnetized intervals that produced "ghost" repetitions of geomagnetic reversals ~10's meters below their actual stratigraphic position in specific intervals. Onboard paleo- and rock magnetic analyses showed that remagnetization is probably due to a chemical remanence carried by iron sulfides (putatively identified as greigite). The rock magnetic parameters, SIRM/k and the S-ratio are consistent with the presence of ferromagnetic iron sulfides in Site U1437. A mixture of iron oxides and iron sulfides was found within the sulfate reduction zone, which was identified by onboard pore water analyses at ~50-60 meters below sea floor (mbsf) by a minimum in sulfate (~5 mM) coupled with a maximum in alkalinity. Below 50 mbsf, the sulfate content increases up to ~29 mM at ~460 mbsf. The particular downhole profile of the sulfate content in Site U1437 is probably triggered by fluid circulation. Evolution of sulfate content, pyritization process and fluid circulation are closely linked. Onshore research is focusing on further downhole characterization of the iron sulfides including their abundance, grain size and composition. Routine magnetic properties (NRM, magnetic susceptibility) and rock magnetic analyses at high resolution (every ~20-50 cm), including hysteresis properties and low temperature magnetic measurements, have been conducted on about 400 discrete samples in the first 200

Distribution and Composition of Thiotrophic Mats in the Hypoxic Zone of the Black Sea (150–170 m Water Depth, Crimea Margin)

Science.gov (United States)

Jessen, Gerdhard L.; Lichtschlag, Anna; Struck, Ulrich; Boetius, Antje

2016-01-01

At the Black Sea chemocline, oxygen- and sulfide-rich waters meet and form a niche for thiotrophic pelagic bacteria. Here we investigated an area of the Northwestern Black Sea off Crimea close to the shelf break, where the chemocline reaches the seafloor at around 150–170 m water depth, to assess whether thiotrophic bacteria are favored in this zone. Seafloor video transects were carried out with the submersible JAGO covering 20 km2 on the region between 110 and 200 m depth. Around the chemocline we observed irregular seafloor depressions, covered with whitish mats of large filamentous bacteria. These comprised 25–55% of the seafloor, forming a belt of 3 km width around the chemocline. Cores from the mats obtained with JAGO showed higher accumulations of organic matter under the mats compared to mat-free sediments. The mat-forming bacteria were related to Beggiatoa-like large filamentous sulfur bacteria based on 16S rRNA sequences from the mat, and visual characteristics. The microbial community under the mats was significantly different from the surrounding sediments and enriched with taxa affiliated with polymer degrading, fermenting and sulfate reducing microorganisms. Under the mats, higher organic matter accumulation, as well as higher remineralization and radiotracer-based sulfate reduction rates were measured compared to outside the mat. Mat-covered and mat-free sediments showed similar degradability of the bulk organic matter pool, suggesting that the higher sulfide fluxes and subsequent development of the thiotrophic mats in the patches are consequences of the accumulation of organic matter rather than its qualitative composition. Our observations suggest that the key factors for the distribution of thiotrophic mat-forming communities near to the Crimean shelf break are hypoxic conditions that (i) repress grazers, (ii) enhance the accumulation and degradation of labile organic matter by sulfate-reducers, and (iii) favor thiotrophic filamentous bacteria

Molybdenum isotope fractionation and speciation in a euxinic lake—Testing ways to discern isotope fractionation processes in a sulfidic setting

Energy Technology Data Exchange (ETDEWEB)

Dahl, Tais W.; Wirth, Stefanie B.

2017-06-01

The molybdenum (Mo) isotope composition in euxinic shales has been used as a proxy for the global distribution of anoxic conditions in ancient oceans, and since more recently also as a proxy for sulfide concentrations in depositional environments. However, there is currently no way to distinguish isotope fractionation at low bottom water sulfide concentrations in ‘local’ basins from ‘global’ secular isotope variations associated with changing seawater composition. This uncertainty is challenging the use of Mo isotopes for paleoceanographic reconstructions. To explore this further, we present new data from sediments deposited over the past ~ 9800 years in one of the best studied euxinic localities in the world: Lake Cadagno in Switzerland. The sample set allows us to test ways to discern isotope fractionation processes at play in a highly restricted euxinic basin. Most of our drill core samples (n = 18) show high δ98Mo values similar to previously studied shallow sediments, indicative of quantitative Mo removal from the water column (Dahl et al. 2010a). However, a few samples (n = 3) deposited between about 1200 and 3400 years ago carry low δ98Mo values and have been isotopically fractionated in the lake. Sedimentological and geochemical characterizations show that these δ98Mo-fractionated sediments formed during times of frequent injection of O2- and sediment-rich river water into the deep sulfidic water column. A positive correlation between δ98Mo and sedimentary Mo contents suggests that isotope fractionation occurred during times of non-quantitative Mo removal, although Mn-oxide cycling at the chemocline might also contribute a subordinate proportion of (98Mo-depleted) molybdenum into the sulfidic zone. Sedimentary Mo/U enrichments relative to oxic lake water further supports the hypothesis that a particulate Mo shuttle was most efficient during times of quantitative Mo removal. Therefore, periods with inefficient Mo capture are ascribed to

Corrosion resistance of cement brick on an organo-mineral base in a hydrogen sulfide medium

Energy Technology Data Exchange (ETDEWEB)

Potapov, A G; Belousov, G A; Pustovalov, V I; Skorikov, B M

1981-01-01

Results are presented of strength tests of cement brick made of different types of cement as a function of the composition of the mixing liquid and storage conditions. It is established that cement brick made of cement on a cinder base mixed in hydrogen sulfide water possesses the highest corrosive resistance to hydrogen sulfide attack. A marked increase in corrosion resistance is observed in cement brick on an organo-mineral base. Results of industrial tests of organo-mineral grouting mortar in a hydrogen sulfide medium are demonstrated.

Effects of resin content and preparing conditions on the properties of polyphenylene sulfide resin/graphite composite for bipolar plate

Energy Technology Data Exchange (ETDEWEB)

Xia, Li-gang; Li, Ai-ju; Yin, Qiang [Key Laboratory for Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Shandong Key Laboratory of Engineering Ceramics, Shandong University, Jinan 250061 (China); Wang, Wei-qiang [School of Mechanical Engineering, Shandong University, Jinan 250061 (China); Lin, Heng; Zhao, Yi-bo [School of Material Science and Engineering, Shandong University, Jinan 250061 (China)

2008-03-15

In the paper, a kind of polyphenylene sulfide (PPS) resin/graphite (G) composite for bipolar plate was prepared by using the PPS resin as adhesive and simple hot pressing. The influences of the resin content, the molding temperature and holding time on the conductivity and the bending strength of the PPS/G composite bipolar plate were investigated firstly and then the optimum content and the preparing conditions of the composite were obtained. The experimental results show that the electrical conductivity decreases and the bending strength reveals a serrated variation with increase in PPS resin content; when the holding time is certain, the conductivity decreases and the bending strength increases with the molding temperature increasing. The experimental results further show that the effect of the holding time on the properties of the composite is different at different molding temperatures. The PPS/G composite with 20% PPS resin content has electrical conductivity of 118.9 S cm{sup -1} and bending strength of 52.4 MPa when it molded at 380 C for 30 min, and has electrical conductivity of 105 S cm{sup -1}, bending strength of 55.7 MPa when it molded at 390 C for 30 min. The properties of the composites can meet the requirements of United States Department of Energy (DOE). (author)

Enrichment and immobilization of sulfide removal microbiota applied for environmental biological remediation of aquaculture area

International Nuclear Information System (INIS)

Zhao, Yang-Guo; Zheng, Yu; Tian, Weijun; Bai, Jie; Feng, Gong; Guo, Liang; Gao, Mengchun

2016-01-01

To remove sulfide in the deteriorating aquaculture sediment and water, sulfide-oxidizing microbiota was enriched from Jiaozhou Bay, China, by using sulfide-rich medium. Composition and structure of microbial communities in the enrichments were investigated by 16S rDNA molecular biotechniques. Results showed that microbial community structure continuously shifted and the abundance of sulfate reducing bacteria, i.e., Desulfobacterium, Desulfococcus and Desulfobacca apparently declined. Several halophile genera, Vibrio, Marinobacter, Pseudomonas, Prochlorococcus, Pediococcus and Thiobacillus predominated finally in the microbiota. The enriched microbiota was capable of removing a maximum of 1000 mg/L sulfide within 12 h with 10% inoculum at pH 7.0, 20–30 °C. After immobilized, the microbiota presented excellent resistance to impact and could completely remove 600 mg/L sulfide in 12 h. Moreover, the immobilized microbiota recovered well even recycled for five times. In conclusion, the immobilized sulfide-removing microbiota showed a quite promising application for biological restoring of sulfide-rich aquaculture environment. - Highlights: • A sulfide-oxidizing microbiota successfully enriched from aquaculture sediment. • Microbiota dominated by Vibrio, Marinobacter, Pseudomonas and Thiobacillus spp. • Sulfide-oxidizing microbiota removed sulfide at an average rate of 100 mg/(L·h). • Immobilized microbiota removed over 85% of sulfide even recycled for five times.

Differential responses of the freshwater wetland species Juncus effusus L. and Caltha palustris L. to iron supply in sulfidic environments

International Nuclear Information System (INIS)

Welle, Marlies E.W. van der; Niggebrugge, Karla; Lamers, Leon P.M.; Roelofs, Jan G.M.

2007-01-01

Sulfur pollution can lead to serious problems in freshwater wetlands, including phosphorus eutrophication and sulfide toxicity. We tested the effects of anaerobic iron-rich groundwater discharge in fens, simulated by iron injection, on two characteristic species (Juncus effusus and Caltha palustris) in a sulfidic environment. Biomass production of C. palustris roots showed an optimum response to the combined addition of iron and sulfide, with highest values at intermediate concentrations of both substances. Iron deficiency apparently occurred at low iron concentrations, while at high iron concentrations, growth was decreased. For J. effusus, in contrast, no toxic effects were found of both iron and sulfide. This could be explained by larger radial oxygen loss (ROL) of J. effusus and could not be explained by differences in phosphorous concentrations. The results of our experiments confirm that iron-rich groundwater discharge has the potential to affect vegetation composition through toxicity modification in sulfidic environments. - Toxicity of iron and sulfide are interacting with each other and have the potential to affect vegetation composition

Unc-51 controls active zone density and protein composition by downregulating ERK signaling.

Science.gov (United States)

Wairkar, Yogesh P; Toda, Hirofumi; Mochizuki, Hiroaki; Furukubo-Tokunaga, Katsuo; Tomoda, Toshifumi; Diantonio, Aaron

2009-01-14

Efficient synaptic transmission requires the apposition of neurotransmitter release sites opposite clusters of postsynaptic neurotransmitter receptors. Transmitter is released at active zones, which are composed of a large complex of proteins necessary for synaptic development and function. Many active zone proteins have been identified, but little is known of the mechanisms that ensure that each active zone receives the proper complement of proteins. Here we use a genetic analysis in Drosophila to demonstrate that the serine threonine kinase Unc-51 acts in the presynaptic motoneuron to regulate the localization of the active zone protein Bruchpilot opposite to glutamate receptors at each synapse. In the absence of Unc-51, many glutamate receptor clusters are unapposed to Bruchpilot, and ultrastructural analysis demonstrates that fewer active zones contain dense body T-bars. In addition to the presence of these aberrant synapses, there is also a decrease in the density of all synapses. This decrease in synaptic density and abnormal active zone composition is associated with impaired evoked transmitter release. Mechanistically, Unc-51 inhibits the activity of the MAP kinase ERK to promote synaptic development. In the unc-51 mutant, increased ERK activity leads to the decrease in synaptic density and the absence of Bruchpilot from many synapses. Hence, activated ERK negatively regulates synapse formation, resulting in either the absence of active zones or the formation of active zones without their proper complement of proteins. The Unc-51-dependent inhibition of ERK activity provides a potential mechanism for synapse-specific control of active zone protein composition and release probability.

Transient Kinetic Analysis of Hydrogen Sulfide Oxidation Catalyzed by Human Sulfide Quinone Oxidoreductase*

Science.gov (United States)

Mishanina, Tatiana V.; Yadav, Pramod K.; Ballou, David P.; Banerjee, Ruma

2015-01-01

The first step in the mitochondrial sulfide oxidation pathway is catalyzed by sulfide quinone oxidoreductase (SQR), which belongs to the family of flavoprotein disulfide oxidoreductases. During the catalytic cycle, the flavin cofactor is intermittently reduced by sulfide and oxidized by ubiquinone, linking H2S oxidation to the electron transfer chain and to energy metabolism. Human SQR can use multiple thiophilic acceptors, including sulfide, sulfite, and glutathione, to form as products, hydrodisulfide, thiosulfate, and glutathione persulfide, respectively. In this study, we have used transient kinetics to examine the mechanism of the flavin reductive half-reaction and have determined the redox potential of the bound flavin to be −123 ± 7 mV. We observe formation of an unusually intense charge-transfer (CT) complex when the enzyme is exposed to sulfide and unexpectedly, when it is exposed to sulfite. In the canonical reaction, sulfide serves as the sulfur donor and sulfite serves as the acceptor, forming thiosulfate. We show that thiosulfate is also formed when sulfide is added to the sulfite-induced CT intermediate, representing a new mechanism for thiosulfate formation. The CT complex is formed at a kinetically competent rate by reaction with sulfide but not with sulfite. Our study indicates that sulfide addition to the active site disulfide is preferred under normal turnover conditions. However, under pathological conditions when sulfite concentrations are high, sulfite could compete with sulfide for addition to the active site disulfide, leading to attenuation of SQR activity and to an alternate route for thiosulfate formation. PMID:26318450

Transient Kinetic Analysis of Hydrogen Sulfide Oxidation Catalyzed by Human Sulfide Quinone Oxidoreductase.

Science.gov (United States)

Mishanina, Tatiana V; Yadav, Pramod K; Ballou, David P; Banerjee, Ruma

2015-10-09

The first step in the mitochondrial sulfide oxidation pathway is catalyzed by sulfide quinone oxidoreductase (SQR), which belongs to the family of flavoprotein disulfide oxidoreductases. During the catalytic cycle, the flavin cofactor is intermittently reduced by sulfide and oxidized by ubiquinone, linking H2S oxidation to the electron transfer chain and to energy metabolism. Human SQR can use multiple thiophilic acceptors, including sulfide, sulfite, and glutathione, to form as products, hydrodisulfide, thiosulfate, and glutathione persulfide, respectively. In this study, we have used transient kinetics to examine the mechanism of the flavin reductive half-reaction and have determined the redox potential of the bound flavin to be -123 ± 7 mV. We observe formation of an unusually intense charge-transfer (CT) complex when the enzyme is exposed to sulfide and unexpectedly, when it is exposed to sulfite. In the canonical reaction, sulfide serves as the sulfur donor and sulfite serves as the acceptor, forming thiosulfate. We show that thiosulfate is also formed when sulfide is added to the sulfite-induced CT intermediate, representing a new mechanism for thiosulfate formation. The CT complex is formed at a kinetically competent rate by reaction with sulfide but not with sulfite. Our study indicates that sulfide addition to the active site disulfide is preferred under normal turnover conditions. However, under pathological conditions when sulfite concentrations are high, sulfite could compete with sulfide for addition to the active site disulfide, leading to attenuation of SQR activity and to an alternate route for thiosulfate formation. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Volcanic sulfur degassing and the role of sulfides in controlling volcanic metal emissions

Science.gov (United States)

Edmonds, M.; Liu, E.

2017-12-01

Volcanoes emit prodigious quantities of sulfur and metals, their behaviour inextricably linked through pre-eruptive sulfide systematics and through degassing and speciation in the volcanic plume. Fundamental differences exist in the metal output of ocean island versus arc volcanoes, with volcanoes in Hawaii and Iceland outgassing large fluxes of gaseous and particulate chalcophiles; and arc volcanoes' plumes, in contrast, enriched in Zn, Cu, Tl and Pb. Metals and metalloids partition into a magmatic vapor phase from silicate melt at crustal pressures. Their abundance in magmatic vapor is influenced strongly by sulfide saturation and by the composition of the magmatic vapor phase, particularly with respect to chloride. These factors are highly dependent on tectonic setting. Metal outgassing is controlled by magma water content and redox: deep saturation in vapor and minimal sulfide in arc basalts yields metal-rich vapor; shallow degassing and resorption of sulfides feeds the metal content of volcanic gas in ocean islands. We present a detailed study of the sulfide systematics of the products of the 2014-2015 Holuhraun basaltic fissure eruption (Bárðarbunga volcanic system, Iceland) to illustrate the interplay between late water and sulfur outgassing; sulfide saturation and breakdown; and metal partitioning into a vapor phase. Sulfide globules, representing quenched droplets of an immiscible sulfide liquid, are preserved within erupted tephra. Sulfide globules in rapidly quenched tephra are preserved within both matrix glass and as inclusions in crystals. The stereologically-corrected 3D size distribution of sulfide globules ranges from importance in supplying sulfur and metals to the atmosphere during eruption.

Formation of mercury sulfide from Hg(II)−thiolate complexes in natural organic matter

Science.gov (United States)

Alain Manceau,; Cyprien Lemouchi,; Mironel Enescu,; Anne-Claire Gaillot,; Martine Lanson,; Valerie Magnin,; Pieter Glatzel,; Poulin, Brett; Ryan, Joseph N.; Aiken, George R.; Isabelle Gautier-Lunea,; Kathryn L. Nagy,

2015-01-01

Methylmercury is the environmental form of neurotoxic mercury that is biomagnified in the food chain. Methylation rates are reduced when the metal is sequestered in crystalline mercury sulfides or bound to thiol groups in macromolecular natural organic matter. Mercury sulfide minerals are known to nucleate in anoxic zones, by reaction of the thiol-bound mercury with biogenic sulfide, but not in oxic environments. We present experimental evidence that mercury sulfide forms from thiol-bound mercury alone in aqueous dark systems in contact with air. The maximum amount of nanoparticulate mercury sulfide relative to thiol-bound mercury obtained by reacting dissolved mercury and soil organic matter matches that detected in the organic horizon of a contaminated soil situated downstream from Oak Ridge, TN, in the United States. The nearly identical ratios of the two forms of mercury in field and experimental systems suggest a common reaction mechanism for nucleating the mineral. We identified a chemical reaction mechanism that is thermodynamically favorable in which thiol-bound mercury polymerizes to mercury–sulfur clusters. The clusters form by elimination of sulfur from the thiol complexes via breaking of mercury–sulfur bonds as in an alkylation reaction. Addition of sulfide is not required. This nucleation mechanism provides one explanation for how mercury may be immobilized, and eventually sequestered, in oxygenated surface environments.

Platinum-group elements and gold in base metal sulfides, platinum-group minerals, and Re-Os isotope compositions of the Uitkomst complex, South Africa

Czech Academy of Sciences Publication Activity Database

Trubač, Jakub; Ackerman, Lukáš; Gauert, Ch.; Ďurišová, Jana; Hrstka, Tomáš

2018-01-01

Roč. 113, č. 2 (2018), s. 439-461 ISSN 0361-0128 R&D Projects: GA ČR GA13-15390S Institutional support: RVO:67985831 Keywords : binary alloys * copper compounds * economic geology * gold * iridium * isotopes * ore deposits * osmium * palladium * platinum * platinum metals * pyrites * Rhenium * rhenium alloys * ruthenium * solid solutions * sulfur compounds * crustal materials * mass-balance calculations * massive sulfides * mineralized zone * monosulfide solid solutions * platinum group elements * platinum group elements (PGEs) * platinum group minerals Subject RIV: DB - Geology ; Mineralogy; AC - Archeology, Anthropology, Ethnology (ARUB-Q) OBOR OECD: Geology; Archaeology (ARUB-Q) Impact factor: 2.519, year: 2016

Studies on ternary silver sulfides; Fukugo gin ryukabutsu ni kansuru kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-10-31

Some sulfides containing silver show high ion mobility based on movability of silver, whose application is expected. Studies have been carried out centrally on synthesis of new compounds of ternary silver sulfides by elucidating the relationship among their compositions, structures and properties by means of crystal chemical studies mainly on their phase relationship. A few new compounds have been synthesized, such as the ones having the argyrodite family compound structure including transition metals. The synthesizing process takes a kind of turbulent liquid state structure at elevated temperatures because of movability of silver, but silver is fixed at low temperatures in different sites between skeleton structures made by other atoms. These studies on phase transfer, structures, and silver movability have been based on X-ray diffraction, infrared and Raman spectroscopic measurements, NMR, measurements of electric and thermal characteristics. For the studies related to compositions and structures of ternary metal sulfides which take compound crystalline structure, a structure analyzing method based on multi-dimensional hyperspatial groups was used. This paper reports the summary of the studies in seven chapters, and dwells on the remaining problems and future prospects. 158 refs., 114 figs., 65 tabs.

Pyritization processes and greigite formation in the advancing sulfidization front in the Upper Pleistocene sediments of the Black Sea

DEFF Research Database (Denmark)

Neretin, LN; Bottcher, ME; Jørgensen, BB

2004-01-01

Pyritization in late Pleistocene sediments of the Black Sea is driven by sulfide formed during anaerobic methane oxidation. A sulfidization front is formed by the opposing gradients of sulfide and dissolved iron. The sulfidization processes are controlled by the diffusion flux of sulfide from above...... and by the solid reactive iron content. Two processes of diffusion-limited pyrite formation were identified. The first process includes pyrite precipitation with the accumulation of iron sulfide precursors with the average chemical composition of FeSn (n = 1.10-1.29), including greigite. Elemental sulfur...... and polysulfides, formed from H,S by a reductive dissolution of Fe(Ill)-containing minerals, serve as intermediates to convert iron sulfides into pyrite. In the second process, a "direct" pyrite precipitation occurs through prolonged exposure of iron-containing minerals to dissolved sulfide. Methane-driven sulfate...

Kinetics of Indigenous Nitrate Reducing Sulfide Oxidizing Activity in Microaerophilic Wastewater Biofilms

Science.gov (United States)

Villahermosa, Desirée; Corzo, Alfonso; Garcia-Robledo, Emilio; González, Juan M.; Papaspyrou, Sokratis

2016-01-01

Nitrate decreases sulfide release in wastewater treatment plants (WWTP), but little is known on how it affects the microzonation and kinetics of related microbial processes within the biofilm. The effect of nitrate addition on these properties for sulfate reduction, sulfide oxidation, and oxygen respiration were studied with the use of microelectrodes in microaerophilic wastewater biofilms. Mass balance calaculations and community composition analysis were also performed. At basal WWTP conditions, the biofilm presented a double-layer system. The upper microaerophilic layer (~300 μm) showed low sulfide production (0.31 μmol cm-3 h-1) and oxygen consumption rates (0.01 μmol cm-3 h-1). The anoxic lower layer showed high sulfide production (2.7 μmol cm-3 h-1). Nitrate addition decreased net sulfide production rates, caused by an increase in sulfide oxidation rates (SOR) in the upper layer, rather than an inhibition of sulfate reducing bacteria (SRB). This suggests that the indigenous nitrate reducing-sulfide oxidizing bacteria (NR-SOB) were immediately activated by nitrate. The functional vertical structure of the biofilm changed to a triple-layer system, where the previously upper sulfide-producing layer in the absence of nitrate split into two new layers: 1) an upper sulfide-consuming layer, whose thickness is probably determined by the nitrate penetration depth within the biofilm, and 2) a middle layer producing sulfide at an even higher rate than in the absence of nitrate in some cases. Below these layers, the lower net sulfide-producing layer remained unaffected. Net SOR varied from 0.05 to 0.72 μmol cm-3 h-1 depending on nitrate and sulfate availability. Addition of low nitrate concentrations likely increased sulfate availability within the biofilm and resulted in an increase of both net sulfate reduction and net sulfide oxidation by overcoming sulfate diffusional limitation from the water phase and the strong coupling between SRB and NR-SOB syntrophic

Kinetics of Indigenous Nitrate Reducing Sulfide Oxidizing Activity in Microaerophilic Wastewater Biofilms.

Directory of Open Access Journals (Sweden)

Desirée Villahermosa

Full Text Available Nitrate decreases sulfide release in wastewater treatment plants (WWTP, but little is known on how it affects the microzonation and kinetics of related microbial processes within the biofilm. The effect of nitrate addition on these properties for sulfate reduction, sulfide oxidation, and oxygen respiration were studied with the use of microelectrodes in microaerophilic wastewater biofilms. Mass balance calaculations and community composition analysis were also performed. At basal WWTP conditions, the biofilm presented a double-layer system. The upper microaerophilic layer (~300 μm showed low sulfide production (0.31 μmol cm-3 h-1 and oxygen consumption rates (0.01 μmol cm-3 h-1. The anoxic lower layer showed high sulfide production (2.7 μmol cm-3 h-1. Nitrate addition decreased net sulfide production rates, caused by an increase in sulfide oxidation rates (SOR in the upper layer, rather than an inhibition of sulfate reducing bacteria (SRB. This suggests that the indigenous nitrate reducing-sulfide oxidizing bacteria (NR-SOB were immediately activated by nitrate. The functional vertical structure of the biofilm changed to a triple-layer system, where the previously upper sulfide-producing layer in the absence of nitrate split into two new layers: 1 an upper sulfide-consuming layer, whose thickness is probably determined by the nitrate penetration depth within the biofilm, and 2 a middle layer producing sulfide at an even higher rate than in the absence of nitrate in some cases. Below these layers, the lower net sulfide-producing layer remained unaffected. Net SOR varied from 0.05 to 0.72 μmol cm-3 h-1 depending on nitrate and sulfate availability. Addition of low nitrate concentrations likely increased sulfate availability within the biofilm and resulted in an increase of both net sulfate reduction and net sulfide oxidation by overcoming sulfate diffusional limitation from the water phase and the strong coupling between SRB and NR

SULFIDE MINERALS IN SEDIMENTS

Science.gov (United States)

The formation processes of metal sulfides in sediments, especially iron sulfides, have been the subjects of intense scientific research because of linkages to the global biogeochemical cycles of iron, sulfur, carbon, and oxygen. Transition metal sulfides (e.g., NiS, CuS, ZnS, Cd...

Carbon-supported iron and iron-molybdenum sulfide catalysts

International Nuclear Information System (INIS)

Ramselaar, W.L.T.M.

1988-01-01

The main objective was to describe the relations between the characteristics (composition and dispersion) of the actual sulfide phase and the catalytic activity. Attention was also paid to the influence of preparational aspects on these characteristics. The catalysts were characterized using in-situ Moessbauer spectroscopy down to 2.0 K. 254 refs.; 47 figs.; 22 tabs

Method for Forming Fiber Reinforced Composite Bodies with Graded Composition and Stress Zones

Science.gov (United States)

Singh, Mrityunjay (Inventor); Levine, Stanley R. (Inventor); Smialek, James A. (Inventor)

1999-01-01

A near-net, complex shaped ceramic fiber reinforced silicon carbide based composite bodies with graded compositions and stress zones is disclosed. To provide the composite a fiber preform is first fabricated and an interphase is applied by chemical vapor infiltration, sol-gel or polymer processes. This first body is further infiltrated with a polymer mixture containing carbon, and/or silicon carbide, and additional oxide, carbide, or nitride phases forming a second body. One side of the second body is spray coated or infiltrated with slurries containing high thermal expansion and oxidation resistant. crack sealant phases and the other side of this second body is coated with low expansion phase materials to form a third body. This third body consisting of porous carbonaceous matrix surrounding the previously applied interphase materials, is then infiltrated with molten silicon or molten silicon-refractory metal alloys to form a fourth body. The resulting fourth body comprises dense composites consisting of fibers with the desired interphase which are surrounded by silicon carbide and other second phases materials at the outer and inner surfaces comprising material of silicon, germanium, refractory metal suicides, borides, carbides, oxides, and combinations thereof The resulting composite fourth body has different compositional patterns from one side to the other.

Synthesis of bacteria promoted reduced graphene oxide-nickel sulfide networks for advanced supercapacitors.

Science.gov (United States)

Zhang, Haiming; Yu, Xinzhi; Guo, Di; Qu, Baihua; Zhang, Ming; Li, Qiuhong; Wang, Taihong

2013-08-14

Supercapacitors with potential high power are useful and have attracted much attention recently. Graphene-based composites have been demonstrated to be promising electrode materials for supercapacitors with enhanced properties. To improve the performance of graphene-based composites further and realize their synthesis with large scale, we report a green approach to synthesize bacteria-reduced graphene oxide-nickel sulfide (BGNS) networks. By using Bacillus subtilis as spacers, we deposited reduced graphene oxide/Ni3S2 nanoparticle composites with submillimeter pores directly onto substrate by a binder-free electrostatic spray approach to form BGNS networks. Their electrochemical capacitor performance was evaluated. Compared with stacked reduced graphene oxide-nickel sulfide (GNS) prepared without the aid of bacteria, BGNS with unique nm-μm structure exhibited a higher specific capacitance of about 1424 F g(-1) at a current density of 0.75 A g(-1). About 67.5% of the capacitance was retained as the current density increased from 0.75 to 15 A g(-1). At a current density of 75 A g(-1), a specific capacitance of 406 F g(-1) could still remain. The results indicate that the reduced graphene oxide-nickel sulfide network promoted by bacteria is a promising electrode material for supercapacitors.

Solvent transfer of graphene oxide for synthesis of tin mono-sulfide graphene composite and application as anode of lithium-ion battery

Energy Technology Data Exchange (ETDEWEB)

Tripathi, Alok M., E-mail: alokmani@iitb.ac.in; Mitra, Sagar

2016-11-15

Graphical abstract: Destabilization of graphene oxide colloid and SnS graphene composite preparation for lithium-ion battery. - Abstract: Tin mono sulfide (SnS) graphene composite has been synthesized for anode of lithium-ion battery. For synthesis of composite, graphene oxide (GO)-water (H{sub 2}O) colloid has been destabilized and ensured the complete transfer of graphene oxide into another organic solvent N, N-dimethyl formamide (DMF). Mechanism for the destabilization of GO-H{sub 2}O colloid is established. Surface to surface attachment of SnS on graphene sheet is achieved by solvothermal solution phase assembly of graphene sheets and SnS nanoparticles in DMF solvent. Graphene plays role in nanoparticle formation in composite. Such confined composite has been cycled reversibly at current rate of 160 mA g{sup −1}, in voltage region of 0.01–2.5 V and exhibit a superior discharge capacity of 630 mAh g{sup −1} after 50th cycle. Ex situ TEM analysis of used electrode reveal that the SnS nanoparticle-graphene composite with CMC binder perform better due to proper shape retention of electroactive materials during electrochemical cycling.

Solvent transfer of graphene oxide for synthesis of tin mono-sulfide graphene composite and application as anode of lithium-ion battery

International Nuclear Information System (INIS)

Tripathi, Alok M.; Mitra, Sagar

2016-01-01

Graphical abstract: Destabilization of graphene oxide colloid and SnS graphene composite preparation for lithium-ion battery. - Abstract: Tin mono sulfide (SnS) graphene composite has been synthesized for anode of lithium-ion battery. For synthesis of composite, graphene oxide (GO)-water (H_2O) colloid has been destabilized and ensured the complete transfer of graphene oxide into another organic solvent N, N-dimethyl formamide (DMF). Mechanism for the destabilization of GO-H_2O colloid is established. Surface to surface attachment of SnS on graphene sheet is achieved by solvothermal solution phase assembly of graphene sheets and SnS nanoparticles in DMF solvent. Graphene plays role in nanoparticle formation in composite. Such confined composite has been cycled reversibly at current rate of 160 mA g"−"1, in voltage region of 0.01–2.5 V and exhibit a superior discharge capacity of 630 mAh g"−"1 after 50th cycle. Ex situ TEM analysis of used electrode reveal that the SnS nanoparticle-graphene composite with CMC binder perform better due to proper shape retention of electroactive materials during electrochemical cycling.

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.

High-Resolution P'P' Precursor Imaging of Nazca-South America Plate Boundary Zones and Inferences for Transition Zone Temperature and Composition

Science.gov (United States)

Gu, Y. J.; Schultz, R.

2013-12-01

Knowledge of upper mantle transition zone stratification and composition is highly dependent on our ability to efficiently extract and properly interpret small seismic arrivals. A promising high-frequency seismic phase group particularly suitable for a global analysis is P'P' precursors, which are capable of resolving mantle structures at vertical and lateral resolution of approximately 5 and 200 km, respectively, owing to their shallow incidence angle and small, quasi-symmetric Fresnel zones. This study presents a simultaneous analysis of SS and P'P' precursors based on deconvolution, Radon transform and depth migration. Our multi-resolution survey of the mantle near Nazca-South America subduction zone reveals both olivine and garnet related transitions at depth below 400 km. We attribute a depressed 660 to thermal variations, whereas compositional variations atop the upper-mantle transition zone are needed to explain the diminished or highly complex reflected/scattered signals from the 410 km discontinuity. We also observe prominent P'P' reflections within the transition zone, especially near the plate boundary zone where anomalously high reflection amplitudes result from a sharp (~10 km thick) mineral phase change resonant with the dominant frequency of the P'P' precursors. Near the base of the upper mantle, the migration of SS precursors shows no evidence of split reflections near the 660-km discontinuity, but potential majorite-ilmenite (590-640 km) and ilmenite-perovskite transitions (740-750 km) are identified based on similarly processed high-frequency P'P' precursors. At nominal mantle temperatures these two phase changes may be seismically indistinguishable, but colder mantle conditions from the descending Nazca plate, the presence of water and variable Fe contents may cause sufficient separation for a reliable analysis. In addition, our preliminary results provide compelling evidence for multiple shallow lower-mantle reflections (at ~800 km) along the

Three-dimensional imaging of a complex concaved cuboctahedron copper sulfide crystal by x-ray nanotomography

International Nuclear Information System (INIS)

Chen Jie; Tian Jinping; Li Wenjie; Tian Yangchao; Wu Chunyan; Yu Shuhong

2008-01-01

By combining Fresnel zone-plate based transmission x-ray microscopy with computed tomography, the nanoscale features in materials with complex shapes can be imaged using synchrotron radiation. The tomographic data sets of a complex copper sulfide crystal were acquired in the angle range ±70 deg. at photon energy of 8.0 keV and then were reconstructed by a standard filtered-back-projection algorithm. This experiment shows the quantifiable three-dimensional information of the copper sulfide crystal, which offers a complete understanding of the concaved cuboctahedron structure with 14 faces comprising of six squares and eight triangles

Hydrogen sulfide waste treatment by microwave plasma-chemistry

Energy Technology Data Exchange (ETDEWEB)

Harkness, J.B.L.; Doctor, R.D.

1994-03-01

A waste-treatment process that recovers both hydrogen and sulfur from industrial acid-gas waste streams is being developed to replace the Claus technology, which recovers only sulfur. The proposed process is derived from research reported in the Soviet technical literature and uses microwave (or radio-frequency) energy to initiate plasma-chemical reactions that dissociate hydrogen sulfide into elemental hydrogen and sulfur. This process has several advantages over the current Claus-plus-tail-gas-cleanup technology, which burns the hydrogen to water. The primary advantage of the proposal process is its potential for recovering and recycling hydrogen more cheaply than the direct production of hydrogen. Since unconverted hydrogen sulfide is recycled to the plasma reactor, the plasma-chemical process has the potential for sulfur recoveries in excess of 99% without the additional complexity of the tail-gas-cleanup processes associated with the Claus technology. There may also be some environmental advantages to the plasma-chemical process, because the process purge stream would primarily be the carbon dioxide and water contained in the acid-gas waste stream. Laboratory experiments with pure hydrogen sulfide have demonstrated the ability of the process to operate at or above atmospheric pressure with an acceptable hydrogen sulfide dissociation energy. Experiments with a wide range of acid-gas compositions have demonstrated that carbon dioxide and water are compatible with the plasma-chemical dissociation process and that they do not appear to create new waste-treatment problems. However, carbon dioxide does have negative impacts on the overall process. First, it decreases the hydrogen production, and second, it increases the hydrogen sulfide dissociation energy.

Immiscibility of Fluid Phases at Magmatic-hydrothermal Transition: Formation of Various PGE-sulfide Mineralization for Layered Basic Intrusions

Science.gov (United States)

Zhitova, L.; Borisenko, A.; Morgunov, K.; Zhukova, I.

2007-12-01

Fluid inclusions in quartz of the Merensky Reef (Bushveld Complex, South Africa) and the Chineisky Pluton (Transbaikal Region, Russia) were studied using cryometry, microthermometry, Raman-spectroscopy, LA ICP- MS, scanning electronic microscopy, gas-chromatography and isotopic methods. This allowed us to document some examples of fluid phase separation resulting in formation of different types of PGE-sulfide mineralization for layered basic intrusions. The results obtained show at least three generations of fluid separated from boiling residual alumosilicate intercumulus liquid of the Merensky Reef. The earliest fluid phase composed of homogenous high-dense methane and nitrogen gas mixture was identified in primary gas and co-existing anomalous fluid inclusions from symplectitic quartz. The next generation, heterophase fluid, composed of brines containing a free low-dense (mostly of carbon dioxide) gas phase, was observed in primary multiphase and coexisting gas-rich inclusions of miarolitic quartz crystals. The latest generation was also a heterophase fluid (low salinity water-salt solution and free low-dense methane gas phase) found in primary water-salt and syngenetic gas inclusions from peripheral zones of miarolitic quartz crystals. For the Chineisky Pluton reduced endocontact magmatogene fluids changed to oxidized low salinity hydrothermal fluids in exocontact zone. This resulted in formation of sulfide-PGE enrichment marginal zones of intrusion. The results obtained give us a possibility to suggest that: 1) Fluid phase separation is a typical feature of magmatogene fluids for layered basic intrusions. 2) Reduced fluids can extract and transport substantial PGE and sulfide concentrations. 3) Oxidation of reduced fluids is one of the most important geochemical barriers causing abundant PGE minerals and sulfides precipitation. This in turn results in both formation of PGE reefs or enriched contact zones of layered basic intrusions. This work was supported by

Change of sulfide inclusions in steel microalloying with rare earth and alkaline-earth elements

International Nuclear Information System (INIS)

Averin, V.V.; Polonskaya, S.M.; Chistyakov, V.F.

1977-01-01

The conditions for the formation of sulfides in molten and solid iron were determined by considering the thermodynamics of the interaction of sulfur and of oxygen with various components. It was shown in casting of low-carbon steel under a blanket of slag-forming briquettes, calcium of the silicocalcium partly passes to iron and to the sulfide phase. The sulfide inclusions with calcium in rolling become lens-shaped and acquire a greater strength, proportional to the content of calcium, thus ensuring a lesser anisotropy of steel. The change in the shape and the composition of sulfide inclusions effects the fracture of the metal which changes in type from separation along lamellar inclusions to a plastic fracture, i.e., enhances resilience. It is thus noted that rare-earth and alkali-earth elements, in particular, cerium and calcium are promising agents for desulfurating molten iron

Sulfur isotope study of a modern intertidal environment, and the interpretation of ancient sulfides

International Nuclear Information System (INIS)

Chambers, L.A.

1982-01-01

Extensive sulfur isotope distribution data for sulfides precipitated in an intertidal environment show no distinctive features when compared with isotope values for other marine, sedimentary sulfides. The fractionation ranges from α = 1.030 to α = 1.048. The pattern is characteristic for a system essentially open to sulfate, and isotope analyses of interstitial sulfates are corroborative. A population of sulfate-reducing bacteria of the order of 10 9 organisms per cc of interstitial water is indicated. Seasonal variation of the isotope distribution reflects a transient sulfide composition and a bacterial population in which the fractionation effect is indirectly controlled by temperature. The data presented for this modern shallow water environment are at variance with an earlier assessment of isotopic distributions in ancient sulfides which linked shallow water environments with limited fractionation (α =< 1.025) in a closed system. (author)

Sulfur isotope study of a modern intertidal environment, and the interpretation of ancient sulfides

Energy Technology Data Exchange (ETDEWEB)

Chambers, L.A. (Baas Becking Geobiological Lab., Canberra City (Australia))

1982-05-01

Extensive sulfur isotope distribution data for sulfides precipitated in an intertidal environment show no distinctive features when compared with isotope values for other marine, sedimentary sulfides. The fractionation ranges from ..cap alpha.. = 1.030 to ..cap alpha.. = 1.048. The pattern is characteristic for a system essentially open to sulfate, and isotope analyses of interstitial sulfates are corroborative. A population of sulfate-reducing bacteria of the order of 10/sup 9/ organisms per cc of interstitial water is indicated. Seasonal variation of the isotope distribution reflects a transient sulfide composition and a bacterial population in which the fractionation effect is indirectly controlled by temperature. The data presented for this modern shallow water environment are at variance with an earlier assessment of isotopic distributions in ancient sulfides which linked shallow water environments with limited fractionation (..cap alpha.. =< 1.025) in a closed system.

Replacive sulfide formation in anhydrite chimneys from the Pacmanus hydrothermal field, Papua New Guinea

Science.gov (United States)

Los, Catharina; Bach, Wolfgang; Plümper, Oliver

2016-04-01

Hydrothermal flow within the oceanic crust is an important process for the exchange of energy and mass between the lithosphere, hydrosphere and biosphere. Infiltrated seawater heats up and interacts with wall rock, causing mineral replacement reactions. These play a large role in the formation of ore deposits; at the discharge zone, a hot, acidic and metal-rich potential ore fluid exits the crust. It mixes with seawater and forms chimneys, built up of sulfate minerals such as anhydrite (CaSO4), which are subsequently replaced by sulfide minerals. Sulfide formation is related to fluid pathways, defined by cracks and pores in the sulfate chimney. Over time, these systems might develop into massive sulfide deposits. The big question is then: how is sulfate-sulfide replacement related to the evolution of rock porosity? To address this question, sulfide-bearing anhydrite chimneys from the Pacmanus hydrothermal field (Manus Basin, Papua New Guinea) were studied using X-ray tomography, EMPA, FIB-SEM and -TEM. The apparently massive anhydrite turns out highly porous on the micro scale, with sulfide minerals in anhydrite cleavage planes and along grain boundaries. The size of the sulfide grains relates to the pores they grew into, suggesting a tight coupling between dissolution (porosity generation) and growth of replacive minerals. Some of the sulfide grains are hollow and apparently used the dissolving anhydrite as a substrate to start growth in a pore. Another mode of sulfide development is aggregates of euhedral pyrite cores surrounded by colloform chalcopyrite. This occurrence implies that fluid pathways have remained open for some time to allow several stages of precipitation during fluid evolution. To start the replacement and to keep it going, porosity generation is crucial. Our samples show that dissolution of anhydrite occurred along pathways where fluid could enter, such as cleavage planes and grain boundaries. It appears that fluids ascending within the inner

Nanostructured metal sulfides for energy storage

Science.gov (United States)

Rui, Xianhong; Tan, Huiteng; Yan, Qingyu

2014-08-01

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.

Evidence for a sulfur-undersaturated lunar interior from the solubility of sulfur in lunar melts and sulfide-silicate partitioning of siderophile elements

Science.gov (United States)

Steenstra, E. S.; Seegers, A. X.; Eising, J.; Tomassen, B. G. J.; Webers, F. P. F.; Berndt, J.; Klemme, S.; Matveev, S.; van Westrenen, W.

2018-06-01

Sulfur concentrations at sulfide saturation (SCSS) were determined for a range of low- to high-Ti lunar melt compositions (synthetic equivalents of Apollo 14 black and yellow glass, Apollo 15 green glass, Apollo 17 orange glass and a late-stage lunar magma ocean melt, containing between 0.2 and 25 wt.% TiO2) as a function of pressure (1-2.5 GPa) and temperature (1683-1883 K). For the same experiments, sulfide-silicate partition coefficients were derived for elements V, Cr, Mn, Co, Cu, Zn, Ga, Ge, As, Se, Mo, Sn, Sb, Te, W and Pb. The SCSS is a strong function of silicate melt composition, most notably FeO content. An increase in temperature increases the SCSS and an increase in pressure decreases the SCSS, both in agreement with previous work on terrestrial, lunar and martian compositions. Previously reported SCSS values for high-FeO melts were combined with the experimental data reported here to obtain a new predictive equation to calculate the SCSS for high-FeO lunar melt compositions. Calculated SCSS values, combined with previously estimated S contents of lunar low-Ti basalts and primitive pyroclastic glasses, suggest their source regions were not sulfide saturated. Even when correcting for the currently inferred maximum extent of S degassing during or after eruption, sample S abundances are still > 700 ppm lower than the calculated SCSS values for these compositions. To achieve sulfide saturation in the source regions of low-Ti basalts and lunar pyroclastic glasses, the extent of degassing of S in lunar magma would have to be orders of magnitude higher than currently thought, inconsistent with S isotopic and core-to-rim S diffusion profile data. The only lunar samples that could have experienced sulfide saturation are some of the more evolved A17 high-Ti basalts, if sulfides are Ni- and/or Cu rich. Sulfide saturation in the source regions of lunar melts is also inconsistent with the sulfide-silicate partitioning systematics of Ni, Co and Cu. Segregation of

Poly(methyl methacrylate)/layered zinc sulfide nanocomposites: Preparation, characterization and the improvements in thermal stability, flame retardant and optical properties

Energy Technology Data Exchange (ETDEWEB)

Wang, Biao; Zhou, Keqing; Jiang, Saihua [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); Shi, Yongqian [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, 166 Ren’ai Road, Suzhou, Jiangsu 215123 (China); Wang, Bibo [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); Gui, Zhou, E-mail: zgui@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); Hu, Yuan, E-mail: yuanhu@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, 166 Ren’ai Road, Suzhou, Jiangsu 215123 (China)

2014-08-15

Highlights: • Layered zinc sulfide (LZnS) was synthesized successfully via hydrothermal method. • We prepare PMMA/LZnS nanocomposites by in situ bulk polymerization of MMA. • PMMA/LZnS nanocomposites were investigated by TGA, DSC, MCC, UV–vis and PL test. • The thermal stability, flame retardant and optical properties of PMMA are improved. - Abstract: Layered zinc sulfide (LZnS) was synthesized successfully via hydrothermal method and poly(methyl methacrylate) (PMMA)/layered zinc sulfide nanocomposites were obtained by in situ bulk polymerization of methyl methacrylate (MMA). X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the as-synthesized layered zinc sulfide and PMMA/layered zinc sulfide nanocomposites. Microscale combustion calorimeter (MCC), differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA) were used to test the thermal properties of the composites. Ultraviolet visible (UV–vis) transmittance spectra and photoluminence (PL) spectra were obtained to investigate the optical properties of the composites. From the results, the thermal degradation temperature is increased by 20–50 °C, the peak of heat release rate (pHRR) and total heat release (THR) are both decreased by above 30%, and the photoluminence intensity is enhanced with the increasing loading of layered zinc sulfide.

Poly(methyl methacrylate)/layered zinc sulfide nanocomposites: Preparation, characterization and the improvements in thermal stability, flame retardant and optical properties

International Nuclear Information System (INIS)

Wang, Biao; Zhou, Keqing; Jiang, Saihua; Shi, Yongqian; Wang, Bibo; Gui, Zhou; Hu, Yuan

2014-01-01

Highlights: • Layered zinc sulfide (LZnS) was synthesized successfully via hydrothermal method. • We prepare PMMA/LZnS nanocomposites by in situ bulk polymerization of MMA. • PMMA/LZnS nanocomposites were investigated by TGA, DSC, MCC, UV–vis and PL test. • The thermal stability, flame retardant and optical properties of PMMA are improved. - Abstract: Layered zinc sulfide (LZnS) was synthesized successfully via hydrothermal method and poly(methyl methacrylate) (PMMA)/layered zinc sulfide nanocomposites were obtained by in situ bulk polymerization of methyl methacrylate (MMA). X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the as-synthesized layered zinc sulfide and PMMA/layered zinc sulfide nanocomposites. Microscale combustion calorimeter (MCC), differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA) were used to test the thermal properties of the composites. Ultraviolet visible (UV–vis) transmittance spectra and photoluminence (PL) spectra were obtained to investigate the optical properties of the composites. From the results, the thermal degradation temperature is increased by 20–50 °C, the peak of heat release rate (pHRR) and total heat release (THR) are both decreased by above 30%, and the photoluminence intensity is enhanced with the increasing loading of layered zinc sulfide

Purification of hydrogen sulfide

International Nuclear Information System (INIS)

Tsao, U.

1978-01-01

A process is described for purifying a hydrogen sulfide gas stream containing carbon dioxide, comprising (a) passing the gas stream through a bed of solid hydrated lime to form calcium hydrosulfide and calcium carbonate and (b) regenerating hydrogen sulfide from said calcium hydrosulfide by reacting the calcium hydrosulfide with additional carbon dioxide. The process is especially applicable for use in a heavy water recovery process wherein deuterium is concentrated from a feed water containing carbon dioxide by absorption and stripping using hydrogen sulfide as a circulating medium, and the hydrogen sulfide absorbs a small quantity of carbon dioxide along with deuterium in each circulation

Nanoparticles of noble metals in the supergene zone

Science.gov (United States)

Zhmodik, S. M.; Kalinin, Yu. A.; Roslyakov, N. A.; Mironov, A. G.; Mikhlin, Yu. L.; Belyanin, D. K.; Nemirovskaya, N. A.; Spiridonov, A. M.; Nesterenko, G. V.; Airiyants, E. V.; Moroz, T. N.; Bul'bak, T. A.

2012-04-01

Formation of noble metal nanoparticles is related to various geological processes in the supergene zone. Dispersed mineral phases appear during weathering of rocks with active participation of microorganisms, formation of soil, in aqueous medium and atmosphere. Invisible gold and other noble metals are incorporated into oxides, hydroxides, and sulfides, as well as in dispersed organic and inorganic carbonic matter. Sulfide minerals that occur in bedrocks and ores unaltered by exogenic processes and in cementation zone are among the main concentrators of noble metal nanoparticles. The ability of gold particles to disaggregate is well-known and creates problems in technological and analytical practice. When Au and PGE nanoparticles and clusters occur, these problems are augmented because of their unusual reactions and physicochemical properties. The studied gold, magnetite, titanomagnetite and pyrite microspherules from cementation zone and clay minerals of laterites in Republic of Guinea widen the knowledge of their abundance and inferred formation conditions, in particular, in the contemporary supergene zone. Morphology and composition of micrometer-sized Au mineral spherules were studied with SEM and laser microprobe. The newly formed segregations of secondary gold on the surface of its residual grains were also an object of investigation. The character of such overgrowths is the most indicative for nanoparticles. The newly formed Au particles provide evidence for redistribution of ultradispersed gold during weathering. There are serious prerequisites to state that microorganisms substantially control unusual nano-sized microspherical morphology of gold particles in the supergene zone. This is supported by experiments indicating active absorption of gold by microorganisms and direct evidence for participation of Ralstonia metallidurans bacteria in the formation of peculiar corroded bacteriomorphic surface of gold grains. In addition, the areas enriched in carbon

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...... higher hydrogen sulfide uptake followed by oxidation catalyzed by iron-containing enzymes such as cytochrome c oxidase in a process uncoupled from energy conservation....

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...... higher hydrogen sulfide uptake followed by oxidation catalyzed by iron-containing enzymes such as cytochrome c oxidase in a process uncoupled from energy conservation....

A REVIEW OF THE MEASUREMENT AND DEVELOPMENT OF CRYSTALLINITY AND ITS RELATION TO PROPERTIES IN NEAT POLY(PHENYLENE SULFIDE) AND ITS FIBER REINFORCED COMPOSITES

Energy Technology Data Exchange (ETDEWEB)

Spruiell, J.E.

2005-01-31

This literature review paper was prepared for the Department of Energy Automotive Lightweighting Program to address materials interest expressed by the Automotive Composites Consortium and it summarizes the measurement and development of crystallinity and its relation to properties in poly(phenylene sulfide) (PPS) and its fiber reinforced composites. The objective of this effort was to broaden the understanding of low-cost, semi-crystalline thermoplastic resins and composites for use in potential future automotive applications. PPS has an excellent combination of attributes including good mechanical properties and thermal stability, high chemical resistance, low moisture absorption, good weathering resistance, high dimensional stability, low flammability, and excellent processability. Specific areas addressed in this report include: Structure of PPS; Techniques for measuring crystallinity; Crystallinity as a function of prior treatment; Crystallization kinetics and morphology; Effect of variation of crystallinity on properties of PPS and its composites; Environmental stability; Unusual effects of cooling rates and degree of crystallinity on mechanical properties of AS4/PPS composites; Recent PPS laminate data (Ten Cate Advanced Composites); and Recommendations for future research.

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

Alternative waste residue materials for passive in situ prevention of sulfide-mine tailings oxidation: a field evaluation.

Science.gov (United States)

Nason, Peter; Johnson, Raymond H; Neuschütz, Clara; Alakangas, Lena; Öhlander, Björn

2014-02-28

Novel solutions for sulfide-mine tailings remediation were evaluated in field-scale experiments on a former tailings repository in northern Sweden. Uncovered sulfide-tailings were compared to sewage-sludge biosolid amended tailings over 2 years. An application of a 0.2m single-layer sewage-sludge amendment was unsuccessful at preventing oxygen ingress to underlying tailings. It merely slowed the sulfide-oxidation rate by 20%. In addition, sludge-derived metals (Cu, Ni, Fe, and Zn) migrated and precipitated at the tailings-to-sludge interface. By using an additional 0.6m thick fly-ash sealing layer underlying the sewage sludge layer, a solution to mitigate oxygen transport to the underlying tailings and minimize sulfide-oxidation was found. The fly-ash acted as a hardened physical barrier that prevented oxygen diffusion and provided a trap for sludge-borne metals. Nevertheless, the biosolid application hampered the application, despite the advances in the effectiveness of the fly-ash layer, as sludge-borne nitrate leached through the cover system into the underlying tailings, oxidizing pyrite. This created a 0.3m deep oxidized zone in 6-years. This study highlights that using sewage sludge in unconventional cover systems is not always a practical solution for the remediation of sulfide-bearing mine tailings to mitigate against sulfide weathering and acid rock drainage formation. Copyright © 2014 Elsevier B.V. All rights reserved.

Propagation of normal zones in composite superconductors

International Nuclear Information System (INIS)

Dresner, L.

1976-08-01

This paper describes calculations of propagation velocities of normal zones in composite superconductors. Full accounting is made for (1) current sharing, (2) the variation with temperature of the thermal conductivity of the copper matrix, and the specific heats of the matrix and the superconductor, and (3) the variation with temperature of the steady-state heat transfer at a copper-helium interface in the nucleate-boiling, transition, and film-boiling ranges. The theory, which contains no adjustable parameters, is compared with experiments on bare (uninsulated) conductors. Agreement is not good. It is concluded that the effects of transient heat transfer may need to be included in the theory to improve agreement with experiment

Quantitative microbial community analysis of three different sulfidic mine tailing dumps generating acid mine drainage.

Science.gov (United States)

Kock, Dagmar; Schippers, Axel

2008-08-01

The microbial communities of three different sulfidic and acidic mine waste tailing dumps located in Botswana, Germany, and Sweden were quantitatively analyzed using quantitative real-time PCR (Q-PCR), fluorescence in situ hybridization (FISH), catalyzed reporter deposition-FISH (CARD-FISH), Sybr green II direct counting, and the most probable number (MPN) cultivation technique. Depth profiles of cell numbers showed that the compositions of the microbial communities are greatly different at the three sites and also strongly varied between zones of oxidized and unoxidized tailings. Maximum cell numbers of up to 10(9) cells g(-1) dry weight were determined in the pyrite or pyrrhotite oxidation zones, whereas cell numbers in unoxidized tailings were significantly lower. Bacteria dominated over Archaea and Eukarya at all tailing sites. The acidophilic Fe(II)- and/or sulfur-oxidizing Acidithiobacillus spp. dominated over the acidophilic Fe(II)-oxidizing Leptospirillum spp. among the Bacteria at two sites. The two genera were equally abundant at the third site. The acidophilic Fe(II)- and sulfur-oxidizing Sulfobacillus spp. were generally less abundant. The acidophilic Fe(III)-reducing Acidiphilium spp. could be found at only one site. The neutrophilic Fe(III)-reducing Geobacteraceae as well as the dsrA gene of sulfate reducers were quantifiable at all three sites. FISH analysis provided reliable data only for tailing zones with high microbial activity, whereas CARD-FISH, Q-PCR, Sybr green II staining, and MPN were suitable methods for a quantitative microbial community analysis of tailings in general.

Bioleaching of a low-grade nickel-copper sulfide by mixture of four thermophiles.

Science.gov (United States)

Li, Shuzhen; Zhong, Hui; Hu, Yuehua; Zhao, Jiancun; He, Zhiguo; Gu, Guohua

2014-02-01

This study investigated thermophilic bioleaching of a low grade nickel-copper sulfide using mixture of four acidophilic thermophiles. Effects of 0.2g/L l-cysteine on the bioleaching process were further evaluated. It aimed at offering new alternatives for enhancing metal recoveries from nickel-copper sulfide. Results showed a recovery of 80.4% nickel and 68.2% copper in 16-day bioleaching without l-cysteine; while 83.7% nickel and 81.4% copper were recovered in the presence of l-cysteine. Moreover, nickel recovery was always higher than copper recovery. l-Cysteine was found contributing to lower pH value, faster microbial growth, higher Oxidation-Reduction Potential (ORP), higher zeta potential and absorbing on the sulfide surfaces through amino, carboxyl and sulfhydryl groups. X-ray Diffraction (XRD) patterns of leached residues showed generation of S, jarosite and ammoniojarosite. Denaturing Gradient Gel Electrophoresis (DGGE) results revealed that l-cysteine could have variant impacts on different microorganisms and changed the microbial community composition dramatically during nickel-copper sulfide bioleaching. Copyright © 2013 Elsevier Ltd. All rights reserved.

Toward an Integrated Model for the Composition, Structure, and Physical Properties of the Crust in Icelandic Rift Zones

Science.gov (United States)

Kelley, D. F.; Panero, W. R.; Barton, M.

2009-05-01

The rift zones that extend across Iceland roughly southwest to northeast are the only portion of the mid-Atlantic Ridge that is exposed above sea level. This reflects anomalously high melt productivity in the mantle leading to anomalously thick oceanic crust. There are 30 active volcanic centers in the rift zones. Petrologic studies of the 30 volcanic centers in the active rift zones show that, magmas pond at a mid-crustal level as well as at the base of the crust prior to eruption. The depth of magma chambers at the base of the crust provides an estimate of crustal thickness of (20 ± 2.5 km) in these zones. Melts erupting to the surface directly from chambers at the base of the crust provide one constraint on the composition of the crust because any compositional variations within the crust must be the result of differentiation of these melts. However, the glass compositions indicate that relatively evolved magmas erupted from the deep chambers, suggesting that crystallization of compositionally more primitive magmas also occurred at the base of the crust. Knowledge of crustal thickness, the temperature of melts at the base of the crust, and the compositions of these melts allows development of comprehensive models of the composition, structure and properties of crust within the rift zones. We have developed two end member models: one with variation of mineralogy with depth in the crust due to metamorphism, and one with variation of crustal composition with depth due to fractionation processes. We have also considered models that are plausible combinations of these two end member models. We have calculated well constrained geothermal gradients and used these to predict variations in density, seismic velocity, and bulk modulus with depth. These models which include petrologic and geochemical data are consistent with published geophysical data, therefore provide important constraints on interpretation of geophysical data. In particular, results of this work provide

Technetium Reduction and Permanent Sequestration by Abiotic and Biotic Formation of Low-Solubility Sulfide Mineral Phases

Energy Technology Data Exchange (ETDEWEB)

Tratnyek, Paul G. [Oregon Health & Science Univ., Beaverton, OR (United States); Tebo, Bradley M. [Oregon Health & Science Univ., Beaverton, OR (United States); Fan, Dimin [Oregon Health & Science Univ., Beaverton, OR (United States); Anitori, Roberto [Oregon Health & Science Univ., Beaverton, OR (United States); Szecsody, Jim [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jansik, Danielle [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2015-11-14

One way to minimize the mobility of the Tc^VII oxyanion pertechnetate (TcO₄^-) is to effect reduction under sulfidogenic conditions (generated abiotically by Fe₀ or biotically) to form TcS_x, which is significantly slower to oxidize than Tc^IVO₂. In sediment systems, TcS_x and other precipitates may oxidize more slowly due to oxygen diffusion limitations to these low permeability precipitate zones. In addition, the TcO₄^- reduction rate may be more rapid in the presence of sediment because of additional reductive surface phases. This project aims to provide a fundamental understanding of the feasibility of immobilization of TcO₄^- as TcS_x in the vadose zone or groundwater by application nano zero-valent iron (nZVI), and sulfide or sulfate. Biotic batch experiments have used the sulfate-reducing bacterium (SRB) Desulfotomaculum reducens. The iron sulfide mineral mackinawite was generated under these conditions, while vivianite was formed in nZVI only controls. The sulfide/bacteria-containing system consistently reduced aqueous pertechnetate rapidly (> 95% in the first hour), a rate similar to that for the sulfide-free, nZVI only system. Reduced Tc (aged for 3 months) generated in both SRB/nZVI systems was highly resistant to reoxidation. In reduced samples, Tc was found associated with solid phases containing Fe and S (D. reducens/nZVI) or Fe (nZVI only). Experiments using D. reducens without nZVI provided some additional insights. Firstly, stationary phase cultures were able to slowly reduce pertechnetate. Secondly, addition of pertechnetate at the beginning of cell growth (lag phase) resulted in a faster rate of Tc reduction, possibly indicating a direct (e.g. enzymatic) role for D. reducens in Tc reduction. Abiotic batch experiments were conducted with Na₂S as the sulfide source. Pertechnetate reduction was

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.

Optical and structural characteristics of lead sulfides thin films

International Nuclear Information System (INIS)

Karim Deraman; Bakar Ismail; Samsudi Sakrani; Gould, R.D.

1992-01-01

Tin sulfide films have been prepared by evaporation technique at 1x10 - 4 torr and at substrate temperatures between 100 to 300 0 C. The films thickness were 52 to 370 nm. From the absorption 1.47 eV and X-ray diffraction patent shows that the composition of films have changed from SnS 2 (at low temperature) to SnS (at higher temperature)

POROUS MICROSTRUCTURE OF THE INTERFACIAL TRANSITION ZONE IN GEOPOLYMER COMPOSITES

Directory of Open Access Journals (Sweden)

Steinerová M.

2013-12-01

Full Text Available The study deals with a comparison of the differences in the structure, composition and micromechanical properties of a metakaolinite geopolymer composite matrix, inside and outside of the interfacial transition zone (ITZ with quartz grains of added silica sand. The microstructure is investigated by a measurement of the mercury porosimetry, microscopy and by a measurement in SEM and AFM, completed by Raman spectroscopy. Weaker mechanical properties, micropores in the ITZ, a higher concentration of Al atoms and hydroxyl groups than in the ambient matrix were detected. The water transport is probably the reason for the micropore formation, caused by disequilibrium in the course of solid-phase building from geopolymer dispersion.

One-step liquid phase chemical method to prepare carbon-based amorphous molybdenum sulfides: As the effective hydrogen evolution reaction catalysts

International Nuclear Information System (INIS)

Guo, Mengmeng; Wu, Qikang; Yu, Miaomiao; Wang, Yinling; Li, Maoguo

2017-01-01

Two different kinds of carbon-based amorphous molybdenum sulfide composite catalysts (activated carbon supported amorphous molybdenum sulfide and acetylene black supported amorphous molybdenum sulfide) had been prepared in a facile and scalable one-step liquid phase chemical method. The morphological and structural information of catalysts was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and it’s electro-catalytic HER activity were evaluated by linear sweep voltammetry(LSV), amperometric i-t technology and AC impedance technology. The as-prepared carbon-based amorphous molybdenum sulfides showed greatly enhanced electro-catalytic activity for HER compared with pure amorphous molybdenum sulfides. Especially, the nano-sized acetylene black supported molybdenum sulfide exhibited excellent electro-catalytic HER performances with a low onset potential of −116 mV versus reverse hydrogen electrode (RHE) and a small Tafel slope of 51 mV per decade.

Mechanism analysis of improved DLC films friction behaviors with liquid sulfidation treatment

International Nuclear Information System (INIS)

Zeng Qunfeng; Yu Fei; Dong Guangneng; Mao Junhong

2012-01-01

Highlights: ► Liquid sulfidation is applied to treat DLC films. ► Sulfur atoms are chemically bonded and the graphitization presented in the treated films. ► The treated films exhibited much lower coefficient of friction than the untreated films under dry friction condition. ► The sulfidation mechanisms are supposed as surface chemical reaction and surface diffusion. ► The presence of sulfur-containing materials and graphitization are beneficial to improve anti-friction behaviors of the treated films. - Abstract: Diamond like carbon (DLC) films were treated by liquid sulfidation to improve their friction behaviors. Friction behaviors of DLC films were experimentally evaluated in ambient air under dry friction using GCr15 steel ball sliding over DLC-coated steel flat in a ball-on-disk tribometer system. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were applied to identify the chemical composition and structure of DLC films. It was found that the content of sp 2 carbon bond increased and G peak shifted to high wave number after sulfidation treatment. The measurement results showed that sulfur atoms were chemically bonded and the graphitization occurred in the treated DLC films. It was indicated that the treated DLC films exhibited much better friction behaviors than the untreated films, especially for DLC films deposited with high nitrogen ratio. In this paper, we proposed the possible sulfidation mechanism of sulfurized DLC films. Sulfidation mechanism is postulated that thiourea reacted with oxygen to form sulfur-containing organic compounds which included CSSC, CSOH and (NH 2 )NH=CSO 2 H and surface diffusion during sulfidation treatment. The anti-friction behaviors of the treated DLC films can be attributed to the production of the compounds containing sulfur on the DLC film surface, the reduce of oxygen content and the presence of graphitization of DLC films.

A Cryptic Sulfur Cycle in Oxygen-Minimum-Zone Waters off the Chilean Coast

OpenAIRE

Canfield, D. E.; Thamdrup, B.; De Brabandere, L.; Dalsgaard, T.; Revsbech, N. P.; Ulloa, O.; Stewart, Frank J.; DeLong, Edward Francis

2010-01-01

Nitrogen cycling is normally thought to dominate the biogeochemistry and microbial ecology of oxygen-minimum zones in marine environments. Through a combination of molecular techniques and process rate measurements, we showed that both sulfate reduction and sulfide oxidation contribute to energy flux and elemental cycling in oxygen-free waters off the coast of northern Chile. These processes may have been overlooked because in nature, the sulfide produced by sulfate reduction immediately oxid...

Thickness, Composition and Physical Properties of Crust in Iceland's Neovolcanic Zone

Science.gov (United States)

Kelley, D. F.; Barton, M.

2005-12-01

We report the results of an ongoing effort to use petrologic data to estimate the thickness, composition and physical properties of crust in the neovolcanic zone of Iceland. The objectives are to constrain the depths of magma chambers, calculate geothermal gradients, and resolve discrepancies in the interpretation of geophysical data (primarily gravity and seismic). 1788 whole rock analyses and 170 glass analyses of erupted Icelandic lavas from the neovolcanic zone have been compiled from published papers. Variation diagrams indicate that Icelandic magmas evolved primarily by crystallization of Ol-Cpx-Plag, whereas the most primitive magmas evolved by crystallization of Ol alone. Phase equilibrium constraints were used to quantitatively estimate the pressure of crystallization along the Ol-Cpx-Plag cotectic and hence the depths of the magma chambers. The latter occur at 20±6.2 km, and the average temperature of magma in the chambers is 1207±26°C (also estimated from phase equilibrium constraints). The results suggest magma chambers located at the base of the crust indicating that the latter is ~20 km thick along the neovolcanic zone in agreement with estimates based on geophysical studies. It is argued that the average composition of erupted lavas provides an accurate estimate of crustal composition because magma evolution occurs in sub-crustal chambers. A representative geothermal gradient was calculated using the average crust composition and surface heat flow measurements. The calculated gradient is consistent with the periodic presence of shallow intracrustal magma chambers at ~5 km depth that have been detected seismically, with hydrothermal circulation in the uppermost 3 km of the crust, and with temperatures of ~1200°C at the base of the crust. The geotherm was used to calculate a density-depth profile for average crust. Densities decrease with depth if a low-pressure mineralogy is used for the crust. This density inversion can be avoided by assuming

Response of gut health and microbiota to sulfide exposure in Pacific white shrimp Litopenaeus vannamei.

Science.gov (United States)

Suo, Yantong; Li, Erchao; Li, Tongyu; Jia, Yongyi; Qin, Jian G; Gu, Zhimin; Chen, Liqiao

2017-04-01

Sulfide is a natural and widely distributed toxicant. It can be commonly found on the interface between water and sediment in the aquatic environment. The Pacific white shrimp Litopenaeus vannamei starts life in the benthic zone soon after the mysis stage, an early stage of post larvae. Therefore, L. vannamei is inevitably affected by exposure to sulfide released from pond sediment. This study explored the toxicant effect of different concentrations of sulfide on the intestinal health and microbiota of Pacific white shrimp by monitoring the change of expression of inflammatory, immune related cytokines, and the structure of the intestinal microbiota. The gut histology, expressions of inflammatory and immune related cytokines (tumor necrosis factor-alpha, C-type lectin 3, myostatin and heat shock transcription factor 1), and the microbiota were determined in L. vannamei after exposure to 0 (control), 425.5 (1/10 LC 50-96 h), and 851 μg/L (1/5 LC 50-96 h) of sulfide for 21 days. With the increase of sulfide concentration, intestinal injury was aggravated and the inflammatory and immune related cytokines generated a range of reactions. The expression of myostatin (MSTN) was significantly down-regulated by the concentration of sulfide exposure. No difference in the expression of heat shock transcription factor 1 (HSF1) was found between the control and shrimp exposed to 425.5 μg/L, but significantly higher HSF1 expression was found in shrimp exposed to 851 μg/L of sulfide. Significantly higher values of tumor necrosis factor-alpha (TNF-α) and C-type lectin 3 (CTL3) were found in the shrimp exposed to 425.5 μg/L of sulfide compared to the control, but a lower value was found in the shrimp exposed to 851 μg/L (P < 0.05). Sulfide also changed the intestinal microbial communities. The abundance of pathogenic bacteria, such as Cyanobacteria, Vibrio and Photobacterium, increased significantly with exposure to the increasing concentration of sulfide. The

Effects of humic substances 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.

Hydrogen evolution at nanoporous gold/tungsten sulfide composite film and its optimization

DEFF Research Database (Denmark)

Xiao, Xinxin; Engelbrekt, Christian; Li, Zheshen

2015-01-01

Development of efficient and economical electrochemical systems for water splitting is a key part of renewable energy technology. Amorphous films of tungsten sulfide have been deposited by electrochemical reduction of tetrathiotungstate ions (WS42-) on dealloyed nanoporous gold (NPG) for electroc......-term stability. The measured Tafel slope of 74 mV dec-1 implies an underlying Volmer-Heyrovsky HER mechanism....

Geochemical features of sulfides from the Deyin-1 hydrothermal field at the southern Mid-Atlantic Ridge near 15°S

Science.gov (United States)

Wang, Shujie; Li, Huaiming; Zhai, Shikui; Yu, Zenghui; Cai, Zongwei

2017-12-01

In this study, geochemical compositions of elements in sulfide samples collected from the Deyin-1 hydrothermal field near the 15°S southern Mid-Atlantic Ridge (SMAR) were analyzed by the X-ray fluorescence spectrometry (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) to examine the enrichment regulations of ore-forming elements and hydrothermal mineralization. These sulfide precipitates can be classified macroscopically into three types: Fe-rich sulfide, Fe-Cu-rich sulfide and Fe-Zn-rich sulfide, and are characterized by the enrichment of base metal elements along with a sequence of Fe>Zn>Cu. Compared with sulfides from other hydrothermal fields on MAR, Zn concentrations of sulfides in the research area are significantly high, while Cu concentrations are relatively low. For all major, trace or rare-earth elements (REE), their concentrations and related characteristic parameters exhibit significant variations (up to one or two orders of magnitude), which indicates the sulfides from different hydrothermal vents or even a same station were formed at different stages of hydrothermal mineralization, and suggests the variations of chemical compositions of the hydrothermal fluid with respect to time. The hydrothermal temperatures of sulfides precipitation decreased gradually from station TVG10 (st.TVG10) to st.TVG12, and to st.TVG11, indicating that the precipitation of hydrothermal sulfides is subjected to conditions changed from high temperature to low temperature, and that the hydrothermal activity of study area was at the late stage of a general trend of evolution from strong to weak. The abnormally low concentrations of REE in sulfides and their similar chondrite-normalized REE patterns show that REEs in all sulfides were derived from a same source, but underwent different processes of migration or enrichment, or sulfides were formed at different stages of hydrothermal mineralization. The sulfides collected from the active hydrothermal vent were

Acid production potentials of massive sulfide minerals and lead-zinc mine tailings: a medium-term study.

Science.gov (United States)

Çelebi, Emin Ender; Öncel, Mehmet Salim; Kobya, Mehmet

2018-01-01

Weathering of sulfide minerals is a principal source of acid generation. To determine acid-forming potentials of sulfide-bearing materials, two basic approaches named static and kinetic tests are available. Static tests are short-term, and easily undertaken within a few days and in a laboratory. In contrast, kinetic tests are long-term procedures and mostly carried out on site. In this study, experiments were conducted over a medium-term period of 2 months, not as short as static tests and also not as long as kinetic tests. As a result, pH and electrical conductivity oscillations as a function of time, acid-forming potentials and elemental contents of synthetically prepared rainwater leachates of massive sulfides and sulfide-bearing lead-zinc tailings from abandoned and currently used deposition areas have been determined. Although the lowest final pH of 2.70 was obtained in massive pyrite leachate, massive chalcopyrite leachate showed the highest titrable acidity of 1.764 g H 2 SO 4 /L. On the other hand, a composite of currently deposited mine tailings showed no acidic characteristic with a final pH of 7.77. The composite abandoned mine tailing leachate had a final pH of 6.70, close to the final pH of massive galena and sphalerite leachates, and produced a slight titrable acidity of 0.130 g H 2 SO 4 /L.

The effect of sulfide on the aerobic corrosion of carbon steel in near-neutral pH saline solutions

International Nuclear Information System (INIS)

Sherar, B.W.A.; Keech, P.G.; Shoesmith, D.W.

2013-01-01

Highlights: ► The corrosion rate is low when steel is exposed to anaerobic conditions (pH = 8.9). ► An anaerobic to aerobic corrosion with sulfide switch increases the corrosion rate. ► Aerobic exposure induces the formation of goethite-covered tubercles. ► Continual sulfide exposure leads to the slow conversion of goethite to mackinawite. - Abstract: Severe corrosion damage may occur when gas transmission pipelines are exposed, at disbonded coating locations, to trapped waters containing sulfide followed by secondary exposure to air. Aerobic corrosion with sulfide was investigated in a long-term corrosion experiment in which corrosion was monitored by measurement of the corrosion potential and polarization resistance obtained from linear polarization resistance measurements. The properties and composition of the corrosion product deposits formed were determined using scanning electron microscopy, energy dispersive X-ray analysis, and Raman spectroscopy. A switch from aerobic to aerobic-with-sulfide corrosion doubles the relative corrosion rate.

Air-water transfer of hydrogen sulfide

DEFF Research Database (Denmark)

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

2004-01-01

The emissions process of hydrogen sulfide was studied to quantify air–water transfer of hydrogen sulfide in sewer networks. Hydrogen sulfide transfer across the air–water interface was investigated at different turbulence levels (expressed in terms of the Froude number) and pH using batch...... 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...

A highly stable and sensitive chemically modified screen-printed electrode for sulfide analysis

Energy Technology Data Exchange (ETDEWEB)

Tsai, D.-M. [Department of Chemistry, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 40217, Taiwan (China); Kumar, Annamalai Senthil [Department of Chemistry, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 40217, Taiwan (China); Zen, J.-M. [Department of Chemistry, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 40217, Taiwan (China)]. E-mail: jmzen@dragon.nchu.edu.tw

2006-01-18

We report here a highly stable and sensitive chemically modified screen-printed carbon electrode (CMSPE) for sulfide analysis. The CMSPE was prepared by first ion-exchanging ferricyanide into a Tosflex anion-exchange polymer and then sealing with a tetraethyl orthosilicate sol-gel layer. The sol-gel overlayer coating was crucial to stabilize the electron mediator (i.e., Fe(China){sub 6} {sup 3-}) from leaching. The strong interaction between the oxy-hydroxy functional group of sol-gel and the hydrophilic sites of Tosflex makes the composite highly rigid to trap the ferricyanide mediator. An obvious electrocatalytic sulfide oxidation current signal at {approx}0.20 V versus Ag/AgCl in pH 7 phosphate buffer solution was observed at the CMSPE. A linear calibration plot over a wide range of 0.1 {mu}M to 1 mM with a slope of 5.6 nA/{mu}M was obtained by flow injection analysis. The detection limit (S/N = 3) was 8.9 nM (i.e., 25.6 ppt). Practical utility of the system was applied to the determination of sulfide trapped from cigarette smoke and sulfide content in hot spring water.

Solar cells with PbS quantum dot sensitized TiO2-multiwalled carbon nanotube composites, sulfide-titania gel and tin sulfide coated C-fabric.

Science.gov (United States)

Kokal, Ramesh K; Deepa, Melepurath; Kalluri, Ankarao; Singh, Shrishti; Macwan, Isaac; Patra, Prabir K; Gilarde, Jeff

2017-10-04

Novel approaches to boost quantum dot solar cell (QDSC) efficiencies are in demand. Herein, three strategies are used: (i) a hydrothermally synthesized TiO 2 -multiwalled carbon nanotube (MWCNT) composite instead of conventional TiO 2 , (ii) a counter electrode (CE) that has not been applied to QDSCs until now, namely, tin sulfide (SnS) nanoparticles (NPs) coated over a conductive carbon (C)-fabric, and (iii) a quasi-solid-state gel electrolyte composed of S 2- , an inert polymer and TiO 2 nanoparticles as opposed to a polysulfide solution based hole transport layer. MWCNTs by virtue of their high electrical conductivity and suitably positioned Fermi level (below the conduction bands of TiO 2 and PbS) allow fast photogenerated electron injection into the external circuit, and this is confirmed by a higher efficiency of 6.3% achieved for a TiO 2 -MWCNT/PbS/ZnS based (champion) cell, compared to the corresponding TiO 2 /PbS/ZnS based cell (4.45%). Nanoscale current map analysis of TiO 2 and TiO 2 -MWCNTs reveals the presence of narrowly spaced highly conducting domains in the latter, which equips it with an average current carrying capability greater by a few orders of magnitude. Electron transport and recombination resistances are lower and higher respectively for the TiO 2 -MWCNT/PbS/ZnS cell relative to the TiO 2 /PbS/ZnS cell, thus leading to a high performance cell. The efficacy of SnS/C-fabric as a CE is confirmed from the higher efficiency achieved in cells with this CE compared to the C-fabric based cells. Lower charge transfer and diffusional resistances, slower photovoltage decay, high electrical conductance and lower redox potential impart high catalytic activity to the SnS/C-fabric assembly for sulfide reduction and thus endow the TiO 2 -MWCNT/PbS/ZnS cell with a high open circuit voltage (0.9 V) and a large short circuit current density (∼20 mA cm -2 ). This study attempts to unravel how simple strategies can amplify QDSC performances.

The role of diallyl sulfides and dipropyl sulfides in the in vitro antimicrobial activity of the essential oil of garlic, Allium sativum L., and leek, Allium porrum L.

Science.gov (United States)

Casella, Sergio; Leonardi, Michele; Melai, Bernardo; Fratini, Filippo; Pistelli, Luisa

2013-03-01

The in vitro antibacterial activity of essential oils (EOs) obtained from fresh bulbs of garlic, Allium sativum L., and leek, Allium porrum L. ( Alliaceae), was studied. A. sativum (garlic) EO showed a good antimicrobial activity against Staphylococcus aureus (inhibition zone 14.8 mm), Pseudomonas aeruginosa (inhibition zone 21.1 mm), and Escherichia coli (inhibition zone 11.0 mm), whereas the EO of A. porrum (leek) had no antimicrobial activity. The main constituents of the garlic EO were diallyl monosulfide, diallyl disulfide (DADS), diallyl trisulfide, and diallyl tetrasulfide. The EO of A. porrum was characterized by the presence of dipropyl disulfide (DPDS), dipropyl trisulfide, and dipropyl tetrasulfide. The antimicrobial activities of the DADS and DPDS were also studied. The results obtained suggest that the presence of the allyl group is fundamental for the antimicrobial activity of these sulfide derivatives when they are present in Allium or in other species (DADS inhibition zone on S. aureus 15.9 mm, P. aeruginosa 21.9 mm, E. coli 11.4 mm). Copyright © 2012 John Wiley & Sons, Ltd.

Carbon steel protection in G.S. (Girlder sulfide) plants. Influence of the material surface state. Pt. 2

International Nuclear Information System (INIS)

Burkart, A.L.; Garavaglia, R.N.

1983-05-01

The passivation on carbon steels, in particular ASTM A 516 Degree 60 and ASTM A 333 steels is made, submitting it to the action of H 2 S/H 2 O 1,2 corrosive medium. The steel is rapidly corroded by H 2 S in aqueous solution, forming iron sulfides on the metallic surface in a crystalline layer of various μm of thickness. During this process, various types of iron sulfides at different phases, with different sulfur and iron contents are formed. The influence of temperature, the pH, the exposure time and the corrosive medium composition on formation and quality of the iron sulfides protective layer was also studied. (Author) [es

Electrochemical deposition of iron sulfide thin films and heterojunction diodes with zinc oxide

Directory of Open Access Journals (Sweden)

Shoichi Kawai

2014-03-01

Full Text Available Iron sulfide thin films were fabricated by the electrochemical deposition method from an aqueous solution containing FeSO4 and Na2S2O3. The composition ratio obtained was Fe:S:O = 36:56:8. In the photoelectrochemical measurement, a weak negative photo-current was observed for the iron sulfide films, which indicates that its conduction type is p-type. No peaks were observed in X-ray diffraction pattern, and thus the deposited films were considered to be amorphous. For a heterojunction with ZnO, rectification properties were confirmed in the current-voltage characteristics. Moreover, the current was clearly enhanced under AM1.5 illumination.

Stable Nd isotope variations in the inner Solar System: The effect of sulfide during differentiation?

Science.gov (United States)

McCoy-West, A.

2017-12-01

Radiogenic neodymium isotopes have been widely used in studies of planetary accretion to constrain the timescales of early planetary differention [1]. Whereas stable isotope varitaions potentially provide information on the the processes that occur during planet formation. Experimental work suggests that the Earth's core contains a significant proportion of sulfide [2], and recent experimental work shows that under reducing conditions sulfide can incorporate substantial quantities of refractory lithophile elements [including Nd; 3]. If planetary embroyos also contain sulfide-rich cores, Nd stable isotopes have the potential to trace this sulfide segregation event in highly reduced environments, because there is a significant contrast in bonding environment between sulfide and silicate, where heavy isotopes should be preferentially incorporated into high force-constant bonds involving REE3+ (i.e. the silicate mantle). Here we present 146Nd/144Nd data, obtained using a double spike TIMS technique, for a range of planetary bodies formed at variable oxidation states including samples from the Moon, Mars, the asteriod 4Vesta and the Angrite and Aubrite parent bodies. Analyses of chondritic meteorites and terrestrial igneous rocks indicate that the Earth has a Nd stable isotope composition that is indistinguishable from that of chondrites [4]. Eucrites and martian meteorites also have compositons within error of the chondritic average. Significantly more variabilty is observed in the low concentration lunar samples and diogienite meteorites with Δ146Nd = 0.16‰. Preliminary results suggest that the Nd stable isotope composition of oxidised planetary bodies are homogeneous and modifications are the result of subordinate magmatic processes. [1] Boyet & Carlson, Science 309, 576 (2005) [2] Labidi et al. Nature 501, 208 (2013); [3] Wohlers &Wood, Nature 520, 337 (2015); [4] McCoy-West et al. Goldschmidt Ab. 429 (2017).

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...

A batch assay to measure microbial hydrogen sulfide production from sulfur-containing solid wastes

International Nuclear Information System (INIS)

Sun, Mei; Sun, Wenjie; Barlaz, Morton A.

2016-01-01

Large volumes of sulfur-containing wastes enter municipal solid waste landfills each year. Under the anaerobic conditions that prevail in landfills, oxidized forms of sulfur, primarily sulfate, are converted to sulfide. Hydrogen sulfide (H 2 S) is corrosive to landfill gas collection and treatment systems, and its presence in landfill gas often necessitates the installation of expensive removal systems. For landfill operators to understand the cost of managing sulfur-containing wastes, an estimate of the H 2 S production potential is needed. The objective of this study was to develop and demonstrate a biochemical sulfide potential (BSP) test to measure the amount of H 2 S produced by different types of sulfur-containing wastes in a relatively fast (30 days) and inexpensive (125 mL serum bottles) batch assay. This study confirmed the toxic effect of H 2 S on both sulfate reduction and methane production in batch systems, and demonstrated that removing accumulated H 2 S by base adsorption was effective for mitigating inhibition. H 2 S production potentials of coal combustion fly ash, flue gas desulfurization residual, municipal solid waste combustion ash, and construction and demolition waste were determined in BSP assays. After 30 days of incubation, most of the sulfate in the wastes was converted to gaseous or aqueous phase sulfide, with BSPs ranging from 0.8 to 58.8 mL H 2 S/g waste, depending on the chemical composition of the samples. Selected samples contained solid phase sulfide which contributed to the measured H 2 S yield. A 60 day incubation in selected samples resulted in 39–86% additional sulfide production. H 2 S production measured in BSP assays was compared with that measured in simulated landfill reactors and that calculated from chemical analyses. H 2 S production in BSP assays and in reactors was lower than the stoichiometric values calculated from chemical composition for all wastes tested, demonstrating the importance of assays to estimate the

Zinc sulfide in intestinal cell granules of Ancylostoma caninum adults

Energy Technology Data Exchange (ETDEWEB)

Gianotti, A.J.; Clark, D.T.; Dash, J. (Portland State Univ., OR (USA))

1991-04-01

A source of confusion has existed since the turn of the century about the reddish brown, weakly birefringent 'sphaerocrystals' located in the intestines of strongyle nematodes, Strongylus and Ancylostoma. X-ray diffraction and energy dispersive spectrometric analyses were used for accurate determination of the crystalline order and elemental composition of the granules in the canine hookworm Ancylostoma caninum. The composition of the intestinal pigmented granules was identified unequivocally as zinc sulfide. It seems most probable that the granules serve to detoxify high levels of metallic ions (specifically zinc) present due to the large intake of host blood.

Texture, microstructure and geochemistry of magnetite from the Banduhurang uranium mine, Singhbhum shear zone, India - implications for physico-chemical evolution of magnetite mineralization

International Nuclear Information System (INIS)

Ghosh, Dibakar; Dutta, Tusar; Samanta, Susanta K.; Pal, Dipak C.

2013-01-01

The Singhbhum Shear zone in eastern India is one of the largest repositories of uranium and copper in India. Besides uranium and copper, apatite-magnetite mineralization is widespread in this shear zone. This study aims at deciphering the physico-chemical evolution of magnetite mineralization in relation to progressive shearing integrating field relations, micro-textures, structures and compositions of magnetite in the Banduhurang uranium mine. Apatite-magnetite ores occur as discrete patches, tongues, and veins in the strongly deformed, fine grained quartz-chlorite schist. Textures and microstructures of magnetite indicate at least three stages of magnetite formation. Coarse-grained magnetite (magnetite-1) with long, rotational, and complex strain fringes, defined by fibrous and elongate quartz, is assigned to a stage of pre-/early-shearing magnetite formation. Medium grained magnetite (magnetite-2), characterized by single non-rotational strain fringe equivalent to the youngest fringe of magnetite-1, grew likely at the mid-/late-stage of shearing. Fine grained magnetite (magnetite-3) is generally devoid of any pressure shadow. This indicates even a much later stage of formation of this magnetite, presumably towards the closing stage of shearing. Some of the magnetite-1 grains are optically heterogeneous with a dark, pitted Cr-Ti-bearing core overgrown by lighter, fresh rim locally containing pyrite, chalcopyrite, and chlorite inclusions. The cores are also locally characterized by high AI and Si content. Homogeneous magnetite-1 is optically and compositionally similar to the overgrowth of heterogeneous magnetite-1. This homogeneous magnetite-1 that grew as separate phase is contemporaneous with the overgrowth on pitted core of heterogeneous magnetite-1. Magnetite-2 is compositionally very similar to homogeneous magnetite-1, but is devoid of sulfide inclusion. Magnetite-3 is generally devoid of any silicate or sulfide inclusion and is most pure with least

Carbon steel protection in G.S. (Girlder sulfide) plants. Iron sulfide scales formation conditions. Pt. 1

International Nuclear Information System (INIS)

Bruzzoni, P.; Burkart, A.L.; Garavaglia, R.N.

1981-11-01

An ASTM A 516 degree 60 carbon steel superficial protection technique submitted to a hydrogen-water sulfide corrosive medium at 2 MPa of pressure and 40-125 deg C forming on itself an iron sulfide layer was tested. Studies on pH influence, temperature, passivating mean characteristics and exposure time as well as the mechanical resistance of sulfide layers to erosion are included. (Author) [es

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....

Age measurements of potassium-bearing sulfide minerals by the 40Ar/39Ar technique

International Nuclear Information System (INIS)

Czamanske, G.K.; Lanphere, M.A.; Erd, R.C.; Blake, M.C. Jr.

1978-01-01

K-Ar ages have been determined for sulfide minerals for the first time. The occurrence of adequate amounts of potassium-bearing sulfides with ideal compositions K 3 Fe 10 S 14 (approximately 10 wt.% K) and KFe 2 S 3 (approximately 16 wt.% K) in samples from a mafic alkalic diatreme at Coyote Peak, California, prompted an attempt to date these materials. K 3 Fe 10 S 14 , a massive mineral with conchoidal fracture, gives an age of 29.4 +- 0.5 m.y. ( 40 Ar/ 39 Ar), indistinguishable from the 28.3 +- 0.4 m.y. ( 40 Ar/ 39 Ar) and 30.2 +- 1.0 m.y. (conventional K-Ar) ages obtained for associated phlogopite (8.7 wt.% K). KFe 2 S 3 , a bladed, fibrous sulfide, gives a younger age, 26.5 +- 0.5 m.y. ( 40 Ar/ 39 Ar), presumably owing to Ar loss. (Auth.)

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...

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...... as sulfate throughout the plant. We conclude that avoidance of sulfide exposure by reoxidation of sulfide in the rhizosphere or aerenchyma and tolerance of sulfide intrusion by incorporation of sulfur in the plant are likely major survival strategies of seagrasses in sulfidic sediments....

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

Optimum injection dose rate of hydrogen sulfide scavenger for treatment of petroleum crude oil

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T.M. Elshiekh

2016-03-01

Full Text Available Hydrogen sulfide H2S scavengers are chemicals that favorably react with hydrogen sulfide gas to eliminate it and produce environmental friendly products. These products depend on the type and composition of the scavenger and the conditions at which the reaction takes place. The scavenger should be widely available and economical for industry acceptance by having a low unit cost. The optimum values of H2S scavenger injection dose rate of scavenging hydrogen sulfide from the multiphase fluid produced at different wells conditions in one of the Petroleum Companies in Egypt were studied. The optimum values of H2S scavenger injection dose rate depend on pipe diameter, pipe length, gas molar mass velocity, inlet H2S concentration and pressure. The optimization results are obtained for different values of these parameters using the software program Lingo. In general, the optimum values of H2S scavenger injection dose rate of the scavenging of hydrogen sulfide are increased by increasing of the pipe diameter and increasing the inlet H2S concentration, and decreased by increasing the pipe length, gas molar mass velocity and pressure.

Long-term corrosion of copper in a dilute anaerobic sulfide solution

Energy Technology Data Exchange (ETDEWEB)

Chen, J.; Qin, Z. [Department of Chemistry, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Shoesmith, D.W., E-mail: dwshoesm@uwo.ca [Department of Chemistry, University of Western Ontario, London, Ontario, N6A 5B7 (Canada)

2011-09-30

The mechanism of corrosion of oxygen-free copper has been studied in stagnant aqueous sulfide solutions using corrosion potential and electrochemical impedance spectroscopy (EIS) measurements. Film structure and composition were examined on surfaces and on cross-sections prepared by focused ion beam (FIB) milling using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Experiments were conducted in anaerobic 5 x 10{sup -5} mol dm{sup -3} Na{sub 2}S + 0.1 mol dm{sup -3} NaCl solutions for exposure periods up to 4000 h ({approx}167 days) to mimic (at least partially) the conditions that could develop on a copper nuclear fuel waste container in a deep geologic repository. The corrosion film formed was a single cellular Cu{sub 2}S layer with a non-uniform thickness. The film thickness increased approximately linearly with immersion time, which implied that the sulfide film formed on the Cu surface is non-protective under these conditions up to this exposure time. The film growth process was controlled by HS{sup -} diffusion partially in the aqueous solution in the pores in the cellular sulfide film and partially in the bulk of the aqueous solution.

Identification of mineralized zones in the Zardu area, Kushk SEDEX deposit (Central Iran, based on geological and multifractal modeling

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Dahooei Ahmad Heidari

2016-02-01

Full Text Available The aim of this paper is to delineate the different lead–zinc mineralized zones in the Zardu area of the Kushk zinc–lead stratabound SEDEX deposit, Central Iran, through concentration–volume (C–V modeling of geological and lithogeochemical drillcore data. The geological model demonstrated that the massive sulfide and pyrite+dolomite ore types as main rock types hosting mineralization. The C–V fractal modeling used lead, zinc and iron geochemical data to outline four types of mineralized zones, which were then compared to the mineralized rock types identified in the geological model. ‘Enriched’ mineralized zones contain lead and zinc values higher than 6.93% and 19.95%, respectively, with iron values lower than 12.02%. Areas where lead and zinc values were higher than 1.58% and 5.88%, respectively, and iron grades lower than 22% are labelled “high-grade” mineralized zones, and these zones are linked to massive sulfide and pyrite+dolomite lithologies of the geological model. Weakly mineralized zones, labelled ‘low-grade’ in the C– V model have 0–0.63% lead, 0–3.16% zinc and > 30.19% iron, and are correlated to those lithological units labeled as gangue in the geological model, including shales and dolomites, pyritized dolomites. Finally, a log-ratio matrix was employed to validate the results obtained and check correlations between the geological and fractal modeling. Using this method, a high overall accuracy (OA was confirmed for the correlation between the enriched and high-grade mineralized zones and two lithological units — the massive sulfide and pyrite+dolomite ore types.

Synthesis of bismuth sulfide/reduced graphene oxide composites and their electrochemical properties for lithium ion batteries

International Nuclear Information System (INIS)

Zhang, Zhian; Zhou, Chengkun; Huang, Lei; Wang, Xiwen; Qu, Yaohui; Lai, Yanqing; Li, Jie

2013-01-01

Graphical abstract: The Bi 2 S 3 /reduced graphene oxide composites were synthesized by a one-pot hydrothermal route and exhibited an extraordinary capacity of 1073.1 mAh g −1 with excellent cycling stability and high rate capability as anode material of lithium ion battery. The enhancement in the electrochemical performance could be attributed to the introduction of RGO sheets that not only buffer the large volume changes during the alloy/dealloy reaction of Li and Bi, but also provide a highly conductive network for rapid electron transport in electrode during electrochemical reaction. -- Highlights: •Bi 2 S 3 /RGO composites were in situ prepared by one-pot hydrothermal route. •The Bi 2 S 3 nanoparticles are homogeneous dispersion on the RGO sheets. •Bi 2 S 3 /RGO exhibits excellent cycling stability and high rate capability. •This work will also of interest for supercapacitor and solar cells. -- Abstract: A simple one-pot hydrothermal route was developed to synthesize bismuth sulfide/reduced graphene oxide composites (Bi 2 S 3 /RGO composites) in this work. The morphology and crystalline structure of the obtained products were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high resolution transmission electron microscopy (HRTEM). The results of Raman spectra and Fourier transform infrared (FTIR) spectra demonstrated that graphite oxide (GO) sheets were in situ reduced to a certain extent. Transmission electron microscopy (TEM) observation indicated that the Bi 2 S 3 nanoparticles, with a size of 80–100 nm in length, are anchored on RGO sheets. Electrochemical tests show the Bi 2 S 3 /RGO composite exhibits an extraordinary capacity of 1073.1 mAh g −1 with excellent cycling stability and high rate capability compared to pure Bi 2 S 3 particles prepared by a similar route in the absence of GO. The enhancement in the electrochemical performance could be attributed to the introduction of RGO sheets

Compositional Approach to Designing Fcc High-Entropy Alloys that Have an Enlarged Equiaxed Zone

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Minju Kang

2018-01-01

Full Text Available A compositional approach to designing alloys that have an enlarged equiaxed zone is suggested in this study. The partitioning of elements during the solidification of CoCrFeMnNi high-entropy alloy (HEA was confirmed through a directional solidification quenching experiment. Several HEAs were designed to maximize the effects of constitutional and thermal undercooling by considering factors including solute enrichment at the columnar front and the melting temperatures and thermal conductivities of the individual elements. The newly designed HEAs were shown to have successfully enlarged equiaxed zones, and improved anisotropic properties.

Electron transfer to sulfides:

International Nuclear Information System (INIS)

Meneses, Ana Belen; Antonello, Sabrina; Arevalo, Maria Carmen; Maran, Flavio

2005-01-01

The problem of characterizing the steps associated with the dissociative reduction of sulfides has been addressed. The electrochemical reduction of diphenylmethyl para-methoxyphenyl sulfide in N,N-dimethylformamide, on both glassy carbon and mercury electrodes, was chosen as a test system. The electrode process involves the slow heterogeneous outer-sphere electron transfer to the sulfide, the fast cleavage of the C-S bond, the reduction of the ensuing carbon radical, and the self-protonation triggered by the generation of the strong base Ph 2 CH - . The latter reaction is rather slow, in agreement with the large intrinsic barriers characterizing proton transfers between CH-acids and carbon bases. The dissociative reduction was studied in the presence of an exogenous acid. The results, obtained by convolution analysis, point to a stepwise DET mechanism in which the ET step is accompanied by rather large reorganization energy. Similar results were obtained on both electrode materials. Analysis of the heterogeneous electron transfer and associated C-S bond cleavage indicate that the reduction of this and other sulfides lies between the stepwise dissociative electron transfers leading to the formation of stiff π* radical anions and those going through the intermediacy of loose σ* radical anions

Investigation of physicochemical and pigment properties of solid solutions of cadmium, manganese, zinc sulfides

International Nuclear Information System (INIS)

Grigor'eva, L.I.; Ignat'eva, I.V.; Kalinskaya, T.V.

1985-01-01

Mixed sulfides (Cd, Mn)S and (Cd, Mn, Zn)S with manganese sulfide content upto 50 mol% are synthesized. The possibility of preparing solid solutions both on the basis of silfides (Cd, Mn)S and in the ternary system (Cd, Mn, Zn)S with the temperature of polymorphic transformation of a cubic structure into a hexagonal one, being lower (500 deg C) than in the absence of MnS, is shown by the X-ray diffraction method. The colour analysis of the pigment specimens obtained has shown that the quantity of oxidized manganese compounds, producing no effect of the system colour, should not exceed 0.05 mol% on conversion to MnS. Among the mixed specimens (Cd, Mn)S the brightest colour background is obtained for specimens calcinated at 500-550 deg C. The mixed sulfide of the composition 0.77CdSx0.15MnSx0.08ZnS, calcinated at 500 deg C, gives a pigment corresponding to a commercial one by colour

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

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

Sulfide geochronlogy along the Southwest Indian Ridge

Science.gov (United States)

Yang, W.; Tao, C.; Li, H.; Liang, J.; Liao, S.

2017-12-01

Dragon Flag and Duanqiao hydrothermal field is located between the Indomed and Gallieni fracture zones in the ultraslow-spreading Southwest Indian Ridge (SWIR). Ten subsamples from active and inactive vents of Dragon Flag hydrothermal field and twenty-eight subsamples from Duanqiao hydrothermal field were dated using the 230Th/238U method. Four main episodes of hydrothermal activity of Duanqiao were determined according to the restricted results: 68.9-84.3, 43.9-48.4, 25.3-34.8, and 0.7-17.3 kyrs. Hydrothermal activity of Duanqiao probably started about 84.3 (±0.5) kyrs ago and ceased about 0.737 (±0.023) kyrs ago. And sulfide samples from the nearby Dragon Flag filed at the same time and the results show that the ages of most sulfides from Dragon Flag field range from 1.496(±0.176) to 5.416 (±0.116) kyrs with the oldest age estimated at 15.997 (±0.155) kyrs Münch et al. (2001) reconstructed the evolution history of Mt. Jourdanne hydrothermal field. The age dating results indicate activity in two episodes, at 70-40 and 27-13 kyrs. The hydrothermal activity in Dragon Flag field is much more recent than that of Duanqiao or Mt. Jourdanne fields. The massive sulfides are younger than the sulfides from other hydrothermal fields such as Rainbow, Sonne and Ashadze-2. All these results suggest that hydrothermal activity of Dragon Flag field is much more recent than that of Duanqiao or Mt. Jourdanne fields. Mt. Jourdanne is situated on an axial volcanic ridge which has both volcanic and tectonic activity. This is necessary to develop the heat source and pathways for the fluid convection, which enables the hydrothermal circulation. Hydrothermal activity in Dragon Flag Field is located next to the detachment fault termination. The detachment fault system provides a pathway for hydrothermal convection. Such style of heat source can contribute to continuous hydrothermal activity for over 1000 years. Duanqiao field is located near the central volcano and there is a hot

A batch assay to measure microbial hydrogen sulfide production from sulfur-containing solid wastes

Energy Technology Data Exchange (ETDEWEB)

Sun, Mei, E-mail: msun8@uncc.edu [Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Campus Box 7908, Raleigh, NC (United States); Sun, Wenjie, E-mail: wsun@smu.edu [Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Campus Box 7908, Raleigh, NC (United States); Department of Civil and Environmental Engineering, Southern Methodist University, PO Box 750340, Dallas, TX (United States); Barlaz, Morton A., E-mail: barlaz@ncsu.edu [Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Campus Box 7908, Raleigh, NC (United States)

2016-05-01

Large volumes of sulfur-containing wastes enter municipal solid waste landfills each year. Under the anaerobic conditions that prevail in landfills, oxidized forms of sulfur, primarily sulfate, are converted to sulfide. Hydrogen sulfide (H{sub 2}S) is corrosive to landfill gas collection and treatment systems, and its presence in landfill gas often necessitates the installation of expensive removal systems. For landfill operators to understand the cost of managing sulfur-containing wastes, an estimate of the H{sub 2}S production potential is needed. The objective of this study was to develop and demonstrate a biochemical sulfide potential (BSP) test to measure the amount of H{sub 2}S produced by different types of sulfur-containing wastes in a relatively fast (30 days) and inexpensive (125 mL serum bottles) batch assay. This study confirmed the toxic effect of H{sub 2}S on both sulfate reduction and methane production in batch systems, and demonstrated that removing accumulated H{sub 2}S by base adsorption was effective for mitigating inhibition. H{sub 2}S production potentials of coal combustion fly ash, flue gas desulfurization residual, municipal solid waste combustion ash, and construction and demolition waste were determined in BSP assays. After 30 days of incubation, most of the sulfate in the wastes was converted to gaseous or aqueous phase sulfide, with BSPs ranging from 0.8 to 58.8 mL H{sub 2}S/g waste, depending on the chemical composition of the samples. Selected samples contained solid phase sulfide which contributed to the measured H{sub 2}S yield. A 60 day incubation in selected samples resulted in 39–86% additional sulfide production. H{sub 2}S production measured in BSP assays was compared with that measured in simulated landfill reactors and that calculated from chemical analyses. H{sub 2}S production in BSP assays and in reactors was lower than the stoichiometric values calculated from chemical composition for all wastes tested, demonstrating

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.

Microstructure of laser floating zone (LFZ) textured (Bi,Pb)-Sr-Ca-Cu-O superconductor composites

International Nuclear Information System (INIS)

Fuente, G.F. de la; Ruiz, M.T.; Sotelo, A.; Larrea, A.; Navarro, R.

1993-01-01

Directionally solidified high temperature superconducting (Bi,Pb)-Sr-Ca-Cu-O pure ceramics and composites were obtained using a laser floating zone (LFZ) apparatus. The presence of secondary non-superconducting and metallic phases as well as their solidification habit have been analysed. The influence of the LFZ growth conditions and the precursor composition on the microstructure of the final products was studied using optical and electron microscopies. (orig.)

Radiographic observation and semi-analytical reconstruction of fracture process zone silicate composite specimen

Czech Academy of Sciences Publication Activity Database

Vavřík, Daniel; Jandejsek, Ivan; Fíla, Tomáš; Veselý, V.

2013-01-01

Roč. 58, č. 3 (2013), s. 315-326 ISSN 0001-7043 R&D Projects: GA ČR(CZ) GAP105/11/1551 Institutional support: RVO:68378297 Keywords : cementitious composite * quasi-brittle fracture * fracture process zone * digital radiography Subject RIV: JL - Materials Fatigue, Friction Mechanics http://journal.it.cas.cz/index.php?stranka=contents

Formation and Evolution of the Continental Lithospheric Mantle: Perspectives From Radiogenic Isotopes of Silicate and Sulfide Inclusions in Macrodiamonds

Science.gov (United States)

Shirey, S. B.; Richardson, S. H.

2007-12-01

Silicate and sulfide inclusions that occur in diamonds comprise the oldest (>3 Ga), deepest (>140 km) samples of mantle-derived minerals available for study. Their relevance to the evolution of the continental lithosphere is clear because terrestrial macrodiamonds are confined to regions of the Earth with continental lithospheric mantle keels. The goals of analytical work on inclusions in diamond are to obtain paragenesis constraints, radiogenic ages, and initial isotopic compositions. The purpose is to place diamond formation episodes into the broader framework of the geological processes that create and modify the continental lithosphere and to relate the source of the C and N in diamond-forming fluids to understanding the Earth's C and N cycles in the Archean. Although sulfide and silicate inclusions rarely occur in the same diamond, they both can be grouped according to their geochemical similarity with the chief rock types that comprise the mantle keel: peridotite and eclogite. Silicate inclusions are classified as harzburgitic (depleted; olivine > Fo91, garnet Cr2O3 > 3 wt% and CaO from 0 to 5 wt%), lherzolitic (fertile), or eclogitic (basaltic; garnet Cr2O3 14 wt%; Os > 2 ppm) versus eclogitic (Ni bearing kimberlites, and the generosity of mining companies because of the extreme rarity of inclusions in suites of mostly gem-quality diamonds. Most isotopic work has been on the Kaapvaal-Zimbabwe craton with lesser work on the Slave, Siberian, and Australian cratons. Sm-Nd ages on silicate suites and Re-Os ages on sulfide suites confirm diamond formation from the Mesoarchean though the Neoproterozoic. Most important are the systematics across cratons in the context of crustal geology that lead to generalities about craton evolution. Inclusion suites date mantle keels as Mesoarchean and clearly point to subduction as the major process to form the earliest continental nuclei and to amalgamate the cratons in their present form. This is evident from the elevated

Geologic setting and genesis of the Mule Canyon low-sulfidation epithermal gold-silver deposit, north-central Nevada

Science.gov (United States)

John, D.A.; Hofstra, A.H.; Fleck, R.J.; Brummer, J.E.; Saderholm, E.C.

2003-01-01

/or marcasite veins. Ore minerals consist mostly of electrum and Ag sulfide and selenide minerals, with minor to major amounts of pyrite, marcasite, and arsenopyrite, and local stibnite. Both types of ores have similar geochemical signatures, characterized by high Au, Ag, As, Sb, and Se contents, locally high Hg, Mo, Tl, and W contents, and low Cu, Pb, and Zn contents. Stable isotope data indicate that ore fluids consisted dominantly of meteoric water that evolved by deep circulation through Paleozoic sedimentary rocks at low water/rock ratios (about 1) and high temperatures (>200??C). Calculated isotopic compositions of ore fluids are ??18OH2O = -3 to -7 per mil, ??DH2O = -107 to -124 per mil, ??13CCO2 = 0 to -6 per mil, and ??34SH2S = -3 to +8 per mil. The ore fluids obtained much of their H2S and CO2 and probably scavenged ore metals and trace elements from the Paleozoic sedimentary rocks. Some H2S and CO2 may have been derived from degassing Miocene magmas. Mule Canyon formed at shallow depths, probably about 100 m below the paleosurface. Ore fluids were dilute, nearly neutral in pH, reduced, H2S-rich, and CO2-bearing. Peak temperatures in ore zones reached 230?? to 265??C at nearly lithostatic pressures when some crystalline quartz ?? adularia precipitated, but most ore formed at temperatures <200??C at near hydrostatic pressures and was accompanied by precipitation of opaline and chalcedonic silica ?? adularia ?? calcite and dolomite. Deposition of gold in As-rich overgrowths on pyrite and/or marcasite in disseminated ores occurred owing to decreasing H2S in the ore fluids resulting from sulfidation reactions. Later electrum and Ag selenide precipitation in open spaces occurred owing to boiling, loss of H2S to the vapor phase, and cooling. Mule Canyon is similar to most other low-sulfidation Au-Ag deposits associated with Miocene tholeiitic bimodal basalt-rhyolite magmatism in the Great Basin, such as Sleeper, Midas, and Buckhorn. Major differences at Mule Canyon are

Technetium behavior in sulfide and ferrous iron solutions

International Nuclear Information System (INIS)

Lee, S.Y.; Bondietti, E.A.

1982-01-01

Pertechnetate oxyanion ( 99 TcO 4- ), a potentially mobile species in leachate from a breached radioactive waste repository, was removed from a brine solution by precipitation with sulfide, iron, and ferrous sulfide at environmental pH's. Maghemite (ν-Fe 2 O 3 ) and geothite (α-FeOOH) were the dominant minerals in the precipitate obtained from the TcO 4- -ferrous iron reaction. The observation of small particle size and poor crystallinity of the minerals formed in the presence of Tc suggested that the Tc was incorporated into the mineral structure after reduction to a lower valence state. Amorphous ferrous sulfide, an initial phase precipitating in the TcO 4- -ferrous iron-sulfide reaction, was transformed to goethite and hematite (α-Fe 2 O 3 ) on aging. The black precipitate obtained from the TcO 4- -sulfide reaction was poorly crystallized technetium sulfide (Tc 2 S 7 ) which was insoluble in both acid and alkaline solution in the absence of strong oxidents. The results suggested that ferrous- and/or sulfide-bearing groundwaters and minerals in host rocks or backfill barriers could reduce the mobility of Tc through the formation of less-soluble Tc-bearing iron and/or sulfide minerals

Comparison of Polythionates as Precursors for the Formation of Thallium Sulfide Layers

Directory of Open Access Journals (Sweden)

Vitalijus JANICKIS

2011-11-01

Full Text Available The processes of obtaining layers of thallium, sulfides, TlxSy, by the sorption-diffusion method on polyamide 6 using solutions of lower polythionates - sodium trithionate and tetrathionate, Na2S3O6, Na2S4O6, potassium pentathionate, K2S5O6, and of dodecathionic acid, H2S12O6, as precursors of sulfur are compared. The concentration of sorbed sulfur increases with increasing the duration of treatment, the concentration and temperature of precursor solution. It rather significantly also depends on the nature - sulfurity of polythionate, i. e. on the number of sulfur atoms in the polythionate anion: effectiveness of sulfurization using solutions of dodecathionic acid is significantly higher than that of lower polythionates. Thallium sulfide layers are formed on the surface of polyamide after the treatment of sulfurized polymer with Tl(I salt solution. The concentration of thallium in the layer increases with the increase of initial sulfurization duration and in case of H2S12O6 solution used - on the temperature of this process. The results of X-ray diffraction analysis confirmed the formation of thallium sulfide layers in the surface of polyamide 6. The phase composition of layer changes depending on the conditions of initial treatment in a H2S12O6 solution. Five thallium sulfide phases, two forms of TlS, Tl2S2, Tl4S3 and Tl2S5 were identified in the composition of the layers treated for different time with a solution of dodecathionic acid at the temperature of 20 °C and 30 °C and then with Tl(I salt solution by X-ray diffraction but the maxima of TlS and Tl2S5 phases predominate in the diffractograms.http://dx.doi.org/10.5755/j01.ms.17.4.774

Chemical composition of aerosol in the atmospheric surface layer of the East Antarctica coastal zone

Directory of Open Access Journals (Sweden)

L. P. Golobokova

2016-01-01

Full Text Available Chemical composition of aerosol in the ground layer of the coastal zone in East Antarctica is analyzed in the article. The aerosol samples were taken in 2006–2015 during seasonal works of the Russian Antarctic Expeditions (RAE, namely, these were 52nd–53rd, 55th, and 58th–60th expeditions. Samples were taken in the 200‑km band of the sea-shore zone along routes of the research vessels (REV «Akademik Fedorov» and «Akademik Treshnikov» as well as on territories of the Russian stations Molodezhnaya and Mirny. Although the results obtained did show the wide range of the aerosol concentrations and a certain variability of their chemical composition, some common features of the variability were revealed. Thus, during the period from 2006 to 2014 a decrease of average values of the sums were noted. Spatially, a tendency of decreasing of the ion concentrations was found in the direction from the station Novolazarevskaya to the Molodezhnaya one, but the concentrations increased from the Molodezhnaya to the station Mirny. The sum of ions of the aerosol in the above mentioned coastal zone was, on the average, equal to 2.44 μg/m3, and it was larger than that on the territory of the Antarctic stations Molodezhnaya (0,29 μg/m3 and Mirny (0,50 ág / m3. The main part to the sum of the aerosol ions on the Antarctic stations was contributed by Na+, Ca2+, Cl−, SO4 2−. The main ions in aerosol composition in the coastal zone are ions Na+ and Cl−. The dominant contribution of the sea salt and SO4 2− can be traced in not only the composition of atmospheric aerosols, but also in the chemical composition of the fresh snow in the coastal areas of East Antarctica: at the Indian station Maitri, on the Larsemann Hills, and in a boring located in 55.3 km from the station Progress (K = 1.4÷6.1. It was noted that values of the coefficient of enrichment K of these ions decreases as someone moves from a shore to inland. Estimation of

Carbon steel protection in G.S. (Girlder sulfide) plants. Pressure influence on iron sulfide scales formation. Pt. 5

International Nuclear Information System (INIS)

Delfino, C.A.; Lires, O.A.; Rojo, E.A.

1987-01-01

In order to protect carbon steel towers and piping of Girlder sulfide (G.S.) experimental heavy water plants against corrosion produced by the action of aqueous solutions of hydrogen sulfide, a method, previously published, was developed. Carbon steel, exposed to saturated aqueous solutions of hydrogen sulfide, forms iron sulfide scales. In oxygen free solutions evolution of corrosion follows the sequence: mackinawite → cubic ferrous sulfide → troilite → pyrrotite → pyrite. Scales formed by pyrrotite-pyrite or pyrite are the most protective layers (these are obtained at 130 deg C, 2MPa, for periods of 14 days). Experiments, at 125 deg C and periods of 10-25 days, were performed in two different ways: 1- constant pressure operations at 0.5 and 1.1 MPa. 2- variable pressure operation between 0.3-1 MPa. In all cases pyrrotite-pyrite scales were obtained. (Author) [es

Potential for Sulfide Mineral Deposits in Australian Waters

Science.gov (United States)

McConachy, Timothy F.

The world is witnessing a paradigm shift in relation to marine mineral resources. High-value seafloor massive sulfides at active convergent plate boundaries are attracting serious commercial attention. Under the United Nations Convention on the Law of the Sea, maritime jurisdictional zones will increase by extending over continental margins and ocean basins. For Australia, this means a possible additional 3.37 million km2 of seabed. Australia's sovereign responsibility includes, amongst other roles, the management of the exploitation of nonliving resources and sea-bed mining. What, therefore, is the potential in Australia's marine jurisdiction for similar deposits to those currently attracting commercial attention in neighboring nations and for other types/styles of sulfide deposits? A preliminary review of opportunities suggests the following: (i) volcanogenic copper—lead—zinc—silver—gold mineralization in fossil arcs and back arcs in eastern waters Norfolk Ridge and the Three Kings Ridge; (ii) Mississippi Valley-type lead—zinc—silver mineralization in the NW Shelf area; (iii) ophiolite-hosted copper mineralization in the Macquarie Ridge Complex in the Southern Ocean; and (iv) submerged extensions of prospective land-based terranes, one example being offshore Gawler Craton for iron oxide—copper—gold deposits. These areas would benefit from pre-competitive surveys of detailed swath bathymetry mapping, geophysical surveys, and sampling to help build a strategic inventory of future seafloor mineral resources for Australia.

Sulfide oxidation and acid mine drainage formation within two active tailings impoundments in the Golden Quadrangle of the Apuseni Mountains, Romania.

Science.gov (United States)

Sima, Mihaela; Dold, Bernhard; Frei, Linda; Senila, Marin; Balteanu, Dan; Zobrist, Jurg

2011-05-30

Sulfidic mine tailings have to be classified as one of the major source of hazardous materials leading to water contamination. This study highlights the processes leading to sulfide oxidation and acid mine drainage (AMD) formation in the active stage of two tailings impoundments located in the southern part of the Apuseni Mountains, in Romania, a well-known region for its long-term gold-silver and metal mining activity. Sampling was undertaken when both impoundments were still in operation in order to assess their actual stage of oxidation and long-term behavior in terms of the potential for acid mine drainage generation. Both tailings have high potential for AMD formation (2.5 and 3.7 wt.% of pyrite equivalent, respectively) with lesser amount of carbonates (5.6 and 3.6 wt.% of calcite equivalent) as neutralization potential (ABA=-55.6 and -85.1 tCaCO(3)/1000 t ) and showed clear signs of sulfide oxidation yet during operation. Sequential extraction results indicate a stronger enrichment and mobility of elements in the oxidized tailings: Fe as Fe(III) oxy-hydroxides and oxides (transformation from sulfide minerals, leaching in oxidation zone), Ca mainly in water soluble and exchangeable form where gypsum and calcite are dissolved and higher mobility of Cu for Ribita and Pb for Mialu. Two processes leading to the formation of mine drainage at this stage could be highlighted (1) a neutral Fe(II) plume forming in the impoundment with ferrihydrite precipitation at its outcrop and (2) acid mine drainage seeping in the unsaturated zone of the active dam, leading to the formation of schwertmannite at its outcrop. Copyright © 2011 Elsevier B.V. All rights reserved.

Element enrichment and U-series isotopic characteristics of the hydrothermal sulfides at Jade site in the Okinawa Trough

Institute of Scientific and Technical Information of China (English)

无

2009-01-01

The geochemical and U-series isotopic characteristics of hydrothermal sulfide samples from the Jade site (127°04.5′E, 27°15′N, water depth 1300-1450 m) at Jade site in the Okinawa Trough were analyzed. In the hydrothermal sulfide samples bearing sulfate (samples HOK1 and HOK2), the LREEs are relatively enriched. All the hydrothermal sulfide samples except HOK1 belong to Zn-rich hydrothermal sulfide. In comparison with Zn-rich hydrothermal sulfides from other fields, the contents of Zn, Pb, Ag, Cd, Au and Hg are higher, the contents of Fe, Al, Cr, Co, Ni, Sr, Te, Cs, Ti and U lower, and the 210Pb radioactivity ratios and 210Pb/Pb ratios very low. In the hydrothermal sulfide mainly composed of sphalerite, the correlations between rare elements Hf and U, and Hf and Mn as well as that between dispersive elements Ga and Zn, are strongly positive; also the contents of Au and Ag are related to Fe-sulfide, because the low temperature promotes enrichment of Au and Ag. Meanwhile, the positive correlations between Fe and Bi and between Zn and Cd are not affected by the change of mineral assemblage. Based on the 210Pb/Pb ratios of hydrothermal sulfide samples (3.99×10-5-5.42×10?5), their U isotopic composition (238U content 1.15-2.53 ppm, 238U activity 1.07-1.87 dpm/g, 234U activity 1.15-2.09 dpm/g and 234U/238U ratio 1.07-1.14) and their 232Th and 230Th contents are at base level, and the chronological age of hydrothermal sulfide at Jade site in the Okinawa Trough is between 200 and 2000 yr.

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

Integrated 3D Geological Modeling to Gain Insight in the Effects of Hydrothermal Alteration on Post-Ore Deformation Style and Strain Localization in the Flin Flon Volcanogenic Massive Sulfide Ore System

Directory of Open Access Journals (Sweden)

Ernst Schetselaar

2017-12-01

Full Text Available 3D geological modeling of lithogeochemical and geological data provides insight into the role of the sulfide ore horizon and associated footwall hydrothermal alteration in localizing shear strain in the Flin Flon volcanogenic massive sulfide deposits, Canada, as deformation evolved from brittle-ductile to ductile regimes during collisional stages of the 1.9–1.8 Ga Trans-Hudson orogeny. 3D spatial characterization of hydrothermal alteration based on the Ishikawa index (AI and normative corundum percentages outline sericite + chlorite-rich high strain zones, consisting of Al-enriched and Na-depleted felsic and mafic volcanic rocks in the footwall of the sulfide ore horizon. The hydrothermal vent complex, from which these sheared alteration zones originated, was stacked together with the ore horizon by W-vergent thrust faults during an early collisional deformation regime, imbricating molasse-type clastic sediments with the ore-hosting volcanic and volcaniclastic rocks of the Flin Flon arc assemblage. Chlorite-rich planar zones marked by high values of the Carbonate–chlorite–pyrite index (CCPI are laterally more extensive and outline a later system of ductile shear zones, in which phyllosilicates, quartz and chalcopyrite in stringer zones localized shear strain and enhanced transposition of the hydrothermal vent stockwork. The contrasting deformation styles of these two thrusting events and their localization within the ore horizon and hydrothermal vent stockwork have important implications for vectoring towards undiscovered ore in this mature mining camp that are possibly also relevant to other strongly deformed VMS ore systems.

Band offset in zinc oxy-sulfide/cubic-tin sulfide interface from X-ray photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Sanal, K.C.; Nair, P.K.; Nair, M.T.S., E-mail: mtsn@ier.unam.mx

2017-02-28

Highlights: • Zinc oxy-sulfide thin films, 175–240 nm, deposited by rf-sputtering from targets of ZnO + ZnS. • Oxygen content in thin films is enhanced 3–4 times compared with that in ZnO:ZnS targets. • Thin film ZnO{sub x}S{sub 1−x} with x = 0.88–0.27 and optical band gap 2.8–3.2 eV is suitable for solar cells. • The conduction band offset with SnS of cubic structure studied by XPS are +0.41 to −0.28 eV. - Abstract: Zinc oxy-sulfide, ZnO{sub x}S{sub 1−x}, has been found to provide better band alignment in thin film solar cells of tin sulfide of orthorhombic crystalline structure. Here we examine ZnO{sub x}S{sub 1−x}/SnS-CUB interface, in which the ZnO{sub x}S{sub 1−x} thin film was deposited by radio frequency (rf) magnetron sputtering on SnS thin film of cubic (CUB) crystalline structure with a band gap (E{sub g}) of 1.72 eV, obtained via chemical deposition. X-ray photoelectron spectroscopy provides the valence band maxima of the materials and hence places the conduction band offset of 0.41 eV for SnS-CUB/ZnO{sub 0.27}S{sub 0.73} and −0.28 eV for SnS-CUB/ZnO{sub 0.88}S{sub 0.12} interfaces. Thin films of ZnO{sub x}S{sub 1−x} with 175–240 nm in thickness were deposited from targets prepared with different ZnO to ZnS molar ratios. With the target of molar ratio of 1:13.4, the thin films are of composition ZnO{sub 0.27}S{sub 0.73} with hexagonal crystalline structure and with that of 1:1.7 ratio, it is ZnO{sub 0.88}S{sub 0.12}. The optical band gap of the ZnO{sub x}S{sub 1−x} thin films varies from 2.90 eV to 3.21 eV as the sulfur to zinc ratio in the film increases from 0.12:1 to 0.73:1 as determined from X-ray diffraction patterns. Thus, band offsets sought for absorber materials and zinc oxy-sulfide in solar cells may be achieved through a choice of ZnO:ZnS ratio in the sputtering target.

Adsorption of sulfide ions on cerussite surfaces and implications for flotation

International Nuclear Information System (INIS)

Feng, Qicheng; Wen, Shuming; Zhao, Wenjuan; Deng, Jiushuai; Xian, Yongjun

2016-01-01

Highlights: • A new discussion on the lead sulfide species is introduced. • The Na_2S concentration determines cerussite sulfidization. • The activity of lead sulfide species also determines cerussite sulfidization. • Disulfide and polysulfide in lead sulfide species affect its activity. - Abstract: The adsorption of sulfide ions on cerussite surfaces and implications for flotation were studied by X-ray photoelectron spectroscopy (XPS) analysis, micro-flotation tests, and surface adsorption experiments. The XPS analysis results indicated that lead sulfide species formed on the mineral surface after treatment by Na_2S, and the increase in the Na_2S concentration was beneficial for sulfidization. In addition to the content of lead sulfide species, its activity, which was determined by the proportion of sulfide, disulfide and polysulfide, also played an important role in cerussite sulfidization. Micro-flotation tests results demonstrated that insufficient or excessive addition of Na_2S in pulp solutions has detrimental effects on flotation performance, which was attributed to the dosage of Na_2S and the activity of lead sulfide species formed on the mineral surface. Surface adsorption experiments of sulfide ions determined the residual S concentrations in pulp solutions and provided a quantitative illustration for the inhibition of cerussite flotation by excessive sulfide ions. Moreover, it also revealed that sulfide ions in the pulp solution were transformed onto the mineral surface and formed lead sulfide species. These results showed that both of lead sulfide species and its activity acted as an important role in sulfidization flotation process of cerussite.

Adsorption of sulfide ions on cerussite surfaces and implications for flotation

Energy Technology Data Exchange (ETDEWEB)

Feng, Qicheng [State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming 650093 (China); Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Wen, Shuming, E-mail: fqckmust@126.com [State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming 650093 (China); Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Zhao, Wenjuan [Kunming Metallurgical Research Institute, Kunming 650031 (China); Deng, Jiushuai; Xian, Yongjun [State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming 650093 (China); Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093 (China)

2016-01-01

Highlights: • A new discussion on the lead sulfide species is introduced. • The Na{sub 2}S concentration determines cerussite sulfidization. • The activity of lead sulfide species also determines cerussite sulfidization. • Disulfide and polysulfide in lead sulfide species affect its activity. - Abstract: The adsorption of sulfide ions on cerussite surfaces and implications for flotation were studied by X-ray photoelectron spectroscopy (XPS) analysis, micro-flotation tests, and surface adsorption experiments. The XPS analysis results indicated that lead sulfide species formed on the mineral surface after treatment by Na{sub 2}S, and the increase in the Na{sub 2}S concentration was beneficial for sulfidization. In addition to the content of lead sulfide species, its activity, which was determined by the proportion of sulfide, disulfide and polysulfide, also played an important role in cerussite sulfidization. Micro-flotation tests results demonstrated that insufficient or excessive addition of Na{sub 2}S in pulp solutions has detrimental effects on flotation performance, which was attributed to the dosage of Na{sub 2}S and the activity of lead sulfide species formed on the mineral surface. Surface adsorption experiments of sulfide ions determined the residual S concentrations in pulp solutions and provided a quantitative illustration for the inhibition of cerussite flotation by excessive sulfide ions. Moreover, it also revealed that sulfide ions in the pulp solution were transformed onto the mineral surface and formed lead sulfide species. These results showed that both of lead sulfide species and its activity acted as an important role in sulfidization flotation process of cerussite.

Recolonization of macrozoobenthos on defaunated sediments in a hypertrophic brackish lagoon: effects of sulfide removal and sediment grain size.

Science.gov (United States)

Kanaya, Gen

2014-04-01

Influences of sediment types on recolonization of estuarine macrozoobenthos were tested using enclosures in a hypertrophic lagoon. Three types of azoic sediment, sand (S), sulfide-rich mud (M), and mud removed of sulfide through iron addition (MFe), were set in field for 35 days during a hypoxic period. A total of 14 taxa including opportunistic polychaetes and amphipods occurred. Infaunal community in S treatment was characterized by highest diversity, total density and biomass, and population density of five dominant taxa, while those parameters were lowest in M treatment. Sulfide removal in MFe treatment achieved much higher density, biomass, and population densities of several taxa in the sediment. Multivariate analyses demonstrated that the established community structure was unique to each treatment. These imply that dissolved sulfide level as well as sediment grain size is a key determinant for the community composition and recolonization speed of early colonists in estuarine soft-bottom habitats. Copyright © 2014 Elsevier Ltd. All rights reserved.

Indium sulfide buffer layers deposited by dry and wet methods

International Nuclear Information System (INIS)

Asenjo, B.; Sanz, C.; Guillen, C.; Chaparro, A.M.; Gutierrez, M.T.; Herrero, J.

2007-01-01

Indium sulfide (In 2 S 3 ) thin films have been deposited on amorphous glass, glass coated by tin oxide (TCO) and crystalline silicon substrates by two different methods: modulated flux deposition (MFD) and chemical bath deposition (CBD). Composition, morphology and optical characterization have been carried out with Scanning Electron Microscopy (SEM), IR-visible-UV Spectrophotometry, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectrometer. Different properties of the films have been obtained depending on the preparation techniques. With MFD, In 2 S 3 films present more compact and homogeneous surface than with CBD. Films deposited by CBD present also indium oxide in their composition and higher absorption edge values when deposited on glass

A Cryptic Sulfur Cycle in Oxygen-Minimum-Zone Waters off the Chilean Coast

Science.gov (United States)

Canfield, Don E.; Stewart, Frank J.; Thamdrup, Bo; De Brabandere, Loreto; Dalsgaard, Tage; Delong, Edward F.; Revsbech, Niels Peter; Ulloa, Osvaldo

2010-12-01

Nitrogen cycling is normally thought to dominate the biogeochemistry and microbial ecology of oxygen-minimum zones in marine environments. Through a combination of molecular techniques and process rate measurements, we showed that both sulfate reduction and sulfide oxidation contribute to energy flux and elemental cycling in oxygen-free waters off the coast of northern Chile. These processes may have been overlooked because in nature, the sulfide produced by sulfate reduction immediately oxidizes back to sulfate. This cryptic sulfur cycle is linked to anammox and other nitrogen cycling processes, suggesting that it may influence biogeochemical cycling in the global ocean.

Wüstite in the fusion crust of Almahata Sitta sulfide-metal assemblage MS-166: Evidence for oxygen in metallic melts

Science.gov (United States)

Horstmann, Marian; Humayun, Munir; Harries, Dennis; Langenhorst, Falko; Chabot, Nancy L.; Bischoff, Addi; Zolensky, Michael E.

2013-05-01

Meteorite fusion crusts form during the passage of a meteoroid through the Earth's atmosphere and are highly oxidized intergrowths as documented by the presence of e.g., oxides. The porous and irregular fusion crust surrounding the Almahata Sitta sulfide-metal assemblage MS-166 was found highly enriched in wüstite (Fe1-xO). Frictional heating of the outer portions of the assemblage caused partial melting of predominantly the Fe-sulfide and minor amounts of the outer Ni-rich portions of the originally zoned metal in MS-166. Along with melting significant amounts of oxygen were incorporated into the molten fusion crust and mainly FeS was oxidized and desulfurized to form wüstite. Considerable amounts of FeS were lost due to ablation, whereas the cores of the large metal grains appear largely unmelted leaving behind metal grains and surrounding wüstite-rich material (matte). Metal grains along with the surrounding matte typically form an often highly porous framework of globules interconnected with the matte. Although textures and chemical composition suggest that melting of Fe,Ni metal occurred only partially (Ni-rich rims), there is a trace elemental imprint of siderophile element partitioning influenced by oxygen in the metallic melt as indicated by the behavior of W and Ga, the two elements significantly affected by oxygen in a metallic melt. It is remarkable that MS-166 survived the atmospheric passage as troilite inclusions in iron meteorites are preferentially destroyed.

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.

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

Effect of lighting conditions of coastal zone of Knyaginya lake on composition of macrophyte biohydrocenoses

Directory of Open Access Journals (Sweden)

B. O. Baranovsky

2005-10-01

Full Text Available In articlе the stuffs of researches of influence of a mode of illuminating intensity of coastal zone of a different exposition flood-land of lake Knyaginya (valley Samara on composition of highest aqueous green and macrozoobentos macrophytes biogeocenose are submitted.

Microaeration for hydrogen sulfide removal in UASB reactor.

Science.gov (United States)

Krayzelova, Lucie; Bartacek, Jan; Kolesarova, Nina; Jenicek, Pavel

2014-11-01

The removal of hydrogen sulfide from biogas by microaeration was studied in Up-flow Anaerobic Sludge Blanket (UASB) reactors treating synthetic brewery wastewater. A fully anaerobic UASB reactor served as a control while air was dosed into a microaerobic UASB reactor (UMSB). After a year of operation, sulfur balance was described in both reactors. In UASB, sulfur was mainly presented in the effluent as sulfide (49%) and in biogas as hydrogen sulfide (34%). In UMSB, 74% of sulfur was detected in the effluent (41% being sulfide and 33% being elemental sulfur), 10% accumulated in headspace as elemental sulfur and 9% escaped in biogas as hydrogen sulfide. The efficiency of hydrogen sulfide removal in UMSB was on average 73%. Microaeration did not cause any decrease in COD removal or methanogenic activity in UMSB and the elemental sulfur produced by microaeration did not accumulate in granular sludge. Copyright © 2014 Elsevier Ltd. All rights reserved.

Hydrogen sulfide-powered solid oxide fuel cells

Science.gov (United States)

Liu, Man

2004-12-01

The potential utilization of hydrogen sulfide as fuel in solid oxide fuel cells has been investigated using an oxide-ion conducting YSZ electrolyte and different kinds of anode catalysts at operating temperatures in the range of 700--900°C and at atmospheric pressure. This technology offers an economically attractive alternative to present methods for removing toxic and corrosive H2S gas from sour gas streams and a promising approach for cogenerating electrical energy and useful chemicals. The primary objective of the present research was to find active and stable anode materials. Fuel cell experimental results showed that platinum was a good electrocatalyst for the conversion of H2S, but the Pt/YSZ interface was physically unstable due to the reversible formation and decomposition of PtS in H 2S streams at elevated temperatures. Moreover, instability of the Pt/YSZ interface was accelerated significantly by electrochemical reactions, and ultimately led to the detachment of the Pt anode from the electrolyte. It has been shown that an interlayer of TiO2 stabilized the Pt anode on YSZ electrolyte, thereby prolonging cell lifetime. However, the current output for a fuel cell using Pt/TiO2 as anode was not improved compared to using Pt alone. It was therefore necessary to investigate novel anode systems for H 2S-air SOFCs. New anode catalysts comprising composite metal sulfides were developed. These catalysts exhibited good electrical conductivity and better catalytic activity than Pt. In contrast to MoS2 alone, composite catalysts (M-Mo-S, M = Fe, Co, Ni) were not volatile and had superior stability. However, when used for extended periods of time, detachment of Pt current collecting film from anodes comprising metal sulfides alone resulted in a large increase in contact resistance and reduction in cell performance. Consequently, a systematic investigation was conducted to identify alternative electronic conductors for use with M-Mo-S catalysts. Anode catalysts

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.

Sulfide Precipitation in Wastewater at Short Timescales

DEFF Research Database (Denmark)

Kiilerich, Bruno; van de Ven, Wilbert; Nielsen, Asbjørn Haaning

2017-01-01

Abatement of sulfides in sewer systems using iron salts is a widely used strategy. When dosing at the end of a pumping main, the reaction kinetics of sulfide precipitation becomes important. Traditionally the reaction has been assumed to be rapid or even instantaneous. This work shows that this i......Abatement of sulfides in sewer systems using iron salts is a widely used strategy. When dosing at the end of a pumping main, the reaction kinetics of sulfide precipitation becomes important. Traditionally the reaction has been assumed to be rapid or even instantaneous. This work shows...... that this is not the case for sulfide precipitation by ferric iron. Instead, the reaction time was found to be on a timescale where it must be considered when performing end-of-pipe treatment. For real wastewaters at pH 7, a stoichiometric ratio around 14 mol Fe(II) (mol S(−II))−1 was obtained after 1.5 s, while the ratio...

As, Bi, Hg, S, Sb, Sn and Te geochemistry of the J-M Reef, Stillwater Complex, Montana: constraints on the origin of PGE-enriched sulfides in layered intrusions

Science.gov (United States)

Zientek, M.L.; Fries, T.L.; Vian, R.W.

1990-01-01

The J-M Reef is an interval of disseminated sulfides in the Lower Banded series of the Stillwater Complex that is enriched in the platinum group elements (PGE). Palladium and Pt occur in solid solution in base-metal sulfides and as discrete PGE minerals. PGE minerals include sulfides, tellurides, arsenides, antimonides, bismuthides, and alloys with Fe, Sn, Hg, and Au. Several subpopulations can be delineated based on whole-rock chemical analyses for As, Bi, Cu, Hg, Pd, Pt, S, Sb and Te for samples collected from and adjacent to the J-M Reef. In general, samples from within the reef have higher Pt/Cu, Pd/Cu, Pd/Pt, Te/Bi and S/(Te+Bi) than those collected adjacent to the reef. Vertical compositional profiles through the reef suggest that Pd/Cu and Pt/Cu decrease systematically upsection from mineralized to barren rock. The majority of samples with elevated As, Sb and Hg occur adjacent to the reef, not within it, or in sulfide-poor rocks. Neither magma mixing nor fluid migration models readily explain why the minor quantities of sulfide minerals immediately adjacent to the sulfide-enriched layers that form the J-M Reef have different element ratios than the sulfide minerals that form the reef. If all the sulfides formed by exsolution during a magma mixing event and the modal proportion of sulfide now in the rocks are simply the result of mechanical processes that concentrated the sulfides into some layers and not others, then the composition of the sulfide would not be expected to be different. Models that rely upon ascending liquids or fluids are incompatible with the presence of sulfides that are not enriched in PGE immediately below or interlayered with the PGE-enriched sulfides layers. PGE-enriched postcumulus fluids should have reacted to the same extent with sulfides immediately outside the reef as within the reef. One explanation is that some of the sulfide minerals in the rocks outside the reef have a different origin than those that make up the reef. The

Ultrafine Cobalt Sulfide Nanoparticles Encapsulated Hierarchical N-doped Carbon Nanotubes for High-performance Lithium Storage

International Nuclear Information System (INIS)

Li, Xiaoyan; Fu, Nianqing; Zou, Jizhao; Zeng, Xierong; Chen, Yuming; Zhou, Limin; Lu, Wei; Huang, Haitao

2017-01-01

Graphical abstract: Ultrafine cobalt sulfide nanoparticles encapsulated in hierarchical N-doped carbon nanotubes show exceptional lithium ion storage as anodes. - Abstract: Nanostructured cobalt sulfide based materials with rational design are attractive for high-performance lithium-ion batteries. In this work, we report a multistep method to synthesize ultrafine cobalt sulfide nanoparticles encapsulated in hierarchical N-doped carbon nanotubes (CoS x @HNCNTs). Co-based zeolitic imidazolate framework (ZIF-67) nanotubes are obtained from the reaction between electrospun polyacrylonitrile/cobalt acetate and 2-methylimidazole, followed by the dissolution of template. Next, a combined calcination and sulfidation process is employed to convert the ZIF-67 nanotubes to CoS x @HNCNTs. Benefited from the compositional and structural features, the as-prepared nanostructured hybrid materials deliver superior lithium storage properties with high capacity of 1200 mAh g −1 at 0.25 A g −1 . More importantly, a remarkable capacity of 1086 mAh g −1 can be maintained after 100 cycles at the current density of 0.5 A g −1 . Even at a high rate of 5 A g −1 , a reversible capacity of 592 mAh g −1 after 1600 cycles can still be achieved.

Organic-inorganic hybrid polyionic liquid based polyoxometalate as nano porous material for selective oxidation of sulfides

Science.gov (United States)

Rafiee, Ezzat; Shahebrahimi, Shabnam

2017-07-01

Organic-inorganic hybrid nano porous materials based on poly(ionic liquid)-polyoxometalate (PIL-POM) were reported. These hybrid materials were synthesized by the reaction of 4-vinyl pyridine with 1,3-propanesultone, followed by the polymerization and also sulfonate-functionalized cross-linked poly(4-vinylpyridine) and combining these polymers with H5PMo10V2O40 (PMo10V2). Activity of prepared PIL-PMo10V2 hybrids were investigated as catalysts for oxidation of sulfides with H2O2 as oxidant. For understanding catalytic activities of the PIL-PMo10V2 hybrids in oxidation of sulfides, effect of catalyst composition, substrate, and reaction conditions were studied. The results show that the PIL-PMo10V2 hybrids are active as selective heterogeneous catalysts for oxidation of sulfides and can be recovered and reused. The catalyst was characterized by FT-IR, TGA-DSC, XRD, SEM/EDX, BET, CV and zeta potential measurement. Also, average molecular weight of prepared catalysts were measured.

Sulfide-conducting solid electrolytes

International Nuclear Information System (INIS)

Kalinina, L.A.; Shirokova, G.I.; Murin, I.V.; Ushakova, Yu.N.; Fominykh, E.G.; Lyalina, M.Yu.

2000-01-01

Feasibility of sulfide transfer in phases on the basis of BaZrS 3 and MLn 2 S 4 ( M = Ca, Ba; Ln = La, Y, Tm, Nd, Sm, Pr) is considered. Solid solution regions on the basis of ternary compounds are determined. Systematic study of the phases is carried out making use of the methods of conductometry, emf in chemical concentration chains without/with transfer, potentiostatic chronoamperometry. Possible mechanism of defect formation during successive alloying of ternary sulfides by binary ones in suggested [ru

A study on the composition of off-odor volatiles in irradiated pork

International Nuclear Information System (INIS)

Lin Ruotai; Geng Shengrong; Zhang Jinmu; Chen Yuxia; Liu Yangmin; Wang Liping; Wang Hong; Xu Ying; Yao Side

2006-01-01

The purpose of this study was to lay a foundation on generation mechanisms and removal method of off-odor of irradiated meat products. Vacuum-package and refrigerated raw pork samples were irradiated with 60 Co γ-rays. Off-odor volatiles from the irradiated pork samples were taken in by a vacuum system and were collected by a cooled vial in liquid nitrogen. At the same time, the source of off-odor generation was investigated. Main compositions of off-odor volatiles of the irradiated pork were analyzed with gas chromatograph mass spectrometry (GC-MS). The results showed that main compositions of the off-odor volatiles were dimethyl disulfide, dimethyl sulfide, dimethyl trisulfide, methanethiol and S-methyl thioacetate, and the off-odor volatiles came from sulfide-containing amino acid and thiamin of the irradiated pork. Sulfide-containing compounds increased with the dose in the range of 0-3 kGy, and decreased with the refrigeration time, but changed from different kinds of the package. The non-irradiated samples, however, contained just a little sulfide-containing compounds of dimethyl sulfide and vangardbt. (authors)

Gold contents of sulfide minerals in granitoids from southwestern New Brunswick, Canada

Science.gov (United States)

Yang, Xue-Ming; Lentz, David R.; Sylvester, Paul J.

2006-07-01

The abundance of gold and selected trace elements in magmatic sulfide and rock-forming minerals from Silurian-Devonian granitoids in southwestern New Brunswick were quantitatively analyzed by laser-ablation inductively coupled plasma mass-spectrometry. Gold is mainly hosted in sulfide minerals (i.e., chalcopyrite, pyrrhotite, and pyrite), in some cases perhaps as submicron inclusions (nanonuggets). Gold is below detection (caca % qGTbGaaeyzaiaabYgacaqG0baaaOGaeyypa0JaaGymaiaaiwdacaaI % WaGaeyySaeRaaGioaiaaiodacaGGSaGaaeiiaiaabggacaqGUbGaae % izaiaabccacaWGebWaa0baaSqaaiaabgeacaqG1baabaGaaeiCaiaa % bMhacaqGVaGaaeyBaiaabwgacaqGSbGaaeiDaaaakiabg2da9iaaio % dacaaI2aGaaGOmaiabgglaXkaaiMdacaaI2aaaaa!6E8F! D^{{{text{cpy/melt}}}}_{{{text{Au}}}}= 948 ± 269,{text{ }}D^{{{text{po/melt}}}}_{{{text{Au}}}} = 150 ± 83,{text{ and }}D^{{{text{py/melt}}}}_{{{text{Au}}}} = 362 ± 96. This result suggests that gold behavior in the granitoid systems is controlled by the conditions of sulfur saturation during magmatic evolution; the threshold of physiochemical conditions for sulfur saturation in the melts is a key factor affecting gold activity. Gold behaves incompatibly prior to the formation of sulfide liquids or minerals, but it becomes compatible at their appearance. Gold would be enriched in sulfur-undersaturated granitoid magmas during fractionation, partitioning into evolved magmatic fluids and favoring the formation of intrusion-related gold deposits. However, gold becomes depleted in residual melts if these melts become sulfur-saturated during differentiation, leading to gold precipitation in the early sulfide phases of a granitoid suite. Late-stage Cl-bearing magmatic-hydrothermal fluids with low pH and relatively high oxidation state derived from either progressively cooling magmas at depth or convective circulation of meteoric water buffered by reduced carbon-bearing sediments, may scavenge gold from early sulfide minerals. If a significant amount of gold produced in this

Anoxic sulfide biooxidation using nitrite as electron acceptor

International Nuclear Information System (INIS)

Mahmood, Qaisar; Zheng Ping; Cai Jing; Wu Donglei; Hu, Baolan; Li Jinye

2007-01-01

Biotechnology can be used to assess the well being of ecosystems, transform pollutants into benign substances, generate biodegradable materials from renewable sources, and develop environmentally safe manufacturing and disposal processes. Simultaneous elimination of sulfide and nitrite from synthetic wastewaters was investigated using a bioreactor. A laboratory scale anoxic sulfide-oxidizing (ASO) reactor was operated for 135 days to evaluate the potential for volumetric loading rates, effect of hydraulic retention time (HRT) and substrate concentration on the process performance. The maximal sulfide and nitrite removal rates were achieved to be 13.82 and 16.311 kg/(m 3 day), respectively, at 0.10 day HRT. The process can endure high sulfide concentrations, as the sulfide removal percentage always remained higher than 88.97% with influent concentration up to 1920 mg/L. Incomplete sulfide oxidation took place due to lower consumed nitrite to sulfide ratios of 0.93. It also tolerated high nitrite concentration up to 2265.25 mg/L. The potential achieved by decreasing HRT at fixed substrate concentration is higher than that by increasing substrate concentration at fixed HRT. The process can bear short HRT of 0.10 day but careful operation is needed. Nitrite conversion was more sensitive to HRT than sulfide conversion when HRT was decreased from 1.50 to 0.08 day. Stoichiometric analyses and results of batch experiments show that major part of sulfide (89-90%) was reduced by nitrite while some autooxidation (10-11%) was resulted from presence of small quantities of dissolved oxygen in the influent wastewater. There was ammonia amassing in considerably high amounts in the bioreactor when the influent nitrite concentration reached above 2265.25 mg/L. High ammonia concentrations (200-550 mg/L) in the bioreactor contributed towards the overall inhibition of the process. Present biotechnology exhibits practical value with a high potential for simultaneous removal of nitrite

Particle Surface Hydrophobicity and the Dechlorination of Chloro-Compounds by Iron Sulfides

Energy Technology Data Exchange (ETDEWEB)

Park, Sang-Won, E-mail: spark3@uncc.edu; Kim, Sung-Kuk; Kim, Jeong-Bae; Choi, Sung-Woo [Keimyung University, Department of Environmental Science and Engineering (Korea, Republic of); Inyang, Hilary I. [University of North Carolina at Charlotte, Global Institute for Energy and Environmental Systems (United States); Tokunaga, Shuzo [National Institute of Advanced Industrial Science and Technology (Japan)

2006-02-15

Halogenated aliphatic compounds (HACs) can be reduced by iron sulfides in aqueous systems. Generally, the thermodynamics and kinetics of dehalogenation reactions are controlled by the mineralogical and particle surface characteristics of the iron sulfide, the composition of the HAC and reaction conditions such as component concentrations, pH and Eh. In this theoretical and experimental investigation of CCl{sub 4} and C{sub 2}Cl{sub 6} reduction by FeS and FeS{sub 2}, the roles of hydrophobic and hydrophilic sites on the iron sulfides were analyzed. Experimental data obtained through zeta potential measurements, were used along with the Gouy-Chapman model and the simple two-layer surface complexation model to relate iron sulfide surface hydroxyl densities to the degree of HAC dehalogenation. The surface hydroxyl site densities of FeS and FeS{sub 2} were found to be 0.11 sites/nm{sup 2} and 0.21 sites/nm{sup 2}, respectively. During the dehalogenation reaction process, CCl{sub 4} was found to decrease to its first intermediate product CHCl{sub 3} within the first 20 hours followed by a slower process of conversion to CH{sub 2}Cl{sub 2}. The results also show that FeS is less hydrated (more hydrophobic) than FeS{sub 2}. For CCl{sub 4} and C{sub 2}Cl{sub 6}, FeS is a better dehalogenator than FeS{sub 2}. These results imply that particle surface hydrophobicity is a critical factor in surface-mediated dehalogenation of chlorinated compounds.

Oxidation and Precipitation of Sulfide in Sewer Networks

DEFF Research Database (Denmark)

Nielsen, A. H.

risks and corrosion of concrete and metals. Most of the problems relate to the buildup of hydrogen sulfide in the atmosphere of sewer networks. In this respect, the processes of the sulfur cycle are of fundamental importance in ultimately determining the extent of such problems. This study focused...... 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...... to the sewer atmosphere, potentially resulting in concrete corrosion. The extended WATS model represents a major improvement over previously developed models for prediction of sulfide buildup in sewer networks. Compared to such models, the major processes governing sulfide buildup in sewer networks...

Kinetic Spectrophotometric Determination of Trace Amounts of Sulfide

Energy Technology Data Exchange (ETDEWEB)

Barzegar, Mohsen [Tarbiat Modarres University, Tehran (Iran, Islamic Republic of); Jabbari, Ali [K. N. Toosi University, Tehran (Iran, Islamic Republic of); Esmaeili, Majid [Razi University, Kermanshah (Iran, Islamic Republic of)

2003-09-15

A method for the determination of trace amount of sulfide based on the addition reaction of sulfide with methyl green at pH 7.5 and 25 .deg. C is described. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of the dyestuff at 637 nm by the initial rate and fixed time method. The calibration graph is linear in the range 30-1200 ppb. The theoretical limit of detection was 0.014 ppm. Seven replicate analysis of a sample solution containing 0.70 ppm sulfide gave a relative standard deviation of 1.5%. The interfering effects of various ions on sulfide determination have been reported and procedures for removal of interference have been described. The proposed method was applied successfully to the determination of sulfide in tap and wastewater samples.

Kinetic Spectrophotometric Determination of Trace Amounts of Sulfide

International Nuclear Information System (INIS)

Barzegar, Mohsen; Jabbari, Ali; Esmaeili, Majid

2003-01-01

A method for the determination of trace amount of sulfide based on the addition reaction of sulfide with methyl green at pH 7.5 and 25 .deg. C is described. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of the dyestuff at 637 nm by the initial rate and fixed time method. The calibration graph is linear in the range 30-1200 ppb. The theoretical limit of detection was 0.014 ppm. Seven replicate analysis of a sample solution containing 0.70 ppm sulfide gave a relative standard deviation of 1.5%. The interfering effects of various ions on sulfide determination have been reported and procedures for removal of interference have been described. The proposed method was applied successfully to the determination of sulfide in tap and wastewater samples

LIGNOCELLULOSE NANOCOMPOSITE CONTAINING COPPER SULFIDE

OpenAIRE

Sanchi Nenkova; Peter Velev; Mirela Dragnevska; Diyana Nikolova; Kiril Dimitrov

2011-01-01

Copper sulfide-containing lignocellulose nanocomposites with improved electroconductivity were obtained. Two methods for preparing the copper sulfide lignocellulose nanocomposites were developed. An optimization of the parameters for obtaining of the nanocomposites with respect to obtaining improved electroconductivity, economy, and lower quantities and concentration of copper and sulfur ions in waste waters was conducted. The mechanisms and schemes of delaying and subsequent connection of co...

Deposition of copper indium sulfide on TiO2 nanotube arrays and its application for photocatalytic decomposition of gaseous IPA

Directory of Open Access Journals (Sweden)

Young Ku

2016-09-01

Full Text Available TiO2 nanotube arrays (TNTs were modified with copper indium sulfide (Cu/In/S by successive ionic layer adsorption and reaction (SILAR method. The field-emission scanning electron microscopy and X-ray photoelectron spectroscopy analysis demonstrated the presence of copper indium sulfide nanoparticles on the surface of the modified TNTs. The Cu/In/S-modified TNTs exhibited higher photocurrent density and photocatalytic activity than plain TNTs. The concentration of sulfur precursor was found to be an important factor on the composition of modified Cu/In/S films by SILAR. Some composition deviations were observed on the stoichiometry of the Cu/In/S-modified TNTs, which evidently affected the electrochemical characteristics of the modified TNTs. Experiments using the modified TNTs of composition close to the stoichiometric ratio of CuInS2 usually delivered higher photocatalytic decomposition of gaseous isopropyl alcohol in air streams and exhibited better stability during operation.

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

Catalytic oxidation of sulfide in drinking water treatment: activated carbon as catalyst; Katalytische Oxidation von Sulfid bei der Trinkwasseraufbereitung: Aktivkohle als Katalysator

Energy Technology Data Exchange (ETDEWEB)

Hultsch, V; Grischek, T; Wolff, D; Worch, E [Technische Univ. Dresden (Germany). Inst. fuer Wasserchemie; Gun, J [Hebrew Univ. of Jerusalem (Israel). Div. of Environmental Sciences, Fredy and Nadine Herrmann School of Applied Science

2001-07-01

In regions with warm climate and limited water resources high sulfide concentrations in groundwater can cause problems during drinking water treatment. Aeration of the raw water is not always sufficient to ensure the hydrogen sulfide concentration below the odour threshold value for hydrogen sulfide. As an alternative, activated carbon can be used as a catalyst for sulfide oxidation of raw water. The use of different types of activated carbon was investigated in kinetic experiments. Both Catalytic Carbon from Calgon Carbon and granulated activated carbon from Norit showed high catalytic activities. The results of the experiments are discussed with regard to the practical use of activated carbon for the elimination of hydrogen sulfide during drinking water treatment. (orig.)

Novel Metal Sulfides to Achieve Effective Capture and Durable Consolidation of Radionuclides

International Nuclear Information System (INIS)

Kanatzidis, Mercouri; Riley, Brian; Chun, Jaehun; Pierce, D. A.

2016-01-01

This report documents the work done under NEUP grant to examine the capability of novel chalcogels and some binary metal chalcogenides as a host matrix for the capture of gaseous iodine and the feasibility of their iodine-laden materials to be converted into a permanent waste form. The presented work was conducted over last two years. A number of novel chalcogels Zn 2 Sn 2 S 6 , Sb 4 Sn 4 S 12 , NiMoS 4 , CoMoS 4 , antimony sulfide (SbS x ) chalcogels, silver functionalized chalcogels and binary metal sulfides (Sb 2 S 3 ) were developed and studied for their iodine absorption efficacies. A new and simple route was devised for the large scale preparation of antimony sulfide chalcogel. The chalcogel was obtained by treating Sb 2 S 3 with Na 2 S in the presence of water followed by addition of formamide. The obtained gels have a low-density sponge-like network of meso-porous nature having BET surface area of 125 m 2 /g. The chalcogels, silver functionalized chalcogel and the binary metal sulfides were exposed to iodine vapors in a closed container. Silver-functionalized chalcogels and Sb 2 S 3 powders showed iodine uptake up to 100 wt%, the highest iodine uptake of 200 wt% was observed for the SbS-III chalcogel. The PXRD patterns of iodine-laden specimens revealed that iodine shows spontaneous chemisorption to the matrix used. The iodine loaded chalcogels and the binary chalcogenides were sealed under vacuum in fused silica ampoules and heated in a temperature controlled furnace. The consolidated products were analyzed by PXRD, energy dispersive spectroscopy (EDS), UV-Vis and Raman spectroscopy. The final products were found to be amorphous in most of the cases with high amount (∼4-35 wt%) of iodine and approximately ∼60- 90 % of the absorbed iodine could be consolidated into the final waste form. Alginate reinforced composite scaffolds with SbS/SnS chalcogels and Sb 2 S 3 bulk powder were also fabricated aiming to study their efficacy as host matrices in

A Reaction Involving Oxygen and Metal Sulfides.

Science.gov (United States)

Hill, William D. Jr.

1986-01-01

Describes a procedure for oxygen generation by thermal decomposition of potassium chlorate in presence of manganese dioxide, reacted with various sulfides. Provides a table of sample product yields for various sulfides. (JM)

Characterization of Vadose Zone Sediment: Uncontaminated RCRA Borehole Core Samples and Composite Samples

International Nuclear Information System (INIS)

Serne, R. Jeffrey; Bjornstad, Bruce N.; Schaef, Herbert T.; Williams, Bruce A.; Lanigan, David C.; Horton, Duane G.; Clayton, Ray E.; Mitroshkov, Alexandre V.; Legore, Virginia L.; O'Hara, Matthew J.; Brown, Christopher F.; Parker, Kent E.; Kutnyakov, Igor V.; Serne, Jennifer N.; Last, George V.; Smith, Steven C.; Lindenmeier, Clark W.; Zachara, John M.; Burke, Deborah S.

2008-01-01

This report was revised in September 2008 to remove acid-extractable sodium data from Tables 4.14, 4.16, 5.20, 5.22, 5.43, and 5.45. The sodium data was removed due to potential contamination introduced during the acid extraction process. The rest of the text remains unchanged from the original report issued in February 2002. The overall goal of the of the Tank Farm Vadose Zone Project, led by CH2M HILL Hanford Group, Inc., is to define risks from past and future single-shell tank farm activities. To meet this goal, CH2M HILL Hanford Group, Inc. asked scientists from Pacific Northwest National Laboratory to perform detailed analyses on vadose zone sediment from within the S-SX Waste Management Area. This report is one in a series of four reports to present the results of these analyses. Specifically, this report contains all the geologic, geochemical, and selected physical characterization data collected on vadose zone sediment recovered from Resource Conservation and Recovery Act (RCRA) borehole bore samples and composite samples

Characterization of Vadose Zone Sediment: Uncontaminated RCRA Borehole Core Samples and Composite Samples

Energy Technology Data Exchange (ETDEWEB)

Serne, R. Jeffrey; Bjornstad, Bruce N.; Schaef, Herbert T.; Williams, Bruce A.; Lanigan, David C.; Horton, Duane G.; Clayton, Ray E.; Mitroshkov, Alexandre V.; Legore, Virginia L.; O' Hara, Matthew J.; Brown, Christopher F.; Parker, Kent E.; Kutnyakov, Igor V.; Serne, Jennifer N.; Last, George V.; Smith, Steven C.; Lindenmeier, Clark W.; Zachara, John M.; Burke, Deborah S.

2008-09-11

This report was revised in September 2008 to remove acid-extractable sodium data from Tables 4.14, 4.16, 5.20, 5.22, 5.43, and 5.45. The sodium data was removed due to potential contamination introduced during the acid extraction process. The rest of the text remains unchanged from the original report issued in February 2002. The overall goal of the of the Tank Farm Vadose Zone Project, led by CH2M HILL Hanford Group, Inc., is to define risks from past and future single-shell tank farm activities. To meet this goal, CH2M HILL Hanford Group, Inc. asked scientists from Pacific Northwest National Laboratory to perform detailed analyses on vadose zone sediment from within the S-SX Waste Management Area. This report is one in a series of four reports to present the results of these analyses. Specifically, this report contains all the geologic, geochemical, and selected physical characterization data collected on vadose zone sediment recovered from Resource Conservation and Recovery Act (RCRA) borehole bore samples and composite samples.

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.

Simultaneous removal of sulfide, nitrate and acetate: Kinetic modeling

Energy Technology Data Exchange (ETDEWEB)

Wang Aijie, E-mail: waj0578@hit.edu.cn [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (SKLUWRE, HIT), Harbin 150090 (China); Liu Chunshuang; Ren Nanqi; Han Hongjun [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (SKLUWRE, HIT), Harbin 150090 (China); Lee Duujong [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (SKLUWRE, HIT), Harbin 150090 (China); Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

2010-06-15

Biological removal of sulfide, nitrate and chemical oxygen demand (COD) simultaneously from industrial wastewaters to elementary sulfur (S{sup 0}), N{sub 2}, and CO{sub 2}, or named the denitrifying sulfide (DSR) process, is a cost effective and environmentally friendly treatment process for high strength sulfide and nitrate laden organic wastewater. Kinetic model for the DSR process was established for the first time on the basis of Activated Sludge Model No. 1 (ASM1). The DSR experiments were conducted at influent sulfide concentrations of 200-800 mg/L, whose results calibrate the model parameters. The model correlates well with the DSR process dynamics. By introducing the switch function and the inhibition function, the competition between autotrophic and heterotrophic denitrifiers is quantitatively described and the degree of inhibition of sulfide on heterotrophic denitrifiers is realized. The model output indicates that the DSR reactor can work well at 0.5 < C/S < 3.0 with influent sulfide concentration of 400-1000 mg/L. At >1000 mg/L influent sulfide, however, the DSR system will break down.

Use of sulfide-containing liquors for removing mercury from flue gases

Science.gov (United States)

Nolan, Paul S.; Downs, William; Bailey, Ralph T.; Vecci, Stanley J.

2006-05-02

A method and apparatus for reducing and removing mercury in industrial gases, such as a flue gas, produced by the combustion of fossil fuels, such as coal, adds sulfide ions to the flue gas as it passes through a scrubber. Ideally, the source of these sulfide ions may include at least one of: sulfidic waste water, kraft caustic liquor, kraft carbonate liquor, potassium sulfide, sodium sulfide, and thioacetamide. The sulfide ion source is introduced into the scrubbing liquor as an aqueous sulfide species. The scrubber may be either a wet or dry scrubber for flue gas desulfurization systems.

Thermoelectric properties of non-stoichiometric lanthanum sulfides

International Nuclear Information System (INIS)

Shapiro, E.; Danielson, L.R.

1983-01-01

The lanthanum sulfides are promising candidate materials for high-efficiency thermoelectric applications at temperatures up to 1300 0 C. The nonstoichiometric lanthanum sulfides (LaS /SUB x/ , where 1.33 2 //rho/ can be chosen. The thermal conductivity remains approximately constant with stoichiometry, so a material with an optimum value of α 2 //rho/ should possess the optimum figure-of-merit. Data for the Seebeck coefficient and electrical resistivity of non-stoichiometric lanthanum sulfides is presented, together with structural properties of these materials

Groundwater composition fluctuation within technogenic zones (case study: flooded coal mines in Primorsky Krai, Russia)

Science.gov (United States)

Tarasenko, I. A.; Zinkov, A. V.; Vakh, E. A.; Vetoshkina, A. V.; Strelnikova, A. B.

2016-03-01

The paper considers groundwater composition fluctuation within technogenic zones based on evidence from the flooded coal mines of Primorye. The authors have determined the regularities of hydrogeochemical processes, specified the groundwater composition fluctuation within the technogenic complexes located in the liquidated mine areas, and identified the equilibrium phases between the studied waters and specific secondary minerals. It has been proved that water within natural-technogenic complexes in the liquidated mine areas are saturated with silicates, carbonates, sulfates, oxides, and hydroxides, which should be taken into account when designing technologies for groundwater treatment.

Comparison of Carbon XANES Spectra from an Iron Sulfide from Comet Wild 2 with an Iron Sulfide Interplanetary Dust Particle

Science.gov (United States)

Wirick, S.; Flynn, G. J.; Keller, L. P.; Sanford, S. A.; Zolensky, M. E.; Messenger, Nakamura K.; Jacobsen, C.

2008-01-01

Among one of the first particles removed from the aerogel collector from the Stardust sample return mission was an approx. 5 micron sized iron sulfide. The majority of the spectra from 5 different sections of this particle suggests the presence of aliphatic compounds. Due to the heat of capture in the aerogel we initially assumed these aliphatic compounds were not cometary but after comparing these results to a heated iron sulfide interplanetary dust particle (IDP) we believe our initial interpretation of these spectra was not correct. It has been suggested that ice coating on iron sulfides leads to aqueous alteration in IDP clusters which can then lead to the formation of complex organic compounds from unprocessed organics in the IDPs similar to unprocessed organics found in comets [1]. Iron sulfides have been demonstrated to not only transform halogenated aliphatic hydrocarbons but also enhance the bonding of rubber to steel [2,3]. Bromfield and Coville (1997) demonstrated using Xray photoelectron spectroscopy that "the surface enhancement of segregated sulfur to the surface of sulfided precipitated iron catalysts facilitates the formation of a low-dimensional structure of extraordinary properties" [4]. It may be that the iron sulfide acts in some way to protect aliphatic compounds from alteration due to heat.

Normal zone soliton in large composite superconductors

International Nuclear Information System (INIS)

Kupferman, R.; Mints, R.G.; Ben-Jacob, E.

1992-01-01

The study of normal zone of finite size (normal domains) in superconductors, has been continuously a subject of interest in the field of applied superconductivity. It was shown that in homogeneous superconductors normal domains are always unstable, so that if a normal domain nucleates, it will either expand or shrink. While testing the stability of large cryostable composite superconductors, a new phenomena was found, the existence of stable propagating normal solitons. The formation of these propagating domains was shown to be a result of the high Joule power generated in the superconductor during the relatively long process of current redistribution between the superconductor and the stabilizer. Theoretical studies were performed in investigate the propagation of normal domains in large composite super conductors in the cryostable regime. Huang and Eyssa performed numerical calculations simulating the diffusion of heat and current redistribution in the conductor, and showed the existence of stable propagating normal domains. They compared the velocity of normal domain propagation with the experimental data, obtaining a reasonable agreement. Dresner presented an analytical method to solve this problem if the time dependence of the Joule power is given. He performed explicit calculations of normal domain velocity assuming that the Joule power decays exponentially during the process of current redistribution. In this paper, the authors propose a system of two one-dimensional diffusion equations describing the dynamics of the temperature and the current density distributions along the conductor. Numerical simulations of the equations reconfirm the existence of propagating domains in the cryostable regime, while an analytical investigation supplies an explicit formula for the velocity of the normal domain

High-resolution photoelectron spectroscopy analysis of sulfidation of brass at the rubber/brass interface

International Nuclear Information System (INIS)

Ozawa, Kenichi; Kakubo, Takashi; Shimizu, Katsunori; Amino, Naoya; Mase, Kazuhiko; Komatsu, Takayuki

2013-01-01

Highlights: ► Chemical composition at the rubber/brass interface is investigated. ► The 2-min vulcanization reaction is enough to convert the interface composition. ► Five S-containing species are identified at the interface. ► Strong rubber–brass adhesion is related to the Cu 2 S/CuS ratio. ► Degradation of adhesion proceeds along with desulfidation of the interface. - Abstract: High resolution photoelectron spectroscopy is utilized to investigate the chemical composition at the rubber/brass interface to elucidate the origin of strong adhesion as well as the degradation between rubber and brass. Special attention has been given to copper sulfides formed at the interface during the vulcanization reaction at 170 °C. At least five sulfur-containing species are identified in the adhesive interlayer including crystalline CuS and amorphous Cu x S (x ≃ 2). These copper sulfide species are not uniformly distributed within the layer, but there exits the concentration gradation; the concentration of Cu x S is high in the region on the rubber side and is diminished in the deeper region, while vice versa for that of CuS. Degradation of the interface adhesive strength by prolonged vulcanization arises from the decrease in the Cu x S/CuS ratio accompanying desulfurization of the adhesive layer.

Simultaneous removal of sulfide, nitrate and acetate: Kinetic modeling

International Nuclear Information System (INIS)

Wang Aijie; Liu Chunshuang; Ren Nanqi; Han Hongjun; Lee Duujong

2010-01-01

Biological removal of sulfide, nitrate and chemical oxygen demand (COD) simultaneously from industrial wastewaters to elementary sulfur (S 0 ), N 2 , and CO 2 , or named the denitrifying sulfide (DSR) process, is a cost effective and environmentally friendly treatment process for high strength sulfide and nitrate laden organic wastewater. Kinetic model for the DSR process was established for the first time on the basis of Activated Sludge Model No. 1 (ASM1). The DSR experiments were conducted at influent sulfide concentrations of 200-800 mg/L, whose results calibrate the model parameters. The model correlates well with the DSR process dynamics. By introducing the switch function and the inhibition function, the competition between autotrophic and heterotrophic denitrifiers is quantitatively described and the degree of inhibition of sulfide on heterotrophic denitrifiers is realized. The model output indicates that the DSR reactor can work well at 0.5 1000 mg/L influent sulfide, however, the DSR system will break down.

Hydrogen sulfide oxidation without oxygen - oxidation products and pathways

International Nuclear Information System (INIS)

Fossing, H.

1992-01-01

Hydrogen sulfide oxidation was studied in anoxic marine sediments-both in undisturbed sediment cores and in sediment slurries. The turn over of hydrogen sulfide was followed using 35 S-radiolabeled hydrogen sulfide which was injected into the sediment. However, isotope exchange reactions between the reduced sulfur compounds, in particular between elemental sulfur and hydrogen sulfide, influenced on the specific radioactivity of these pools. It was, therefore, not possible to measure the turn over rates of the reduced sulfur pools by the radiotracer technique but merely to use the radioisotope to demonstrate some of the oxidation products. Thiosulfate was one important intermediate in the anoxic oxidation of hydrogen sulfide and was continuously turned over by reduction, oxidation and disproportionation. The author discusses the importance of isotope exchange and also presents the results from experiments in which both 35 S-radiolabeled elemental sulfur, radiolabeled hydrogen sulfide and radiolabeled thiosulfate were used to study the intermediates in the oxidative pathways of the sulfur cycle

Composition, diversity and distribution of microbenthos across the intertidal zones of Ryazhkov Island (the White Sea).

Science.gov (United States)

Azovsky, Andrey; Saburova, Maria; Tikhonenkov, Denis; Khazanova, Ksenya; Esaulov, Anton; Mazei, Yuri

2013-11-01

The composition and distribution of the main unicellular eukaryotic groups (diatom algae, ciliates, dinoflagellates (DF), other phototrophic (PF) and heterotrophic flagellates (HF)) were investigated in sandy sediments at five stations allocated across the tidal sheltered beach of the White Sea. Overall, 75 diatoms, 98 ciliates, 16 DF, 3 PF and 34 HF species were identified; some are new records for the White Sea. Common species for each group are illustrated. Diatoms and ciliates showed high alpha-diversity (species richness per sample), whereas flagellates were characterized by high beta-diversity (species turnover across the intertidal flat). Each group demonstrated its own spatial pattern that was best matched with its own subset of abiotic variables, reflecting group-specific responses to environmental gradients. Species richness increased from the upper intertidal zone seaward for ciliates but decreased for HF, whereas autotrophs showed a relatively uniform pattern with a slight peak at the mid-intertidal zone. Across the littoral zone, all groups showed distinct compositional changes; however, the position of the boundary between "upper" and "lower" intertidal communities varied among groups. Most of the species found at Ryazhkov Island are known from many other regions worldwide, indicating a wide geographic distribution of microbial eukaryotic species. Copyright © 2013 Elsevier GmbH. All rights reserved.

Sulfide perovskites for solar energy conversion applications: computational screening and synthesis of the selected compound LaYS3

DEFF Research Database (Denmark)

Kuhar, Korina; Crovetto, Andrea; Pandey, Mohnish

2017-01-01

of ternary sulfides followed by synthesis and confirmation of the properties of one of the most promising materials. The screening focusses on materials with ABS3 composition taking both perovskite and non-perovskite structures into consideration, and the material selection is based on descriptors...

Reduction of produced elementary sulfur in denitrifying sulfide removal process.

Science.gov (United States)

Zhou, Xu; Liu, Lihong; Chen, Chuan; Ren, Nanqi; Wang, Aijie; Lee, Duu-Jong

2011-05-01

Denitrifying sulfide removal (DSR) processes simultaneously convert sulfide, nitrate, and chemical oxygen demand from industrial wastewater into elemental sulfur, dinitrogen gas, and carbon dioxide, respectively. The failure of a DSR process is signaled by high concentrations of sulfide in reactor effluent. Conventionally, DSR reactor failure is blamed for overcompetition for heterotroph to autotroph communities. This study indicates that the elementary sulfur produced by oxidizing sulfide that is a recoverable resource from sulfide-laden wastewaters can be reduced back to sulfide by sulfur-reducing Methanobacterium sp. The Methanobacterium sp. was stimulated with excess organic carbon (acetate) when nitrite was completely consumed by heterotrophic denitrifiers. Adjusting hydraulic retention time of a DSR reactor when nitrite is completely consumed provides an additional control variable for maximizing DSR performance.

Enhanced sulfidation xanthate flotation of malachite using ammonium ions as activator.

Science.gov (United States)

Wu, Dandan; Ma, Wenhui; Mao, Yingbo; Deng, Jiushuai; Wen, Shuming

2017-05-18

In this study, ammonium ion was used to enhance the sulfidation flotation of malachite. The effect of ammonium ion on the sulfidation flotation of malachite was investigated using microflotation test, inductively coupled plasma (ICP) analysis, zeta potential measurements, and scanning electron microscope analysis (SEM). The results of microflotation test show that the addition of sodium sulfide and ammonium sulfate resulted in better sulfidation than the addition of sodium sulfide alone. The results of ICP analysis indicate that the dissolution of enhanced sulfurized malachite surface is significantly decreased. Zeta potential measurements indicate that a smaller isoelectric point value and a large number of copper-sulfide films formed on the malachite surface by enhancing sulfidation resulted in a large amount of sodium butyl xanthate absorbed onto the enhanced sulfurized malachite surface. EDS semi-quantitative analysis and XPS analysis show that malachite was easily sulfurized by sodium sulfide with ammonium ion. These results show that the addition of ammonium ion plays a significant role in the sulfidation of malachite and results in improved flotation performance.

Physiological behavior of hydrogen sulfide in rice plant. Part 5. Effect of hydrogen sulfide on respiration of rice roots

Energy Technology Data Exchange (ETDEWEB)

Okajima, H; Takagi, S

1955-01-01

The inhibitory effects of hydrogen sulfide on the respiration of rice plant roots were investigated using Warburg's manometory technique. Hydrogen sulfide inhibited not only aerobic respiration but anaerobic respiration process of roots. Inhibitory action of hydrogen sulfide and potassium cyanide on the respiration were apparently reversible, but the style of recovery reaction from inhibition was somewhat different in each case. Oxygen consumption of roots was increased by addition of ammonium salts, but the same effects were not recognized by the addition of any other salt examined (except nitrate salts). There was close relationship between respiration of roots and assimilation of nitrogen by roots. The increased oxygen uptake by addition of ammonium salt was also inhibited by hydrogen sulfide. The reactivation of this reaction occurred with the recovery of endogenous respiration of roots. 19 references, 8 figures, 3 tables.

Native gold and gold-rich sulfide deposits in a submarine basaltic caldera, Higashi-Aogashima hydrothermal field, Izu-Ogasawara frontal arc, Japan

Science.gov (United States)

Iizasa, Kokichi; Asada, Akira; Mizuno, Katsunori; Katase, Fuyuki; Lee, Sangkyun; Kojima, Mitsuhiro; Ogawa, Nobuhiro

2018-04-01

Sulfide deposits with extremely high Au concentrations (up to 275 ppm; avg. 102 ppm, n = 15), high Au/Ag ratios (0.24, n = 15), and low Cu/(Cu + Zn) ratios (0.03, n = 15) were discovered in 2015 in active hydrothermal fields at a water depth of 760 m in a basalt-dominated submarine caldera in the Izu-Ogasawara frontal arc, Japan. Native gold grains occur in massive sulfide fragments, concretions, and metalliferous sediments from a sulfide mound (40 m across and 20 m high) with up to 30-m-high black smoker chimneys. Tiny native gold grains up to 14 μm in diameter are mainly present in sulfide fallouts from chimney orifices and plumes. Larger native gold grains up to 150 μm long occur mostly as discrete particles and/or with amorphous silica and sulfides. The larger gold grains are interpreted to represent direct precipitation from Au-bearing hydrothermal fluids circulating in and/or beneath the unconsolidated sulfide mound deposits. Sulfur isotope compositions from a limited number of sulfide separates (n = 4) range from 4.3 to 5.8‰ δ34S, similar to the quaternary volcanic rocks of the arc. Barite separates have values of 22.2 and 23.1‰, close to modern seawater values, and indicate probable seawater sulfate origin. The Cu, Zn, and Pb concentrations in bulk samples of sulfide-rich rocks are similar to those of volcanogenic massive sulfides formed in continental crustal environments. The gold is interpreted to have formed by low-temperature hydrothermal activity, perhaps genetically different from systems with documented magmatic contributions or from seafloor hydrothermal systems in other island arc settings. Its presence suggests that basalt-dominated submarine calderas situated on relatively thick continental crust in an intraoceanic arc setting such as the Higashi-Aogashima knoll caldera may be perspective for gold mineralization.

Enhanced sulfidation xanthate flotation of malachite using ammonium ions as activator

OpenAIRE

Dandan Wu; Wenhui Ma; Yingbo Mao; Jiushuai Deng; Shuming Wen

2017-01-01

In this study, ammonium ion was used to enhance the sulfidation flotation of malachite. The effect of ammonium ion on the sulfidation flotation of malachite was investigated using microflotation test, inductively coupled plasma (ICP) analysis, zeta potential measurements, and scanning electron microscope analysis (SEM). The results of microflotation test show that the addition of sodium sulfide and ammonium sulfate resulted in better sulfidation than the addition of sodium sulfide alone. The ...

Formation of Copper Sulfide Precipitate in Solid Iron

Science.gov (United States)

Urata, Kentaro; Kobayashi, Yoshinao

The growth rate of copper sulfide precipitates has been measured in low carbon steel samples such as Fe-0.3mass%Cu-0.03mass%S-0.1mass%C and Fe-0.1mass%Cu-0.01mass%S- 0.1mass%C. Heat-treatment of the samples was conducted at 1273, 1423 and 1573 K for 100 s - 14.4 ks for precipitation of copper sulfides and then the samples were observed by a scanning electron microscope and a transmission electron microscope to measure the diameter of copper sulfides precipitated in the samples. The growth rate of copper sulfide has been found to be well described by the Ostwald growth model, as follows: R\

Interfacial Reduction-Oxidation Mechanisms Governing Fate and Transport of Contaminants in the Vadose Zone

Energy Technology Data Exchange (ETDEWEB)

Principal Investigator: Baolin Deng, University of Missouri, Columbia, MO; Co-Principal Investigator: Silvia Sabine Jurisson, University of Missouri, Columbia, MO; Co-Principal Investigator: Edward C. Thornton, Pacific Northwest National Laboratory Richland, WA; Co-Principal Investigator: Jeff Terry, Illinois Institute of Technology, Chicago, IL

2008-05-12

There are many soil contamination sites at the Department of Energy (DOE) installations that contain radionuclides and toxic metals such as uranium (U), technetium (Tc), and chromium (Cr). Since these contaminants are the main 'risk drivers' at the Hanford site (WA) and some of them also pose significant risk at other DOE facilities (e.g., Oak Ridge Reservation - TN; Rocky Flats - CO), development of technologies for cost effective site remediation is needed. Current assessment indicates that complete removal of these contaminants for ex-situ disposal is infeasible, thus in-situ stabilization through reduction to insoluble species is considered one of the most important approaches for site remediation. In Situ Gaseous Reduction (ISGR) is a technology developed by Pacific Northwest National Laboratory (PNNL) for vadose zone soil remediation. The ISGR approach uses hydrogen sulfide (H{sub 2}S) for reductive immobilization of contaminants that show substantially lower mobility in their reduced forms (e.g., Tc, U, and Cr). The technology can be applied in two ways: (i) to immobilize or stabilize pre-existing contaminants in the vadose zone soils by direct H{sub 2}S treatment, or (ii) to create a permeable reactive barrier (PRB) that prevents the migration of contaminants. Direct treatment involves reduction of the contaminants by H{sub 2}S to less mobile species. Formation of a PRB is accomplished through reduction of ferric iron species in the vadose zone soils by H{sub 2}S to iron sulfides (e.g., FeS), which provides a means for capturing the contaminants entering the treated zone. Potential future releases may occur during tank closure activities. Thus, the placement of a permeable reactive barrier by ISGR treatment can be part of the leak mitigation program. Deployment of these ISGR approaches, however, requires a better understanding of the immobilization kinetics and mechanisms, and a better assessment of the long-term effectiveness of treatment. The

Eelgrass fairy rings: sulfide as inhibiting agent

DEFF Research Database (Denmark)

Borum, Jens; Raun, Ane-Marie Løvendahl; Hasler-Sheetal, Harald

2014-01-01

specifically, for the apparent die- off of eelgrass shoots on the inner side of the rings. The fairy rings were up to 15 m in diameter consisting of 0.3- to 1-m-wide zones of sea grass shoots at densities of up to 1,200 shoots m−2 and rooted in an up to 10-cm-thick sediment layer. On the outer side, shoots...... expanded over the bare chalk plates. On the inner side, shoots were smaller, had lower absolute and specific leaf growth, shoot density was lower and the sediment eroded leaving the bare chalk with scattered boulders behind. Sediment organic matter and nutrients and tissue nutrient contents were...... substantial invasion of sulfide from the sediment. neither the clonal growth pattern of eelgrass, sediment burial of shoots, hydrodynamic forcing nor nutrient limitation could explain the ring-shaped pattern. We conclude that the most likely explanation must be found in invasion of eelgrass shoots by toxic...

Synthesis and characterization of MoS2/Ti composite coatings on Ti6Al4V prepared by laser cladding

Science.gov (United States)

Yang, Rongjuan; Liu, Zongde; Wang, Yongtian; Yang, Guang; Li, Hongchuan

2013-02-01

The MoS2/Ti composite coating with sub-micron grade structure has been prepared on Ti6Al4V by laser method under argon protection. The morphology, microstructure, microhardness and friction coefficient of the coating were examined. The results indicated that the molybdenum disulfide was decomposed during melting and resolidification. The phase organization of composite coating mainly consisted of ternary element sulfides, molybdenum sulfides and titanium sulfides. The friction coefficient of and the surface roughness the MoS2/Ti coating were lower than those of Ti6Al4V. The composite coating exhibits excellent adhesion to the substrates, less surface roughness, good wear resistance and harder surface.

Elevated corrosion rates and hydrogen sulfide in homes with ‘Chinese Drywall’

International Nuclear Information System (INIS)

Allen, Joseph G.; MacIntosh, David L.; Saltzman, Lori E.; Baker, Brian J.; Matheson, Joanna M.; Recht, Joel R.; Minegishi, Taeko; Fragala, Matt A.; Myatt, Theodore A.; Spengler, John D.; Stewart, James H.; McCarthy, John F.

2012-01-01

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. 3 , p 2 S: 476 vs. 2 S: 1472 vs. 389 Å/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: ► Environmental measurements in homes with and without “Chinese Drywall” ► Homes with “Chinese Drywall” had higher hydrogen sulfide concentrations ► Homes with “Chinese Drywall” had elevated corrosion rates ► Study provides empirical evidence of reported associations

Pb and Sr isotopic systematics of some basalts and sulfides from the East Pacific Rise at 210N (project RITA)

International Nuclear Information System (INIS)

Vidal, P.; Clauer, N.

1981-01-01

Tholeiitic basalts and sulfide deposits from the 'Cyana' and 'Alvin' diving programs (RITA project) on the East Pacific Rise were analyzed for Pb and Sr isotopes. The basalt data plot within the field defined previously by other East Pacific Rise basalts ( 206 Pb/ 204 Pb: 18.35-18.58; 207 Pb/ 204 Pb: 15.48-15.53; 208 Pb/ 204 Pb: 37.8-38.1; 87 Sr/ 86 Sr: 0.7022-0.7025). Pb, U and Sr contents (approx. equal to 0.5, approx. equal to 0.05 and approx. equal to 110 ppm, respectively) and μ values (approx. equal to 6) are typical of MORB, whereas Th/U ratios (approx. equal to 3.5) are significantly higher. The Pb isotopic ratios of the sulfide samples are very homogeneous ( 206 Pb/ 204 Pb approx. equal to 18.47, 207 Pb/ 204 Pb approx. equal to 15.49, 208 Pb/ 204 Pb approx. equal to 37.90), and plot in the middle of the basalt field. This indicates that the sulfide Pb was derived from the basaltic crust without any significant contribution from either seawater or hemipelagic sediments, and the solutions from which the sulfiedes were deposited had uniform Pb isotopic composition. The Pb contents of three sulfide samples is relatively high (170-1310 ppm). The Sr contents of five sulfide samples are widely scattered from 12 to 210 ppm, with 87 Sr/ 86 Sr ratios intermediate between basaltic and seawater values (0.70554 +- 0.00005 to 0.70795 +- 0.00011). Leaching experiments show that both basalt-derived Sr and seawater Sr were present in the solutions which deposited the sulfides. In some cases, Sr was also adsorbed from seawater onto the sulfides following their deposition. Basalt-derived Sr and seawater Sr are also present in associated non-sulfide phases. (orig.)

Weathering of the New Albany Shale, Kentucky, USA: I. Weathering zones defined by mineralogy and major-element composition

Science.gov (United States)

Tuttle, M.L.W.; Breit, G.N.

2009-01-01

Comprehensive understanding of chemical and mineralogical changes induced by weathering is valuable information when considering the supply of nutrients and toxic elements from rocks. Here minerals that release and fix major elements during progressive weathering of a bed of Devonian New Albany Shale in eastern Kentucky are documented. Samples were collected from unweathered core (parent shale) and across an outcrop excavated into a hillside 40 year prior to sampling. Quantitative X-ray diffraction mineralogical data record progressive shale alteration across the outcrop. Mineral compositional changes reflect subtle alteration processes such as incongruent dissolution and cation exchange. Altered primary minerals include K-feldspars, plagioclase, calcite, pyrite, and chlorite. Secondary minerals include jarosite, gypsum, goethite, amorphous Fe(III) oxides and Fe(II)-Al sulfate salt (efflorescence). The mineralogy in weathered shale defines four weathered intervals on the outcrop-Zones A-C and soil. Alteration of the weakly weathered shale (Zone A) is attributed to the 40-a exposure of the shale. In this zone, pyrite oxidization produces acid that dissolves calcite and attacks chlorite, forming gypsum, jarosite, and minor efflorescent salt. The pre-excavation, active weathering front (Zone B) is where complete pyrite oxidation and alteration of feldspar and organic matter result in increased permeability. Acidic weathering solutions seep through the permeable shale and evaporate on the surface forming abundant efflorescent salt, jarosite and minor goethite. Intensely weathered shale (Zone C) is depleted in feldspars, chlorite, gypsum, jarosite and efflorescent salts, but has retained much of its primary quartz, illite and illite-smectite. Goethite and amorphous FE(III) oxides increase due to hydrolysis of jarosite. Enhanced permeability in this zone is due to a 14% loss of the original mass in parent shale. Denudation rates suggest that characteristics of Zone C

Nanoporous gold-based microbial biosensor for direct determination of sulfide.

Science.gov (United States)

Liu, Zhuang; Ma, Hanyue; Sun, Huihui; Gao, Rui; Liu, Honglei; Wang, Xia; Xu, Ping; Xun, Luying

2017-12-15

Environmental pollution caused by sulfide compounds has become a major problem for public health. Hence, there is an urgent need to explore a sensitive, selective, and simple sulfide detection method for environmental monitoring and protection. Here, a novel microbial biosensor was developed using recombinant Escherichia coli BL21 (E. coli BL21) expressing sulfide:quinone oxidoreductase (SQR) for sulfide detection. As an important enzyme involved in the initial step of sulfide metabolism, SQR oxidizes sulfides to polysulfides and transfers electrons to the electron transport chain. Nanoporous gold (NPG) with its unique properties was selected for recombinant E. coli BL21 cells immobilization, and then glassy carbon electrode (GCE) was modified by the resulting E. coli/NPG biocomposites to construct an E. coli/NPG/GCE bioelectrode. Due to the catalytic oxidation properties of NPG for sulfide, the electrochemical reaction of the E. coli/NPG/GCE bioelectrode is attributed to the co-catalysis of SQR and NPG. For sulfide detection, the E. coli/NPG/GCE bioelectrode showed a good linear response ranging from 50μM to 5mM, with a high sensitivity of 18.35μAmM -1 cm -2 and a low detection limit of 2.55μM. The anti-interference ability of the E. coli/NPG/GCE bioelectrode is better than that of enzyme-based inhibitive biosensors. Further, the E. coli/NPG/GCE bioelectrode was successfully applied to the detection of sulfide in wastewater. These unique properties potentially make the E. coli/NPG/GCE bioelectrode an excellent choice for reliable sulfide detection. Copyright © 2017 Elsevier B.V. All rights reserved.

LIGNOCELLULOSE NANOCOMPOSITE CONTAINING COPPER SULFIDE

Directory of Open Access Journals (Sweden)

Sanchi Nenkova

2011-04-01

Full Text Available Copper sulfide-containing lignocellulose nanocomposites with improved electroconductivity were obtained. Two methods for preparing the copper sulfide lignocellulose nanocomposites were developed. An optimization of the parameters for obtaining of the nanocomposites with respect to obtaining improved electroconductivity, economy, and lower quantities and concentration of copper and sulfur ions in waste waters was conducted. The mechanisms and schemes of delaying and subsequent connection of copper sulfides in the lignocellulosic matrix were investigated. The modification with a system of 2 components: cupric sulfate pentahydrate (CuSO4. 5H2O and sodium thiosulfate pentahydrate (Na2S2O3.5H2O for wood fibers is preferred. Optimal parameters were established for the process: 40 % of the reduction system; hydromodule M=1:6; and ratio of cupric sulfate pentahydrate:sodium thiosulfate pentahydrate = 1:2. The coordinative connection of copper ions with oxygen atoms of cellulose OH groups and aromatic nucleus in lignin macromolecule was observed.

Problems of Chernobyl Exclusion Zone

International Nuclear Information System (INIS)

Kholosha, V.Yi.

2014-01-01

The collection comprises the results of researches and design activity in the ChNPP exclusion zone, aimed at the development of technologies, equipment and devices for radioactive waste management and ChNPP accident clean-up, at studying the composition and structure of the Exclusion zone soil activity solid bearers, form transformation of the fission products of fuel fallout radionuclide composition in the ChNPP near zone, the spatial distribution of radionuclides and other radioecological issues.. Much attention is paid to medical and biological aspects of the accident influence on the flora, fauna and people's health, labour conditions and incidence of the workers of the Exclusion zone

Zinc sulfide thin films deposited by RF reactive sputtering for photovoltaic applications

International Nuclear Information System (INIS)

Shao Lexi; Chang, K.-H.; Hwang, H.-L.

2003-01-01

Zinc sulfide (ZnS) thin films with nano-scale grains of about 50 nm were deposited on glass substrates at a substrate temperature of 200 deg. C via RF reactive sputtering by using zinc plate target and hydrogen sulfide gas. The structure, compositions, electrical and optical characteristics of the deposited films were investigated for the photovoltaic device applications. All films showed a near stoichiometric composition as indicated in their AES data. Distinct single crystalline phase with preferential orientation along the (0 0 0 1) plane of wurtzite or the (1 1 1) plane of zinc blende (ZB) was revealed in their X-ray diffraction (XRD) patterns, and the spacing of the planes are well matched to those of (1 1 2) plane of the chalcopyrite CuInS 2 (CIS). UV-Vis measurement showed that the films had more than 65% transmittance in the wavelength larger than 350 nm, and the fundamental absorption edge shifted to shorter wavelength with the increase of sulfur incorporated in the films, which corresponds to an increase in the energy band gap ranging from 3.59 to 3.72 eV. It was found that ZnS films are suitable for use as the buffer layer of the CIS solar cells, and it is the viable alternative for replacing CdS in the photovoltaic cell structure

Antimony sulfide thin films prepared by laser assisted chemical bath deposition

International Nuclear Information System (INIS)

Shaji, S.; Garcia, L.V.; Loredo, S.L.; Krishnan, B.

2017-01-01

Highlights: • Antimony sulfide thin films were prepared by normal CBD and laser assisted CBD. • Characterized these films using XRD, XPS, AFM, optical and electrical measurements. • Accelerated growth was observed in the laser assisted CBD process. • These films were photoconductive. - Abstract: Antimony sulfide (Sb_2S_3) thin films were prepared by laser assisted chemical bath deposition (LACBD) technique. These thin films were deposited on glass substrates from a chemical bath containing antimony chloride, acetone and sodium thiosulfate under various conditions of normal chemical bath deposition (CBD) as well as in-situ irradiation of the chemical bath using a continuous laser of 532 nm wavelength. Structure, composition, morphology, optical and electrical properties of the Sb_2S_3 thin films produced by normal CBD and LACBD were analyzed by X-Ray diffraction (XRD), Raman Spectroscopy, Atomic force microscopy (AFM), X-Ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and Photoconductivity. The results showed that LACBD is an effective synthesis technique to obtain Sb_2S_3 thin films for optoelectronic applications.

Antimony sulfide thin films prepared by laser assisted chemical bath deposition

Energy Technology Data Exchange (ETDEWEB)

Shaji, S., E-mail: sshajis@yahoo.com [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); CIIDIT—Universidad Autónoma de Nuevo León, Apodaca, Nuevo León (Mexico); Garcia, L.V. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); Loredo, S.L. [Centro de Investigación en Materiales Avanzados (CIMAV), Unidad Monterrey, PIIT, Apodaca, Nuevo León (Mexico); Krishnan, B. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); CIIDIT—Universidad Autónoma de Nuevo León, Apodaca, Nuevo León (Mexico); and others

2017-01-30

Highlights: • Antimony sulfide thin films were prepared by normal CBD and laser assisted CBD. • Characterized these films using XRD, XPS, AFM, optical and electrical measurements. • Accelerated growth was observed in the laser assisted CBD process. • These films were photoconductive. - Abstract: Antimony sulfide (Sb{sub 2}S{sub 3}) thin films were prepared by laser assisted chemical bath deposition (LACBD) technique. These thin films were deposited on glass substrates from a chemical bath containing antimony chloride, acetone and sodium thiosulfate under various conditions of normal chemical bath deposition (CBD) as well as in-situ irradiation of the chemical bath using a continuous laser of 532 nm wavelength. Structure, composition, morphology, optical and electrical properties of the Sb{sub 2}S{sub 3} thin films produced by normal CBD and LACBD were analyzed by X-Ray diffraction (XRD), Raman Spectroscopy, Atomic force microscopy (AFM), X-Ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and Photoconductivity. The results showed that LACBD is an effective synthesis technique to obtain Sb{sub 2}S{sub 3} thin films for optoelectronic applications.

Cuprous sulfide as a film insulation for superconductors

International Nuclear Information System (INIS)

Wagner, G.R.; Uphoff, J.H.; Vecchio, P.D.

1982-01-01

The LCP test coil utilizes a conductor of forced-flow design having 486 strands of multifilametary Nb 3 Sn compacted in a stainless steel sheath. The impetus for the work reported here stemmed from the need for some form of insulation for those strands to prevent sintering during reaction and to reduce ac losses. The work reported here experimented with cuprous sulfide coatings at various coating rates and thicknesses. Two solenoids that were wound with cuprous sulfide-coated wires and heat-treated at 700 degrees C were found to demonstrate that the film is effective in providing turn-to-turn insulation for less than about 0.5V between turns. The sulfide layer provided a metal-semiconductor junction which became conducting at roughly 0.5V. Repeated cycling of the coil voltage in excess of that value produced no damage to the sulfide layer. The junction provided self-protection for the coil as long as the upper allowable current density in the sulfide was not exceeded. No training was apparent up to 6.4 T

Composition and Redox Potential of High-Grade Fluids: An Example from the Nilgiri Block, Southern India

Science.gov (United States)

Samuel, V. O.; Harlov, D. E.; Kwon, S.

2017-12-01

Composition and redox potential of fluids present during high-grade metamorphism exert an enormous influence on mineral textures and their regional trends within metamorphic complexes. We examine silicate, oxide, and sulfide trends in the Nilgiri Block, southern India. This terrain formed through subduction-related arc magmatic processes in the Neoarchean (ca. 2500 Ma). The Nilgiri highlands are characterized by granulite-facies metagabbro in the north, a two-pyroxene granulite transition zone, and tonalitic-granodioritic charnockites in the central and southern part. Garnet-orthopyroxene and orthopyroxene-clinopyroxene thermometry and garnet-orthopyroxene-plagioclase-quartz barometric results indicate a regional trend both in temperature ( 650 to 800 °C) and in pressure (700 to 1100 MPa) from SW to NE across the Nilgiri highlands. Regional trends are also seen in the oxide-sulfide mineralogy. The main oxide assemblage in the charnockites is rutile-ilmenite, whereas in the two-pyroxene granulites and metagabbros, hemo-ilmenite-magnetite dominates. The key sulfide mineral in the charnockites is pyrrhotite, with minor chalcopyrite. In the two-pyroxene granulites and metagabbros, the principle sulfide assemblage is pyrite +/- minor pyrrhotite. This reveals a regional oxidation trend. The metagabbros and two-pyroxene granulites are highly oxidized compared to the charnockites. Their higher oxidation state is proposed to be the result of highly oxidizing agents (probably as SO2) in low H2O activity fluids (most likely concentrated NaCl brines) during granulite-facies metamorphism of the metagabbros and two-pyroxene granulites. These agents were considerably more reducing (possibly as H2S) during granulite-facies metamorphism of the charnockites. This study emphasizes the potential role of oxidizing and reducing, low H2O activity fluids during granulite-facies metamorphism.

Remediation of Sulfidic Wastewater by Aeration in the Presence of Ultrasonic Vibration

Directory of Open Access Journals (Sweden)

F. Ahmad

2018-06-01

Full Text Available In the current study, the aerial oxidation of sodium sulfide in the presence of ultrasonic vibration is investigated. Sulfide analysis was carried out by the methylene blue method. Sodium sulfide is oxidized to elemental sulfur in the presence of ultrasonic vibration. The influence of air flow rate, initial sodium sulfide concentration and ultrasonic vibration intensity on the oxidation of sodium sulfide was investigated. The rate law equation regarding the oxidation of sulfide was determined from the experimental data. The order of reaction with respect to sulfide and oxygen was found to be 0.36 and 0.67 respectively. The overall reaction followed nearly first order kinetics.

Girdler-sulfide process physical properties

International Nuclear Information System (INIS)

Neuburg, H.J.; Atherley, J.F.; Walker, L.G.

1977-05-01

Physical properties of pure hydrogen sulfide and of gaseous and liquid solutions of the H 2 S-H 2 O system have been formulated. Tables for forty-nine different properties in the pressure and temperature range of interest to the Girdler-Sulfide (GS) process for heavy water production are given. All properties are presented in SI units. A computer program capable of calculating properties of the pure components as well as gaseous mixtures and liquid solutions at saturated and non-saturated conditions is included. (author)

Characterization of Vadose Zone Sediment: Uncontaminated RCRA Borehole Core Samples and Composite Samples

International Nuclear Information System (INIS)

Serne, R. Jeffrey; Bjornstad, Bruce N.; Schaef, Herbert T.; Williams, Bruce A.; Lanigan, David C.; Horton, Duane G.; Clayton, Ray E.; Mitroshkov, Alexandre V.; Legore, Virginia L.; O'Hara, Matthew J.; Brown, Christopher F.; Parker, Kent E.; Kutnyakov, Igor V.; Serne, Jennifer N.; Last, George V.; Smith, Steven C.; Lindenmeier, Clark W.; Zachara, John M.; Burke, Deborah Sd.

2001-01-01

The overall goal of the of the Tank Farm Vadose Zone Project, led by CH2M HILL Hanford Group, Inc., is to define risks from past and future single-shell tank farm activities. To meet this goal, CH2M HILL Hanford Group, Inc. asked scientists from Pacific Northwest National Laboratory to perform detailed analyses on vadose zone sediment from within the S-SX Waste Management Area. This report is the first in a series of four reports to present the results of these analyses. Specifically, this report contains all the geologic, geochemical, and selected physical characterization data collected on vadose zone sediment recovered from RCRA borehole bore samples and composite samples. Intact cores from two RCRA boreholes (299-W22-48 and 299-W22-50) near the SX Tank Farm and four, large-quantity grab samples from outcrop sediment on and off the Hanford Site were sampled to better understand the fate of contaminants in the vadose zone beneath underground storage tanks at the Hanford Site. Borehole and outcrop samples analyzed for this report are located outside the tank farms, and therefore may be considered standard or background samples from which to compare contaminated sediments within the tank farms themselves. This report presents our interpretation of the physical, chemical, and mineralogical properties of the uncontaminated vadose zone sediments, and variations in the vertical distribution of these properties. The information presented in this report is intended to support preparation of the S-SX Field Investigation Report to be prepared by CH2M Hill Hanford Group, Inc. as well as future remediation actions at the S-SX Tank Farm

Hydrogen sulfide production from cysteine and homocysteine by periodontal and oral bacteria.

Science.gov (United States)

Yoshida, Akihiro; Yoshimura, Mamiko; Ohara, Naoya; Yoshimura, Shigeru; Nagashima, Shiori; Takehara, Tadamichi; Nakayama, Koji

2009-11-01

Hydrogen sulfide is one of the predominant volatile sulfur compounds (VSCs) produced by oral bacteria. This study developed and evaluated a system for detecting hydrogen sulfide production by oral bacteria. L-methionine-alpha-deamino-gamma-mercaptomethane-lyase (METase) and beta carbon-sulfur (beta C-S) lyase were used to degrade homocysteine and cysteine, respectively, to produce hydrogen sulfide. Enzymatic reactions resulting in hydrogen sulfide production were assayed by reaction with bismuth trichloride, which forms a black precipitate when mixed with hydrogen sulfide. The enzymatic activities of various oral bacteria that result in hydrogen sulfide production and the capacity of bacteria from periodontal sites to form hydrogen sulfide in reaction mixtures containing L-cysteine or DL-homocysteine were assayed. With L-cysteine as the substrate, Streptococcus anginosus FW73 produced the most hydrogen sulfide, whereas Porphyromonas gingivalis American Type Culture Collection (ATCC) 33277 and W83 and Fusobacterium nucleatum ATCC 10953 produced approximately 35% of the amount produced by the P. gingivalis strains. Finally, the hydrogen sulfide found in subgingival plaque was analyzed. Using bismuth trichloride, the hydrogen sulfide produced by oral bacteria was visually detectable as a black precipitate. Hydrogen sulfide production by oral bacteria was easily analyzed using bismuth trichloride. However, further innovation is required for practical use.

Characteristics of a Low-Sulfidation Epithermal Deposit in the River Reef Zone and the Watuputih Hill, the Poboya Gold Prospect, Central Sulawesi, Indonesia: Host Rocks and Hydrothermal Alteration

Directory of Open Access Journals (Sweden)

Syafrizal

2017-07-01

Full Text Available Systematic exploration has delineated significant gold mineralization in the River Reef Zone and the presence of a siliceous body at Watuputih Hill, which is a Poboya gold prospect in Central Sulawesi, Indonesia. The mineralization is hosted within the Palu Metamorphic Complex. The host rocks consist of granite, biotite gneiss, and biotite schist, which is intercalated by feldspar porphyroblastic biotite schist and amphibolitic schist. The X-ray fluorescence (XRF analysis of the granite and biotite gneiss suggests that the granitic rocks can be characterized as magnesian arc calc-alkaline rocks, with a weakly peraluminous composition. Alteration minerals were analyzed by a combination of petrographic and X-ray diffraction (XRD. In the River Reef Zone, the hydrothermal alteration zones can be sorted by their proximity to the primary fluid conduit and divided into inner, high-T, and low-T propylitic zones. In Watuputih Hill, the hydrothermal alteration can be divided into advanced argillic and argillic zones. The hydrothermal alteration assemblages indicated that the fluid was at a near-neutral pH in the River Reef Zone, whereas the fluid was acidic within Watuputih Hill. Because the hill is relatively distant from the River Reef Zone, the presence of these zones at Watuputih Hill may be indicative of another mineralization system beneath the hill.

Analysis of Ecological Distribution and Genomic Content from a Clade of Bacteroidetes Endemic to Sulfidic Environments

Science.gov (United States)

Zhou, K.; Sylvan, J. B.; Hallam, S. J.

2017-12-01

The Bacteroidetes are a ubiquitous phylum of bacteria found in a wide variety of habitats. Marine Bacteroidetes are known to utilize complex carbohydrates and have a potentially important role in the global carbon cycle through processing these compounds, which are not digestible by many other microbes. Some members of the phylum are known to perform denitrification and are facultative anaerobes, but Bacteroidetes are not known to participate in sulfur redox cycling. Recently, it was shown that a clade of uncultured Bacteroidetes, including the VC2.1_Bac22 group, appears to be endemic to sulfidic environments, including hydrothermal vent sulfide chimneys, sediments and marine water column oxygen minimum zones (OMZs). This clade, dubbed the Sulfiphilic Bacteroidetes, is not detected in 16S rRNA amplicon studies from non-sulfidic environments. To test the hypothesis that the Sulphiphilic Bacteroidetes are involved in sulfur redox chemistry, we updated our meta-analysis of the clade using 16s rRNA sequences from public databases and employed single-cell genomics to survey their genomic potential using 19 single amplified genomes (SAGs) isolated from the seasonally anoxic Saanich Inlet, a seasonally hypoxic basin in British Columbia. Initial analysis of these SAGs indicates the Sulphiphilic Bacteroidetes may perform sulfur redox reactions using a three gene psrABC operon encoding the polysulfide reductase enzyme complex with a thiosulfate sulfurtransferase (rhodanese), which putatively uses cyanide to convert thiosulfate to sulfite, just upstream. Interestingly, this is the same configuration as discovered recently in some Marine Group A bacteria. Further aspects of the Sulphiphilic Bacteroidetes' genomic potential will be presented in light of their presence in sulfidic environments.

High-resolution photoelectron spectroscopy analysis of sulfidation of brass at the rubber/brass interface

Energy Technology Data Exchange (ETDEWEB)

Ozawa, Kenichi, E-mail: ozawa.k.ab@m.titech.ac.jp [Department of Chemistry and Materials Science, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8551 (Japan); Kakubo, Takashi; Shimizu, Katsunori; Amino, Naoya [Yokohama Rubber Co., Ltd., Oiwake, Hiratsuka 254-8601 (Japan); Mase, Kazuhiko [Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801 (Japan); Komatsu, Takayuki [Department of Chemistry and Materials Science, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8551 (Japan)

2013-01-01

Highlights: Black-Right-Pointing-Pointer Chemical composition at the rubber/brass interface is investigated. Black-Right-Pointing-Pointer The 2-min vulcanization reaction is enough to convert the interface composition. Black-Right-Pointing-Pointer Five S-containing species are identified at the interface. Black-Right-Pointing-Pointer Strong rubber-brass adhesion is related to the Cu{sub 2}S/CuS ratio. Black-Right-Pointing-Pointer Degradation of adhesion proceeds along with desulfidation of the interface. - Abstract: High resolution photoelectron spectroscopy is utilized to investigate the chemical composition at the rubber/brass interface to elucidate the origin of strong adhesion as well as the degradation between rubber and brass. Special attention has been given to copper sulfides formed at the interface during the vulcanization reaction at 170 Degree-Sign C. At least five sulfur-containing species are identified in the adhesive interlayer including crystalline CuS and amorphous Cu{sub x}S (x Asymptotically-Equal-To 2). These copper sulfide species are not uniformly distributed within the layer, but there exits the concentration gradation; the concentration of Cu{sub x}S is high in the region on the rubber side and is diminished in the deeper region, while vice versa for that of CuS. Degradation of the interface adhesive strength by prolonged vulcanization arises from the decrease in the Cu{sub x}S/CuS ratio accompanying desulfurization of the adhesive layer.

Stratigraphic setting and mineralogy of the Arctic volcanogenic massive sulfide prospect, Ambler district, Alaska.

Science.gov (United States)

Schmidt, J.M.

1986-01-01

The Arctic prospect, south central Brooks Range, is among the 30 largest of 508 volcanic-hosted massive sulphide deposits in the world. The massive sulphide lenses are interlayered with graphitic schist between metamorphosed rhyolite porphyries in Middle Devonian to early Mississippian metamorphosed volcanic, volcaniclastic and sedimentary rocks. Hydrothermal alteration is of three types: chloritic, phyllic s.l., and pyrite-phengite, each type strata-distinctively and respectively below, in, and above the sulphides. Maximum alteration conforms with metal zoning in the sulfides to suggest predominantly northwestward dispersal from a linear vent area in the elongate basin containing the deposit.-G.J.N.

Sulfidation of alumina-supported iron and iron-molybdenum oxide catalysts

NARCIS (Netherlands)

Ramselaar, W.L.T.M.; Crajé, M.W.J.; Hadders, R.H.; Gerkema, E.; Beer, de V.H.J.; Kraan, van der A.M.

1990-01-01

The transition of alumina-supported iron and iron-molybdenum catalysts from the oxidic precursor to the sulfided catalysts was systematically studied by means of in-situ Mössbauer spectroscopy at room temperature. This enabled the adjudgement of various sulfidic phases in the sulfided catalysts. The

Red coloration by heat treatment of the coprecipitate of cadmium sulfide and mercury(II) sulfide prepared from the nitrates

International Nuclear Information System (INIS)

Nakahara, Fujiya

1979-01-01

The effects of starting salts on the color, particle size and crystal structure of mercury-cadmium-sulfide pigments were investigated. The coprecipitate (N-S) of cadmium sulfide and mercury (II) sulfide was prepared by adding sodium sulfide solution to a mixed cadmium-mercury (II) nitrate solution. The coprecipitate (C-S) of cadmium sulfide and mercury (II) sulfide was also prepared from the mixed solution of their chlorides by the same method as described above. The coprecipitated products were heat-treated (calcination or hydrothermal treatment) at 350 0 C for 2 hours and subsequent changes in powder properties of both products were compared from each other. The powder properties of N-S, C-S and their heat-treated products were investigated by spectral reflectance, electron microscopy, X-ray diffraction and specific surface area measurements. Sample (N-C) obtained by the calcination of N-S was brown, indicating no red coloration, but the calcined product (C-C) of C-S developed a red color. Cl - and hot water were found to be effective for the red color development of the pigment. The effectiveness was confirmed by calcining N-S in the presence of NaCl or by treating it hydrothermally. It was found that halides other than NaCl, (e.g., NH 4 Cl, KCl, KBr and KI), were also effective for the color development of the pigment. The red samples are solid solutions with a basically hexagonal CdS structure, and it appears that CdS takes up HgS without any apparent structural changes. The particle size of the red samples are larger than those of the non red samples. (author)

Synthesis and characterization of MoS2/Ti composite coatings on Ti6Al4V prepared by laser cladding

Directory of Open Access Journals (Sweden)

Rongjuan Yang

2013-02-01

Full Text Available The MoS2/Ti composite coating with sub-micron grade structure has been prepared on Ti6Al4V by laser method under argon protection. The morphology, microstructure, microhardness and friction coefficient of the coating were examined. The results indicated that the molybdenum disulfide was decomposed during melting and resolidification. The phase organization of composite coating mainly consisted of ternary element sulfides, molybdenum sulfides and titanium sulfides. The friction coefficient of and the surface roughness the MoS2/Ti coating were lower than those of Ti6Al4V. The composite coating exhibits excellent adhesion to the substrates, less surface roughness, good wear resistance and harder surface.

A method for measuring sulfide toxicity in the nematode Caenorhabditis elegans.

Science.gov (United States)

Livshits, Leonid; Gross, Einav

2017-01-01

Cysteine catabolism by gut microbiota produces high levels of sulfide. Excessive sulfide can interfere with colon function, and therefore may be involved in the etiology and risk of relapse of ulcerative colitis, an inflammatory bowel disease affecting millions of people worldwide. Therefore, it is crucial to understand how cells/animals regulate the detoxification of sulfide generated by bacterial cysteine catabolism in the gut. Here we describe a simple and cost-effective way to explore the mechanism of sulfide toxicity in the nematode Caenorhabditis elegans ( C. elegans ). •A rapid cost-effective method to quantify and study sulfide tolerance in C. elegans and other free-living nematodes.•A cost effective method to measure the concentration of sulfide in the inverted plate assay.

A nonlinear model for fluid flow in a multiple-zone composite reservoir including the quadratic gradient term

International Nuclear Information System (INIS)

Wang, Xiao-Lu; Fan, Xiang-Yu; Nie, Ren-Shi; Huang, Quan-Hua; He, Yong-Ming

2013-01-01

Based on material balance and Darcy's law, the governing equation with the quadratic pressure gradient term was deduced. Then the nonlinear model for fluid flow in a multiple-zone composite reservoir including the quadratic gradient term was established and solved using a Laplace transform. A series of standard log–log type curves of 1-zone (homogeneous), 2-zone and 3-zone reservoirs were plotted and nonlinear flow characteristics were analysed. The type curves governed by the coefficient of the quadratic gradient term (β) gradually deviate from those of a linear model with time elapsing. Qualitative and quantitative analyses were implemented to compare the solutions of the linear and nonlinear models. The results showed that differences of pressure transients between the linear and nonlinear models increase with elapsed time and β. At the end, a successful application of the theoretical model data against the field data shows that the nonlinear model will be a good tool to evaluate formation parameters more accurately. (paper)

Hydrogen sulfide and nitric oxide metabolites in the blood of free-ranging brown bears and their potential roles in hibernation

DEFF Research Database (Denmark)

Revsbech, Inge G; Shen, Xinggui; Chakravarti, Ritu

2014-01-01

inhibitors of mitochondrial respiration, hydrogen sulfide (H2S) and nitric oxide (NO), in winter-hibernating and summer-active free-ranging Scandinavian brown bears. We found that levels of sulfide metabolites were overall similar in summer-active and hibernating bears but their composition in the plasma...... differed significantly, with a decrease in bound sulfane sulfur in hibernation. High levels of unbound free sulfide correlated with high levels of cysteine (Cys) and with low levels of bound sulfane sulfur, indicating that during hibernation H2S, in addition to being formed enzymatically from the substrate...... Cys, may also be regenerated from its oxidation products, including thiosulfate and polysulfides. In the absence of any dietary intake, this shift in the mode of H2S synthesis would help preserve free Cys for synthesis of glutathione (GSH), a major antioxidant found at high levels in the red blood...

The Archean komatiite-hosted, PGE-bearing Ni-Cu sulfide deposit at Vaara, eastern Finland: evidence for assimilation of external sulfur and post-depositional desulfurization

Science.gov (United States)

Konnunaho, J. P.; Hanski, E. J.; Bekker, A.; Halkoaho, T. A. A.; Hiebert, R. S.; Wing, B. A.

2013-12-01

Archean komatiites host important resources of Ni, Cu, Co, and PGE, particularly in Western Australia and Canada. In Finland, several small, low-grade sulfide deposits have been found in komatiites, including the ca. 2.8 Ga Vaara deposit in the Archean Suomussalmi greenstone belt. It occurs in the central part of the serpentinized olivine cumulate zone of a komatiitic extrusive body and is composed of disseminated interstitial sulfides consisting of pyrite, pentlandite, millerite, violarite, and chalcopyrite accompanied by abundant magnetite. Although currently subeconomic, the mineralization is interesting due to the very high chalcophile element contents of the sulfide fraction (38 wt% Ni, 3.4 wt% Cu, 0.7 wt% Co, 22.4 ppm Pd, and 9.5 ppm Pt). The sulfides occur in relatively Cr-poor olivine cumulates suggesting involvement of a chromite-undersaturated magma. The parental magma was an Al-undepleted komatiite with an estimated MgO content of at least 24 wt%. In contrast to the common komatiite types in the eastern Finland greenstone belts, the Vaara rocks are moderately enriched in LREE relative to MREE, suggesting that crustal contamination played an important role in the genesis of the Vaara deposit. Multiple sulfur isotope data reveal considerable mass-independent sulfur isotope fractionation both in country rock sedimentary sulfides (Δ33S ranges from -0.50 to +2.37 ‰) and in the Vaara mineralization (Δ33S ranges from +0.53 to +0.66 ‰), which provides strong evidence for incorporation of crustal sulfur. Extensive replacement of interstitial sulfides by magnetite and the presence of millerite- and violarite-bearing, pyrrhotite-free sulfide assemblages indicate significant post-magmatic, low-temperature hydrothermal oxidation of the primary magmatic pyrrhotite-pentlandite-chalcopyrite assemblages and associated sulfur loss that led to a significant upgrading of the original metal tenors of the Vaara deposit.

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.

Sulfidation of carbon-supported iron oxide catalysts

NARCIS (Netherlands)

Ramselaar, W.L.T.M.; Hadders, R.H.; Gerkema, E.; Beer, de V.H.J.; Oers, van E.M.; Kraan, van der A.M.

1989-01-01

The sulfidation of carbon-supported iron oxide catalysts was studied by means of in-situ Mössbauer spectroscopy at temperatures down to 4.2 K. The catalysts were dried in two different ways and then sulfided in a flow of 10% H2S in H2 at temperatures between 293 and 773 K. Thiophene

Optimization of the superconducting phase of hydrogen sulfide

Science.gov (United States)

Degtyarenko, N. N.; Masur, E. A.

2015-12-01

The electron and phonon spectra, as well as the densities of electron and phonon states of the SH3 phase and the stable orthorhombic structure of hydrogen sulfide SH2, are calculated for the pressure interval 100-225 GPa. It is found that the I4/ mmm phase can be responsible for the superconducting properties of metallic hydrogen sulfide along with the SH3 phase. Sequential stages for obtaining and conservation of the SH2 phase are proposed. The properties of two (SH2 and SH3) superconducting phases of hydrogen sulfide are compared.

Chemical dissolution of sulfide minerals

Science.gov (United States)

Chao, T.T.; Sanzolone, R.F.

1977-01-01

Chemical dissolution treatments involving the use of aqua regia, 4 N HNO3, H2O2-ascorbic acid, oxalic acid, KClO3+HCl, and KClO3+HCl followed by 4 N HNO3 were applied to specimens of nine common sulfide minerals (galena, chalcopyrite, cinnabar, molybdenite, orpiment, pyrite, stibnite, sphalerite, and tetrahedrite) mixed individually with a clay loam soil. The resultant decrease in the total sulfur content of the mixture, as determined by using the Leco induction furnace, was used to evaluate the effectiveness of each chemical treatment. A combination of KClO3+HCl followed by 4 N HNO3 boiling gently for 20 min has been shown to be very effective in dissolving all the sulfide minerals. This treatment is recommended to dissolve metals residing in sulfide minerals admixed with secondary weathering products, as one step in a fractionation scheme whereby metals in soluble and adsorbed forms, and those associated with organic materials and secondary oxides, are first removed by other chemical extractants.

Lanthanide complexes as luminogenic probes to measure sulfide levels in industrial samples

International Nuclear Information System (INIS)

Thorson, Megan K.; Ung, Phuc; Leaver, Franklin M.; Corbin, Teresa S.; Tuck, Kellie L.; Graham, Bim; Barrios, Amy M.

2015-01-01

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. - Highlights: • Lanthanide–azide based sulfide sensors were synthesized and characterized. • The probes have excitation and emission profiles compatible with sulfide-contaminated samples from the petrochemical industry. • A terbium-based probe was used to measure the sulfide concentration in oil refinery wastewater. • A europium-based probe had compatibility with partially refined crude oil samples.

Lanthanide complexes as luminogenic probes to measure sulfide levels in industrial samples

Energy Technology Data Exchange (ETDEWEB)

Thorson, Megan K. [Department of Medicinal Chemistry, University of Utah College of Pharmacy, Salt Lake City, UT 84108 (United States); Ung, Phuc [Monash Institute of Pharmaceutical Sciences, Monash University, Victoria 3052 (Australia); Leaver, Franklin M. [Water & Energy Systems Technology, Inc., Kaysville, UT 84037 (United States); Corbin, Teresa S. [Quality Services Laboratory, Tesoro Refining and Marketing, Salt Lake City, UT 84103 (United States); Tuck, Kellie L., E-mail: kellie.tuck@monash.edu [School of Chemistry, Monash University, Victoria 3800 (Australia); Graham, Bim, E-mail: bim.graham@monash.edu [Monash Institute of Pharmaceutical Sciences, Monash University, Victoria 3052 (Australia); Barrios, Amy M., E-mail: amy.barrios@utah.edu [Department of Medicinal Chemistry, University of Utah College of Pharmacy, Salt Lake City, UT 84108 (United States)

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. - Highlights: • Lanthanide–azide based sulfide sensors were synthesized and characterized. • The probes have excitation and emission profiles compatible with sulfide-contaminated samples from the petrochemical industry. • A terbium-based probe was used to measure the sulfide concentration in oil refinery wastewater. • A europium-based probe had compatibility with partially refined crude oil samples.

The solubility of iron sulfides and their role in mass transport in Girdler-Sulfide heavy water plants

International Nuclear Information System (INIS)

Tewari, P.H.; Wallace, G.; Campbell, A.B.

1978-04-01

The solubilities of several iron sulfides, mackinawite FeSsub((1-x)), troilite FeS, pyrrhotite Fesub((1-x))S (monoclinic and hexagonal), and pyrite FeS 2 have been determined in aqueous H 2 S solution at 0.1 MPa and 1.8 MPa H 2 S pressures between 25 deg and 125 deg C. The dependence of solubility on the pH of the medium has also been studied. It is concluded that since mackinawite is the most soluble of the iron sulfides, and has the highest dissolution rate and the steepest decline in solubility with temperature, its prolonged formation during plant operation should be avoided to minimize iron transport from lower to higher temperature areas in Girdler-Sulfide (G.S.) heavy water plants. This can be achieved by a preconditioning of carbon steel surfaces to convert mackinawite to pyrrhotite and pyrite

Laser cleaning of sulfide scale on compressor impeller blade

International Nuclear Information System (INIS)

Tang, Q.H.; Zhou, D.; Wang, Y.L.; Liu, G.F.

2015-01-01

Highlights: • The effects of sulfide layers and fluence values on the mechanism of laser cleaning were experimentally established. • The specimen surface with sulfide scale becomes slightly smoother than that before laser cleaning. • The mechanism of laser cleaning the sulfide scale of stainless steel is spallation without oxidization. • It would avoid chemical waste and dust pollution using a fiber laser instead of using nitric acids or sandblasting. - Abstract: Sulfide scale on the surface of a compressor impeller blade can considerably reduce the impeller performance and its service life. To prepare for subsequent remanufacturing, such as plasma spraying, it needs to be removed completely. In the corrosion process on an FV(520)B stainless steel, sulfide scale is divided into two layers because of different outward diffusion rates of Cr, Ni and Fe. In this paper, the cleaning threshold values of the upper and inner layers and the damage threshold value of the substrate were investigated using a pulsed fiber laser. To obtain experimental evidence, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and 3D surface profilometry were employed to investigate the two kinds of sulfide layers on specimens before, during, and after laser cleaning.

Effect of Sodium Sulfide on Ni-Containing Carbon Monoxide Dehydrogenases

Energy Technology Data Exchange (ETDEWEB)

Jian Feng; Paul A. Lindahl

2004-07-28

OAK-B135 The structure of the active-site C-cluster in CO dehydrogenase from Carboxythermus hydrogenoformans includes a {mu}{sup 2}-sulfide ion bridged to the Ni and unique Fe, while the same cluster in enzymes from Rhodospirillum rubrum (CODH{sub Rr}) and Moorella thermoacetica (CODH{sub Mt}) lack this ion. This difference was investigated by exploring the effects of sodium sulfide on activity and spectral properties. Sulfide partially inhibited the CO oxidation activity of CODH{sub Rr} and generated a lag prior to steady-state. CODH{sub Mt} was inhibited similarly but without a lag. Adding sulfide to CODH{sub Mt} in the C{sub red1} state caused the g{sub av} = 1.82 EPR signal to decline and new features to appear, including one with g = 1.95, 1.85 and (1.70 or 1.62). Removing sulfide caused the g{sub av} = 1.82 signal to reappear and activity to recover. Sulfide did not affect the g{sub av} = 1.86 signal from the C{sub red2} state. A model was developed in which sulfide binds reversibly to C{sub red1}, inhibiting catalysis. Reducing this adduct causes sulfide to dissociate, C{sub red2} to develop, and activity to recover. Using this model, apparent K{sub I} values are 40 {+-} 10 nM for CODH{sub Rr} and 60 {+-} 30 {micro}M for CODH{sub Mt}. Effects of sulfide are analogous to those of other anions, including the substrate hydroxyl group, suggesting that these ions also bridge the Ni and unique Fe. This proposed arrangement raises the possibility that CO binding labilizes the bridging hydroxyl and increases its nucleophilic tendency towards attacking Ni-bound carbonyl.

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,

Peculiarities of composition and morphology of the oxidation zone at Naimanzhal gold field

International Nuclear Information System (INIS)

Beryulin, V.V.

2000-01-01

Morphological and mineralogical characteristics of the Naimanzhal auriferous sulfur and complex ore deposit are described. These are: correspondence to oxidation zone (which is a combination of area and linear erosion crusts), size of explored part (up to 1,700 m long and 600-800 m wide and 5-60 m, sometimes even 80-120 m deep), mineralogical characteristics of ores (presence of arsenite pyrite with dependence of contents of copper), and favorable characteristics of chemical composition and mineralogy of gold, that allow extraction by means of heap leaching. (author)

ON THE DIVISION OF NORTH BOUNDARY OF SUBTROPICAL ZONE ACCORDING TO THE COMPOSITIONS AND PROPERTIES OF SOIL HUMUS

Institute of Scientific and Technical Information of China (English)

无

2002-01-01

In this paper predecessors′ achievements about the division between subtropical zone and warm temperate zone on the south slope of Funiu Mountain are firstly summarized, and the cause why these viewpoints about the division are different also has been presented. Seven soil profiles at different heights above sea level are dug along the south slope of Funiu Mountain. Many compositions and properties of soil humus have been analyzed in laboratory. A comprehensive study has been made about the division according to the compositions and properties of soil humus with mathematical method. During the analysis process eight indexes have been used, such as altitude, organic carbon, humic acid (HA), fulvic acid (FA), the ratio of humic acid and fulvic acid (HA/FA), two extinction coefficients (E4,E6), and their ratio (E4/E6).The result indicates that the boundary is at about 1000 meters above sea level.

ON THE DIVISION OF NORTH BOUNDARY OF SUBTROPICAL ZONE ACCORDING TO THE COMPOSITIONS AND PROPERTIES OF SOIL HUMUS

Institute of Scientific and Technical Information of China (English)

MAJian－hua; ZHAOQing－liang; 等

2002-01-01

In this paper predecessorsˊ achievements about the division between subtropical zone and warm temperate zone on the south slope of Funiu Mountain are firstly summarized,and the cause why these viewpoints about the division are different also has been presented.Seven soil profiles at different heights above sea level are dug along the south slope of Funiu Mountain.Many compositions and properties of soil humus have been analyzed in laboratory.A comprehensive study has been made about the division according to the compositions and properties of soil humus with mathematical method.During the analysis process eitht indexes have been used,such as altitude,organic carbon,humic acid(HA),fulvic acid(FA),the ratio of humic acid and fulvic acid(HA/FA),two extinction coefficients(E4,E6), and their ratio (E4/E6).The result indicates that the boundary is at about 1000 meters above sea level.

Source Of Hydrogen Sulfide To Sulfidic Spring And Watershed Ecosystems In Northern Sierra De Chiapas, Mexico Based On Sulfur And Carbon Isotopes

Science.gov (United States)

Rosales Lagarde, L.; Boston, P. J.; Campbell, A.

2013-12-01

At least four watersheds in northern Sierra de Chiapas, Mexico are fed by conspicuous karst sulfide-rich springs. The toxic hydrogen sulfide (H2S) in these springs nurtures rich ecosystems including especially adapted microorganisms, invertebrates and fish. Sulfur and carbon isotopic analysis of various chemical species in the spring water are integrated within their hydrogeologic context to evaluate the hydrogen sulfide source. Constraining the H2S origin can also increase the understanding of this compound effect in the quality of the nearby hydrocarbon reservoirs, and the extent to which its oxidation to sulfuric acid increases carbonate dissolution and steel corrosion in surface structures. The SO42-/H2S ratio in the spring water varies from 70,000 to 2 meq/L thus sulfate is the dominant species in the groundwater system. This sulfate is mainly produced from anhydrite dissolution based on its isotopic signature. The Δ SO42--H2S range of 16 spring water samples (30-50 ‰) is similar to the values determined by Goldhaber & Kaplan (1975) and Canfield (2001) for low rates of bacterial sulfate reduction suggesting that this is the most important mechanism producing H2S. Although the carbon isotopes do not constrain the nature of the organic matter participating in this reaction, this material likely comes from depth, perhaps as hydrocarbons, due to the apparent stability of the system. The organic matter availability and reactivity probably control the progress of sulfate reduction. The subsurface environments identified in the area also have different sulfur isotopic values. The heavier residual sulfate isotopic value in the Northern brackish springs (δ34S SO42- ≥ 18 ‰) compared to the Southern springs (δ34S SO42- ~18 ‰) suggests sulfate reduction is particularly enhanced in the former, probably by contribution of organic matter associated with oil produced water. In comparison, the composition of the Southern aquifer is mainly influenced by halite

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.

Process for scavenging hydrogen sulfide from hydrocarbon gases

International Nuclear Information System (INIS)

Fox, I.

1981-01-01

A process for scavenging hydrogen sulfide from hydrocarbon gases utilizes iron oxide particles of unique chemical and physical properties. These particles have large surface area, and are comprised substantially of amorphous Fe 2 O 3 containing a crystalline phase of Fe 2 O 3 , Fe 3 O 4 and combinations thereof. In scavenging hydrogen sulfide, the iron oxide particles are suspended in a liquid which enters into intimate mixing contact with hydrocarbon gases; the hydrogen sulfide is reacted at an exceptional rate and only acid-stable reaction products are formed. Thereafter, the sweetened hydrocarbon gases are collected

Denitrifying sulfide removal process on high-salinity wastewaters.

Science.gov (United States)

Liu, Chunshuang; Zhao, Chaocheng; Wang, Aijie; Guo, Yadong; Lee, Duu-Jong

2015-08-01

Denitrifying sulfide removal (DSR) process comprising both heterotrophic and autotrophic denitrifiers can simultaneously convert nitrate, sulfide, and acetate into nitrogen gas, elemental sulfur (S(0)), and carbon dioxide, respectively. Sulfide- and nitrate-laden wastewaters at 2-35 g/L NaCl were treated by DSR process. A C/N ratio of 3:1 was proposed to maintain high S(0) conversion rate. The granular sludge with a compact structure and smooth outer surface was formed. The microbial communities of DSR consortium via high-throughput sequencing method suggested that salinity shifts the predominating heterotrophic denitrifiers at 10 g/L NaCl.

Is succession in wet calcareous dune slacks affected by free sulfide?

NARCIS (Netherlands)

Adema, EB; van Gemerden, H; Grootjans, AP; Adema, Erwin B.; Grootjans, Ab P.; Rapson, G.

Consequences of sulfide toxicity on succession in wet calcareous dune slacks were investigated. Sulfide may exert an inhibitory effect on dune slack plants, but several pioneer species exhibit ROL (Radial Oxygen Loss) and thereby protect themselves against free sulfide. Under oxic conditions free

Titanocene sulfide chemistry

Czech Academy of Sciences Publication Activity Database

Horáček, Michal

2016-01-01

Roč. 314, MAY 2016 (2016), s. 83-102 ISSN 0010-8545 R&D Projects: GA ČR(CZ) GAP207/12/2368 Institutional support: RVO:61388955 Keywords : titanocene sulfide chemistry * photolysis * titanocene hydrosulfides Ti-(SH)n Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 13.324, year: 2016

Sulfur Cycling in an Iron Oxide-Dominated, Dynamic Marine Depositional System: The Argentine Continental Margin

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Natascha Riedinger

2017-05-01

Full Text Available The interplay between sediment deposition patterns, organic matter type and the quantity and quality of reactive mineral phases determines the accumulation, speciation, and isotope composition of pore water and solid phase sulfur constituents in marine sediments. Here, we present the sulfur geochemistry of siliciclastic sediments from two sites along the Argentine continental slope—a system characterized by dynamic deposition and reworking, which result in non-steady state conditions. The two investigated sites have different depositional histories but have in common that reactive iron phases are abundant and that organic matter is refractory—conditions that result in low organoclastic sulfate reduction rates (SRR. Deposition of reworked, isotopically light pyrite and sulfurized organic matter appear to be important contributors to the sulfur inventory, with only minor addition of pyrite from organoclastic sulfate reduction above the sulfate-methane transition (SMT. Pore-water sulfide is limited to a narrow zone at the SMT. The core of that zone is dominated by pyrite accumulation. Iron monosulfide and elemental sulfur accumulate above and below this zone. Iron monosulfide precipitation is driven by the reaction of low amounts of hydrogen sulfide with ferrous iron and is in competition with the oxidation of sulfide by iron (oxyhydroxides to form elemental sulfur. The intervals marked by precipitation of intermediate sulfur phases at the margin of the zone with free sulfide are bordered by two distinct peaks in total organic sulfur (TOS. Organic matter sulfurization appears to precede pyrite formation in the iron-dominated margins of the sulfide zone, potentially linked to the presence of polysulfides formed by reaction between dissolved sulfide and elemental sulfur. Thus, SMTs can be hotspots for organic matter sulfurization in sulfide-limited, reactive iron-rich marine sedimentary systems. Furthermore, existence of elemental sulfur and iron

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.

34S and 18O in dissolved sulfate as tracers of hydrogeochemical evolution of the Triassic carbonate aquifer exposed to intense groundwater exploitation (Olkusz-Zawiercie region, southern Poland)

International Nuclear Information System (INIS)

Samborska, Katarzyna; Halas, Stanislaw

2010-01-01

Research highlights: → Groundwater table rebound in aquifer containing sulfide ore. → Degradation of water quality causes by the significant increase in sulfate concentrations. → Isotopic examinations of sulfate and sulfate concentrations along flow path. → Sulfate concentrations as a result of binary mixing of sources (sulfide and evaporate). → Changes in isotopic composition of sulfide in extended vadose zone. - Abstract: The objective of this study was to determine the sources of SO 4 2- in groundwater of the Olkusz-Zawiercie Major Groundwater Body. The quality of groundwater was relatively good in the past, but fluctuations of the water table level have caused degradation of water quality. Variations in the water table level and the formation of the depression cone have resulted from both groundwater withdrawal and Zn-Pb mine dewatering. As a result within the extended vadose zone of the aquifer, weathering of pyrite and accompanying sulfides has taken place. Since 1992 the water table has risen and this process has been associated with an increase in concentrations of SO 4 2- , Ca and Mg. At the same time, the pH has decreased and periodically high Fe concentrations have been detected. High concentrations of Mg and Sr have been observed and, since gypsum layers are known to be present, a de-dolomitisation process has been hypothesized. The PHREEQC program for Windows was used to estimate saturation indices for calcite, dolomite, gypsum and epsomite. Isotopic data for SO 4 2- dissolved in the groundwater and archival data on isotopic composition of ore sulfides were used to solve the isotope balance equation and to estimate the fraction of dissolved SO 4 2- that originated from pyrite oxidation and gypsum dissolution. The results have shown that dissolution of pyrite oxidation products has a significant influence on chemical composition of groundwater, especially in the southern part of the cone of depression. By solving the additional, combined mass

Growth kinetics of hydrogen sulfide oxidizing bacteria in corroded concrete from sewers

International Nuclear Information System (INIS)

Jensen, Henriette Stokbro; Lens, Piet N.L.; Nielsen, Jeppe L.; Bester, Kai; Nielsen, Asbjorn Haaning; Hvitved-Jacobsen, Thorkild; Vollertsen, Jes

2011-01-01

Hydrogen sulfide oxidation by microbes present on concrete surfaces of sewer pipes is a key process in sewer corrosion. The growth of aerobic sulfur oxidizing bacteria from corroded concrete surfaces was studied in a batch reactor. Samples of corrosion products, containing sulfur oxidizing bacteria, were suspended in aqueous solution at pH similar to that of corroded concrete. Hydrogen sulfide was supplied to the reactor to provide the source of reduced sulfur. The removal of hydrogen sulfide and oxygen was monitored. The utilization rates of both hydrogen sulfide and oxygen suggested exponential bacterial growth with median growth rates of 1.25 d -1 and 1.33 d -1 as determined from the utilization rates of hydrogen sulfide and oxygen, respectively. Elemental sulfur was found to be the immediate product of the hydrogen sulfide oxidation. When exponential growth had been achieved, the addition of hydrogen sulfide was terminated leading to elemental sulfur oxidation. The ratio of consumed sulfur to consumed oxygen suggested that sulfuric acid was the ultimate oxidation product. To the knowledge of the authors, this is the first study to determine the growth rate of bacteria involved in concrete corrosion with hydrogen sulfide as source of reduced sulfur.

Isolation of Ochrobactrum sp.QZ2 from sulfide and nitrite treatment system

International Nuclear Information System (INIS)

Mahmood, Qaisar; Hu Baolan; Cai Jing; Zheng Ping; Azim, Muhammad Rashid; Jilani, Ghulam; Islam, Ejazul

2009-01-01

A bacterial strain QZ2 was isolated from sludge of anoxic sulfide-oxidizing (ASO) reactor. Based on 16S rDNA sequence analysis and morphology, the isolate was identified as Ochrobactrum sp. QZ2. The strain was facultative chemolithotroph, able of using sulfide to reduce nitrite anaerobically. It produced either elemental sulfur or sulfate as the product of sulfide oxidation, depending on the initial sulfide and nitrite concentrations. The optimum growth pH and temperature for Ochrobactrum sp. QZ2 were found as 6.5-7.0 and 30 deg. C, respectively. The specific growth rate (μ) was found as 0.06 h -1 with a doubling time of 19.75 h; the growth seemed more sensitive to highly alkaline pH. Ochrobactrum sp. QZ2 catalyzed sulfide oxidation to sulfate was more sensitive to sulfide compared with nitrite as indicated by IC 50 values for sulfide and nitrite utilization implying that isolate was relatively more tolerant to nitrite. The comparison of physiology of Ochrobactrum sp. QZ2 with those of other known sulfide-oxidizing bacteria suggested that the present isolate resembled to Ochrobactrum anthropi in its denitrification ability.

Novel Metal Sulfides to Achieve Effective Capture and Durable Consolidation of Radionuclides

Energy Technology Data Exchange (ETDEWEB)

Kanatzidis, Mercouri [Northwestern Univ., Evanston, IL (United States); Riley, Brian [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Chun, Jaehun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2016-01-30

This report documents the work done under NEUP grant to examine the capability of novel chalcogels and some binary metal chalcogenides as a host matrix for the capture of gaseous iodine and the feasibility of their iodine-laden materials to be converted into a permanent waste form. The presented work was conducted over last two years. A number of novel chalcogels Zn₂Sn₂S₆, Sb₄Sn₄S₁₂, NiMoS₄, CoMoS₄, antimony sulfide (SbS_x) chalcogels, silver functionalized chalcogels and binary metal sulfides (Sb₂S₃) were developed and studies for their iodine absorption efficacies. A new and simple route was devised for the large scale preparation of antimony sulfide chalcogel. The chalcogel was obtained by treating Sb₂S₃ with Na₂S in the presence of water followed by addition of formamide. The obtained gels have a low-density sponge like network of meso porous nature having BET surface area of 125 m²/g. The chalcogels, silver functionalized chalcogel and the binary metal sulfides were exposed to iodine vapors in a closed container. Silver-functionalized chalcogels and Sb₂S₃ powders showed iodine uptake up to 100 wt%, the highest iodine uptake of 200 wt% was observed for the SbS-III chalcogel. The PXRD patterns of iodine-laden specimens revealed that iodine shows spontaneous chemisorption to the matrix used. The iodine loaded chalcogels and the binary chalcogenides were sealed under vacuum in fused silica ampoules and heated in a temperature controlled furnace. The consolidated products were analyzed by PXRD, energy dispersive spectroscopy (EDS), UV-Vis and Raman spectroscopy. The final products were found to be amorphous in most of the cases with high amount (~4-35 wt%) of iodine and aapproximately ~60- 90 % of the absorbed iodine could be consolidated into the final waste form. Alginate

Komatiites and nickel sulfide ores of the Black Swan area, Yilgarn Craton, Western Australia. 2: Geology and genesis of the orebodies

Science.gov (United States)

Dowling, S. E.; Barnes, S. J.; Hill, R. E. T.; Hicks, J. D.

2004-11-01

The Black Swan Ultramafic Succession hosts a number of magmatic Fe Ni Cu PGE sulfide ore shoots, ranging from high grade massive ore to low grade disseminated sulfides. Of these, the most economically significant is the Silver Swan massive sulfide orebody, associated with the basal contact of the succession. The deposit varies in thickness between 5 and 20 m, reaches a N S strike length of 75 m, extends for at least 1.2 km of vertical plunge and is open at depth. Overlying matrix (net-textured) ore is rare. Inclusions of dacite are abundant within the lower 5 m of the massive sulfide. They range from angular fragments through smooth sinuous and plumose morphologies to fine lace-like intergrowths with the sulfide matrix, and comprise variable proportions of cores of porphyritic dacite and carapaces with skeletal plagioclase phenocrysts. Dynamic crystallisation and kinetic melting textures in the carapaces indicate that the inclusions have been heated to various temperatures, some well above their liquidus temperature. The composition of the inclusions ranges from a perfect match with the immediate footwall dacites to mixtures of dacite with up to 30% komatiite. The consistent thickness of the inclusion-bearing basal layer within the massive sulphide is interpreted as the extent of 3-D physical connectivity between the inclusions and a partially molten underlying hybrid layer. Primary contacts between the Silver Swan massive sulfide orebody and overlying ultramafic rocks are marked by thin rinds containing coarse-grained chevron-textured chromites with skeletal textures. Compositions of these chromites match those from Kambalda, Perseverance and other localities, and are inconsistent with a metamorphic origin. They are interpreted as markers of primary magmatic contacts. The combination of this feature with the general paucity of matrix ore implies that the massive ore accumulated and solidified before the accumulation of the overlying thick sequence of olivine

Evaluation of capillary zone electrophoresis for the determination of protein composition in therapeutic immunoglobulins and human albumins.

Science.gov (United States)

Christians, Stefan; van Treel, Nadine Denise; Bieniara, Gabriele; Eulig-Wien, Annika; Hanschmann, Kay-Martin; Giess, Siegfried

2016-07-01

Capillary zone electrophoresis (CZE) provides an alternative means of separating native proteins on the basis of their inherent electrophoretic mobilities. The major advantage of CZE is the quantification by UV detection, circumventing the drawbacks of staining and densitometry in the case of gel electrophoresis methods. The data of this validation study showed that CZE is a reliable assay for the determination of protein composition in therapeutic preparations of human albumin and human polyclonal immunoglobulins. Data obtained by CZE are in line with "historical" data obtained by the compendial method, provided that peak integration is performed without time correction. The focus here was to establish a rapid and reliable test to substitute the current gel based zone electrophoresis techniques for the control of protein composition of human immunoglobulins or albumins in the European Pharmacopoeia. We believe that the more advanced and modern CZE method described here is a very good alternative to the procedures currently described in the relevant monographs. Copyright © 2016 International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.

Fast Oxidation Processes in a Naturally Reduced Aquifer Zone Caused by Dissolved Oxygen

Science.gov (United States)

Davis, J. A.; Jemison, N. E.; Williams, K. H.; Hobson, C.; Bush, R. P.

2014-12-01

The occurrence of naturally reduced zones is quite common in alluvial aquifers in the western U.S.A. due to the burial of woody debris in flood plains. The naturally reduced zones are heterogeneously dispersed in such aquifers and are characterized by high concentrations of organic carbon and reduced phases, including iron sulfides and reduced forms of metals, including uranium(IV). The persistence of high concentrations of dissolved uranium(VI) at uranium-contaminated aquifers on the Colorado Plateau has been attributed to slow oxidation of insoluble uranium(IV) mineral phases that are found in association with these natural reducing zones, although there is little understanding of the relative importance of various potential oxidants. Three field experiments were conducted within an alluvial aquifer adjacent to the Colorado River near Rifle, CO wherein groundwater associated with naturally reduced zones was pumped into a gas-impermeable tank, mixed with a conservative tracer (Br-), bubbled with a gas phase composed of 97% O2 and 3% CO2, and then returned to the subsurface in the same well from which it was withdrawn. Within minutes of re-injection of the oxygenated groundwater, dissolved uranium(VI) concentrations increased from less than 1 μM to greater than 2.5 μM, demonstrating that oxygen can be an important oxidant for uranium in these field systems if supplied to the naturally reduced zones. Small concentrations of nitrate were also observed in the previously nitrate-free groundwater, and Fe(II) decreased to the detection limit. These results contrast with other laboratory and field results in which oxygen was introduced to systems containing high concentrations of mackinawite (FeS) rather than the more crystalline iron sulfides found in aged, naturally reduced zones. The flux of oxygen to the naturally reduced zones in the alluvial aquifers occurs mainly through interactions between groundwater and gas phases at the water table, and seasonal variations

Structural and optical properties of tin (II) sulfide thin films deposited using organophosphorus precursor (Ph3PS)

Science.gov (United States)

Assili, Kawther; Alouani, Khaled; Vilanova, Xavier

2017-02-01

Tin sulfide (SnS) thin films have been deposited onto glass substrates using triphenylphosphine sulfide (Ph3PS) as a sulfur precursor in a chemical vapor deposition reactor in a temperature range of 250 °C-400 °C. The influence of the sulphidisation temperature in the crystal structure, surface morphology, chemical composition and optical properties has been investigated. X-ray diffraction, energy dispersive analysis of x-rays, and Raman spectroscopy showed that pure SnS thin films have been successfully obtained at 250 °C. All the deposited films were polycrystalline and showed orthorhombic structure, with a preferential orientation according to the direction . The optical measurements showed that the films deposited exhibited a direct allowed transition and have a relatively high absorption coefficient. The presence of mixed tin sulfide phases granted by the variation of the sulphidisation temperature has affected the optical properties of the deposited films. The refractive index (n) and extinction coefficient (k), has low values compared to conventional semiconductor materials. The grown films can be considered as a good light absorbing material and a promising candidate for application in optoelectronic devices.

Source of boron in the Palokas gold deposit, northern Finland: evidence from boron isotopes and major element composition of tourmaline

Science.gov (United States)

Ranta, Jukka-Pekka; Hanski, Eero; Cook, Nick; Lahaye, Yann

2017-06-01

The recently discovered Palokas gold deposit is part of the larger Rompas-Rajapalot gold-mineralized system located in the Paleoproterozoic Peräpohja Belt, northern Finland. Tourmaline is an important gangue mineral in the Palokas gold mineralization. It occurs as tourmalinite veins and as tourmaline crystals in sulfide-rich metasomatized gold-bearing rocks. In order to understand the origin of tourmaline in the gold-mineralized rocks, we have investigated the major element chemistry and boron isotope composition of tourmaline from three areas: (1) the Palokas gold mineralization, (2) a pegmatitic tourmaline granite, and (3) the evaporitic Petäjäskoski Formation. Based on textural evidence, tourmaline in gold mineralization is divided into two different types. Type 1 is located within the host rock and is cut by rock-forming anthophyllite crystals. Type 2 occurs in late veins and/or breccia zones consisting of approximately 80% tourmaline and 20% sulfides, commonly adjacent to quartz veins. All the studied tourmaline samples belong to the alkali-group tourmaline and can be classified as dravite and schorl. The δ11B values of the three localities lie in the same range, from 0 to -4‰. Tourmaline from the Au mineralization and from the Petäjäskoski Formation has similar compositional trends. Mg is the major substituent for Al; inferred low Fe3+/Fe2+ ratios and Na values (molybdenite related to the tourmaline-sulfide-quartz veins, we propose that the tourmaline-forming process is a result of a single magmatic-hydrothermal event related to the extensive granite magmatism at around 1.79-1.77 Ga. Tourmaline was crystallized throughout the hydrothermal process, which resulted in the paragenetic variation between type 1 and type 2. The close association of tourmaline and gold suggests that the gold precipitated from the same boron-rich source as tourmaline.

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

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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.

Response of herbaceous plant community diversity and composition to overstorey harvest within riparian management zones in Northern Hardwoods

Science.gov (United States)

Eric K. Zenner; Michelle A. Martin; Brian J. Palik; Jerilynn E. Peck; Charles R. Blinn

2013-01-01

Partial timber harvest within riparian management zones (RMZs) may permit active management of riparian forests while protecting stream ecosystems, but impacts on herbaceous communities are poorly understood. We compared herbaceous plant community abundance, diversity and composition in RMZs along small streams in northern Minnesota, USA, among four treatments before...

Chemical composition of ground water and the locations of permeable zones in the Yucca Mountain area, Nevada

International Nuclear Information System (INIS)

Benson, L.V.; Robison, J.H.; Blankennagel, R.K.; Ogard, A.E.

1983-01-01

Ten wells in the Yucca Mountain area of southern Nevada have been sampled for chemical analysis. Samples were obtained during pumping of water from the entire well bore (composite sample) and in one instance by pumping water from a single isolated interval in well UE-25b number 1. Sodium is the most abundant cation and bicarbonate the most abundant anion in all water samples. Although the general chemical compositions of individual samples are similar, there are significant differences in uncorrected carbon-14 age and in inorganic and stable-isotope composition. Flow surveys of seven wells performed using iodine-131 as a tracer indicate that ground-water production is usually from one or more discrete zones of permeability. 7 references, 12 figures, 1 table

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

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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.

The effect of aerobic corrosion on anaerobically-formed sulfide layers on carbon steel in dilute near-neutral pH saline solutions

International Nuclear Information System (INIS)

Sherar, B.W.A.; Keech, P.G.; Shoesmith, D.W.

2013-01-01

Highlights: •The corrosion rate is low when steel is exposed to anaerobic conditions (pH = 8.9). •An anaerobic corrosion with sulfide to aerobic switch increases the corrosion rate. •Aerobic conditions leads to corrosion and oxide deposition beneath FeS. •Continual air exposure leads to the blistering of the original FeS film. -- Abstract: The aerobic corrosion of pipeline steel was investigated in an aqueous sulfide solution by monitoring the corrosion potential and periodically measuring the polarization resistance. The properties and composition of the corrosion product deposits formed were determined using scanning electron microscopy, energy dispersive X-ray analysis, and Raman spectroscopy. The establishment of aerobic conditions leads to corrosion and (oxyhydr)oxide deposition beneath the anaerobically-formed mackinawite film originally present on the steel surface. This leads to blistering and spalling of the sulfide film. Chemical conversion of the mackinawite to Fe(III) (oxyhydr)oxides also occurs but is a relatively slow reaction

INVESTIGATIONS ON BIOCHEMICAL PURIFICATION OF GROUND WATER FROM HYDROGEN SULFIDE

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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

Sulfur Concentration at Sulfide Saturation in Anhydrous Silicate Melts at Crustal Conditions

Science.gov (United States)

Liu, Y.; Samaha, N.; Baker, D. R.

2006-05-01

The sulfur concentration in silicate melts at sulfide saturation (SCSS) was experimentally investigated in a temperature range from 1250°C to 1450°C and a pressure range from 500 MPa to 1 GPa in a piston-cylinder apparatus. The investigated melt compositions varied from rhyolitic to basaltic. All experiments were saturated with a FeS melt. Temperature was confirmed to have a positive effect on the SCSS and no measurable pressure effect was observed. Oxygen fugacity was controlled to be either near the carbon-carbon monoxide buffer or one log unit above the nickel-nickel oxide buffer, and found to positively affect the SCSS. A series of models were constructed to predict the SCSS as a function of temperature, pressure, melt composition, oxygen fugacity and sulfur fugacity of the system. The coefficients were obtained by the regression of experimental data from this study and from data in the literature. The best model found for the prediction of the SCSS is: ln S (ppm) = 996/T + 9.875 + 0.997 ln MFM + 0.1901 ln fO2 - 0.0722 (P/T) -0.115 ln f S2, where P is in bar, T is in K, and MFM is a compositional parameter describing the melt based upon cation mole fractions: MFM = [Na + K + 2 (Ca + Mg+ Fe2+)]/[Si × (Al + Fe3+)]. This model predicts the SCSS in anhydrous silicate melts from rhyolitic to basaltic compositions at crustal conditions from 1 bar to 1.25 GPa, temperatures from ~1200 to 1400 C, and oxygen fugacities between approximately two log units below the fayalite-quartz-magnetite buffer and one log unit above the nickel-nickel oxide buffer. For cases where the oxygen and sulfur fugacities can not be adequately estimated a simpler model also works acceptably: ln S (ppm) = -5328/T + 8.431 + 1.244 ln MFM - 0.01704(P/T) + ln aFeS, where aFeS is the activity of FeS in the sulfide melt and is well approximated by a value of 1. Additional experiments were performed on other basalts in a temperature range from 1250 C to 1450 C at 1 GPa to test the models. The model

Cohesive Zone Model Based Numerical Analysis of Steel-Concrete Composite Structure Push-Out Tests

Directory of Open Access Journals (Sweden)

J. P. Lin

2014-01-01

Full Text Available Push-out tests were widely used to determine the shear bearing capacity and shear stiffness of shear connectors in steel-concrete composite structures. The finite element method was one efficient alternative to push-out testing. This paper focused on a simulation analysis of the interface between concrete slabs and steel girder flanges as well as the interface of the shear connectors and the surrounding concrete. A cohesive zone model was used to simulate the tangential sliding and normal separation of the interfaces. Then, a zero-thickness cohesive element was implemented via the user-defined element subroutine UEL in the software ABAQUS, and a multiple broken line mode was used to define the constitutive relations of the cohesive zone. A three-dimensional numerical analysis model was established for push-out testing to analyze the load-displacement curves of the push-out test process, interface relative displacement, and interface stress distribution. This method was found to accurately calculate the shear capacity and shear stiffness of shear connectors. The numerical results showed that the multiple broken lines mode cohesive zone model could describe the nonlinear mechanical behavior of the interface between steel and concrete and that a discontinuous deformation numerical simulation could be implemented.

Component, Disperse and Morphological Composition of Ambient Air Dust Contamination in the Zones of Mining-Processing Enterprises

Science.gov (United States)

Zagorodnov, S. Y.; Kokoulina, A. A.; Klein, S. V.

2017-07-01

The article presents the results of complex studies of dust emissions of the mining and processing complex. The main technological processes and the sources operation that produce intense dust emissions are determined. It has been proved that dust emissions of the investigated enterprise contain fine dust dangerous for human health. The results of the studies allowed us to detect precisely the dispersed composition of dust emissions, with the separation of PM10 and PM2.5 fractions, the chemical composition of the dust, and the shape of the particles. Thus, operating with obtained data on dispersed composition of the dust emissions and the specified sedimentation coefficient, we were able to calculate the dispersion of all solid particles and separately the PM10 and PM2.5 at the location of the enterprise. The dust exposure of the population at the targeted zones has been also determined. The obtained concentration values were used for assess health risk level to population living at the border of sanitary protection zone of the enterprise. Due to the obtained results, the enterprise was provided with recommendations on the inclusion of fine particles PM 10 and PM 2.5 in the production control program. In the case of increasing its production capacity was recommended to introduce the environmental measures for the reduction of emission of the finely dispersed fractions PM10 and PM 2.5.

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).

A sulfidation-resistant nickel-base alloy

International Nuclear Information System (INIS)

Lai, G.Y.

1989-01-01

For applications in mildly to moderately sulfidizing environments, stainless steels, Fe-Ni-Cr alloys (e.g., alloys 800 and 330), and more recently Fe-Ni-Cr-Co alloys (e.g., alloy 556) are frequently used for construction of process equipment. However, for many highly sulfidizing environments, few existing commercial alloys have adequate performance. Thus, a new nickel-based alloy containing 27 wt.% Co, 28 wt.% Cr, 4 wt.% Fe, 2.75 wt.% Si, 0.5 wt.% Mn and 0.05 wt.% C (Haynes alloy HR-160) was developed

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.

Surface modification of malachite with ethanediamine and its effect on sulfidization flotation

Science.gov (United States)

Feng, Qicheng; Zhao, Wenjuan; Wen, Shuming

2018-04-01

Ethanediamine was used to modify the mineral surface of malachite to improve its sulfidization and flotation behavior. The activation mechanism was investigated by adsorption experiments, X-ray photoelectron spectroscopy (XPS) analysis, and zeta potential measurements. Microflotation experiments showed that the flotation recovery of malachite was enhanced after the pretreatment of the mineral particles with ethanediamine prior to the addition of Na2S. Adsorption tests revealed that numerous sulfide ion species in the pulp solution were transferred onto the mineral surface through the formation of more copper sulfide species. This finding was confirmed by the results of the XPS measurements. Ethanediamine modification not only increased the contents of copper sulfide species on the malachite surface but also enhanced the reactivity of the sulfidization products. During sulfidization, Cu(II) species on the mineral surface were reduced into Cu(I) species, and the percentages of S22- and Sn2- relative to the total S increased after modification, resulting in increased surface hydrophobicity. The results of zeta potential measurements showed that the ethanediamine-modified mineral surface adsorbed with more sulfide ion species was advantageous to the attachment of xanthate species, thereby improving malachite floatability. The proposed ethanediamine modification followed by sulfidization xanthate flotation exhibits potential for industrial application.

Bioavailability and stability of mercury sulfide in Armuchee (USA) soil

International Nuclear Information System (INIS)

Han, Fengxiang; Shiyab, Safwan; Su, Yi; Monts, David L.; Waggoner, Charles A.; Matta, Frank B.

2007-01-01

Because of the adverse effects of elemental mercury and mercury compounds upon human health, the U.S. Department of Energy (DOE) is engaged in an on-going effort to monitor and remediate mercury-contaminated DOE sites. In order to more cost effectively implement those extensive remediation efforts, it is necessary to obtain an improved understanding of the role that mercury and mercury compounds play in the ecosystem. We have conducted pilot scale experiments to study the bioavailability of mercury sulfide in an Armuchee (eastern US ) soil. The effects of plants and incubation time on chemical stability and bioavailability of HgS under simulated conditions of the ecosystem have been examined, as has the dynamics of the dissolution of mercury sulfide by various extractants. The results show that mercury sulfide in contaminated Armuchee soil was still to some extent bioavailable to plants. After planting, soil mercury sulfide is more easily dissolved by both 4 M and 12 M nitric acid than pure mercury sulfide reagent. Dissolution kinetics of soil mercury sulfide and pure chemical reagent by nitric acid are different. Mercury release by EDTA from HgS-contaminated soil increased with time of reaction and soil mercury level. Chelating chemicals increase the solubility and bioavailability of mercury in HgS-contaminated soil. (authors)

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

2017-04-01

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.

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.

Cohesive zone model of carbon nanotube-coated carbon fiber/polyester composites

International Nuclear Information System (INIS)

Agnihotri, Prabhat Kamal; Kar, Kamal K; Basu, Sumit

2012-01-01

It has been previously reported that the average properties of carbon nanotube-coated carbon fiber/polyester multiscale composites critically depend on the length and density of nanotubes on the fiber surface. In this paper the effect of nanotube length and density on the interfacial properties of the carbon nanotube-coated carbon fiber–polymer interface has been studied using shear lag and a cohesive zone model. The latter model incorporates frictional sliding after complete debonding between the fiber and matrix and has been developed to quantify the effect of nanotube coating on various interfacial characterizing parameters. Our numerical results indicate that fibers with an optimal coverage and length of nanotubes significantly increase the interfacial strength and friction between the fiber and polymer. However, they also embrittle the interface compared with bare fibers. (paper)

Investigation of translaminar fracture in fibrereinforced composite laminates---applicability of linear elastic fracture mechanics and cohesive-zone model

Science.gov (United States)

Hou, Fang

With the extensive application of fiber-reinforced composite laminates in industry, research on the fracture mechanisms of this type of materials have drawn more and more attentions. A variety of fracture theories and models have been developed. Among them, the linear elastic fracture mechanics (LEFM) and cohesive-zone model (CZM) are two widely-accepted fracture models, which have already shown applicability in the fracture analysis of fiber-reinforced composite laminates. However, there remain challenges which prevent further applications of the two fracture models, such as the experimental measurement of fracture resistance. This dissertation primarily focused on the study of the applicability of LEFM and CZM for the fracture analysis of translaminar fracture in fibre-reinforced composite laminates. The research for each fracture model consisted of two sections: the analytical characterization of crack-tip fields and the experimental measurement of fracture resistance parameters. In the study of LEFM, an experimental investigation based on full-field crack-tip displacement measurements was carried out as a way to characterize the subcritical and steady-state crack advances in translaminar fracture of fiber-reinforced composite laminates. Here, the fiber-reinforced composite laminates were approximated as anisotropic solids. The experimental investigation relied on the LEFM theory with a modification with respect to the material anisotropy. Firstly, the full-field crack-tip displacement fields were measured by Digital Image Correlation (DIC). Then two methods, separately based on the stress intensity approach and the energy approach, were developed to measure the crack-tip field parameters from crack-tip displacement fields. The studied crack-tip field parameters included the stress intensity factor, energy release rate and effective crack length. Moreover, the crack-growth resistance curves (R-curves) were constructed with the measured crack-tip field parameters

Quantitative prediction process and evaluation method for seafloor polymetallic sulfide resources

Directory of Open Access Journals (Sweden)

Mengyi Ren

2016-03-01

Full Text Available Seafloor polymetallic sulfide resources exhibit significant development potential. In 2011, China received the exploration rights for 10,000 km2 of a polymetallic sulfides area in the Southwest Indian Ocean; China will be permitted to retain only 25% of the area in 2021. However, an exploration of seafloor hydrothermal sulfide deposits in China remains in the initial stage. According to the quantitative prediction theory and the exploration status of seafloor sulfides, this paper systematically proposes a quantitative prediction evaluation process of oceanic polymetallic sulfide resources and divides it into three stages: prediction in a large area, prediction in the prospecting region, and the verification and evaluation of targets. The first two stages of the prediction process have been employed in seafloor sulfides prospecting of the Chinese contract area. The results of stage one suggest that the Chinese contract area is located in the high posterior probability area, which indicates good prospecting potential area in the Indian Ocean. In stage two, the Chinese contract area of 48°–52°E has the highest posterior probability value, which can be selected as the reserved region for additional exploration. In stage three, the method of numerical simulation is employed to reproduce the ore-forming process of sulfides to verify the accuracy of the reserved targets obtained from the three-stage prediction. By narrowing the exploration area and gradually improving the exploration accuracy, the prediction will provide a basis for the exploration and exploitation of seafloor polymetallic sulfide resources.

New cyclic sulfides, garlicnins I2, M, N, and O, from Allium sativum.

Science.gov (United States)

Nohara, Toshihiro; Ono, Masateru; Nishioka, Naho; Masuda, Fuka; Fujiwara, Yukio; Ikeda, Tsuyoshi; Nakano, Daisuke; Kinjo, Junei

2018-01-01

One atypical thiolane-type sulfide, garlicnin I 2 (1), two 3,4-dimethylthiolane-type sulfides, garlicnins M (2) and N (3), and one thiabicyclic-type sulfide, garlicnin O (4), were isolated from the acetone extracts of Chinese garlic bulbs, Allium sativum and their structures were characterized. Hypothetical pathways for the production of the respective sulfides were discussed.

Nial and Nial-Based Composites Directionally Solidified by a Containerless Zone Process. Ph.D. Thesis

Science.gov (United States)

Joslin, Steven M.

1995-01-01

A containerless electromagnetically levitated zone (CELZ) process has been used to directionally solidify NiAl and NiAl-based composites. The CELZ processing results in single crystal NiAl (HP-NiAl) having higher purity than commercially pure NiAl grown by a modified Bridgman process (CP-NiAl). The mechanical properties, specifically fracture toughness and creep strength, of the HP-NiAl are superior to binary CP-NiAl and are used as a base-line for comparison with the composite materials subsequently studied. Two-phase composite materials (NiAl-based eutectic alloys) show improvement in room temperature fracture toughness and 1200 to 1400 K creep strength over that of binary HP-NiAl. Metallic phase reinforcements produce the greatest improvement in fracture toughness, while intermetallic reinforcement produces the largest improvement in high temperature strength. Three-phase eutectic alloys and composite materials were identified and directionally solidified with the intent to combine the improvements observed in the two-phase alloys into one alloy. The room temperature fracture toughness and high temperature strength (in air) serve as the basis for comparison between all of the alloys. Finally, the composite materials are discussed in terms of dominant fracture mechanism observed by fractography.

Laboratory studies of Aedes aegypti (L.) attraction to ketones, sulfides and primary chloroalkanes tested alone and in combination with l-lactic acid

Science.gov (United States)

The attraction of female Aedes aegypti to single compounds and binary compositions comprised of L-lactic acid and an additional saturated compound from a set of ketones, sulfides, and chloroalkanes was studied using a triple-cage dual-port olfactometer. These chemical classes were studied because o...

Enhanced performance of denitrifying sulfide removal process under micro-aerobic condition

International Nuclear Information System (INIS)

Chen Chuan; Ren Nanqi; Wang Aijie; Liu Lihong; Lee, Duu-Jong

2010-01-01

The denitrifying sulfide removal (DSR) process with bio-granules comprising both heterotrophic and autotrophic denitrifiers can simultaneously convert nitrate, sulfide and acetate into di-nitrogen gas, elementary sulfur and carbon dioxide, respectively, at high loading rates. This study determines the reaction rate of sulfide oxidized into sulfur, as well as the reduction of nitrate to nitrite, would be enhanced under a micro-aerobic condition. The presence of limited oxygen mitigated the inhibition effects of sulfide on denitrifier activities, and enhanced the performance of DSR granules. The advantages and disadvantages of applying the micro-aerobic condition to the DSR process are discussed.

Adaptation of cyanobacteria to the sulfide-rich microenvironment of black band disease of coral.

Science.gov (United States)

Myers, Jamie L; Richardson, Laurie L

2009-02-01

Black band disease (BBD) is a cyanobacteria-dominated microbial mat that migrates across living coral colonies lysing coral tissue and leaving behind exposed coral skeleton. The mat is sulfide-rich due to the presence of sulfate-reducing bacteria, integral members of the BBD microbial community, and the sulfide they produce is lethal to corals. The effect of sulfide, normally toxic to cyanobacteria, on the photosynthetic capabilities of five BBD cyanobacterial isolates of the genera Geitlerinema (3), Leptolyngbya (1), and Oscillatoria (1) and six non-BBD cyanobacteria of the genera Leptolyngbya (3), Pseudanabaena (2), and Phormidium (1) was examined. Photosynthetic experiments were performed by measuring the photoincorporation of [(14)C] NaHCO(3) under the following conditions: (1) aerobic (no sulfide), (2) anaerobic with 0.5 mM sulfide, and (3) anaerobic with 0.5 mM sulfide and 10 microM 3-(3',4'-dichlorophenyl)-1,1-dimethylurea (DCMU). All five BBD cyanobacterial isolates tolerated sulfide by conducting sulfide-resistant oxygenic photosynthesis. Five of the non-BBD cyanobacterial isolates did not tolerate sulfide, although one Pseudanabaena isolate continued to photosynthesize in the presence of sulfide at a considerably reduced rate. None of the isolates conducted anoxygenic photosynthesis with sulfide as an electron donor. This is the first report on the physiology of a culture of Oscillatoria sp. found globally in BBD.

Hydrogen sulfide intervention in focal cerebral ischemia/reperfusion injury in rats

Directory of Open Access Journals (Sweden)

Xin-juan Li

2015-01-01

Full Text Available The present study aimed to explore the mechanism underlying the protective effects of hydrogen sulfide against neuronal damage caused by cerebral ischemia/reperfusion. We established the middle cerebral artery occlusion model in rats via the suture method. Ten minutes after middle cerebral artery occlusion, the animals were intraperitoneally injected with hydrogen sulfide donor compound sodium hydrosulfide. Immunofluorescence revealed that the immunoreactivity of P2X 7 in the cerebral cortex and hippocampal CA1 region in rats with cerebral ischemia/reperfusion injury decreased with hydrogen sulfide treatment. Furthermore, treatment of these rats with hydrogen sulfide significantly lowered mortality, the Longa neurological deficit scores, and infarct volume. These results indicate that hydrogen sulfide may be protective in rats with local cerebral ischemia/reperfusion injury by down-regulating the expression of P2X 7 receptors.

Pb and Sr isotopic systematics of some basalts and sulfides from the East Pacific Rise at 21/sup 0/N (project RITA)

Energy Technology Data Exchange (ETDEWEB)

Vidal, P. (Centre National de la Recherche Scientifique, 35 - Rennes (France). Centre Armoricain d' Etude Structurale des Socles); Clauer, N. (Centre National de la Recherche Scientifique, 67 - Strasbourg (France). Centre de Sedimentologie et Geochimie de la Surface)

1981-10-01

Tholeiitic basalts and sulfide deposits from the 'Cyana' and 'Alvin' diving programs (RITA project) on the East Pacific Rise were analyzed for Pb and Sr isotopes. The basalt data plot within the field defined previously by other East Pacific Rise basalts (/sup 206/Pb//sup 204/Pb: 18.35-18.58; /sup 207/Pb//sup 204/Pb: 15.48-15.53; /sup 208/Pb//sup 204/Pb: 37.8-38.1; /sup 87/Sr//sup 86/Sr: 0.7022-0.7025). Pb, U and Sr contents (approx. equal to 0.5, approx. equal to 0.05 and approx. equal to 110 ppm, respectively) and ..mu.. values (approx. equal to 6) are typical of MORB, whereas Th/U ratios (approx. equal to 3.5) are significantly higher. The Pb isotopic ratios of the sulfide samples are very homogeneous (/sup 206/Pb//sup 204/Pb approx. equal to 18.47, /sup 207/Pb//sup 204/Pb approx. equal to 15.49, /sup 208/Pb//sup 204/Pb approx. equal to 37.90), and plot in the middle of the basalt field. This indicates that the sulfide Pb was derived from the basaltic crust without any significant contribution from either seawater or hemipelagic sediments, and the solutions from which the sulfiedes were deposited had uniform Pb isotopic composition. The Pb contents of three sulfide samples is relatively high (170-1310 ppm). The Sr contents of five sulfide samples are widely scattered from 12 to 210 ppm, with /sup 87/Sr//sup 86/Sr ratios intermediate between basaltic and seawater values (0.70554 +- 0.00005 to 0.70795 +- 0.00011). Leaching experiments show that both basalt-derived Sr and seawater Sr were present in the solutions which deposited the sulfides. In some cases, Sr was also adsorbed from seawater onto the sulfides following their deposition. Basalt-derived Sr and seawater Sr are also present in associated non-sulfide phases.

Nanostructured silver sulfide: synthesis of various forms and their application

Science.gov (United States)

Sadovnikov, S. I.; Rempel, A. A.; Gusev, A. I.

2018-04-01

The results of experimental studies on nanostructured silver sulfide are analyzed and generalized. The influence of small particle size on nonstoichiometry of silver sulfide is discussed. Methods for the synthesis of various forms of nanostructured Ag2S including nanopowders, stable colloidal solutions, quantum dots, core–shell nanoparticles and heteronanostructures are described. The advantages and drawbacks of different synthetic procedures are analyzed. Main fields of application of nanostructured silver sulfide are considered. The bibliography includes 184 references.

Radiation-induced physical ageing in network arsenic-sulfide/selenide glasses

International Nuclear Information System (INIS)

Shpotyuk, M; Golovchak, R; Kozdras, A; Shpotyuk, O

2010-01-01

Effect of radiation-induced physical ageing is investigated by differential scanning calorimetry method in As x Se 100-x (10 ≤ x ≤ 42) and As x S 100-x (30 ≤ x ≤ 42) glasses. Obtained results are compared with conventional physical ageing at normal conditions. Significant radiation-induced physical ageing is recorded for glassy As x S 100-x within 30 ≤ x x Se 100-x glasses from the same compositional interval do not show any measurable changes in DSC curves after γ-irradiation. Observed difference in radiation-induced physical ageing in arsenic-sulfide/selenide glasses is explained by a greater lifetime of γ-induced excitations within sulfur-based network in comparison with selenium-based one.

Production and Preservation of Sulfide Layering in Mercury's Magma Ocean

Science.gov (United States)

Boukare, C.-E.; Parman, S. W.; Parmentier, E. M.; Anzures, B. A.

2018-05-01

Mercury's magma ocean (MMO) would have been sulfur-rich. At some point during MMO solidification, it likely became sulfide saturated. Here we present physiochemical models exploring sulfide layer formation and stability.

Effects of Wood Pollution on Pore-Water Sulfide Levels and Eelgrass Germination

Science.gov (United States)

Ekelem, C.

2016-02-01

Historically, sawmills released wood waste onto coastal shorelines throughout the Pacific Northwest of the USA, enriching marine sediments with organic material. The increase in organic carbon boosts the bacterial reduction of sulfate and results in the production of a toxic metabolite, hydrogen sulfide. Hydrogen sulfide is a phytotoxin and can decrease the growth and survival of eelgrass. This is a critical issue since eelgrass, Zostera marina, forms habitat for many species, stabilizes sediment, and plays a role in nutrient cycling and sediment chemistry. The objective of our study was to determine the effects of wood debris on sediment pore-water hydrogen sulfide concentrations and eelgrass germination. To test the impact of wood inputs on sulfide production and seed germination, we conducted a laboratory mesocosm experiment, adding sawdust to marine sediments and measuring the sulfide levels weekly. We subsequently planted seeds in the mesocosms and measured germination rates. Higher concentrations of sawdust led to higher levels of pore-water hydrogen sulfide and drastically slower eelgrass germination rates. Treatments with greater than 10% wood enrichment developed free sulfide concentrations of 0.815 (± 0.427) mM after 118 days, suggesting sediments with greater than 10% wood pollution may have threateningly high pore-water hydrogen sulfide levels. These results can be used to set thresholds for remediation efforts and guide seed distribution in wood polluted areas.

Activation mechanism of ammonium ions on sulfidation of malachite (-201) surface by DFT study

Science.gov (United States)

Wu, Dandan; Mao, Yingbo; Deng, Jiushuai; Wen, Shuming

2017-07-01

The activation mechanism of ammonium ions on the sulfidation of malachite (-201) was determined by density functional theory (DFT) calculations. Results of DFT calculations indicated that interlayer sulfidation occurs during the sulfidation process of malachite (-201). The absorption of both the ammonium ion and sulfide ion on the malachite (-201) surface is stronger than that of sulfur ion. After sulfidation was activated with ammonium ion, the Cu 3d orbital peak is closer to the Fermi level and characterized by a stronger peak value. Therefore, the addition of ammonium ions activated the sulfidation of malachite (-201), thereby improving the flotation performance.

Study on the sulfidation behavior of smithsonite

International Nuclear Information System (INIS)

Wu, Dandan; Wen, Shuming; Deng, Jiushuai; Liu, Jian; Mao, Yingbo

2015-01-01

Highlights: • Zeta potential showed that the pH IEP of smithsonite decreased from 7.7 to 6. • ICP test showed the gradual reduction of C S in the solution. • SEM showed that the mineral surface was partially changed to ZnS film. • XPS indicated that the presence of a characteristic signal peak of sulfur ions. - Abstract: Zinc extraction from low-grade mineral resources of oxidized zinc has recently become a focus of study. Sulfidation is an important process in oxidized ore flotation. In this study, the influence of sulfur ion adsorption on smithsonite surface was investigated with the use of zeta potential, inductively coupled plasma (ICP), scanning electron microscope (SEM), and X-ray photoelectron spectroscopic studies. Zeta potential measurements of sodium sulfide showed that sulfur ions were adsorbed onto the surface of pure smithsonite, as evidenced by the increased negative charge and the decrease in the pH IEP of smithsonite from 7.7 to 6 after sodium sulfide treatment. The ICP test revealed the gradual reduction in sulfur ion adsorption onto the surface of smithsonite in pulp sulfur. After 30 min of absorption, C S in the solution declined from 1000 × 10 −6 mol/L to 1.4 × 10 −6 mol/L. SEM results showed that the mineral surface was partially changed to ZnS film after sodium sulfide treatment, whereas EDS analysis results showed that 2% S is contained on the smithsonite surface. X-ray photoelectron spectroscopy results indicated the presence of a characteristic signal peak of sulfur ions after sulfidation. Sulfur concentration increased to 11.89%, whereas oxygen concentration decreased from 42.31% to 13.74%. Sulfur ions were not only present during chemical adsorption, but were also incorporated into the crystal lattices of minerals by the exchange reaction between S 2− and CO 3 2− ions

Metal sulfide electrodes and energy storage devices thereof

Science.gov (United States)

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.

Development of novel and sensitive methods for the determination of sulfide in aqueous samples by hydrogen sulfide generation-inductively coupled plasma-atomic emission spectroscopy.

Science.gov (United States)

Colon, M; Todolí, J L; Hidalgo, M; Iglesias, M

2008-02-25

Two new, simple and accurate methods for the determination of sulfide (S(2-)) at low levels (microgL(-1)) in aqueous samples were developed. The generation of hydrogen sulfide (H(2)S) took place in a coil where sulfide reacted with hydrochloric acid. The resulting H(2)S was then introduced as a vapor into an inductively coupled plasma-atomic emission spectrometer (ICP-AES) and sulfur emission intensity was measured at 180.669nm. In comparison to when aqueous sulfide was introduced, the introduction of sulfur as H(2)S enhanced the sulfur signal emission. By setting a gas separator at the end of the reaction coil, reduced sulfur species in the form of H(2)S were removed from the water matrix, thus, interferences could be avoided. Alternatively, the gas separator was replaced by a nebulizer/spray chamber combination to introduce the sample matrix and reagents into the plasma. This methodology allowed the determination of both sulfide and sulfate in aqueous samples. For both methods the linear response was found to range from 5microgL(-1) to 25mgL(-1) of sulfide. Detection limits of 5microgL(-1) and 6microgL(-1) were obtained with and without the gas separator, respectively. These new methods were evaluated by comparison to the standard potentiometric method and were successfully applied to the analysis of reduced sulfur species in environmental waters.

Development of novel and sensitive methods for the determination of sulfide in aqueous samples by hydrogen sulfide generation-inductively coupled plasma-atomic emission spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Colon, M. [Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain); Departamento de Quimica Analitica, Nutricion y Bromatologia, University of Alicante, 03080 Alicante (Spain); Todoli, J.L. [Departamento de Quimica Analitica, Nutricion y Bromatologia, University of Alicante, 03080 Alicante (Spain); Hidalgo, M. [Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain); Iglesias, M. [Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain)], E-mail: monica.iglesias@udg.es

2008-02-25

Two new, simple and accurate methods for the determination of sulfide (S{sup 2-}) at low levels ({mu}g L{sup -1}) in aqueous samples were developed. The generation of hydrogen sulfide (H{sub 2}S) took place in a coil where sulfide reacted with hydrochloric acid. The resulting H{sub 2}S was then introduced as a vapor into an inductively coupled plasma-atomic emission spectrometer (ICP-AES) and sulfur emission intensity was measured at 180.669 nm. In comparison to when aqueous sulfide was introduced, the introduction of sulfur as H{sub 2}S enhanced the sulfur signal emission. By setting a gas separator at the end of the reaction coil, reduced sulfur species in the form of H{sub 2}S were removed from the water matrix, thus, interferences could be avoided. Alternatively, the gas separator was replaced by a nebulizer/spray chamber combination to introduce the sample matrix and reagents into the plasma. This methodology allowed the determination of both sulfide and sulfate in aqueous samples. For both methods the linear response was found to range from 5 {mu}g L{sup -1} to 25 mg L{sup -1} of sulfide. Detection limits of 5 {mu}g L{sup -1} and 6 {mu}g L{sup -1} were obtained with and without the gas separator, respectively. These new methods were evaluated by comparison to the standard potentiometric method and were successfully applied to the analysis of reduced sulfur species in environmental waters.

Pathways of sulfate and hydrogen sulfide transformations in a BTEX- contaminated groundwater system

DEFF Research Database (Denmark)

Einsiedl, Florian; Anneser, B.; Griebler, C.

2010-01-01

in complex environmental systems. As a result, compound specific stable isotope signatures in various sulfur species were determined in a tar-oil contaminated site and were linked to the microbial community distribution in the aquifer. The goal of the study was to reach an integrated understanding of sulfur...... intermediate during abiotic oxidation of hydrogen sulphide, with the latter formed during bacterial sulfate reduction. The formed elemental sulfur may be used by the specific microbial community found in this aquifer for the oxidation of organic contaminants such as toluene. In contrast, reoxidation...... of hydrogen sulfide to sulfate by molecular oxygen may affect sulfur cycling within the transition between the unsaturated and the saturated zones and therefore attenuate concentrations of contaminants in groundwater as well....

Nano Transition Metal Sulfide Catalyst for Solvolysis Liquefaction of Soda Lignin

International Nuclear Information System (INIS)

Fei-Ling, P.; Chin-Hua, C.; Sarani Zakaria; Soon-Keong, N.; Tze-Khong, L.

2011-01-01

Solvolysis liquefaction of soda lignin in the presence of various transition metal sulfide catalysts was studied to investigate the catalyst effects on the oil and gas yields, conversion rate and higher heating value (HHV) of oil. Nano sized copper sulfide, iron sulfide and molybdenum sulfide were successfully synthesized via a simple hydrothermal method under reaction temperature 200 degree Celsius for 90 min. The addition of transition metal sulfide based catalysts (CuS, MoS 2 and FeS 2 ) enhanced both production of the oils and gas and the higher heating value (HHV) of oil products. A high oil and gas yields of 82.1 % and 2890 cm 3 was obtained with MoS 2 at 250 degree Celsius for 60 min. Elemental analyses for the oils revealed that the liquid products have much higher heating values than the crude soda lignin powder. (author)

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., 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 be considered when addressing mercury biogeochemistry.

Enhanced performance of denitrifying sulfide removal process under micro-aerobic condition.

Science.gov (United States)

Chen, Chuan; Ren, Nanqi; Wang, Aijie; Liu, Lihong; Lee, Duu-Jong

2010-07-15

The denitrifying sulfide removal (DSR) process with bio-granules comprising both heterotrophic and autotrophic denitrifiers can simultaneously convert nitrate, sulfide and acetate into di-nitrogen gas, elementary sulfur and carbon dioxide, respectively, at high loading rates. This study determines the reaction rate of sulfide oxidized into sulfur, as well as the reduction of nitrate to nitrite, would be enhanced under a micro-aerobic condition. The presence of limited oxygen mitigated the inhibition effects of sulfide on denitrifier activities, and enhanced the performance of DSR granules. The advantages and disadvantages of applying the micro-aerobic condition to the DSR process are discussed. 2010 Elsevier B.V. All rights reserved.

Shifts in coastal sediment oxygenation cause pronounced changes in microbial community composition and associated metabolism.

Science.gov (United States)

Broman, Elias; Sjöstedt, Johanna; Pinhassi, Jarone; Dopson, Mark

2017-08-09

A key characteristic of eutrophication in coastal seas is the expansion of hypoxic bottom waters, often referred to as 'dead zones'. One proposed remediation strategy for coastal dead zones in the Baltic Sea is to mix the water column using pump stations, circulating oxygenated water to the sea bottom. Although microbial metabolism in the sediment surface is recognized as key in regulating bulk chemical fluxes, it remains unknown how the microbial community and its metabolic processes are influenced by shifts in oxygen availability. Here, coastal Baltic Sea sediments sampled from oxic and anoxic sites, plus an intermediate area subjected to episodic oxygenation, were experimentally exposed to oxygen shifts. Chemical, 16S rRNA gene, metagenomic, and metatranscriptomic analyses were conducted to investigate changes in chemistry fluxes, microbial community structure, and metabolic functions in the sediment surface. Compared to anoxic controls, oxygenation of anoxic sediment resulted in a proliferation of bacterial populations in the facultative anaerobic genus Sulfurovum that are capable of oxidizing toxic sulfide. Furthermore, the oxygenated sediment had higher amounts of RNA transcripts annotated as sqr, fccB, and dsrA involved in sulfide oxidation. In addition, the importance of cryptic sulfur cycling was highlighted by the oxidative genes listed above as well as dsvA, ttrB, dmsA, and ddhAB that encode reductive processes being identified in anoxic and intermediate sediments turned oxic. In particular, the intermediate site sediments responded differently upon oxygenation compared to the anoxic and oxic site sediments. This included a microbial community composition with more habitat generalists, lower amounts of RNA transcripts attributed to methane oxidation, and a reduced rate of organic matter degradation. These novel data emphasize that genetic expression analyses has the power to identify key molecular mechanisms that regulate microbial community responses

Succession of Bacterial Communities in a Seasonally Stratified Lake with an Anoxic and Sulfidic Hypolimnion

Directory of Open Access Journals (Sweden)

Muhe Diao

2017-12-01

Full Text Available Although bacteria play key roles in aquatic food webs and biogeochemical cycles, information on the seasonal succession of bacterial communities in lakes is still far from complete. Here, we report results of an integrative study on the successional trajectories of bacterial communities in a seasonally stratified lake with an anoxic hypolimnion. The bacterial community composition of epilimnion, metalimnion, and hypolimnion diverged during summer stratification and converged when the lake was mixed. In contrast, bacterial communities in the sediment remained relatively stable over the year. Phototrophic Cyanobacteria and heterotrophic Actinobacteria, Alphaproteobacteria and Planktomycetes were abundant in the aerobic epilimnion, Gammaproteobacteria (mainly Chromatiaceae dominated in the metalimnion, and Chlorobi, Betaproteobacteria, Deltaproteobacteria, and Firmicutes were abundant in the anoxic sulfidic hypolimnion. Anoxic but nonsulfidic conditions expanded to the surface layer during fall turnover, when the epilimnion, metalimnion and upper hypolimnion mixed. During this period, phototrophic sulfur bacteria (Chromatiaceae and Chlorobi disappeared, Polynucleobacter (Betaproteobacteria and Methylobacter (Gammaproteobacteria spread out from the former meta- and hypolimnion to the surface layer, and Epsilonproteobacteria dominated in the bottom water layer. Cyanobacteria and Planktomycetes regained dominance in early spring, after the oxygen concentration was restored by winter mixing. In total, these results show large spatio-temporal changes in bacterial community composition, especially during transitions from oxic to anoxic and from sulfidic to nonsulfidic conditions.

Fuel conditioning facility zone-to-zone transfer administrative controls

International Nuclear Information System (INIS)

Pope, C. L.

2000-01-01

The administrative controls associated with transferring containers from one criticality hazard control zone to another in the Argonne National Laboratory (ANL) Fuel Conditioning Facility (FCF) are described. FCF, located at the ANL-West site near Idaho Falls, Idaho, is used to remotely process spent sodium bonded metallic fuel for disposition. The process involves nearly forty widely varying material forms and types, over fifty specific use container types, and over thirty distinct zones where work activities occur. During 1999, over five thousand transfers from one zone to another were conducted. Limits are placed on mass, material form and type, and container types for each zone. Ml material and containers are tracked using the Mass Tracking System (MTG). The MTG uses an Oracle database and numerous applications to manage the database. The database stores information specific to the process, including material composition and mass, container identification number and mass, transfer history, and the operators involved in each transfer. The process is controlled using written procedures which specify the zone, containers, and material involved in a task. Transferring a container from one zone to another is called a zone-to-zone transfer (ZZT). ZZTs consist of four distinct phases, select, request, identify, and completion

The effect of sulfate concentration on (sub)millimeter-scale sulfide δ 34S in hypersaline cyanobacterial mats over the diurnal cycle

Science.gov (United States)

Fike, David A.; Finke, Niko; Zha, Jessica; Blake, Garrett; Hoehler, Tori M.; Orphan, Victoria J.

2009-10-01

Substantial isotopic fractionations are associated with many microbial sulfur metabolisms and measurements of the bulk δ 34S isotopic composition of sulfur species (predominantly sulfates and/or sulfides) have been a key component in developing our understanding of both modern and ancient biogeochemical cycling. However, the interpretations of bulk δ 34S measurements are often non-unique, making reconstructions of paleoenvironmental conditions or microbial ecology challenging. In particular, the link between the μm-scale microbial activity that generates isotopic signatures and their eventual preservation as a bulk rock value in the geologic record has remained elusive, in large part because of the difficulty of extracting sufficient material at small scales. Here we investigate the potential for small-scale (˜100 μm-1 cm) δ 34S variability to provide additional constraints for environmental and/or ecological reconstructions. We have investigated the impact of sulfate concentrations (0.2, 1, and 80 mM SO 4) on the δ 34S composition of hydrogen sulfide produced over the diurnal (day/night) cycle in cyanobacterial mats from Guerrero Negro, Baja California Sur, Mexico. Sulfide was captured as silver sulfide on the surface of a 2.5 cm metallic silver disk partially submerged beneath the mat surface. Subsequent analyses were conducted on a Cameca 7f-GEO secondary ion mass spectrometer (SIMS) to record spatial δ 34S variability within the mats under different environmental conditions. Isotope measurements were made in a 2-dimensional grid for each incubation, documenting both lateral and vertical isotopic variation within the mats. Typical grids consisted of ˜400-800 individual measurements covering a lateral distance of ˜1 mm and a vertical depth of ˜5-15 mm. There is a large isotopic enrichment (˜10-20‰) in the uppermost mm of sulfide in those mats where [SO 4] was non-limiting (field and lab incubations at 80 mM). This is attributed to rapid recycling of

Sulfidization of an aluminocobaltomolybdenum catalyst using the 35S radioisotope

International Nuclear Information System (INIS)

Isagulyants, G.V.; Greish, A.A.; Kogan, V.M.

1987-01-01

It has been established that in aluminocobaltomolybdenum catalyst sulfidized with elemental sulfur there are two types of sulfur, free and bound. The maximum amount of bound sulfur in ACM catalyst is 6.6 wt. %, which corresponds to practically complete sulfidation of the ACM catalyst. In the presence of hydrogen an equilibrium distribution of bound sulfur is achieved in a granule of ACM catalyst irrespective of the temperature of sulfidation. In a nitrogen atmosphere it is primarily the surface layers of the catalyst that are sulfured

Microbial selenium sulfide reduction for selenium recovery from wastewater

NARCIS (Netherlands)

Hageman, S.P.W.; Weijden, van der R.D.; Stams, A.J.M.; Cappellen, van P.; Buisman, C.J.N.

2017-01-01

Microbial reduction of selenium sulfide (SeS2) is a key step in a new treatment process to recover selenium from selenate and selenite streams. In this process, selenate is first reduced to selenite, and subsequently selenite is reduced by sulfide and precipitates from the solution as SeS2. The

Study on the surface sulfidization behavior of smithsonite at high temperature

Science.gov (United States)

Lv, Jin-fang; Tong, Xiong; Zheng, Yong-xing; Xie, Xian; Wang, Cong-bing

2018-04-01

Surface sulfidization behavior of smithsonite at high temperature was investigated by X-ray powder diffractometer (XRD) along with thermodynamic calculation, X-ray photoelectron spectroscopy (XPS) and electron probe microanalysis (EPMA). The XRD and thermodynamic analyses indicated that the smithsonite was decomposed into zincite at high temperatures. After introducing a small amount of pyrite, artificial sulfides were formed at surface of the obtained zincite. The XPS analyses revealed that the sulfide species including zinc sulfide and zinc disulfide were generated at the zincite surface. The EPMA analyses demonstrated that the film of sulfides was unevenly distributed at the zincite surface. The average concentration of elemental sulfur at the sample surface increased with increasing of pyrite dosage. A suitable mole ratio of FeS2 to ZnCO3 for the surface thermal modification was determined to be about 0.3. These findings can provide theoretical support for improving the process during which the zinc recovery from refractory zinc oxide ores is achieved by xanthate flotation.

Isotopic composition of water in a deep unsaturated zone beside a radioactive-waste disposal area near Beatty, Nevada

Science.gov (United States)

Stonestrom, David A.; Prudic, David E.; Striegl, Robert G.; Morganwalp, David W.; Buxton, Herbert T.

1999-01-01

The isotopic composition of water in deep unsaturated zones is of interest because it provides information relevant to hydrologic processes and contaminant migration. Profiles of oxygen-18 (18O), deuterium (D), and tritium (3H) from a 110-meter deep unsaturated zone, together with data on the isotopic composition of ground water and modern-day precipitation, are interpreted in the context of water-content, water-potential, and pore-gas profiles. At depths greater than about three meters, water vapor and liquid water are in approximate equilibrium with respect to D and 18O. The vapor-phase concentrations of D and 18O have remained stable through repeated samplings. Vapor-phase 3H concentrations have generally increased with time, requiring synchronous sampling of liquid and vapor to assess equilibrium. Below 30 meters, concentrations of D and 18O in pore water become approximately equal to the composition of ground water, which is isotopically lighter than modern precipitation and has a carbon-14 (14C) concentration of about 26 percent modern carbon. These data indicate that net gradients driving fluxes of water, gas, and heat are directed upwards for undisturbed conditions at the Amargosa Desert Research Site (ADRS). Superimposed on the upward-directed flow field, tritium is migrating away from waste in response to gradients in tritium concentrations.

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.

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

2017-08-01

The sensitivity of wild rice (Zizania palustris) to sulfide is not well understood. Because sulfate in surface waters is reduced to sulfide by anaerobic bacteria in sediments and historical information indicated that 10 mg/L sulfate in Minnesota (USA) surface water reduced Z. palustris abundance, the Minnesota Pollution Control Agency established 10 mg/L sulfate as a water quality criterion in 1973. A 21-d daily-renewal hydroponic study was conducted to evaluate sulfide toxicity to wild rice and the potential mitigation of sulfide toxicity by iron (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 d after 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 d). The results indicate that exposure of developing wild rice to sulfide at ≥3.1 mg sulfide/L in the presence of 0.8 mg/L Fe reduced mesocotyl emergence. Sulfide toxicity was mitigated by the addition of Fe at 2.8 mg/L 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 taking into account factors that alter toxicity, including sediment Fe and organic carbon, are necessary. Environ Toxicol Chem 2017;36:2217-2226. © 2017 SETAC. © 2017 SETAC.

Hydrous Ferric Oxides in Sediment Catalyze Formation of Reactive Oxygen Species during Sulfide Oxidation

Directory of Open Access Journals (Sweden)

Sarah A. Murphy

2016-11-01

Full Text Available Abstract: This article describes the formation of reactive oxygen species as a result of the oxidation of dissolved sulfide by Fe(III-containing sediments suspended in oxygenated seawater over the pH range 7.00 and 8.25. Sediment samples were obtained from across the coastal littoral zone in South Carolina, US, at locations from the beach edge to the forested edge of a Spartina dominated estuarine salt marsh and suspended in aerated seawater. Reactive oxygen species (superoxide and hydrogen peroxide production was initiated in sediment suspensions by the addition of sodium bisulfide. The subsequent loss of HS-, formation of Fe(II (as indicated by Ferrozine, and superoxide and hydrogen peroxide were monitored over time. The concentration of superoxide rose from the baseline and then persisted at an apparent steady state concentration of approximately 500 nanomolar at pH 8.25 and 200 nanomolar at pH 7.00 respectively until >97% hydrogen sulfide was consumed. Measured superoxide was used to predict hydrogen peroxide yield based on superoxide dismutation. Dismutation alone quantitatively predicted hydrogen peroxide formation at pH 8.25 but over predicted hydrogen peroxide formation at pH 7 by a factor of approximately 102. Experiments conducted with episodic spikes of added hydrogen peroxide indicated rapid hydrogen peroxide consumption could account for its apparent low instantaneous yield, presumably the result of its reaction with Fe(II species, polysulfides or bisulfite. All sediment samples were characterized for total Fe, Cu, Mn, Ni, Co and hydrous ferric oxide by acid extraction followed by mass spectrometric or spectroscopic characterization. Sediments with the highest loadings of hydrous ferric oxide were the only sediments that produced significant dissolved Fe(II species or ROS as a result of sulfide exposure.

Sulfide phase in the Fe-Ti-S and Fe-C-Ti-S alloys

International Nuclear Information System (INIS)

Malinochka, Ya.N.; Balakina, N.A.; Shmelev, Yu.S.

1976-01-01

The nature of the sulfide phases in Fe-Ti-S and Fe-C-Ti-S alloys was studied. The carbide and the sulfide phase were identified the aid of X-ray spectral microanalysis. It was established that for a small content of titanium and sulfur in ternary Fe-Ti-S alloys the solidification of the γ-solution on the boundaries of dendritic branches is accompanied, along with the precipitation of a sulfide rich in iron of the (Fe, Ti) S type where a small quantity of titanium is dissolved, by the formation of a titanium-bearing sulfide eutectic γ + TiS. The amount of the sulfide eutectic increases with the contents of titanium and sulfur until a purely eutectic alloy is formed. Both carbides and sulfides may be formed in the solidification of quaternary alloys Fe-C-Ti-S

Preparation and characterization of amorphous manganese sulfide thin films by SILAR method

International Nuclear Information System (INIS)

Pathan, H.M.; Kale, S.S.; Lokhande, C.D.; Han, Sung-Hwan; Joo, Oh-Shim

2007-01-01

Manganese sulfide thin films were deposited by a simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method using manganese acetate as a manganese and sodium sulfide as sulfide ion sources, respectively. Manganese sulfide films were characterized for their structural, surface morphological and optical properties by means of X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and optical absorption measurement techniques. The as-deposited film on glass substrate was amorphous. The optical band gap of the film was found to be thickness dependent. As thickness increases optical band gap was found to be increase. The water angle contact was found to be 34 o , suggesting hydrophilic nature of manganese sulfide thin films. The presence of Mn and S in thin film was confirmed by energy dispersive X-ray analysis

76 FR 64022 - Hydrogen Sulfide; Community Right-to-Know Toxic Chemical Release Reporting

Science.gov (United States)

2011-10-17

... Hydrogen Sulfide; Community Right-to-Know Toxic Chemical Release Reporting AGENCY: Environmental Protection Agency (EPA). ACTION: Lifting of Administrative Stay for Hydrogen Sulfide. SUMMARY: EPA is announcing... (EPCRA) section 313 toxic chemical release reporting requirements for hydrogen sulfide (Chemical...

76 FR 69136 - Hydrogen Sulfide; Community Right-to-Know Toxic Chemical Release Reporting

Science.gov (United States)

2011-11-08

... Hydrogen Sulfide; Community Right-to-Know Toxic Chemical Release Reporting AGENCY: Environmental Protection Agency (EPA). ACTION: Lifting of Administrative Stay for Hydrogen Sulfide; Correction. SUMMARY: The... Administrative Stay of the reporting requirements for hydrogen sulfide. The Office of the Federal Register...

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.

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.; 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.

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 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.

The Complex Resistivity Spectrum Characteristics About Stratabound Sulfide Deposits

Science.gov (United States)

Dong, P.; Sun, B.; Wang, L.; Chen, Z.; Dong, Z.; Wu, Y.

2010-12-01

Complex resistivity method has become the key technique of deep prospecting, and widely applied in stratabound sulfide deposits which often form massive ores. However, the complex resistivity spectrum characteristics of stratabound sulfide deposits remains unknown. Through studying variation problem of two-dimensional polarization medium, deducing the differential equations and calculating formula,we applied Cole-Cole model to deduce the spectrum of complex resistivity based on the model of three-node and four-node finite element method, and programmed homologous procedure. We utilized the Earth Model of Geological Layers which has accurate analytical solution to test rationality and accuracy of our modeling. We applied the layer structure provided by drilling results in Chenmenshan copper mine,which is typical strata-bound sulfide deposits in Jiangxi province,China, and calculated the spectra of complex resistivity, then made comparison between modeled and measured values. We find good corellation between them. Our studies may have imporved the interpretation of complex resistivity data, which help apply complex resistivity methods of propecting on stratabound sulfide deposites.

Radiation-induced physical ageing in network arsenic-sulfide/selenide glasses

Energy Technology Data Exchange (ETDEWEB)

Shpotyuk, M; Golovchak, R; Kozdras, A; Shpotyuk, O, E-mail: shpotyuk@novas.lviv.ua

2010-11-15

Effect of radiation-induced physical ageing is investigated by differential scanning calorimetry method in As{sub x}Se{sub 100-x} (10 {<=} x {<=} 42) and As{sub x}S{sub 100-x} (30 {<=} x {<=} 42) glasses. Obtained results are compared with conventional physical ageing at normal conditions. Significant radiation-induced physical ageing is recorded for glassy As{sub x}S{sub 100-x} within 30 {<=} x < 40 range, while As{sub x}Se{sub 100-x} glasses from the same compositional interval do not show any measurable changes in DSC curves after {gamma}-irradiation. Observed difference in radiation-induced physical ageing in arsenic-sulfide/selenide glasses is explained by a greater lifetime of {gamma}-induced excitations within sulfur-based network in comparison with selenium-based one.

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

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......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...... of film formation in sulfide solutions was followed by video. It can be shown that capacitative and diffusional effects due to porous reactive deposits tend to dominate the data resulting in unreliable corrosion rates measured by electrochemical techniques. The effect is strongly increased if biofilm...

Study of radiation synovectomy using 188Re-sulfide

International Nuclear Information System (INIS)

Chen Gang; Li Peiyong; Jiang Xufeng; Zhang Liying; Wang Xuefeng; Sun Zhenming; Zhang Huan

2002-01-01

Objective: To study the radiation synovectomy with 188 Re-sulfide. Methods: Thirty cases were divided into 2 groups, the group with hemophilia and the group with rheumatoid arthritis (RA). Patients with joint synovitis were injected different doses of 188 Re-sulfide, 222 - 444 MBq intra-articular. MRI was taken before and 3 - 6 months after the radiation synovectomy to evaluate the treatment efficacy, and the symptoms were also evaluated. Results: MRI study showed that after the treatment the synovium became thiner and the edema was reduced in the lesioned joint. The symptoms were improved with the pain relieved and duration of intra-articular hemorrhage reduced. Conclusions: Radiation synovectomy using 188 Re-sulfide has effects on synovitis. It can be used clinically to improve the symptoms of joint synovitis and reduce the duration of intra-articular hemorrhage

Study on the sulfidation behavior of smithsonite

Energy Technology Data Exchange (ETDEWEB)

Wu, Dandan; Wen, Shuming, E-mail: shmwen@126.com; Deng, Jiushuai, E-mail: dengshuai689@163.com; Liu, Jian; Mao, Yingbo

2015-02-28

Highlights: • Zeta potential showed that the pH{sub IEP} of smithsonite decreased from 7.7 to 6. • ICP test showed the gradual reduction of C{sub S} in the solution. • SEM showed that the mineral surface was partially changed to ZnS film. • XPS indicated that the presence of a characteristic signal peak of sulfur ions. - Abstract: Zinc extraction from low-grade mineral resources of oxidized zinc has recently become a focus of study. Sulfidation is an important process in oxidized ore flotation. In this study, the influence of sulfur ion adsorption on smithsonite surface was investigated with the use of zeta potential, inductively coupled plasma (ICP), scanning electron microscope (SEM), and X-ray photoelectron spectroscopic studies. Zeta potential measurements of sodium sulfide showed that sulfur ions were adsorbed onto the surface of pure smithsonite, as evidenced by the increased negative charge and the decrease in the pH{sub IEP} of smithsonite from 7.7 to 6 after sodium sulfide treatment. The ICP test revealed the gradual reduction in sulfur ion adsorption onto the surface of smithsonite in pulp sulfur. After 30 min of absorption, C{sub S} in the solution declined from 1000 × 10{sup −6} mol/L to 1.4 × 10{sup −6} mol/L. SEM results showed that the mineral surface was partially changed to ZnS film after sodium sulfide treatment, whereas EDS analysis results showed that 2% S is contained on the smithsonite surface. X-ray photoelectron spectroscopy results indicated the presence of a characteristic signal peak of sulfur ions after sulfidation. Sulfur concentration increased to 11.89%, whereas oxygen concentration decreased from 42.31% to 13.74%. Sulfur ions were not only present during chemical adsorption, but were also incorporated into the crystal lattices of minerals by the exchange reaction between S{sup 2−} and CO{sub 3}{sup 2−} ions.

Novel Microbial Assemblages Dominate Weathered Sulfide-Bearing Rock from Copper-Nickel Deposits in the Duluth Complex, Minnesota, USA.

Science.gov (United States)

Jones, Daniel S; Lapakko, Kim A; Wenz, Zachary J; Olson, Michael C; Roepke, Elizabeth W; Sadowsky, Michael J; Novak, Paige J; Bailey, Jake V

2017-08-15

undeveloped source of copper and nickel on Earth. Microorganisms are important catalysts for sulfide mineral oxidation, and research on extreme acidophiles has improved our ability to manage and remediate mine wastes. We found that the microbial assemblages associated with weathered rock from the Duluth Complex are dominated by organisms not widely associated with mine waste or mining-impacted environments, and we describe geochemical and experimental influences on community composition. This report will be a useful foundation for understanding the microbial biogeochemistry of moderately acidic mine waste from these and similar deposits. Copyright © 2017 American Society for Microbiology.

Textural, compositional, and sulfur isotope variations of sulfide minerals in the Red Dog Zn-Pb-Ag deposits, Brooks Range, Alaska: Implications for Ore Formation

Science.gov (United States)

Kelley, K.D.; Leach, D.L.; Johnson, C.A.; Clark, J.L.; Fayek, M.; Slack, J.F.; Anderson, V.M.; Ayuso, R.A.; Ridley, W.I.

2004-01-01

The Red Dog Zn-Pb deposits are hosted in organic-rich mudstone and shale of the Mississippian Kuna Formation. A complex mineralization history is defined by four sphalerite types or stages: (1) early brown sphalerite, (2) yellow-brown sphalerite, (3) red-brown sphalerite, and (4) late tan sphalerite. Stages 2 and 3 constitute the main ore-forming event and are volumetrically the most important. Sulfides in stages 1 and 2 were deposited with barite, whereas stage 3 largely replaces barite. Distinct chemical differences exist among the different stages of sphalerite. From early brown sphalerite to later yellow-brown sphalerite and red-brown sphalerite, Fe and Co content generally increase and Mn and Tl content generally decrease. Early brown sphalerite contains no more than 1.9 wt percent Fe and 63 ppm Co, with high Mn (up to 37 ppm) and Tl (126 ppm), whereas yellow-brown sphalerite and red-brown sphalerite contain high Fe (up to 7.3 wt %) and Co (up to 382 ppm), and low Mn (ion microprobe sulfur isotope analyses show a progression from extremely low ??34S values for stage 1 (as low as -37.20???) to much higher values for yellow-brown sphalerite (mean of 3.3???; n = 30) and red-brown sphalerite (mean of 3.4; n = 20). Late tan sphalerite is isotopically light (-16.4 to -27.2???). The textural, chem ical, and isotopic data indicate the following paragenesis: (1) deposition of early brown sphalerite with abundant barite, minor pyrite, and trace galena immediately beneath the sea floor in unconsolidated mud; (2) deposition of yellow-brown sphalerite during subsea-floor hydrothermal recrystallization and coarsening of preexisting barite; (3) open-space deposition of barite, red-brown sphalerite and other sulfides in veins and coeval replacement of barite; and (4) postore sulfide deposition, including the formation of late tan sphalerite breccias. Stage 1 mineralization took place in a low-temperature environment where fluids rich in Ba mixed with pore water or water

Effects of sulfide treatment on electronic transport of graphene/n-type Si Schottky diodes

Energy Technology Data Exchange (ETDEWEB)

Zeng, Jian-Jhou; Lin, Yow-Jon, E-mail: rzr2390@yahoo.com.tw

2014-05-01

The present work reports the fabrication and detailed electrical properties of graphene/n-type Si Schottky diodes with and without sulfide treatment. The graphene/n-type Si Schottky diode without sulfide treatment shows a poor rectifying behavior with an ideality factor (η) of 4.2 and high leakage. η > 2 implies that the interfacial defects influence the electronic conduction through the device. However, the graphene/n-type Si Schottky diode with sulfide treatment for 5 min shows a good rectifying behavior with η of 1.8 and low leakage. Such an improvement indicates that a good passivation is formed at the interface as a result of the reduction of the defect density. These experimental demonstrations suggest that it may be possible to minimize the adverse effects of the interface states to obtain functional devices using sulfide treatment. In addition, the graphene/n-type Si Schottky diode with sulfide treatment for 10 min shows a poor rectifying behavior with η of 2.5 and high leakage. Note, a suitable sulfide treatment time is an important issue for improving the device performance. - Highlights: • Graphene/Si diodes with sulfide treatment for 5 min show a good rectifying behavior. • Graphene/Si diodes without sulfide treatment show a poor rectifying behavior. • The interfacial defects of Schottky diodes were controlled by sulfide treatment. • Such an improvement indicates that a good passivation is formed at the interface. • A suitable sulfide treatment time is an important issue for improving performances.

Effects of sulfide treatment on electronic transport of graphene/n-type Si Schottky diodes

International Nuclear Information System (INIS)

Zeng, Jian-Jhou; Lin, Yow-Jon

2014-01-01

The present work reports the fabrication and detailed electrical properties of graphene/n-type Si Schottky diodes with and without sulfide treatment. The graphene/n-type Si Schottky diode without sulfide treatment shows a poor rectifying behavior with an ideality factor (η) of 4.2 and high leakage. η > 2 implies that the interfacial defects influence the electronic conduction through the device. However, the graphene/n-type Si Schottky diode with sulfide treatment for 5 min shows a good rectifying behavior with η of 1.8 and low leakage. Such an improvement indicates that a good passivation is formed at the interface as a result of the reduction of the defect density. These experimental demonstrations suggest that it may be possible to minimize the adverse effects of the interface states to obtain functional devices using sulfide treatment. In addition, the graphene/n-type Si Schottky diode with sulfide treatment for 10 min shows a poor rectifying behavior with η of 2.5 and high leakage. Note, a suitable sulfide treatment time is an important issue for improving the device performance. - Highlights: • Graphene/Si diodes with sulfide treatment for 5 min show a good rectifying behavior. • Graphene/Si diodes without sulfide treatment show a poor rectifying behavior. • The interfacial defects of Schottky diodes were controlled by sulfide treatment. • Such an improvement indicates that a good passivation is formed at the interface. • A suitable sulfide treatment time is an important issue for improving performances

Sulfide Species Optical Monitoring by a Miniaturized Silicon Photomultiplier

Directory of Open Access Journals (Sweden)

Salvatore Petralia

2018-02-01

Full Text Available The monitoring of water-soluble pollutants is receiving a growing interest from the scientific community. In this context, sulfide anion species S2− and HS− are particularly relevant since they can cause acute and chronic toxicity including neurological effects and at high concentrations, even death. In this study, a new strategy for fast and sensitive optical detection of sulfide species in water samples is described. The method uses an integrated silicon photomultiplier (SiPM device coupled with the appropriate analytical strategy applied in a plastic microchip with dried reagents on board. More specifically, all sulfide species (H2S, HS− and S2− in water samples are detected by the fluorescence signal emitted upon the reaction with N,N-dimethyl-phenylenediamine sulfate in the presence of Fe3+, leading to the formation of the fluorescent methylene blue (MB species. It has been proven that the system herein proposed is able to measure sulfide concentration in a linear range from 0–10 mg L−1 with a sensitivity value of about 6.7 µA mg−1 L and a detection limit of 0.5 mg L−1. A comparison with conventional UV-Vis detection method has been also carried out. Data show a very good linear correlation (R2 = 0.98093, proving the effectiveness of the method. Results pave the way toward the development of portable and low-cost device systems for water-soluble sulfide pollutants.

Modelling of composite concrete block pavement systems applying a cohesive zone model

DEFF Research Database (Denmark)

Skar, Asmus; Poulsen, Peter Noe

This paper presents a numerical analysis of the fracture behaviour of the cement bound base material in composite concrete block pavement systems, using a cohesive zone model. The functionality of the proposed model is tested on experimental and numerical investigations of beam bending tests....... The pavement is modelled as a simple slab on grade structure and parameters influencing the response, such as analysis technique, geometry and material parameters are studied. Moreover, the analysis is extended to a real scale example, modelling the pavement as a three-layered structure. It is found...... block pavements. It is envisaged that the methodology implemented in this study can be extended and thereby contribute to the ongoing development of rational failure criteria that can replace the empirical formulas currently used in pavement engineering....

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...

Sorption of chromium(III) and chromium(VI) on lead sulfide

International Nuclear Information System (INIS)

Music, S.

1985-01-01

The sorption of chromium(III) and chromium(VI) on lead sulfide was investigated in dependence on pH, time of sorption, and on the concnetrations of sorbate and sorbent. The mechanisms of the sorption of Crsup(3+) and CrOsub(4)sup(2-) traces on lead sulfide are discussed; a difference between CrOsub(4)sup(2-) sorption on PbS and α-Fesub(2)Osub(3) was found. Sulfates and molybdates affect the removal of chromates from aqueous solutions. Lead sulfide carrier prepared in this work was also used for the preconcentration of chromium(III) and chromium(VI) from tap water. (author)

Magmatic-vapor expansion and the formation of high-sulfidation gold deposits: Chemical controls on alteration and mineralization

Science.gov (United States)

Henley, R.W.; Berger, B.R.

2011-01-01

Large bulk-tonnage high-sulfidation gold deposits, such as Yanacocha, Peru, are the surface expression of structurally-controlled lode gold deposits, such as El Indio, Chile. Both formed in active andesite-dacite volcanic terranes. Fluid inclusion, stable isotope and geologic data show that lode deposits formed within 1500. m of the paleo-surface as a consequence of the expansion of low-salinity, low-density magmatic vapor with very limited, if any, groundwater mixing. They are characterized by an initial 'Sulfate' Stage of advanced argillic wallrock alteration ?? alunite commonly with intense silicification followed by a 'Sulfide' Stage - a succession of discrete sulfide-sulfosalt veins that may be ore grade in gold and silver. Fluid inclusions in quartz formed during wallrock alteration have homogenization temperatures between 100 and over 500 ??C and preserve a record of a vapor-rich environment. Recent data for El Indio and similar deposits show that at the commencement of the Sulfide Stage, 'condensation' of Cu-As-S sulfosalt melts with trace concentrations of Sb, Te, Bi, Ag and Au occurred at > 600 ??C following pyrite deposition. Euhedral quartz crystals were simultaneously deposited from the vapor phase during crystallization of the vapor-saturated melt occurs to Fe-tennantite with progressive non-equilibrium fractionation of heavy metals between melt-vapor and solid. Vugs containing a range of sulfides, sulfosalts and gold record the changing composition of the vapor. Published fluid inclusion and mineralogical data are reviewed in the context of geological relationships to establish boundary conditions through which to trace the expansion of magmatic vapor from source to surface and consequent alteration and mineralization. Initially heat loss from the vapor is high resulting in the formation of acid condensate permeating through the wallrock. This Sulfate Stage alteration effectively isolates the expansion of magmatic vapor in subsurface fracture arrays

Surficial weathering of iron sulfide mine tailings under semi-arid climate.

Science.gov (United States)

Hayes, Sarah M; Root, Robert A; Perdrial, Nicolas; Maier, Raina; Chorover, Jon

2014-09-15

Mine wastes introduce anthropogenic weathering profiles to the critical zone that often remain unvegetated for decades after mining cessation. As such, they are vulnerable to wind and water dispersion of particulate matter to adjacent ecosystems and residential communities. In sulfide-rich ore tailings, propagation to depth of the oxidative weathering front controls the depth-variation in speciation of major and trace elements. Despite the prevalence of surficial mine waste deposits in arid regions of the globe, few prior studies have been conducted to resolve the near-surface profile of sulfide ore tailings weathered under semi-arid climate. We investigated relations between gossan oxidative reaction-front propagation and the molecular speciation of iron and sulfur in tailings subjected to weathering under semi-arid climate at an EPA Superfund Site in semi-arid central Arizona (USA). Here we report a multi-method data set combining wet chemical and synchrotron-based X-ray diffraction (XRD) and X-ray absorption near-edge spectroscopy (XANES) methods to resolve the tight coupling of iron (Fe) and sulfur (S) geochemical changes in the top 2 m of tailings. Despite nearly invariant Fe and S concentration with depth (130-140 and 100-120 g kg -1 , respectively), a sharp redox gradient and distinct morphological change was observed within the top 0.5 m, associated with a progressive oxidative alteration of ferrous sulfides to (oxyhydr)oxides and (hydroxy)sulfates. Transformation is nearly complete in surficial samples. Trends in molecular-scale alteration were co-located with a decrease in pH from 7.3 to 2.3, and shifts in Fe and S lability as measured via chemical extraction. Initial weathering products, ferrihydrite and gypsum, transform to schwertmannite, then jarosite-group minerals with an accompanying decrease in pH. Interestingly, thermodynamically stable phases such as goethite and hematite were not detected in any samples, but ferrihydrite was observed even in

Surficial weathering of iron sulfide mine tailings under semi-arid climate

Science.gov (United States)

Hayes, Sarah M.; Root, Robert A.; Perdrial, Nicolas; Maier, Raina M.; Chorover, Jon

2014-09-01

Mine wastes introduce anthropogenic weathering profiles to the critical zone that often remain unvegetated for decades after mining cessation. As such, they are vulnerable to wind and water dispersion of particulate matter to adjacent ecosystems and residential communities. In sulfide-rich ore tailings, propagation to depth of the oxidative weathering front controls the depth-variation in speciation of major and trace elements. Despite the prevalence of surficial mine waste deposits in arid regions of the globe, few prior studies have been conducted to resolve the near-surface profile of sulfide ore tailings weathered under semi-arid climate. We investigated relations between gossan oxidative reaction-front propagation and the molecular speciation of iron and sulfur in tailings subjected to weathering in a semi-arid climate at an EPA Superfund Site in central Arizona (USA). Here we report a multi-method data set combining wet chemical and synchrotron-based X-ray diffraction (XRD) and X-ray absorption near-edge spectroscopy (XANES) methods to resolve the tight coupling of iron (Fe) and sulfur (S) geochemical changes in the top 2 m of tailings. Despite nearly invariant Fe and S concentration with depth (130-140 and 100-120 g kg-1, respectively), a sharp redox gradient and distinct morphological change was observed within the top 0.5 m, associated with a progressive oxidative alteration of ferrous sulfides to (oxyhydr)oxides and (hydroxy)sulfates. Transformation is nearly complete in surficial samples. Trends in molecular-scale alteration were co-located with a decrease in pH from 7.3 to 2.3, and shifts in Fe and S lability as measured via chemical extraction. Initial weathering products, ferrihydrite and gypsum, transform to schwertmannite, then jarosite-group minerals with an accompanying decrease in pH. Interestingly, thermodynamically stable phases such as goethite and hematite were not detected in any samples, but ferrihydrite was observed even in samples with

Using a portable sulfide monitor as a motivational tool: a clinical study.

Science.gov (United States)

Uppal, Ranjit Singh; Malhotra, Ranjan; Grover, Vishakha; Grover, Deepak

2012-01-01

Bad breath has a significant impact on daily life of those who suffer from it. Oral malodor may rank only behind dental caries and periodontal disease as the cause of patient's visit to dentist. An aim of this study was to use a portable sulfide monitor as a motivational tool for encouraging the patients towards the better oral hygiene by correlating the plaque scores with sulfide monitor scores, and comparing the sulfide monitor scores before and after complete prophylaxis and 3 months after patient motivation. 30 patients with chronic periodontitis, having chief complaint of oral malodor participated in this study. At first visit, the plaque scores (P1) and sulfide monitor scores before (BCR1) and after complete oral prophylaxis (BCR2) were taken. Then the patients were motivated towards the better oral hygiene. After 3 months, plaque scores (P2) and sulfide monitor scores (BCR3) were recorded again. It was done using SPSS (student package software for statistical analysis). Paired sample test was performed. Statistically significant reduction in sulfide monitor scores was reported after the complete oral prophylaxis and 3 months after patient motivation. Plaque scores were significantly reduced after a period of 3 months. Plaque scores and breathchecker scores were positively correlated. An intensity of the oral malodor was positively correlated with the plaque scores. The portable sulfide monitor was efficacious in motivating the patients towards the better oral hygiene.

Corrosion of limestone tablets in sulfidic ground-water: measurements and speleogenetic implications

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Galdenzi Sandro

2012-07-01

Full Text Available The measurement of the weight loss in limestone tablets placed in the Grotta del Fiume (Frasassi, Italy provided data on the rate of limestone dissolution due to the sulfidic water and on the influence of local environmental conditions.A linear average corrosion rate of 24 mm ka-1 was measured in stagnant water, while the values were higher (68-119 mm ka-1 where the hydrologic conditions facilitate water movement and gas exchanges. In these zones the increase in water aggressivity is due to mixing with descending, O2-rich, seepage water and is also favored by easier gas exchange between ground-water and the cave atmosphere. Very intense corrosion was due to weakly turbulent flow, which caused evident changes in the tablets shape in few months. A comparison between the measured corrosion rates and the cave features showed that the values measured in the pools with stagnant water are too low to account for the largest solutional cave development, while the average values measured in the zones with moving water are compatible with the dimension of the cave rooms in the main cave levels, that must have developed when the base level was stable and hydrologic conditions favored the increase of water aggressivity.

Sources of Matter and Ore-Producing Fluid of the Tamunyer Gold-Sulfide Deposit (Northern Urals): Isotope Results

Science.gov (United States)

Zamyatina, D. A.; Murzin, V. V.

2018-02-01

The Tamunyer deposit is a typical example of gold-sulfide mineralization located in the lower lithologic-stratigraphic unit (S2-D1) of the Auerbach volcanic-plutonic belt. The latter comprises island-arc andesitic volcano-sediments, volcanics, and comagmatic intrusive formations. Carbonates have demonstrated intermediate values of δ13C between marine limestone and mantle. The quartz δ18O is in the range of 15.3-17.2‰. The δ34S of sulfides from the beresitized volcano-sedimentary rocks and ores varies widely from -7.5 to 12‰. The calculated isotope compositions of H2O, CO2, and H2S of the ore-bearing fluid imply two major sources of matter contributing to ore genesis: local rocks and foreign fluid. The ore-bearing fluid was formed by interaction and isotope equilibration between a deep magmatic fluid and marine carbonates (W/R 1), with the contribution of sulfur from the volcano-sedimentary rocks.

Hydrotreatment of heavy oil from coal liquefaction on Sulfide Ni - W Catalysts

International Nuclear Information System (INIS)

Zhi-ping Lei; Li-juan Gao; Heng-fu Shui; Shi-biao, Ren; Zhi-cai Wang; Kang-shi Gang

2011-01-01

Heavy oil (distillation temperature: 320-340 deg C) derived from the direct coal liquefaction process using Shengli coal were hydrotreated using sulfided Ni-Mo/Al 2 O 3 , Ni-W/Al 2 O 3 , and Ni-W/SiO 2 catalysts respectively. The sulfided catalysts were characterized by BET, XRD, H 2 -TPR and NH 3 -TPD respectively. The evaluations of the hydrodenitrogenation (HDN) and hydrodearomatization (HDA) properties of heavy oil on the three catalysts were carried out at 400 deg C and 5.0 MPa initial H2 pressure. The W-based catalysts displayed better performances than Mo-based catalysts for the HDN and HDA reactions. Al 2 O 3 supported catalysts were found to have higher catalytic activities than on SiO 2 supported ones. The activities of sulfided catalysts were associated mainly with the nature of active sites, acidity, metal sulfide crystallite size and the amount of the reducible sulfur species of metal sulfide. (author)

Thermal decomposition study of manganese sulfide (MnS) nanoparticles

Science.gov (United States)

Tailor, Jiten P.; Khimani, Ankurkumar J.; Chaki, Sunil H.; Deshpande, M. P.

2018-05-01

The as-synthesized manganese sulfide (MnS) nanoparticles were used for the thermal study. The nanoparticles were synthesized by simple wet chemical route at ambient temperature. The photoelectron binding energy and chemical composition of MnS nanoparticles was analyzed by X-ray photoelectron spectroscopy (XPS). The thermogravimetric (TG), differential thermogravimetric (DTG) and differential thermal analysis (DTA) were carried out on the as-synthesized MnS nanoparticles. The thermocurves were recorded in inert N2 atmosphere in the temperature range of ambient to 1173 K. The heating rates employed were 5, 10, 15 and 20 K/min. The thermodynamic parameters like activation energy (Ea), enthalpy change (ΔH), entropy change (ΔS) and change in Gibbs free energy (ΔG) of as-synthesized MnS nanoparticles were determined using Kissinger method. The obtained XPS and thermal results are discussed.

The selenium isotopic variations in chondrites are mass-dependent; Implications for sulfide formation in the early solar system

Science.gov (United States)

Labidi, J.; König, S.; Kurzawa, T.; Yierpan, A.; Schoenberg, R.

2018-01-01

Element transfer from the solar nebular gas to solids occurred either through direct condensation or via heterogeneous reactions between gaseous molecules and previously condensed solid matter. The precursors of altered sulfides observed in chondrites are for example attributed to reactions between gaseous hydrogen sulfide and metallic iron grains. The transfer of selenium to solids likely occurred through a similar pathway, allowing the formation of iron selenides concomitantly with sulfides. The formation rate of sulfide however remains difficult to assess. Here we investigate whether the Se isotopic composition of meteorites contributes to constrain sulfide formation during condensation stages of our solar system. We present high precision Se concentration and δ 82 / 78 Se data for 23 chondrites as well as the first δ 74 / 78 Se , δ 76 / 78 Se and δ 77 / 78 Se data for a sub-set of seven chondrites. We combine our dataset with previously published sulfur isotopic data and discuss aspects of sulfide formation for various types of chondrites. Our Se concentration data are within uncertainty to literature values and are consistent with sulfides being the dominant selenium host in chondrites. Our overall average δ 82 / 78 Se value for chondrites is - 0.21 ± 0.43 ‰ (n = 23, 2 s.d.), or - 0.14 ± 0.21 ‰ after exclusion of three weathered chondrites (n = 20, 2 s.d.). These average values are within uncertainty indistinguishable from a previously published estimate. For the first time however, we resolve distinct δ 82 / 78 Se between ordinary (- 0.14 ± 0.07 ‰, n = 9, 2 s.d.), enstatite (- 0.27 ± 0.05 ‰, n = 3, 2 s.d.) and CI carbonaceous chondrites (- 0.01 ± 0.06 ‰, n = 2, 2 s.d.). We also resolve a Se isotopic variability among CM carbonaceous chondrites. In addition, we report on δ 74 / 78 Se , δ 76 / 78 Se and δ 77 / 78 Se values determined for 7 chondrites. Our data allow evaluating the mass dependency of the δ 82 / 78 Se variations. Mass

A study on the mechanism of stress corrosion cracking of duplex stainless steels in hot alkaline-sulfide solution

Science.gov (United States)

Chasse, Kevin Robert

Duplex stainless steels (DSS) generally have superior strength and corrosion resistance as compared to most standard austenitic and ferritic stainless grades owing to a balanced microstructure of austenite and ferrite. As a result of having favorable properties, DSS have been selected for the construction of equipment in pulp and paper, chemical processing, nuclear, oil and gas as well as other industries. The use of DSS has been restricted in some cases because of stress corrosion cracking (SCC), which can initiate and grow in either the ferrite or austenite phase depending on the environment. Thorough understanding of SCC mechanisms of DSS in chloride- and hydrogen sulfide-containing solutions has been useful for material selection in many environments. However, understanding of SCC mechanisms of DSS in sulfide-containing caustic solutions is limited, which has restricted the capacity to optimize process and equipment design in pulp and paper environments. Process environments may contain different concentrations of hydroxide, sulfide, and chloride, altering corrosion and SCC susceptibility of each phase. Crack initiation and growth behavior will also change depending on the relative phase distribution and properties of austenite and ferrite. The role of microstructure and environment on the SCC of standard grade UNS S32205 and lean grade UNS S32101 in hot alkaline-sulfide solution were evaluated in this work using electrochemical, film characterization, mechanical testing, X-ray diffraction, and microscopy techniques. Microstructural aspects, which included residual stress state, phase distribution, phase ratio, and microhardness, were related to the propensity for SCC crack initiation in different simulated alkaline pulping liquors at 170 °C. Other grades of DSS and reference austenitic and superferritic grades of stainless steel were studied using exposure coupons for comparison to understand compositional effects and individual phase susceptibility

Determination of the compositions of the DIGM zone in nanocrystalline Ag/Au and Ag/Pd thin films by secondary neutral mass spectrometry

Directory of Open Access Journals (Sweden)

Gábor Y. Molnár

2016-03-01

Full Text Available Alloying by grain boundary diffusion-induced grain boundary migration is investigated by secondary neutral mass spectrometry depth profiling in Ag/Au and Ag/Pd nanocrystalline thin film systems. It is shown that the compositions in zones left behind the moving boundaries can be determined by this technique if the process takes place at low temperatures where solely the grain boundary transport is the contributing mechanism and the gain size is less than the half of the grain boundary migration distance. The results in Ag/Au system are in good accordance with the predictions given by the step mechanism of grain boundary migration, i.e., the saturation compositions are higher in the slower component (i.e., in Au or Pd. It is shown that the homogenization process stops after reaching the saturation values and further intermixing can take place only if fresh samples with initial compositions, according to the saturation values, are produced and heat treated at the same temperature. The reversal of the film sequence resulted in the reversal of the inequality of the compositions in the alloyed zones, which is in contrast to the above theoretical model, and explained by possible effects of the stress gradients developed by the diffusion processes itself.

Crossett Hydrogen Sulfide Air Sampling Report

Science.gov (United States)

This report summarizes the results of the EPA’s hydrogen sulfide air monitoring conducted along Georgia Pacific’s wastewater treatment system and in surrounding Crossett, AR, neighborhoods in 2017.

Geologic setting, sedimentary architecture, and paragenesis of the Mesoproterozoic sediment-hosted Sheep Creek Cu-Co-Ag deposit, Helena embayment, Montana

Science.gov (United States)

Graham, Garth; Hitzman, Murray W.; Zieg, Jerry

2012-01-01

The northern margin of the Helena Embayment contains extensive syngenetic to diagenetic massive pyrite horizons that extend over 25 km along the Volcano Valley-Buttress fault zone and extend up to 8 km basinward (south) within the Mesoproterozoic Newland Formation. The Sheep Creek Cu-Co deposit occurs within a structural block along a bend in the fault system, where replacement-style chalcopyrite mineralization is spatially associated mostly with the two stratigraphically lowest massive pyrite zones. These mineralized pyritic horizons are intercalated with debris flows derived from synsedimentary movement along the Volcano Valley-Buttress fault zone. Cominco American Inc. delineated a geologic resource of 4.5 Mt at 2.5% Cu and 0.1% Co in the upper sulfide zone and 4 Mt at 4% Cu within the lower sulfide zone. More recently, Tintina Resources Inc. has delineated an inferred resource of 8.48 Mt at 2.96% Cu, 0.12% Co, and 16.4 g/t Ag in the upper sulfide zone. The more intact upper sulfide zone displays significant thickness variations along strike thought to represent formation in at least three separate subbasins. The largest accumulation of mineralized sulfide in the upper zone occurs as an N-S–trending body that thickens southward from the generally E trending Volcano Valley Fault and probably occupies a paleograben controlled by normal faults in the hanging wall of the Volcano Valley Fault. Early microcrystalline to framboidal pyrite was accompanied by abundant and local barite deposition in the upper and lower sulfide zones, respectively. The sulfide bodies underwent intense (lower sulfide zone) to localized (upper sulfide zone) recrystallization and overprinting by coarser-grained pyrite and minor marcasite that is intergrown with and replaces dolomite. Silicification and paragenetically late chalcopyrite, along with minor tennantite in the upper sulfide zone, replaces fine-grained pyrite, barite, and carbonate. The restriction of chalcopyrite to inferred

Komatiites and nickel sulfide ores of the Black Swan area, Yilgarn Craton, Western Australia. 3: Komatiite geochemistry, and implications for ore forming processes

Science.gov (United States)

Barnes, Stephen J.; Hill, Robin E. T.; Evans, Noreen J.

2004-11-01

The Black Swan komatiite sequence is a package of dominantly olivine-rich cumulates with lesser volumes of spinifex textured rocks, interpreted as a section through an extensive komatiite lava flow field. The sequence hosts a number of nickel sulfide orebodies, including the Silver Swan massive shoot and the Cygnet and Black Swan disseminated orebodies. A large body of whole rock analyses on komatiitic rocks from the Black Swan area has been filtered for metasomatic effects. With the exception of mobile elements such as Ca and alkalis, most samples retain residual igneous geochemistry, and can be modelled predominantly by fractionation and accumulation of olivine. Whole rock MgO FeO relationships imply a relatively restricted range of olivine compositions, more primitive than the olivine which would have been in equilibrium with the transporting komatiite lavas, and together with textural data indicate that much of the cumulus olivine in the sequence was transported. Flow top compositions show evidence for chromite saturation, but the cumulates are deficient in accumulated chromite. Chromite compositions are typical of those found in compound flow-facies komatiites, and are distinct from those in komatiitic dunite bodies. Incompatible trace element abundances show three superimposed influences: control by the relative proportion of olivine to liquid; a signature of crustal contamination and an overprint of metasomatic introduction of LREE, Zr and Th. This overprint is most evident in cumulates, and relatively insignificant in the spinifex rocks. Platinum and palladium behaved as incompatible elements and are negatively correlated with MgO. They show no evidence for wholesale depletion due to sulfide extraction, which was evidently restricted to specific lava tubes or pathways. The lack of correspondence between PGE depletion and contamination by siliceous material implies that contamination alone is insufficient to generate S-saturation and ore formation in the

Sulfidation treatment of copper-containing plating sludge towards copper resource recovery.

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Kuchar, D; Fukuta, T; Onyango, M S; Matsuda, H

2006-11-02

The present study is concerned with the sulfidation treatment of copper-containing plating sludge towards copper resource recovery by flotation of copper sulfide from treated sludge. The sulfidation treatment was carried out by contacting simulated or real copper plating sludge with Na(2)S solution for a period of 5 min to 24 h. The initial molar ratio of S(2-) to Cu(2+) (S(2-) to Me(2+) in the case of real sludge) was adjusted to 1.00, 1.25 or 1.50, while the solid to liquid ratio was set at 1:50. As a result, it was found that copper compounds were converted to various copper sulfides within the first 5 min. In the case of simulated copper sludge, CuS was identified as the main sulfidation product at the molar ratio of S(2-) to Cu(2+) of 1.00, while Cu(7)S(4) (Roxbyite) was mainly found at the molar ratios of S(2-) to Cu(2+) of 1.50 and 1.25. Based on the measurements of oxidation-reduction potential, the formation of either CuS or Cu(7)S(4) at different S(2-) to Cu(2+) molar ratios was attributed to the changes in the oxidation-reduction potential. By contrast, in the case of sulfidation treatment of real copper sludge, CuS was predominantly formed, irrespective of S(2-) to Me(2+) molar ratio.

Novel Composite Hydrogen-Permeable Membranes for Nonthermal Plasma Reactors for the Decomposition of Hydrogen Sulfide

Energy Technology Data Exchange (ETDEWEB)

Morris Argyle; John Ackerman; Suresh Muknahallipatna; Jerry Hamann; Stanislaw Legowski; Gui-Bing Zhao; Sanil John; Ji-Jun Zhang; Linna Wang

2007-09-30

The goal of this experimental project was to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (H{sub 2}S) in a nonthermal plasma and to recover hydrogen (H{sub 2}) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys), but it was not achieved at the moderate pressure conditions used in this study. However, H{sub 2}S was successfully decomposed at energy efficiencies higher than any other reports for the high H{sub 2}S concentration and moderate pressures (corresponding to high reactor throughputs) used in this study.

Energy metabolism and metabolomics response of Pacific white shrimp Litopenaeus vannamei to sulfide toxicity.

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Li, Tongyu; Li, Erchao; Suo, Yantong; Xu, Zhixin; Jia, Yongyi; Qin, Jian G; Chen, Liqiao; Gu, Zhimin

2017-02-01

The toxicity and poisoning mechanisms of sulfide were studied in Litopenaeus vannamei from the perspective of energy metabolism and metabolomics. The lethal concentrations of sulfide in L. vannamei (LC50) at 24h, 48h, 72h, and 96h were determined. Sulfide at a concentration of 0, 1/10 (425.5μg/L), and 1/5 (851μg/L) of the LC 50 at 96h was used to test the metabolic responses of L. vannamei for 21days. The chronic exposure of shrimp to a higher sulfide concentration of 851μg/L decreased shrimp survival but did not affect weight gain or the hepatopancreas index. The glycogen content in the hepatopancreas and muscle and the activity of hepatopancreas cytochrome C oxidase of the shrimp exposed to all sulfide concentrations were significantly lower, and the serum glucose and lactic acid levels and lactic acid dehydrogenase activity were significantly lower than those in the control. Metabolomics assays showed that shrimp exposed to sulfide had lower amounts of serum pyruvic acid, succinic acid, glycine, alanine, and proline in the 425.5μg/L group and phosphate, succinic acid, beta-alanine, serine, and l-histidine in the 851μg/L group than in the control. Chronic sulfide exposure could disturb protein synthesis in shrimp but enhance gluconeogenesis and substrate absorption for ATP synthesis and tricarboxylic acid cycles to provide extra energy to cope with sulfide stress. Chronic sulfide exposure could adversely affect the health status of L. vannamei, as indicated by the high amounts of serum n-ethylmaleamic acid, pyroglutamic acid, aspartic acid and phenylalanine relative to the control. This study indicates that chronic exposure of shrimp to sulfide can decrease health and lower survival through functional changes in gluconeogenesis, protein synthesis and energy metabolism. Copyright © 2016 Elsevier B.V. All rights reserved.

Hydrogen sulfide production and volatilization in a polymictic eutrophic saline lake, Salton Sea, California.

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Reese, Brandi Kiel; Anderson, Michael A; Amrhein, Christopher

2008-11-15

The Salton Sea is a large shallow saline lake located in southern California that is noted for high sulfate concentrations, substantial algal productivity, and very warm water column temperatures. These conditions are well-suited for sulfide production, and sulfide has been implicated in summer fish kills, although no studies have been conducted to specifically understand hydrogen sulfide production and volatilization there. Despite polymictic mixing patterns and relatively short accumulation periods, the amount of sulfide produced is comparable to meromictic lakes. Sulfide levels in the Salton Sea reached concentrations of 1.2 mmol L(-1) of total free sulfide in the hypolimnion and 5.6 mmol L(-1) in the sediment pore water. Strong winds in late July mixed H2S into the surface water, where it depleted the entire water column of dissolved oxygen and reached a concentration of 0.1 mmol L(-1). Sulfide concentrations exceeded the toxicity threshold of tilapia (Oreochromis mossambicus) and combined with strong anoxia throughout the water column, resulted in a massive fish kill. The mixing of sulfide into the surface waters also increased atmospheric H2S concentrations, reaching 1.0 micromol m(-3). The flux of sulfide from the sediment into the water column was estimated to range from 2-3 mmol m(-2) day(-1) during the winter and up to 8 mmol m(-2) day(-1) during the summer. Application of the two-layer model for volatilization indicates that up to 19 mmol m(-2) day(-1) volatilized from the surface during the mixing event. We estimate that as much as 3400 Mg year(-1) or approximately 26% of sulfide that diffused into the water column from the deepest sediments may have been volatilized to the atmosphere.

Interaction distances in oxides, sulfides and selenides with face-centered packing

International Nuclear Information System (INIS)

Kesler, Ya.A.

1993-01-01

Concept of characteristic distances (CD) was specified with account of the principle of topologically face-centered anion packing: calculation method was presented and boundary conditions of CD concept applicability were considered. Tables of CD in oxides, sulfides and selenides, obtained in result of self-consistent calculations on the basis of experimental crystallographic data, are presented. Pair correlations between CD in oxides, sulfides and selenides were considered, their relationship with cation electron structure was established. Peculiarities of chemical bond in oxides, sulfides and selenides with face-centered anion packing were discussed

A kuroko-type polymetallic sulfide deposit in a submarine silicic caldera

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Iizasa; Fiske; Ishizuka; Yuasa; Hashimoto; Ishibashi; Naka; Horii; Fujiwara; Imai; Koyama

1999-02-12

Manned submersible studies have delineated a large and actively growing Kuroko-type volcanogenic massive sulfide deposit 400 kilometers south of Tokyo in Myojin Knoll submarine caldera. The sulfide body is located on the caldera floor at a depth of 1210 to 1360 meters, has an area of 400 by 400 by 30 meters, and is notably rich in gold and silver. The discovery of a large Kuroko-type polymetallic sulfide deposit in this arc-front caldera raises the possibility that the numerous unexplored submarine silicic calderas elsewhere might have similar deposits.

'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

Fluid Inclusion Study of The Tumpangpitu High Sulfidation Epithermal Gold Deposit in Banyuwangi District, East Java, Indonesia

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Yu Yu Myaing

2018-03-01

Full Text Available The Tumpangpitu high sulfidation (HS epithermal gold deposit is located in the south coast of East Java, Banyuwangi District, East Java Province, Indonesia. This area lies within the central portion of the Cenozoic Sunda‐Banda magmatic arc which trends southeast from northern Sumatra to west Java then eastward through east Java, Bali, Lombok, Sumbawa and terminating at Banda sea. The geology of the Tumpangpitu is predominantly occupied by Late Oligocene to Middle Miocene low-K calc-alkaline to alkaline andesitic volcanic rocks and interbedded with volcaniclastic rock sequences, which are associated with low-K intermediate intrusions. The mineralization style at the Tumpangpitu area is composed of a high‐sulfidation (HS epithermal gold-copper system which is typically associated with concealed gold-rich porphyry copper system. The HS epithermal mineralization is hosted by volcanic and volcaniclastic rocks in this research area. The mineralization domains are divided into Zone A, Zone B and Zone C which are situated along NW-SE-trending silica ledges zones. The HS epithermal mineralization is texturally occurs as vuggy replacements mineralization as well as stockworks, disseminated forms, fractures and veins. Fluid inclusion study was conducted for 6 quartz vein samples which petrographically entrapped fluid inclusions. Homogenization temperature (Th and melting temperature (Tm can microthermometrically be determined by fluid inclusion analysis. The average homogenization temperature (Th of the fluid inclusions gives 180˚C to 342˚C and melting temperature are from -0.1 ˚C to -1.4˚C. Tm corresponds to the salinities ranging from 0.1 to 4.5 wt% NaCl equivalent. The paleodepth of ore formation can be estimated from the salinity of fluid. Since the deposit was not formed at boiling condition, the minimum paleodepth of ore (quartz samples taken from both shallow level (53.35 m and deep level (135.15 m is determined at 650m and 1,220 m

Metagenome of a Versatile Chemolithoautotroph from Expanding Oceanic Dead Zones

Energy Technology Data Exchange (ETDEWEB)

Walsh, David A.; Zaikova, Elena; Howes, Charles L.; Song, Young; Wright, Jody; Tringe, Susannah G.; Tortell, Philippe D.; Hallam, Steven J.

2009-07-15

Oxygen minimum zones (OMZs), also known as oceanic"dead zones", are widespread oceanographic features currently expanding due to global warming and coastal eutrophication. Although inhospitable to metazoan life, OMZs support a thriving but cryptic microbiota whose combined metabolic activity is intimately connected to nutrient and trace gas cycling within the global ocean. Here we report time-resolved metagenomic analyses of a ubiquitous and abundant but uncultivated OMZ microbe (SUP05) closely related to chemoautotrophic gill symbionts of deep-sea clams and mussels. The SUP05 metagenome harbors a versatile repertoire of genes mediating autotrophic carbon assimilation, sulfur-oxidation and nitrate respiration responsive to a wide range of water column redox states. Thus, SUP05 plays integral roles in shaping nutrient and energy flow within oxygen-deficient oceanic waters via carbon sequestration, sulfide detoxification and biological nitrogen loss with important implications for marine productivity and atmospheric greenhouse control.

Low temperature geomicrobiology follows host rock composition along a geochemical gradient in Lau Basin

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Jason B Sylvan

2013-03-01

Full Text Available The East Lau Spreading Center (ELSC and Valu Fa Ridge (VFR comprise a ridge segment in the southwest Pacific Ocean where rapid transitions in the underlying mantle chemistry manifest themselves as gradients in seafloor rock geochemistry. We studied the geology and microbial diversity of three silicate rock samples and three inactive sulfide chimney samples collected, from north to south, at the vent fields Kilo Moana, ABE, Tui Malila and Mariner. This is the first study of microbial populations on basaltic andesite, which was sampled at Mariner vent field. Silicate rock geochemistry exhibits clear latitudinal trends that are mirrored by changes in bacterial community composition. α-proteobacteria, ε-proteobacteria and Bacteroidetes are most common on a silicate collected from Kilo Moana and their proportions decrease linearly on silicates collected further south. Conversely, a silicate from Mariner vent field hosts high proportions of a unique lineage of Chloroflexi unrelated (<90% sequence similarity to previously recovered environmental clones or isolates, which decrease at ABE and are absent at Kilo Moana. The exteriors of inactive sulfide structures are dominated by lineages of sulfur oxidizing α-proteobacteria, γ-proteobacteria and ε-proteobacteria while the interior of one chimney is dominated by putative sulfur-reducing δ-proteobacteria. A comparison of bacterial communities on inactive sulfides from this and previous studies reveals the presence of a clade of uncultured Bacteroidetes exclusive to sulfidic environments, and a high degree of heterogeneity in bacterial community composition from one sulfide structure to another. In light of the heterogeneous nature of bacterial communities observed here and in previous studies of both active and inactive hydrothermal sulfide structures, the presence of numerous niches may be detected on these structures in the future by finer scale sampling and analysis.

The timing of compositionally-zoned magma reservoirs and mafic 'priming' weeks before the 1912 Novarupta-Katmai rhyolite eruption

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Singer, Brad S.; Costa, Fidel; Herrin, Jason S.; Hildreth, Wes; Fierstein, Judith

2016-01-01

The June 6, 1912 eruption of more than 13 km3 of dense rock equivalent (DRE) magma at Novarupta vent, Alaska was the largest of the 20th century. It ejected >7 km3 of rhyolite, ~1.3 km3 of andesite and ~4.6 km3 of dacite. Early ideas about the origin of pyroclastic flows and magmatic differentiation (e.g., compositional zonation of reservoirs) were shaped by this eruption. Despite being well studied, the timing of events that led to the chemically and mineralogically zoned magma reservoir remain poorly known. Here we provide new insights using the textures and chemical compositions of plagioclase and orthopyroxene crystals and by reevaluating previous U-Th isotope data. Compositional zoning of the magma reservoir likely developed a few thousand years before the eruption by several additions of mafic magma below an extant silicic reservoir. Melt compositions calculated from Sr contents in plagioclase fill the compositional gap between 68 and 76% SiO2 in whole pumice clasts, consistent with uninterrupted crystal growth from a continuum of liquids. Thus, our findings support a general model in which large volumes of crystal-poor rhyolite are related to intermediate magmas through gradual separation of melt from crystal-rich mush. The rhyolite is incubated by, but not mixed with, episodic recharge pulses of mafic magma that interact thermochemically with the mush and intermediate magmas. Hot, Mg-, Ca-, and Al-rich mafic magma intruded into, and mixed with, deeper parts of the reservoir (andesite and dacite) multiple times. Modeling the relaxation of the Fe-Mg concentrations in orthopyroxene and Mg in plagioclase rims indicates that the final recharge event occurred just weeks prior to the eruption. Rapid addition of mass, volatiles, and heat from the recharge magma, perhaps aided by partial melting of cumulate mush below the andesite and dacite, pressurized the reservoir and likely propelled a ~10 km lateral dike that allowed the overlying rhyolite to reach the surface.

Oxygen isotope zonation at the Golden Cross low-sulfidation epithermal gold deposit, New Zealand

International Nuclear Information System (INIS)

Mauk, J.L.; Simpson, M.P.

2001-01-01

Forty-one whole rock samples from the Gold Cross low-sulfidation epithermal Au-Ag deposit have δ 18 O values that range from 4.4 to 9.3 per mil, with an average value of 7.0 per mil. Unaltered and weakly altered rocks have δ 18 O values greater than 8 per mil, and the orebody is surrounded by samples that are depleted in 18 O. A strongly silicified sample adjacent to the Empire Vein System has a δ 18 O value of 9.0 per mil, similar to previously reported analyses of vein quartz (7.0 to 11.7 per mil, average 9.4 per mil). This suggests that, in detail, Golden Cross may have a zone of 18 O-enriched wall rocks in the core of the deposit, adjacent to the main underground veins. Although some workers have suggested that stable isotope geochemistry may provide useful information for epithermal mineral deposit exploration, at Golden Cross this is not the case. Alteration minerals, major elements and trace elements all define larger, less ambiguous halos than the zone of 18 O-depleted wall rocks. (author). 21 refs., 3 figs., 1 tab

Enhanced conductive loss in nickel–cobalt sulfide nanostructures for highly efficient microwave absorption and shielding

Science.gov (United States)

Li, Wanrong; Zhou, Min; Lu, Fei; Liu, Hongfei; Zhou, Yuxue; Zhu, Jun; Zeng, Xianghua

2018-06-01

Microwave-absorbing materials with light weight and high efficiency are desirable in addressing electromagnetic interference (EMI) problems. Herein, a nickel–cobalt sulfide (NCS) nanostructure was employed as a robust microwave absorber, which displayed an optimized reflection loss of  ‑49.1 dB in the gigahertz range with a loading of only 20 wt% in an NCS/paraffin wax composite. High electrical conductivity was found to contribute prominent conductive loss in NCS, leading to intense dielectric loss within a relatively low mass loading. Furthermore, owing to its high electrical conductivity and remarkable dielectric loss to microwaves, the prepared NCS exhibited excellent performance in EMI shielding. The EMI shielding efficiency of the 50 wt% NCS/paraffin composite exceeded 55 dB at the X-band, demonstrating NCS is a versatile candidate for solving EMI problems.

In Vitro Antiparasitic and Apoptotic Effects of Antimony Sulfide Nanoparticles on Leishmania infantum

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Saied Soflaei

2012-01-01

Full Text Available Visceral leishmaniasis is one of the most important sever diseases in tropical and subtropical countries. In the present study the effects of antimony sulfide nanoparticles on Leishmania infantum in vitro were evaluated. Antimony sulfide NPs (Sb2S5 were synthesized by biological method from Serratia marcescens bacteria. Then the cytotoxicity effects of different concentrations (5, 10, 25, 50, and 100 μg/mL of this nanoparticle were assessed on promastigote and amastigote stages of L. infantum. MTT method was used for verification results of promastigote assay. Finally, the percentages of apoptotic, necrotic, and viable cells were determined by flow cytometry. The results indicated the positive effectiveness of antimony sulfide NPs on proliferation of promastigote form. The IC50 (50% inhibitory concentration of antimony sulfide NPs on promastigotes was calculated 50 μg/mL. The cytotoxicity effect was dose-dependent means by increasing the concentration of antimony sulfide NPs, the cytotoxicity curve was raised and the viability curve of the parasite dropped simultaneously. Moreover, the IC50 of antimony sulfide NPs on amastigote stage was calculated 25 μg/mL. On the other hand, however, antimony sulfide NPs have a low cytotoxicity effect on uninfected macrophages but it can induce apoptosis in promastigote stage at 3 of 4 concentrations.

Vegetation successfully prevents oxidization of sulfide minerals in mine tailings.

Science.gov (United States)

Li, Yang; Sun, Qingye; Zhan, Jing; Yang, Yang; Wang, Dan

2016-07-15

The oxidization of metal sulfide in tailings causes acid mine drainage. However, it remains unclear whether vegetation prevents the oxidization of metal sulfides. The oxidization characteristics and microbial indices of the tailings in the presence of various plant species were investigated to explore the effects of vegetation on the oxidization of sulfide minerals in tailings. The pH, reducing sulfur, free iron oxides (Fed), chemical oxygen consumption (COC) and biological oxygen consumption (BOC) were measured. Key iron- and sulfur-oxidizing bacteria (Acidithiobacillus spp., Leptospirillum spp. and Thiobacillus spp.) were quantified using real-time PCR. The results indicate that vegetation growing on tailings can effectively prevent the oxidization of sulfide minerals in tailings. A higher pH and reducing-sulfur content and lower Fed were observed in the 0-30 cm depth interval in the presence of vegetation compared to bare tailings (BT). The COC gradually decreased with depth in all of the soil profiles; specifically, the COC rapidly decreased in the 10-20 cm interval in the presence of vegetation but gradually decreased in the BT profiles. Imperata cylindrica (IC) and Chrysopogon zizanoides (CZ) profiles contained the highest BOC in the 10-20 cm interval. The abundance of key iron- and sulfur-oxidizing bacteria in the vegetated tailings were significantly lower than in the BT; in particular, IC was associated with the lowest iron- and sulfur-oxidizing bacterial abundance. In conclusion, vegetation successfully prevented the oxidization of sulfide minerals in the tailings, and Imperata cylindrica is the most effective in reducing the number of iron- and sulfur-oxidizing bacteria and helped to prevent the oxidization of sulfide minerals in the long term. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

Tailings deposits generated from mining activities represent a potential risk for the aquatic environment through the release of potentially toxic metals and metalloids occurring in a variety of minerals present in the tailings. Physicochemical and mineralogical characteristics of tailings such as total concentrations of chemical elements, pH, ratio of acid-producing to acid-neutralizing minerals, and primary and secondary mineral phases are very important factors that control the actual release of potentially toxic metals and metalloids from the tailings to the environment. The aims of this study are the determination of geochemical and mineralogical characteristics of tailings deposited in voluminous impoundment situated near the village of Markušovce (eastern Slovakia) and identification of the processes controlling the mobility of selected toxic metals (Cu, Hg) and metalloids (As, Sb). The studied tailings have unique features in comparison with the other tailings investigated previously because of the specific mineral assemblage primarily consisting of barite, siderite, quartz, and minor sulfides. To meet the aims, samples of the tailings were collected from 3 boreholes and 15 excavated pits and subjected to bulk geochemical analyses (i.e., determination of chemical composition, pH, Eh, acid generation, and neutralization potentials) combined with detailed mineralogical characterization using optical microscopy, X-ray diffraction (XRD), electron microprobe analysis (EMPA), and micro-X-ray diffraction (μ-XRD). Additionally, the geochemical and mineralogical factors controlling the transfer of potentially toxic elements from tailings to waters were also determined using short-term batch test (European norm EN 12457), sampling of drainage waters and speciation-equilibrium calculations performed with PHREEQC. The tailings mineral assemblage consists of siderite, barite, quartz, and dolomite. Sulfide minerals constitute only a minor proportion of the tailings

Influence of sulfide concentration on the corrosion behavior of pure copper in synthetic seawater

International Nuclear Information System (INIS)

Taniguchi, Naoki; Kawasaki, Manabu

2008-01-01

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 2 S. 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

Apatite in carbonatitic rocks: Compositional variation, zoning, element partitioning and petrogenetic significance

Science.gov (United States)

Chakhmouradian, Anton R.; Reguir, Ekaterina P.; Zaitsev, Anatoly N.; Couëslan, Christopher; Xu, Cheng; Kynický, Jindřich; Mumin, A. Hamid; Yang, Panseok

2017-03-01

Apatite-group phosphates are nearly ubiquitous in carbonatites, but our understanding of these minerals is inadequate, particularly in the areas of element partitioning and petrogenetic interpretation of their compositional variation among spatially associated rocks and within individual crystals. In the present work, the mode of occurrence, and major- and trace-element chemistry of apatite (sensu lato) from calcite and dolomite carbonatites, their associated cumulate rocks (including phoscorites) and hydrothermal parageneses were studied using a set of 80 samples from 50 localities worldwide. The majority of this set represents material for which no analytical data are available in the literature. Electron-microprobe and laser-ablation mass-spectrometry data ( 600 and 400 analyses, respectively), accompanied by back-scattered-electron and cathodoluminescence images and Raman spectra, were used to identify the key compositional characteristics and zoning patterns of carbonatitic apatite. These data are placed in the context of phosphorus geochemistry in carbonatitic systems and carbonatite evolution, and compared to the models proposed by previous workers. The documented variations in apatite morphology and zoning represent a detailed record of a wide range of evolutionary processes, both magmatic and fluid-driven. The majority of igneous apatite from the examined rocks is Cl-poor fluorapatite or F-rich hydroxylapatite (≥ 0.3 apfu F) with 0.2-2.7 wt.% SrO, 0-4.5 wt.% LREE2O3, 0-0.8 wt.% Na2O, and low levels of other cations accommodated in the Ca site (up to 1000 ppm Mn, 2300 ppm Fe, 200 ppm Ba, 150 ppm Pb, 700 ppm Th and 150 ppm U), none of which show meaningful correlation with the host-rock type. Silicate, (SO4)2 - and (VO4)3 - anions, substituting for (PO4)3 -, tend to occur in greater abundance in crystals from calcite carbonatites (up to 4.2 wt.% SiO2, 1.5 wt.% SO3 and 660 ppm V). Although (CO3)2 - groups are very likely present in some samples, Raman micro

Hydrogeology of northern Sierra de Chiapas, Mexico: a conceptual model based on a geochemical characterization of sulfide-rich karst brackish springs

Science.gov (United States)

Rosales Lagarde, Laura; Boston, Penelope J.; Campbell, Andrew R.; Hose, Louise D.; Axen, Gary; Stafford, Kevin W.

2014-09-01

Conspicuous sulfide-rich karst springs flow from Cretaceous carbonates in northern Sierra de Chiapas, Mexico. This is a geologically complex, tropical karst area. The physical, geologic, hydrologic and chemical attributes of these springs were determined and integrated into a conceptual hydrogeologic model. A meteoric source and a recharge elevation below 1,500 m are estimated from the spring-water isotopic signature regardless of their chemical composition. Brackish spring water flows at a maximum depth of 2,000 m, as inferred from similar chemical attributes to the produced water from a nearby oil well. Oil reservoirs may be found at depths below 2,000 m. Three subsurface environments or aquifers are identified based on the B, Li+, K+ and SiO2 concentrations, spring water temperatures, and CO2 pressures. There is mixing between these aquifers. The aquifer designated Local is shallow and contains potable water vulnerable to pollution. The aquifer named Northern receives some brackish produced water. The composition of the Southern aquifer is influenced by halite dissolution enhanced at fault detachment surfaces. Epigenic speleogenesis is associated with the Local springs. In contrast, hypogenic speleogenesis is associated with the brackish sulfidic springs from the Northern and the Southern environments.

Ionic liquid-modified metal sulfides/graphene oxide nanocomposites for photoelectric conversion

International Nuclear Information System (INIS)

Zhang, Yu; Zhang, Yù; Pei, Qi; Feng, Ting; Mao, Hui; Zhang, Wei; Wu, Shuyao; Liu, Daliang; Wang, Hongyu; Song, Xi-Ming

2015-01-01

Graphical abstract: - Highlights: • Metal sulfide (CdS, ZnS, Ag 2 S)/GO nanocomposites were prepared by electrostatic adherence. • Ionic liquid was used to link the metal sulfide and GO in the electrostatic adherence process. • The as-prepared samples showed enhanced photocurrent and highly efficient photocatalytic activity under visible light irradiation. - Abstract: Ionic liquid-modified metal sulfides/graphene oxide nanocomposites are prepared via a facile electrostatic adsorption. Ionic liquid (IL) is firstly used as surface modifier and structure-directing agent of metal sulfide (MS) crystallization process, obtaining ionic liquid modified-MS (IL-MS) nanoparticles with positive charges on surface. IL-MS/GO is obtained by electrostatic adherence between positively charged IL-MS and negatively charged graphene oxide (GO). The as-prepared sample shows enhanced photocurrent and highly efficient photocatalytic activity under visible light irradiation, indicating IL-MS/GO nanocomposites greatly promoted the separation of photogenerated electron–hole pairs

Sulfur concentration at sulfide saturation (SCSS) in magmatic silicate melts

Science.gov (United States)

Liu, Yanan; Samaha, Naji-Tom; Baker, Don R.

2007-04-01

The sulfur concentration in silicate melts at sulfide saturation (SCSS) was experimentally investigated in a temperature range from 1150 to 1450 °C and a pressure range from 500 MPa to 1 GPa in a piston-cylinder apparatus. The investigated melt compositions varied from rhyolitic to basaltic and water concentrations varied from 0 to ˜9 wt%. All experiments were saturated with FeS melt or pyrrhotite crystals. Temperature was confirmed to have a positive effect on the SCSS. Experimental oxygen fugacities were either near the carbon-carbon monoxide buffer or one log unit above the nickel-nickel oxide buffer, and found to positively affect the SCSS. Combining our results with data from the literature we constructed a model to predict the SCSS in melts ranging in composition from komatiitic to rhyolitic, with water concentrations from 0 to 9 wt%, at pressures from 1 bar to 9 GPa and oxygen fugacities between ˜2 log units below the fayalite-magnetite-quartz buffer to ˜2 log units above it. The coefficients were obtained by multiple linear regression of experimental data and the best model found for the prediction of the SCSS is: ln(Sinppm)=11.35251-{4454.6}/{T}-0.03190{P}/{T}+0.71006ln(MFM)-1.98063[(MFM)(XO)]+0.21867ln(XO)+0.36192lnX where P is in bar, T is in K, MFM is a compositional parameter describing the melt based upon cation mole fractions: MFM={Na+K+2(Ca+Mg+Fe)}/{Si×(Al+Fe)}, XO is the mole fraction of water in the melt, and X is the mole fraction of FeO in the melt. This model was independently tested against experiments performed on anhydrous and hydrous melts in the temperature range from 800 to 1800 °C and 1-9 GPa. The model typically predicts the measured values of the natural log of the SCSS (in ppm) for komatiitic to rhyolitic (˜42 to ˜74 wt% SiO 2) melts to within 5% relative, but is less accurate for high-silica (>76 wt% SiO 2) rhyolites, especially those with molar ratios of iron to sulfur below 2. We demonstrate how this model can be used with

Temperature and composition of carbonate cements record early structural control on cementation in a nascent deformation band fault zone: Moab Fault, Utah, USA

Science.gov (United States)

Hodson, Keith R.; Crider, Juliet G.; Huntington, Katharine W.

2016-10-01

Fluid-driven cementation and diagenesis within fault zones can influence host rock permeability and rheology, affecting subsequent fluid migration and rock strength. However, there are few constraints on the feedbacks between diagenetic conditions and structural deformation. We investigate the cementation history of a fault-intersection zone on the Moab Fault, a well-studied fault system within the exhumed reservoir rocks of the Paradox Basin, Utah, USA. The fault zone hosts brittle structures recording different stages of deformation, including joints and two types of deformation bands. Using stable isotopes of carbon and oxygen, clumped isotope thermometry, and cathodoluminescence, we identify distinct source fluid compositions for the carbonate cements within the fault damage zone. Each source fluid is associated with different carbonate precipitation temperatures, luminescence characteristics, and styles of structural deformation. Luminescent carbonates appear to be derived from meteoric waters mixing with an organic-rich or magmatic carbon source. These cements have warm precipitation temperatures and are closely associated with jointing, capitalizing on increases in permeability associated with fracturing during faulting and subsequent exhumation. Earlier-formed non-luminescent carbonates have source fluid compositions similar to marine waters, low precipitation temperatures, and are closely associated with deformation bands. The deformation bands formed at shallow depths very early in the burial history, preconditioning the rock for fracturing and associated increases in permeability. Carbonate clumped isotope temperatures allow us to associate structural and diagenetic features with burial history, revealing that structural controls on fluid distribution are established early in the evolution of the host rock and fault zone, before the onset of major displacement.

Hydrotreatment of heavy oil from coal liquefaction on Sulfide Ni - W Catalysts

Energy Technology Data Exchange (ETDEWEB)

Zhi-ping Lei; Li-juan Gao; Heng-fu Shui; Shi-biao, Ren; Zhi-cai Wang; Kang-shi Gang, E-mail: shhf@ahut.edu.c [Anhui University of Technology, Maanshan (China). School of Chemistry and Chemical Engineering. Anhui Key Lab. of Coal Clean Conversion and Utilization

2011-07-01

Heavy oil (distillation temperature: 320-340 deg C) derived from the direct coal liquefaction process using Shengli coal were hydrotreated using sulfided Ni-Mo/Al{sub 2}O{sub 3}, Ni-W/Al{sub 2}O{sub 3}, and Ni-W/SiO{sub 2} catalysts respectively. The sulfided catalysts were characterized by BET, XRD, H{sub 2}-TPR and NH{sub 3}-TPD respectively. The evaluations of the hydrodenitrogenation (HDN) and hydrodearomatization (HDA) properties of heavy oil on the three catalysts were carried out at 400 deg C and 5.0 MPa initial H2 pressure. The W-based catalysts displayed better performances than Mo-based catalysts for the HDN and HDA reactions. Al{sub 2}O{sub 3} supported catalysts were found to have higher catalytic activities than on SiO{sub 2} supported ones. The activities of sulfided catalysts were associated mainly with the nature of active sites, acidity, metal sulfide crystallite size and the amount of the reducible sulfur species of metal sulfide. (author)

The thermodynamics of arsenates, selenites, and sulfates in the oxidation zone of sulfide ores. XI. Solubility of synthetic chalcomenite analog and zinc selenite at 25°C

Science.gov (United States)

Charykova, M. V.; Krivovichev, V. G.; Ivanova, N. M.; Semenova, V. V.

2015-12-01

The aim of this study is the synthesis of CuSeO3·2H2O (chalcomenite analog), ZnSeO3·2H2O, and ZnSeO3·H2O and the investigation of their solubility in water. CuSeO3·2H2O has been synthesized from solutions of Cu nitrate and Na selenite, while Zn selenites were synthesized from solutions of Zn nitrate and Na selenite. The samples obtained have been examined with X-ray diffraction and infrared and Raman spectroscopy. The solubility has been determined using the isothermal saturation method in ampoules at 25°C. The solubility has been calculated using the Geochemist's Workbench (GMB 9.0) software package. Solubility products have been calculated for CuSeO3·2H2O (10-10.63), ZnSeO3·2H2O (10-8.35), and ZnSeO3·H2O (10-7.96). The database used comprises thermodynamic characteristics of 46 elements, 47 base particles, 48 redox pairs, 551 particles in solution, and 624 solid phases. The Eh-pH diagrams of the Zn-Se-H2O and Cu-Se-H2O systems were plotted for the average contents of these elements in underground water in oxidation zones of sulfide deposits.

In situ electropolymerization of polyaniline/cobalt sulfide decorated carbon nanotube composite catalyst toward triiodide reduction in dye-sensitized solar cells

Science.gov (United States)

Xiao, Yaoming; Wang, Wei-Yan; Chou, Shu-Wei; Lin, Tsung-Wu; Lin, Jeng-Yu

2014-11-01

In this study, we report a composite film composed of the cobalt sulfide (CoS1.097) nanoclusters/multi-wall carbon nanotube nanocomposites (MWCNT@CoS1.097) embedded polyaniline (PANI) film (denoted as PANI/MWCNT@CoS1.097) by an in situ electropolymerization onto a fluorinated tin oxide (FTO) glass substrate as a counter electrode (CE) for Pt-free dye-sensitized solar cells (DSCs) for the first time. The extensive cyclic voltammograms (CVs) and electrochemical impedance measurements show the PANI/MWCNT@CoS1.097 CE with an enhanced electrocatalytic activity for I3- reduction compared to PANI and MWCNT@CoS1.097 CEs. Moreover, the peak current densities of the PANI/MWCNT@CoS1.097 CE show no sign of degradation after consecutive 200 CV tests, suggesting its great chemical and electrochemical stability. Furthermore, the DSC based on the in situ electropolymerized PANI/MWCNT@CoS1.097 CE achieves an improved photovoltaic conversion efficiency of 7.02%, which is higher than those of the DSCs with PANI CE (6.06%) and with MWCNT@CoS1.097 CE (5.54%), and is even comparable to that of the DSC using the Pt CE (7.16%). Therefore, the PANI/MWCNT@CoS1.097 CE can be regarded as a promising alternative CE for Pt-free DSCs.

Composition suitable as collection agent in ore flotation process and preparation of said composition

International Nuclear Information System (INIS)

Bresson, C.R.; Parlman, R.M.

1984-01-01

A composition and process are provided for the recovery of the values of zinc, molybdenum, copper, lead, ion (pyrite), and iron-containing small amounts of gold or uranium, or both, from ores comprising these mineral sulfides. The aqueous composition is the impure form of an alkali metal alkyl trithiocarbonate compound. The process comprises employing said aqueous composition as a collection agent for the above minerals in an ore recovery process. A process for the separation of zinc values from lead values from an ore comprising both is provided by employing an alkali metal alkyl trithiocarbonate compound as a collection agent for zinc. In addition, both a composition and process are provided for the recovery of the values of iron, copper, and lead from ores comprising these values. The composition consists essentially of a dispersant and an impure form of an alkali metal alkyl trithiocarbonate compound. The process comprises employing this composition as a collection agent for the above minerals in an ore recovery process

Biological nitrate transport in sediments on the Peruvian margin mitigates benthic sulfide emissions and drives pelagic N loss during stagnation events

Science.gov (United States)

Dale, A. W.; Sommer, S.; Lomnitz, U.; Bourbonnais, A.; Wallmann, K.

2016-06-01

Benthic N cycling in the Peruvian oxygen minimum zone (OMZ) was investigated at ten stations along 12 °S from the middle shelf (74 m) to the upper slope (1024 m) using in situ flux measurements, sediment biogeochemistry and modeling. Middle shelf sediments were covered by mats of the filamentous bacteria Thioploca spp. and contained a large 'hidden' pool of nitrate that was not detectable in the porewater. This was attributed to a biological nitrate reservoir stored within the bacteria to oxidize sulfide during 'dissimilatory nitrate reduction to ammonium' (DNRA). The extremely high rates of DNRA on the shelf (15.6 mmol m-2 d-1 of N), determined using an empirical steady-state model, could easily supply all the ammonium requirements for anammox in the water column. The model further showed that denitrification by foraminifera may account for 90% of N2 production at the lower edge of the OMZ. At the time of sampling, dissolved oxygen was below detection limit down to 400 m and the water body overlying the shelf had stagnated, resulting in complete depletion of nitrate and nitrite. A decrease in the biological nitrate pool was observed on the shelf during fieldwork concomitant with a rise in porewater sulfide levels in surface sediments to 2 mM. Using a non-steady state model to simulate this natural anoxia experiment, these observations were shown to be consistent with Thioploca surviving on a dwindling intracellular nitrate reservoir to survive the stagnation period. The model shows that sediments hosting Thioploca are able to maintain high ammonium fluxes for many weeks following stagnation, potentially sustaining pelagic N loss by anammox. In contrast, sulfide emissions remain low, reducing the economic risk to the Peruvian fishery by toxic sulfide plume development.

The sampling of hydrogen sulfide in air with impregnated filter paper

NARCIS (Netherlands)

Huygen, C.

1964-01-01

A method is proposed for the quantitative collection of hydrogen sulfide in air on impregnated filter paper. An aqueous solution of potassium hydroxide, potassium zincate and glycerol is used as impregnating fluid. The stability of the collected sulfide and the efficiency of collection at different

Evidence of molybdenum association with particulate organic matter under sulfidic conditions

DEFF Research Database (Denmark)

Dahl, Tais Wittchen; Chappaz, A.; Hoek, Joost

2017-01-01

, consisting of mainly Mo(IV)-sulfide compounds with molecular structures similar to Mo enzymes and to those found in natural euxinic sediments. Therefore, we propose that Mo removal in natural sulfidic waters can proceed via a non-Fe-assisted pathway that requires particulate organic matter (dead or living......The geochemical behavior of molybdenum (Mo) in the oceans is closely linked to the presence of sulfide species in anoxic environments, where Fe availability may play a key role in the Mo scavenging. Here, we show that Mo(VI) is reduced in the presence of particulate organic matter (represented...

Removal of highly elevated nitrate from drinking water by pH-heterogenized heterotrophic denitrification facilitated with ferrous sulfide-based autotrophic denitrification.

Science.gov (United States)

Huang, Bin; Chi, Guangyu; Chen, Xin; Shi, Yi

2011-11-01

The performance of acetic acid-supported pH-heterogenized heterotrophic denitrification (HD) facilitated with ferrous sulfide-based autotrophic denitrification (AD) was investigated in upflow activated carbon-packed column reactors for reliable removal of highly elevated nitrate (42 mg NO(3)-Nl(-1)) in drinking water. The use of acetic acid as substrate provided sufficient internal carbon dioxide to completely eliminate the need of external pH adjustment for HD, but simultaneously created vertically heterogenized pH varying from 4.8 to 7.8 in the HD reactor. After 5-week acclimation, the HD reactor developed a moderate nitrate removal capacity with about one third of nitrate removal occurring in the acidic zone (pH 4.8-6.2). To increase the treatment reliability, acetic acid-supported HD was operated under 10% carbon limitation to remove >85% of nitrate, and ferrous sulfide-based AD was supplementally operated to remove residual nitrate and formed nitrite without excess of soluble organic carbon, nitrite or sulfate in the final effluent. Copyright © 2011 Elsevier Ltd. All rights reserved.

Modeling and experimental investigation of induction welding of thermoplastic composites and comparison with other welding processes

NARCIS (Netherlands)

Gouin O'Shaughnessey, P.; Dube, M; Fernandez Villegas, I.

2016-01-01

A three-dimensional finite element model of the induction welding of carbon fiber/polyphenylene sulfide thermoplastic composites is developed. The model takes into account a stainless steel mesh heating element located at the interface of the two composite adherends to be welded. This heating

A Study on Dielectric Properties of Cadmium Sulfide-Zinc Sulfide Core-Shell Nanocomposites for Application as Nanoelectronic Filter Component in the Microwave Domain

Science.gov (United States)

Devi, Jutika; Datta, Pranayee

2018-03-01

Complex permittivities of cadmium sulfide (CdS), zinc sulfide (ZnS), and of cadmium sulfide-zinc sulfide (CdS/ZnS) core-shell nanoparticles embedded in a polyvinyl alcohol matrix (PVA) were measured in liquid phase using a VectorNetwork Analyzer in the frequency range of 500 MHz-10 GHz. These nanocomposites are modeled as an embedded capacitor, and their electric field distribution and polarization have been studied using COMSOL Multiphysics software. By varying the thickness of the shell and the number of inclusions, the capacitance values were estimated. It was observed that CdS, ZnS and CdS/ZnS core-shell nanoparticles embedded in a polyvinyl alcohol matrix show capacitive behavior. There is a strong influence of the dielectric properties in the capacitive behavior of the embedded nanocapacitor. The capping matrix, position and filling factors of nanoinclusions all affect the capacitive behavior of the tested nanocomposites. Application of the CdS, ZnS and CdS/ZnS core-shell nanocomposite as the passive low-pass filter circuit has also been investigated. From the present study, it has been found that CdS/ZnS core-shell nanoparticles embedded in PVA matrix are potential structures for application as nanoelectronic filter components in different areas of communication.

Development of a molecular dynamic based cohesive zone model for prediction of an equivalent material behavior for Al/Al2O3 composite

Energy Technology Data Exchange (ETDEWEB)

Sazgar, A. [Center of Excellence in Design, Robotics and Automation, Department of Mechanical Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Movahhedy, M.R., E-mail: movahhed@sharif.edu [Center of Excellence in Design, Robotics and Automation, Department of Mechanical Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Mahnama, M. [School of Mechanical Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Sohrabpour, S. [Center of Excellence in Design, Robotics and Automation, Department of Mechanical Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of)

2017-01-02

The interfacial behavior of composites is often simulated using a cohesive zone model (CZM). In this approach, a traction-separation (T-S) relation between the matrix and reinforcement particles, which is often obtained from experimental results, is employed. However, since the determination of this relation from experimental results is difficult, the molecular dynamics (MD) simulation may be used as a virtual environment to obtain this relation. In this study, MD simulations under the normal and shear loadings are used to obtain the interface behavior of Al/Al2O3 composite material and to derive the T-S relation. For better agreement with Al/Al2O3 interfacial behavior, the exponential form of the T-S relation suggested by Needleman [1] is modified to account for thermal effects. The MD results are employed to develop a parameterized cohesive zone model which is implemented in a finite element model of the matrix-particle interactions. Stress-strain curves obtained from simulations under different loading conditions and volume fractions show a close correlation with experimental results. Finally, by studying the effects of strain rate and volume fraction of particles in Al(6061-T6)/Al2O3 composite, an equivalent homogeneous model is introduced which can predict the overall behavior of the composite.

Electrical bistability and charge-transport mechanisms in cuprous sulfide nanosphere-poly(N-vinylcarbazole) composite films

International Nuclear Information System (INIS)

Tang Aiwei; Teng Feng; Liu Jie; Wang Yichao; Peng Hongshang; Hou Yanbing; Wang Yongsheng

2011-01-01

In this study, electrically bistable devices were fabricated by incorporating cuprous sulfide (Cu 2 S) nanospheres with mean size less than 10 nm into a poly(N-vinylcarbazole) (PVK) matrix. A remarkable electrical bistability was clearly observed in the current–voltage curves of the devices due to an electric-field-induced charge transfer between the dodecanethiol-capped Cu 2 S nanospheres and PVK. The maximum ON/OFF current ratio reached up to value as large as 10 4 , which was dependent on the mass ratios of Cu 2 S nanospheres to PVK, the amplitude of the scanning voltages, and the film thickness. The charge-transport mechanisms of the electrically bistable devices were described on the basis of the experimental results using different theoretical models of organic electronics.

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

Kinetic studies of sulfide mineral oxidation and xanthate adsorption

Science.gov (United States)

Mendiratta, Neeraj K.

2000-10-01

Sulfide minerals are a major source of metals; however, certain sulfide minerals, such as pyrite and pyrrhotite, are less desirable. Froth flotation is a commonly used separation technique, which requires the use of several reagents to float and depress different sulfide minerals. Xanthate, a thiol collector, has gained immense usage in sulfide minerals flotation. However, some sulfides are naturally hydrophobic and may float without a collector. Iron sulfides, such as pyrite and pyrrhotite, are few of the most abundant minerals, yet economically insignificant. Their existence with other sulfide minerals leads to an inefficient separation process as well as environmental problems, such as acid mine drainage during mining and processing and SO 2 emissions during smelting process. A part of the present study is focused on understanding their behavior, which leads to undesired flotation and difficulties in separation. The major reasons for the undesired flotation are attributed to the collectorless hydrophobicity and the activation with heavy metal ions. To better understand the collectorless hydrophobicity of pyrite, Electrochemical Impedance Spectroscopy (EIS) of freshly fractured pyrite electrodes was used to study the oxidation and reduction of the mineral. The EIS results showed that the rate of reaction increases with oxidation and reduction. At moderate oxidizing potentials, the rate of reaction is too slow to replenish hydrophilic iron species leaving hydrophobic sulfur species on the surface. However, at higher potentials, iron species are replaced fast enough to depress its flotation. Effects of pH and polishing were also explored using EIS. Besides collectorless hydrophobicity, the activation of pyrrhotite with nickel ions and interaction with xanthate ions makes the separation more difficult. DETA and SO2 are commonly used as pyrrhotite depressants; however, the mechanism is not very well understood. Contact angle measurements, cyclic voltammetry and Tafel

EBSD and EDS of nickel sulfide inclusions in glass

International Nuclear Information System (INIS)

Miflin, G.E.; Barry, J.C.

2002-01-01

Full text: A delayed phase transformation in small nickel sulfide inclusions can cause spontaneous fracture in toughened glass. Typically, a phase transformation within a 5 ?g nickel sulphide inclusion may break a window which weighs more than 50 kg. In most cases the nickel sulfide inclusions are detected only after window failure, although it is possible to detect the inclusions within intact glass. It is known that only type three nickel sulphide inclusions, that is, inclusions with a composition in the range Ni 7 S 6 to NiS 1.03 , break the glass. The solid-state phase transformation of alpha Ni 1-x S to beta NiS which induces a 2.5% volume increase has been given as the main reason for the spontaneous fracture. The aim of this present study is to investigate the crystal structure of phases within the type three inclusions using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). With EBSD it is possible to map regions of alpha Ni 1-x S and to distinguish those regions from regions with beta Ni 1-x S when the elemental compositions of the two regions are identical. The inclusions of this study came from two sources. One set of inclusions were found at initiation-of-fracture in glass windows that had failed by spontaneous fracture, while the other set were found in intact windows. All of the inclusions came from windows on buildings in the Brisbane area. The EBSD analysis was done at 20kV with the stage tilted to 70 degrees on a Philips XL30 SEM with LaB 6 filament, and with attached Oxford/Link Opal camera and software. EBSD mapping was done for alpha nickel sulfide (Ni 1-x S), beta nickel sulphide (NiS), heazelwoodite (Ni 3 S 2 ), and godlevskite (Ni 9 S 8 ). The integration time was 1.3 seconds for each point. Colour coded crystal phase and grain orientation maps were produced. EDS analysis was also done on the Philips XL30 with attached EDAX EDS detector. We found that although the EBSD technique is successful in identifying alpha

Remediation of arsenic-contaminated groundwater by in-situ stimulating biogenic precipitation of iron sulfides.

Science.gov (United States)

Pi, Kunfu; Wang, Yanxin; Xie, Xianjun; Ma, Teng; Liu, Yaqing; Su, Chunli; Zhu, Yapeng; Wang, Zhiqiang

2017-02-01

Severe health problems due to elevated arsenic (As) in groundwater have made it urgent to develop cost-effective technologies for As removal. This field experimental study tested the feasibility of in-situ As immobilization via As incorporation into newly formed biogenic Fe(II) sulfides in a typical As-affected strongly reducing aquifer at the central part of Datong Basin, China. After periodic supply of FeSO 4 into the aquifer for 25 d to stimulate microbial sulfate reduction, dissolved sulfide concentrations increased during the experiment, but the supplied Fe(II) reacted quickly with sulfide to form Fe(II)-sulfides existing majorly as mackinawite as well as a small amount of pyrite-like minerals in sediments, thereby restricting sulfide build-up in groundwater. After the completion of field experiment, groundwater As concentration decreased from an initial average value of 593 μg/L to 159 μg/L, with an overall As removal rate of 73%, and it further declined to 136 μg/L adding the removal rate up to 77% in 30 d after the experiment. The arsenite/As total ratio gradually increased over time, making arsenite to be the predominant species in groundwater residual As. The good correlations between dissolved Fe(II), sulfide and As concentrations, the increased abundance of As in newly-formed Fe sulfides as well as the reactive-transport modeling results all indicate that As could have been adsorbed onto and co-precipitated with Fe(II)-sulfide coatings once microbial sulfate reduction was stimulated after FeSO 4 supply. Under the strongly reducing conditions, sulfide may facilitate arsenate reduction into arsenite and promote As incorporation into pyrite or arsenopyrite. Therefore, the major mechanisms for the in-situ As-contaminated groundwater remediation can be As surface-adsorption on and co-precipitation with Fe(II) sulfides produced during the experimental period. Copyright © 2016. Published by Elsevier Ltd.

Problems of Chernobyl exclusion zone

International Nuclear Information System (INIS)

1996-01-01

The collection comprises the results of researches and design activity in the ChNPP exclusion zone with the aim to develop technology, equipment and instruments for RAW management and accident clean-up, studying of the composition and structure of the activity solid bearers in the soil of the exclusion zone and transformation of the radionuclides in the nearest zone of ChNPP. Much attention is paid to medical and biological problems of the accident influence on the flora, fauna and people's health labour conditions and incidence of the people involved

Problems of Chornobyl Exclusion Zone

International Nuclear Information System (INIS)

Kashparov, V.A.

2009-01-01

The collection comprises the results of researches and design activity in the ChNPP exclusion zone with the aim to develop technology, equipment and instruments for RAW management and accident clean-up, studying of the composition and structure of the activity solid bearers in the soil of the exclusion zone and transformation of the radionuclides in the nearest zone of ChNPP. Much attention is paid to medical and biological problems of the accident influence on the flora, fauna and people's health, labour conditions and incidence of the people involved.

Toxic metal(loid) speciation during weathering of iron sulfide mine tailings under semi-arid climate

Science.gov (United States)

Root, Robert A.; Hayes, Sarah M.; Hammond, Corin M.; Maier, Raina M.; Chorover, Jon

2015-01-01

Toxic metalliferous mine-tailings pose a significant health risk to ecosystems and neighboring communities from wind and water dispersion of particulates containing high concentrations of toxic metal(loid)s (e.g., Pb, As, Zn). Tailings are particularly vulnerable to erosion before vegetative cover can be reestablished, i.e., decades or longer in semi-arid environments without intervention. Metal(loid) speciation, linked directly to bioaccessibility and lability, is controlled by mineral weathering and is a key consideration when assessing human and environmental health risks associated with mine sites. At the semi-arid Iron King Mine and Humboldt Smelter Superfund site in central Arizona, the mineral assemblage of the top 2 m of tailings has been previously characterized. A distinct redox gradient was observed in the top 0.5 m of the tailings and the mineral assemblage indicates progressive transformation of ferrous iron sulfides to ferrihydrite and gypsum, which, in turn weather to form schwertmannite and then jarosite accompanied by a progressive decrease in pH (7.3 to 2.3). Within the geochemical context of this reaction front, we examined enriched toxic metal(loid)s As, Pb, and Zn with surficial concentrations 41.1, 10.7, 39.3 mM kg-1 (3080, 2200, and 2570 mg kg-1), respectively. The highest bulk concentrations of As and Zn occur at the redox boundary representing a 1.7 and 4.2 fold enrichment relative to surficial concentrations, respectively, indicating the translocation of toxic elements from the gossan zone to either the underlying redox boundary or the surface crust. Metal speciation was also examined as a function of depth using X-ray absorption spectroscopy (XAS). The deepest sample (180 cm) contains sulfides (e.g., pyrite, arsenopyrite, galena, and sphalerite). Samples from the redox transition zone (25-54 cm) contain a mixture of sulfides, carbonates (siderite, ankerite, cerrusite, and smithsonite) and metal(loid)s sorbed to neoformed secondary Fe

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

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......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...... of film formation in sulfide solutins was followed by video. It can be shown that capacitative and diffusional effects due to porous reactive deposits tend to dominate the data, resulting in unreliable corrosion rates measured using electrochemical techniques. The effect is strongly increased...

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...... 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...

Electrochemical oxidation of iron and alkalinity generation for efficient sulfide control in sewers.

Science.gov (United States)

Lin, Hui-Wen; Kustermans, Caroline; Vaiopoulou, Eleni; Prévoteau, Antonin; Rabaey, Korneel; Yuan, Zhiguo; Pikaar, Ilje

2017-07-01

The addition of iron salts is one of the most commonly used dosing strategies for sulfide control in sewers. However, iron salts decrease the sewage pH which not only reduces the effectiveness of sulfide precipitation but also enhances the release of residual sulfide to the sewer atmosphere. Equally important, concentrated iron salt solutions are corrosive and their frequent transport, handling, and on-site storage often come with Occupational Health and Safety (OH&S) concerns. Here, we experimentally demonstrated a novel sulfide control approach using electrochemical systems with parallel placed iron electrodes. This enabled combining anodic dissolved iron species release with cathodic hydroxyl anion production, which alleviates all the aforementioned concerns. A long-term experiment was successfully carried out achieving an average sulfide removal efficiency of 95.4 ± 4.4% at low voltage input of 2.90 ± 0.54 V over the course of 8 weeks. This electrochemical method was demonstrated to successfully achieve efficient sulfide control. In addition, it increases the sewage pH, thereby overcoming the drawbacks associated with the pH decrease in the case of conventional iron salt dosing. Ferrous ions were produced at an overall coulombic efficiency (CE) of 98.2 ± 1.2%, whereas oxygen evolution and direct sulfide oxidation were not observed. Short-term experiments showed that increasing either inter-electrode gap or current density increased the cell voltage associated with the increase in the ohmic drop of the system. Overall, this study highlights the practical potential of in-situ generation of dissolved iron species and simultaneous hydroxyl anion generation for efficient sulfide control in sewers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Corrosion Behavior of Cu40Zn in Sulfide-Polluted 3.5% NaCl Solution

Science.gov (United States)

Song, Q. N.; Xu, N.; Bao, Y. F.; Jiang, Y. F.; Gu, W.; Yang, Z.; Zheng, Y. G.; Qiao, Y. X.

2017-10-01

The corrosion behavior of a duplex-phase brass Cu40Zn in clean and sulfide-polluted 3.5% NaCl solutions was investigated by conducting electrochemical and gravimetric measurements. The corrosion product films were analyzed by scanning electron microscopy, energy-dispersive spectroscopy and x-ray diffraction. The presence of sulfide shifted the corrosion potential of Cu40Zn toward a more negative value by 100 mV and increased the mass loss rate by a factor of 1.257 compared with the result in the clean solution. The corrosion product film in the clean solution was thin and compact; it mainly consisted of oxides, such as ZnO and Cu2O. By contrast, the film in the sulfide-polluted solution was thick and porous. It mainly contained sulfides and zinc hydroxide chloride (i.e., Zn5(OH)8Cl2·H2O). The presence of sulfide ions accelerated the corrosion damage of Cu40Zn by hindering the formation of protective oxides and promoting the formation of a defective film which consisted of sulfides and hydroxide chlorides.

Sulfide stress corrosion study of a super martensitic stainless steel in H2S sour environments: Metallic sulfides formation and hydrogen embrittlement

Science.gov (United States)

Monnot, Martin; Nogueira, Ricardo P.; Roche, Virginie; Berthomé, Grégory; Chauveau, Eric; Estevez, Rafael; Mantel, Marc

2017-02-01

Thanks to their high corrosion resistance, super martensitic stainless steels are commonly used in the oil and gas industry, particularly in sour environments. Some grades are however susceptible to undergo hydrogen and mechanically-assisted corrosion processes in the presence of H2S, depending on the pH. The martensitic stainless steel EN 1.4418 grade exhibits a clear protective passive behavior with no sulfide stress corrosion cracking when exposed to sour environments of pH ≥ 4, but undergoes a steep decrease in its corrosion resistance at lower pH conditions. The present paper investigated this abrupt loss of corrosion resistance with electrochemical measurements as well as different physicochemical characterization techniques. Results indicated that below pH 4.0 the metal surface is covered by a thick (ca 40 μm) porous and defect-full sulfide-rich corrosion products layer shown to be straightforwardly related to the onset of hydrogen and sulfide mechanically-assisted corrosion phenomena.

Stable catalyst layers for hydrogen permeable composite membranes

Science.gov (United States)

Way, J. Douglas; Wolden, Colin A

2014-01-07

The present invention provides a hydrogen separation membrane based on nanoporous, composite metal carbide or metal sulfide coated membranes capable of high flux and permselectivity for hydrogen without platinum group metals. The present invention is capable of being operated over a broad temperature range, including at elevated temperatures, while maintaining hydrogen selectivity.

Investigations on the role of hemoglobin in sulfide metabolism by intact human red blood cells.

Science.gov (United States)

Bianco, Christopher L; Savitsky, Anton; Feelisch, Martin; Cortese-Krott, Miriam M

2018-03-01

In addition to their role as oxygen transporters, red blood cells (RBCs) contribute to cardiovascular homeostasis by regulating nitric oxide (NO) metabolism via interaction of hemoglobin (Hb) with nitrite and NO itself. RBCs were proposed to also participate in sulfide metabolism. Although Hb is known to react with sulfide, sulfide metabolism by intact RBCs has not been characterized so far. Therefore we explored the role of Hb in sulfide metabolism in intact human RBCs. We find that upon exposure of washed RBCs to sulfide, no changes in oxy/deoxyhemoglobin (oxy/deoxyHb) are observed by UV-vis and EPR spectroscopy. However, sulfide reacts with methemoglobin (metHb), forming a methemoglobin-sulfide (metHb-SH) complex. Moreover, while metHb-SH is stable in cell-free systems even in the presence of biologically relevant thiols, it gradually decomposes to produce oxyHb, inorganic polysulfides and thiosulfate in intact cells, as detected by EPR and mass spectrometry. Taken together, our results demonstrate that under physiological conditions RBCs are able to metabolize sulfide via intermediate formation of a metHb-SH complex, which subsequently decomposes to oxyHb. We speculate that decomposition of metHb-SH is preceded by an inner-sphere electron transfer, forming reduced Hb (which binds oxygen to form oxyHb) and thiyl radical (a process we here define as "reductive sulfhydration"), which upon release, gives rise to the oxidized products, thiosulfate and polysulfides. Thus, not only is metHb an efficient scavenger and regulator of sulfide in blood, intracellular sulfide itself may play a role in keeping Hb in the reduced oxygen-binding form and, therefore, be involved in RBC physiology and function. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Preparation of transition metal sulfide nanoparticles via hydrothermal route

International Nuclear Information System (INIS)

Fei-Ling, P.; Chin-Hua, C.; Sarani Zakaria; Tze-Khong, L.; Mohd Ambar Yarmo; Nay-Ming, H.

2010-01-01

Nano sized copper sulfide, iron sulfide and molybdenum sulfide were successfully synthesised via a simple hydrothermal method. Sodium thiosulfate pentahydrate (Na 2 S 2 O 3 ·5H 2 O) and hydroxylamine sulfate ((H 3 NO) 2 ·H 2 SO 4 ) were used as the starting materials and reacted with the transition metal source at 200 degree Celsius for 90 min. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR). Spherical shape CuS and FeS 2 nanoparticles with high crystallinity were successfully produced. The transmission electron micrographs revealed the well-dispersibility of the produced nanoparticles. Scanning electron micrograph showed the MoS 2 nanoparticles possessed a spherical shape with sheet-like structure covering on the outer surface of the particles. (author)

The lithiation and acyl transfer reactions of phosphine oxides, sulfides and boranes in the synthesis of cyclopropanes

DEFF Research Database (Denmark)

Clarke, Celia; Fox, David J; Pedersen, Daniel Sejer

2009-01-01

Phosphine oxides are lithiated much faster than phosphine sulfides and phosphine boranes. Phosphine sulfides are in turn lithiated much more readily than phosphine boranes. It was possible to trap a phosphine sulfide THF in one case which upon treatment with t-BuOK gave cyclopropane, showing...... that phosphine sulfides readily undergo both phosphinoyl transfer and cyclopropane ring closure just like their phosphine oxide counterparts. The obtained data show that phosphine oxides are easily lithiated and undergo phosphoryl transfer much more readily and faster than phosphine sulfides and phosphine...... boranes. The observations suggest that it would be possible to perform reactions involving phosphine oxides in the presence of phosphine boranes or phosphine sulfides, potentially allowing regioselective alkylation of phosphine oxides in the presence of phosphine boranes or phosphine sulfides....

Synthesis of zinc sulfide by chemical vapor deposition using an organometallic precursor: Di-tertiary-butyl-disulfide

International Nuclear Information System (INIS)

Vasekar, Parag; Dhakal, Tara; Ganta, Lakshmikanth; Vanhart, Daniel; Desu, Seshu

2012-01-01

Zinc sulfide has gained popularity in the last few years as a cadmium-free heterojunction partner for thin film solar cells and is seen as a good replacement for cadmium sulfide due to better blue photon response and non-toxicity. In this work, zinc sulfide films are prepared using an organic sulfur source. We report a simple and repeatable process for development of zinc sulfide using a cost-effective and less hazardous organic sulfur source. The development of zinc sulfide has been studied on zinc oxide-coated glass where the zinc oxide is converted into zinc sulfide. Zinc oxide grown by atomic layer deposition as well as commercially available zinc oxide-coated glass was used. The zinc sulfide synthesis has been studied and the films are characterized using scanning electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and a UV–VIS spectrophotometer. XRD, XPS and optical characterization confirm the zinc sulfide phase formation. - Highlights: ► Synthesis of ZnS using a less-hazardous precursor, di-tertiary-butyl-disulfide. ► ZnS process optimized for two types of ZnO films. ► Preliminary results for a solar cell show an efficiency of 1.09%.

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

Effect of sulfide concentration on the location of the metal precipitates in inversed fluidized bed reactors

Energy Technology Data Exchange (ETDEWEB)

Villa-Gomez, D., E-mail: d.villagomez@unesco-ihe.org [Core Pollution Prevention and Control, UNESCO-IHE, Institute for Water Education, PO Box 3015, 2601 DA Delft (Netherlands); Ababneh, H.; Papirio, S.; Rousseau, D.P.L.; Lens, P.N.L. [Core Pollution Prevention and Control, UNESCO-IHE, Institute for Water Education, PO Box 3015, 2601 DA Delft (Netherlands)

2011-08-15

Highlights: {yields} Sulfide concentration governs the location of metal precipitates in sulfate reducing bioreactors. {yields} High dissolved sulfide induces metal precipitation in the bulk liquid as fines. {yields} Low dissolved sulfide concentrations yield local supersaturation and thus metal precipitation in the biofilm. -- Abstract: The effect of the sulfide concentration on the location of the metal precipitates within sulfate-reducing inversed fluidized bed (IFB) reactors was evaluated. Two mesophilic IFB reactors were operated for over 100 days at the same operational conditions, but with different chemical oxygen demand (COD) to SO{sub 4}{sup 2-} ratio (5 and 1, respectively). After a start up phase, 10 mg/L of Cu, Pb, Cd and Zn each were added to the influent. The sulfide concentration in one IFB reactor reached 648 mg/L, while it reached only 59 mg/L in the other one. In the high sulfide IFB reactor, the precipitated metals were mainly located in the bulk liquid (as fines), whereas in the low sulfide IFB reactor the metal preciptiates were mainly present in the biofilm. The latter can be explained by local supersaturation due to sulfide production in the biofilm. This paper demonstrates that the sulfide concentration needs to be controlled in sulfate reducing IFB reactors to steer the location of the metal precipitates for recovery.

Hydrogen sulfide production from subgingival plaque samples.

Science.gov (United States)

Basic, A; Dahlén, G

2015-10-01

Periodontitis is a polymicrobial anaerobe infection. Little is known about the dysbiotic microbiota and the role of bacterial metabolites in the disease process. It is suggested that the production of certain waste products in the proteolytic metabolism may work as markers for disease severity. Hydrogen sulfide (H2S) is a gas produced by degradation of proteins in the subgingival pocket. It is highly toxic and believed to have pro-inflammatory properties. We aimed to study H2S production from subgingival plaque samples in relation to disease severity in subjects with natural development of the disease, using a colorimetric method based on bismuth precipitation. In remote areas of northern Thailand, adults with poor oral hygiene habits and a natural development of periodontal disease were examined for their oral health status. H2S production was measured with the bismuth method and subgingival plaque samples were analyzed for the presence of 20 bacterial species with the checkerboard DNA-DNA hybridization technique. In total, 43 subjects were examined (age 40-60 years, mean PI 95 ± 6.6%). Fifty-six percent had moderate periodontal breakdown (CAL > 3  7 mm) on at least one site. Parvimonas micra, Filifactor alocis, Porphyromonas endodontalis and Fusobacterium nucleatum were frequently detected. H2S production could not be correlated to periodontal disease severity (PPD or CAL at sampled sites) or to a specific bacterial composition. Site 21 had statistically lower production of H2S (p = 0.02) compared to 16 and 46. Betel nut chewers had statistically significant lower H2S production (p = 0.01) than non-chewers. Rapid detection and estimation of subgingival H2S production capacity was easily and reliably tested by the colorimetric bismuth sulfide precipitation method. H2S may be a valuable clinical marker for degradation of proteins in the subgingival pocket. Copyright © 2014 Elsevier Ltd. All rights reserved.

Sythesis of metal sulfide nanomaerials via thermal decomposition of single-source percursors

Energy Technology Data Exchange (ETDEWEB)

Jen-La Plante, Ilan; Zeid, Tahani W.; Yang, Peidong; Mokari, Taleb

2010-06-03

In this report, we present a synthetic method for the formation of cuprous sulfide (Cu2S) and lead sulfide (PbS) nanomaterials directly on substrates from the thermolysis of single-source precursors. We find that the final morphology and arrangement of the nanomaterials may be controlled through the concentration of the dissolved precursors and choice of solvent. One-dimensional (1-D) morphologies may also be grown onto substrates with the addition of a metal catalyst layer through solution-liquid-solid (SLS) growth. These synthetic techniques may be expanded to other metal sulfide materials.

A physiologically based kinetic model for bacterial sulfide oxidation.

Science.gov (United States)

Klok, Johannes B M; de Graaff, Marco; van den Bosch, Pim L F; Boelee, Nadine C; Keesman, Karel J; Janssen, Albert J H

2013-02-01

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 concluded that the oxidation-reduction state of cytochrome c is a direct measure for the bacterial end-product formation. Given this physiological feature, incorporation of the oxidation state of cytochrome c in a mathematical model for the bacterial oxidation kinetics will yield a physiologically based model structure. This paper presents a physiologically based model, describing the dynamic formation of the various end-products in the biodesulfurization process. It consists of three elements: 1) Michaelis-Menten kinetics combined with 2) a cytochrome c driven mechanism describing 3) the rate determining enzymes of the respiratory system of haloalkaliphilic sulfide oxidizing bacteria. The proposed model is successfully validated against independent data obtained from biological respiration tests and bench scale gas-lift reactor experiments. The results demonstrate that the model is a powerful tool to describe product formation for haloalkaliphilic biomass under dynamic conditions. The model predicts a maximum S⁰ formation of about 98 mol%. A future challenge is the optimization of this bioprocess by improving the dissolved oxygen control strategy and reactor design. Copyright © 2012 Elsevier Ltd. All rights reserved.

ELECTROCHEMICAL DETERMINATION OF HYDROGEN SULFIDE AT CARBON NANOTUBE MODIFIED ELECTRODES. (R830900)

Science.gov (United States)

Carbon nanotube (CNT) modified glassy carbon electrodes exhibiting a strong and stable electrocatalytic response towards sulfide are described. A substantial (400 mV) decrease in the overvoltage of the sulfide oxidation reaction (compared to ordinary carbon electrodes) is...

Analysis of compositional monosaccharides in fungus polysaccharides by capillary zone electrophoresis.

Science.gov (United States)

Hu, Yuanyuan; Wang, Tong; Yang, Xingbin; Zhao, Yan

2014-02-15

A rapid analytical method of capillary zone electrophoresis (CZE) was established for the simultaneous separation and determination of 10 monosaccharides (aldoses and uronic acids). The monosaccharides were labeled with 1-phenyl-3-methyl-5-pyrazolone (PMP), and subsequently separated using an uncoated capillary (50 μm i.d. × 58.5 cm) and detected by UV at 245 nm with pH 11.0, 175 mM borate buffer at voltage 20 kV and capillary temperature 25 °C by CZE. The 10 PMP-labeled monosaccharides were rapidly baseline separated within 20 min. The optimized CZE method was successfully applied to the simultaneous separation and identification of the monosaccharide composition in Termitomyces albuminosus polysaccharides (TAPs) and Panus giganteus polysaccharides (PGPs). The quantitative recovery of the component monosaccharides in the fungus polysaccharides was in the range of 92.0-101.0% and the CV value was lower than 3.5%. The results demonstrate that the proposed CZE method is precise and practical for the monosaccharide analysis of fungus polysaccharides. Copyright © 2013 Elsevier Ltd. All rights reserved.

Radial mixing of material in the asterodial zone

International Nuclear Information System (INIS)

Ruzmaikina, T.V.; Safronov, V.S.; Weidenschilling, S.J.

1989-01-01

The asteroid belt shows radial zoning of compositional structure. The most abundant types are successively S, C and P types from the inner to the outer parts of the main belt, and D type in the Trojan clouds. Boundaries between compositional zones are not sharp, but gradual transitions over scales ∼1 AU in semimajor axis. The authors examine processes for producing this structure before, during and after the accretion of asteroids. The initial structure is established by temperature and composition gradients in the turbulent solar nebula during the collapse of the presolar cloud. The radial scale of the zoning, comparable to the disk thickness, favors disk models with relatively low turbulent viscosity. Radial decay of solid bodies due to gas drag during settling to the central plane and planetesimal formation probably causes only a small degree of mixing, due to the systematic nature of drag-induced motions

A real support effect on the hydrodeoxygenation of methyl oleate by sulfided NiMo catalysts

NARCIS (Netherlands)

Coumans, A.E.; Hensen, E.J.M.

2017-01-01

The effect of the support on the catalytic performance of sulfided NiMo in the hydrodeoxygenation of methyl oleate as a model compound for triglyceride upgrading to green diesel was investigated. NiMo sulfides were prepared by impregnation and sulfidation on activated carbon, silica, γ-alumina and

Sulfide Mineral Surfaces

International Nuclear Information System (INIS)

Rosso, Kevin M.; Vaughan, David J.

2006-01-01

The past twenty years or so have seen dramatic development of the experimental and theoretical tools available to study the surfaces of solids at the molecular (?atomic resolution?) scale. On the experimental side, two areas of development well illustrate these advances. The first concerns the high intensity photon sources associated with synchrotron radiation; these have both greatly improved the surface sensitivity and spatial resolution of already established surface spectroscopic and diffraction methods, and enabled the development of new methods for studying surfaces. The second centers on the scanning probe microscopy (SPM) techniques initially developed in the 1980's with the first scanning tunneling microscope (STM) and atomic force microscope (AFM) experiments. The direct 'observation' of individual atoms at surfaces made possible with these methods has truly revolutionized surface science. On the theoretical side, the availability of high performance computers coupled with advances in computational modeling has provided powerful new tools to complement the advances in experiment. Particularly important have been the quantum mechanics based computational approaches such as density functional theory (DFT), which can now be easily used to calculate the equilibrium crystal structures of solids and surfaces from first principles, and to provide insights into their electronic structure. In this chapter, we review current knowledge of sulfide mineral surfaces, beginning with an overview of the principles relevant to the study of the surfaces of all crystalline solids. This includes the thermodynamics of surfaces, the atomic structure of surfaces (surface crystallography and structural stability, adjustments of atoms at the surface through relaxation or reconstruction, surface defects) and the electronic structure of surfaces. We then discuss examples where specific crystal surfaces have been studied, with the main sulfide minerals organized by structure type

Sulfide Mineral Surfaces

Energy Technology Data Exchange (ETDEWEB)

Rosso, Kevin M.; Vaughan, David J.

2006-08-01

The past twenty years or so have seen dramatic development of the experimental and theoretical tools available to study the surfaces of solids at the molecular (?atomic resolution?) scale. On the experimental side, two areas of development well illustrate these advances. The first concerns the high intensity photon sources associated with synchrotron radiation; these have both greatly improved the surface sensitivity and spatial resolution of already established surface spectroscopic and diffraction methods, and enabled the development of new methods for studying surfaces. The second centers on the scanning probe microscopy (SPM) techniques initially developed in the 1980's with the first scanning tunneling microscope (STM) and atomic force microscope (AFM) experiments. The direct 'observation' of individual atoms at surfaces made possible with these methods has truly revolutionized surface science. On the theoretical side, the availability of high performance computers coupled with advances in computational modeling has provided powerful new tools to complement the advances in experiment. Particularly important have been the quantum mechanics based computational approaches such as density functional theory (DFT), which can now be easily used to calculate the equilibrium crystal structures of solids and surfaces from first principles, and to provide insights into their electronic structure. In this chapter, we review current knowledge of sulfide mineral surfaces, beginning with an overview of the principles relevant to the study of the surfaces of all crystalline solids. This includes the thermodynamics of surfaces, the atomic structure of surfaces (surface crystallography and structural stability, adjustments of atoms at the surface through relaxation or reconstruction, surface defects) and the electronic structure of surfaces. We then discuss examples where specific crystal surfaces have been studied, with the main sulfide minerals organized by

Composition of Whiskers Grown on Copper in Repository Environment

International Nuclear Information System (INIS)

Hermansson, Hans-Peter; Tarkpea, Peeter; Holgersson, Stellan

2001-11-01

There is a hypothesis that a special family of local attack on copper based on growth of whiskers of sulfide, oxide/hydroxide and also carbonate/malachite could appear in the repository environment. It was earlier demonstrated that such whiskers could grow in a laboratory simulated repository environment, containing sulfide. A suggested composition of whiskers has earlier been forwarded but was not demonstrated. In the present work whiskers and their substrates were grown and characterized by investigations with a combination of SEM-EDS, XRD and LRS (Laser Raman Spectroscopy) techniques. SEM-EDS was used to determine the morphology and an elemental composition and distribution of whiskers and their substrate. A special effort was made to find out if the whisker growth is of a local or global character. The phase status could be determined locally and globally by combining XRD and LRS techniques on whiskers and substrates. Ideally, LRS gives a phase resolution down to a radius of 1 μm on the sample surface. This is of great value as it is of interest to study if there are phase differences in different parts of a whisker. Such information is important to understand the whisker growth mechanism. Cylindrical samples of pure copper were prepared and exposed to the selected de-aerated model groundwater containing, among other ions, chloride and sulfide. Exposure was performed in sealed glass flasks under de-aerated conditions. After exposure the copper sample was investigated on the surface, in cross section and on whiskers using the mentioned techniques. The results show that a black, easily detached layer of corrosion products is formed on the sample surface. The corrosion layer was subdivided into at least five parallel strata (probably more) of different composition. Numerous small pits and shallow pitting attacks with a larger radius were observed in the copper metal and the metal surface was in general very rough. A multitude of very easily detached whiskers or

Room temperature synthesis of ReS2 through aqueous perrhenate sulfidation

Science.gov (United States)

Borowiec, Joanna; Gillin, William P.; Willis, Maureen A. C.; Boi, Filippo S.; He, Y.; Wen, J. Q.; Wang, S. L.; Schulz, Leander

2018-02-01

In this study, a direct sulfidation reaction of ammonium perrhenate (NH4ReO4) leading to a synthesis of rhenium disulfide (ReS2) is demonstrated. These findings reveal the first example of a simplistic bottom-up approach to the chemical synthesis of crystalline ReS2. The reaction presented here takes place at room temperature, in an ambient and solvent-free environment and without the necessity of a catalyst. The atomic composition and structure of the as-synthesized product were characterized using several analysis techniques including energy dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, x-ray diffraction, transmission electron microscopy, Raman spectroscopy, thermogravimetric analysis and differential scanning calorimetry. The results indicated the formation of a lower symmetry (1Tʹ) ReS2 with a low degree of layer stacking.

Combined DC resistivity and induced polarization (DC-IP) for mapping the internal composition of a mine waste rock pile in Nova Scotia, Canada

Science.gov (United States)

Power, Christopher; Tsourlos, Panagiotis; Ramasamy, Murugan; Nivorlis, Aristeidis; Mkandawire, Martin

2018-03-01

Mine waste rock piles (WRPs) can contain sulfidic minerals whose interaction with oxygen and water can generate acid mine drainage (AMD). Thus, WRPs can be a long-term source of environmental pollution. Since the generation of AMD and its release into the environment is dependent on the net volume and bulk composition of waste rock, effective characterization of WRPs is necessary for successful remedial design and monitoring. In this study, a combined DC resistivity and induced polarization (DC-IP) approach was employed to characterize an AMD-generating WRP in the Sydney Coalfield, Nova Scotia, Canada. Two-dimensional (2D) DC-IP imaging with 6 survey lines was performed to capture the full WRP landform. 2D DC results indicated a highly heterogeneous and moderately conductive waste rock underlain by a resistive bedrock containing numerous fractures. 2D IP (chargeability) results identified several highly-chargeable regions within the waste, with normalized chargeability delineating regions specific to waste mineralogy only. Three-dimensional (3D) DC-IP imaging, using 17 parallel lines on the plateau of the pile, was then used to focus on the composition of the waste rock. The full 3D inverted DC-IP distributions were used to identify coincident and continuous zones (isosurfaces) of low resistivity (0.4 mS/m) that were inferred as generated AMD (leachate) and stored AMD (sulfides), respectively. Integrated geological, hydrogeological and geochemical data increased confidence in the geoelectrical interpretations. Knowledge on the location of potentially more reactive waste material is extremely valuable for improved long-term AMD monitoring at the WRP.

Remediation of Cd-contaminated soil around metal sulfide mines

Science.gov (United States)

Lu, Xinzhe; Hu, Xuefeng; Kang, Zhanjun; Luo, Fan

2017-04-01

The mines of metal sulfides are widely distributed in the southwestern part of Zhejiang Province, Southeast China. The activities of mining, however, often lead to the severe pollution of heavy metals in soils, especially Cd contamination. According to our field investigations, the spatial distribution of Cd-contaminated soils is highly consistent with the presence of metal sulfide mines in the areas, further proving that the mining activities are responsible for Cd accumulation in the soils. To study the remediation of Cd-contaminated soils, a paddy field nearby large sulfide mines, with soil pH 6 and Cd more than 1.56 mg kg-1, five times higher than the national recommended threshold, was selected. Plastic boards were deeply inserted into soil to separate the field and make experimental plots, with each plot being 4 m×4 m. Six treatments, TK01˜TK06, were designed to study the effects of different experimental materials on remediating Cd-contaminated soils. The treatment of TK01 was the addition of 100 kg zeolites to the plot; TK02, 100 kg apatites; TK03, 100 kg humid manure; TK04, 50 kg zeolites + 50 kg apatites; TK05, 50 kg zeolites + 50 kg humid manure; TK06 was blank control (CK). One month after the treatments, soil samples at the plots were collected to study the possible change of chemical forms of Cd in the soils. The results indicated that these treatments reduced the content of available Cd in the soils effectively, by a decreasing sequence of TK04 (33%) > TK02 (25%) > TK01 (23%) > TK05 (22%) > TK03 (15%), on the basis of CK. Correspondingly, the treatments also reduced the content of Cd in rice grains significantly, by a similar decreasing sequence of TK04 (83%) > TK02 (77%) > TK05 (63%) > TK01 (47%) > TK03 (27%). The content of Cd in the rice grains was 0.071 mg kg-1, 0.094 mg kg-1, 0.159 mg kg-1, 0.22 mg kg-1 and 0.306 mg kg-1, respectively, compared with CK, 0.418 mg kg-1. This experiment suggested that the reduction of available Cd in the soils is

Seasonality of major redox constituents in a shallow subterranean estuary

Science.gov (United States)

O'Connor, Alison E.; Krask, Julie L.; Canuel, Elizabeth A.; Beck, Aaron J.

2018-03-01

The subterranean estuary (STE), the subsurface mixing zone of outflowing fresh groundwater and infiltrating seawater, is an area of extensive geochemical reactions that determine the composition of groundwater that flows into coastal environments. This study examined the porewater composition of a shallow STE (redox gradients on STE geochemistry. Two freshwater endmembers were identified, between which redox potential and composition varied with depth-a shallow freshwater endmember was oxidizing and high in DOC, whereas a deep freshwater endmember was reducing, lower in DOC, and high in sulfide. Results showed that dissolved Fe, Mn, and sulfide varied along a redox gradient distinct from the salinity gradient, and that three-endmember mixing was required to quantify non-conservative chemical addition/removal in the STE. In addition to salinity, humic carbon was used as a quasi-conservative tracer to quantify mixing according to a three-endmember model. The vertical distributions of DOC and reduced metabolites remained approximately constant over time, but concentrations varied with season. Dissolved organic carbon concentrations were greatest in the summer, and shallow meteoric groundwater supplied the majority of DOC to the STE. In summer, there was additional evidence for shallow non-conservative addition of DOC. Dissolved Fe and Mn were highest in a subsurface plume through the middle of the STE (100-140 cm below sediment surface at the high tide line) which was characterized by higher concentrations and greater non-conservative addition in the winter. In contrast, sulfide was higher in summer at depths within the Fe and Mn plume (100-140 cm). We attribute the contrasting seasonal patterns of dissolved Fe, Mn, and sulfide to differences in microbial response to temperature changes and organic matter availability, and to competition at the ferrous-sulfidic transition zone between dissimilatory metal reduction and sulfate reduction, leading to sulfate

New technology for sulfide reductions and increased oil recovery: Petroleum project fact sheet

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-12-14

This Fact Sheet is written for the Inventions and Innovations Program about a new technology for sulfide reduction and increased oil recovery. The new technology, called Bio-Competitive Exclusion (BCX), results in greater oil production and prevents the production of corrosive hydrogen sulfide in oil and gas reservoirs. This BCX process is initiated and maintained by a new product, called Max-Well 2000, in which nutrients are custom designed to stimulate targeted beneficial microorganisms that live in every oil and gas reservoir. Rapid growth of these microorganisms excludes activity of harmful sulfide-producing bacteria and produces by-products that serve as effective tertiary oil recovery agents and as sulfide degradation agents. Oil and gas production is both increased and sweetened.

Current floristic composition, life form and productivity of the grasslands in the Hunting Zone of Djona (Benin)

DEFF Research Database (Denmark)

Ahoudji, Myrese C.; Teka, Oscar; Axelsen, Jørgen Aagaard

2014-01-01

Objectives: This paper addressed temporal changes in floristic composition, plant communities’ structures and productivity of grasslands. The study was conducted in the Hunting zone of Djona in the Transboundary Biosphere Reserve of W (TBRW) Benin. Methodology and Results: For these purpose 30...... plots of 900m² were used and “phytosociological relevés” were done following ecological uniformity, floristic homogeneity and samples representativeness to established plants communities. Biomass was estimated in 30 plots of 100 m². Results showed that the greatest productivity value (8320 ± 0.21 kg DM...... with broad distribution. Conclusions and application of findings: The identified life forms and chorological types showed an evolution of the post farming pastures to woodlands and savannas vegetation, which explains the current floristic composition of the area. Moreover, it will be possible to model...

When Al-Doped Cobalt Sulfide Nanosheets Meet Nickel Nanotube Arrays: A Highly Efficient and Stable Cathode for Asymmetric Supercapacitors.

Science.gov (United States)

Huang, Jun; Wei, Junchao; Xiao, Yingbo; Xu, Yazhou; Xiao, Yujuan; Wang, Ying; Tan, Licheng; Yuan, Kai; Chen, Yiwang

2018-03-27

Although cobalt sulfide is a promising electrode material for supercapacitors, its wide application is limited by relative poor electrochemical performance, low electrical conductivity, and inefficient nanostructure. Here, we demonstrated that the electrochemical activity of cobalt sulfide could be significantly improved by Al doping. We designed and fabricated hierarchical core-branch Al-doped cobalt sulfide nanosheets anchored on Ni nanotube arrays combined with carbon cloth (denoted as CC/H-Ni@Al-Co-S) as an excellent self-standing cathode for asymmetric supercapacitors (ASCs). The combination of structural and compositional advantages endows the CC/H-Ni@Al-Co-S electrode with superior electrochemical performance with high specific capacitance (1830 F g -1 /2434 F g -1 at 5 mV s -1 /1 A g -1 ) and excellent rate capability (57.2%/72.3% retention at 1000 mV s -1 /100 A g -1 ). The corresponding all-solid-state ASCs with CC/H-Ni@Al-Co-S and multilayer graphene/CNT film as cathode and anode, respectively, achieve a high energy density up to 65.7 W h kg -1 as well as superb cycling stability (90.6% retention after 10 000 cycles). Moreover, the ASCs also exhibit good flexibility and stability under different bending conditions. This work provides a general, effective route to prepare high-performance electrode materials for flexible all-solid-state energy storage devices.

Sulfide Generation by Dominant Halanaerobium Microorganisms in Hydraulically Fractured Shales

Energy Technology Data Exchange (ETDEWEB)

Booker, Anne E.; Borton, Mikayla A.; Daly, Rebecca A.; Welch, Susan A.; Nicora, Carrie D.; Hoyt, David W.; Wilson, Travis; Purvine, Samuel O.; Wolfe, Richard A.; Sharma, Shikha; Mouser, Paula J.; Cole, David R.; Lipton, Mary S.; Wrighton, Kelly C.; Wilkins, Michael J.; McMahon, Katherine

2017-07-05

Hydraulic fracturing of black shale formations has greatly increased United States oil and natural gas recovery. However, the accumulation of biomass in subsurface reservoirs and pipelines is detrimental because of possible well souring, microbially induced corrosion, and pore clogging. Temporal sampling of produced fluids from a well in the Utica Shale revealed the dominance ofHalanaerobiumstrains within thein situmicrobial community and the potential for these microorganisms to catalyze thiosulfate-dependent sulfidogenesis. From these field data, we investigated biogenic sulfide production catalyzed by aHalanaerobiumstrain isolated from the produced fluids using proteogenomics and laboratory growth experiments. Analysis ofHalanaerobiumisolate genomes and reconstructed genomes from metagenomic data sets revealed the conserved presence of rhodanese-like proteins and anaerobic sulfite reductase complexes capable of converting thiosulfate to sulfide. Shotgun proteomics measurements using aHalanaerobiumisolate verified that these proteins were more abundant when thiosulfate was present in the growth medium, and culture-based assays identified thiosulfate-dependent sulfide production by the same isolate. Increased production of sulfide and organic acids during the stationary growth phase suggests that fermentativeHalanaerobiumuses thiosulfate to remove excess reductant. These findings emphasize the potential detrimental effects that could arise from thiosulfate-reducing microorganisms in hydraulically fractured shales, which are undetected by current industry-wide corrosion diagnostics.

IMPORTANCEAlthough thousands of wells in deep shale formations across the United States have been hydraulically fractured for oil and gas recovery, the impact of microbial metabolism within these environments is poorly understood. Our

Effect of pre-oxidation on high temperature sulfidation behavior of FeCr and FeCrAl alloys

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Pillis Marina Fuser

2004-01-01

Full Text Available High temperature corrosion of structural alloys in sulfur bearing environments is many orders of magnitude higher than in oxidizing environments. Efforts to increase sulfidation resistance of these alloys include addition of alloying elements. Aluminum additions to iron-chromium alloys bring about increase in sulfidation resistance. This paper reports the effect of pre-oxidation on the sulfidation behavior of Fe-20Cr and Fe-20Cr-5Al alloys in H2-2% H2S environment at 800 °C. The surfaces of sulfidized specimens were also examined. Pre-oxidation of the two alloys results in an incubation period during subsequent sulfidation. After this incubation period, the Fe-20Cr alloy showed sulfidation behavior similar to that when the alloy was not pre-oxidized. The incubation period during sulfidation of the Fe-20Cr-5Al alloy was significantly longer, over 45 h, compared to 2 h for the Al free alloy. Based on the microscopic and gravimetric data a mechanism for sulfidation of these alloys with pre-oxidation has been proposed.

Reduction kinetics of zinc and cadmium sulfides with hydrogen

International Nuclear Information System (INIS)

Turgenev, I.S.; Kabisov, I.Kh.; Zviadadze, G.N.; Vasil'eva, O.Yu.

1985-01-01

Kinetics of reduction processes of zinc sulfide in the temperature range 800-1100 deg C and of cadmium sulfide 600-900 deg C has been stodied. Activation energies and reaction order in terms of hydrogen are calculated. Thermodynamic processes of reduction depend on aggregate state of the metal formed. For vaporous zinc in the temperature range 1050-950 deq C activation energy constitutes 174 kJ/mol, for liquid in the range 900-850 deg - 151 kJ/mol and reaction order in terms of hydrogen is 1.0. For vaporous cadmium in the temperature range 900-700 deg C activation energy constitutes 144 kJ/mol and reaction order in terms of hydrogen is 0.86, for liquid in the range 675-600 deg C 127 kJ/mol and 0.8 respectively. The processes of zinc and cadmium sulfide reduction proceed in kinetic regime and are limited by the rate of chemical reaction

Carbon steel protection in G.S. (Girlder sulfide) plants. CITROSOLV process influence. Pt. 6

International Nuclear Information System (INIS)

Lires, O.A.; Burkart, A.L.; Delfino, C.A.; Rojo, E.A.

1988-01-01

In order to protect carbon steel towers and piping of Girlder sulfide (G.S.) experimental heavy water plants against corrosion produced by the action of aqueous solutions of hydrogen sulfides, a method, previously published, was developed. Carbon steel, exposed to saturated aqueous solutions of hydrogen sulfide, forms iron sulfide scales. In oxygen free solutions evolution of corrosion follows the sequence: mackinawite → cubic ferrous sulfide → troilite → pyrrotite → pyrite. Scales formed by pyrrotite-pyrite or pyrite are the most protective layers (these are obtained at 130 deg C, 2 MPa, for periods of 14 days). CITROSOLV Process (Pfizer) is used to descaling and passivating stainless steel plant's components. This process must be used in mixed (carbon steel - stainless steel) circuits and may cause the formation of magnetite scales over the carbon steel. The influence of magnetite in the pyrrotite-pyrite scales formation is studied in this work. (Author) [es

Structural and Mechanistic Insights into Hemoglobin-catalyzed Hydrogen Sulfide Oxidation and the Fate of Polysulfide Products

Energy Technology Data Exchange (ETDEWEB)

Vitvitsky, Victor; Yadav, Pramod K.; An, Sojin; Seravalli, Javier; Cho, Uhn-Soo; Banerjee, Ruma (Michigan-Med); (UNL)

2017-02-17

Hydrogen sulfide is a cardioprotective signaling molecule but is toxic at elevated concentrations. Red blood cells can synthesize H2S but, lacking organelles, cannot dispose of H2S via the mitochondrial sulfide oxidation pathway. We have recently shown that at high sulfide concentrations, ferric hemoglobin oxidizes H2S to a mixture of thiosulfate and iron-bound polysulfides in which the latter species predominates. Here, we report the crystal structure of human hemoglobin containing low spin ferric sulfide, the first intermediate in heme-catalyzed sulfide oxidation. The structure provides molecular insights into why sulfide is susceptible to oxidation in human hemoglobin but is stabilized against it in HbI, a specialized sulfide-carrying hemoglobin from a mollusk adapted to life in a sulfide-rich environment. We have also captured a second sulfide bound at a postulated ligand entry/exit site in the α-subunit of hemoglobin, which, to the best of our knowledge, represents the first direct evidence for this site being used to access the heme iron. Hydrodisulfide, a postulated intermediate at the junction between thiosulfate and polysulfide formation, coordinates ferric hemoglobin and, in the presence of air, generated thiosulfate. At low sulfide/heme iron ratios, the product distribution between thiosulfate and iron-bound polysulfides was approximately equal. The iron-bound polysulfides were unstable at physiological glutathione concentrations and were reduced with concomitant formation of glutathione persulfide, glutathione disulfide, and H2S. Hence, although polysulfides are unlikely to be stable in the reducing intracellular milieu, glutathione persulfide could serve as a persulfide donor for protein persulfidation, a posttranslational modification by which H2S is postulated to signal.

Slip Zone versus Damage Zone Micromechanics, Arima-Takasuki Tectonic Line, Japan

Science.gov (United States)

White, J. C.; Lin, A.

2017-12-01

The Arima-Takasuki Tectonic Line (ATTL) of southern Honshu, Japan is defined by historically active faults and multiple splays producing M7 earthquakes. The damage zone of the ATTL comprises a broad zone of crushed, comminuted and pulverized granite/rhyolite1,2containing cm-scale slip zones and highly comminuted injection veins. In this presentation, prior work on the ATTL fault rocks is extending to include microstructural characterization by transmission electron microscopy (TEM) from recent trenching of the primary slip zone, as well as secondary slip zones. This is necessary to adequately characterize the extremely fine-grained material (typically less than 1mm) in both damage and core zones. Damage zone material exhibits generally random textures3 whereas slip zones are macroscopically foliated, and compositionally layered, notwithstanding a fairly homogeneous protolith. The latter reflects fluid-rock interaction during both coseismic and interseismic periods. The slip zones are microstructurally heterogeneous at all scales, comprising not only cataclasites and phyllosilicate (clay)-rich gouge zones, but Fe/Mn pellets or clasts that are contained within gouge. These structures appear to have rolled and would suggest rapid recrystallization and/or growth. A central question related to earthquake recurrence along existing faults is the nature of the gouge. In both near-surface exposures and ongoing drilling at depth, "plastic" or "viscous" gouge zones comprise ultra-fine-grained clay-siliciclastic particles that would not necessarily respond in a simple frictional manner. Depending on whether the plastic nature of these slip zones develops during or after slip, subsequent focusing of slip within them could be complicated. 1 Mitchell, T.A., Ben-Zion, Y., Shimamoto, T., 2011. Ear. Planet. Sci. Lett. 308, 284-297. 2 Lin, A., Yamashita, K, Tanaka, M. J., 2013. Struc. Geol. 48, 3-13. 3 White, J.C., Lin, A. 2016. Proc. AGU Fall Mtg., T42-02 San Francisco.

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

Er2S[SiO4]: An erbium sulfide ortho-oxosilicate with unusual sulfide anion coordination

International Nuclear Information System (INIS)

Hartenbach, Ingo; Lauxmann, Petra; Schleid, Thomas

2004-01-01

During the reaction of cadmium sulfide with erbium and sulfur in evacuated silica ampoules pink lath-shaped crystals of Er 2 S[SiO 4 ] occur as by-product which were characterized by X-ray single crystal structure analysis. The title compound crystallizes orthorhombically in the space group Cmce (a = 1070.02(8), b = 1235.48(9), c = 683.64(6) pm) with eight formula units per unit cell. Besides isolated ortho-oxosilicate units [SiO 4 ] 4- , the crystal structure contains two crystallographically independent Er 3+ cations which are both eightfold coordinated by six oxygen and two sulfur atoms. The sulfide anions are surrounded by four erbium cations each in the shape of very distorted tetrahedra. These excentric [SEr 4 ] 10+ tetrahedra build up layers according to 2 ∞ [SEr 4/2 ] 4+ by vertex- and edge-connection. They are piled parallel to (010) and separated by the isolated ortho-oxosilicate tetrahedra. (Abstract Copyright [2004], Wiley Periodicals, Inc.) [de

Hierarchical Nickel Sulfide Coated Halloysite Nanotubes For Efficient Energy Storage

International Nuclear Information System (INIS)

Li, Yanan; Zhou, Jie; Liu, Yun; Tang, Jian; Tang, Weihua

2017-01-01

Highlights: •An integration strategy was presented to construct Ni 3 S 2 based hierarchical composite. •Nanowhisker Ni 3 S 2 were densely integrated onto halloysite nanotubes. •The well-designed electrode exhibits remarkable capacitance and cycling stability. •This strategy provides good reference to electrode materials design for energy storage -- Abstract: Cost-effective and robust energy storage systems have attracted great attention for portable electronic devices. Three-dimensional electrodes can effectively enhance the charge transfer, increase the mechanical stability and thus improve the electrochemical performance upon continuous charge-discharge. The earth abundant halloysite nanotubes (HNTs) have shown immense potential in constructing nanoarchitectural composites. Here, we first demonstrate the development of hybrid composite of nickel sulfide (Ni 3 S 2 ) and HNTs with glucose as binders for efficient energy storage in supercapacitor. The surface sulfhydrylation of HNTs and glucose-assisted hydrothermal reaction are crucial for the preparation of well-structured composite. Due to the synergistic effect between components, the Ni 3 S 2 /HNTs@HS composite electrode delivers a capacity of 450.4C g −1 and high retention of 82.6% over 2000 cycles in three-electrode supercapacitors. Moreover, the Ni 3 S 2 /HNTs@HS//Whatman paper//Ni 3 S 2 /HNTs@HS two-electrode symmetric supercapacitor exhibits a maximum potential window of 1.3 V, with a capacity of 250C g −1 and performance loss of only 18.2% over 2000 cycling at 1 A g −1 . A maximum energy density of 79.6 Wh kg −1 is achieved at a power density of 1.03 kW kg −1 . Such excellent energy storage performance suggests the great potential of Ni 3 S 2 /HNTs@HS for high-efficiency energy storage systems.

β-Cobalt sulfide nanoparticles decorated graphene composite electrodes for high capacity and power supercapacitors

Science.gov (United States)

Qu, Baihua; Chen, Yuejiao; Zhang, Ming; Hu, Lingling; Lei, Danni; Lu, Bingan; Li, Qiuhong; Wang, Yanguo; Chen, Libao; Wang, Taihong

2012-11-01

Electrochemical supercapacitors have drawn much attention because of their high power and reasonably high energy densities. However, their performances still do not reach the demand of energy storage. In this paper β-cobalt sulfide nanoparticles were homogeneously distributed on a highly conductive graphene (CS-G) nanocomposite, which was confirmed by transmission electron microscopy analysis, and exhibit excellent electrochemical performances including extremely high values of specific capacitance (~1535 F g-1) at a current density of 2 A g-1, high-power density (11.98 kW kg-1) at a discharge current density of 40 A g-1 and excellent cyclic stability. The excellent electrochemical performances could be attributed to the graphene nanosheets (GNSs) which could maintain the mechanical integrity. Also the CS-G nanocomposite electrodes have high electrical conductivity. These results indicate that high electronic conductivity of graphene nanocomposite materials is crucial to achieving high power and energy density for supercapacitors.

β-Cobalt sulfide nanoparticles decorated graphene composite electrodes for high capacity and power supercapacitors.

Science.gov (United States)

Qu, Baihua; Chen, Yuejiao; Zhang, Ming; Hu, Lingling; Lei, Danni; Lu, Bingan; Li, Qiuhong; Wang, Yanguo; Chen, Libao; Wang, Taihong

2012-12-21

Electrochemical supercapacitors have drawn much attention because of their high power and reasonably high energy densities. However, their performances still do not reach the demand of energy storage. In this paper β-cobalt sulfide nanoparticles were homogeneously distributed on a highly conductive graphene (CS-G) nanocomposite, which was confirmed by transmission electron microscopy analysis, and exhibit excellent electrochemical performances including extremely high values of specific capacitance (~1535 F g(-1)) at a current density of 2 A g(-1), high-power density (11.98 kW kg(-1)) at a discharge current density of 40 A g(-1) and excellent cyclic stability. The excellent electrochemical performances could be attributed to the graphene nanosheets (GNSs) which could maintain the mechanical integrity. Also the CS-G nanocomposite electrodes have high electrical conductivity. These results indicate that high electronic conductivity of graphene nanocomposite materials is crucial to achieving high power and energy density for supercapacitors.

Supramolecular binding and release of sulfide and hydrosulfide anions in water.

Science.gov (United States)

Vázquez, J; Sindelar, V

2018-06-05

Hydrogen sulfide (H2S) has become an important target for research due to its physiological properties as well as its potential applications in medicine. In this work, supramolecular binding of sulfide (S2-) and hydrosulfide (HS-) anions in water is presented for the first time. Bambusurils were used to slow down the release of these anions in water.

Study of radiation synovectomy using 188Re-sulfide in hemophilic arthritis

International Nuclear Information System (INIS)

Li, P.Y.; Cheng, G.; Jiang, X.F.; Wang, X.F.; Shen, Z.M.; Zhang, Z.H.

2002-01-01

Purpose: Based on results of previous animal studies, the efficacy of 188 Re-sulfide on radiation synovectomy in hemophilia synovitis.was evaluated. Material and Methods: 188 Re-sulfide suspension was produced by dispersion method. 25 hemophilic patients with 30 synovitic joints including 22 knees and 8 ankles received the radiation synovectomy. The stage of synovitic joint was classified by joint score including the pain, stability and range of motion and MR score. The doses of 188 Re-sulfide injected into knee and ankle were determined as 12mCi and 6mCi respectively, according to the depth and curve and the results of our previous animal study. To exam the distribution of 188 Re-sulfide in vivo after the injection, a whole-body scan was taken 24 and 48 hours later to calculate the retention of 188 Re-sulfide in joint by percentage of join counts in whole body. The follow up was take place at 6-12 months after the synovectomy by joint score, MRI score, synovial structure, the times and interval of hemorrhage of the joints. Results: Few patients complained discomfort after the injection such as hurt of the superficial tissues around the injected point and swelling (2 patients,.8%).The symptoms in this two patients continued up to 3 days and gradually decreased in severity. All patients felt relief of the pain and swelling in joints. 90% joints including 20 knees and 7 ankles did not bleed any more during the 3-month term of follow up, 3 joints from 2 patients with intra-article bleeding had hemorrhage in one month after long distance walk. 16%(5/30) of joints including 4 knees and 1 ankles had recurrent hemorrhage in 12 months after the radiation synovectomy. However, their interval of intra-article bleeding was prolonged MRI showed the thick synovium became thin, villi reduced and the joint edema relieved. The retention of 188 Re-sulfide in administrated joint was more than 95% until 48 hours later. No any sign of radioactive distribution was found in bone marrow

Metasomatic Reaction Zones as Monitors of Trace Element Transfer at the Slab-Mantle Interface: the Case of the Hochwart Peridotite (Ulten Zone, Italy)

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Marocchi, M.; Hermann, J.; Bargossi, G. M.; Mair, V.; Morten, L.

2006-12-01

Ultramafic blocks belonging to the Hochwart peridotite outcrop (Ulten Zone, Italian Alps) preserve a series of metasomatic mineral zones generated by infiltration of Si-rich hydrous fluids which occurred at the gneiss- peridotite interface. The age of the high pressure metamorphism for the Hochwart complex has been constrained at 330 Ma (Tumiati et al., 2003, EPSL, 210, 509-526). The country rocks are stromatic gneisses consisting mainly of quartz, K-feldspar, garnet, kyanite, biotite and muscovite. The ultramafic body consists of strongly serpentinized metaperidotites which are exposed as a hectometre-size lens along a steep gully, associated to monomineralic zones that developed at the contact between the peridotite body and the garnet gneiss country rocks. The composition of the metasomatic zones has been investigated in detail and records an order of metasomatic zoning formed by phlogopite-rich to tremolite-anthophyllite-rich rocks going from the host gneiss towards the peridotite. In some cases, the ultramafics fade into the gneisses developing serpentine and talc which has replaced, presumably at lower temperatures, the serpentine matrix and occurs in association with chlorite. Phlogopite aggregates (phlogopitite) with accessory minerals (quartz + zircon + apatite) and metabasic pods (phlogopite and hornblende) also occur. Black tourmaline (schorl-dravite solid solution) has been found for the first time in the contact near the phlogopite zone, suggesting an external addition of elements (boron and fluorine) to the system at high temperature. The formation of the metasomatic zones composed exclusively of hydrous phases must have involved extensive H2O-metasomatism as already documented for the Ulten peridotites. The source for these fluids can be a system of trondhjemitic-pegmatitic dikes cutting the peridotite that would have channelled aqueous fluids into the ultramafic rocks. Whole-rock geochemistry and trace element (LA ICP-MS) composition of hydrous

Composite volcanoes in the south-eastern part of İzmir-Balıkesir Transfer Zone, Western Anatolia, Turkey

Science.gov (United States)

Seghedi, Ioan; Helvacı, Cahit; Pécskay, Zoltan

2015-01-01

During the Early-Middle Miocene (Western Anatolia) several volcanic fields occur along a NE-SW-trending shear zone, known as İzmir-Balıkesir Transfer Zone. This is a deformed crustal-scale sinistral strike-slip fault zone crossing the Bornova flysch and extending along the NW-boundary of the Menderes Massif by accommodating the differential deformation between the Cycladic and Menderes core complexes within the Aegean extensional system. Here we discuss the volcanic activity in Yamanlar and Yuntdağı fields that is closely related to the extensional tectonics of the İzmir-Balıkesir Transfer Zone and in the same time with the episodic core complex denudation of the Menderes Massif. This study documents two composite volcanoes (Yamanlar and Yuntdağı), whose present vent area is strongly eroded and cut by a variety of strike-slip and normal fault systems, the transcurrent NW-SE being the dominant one. The erosional remnants of the vent areas, resembling a shallow crater intrusive complex, illustrate the presence of numerous dykes or variably sized neck-like intrusions and lava flows, typically associated with hydrothermal alteration processes (propylitic and argillic). Such vent areas were observed in both the examined volcanic fields, having ~ 6 km in diameter and being much more eroded toward the south, along the NW-SE fault system. Lava flows and lava domes are sometimes associated with proximal block and ash flow deposits. In the cone-building association part, besides lava flows and remnants of lava domes, rare block and ash and pumice-rich pyroclastic flow deposits, as well as a series of debris-flow deposits, have been observed. The rocks display a porphyritic texture and contain various proportions of plagioclase, clinopyroxene, orthopyroxene, amphibole, rare biotite and corroded quartz. The examined rocks fall at the limit between calc-alkaline to alkaline field, and plot predominantly in high-K andesite and dacite fields and one is rhyolite. The trace

Effect of Ammonium Chloride on the Efficiency with Which Copper Sulfate Activates Marmatite: Change in Solution Composition and Regulation of Surface Composition

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Shengdong Zhang

2018-06-01

Full Text Available Zinc sulfide minerals are the primary choice for zinc extraction and marmatite is one of the two most common zinc sulphide minerals (sphalerite and marmatite, therefore it is of great significance to study and optimize the flotation of marmatite. To improve the activation of copper sulfate on marmatite, a method involving the addition of ammonium chloride is devised. The method has been proven to be an effective way of improving the activation efficiency of copper sulfate towards marmatite under alkaline conditions. The strengthening mechanism was studied using micro-flotation, adsorption test, X-ray photoelectron spectroscopy, and by analyzing changes in solution composition. Flotation test results show that the activation effect of the copper sulfate towards marmatite is enhanced with the addition of ammonium chloride. According to the results of the adsorption measurements and X-ray photoelectron spectroscopy analysis, when the marmatite surface is activated using copper sulfate with added ammonia chloride, it adsorbs more copper sulfide and less copper hydroxide and zinc hydroxide. These changes in surface composition are believed to occur via the following process: NH3(aq promotes the dissolution of zinc hydroxide and then facilitates the conversion of surface copper hydroxide to copper sulfide. In addition, the occurrence of Cu(NH3n2+ can promote the adsorption of copper ions (Cu2+ can be stored as Cu(NH3n2+ via complexation, and then, when the concentration of copper ions decreases, Cu2+ can be released through the decompositionof Cu(NH3n2+. Hence, the copper ion concentration can be maintained and this can facilitate the adsorption of Cu2+ on marmatite. Based on a comprehensive analysis of all our results, we propose that adding ammonium chloride to the copper sulfate changes the solution components (i.e., the presence of NH3(aq and Cu(NH3n2+ and then regulates the surface composition of marmatite. The change in surface composition

Hydrogen sulfide metabolism regulates endothelial solute barrier function

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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.

What do we really know about the role of microorganisms in iron sulfide mineral formation?

Science.gov (United States)

Picard, Aude A.; Gartman, Amy; Girguis, Peter R.

2016-01-01

Iron sulfide mineralization in low-temperature systems is a result of biotic and abiotic processes, though the delineation between these two modes of formation is not always straightforward. Here we review the role of microorganisms in the precipitation of extracellular iron sulfide minerals. We summarize the evidence that links sulfur-metabolizing microorganisms and sulfide minerals in nature and we present a critical overview of laboratory-based studies of the nucleation and growth of iron sulfide minerals in microbial cultures. We discuss whether biologically derived minerals are distinguishable from abiotic minerals, possessing attributes that are uniquely diagnostic of biomineralization. These inquiries have revealed the need for additional thorough, mechanistic and high-resolution studies to understand microbially mediated formation of a variety of sulfide minerals across a range of natural environments.

Remediation of arsenic and lead with nanocrystalline zinc sulfide.

Science.gov (United States)

Piquette, Alan; Cannon, Cody; Apblett, Allen W

2012-07-27

Nanocrystalline (1.7 ± 0.3 nm) zinc sulfide with a specific surface area up to 360 m(2) g(-1) was prepared from the thermal decomposition of a single-source precursor, zinc ethylxanthate. Zinc ethylxanthate decomposes to cubic zinc sulfide upon exposure to temperatures greater than or equal to 125 °C. The resulting zinc sulfide was tested as a water impurity extractant. The target impurities used in this study were As(5+), As(3+), and Pb(2+). The reaction of the nanocrystalline ZnS with Pb(2+) proceeds as a replacement reaction where solid PbS is formed and Zn(2+) is released into the aqueous system. Removal of lead to a level of less than two parts per billion is achievable. The results of a detailed kinetics experiment between the ZnS and Pb(2+) are included in this study. Unlike the instance of lead, both As(5+) and As(3+) adsorb on the surface of the ZnS extractant as opposed to an ion-exchange process. An uptake capacity of > 25 mg g(-1) for the removal of As(5+) is possible. The uptake of As(3+) appears to proceed by a slower process than that of the As(5+) with a capacity of nearly 20 mg g(-1). The nanocrystalline zinc sulfide was extremely successful for the removal of arsenic and lead from simulated oil sand tailing pond water.

Antifoaming materials in G.S. (Girlder sulfide) heavy water plants. Thermical stability. Pt. 2

International Nuclear Information System (INIS)

Delfino, C.A.

1986-01-01

In Girlder sulfide (G.S.) heavy water plants hydrogen sulfide-water systems are inherentely foaming, so the adding of antifoaming materials is of great importance. These may be of high volatility, pyrolizable or chemically unstable in plant operation conditions (water and hydrogen sulfide at 2 MPa, up to 230 deg C). About twenty commercial surfactants were studied from the point of view of their thermical stability. (Author) [es

COMPOSITE MATERIALS BASED ON ZINC SULFIDE AND ZINC OXIDE: STRUCTURAL AND BIOCIDAL PROPERTIES

Directory of Open Access Journals (Sweden)

Sukhodub L.B

2016-12-01

Full Text Available Introduction. The widespread use of drugs with antimicrobial action has led to the formation of microorganism resistance against wide range of antibiotics. One of the approaches to dissolving this problem is the substances modification by inorganic bioactive ions in oder to initiate a controlled reaction in the bone tissues and provision of antimicrobial activity. It is known that ZnO-based materials have a pronounced biocompatibility, they are characterized by high limit strength, absolute mechanical hardness, as well as the ability to withstand the harsh operating conditions. The aim of this work is the study of structural and biocidal properties of composite material based on zinc oxide and zinc sulfide (ZnS-ZnO and its complex with an organic substance - sodium alginate (ZnS-ZnO-Alg for use in biomedical purpose. Materials and methods. For the synthesis of ZnS-ZnO composite 50 ml 0.2M solution zinc nitrate was added to the 50 ml 0.2M thiourea CS (NH ₂ ₂ solution and stirred in a shaker for 60 minutes. The formation of the compound took place when added to a mixture of 25 mas.% solution of ammonia with the subsequent heating at 80 oC for 30 minutes. Synthesis of the metalorganic complex of ZnS-ZnO-Alg was performed by above mentioned procedure, but to the thiourea solution was previously added 1 ml of 3 mas.% solution of sodium alginate under ultrasonic mixing.. For the next research composites were dried or lyophilized. Study of antibacterial activity of the ZnS-ZnO and ZnS-ZnO-Alg particles was carried out with the use of nutrient mediums: Muller Hinton, meat-pepton nutrient (MPN. As the reference cultures were used E. coli ATCC 25922, S. aureus ATCC 25923, S. aureus ATSS 29213, S. aureus ATSS-6538, C albicans ATCC 885-653. Determination of the minimum bactericidal concentration (MBC was carried out by a modified serial diluted method in liquid nutrient broth followed plating on solid Muller Hinton nutrient medium. In addition, the

A subduction wedge origin for Paleoarchean peridotitic diamonds and harzburgites from the Panda kimberlite, Slave craton: evidence from Re-Os isotope systematics

Science.gov (United States)

Westerlund, K. J.; Shirey, S. B.; Richardson, S. H.; Carlson, R. W.; Gurney, J. J.; Harris, J. W.

2006-09-01

An extensive study of peridotitic sulfide inclusion bearing diamonds and their prospective harzburgitic host rocks from the 53 Ma Panda kimberlite pipe, Ekati Mine, NWT Canada, has been undertaken with the Re-Os system to establish their age and petrogenesis. Diamonds with peridotitic sulfide inclusions have poorly aggregated nitrogen (bearing diamonds and indicates residence in the cooler portion of the Slave craton lithospheric mantle. For most of the sulfide inclusions, relatively low Re contents (average 0.457 ppm) and high Os contents (average 339 ppm) lead to extremely low 187Re/188Os, typically << 0.05. An age of 3.52 ± 0.17 Ga (MSWD = 0.46) and a precise initial 187Os/188Os of 0.1093 ± 0.0001 are given by a single regression of 11 inclusions from five diamonds that individually provide coincident internal isochrons. This initial Os isotopic composition is 6% enriched in 187Os over 3.5 Ga chondritic or primitive mantle. Sulfide inclusions with less radiogenic initial Os isotopic compositions reflect isotopic heterogeneity in diamond forming fluids. The harzburgites have even lower initial 187Os/188Os than the sulfide inclusions, some approaching the isotopic composition of 3.5 Ga chondritic mantle. In several cases isotopically distinct sulfides occur in different growth zones of the same diamond. This supports a model where C-O-H-S fluids carrying a radiogenic Os signature were introduced into depleted harzburgite and produced diamonds containing sulfides conforming to the 3.5 Ga isochron. Reaction of this fluid with harzburgite led to diamonds with less radiogenic inclusions while elevating the Os isotope ratios of some harzburgites. Subduction is a viable way of introducing such fluids. This implies a role for subduction in creating early continental nuclei at 3.5 Ga and generating peridotitic diamonds.

A recovery installation for sodium sulfates, thiosulfates and sulfides from waste water resulting from hydrogen sulfide fabrication

International Nuclear Information System (INIS)

Mazilu, Mihai; Costescu, Sanda

2002-01-01

An installation for recovery of sodium sulfate and sulfur suspensions from waste water was conceived. It consists from a preheater, vacuum evaporator and a refrigerating system with drum and scraper. This equipment concentration the solution by eliminating in the first stage the water in the vacuum evaporator. The water resulting at this stage is chemically pure and can be discharged in the sewage sludge system. The concentrated solution is then directed to the refrigerating system with drum and scrapper. Here the sodium sulfates, thiosulfates and sulfides get crystallized onto the drum surface. The resulting aqueous solution to be discharged in the sewage sludge system is previously analyzed as in case of the absent of the recovery installation, but the amount of pollutants will be much lower because sulfates, thiosulfates and sulfides were already recovered as scales from the drum. These solid scales can be used in detergent industry

Effect of ambient hydrogen sulfide on the physical properties of vacuum evaporated thin films of zinc sulfide

Energy Technology Data Exchange (ETDEWEB)

Singh, Beer Pal [Department of Physics, C.C.S. University, Meerut 250004 (India)], E-mail: drbeerpal@gmail.com; Singh, Virendra [Forensic Science Laboratory, Malviya Nagar, New Delhi 110017 (India); Tyagi, R.C.; Sharma, T.P. [Department of Physics, C.C.S. University, Meerut 250004 (India)

2008-02-15

Evaporated thin films of zinc sulfide (ZnS) have been deposited in a low ambient atmosphere of hydrogen sulfide (H{sub 2}S {approx}10{sup -4} Torr). The H{sub 2}S atmosphere was obtained by a controlled thermal decomposition of thiourea [CS(NH{sub 2}){sub 2}] inside the vacuum chamber. It has been observed that at elevated substrates temperature of about 200 deg. C helps eject any sulfur atoms deposited due to thermal decomposition of ZnS during evaporation. The zinc ions promptly recombine with H{sub 2}S to give better stoichiometry of the deposited films. Optical spectroscopy, X-ray diffraction patterns and scanning electron micrographs depict the better crystallites and uniformity of films deposited by this technique. These deposited films were found to be more adherent to the substrates and are pinhole free, which is a very vital factor in device fabrication.