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Dalhem, Krister, Stefan Mattbäck, Anton Boman e Peter Österholm. "A simplified distillation-based sulfur speciation method for sulfidic soil materials". Bulletin of the Geological Society of Finland 93, n. 1 (13 giugno 2021): 19–30. http://dx.doi.org/10.17741/bgsf/93.1.002.
Testo completoAbstract (sommario):
Speciation of inorganic sulfur species, mainly pyrite and metastable iron sulfides by operationally defined methods, is widely used for risk assessment of acid sulfate soils by quantifying the acidity producing elements, as well as for general characterisation of marine sediments and subaqueous soils. “Traditional” sulfur speciation methods commonly use highly specialised glassware which can be cumbersome for the operator, or, require long reaction times which limit the usability of the method. We present a simplified method which has a sufficiently low limit of detection (0.002%) and quantitation (0.006%) required for the analysis of sulfidic sulfur in acid sulfate soil materials. Commercially available sulfide reagents were used for determining reproducibility and the method was assessed on natural sulfidic soil materials, including fine to coarse grained soil materials as well as sulfide bearing peat, with a large variation of metastable sulfide and pyrite content.
2
Halkjær Nielsen, Per. "Sulfur Sources for Hydrogen Sulfide Production in Biofilms from Sewer Systems". Water Science and Technology 23, n. 7-9 (1 aprile 1991): 1265–74. http://dx.doi.org/10.2166/wst.1991.0578.
Testo completoAbstract (sommario):
The relative significance of different inorganic and organic sulfur compounds on the sulfide production in anaerobic biofilms grown on domestic wastewater was investigated. The objective was to improve the understanding of microbial processes in dynamic systems and to evaluate the equations used to predict sulfide formation in pressure mains. Biofilms originally grown on domestic wastewater with sulfate as the only electron acceptor were also able to reduce sulfite and thiosulfate. The bacteria preferred thiosulfate to sulfate if both were present and the sulfide production rates increased with a factor of 1.5. Disproportionation of thiosulfate to equal amounts of sulfide and sulfate was demonstrated to take place in the biofilms but only at low concentrations of organic substrates. Some sulfide production from the organic sulfur compounds cysteine and methionine was observed. The rates were, however, insignificant compared to sulfide production from sulfate reduction in wastewater. Biofilm activity measured as the zero order volume constant (kof) was around 0.18 mg SO4-S cm−3 h−1 at 20 °C. If the biofilms were grown on domestic wastewater enriched with sulfite or thiosulfate, kof increased around two times. The sulfide production rate from both sulfite and thiosulfate was found to be considerably higher than the rate from sulfate in these biofilms. The results were modeled using biofilm kinetics which showed that the presence of sulfite or thiosulfate in the wastewater strongly affected the potential sulfide production and could in some cases be a limiting compound besides organic matter. Knowledge about the presence of sulfur compounds other than sulfate in wastewater, e.g. from industrial sources, may therefore be very important to forecast sulfide buildup in sewer systems.
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Ma, Hong He, Shu Zhong Wang e Lu Zhou. "Sulfur Transformations during Supercritical Water Oxidation of Methanthiol and Thiirane". Advanced Materials Research 610-613 (dicembre 2012): 1377–80. http://dx.doi.org/10.4028/www.scientific.net/amr.610-613.1377.
Testo completoAbstract (sommario):
The oxidation of methanthiol and thiirane in supercritical water was explored by using a tubular-flow reactor system using oxygen as oxidant. No sulfur containing species existed in the gaseous effluent. Sulfide, sulfite and sulfate were detected as the sulfur containing species in the liquid effluent for supercritical water oxidation (SCWO) of methannthiol, while it was determined as thiosulfate, sulfite and sulfate for SCWO of thiirane. When reaction temperature exceeded 873K, the sulfur contained in the methanthiol or thiirane all transformed into the liquid products. Oxidant stoichiometric ratio had little effect on the conversion rate of sulfur but could promoted sulfite converted into sulfate. Sulfide and thiosulfate were determined as the exclusive sulfur containing product arising directly from methanthiol and thiirane, respectively. The transformation pathways of sulfur contained in the methanthiol and thiirane were proposed as methanthiol-sulfide-sulfite-sulfate and thiirane-thiosulfate-sulfite-sulfate, respectively.
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Ma, Hong He, Shu Zhong Wang e Lu Zhou. "Kinetics Behavior and Sulfur Transformations of Iron Sulfide during Supercritical Water Oxiation". Advanced Materials Research 524-527 (maggio 2012): 1939–42. http://dx.doi.org/10.4028/www.scientific.net/amr.524-527.1939.
Testo completoAbstract (sommario):
Oxidation of iron sulfide in supercritical water was investigated in the batch reactor. Iron sulfide was converted in two parallel processes: gasification by water and oxidation by oxygen. Assuming that the reaction order of H2O was 0, the activation energy and pre-exponential factor of the gasification process were determined to be 43kJ mol-1 and 22.4 min-1, correspondingly. It is found that above 773K the oxidation process was limited by the mass transfer of O2 to particles surface. Below 773K, with an assumption of zero order in H2O concentration and first-order reaction in oxygen concentration, the activation energy and pre-exponential factor for the rate of oxidation were estimated as154kJ mol-1 and 1.7×106m3 mol-1 min-1, respectively. With supercritical water oxidation under the experimental conditions, the sulfur-containing components in the product were sulfide, sulfite and sulfate, in which sulfide and sulfate were predominant. It is likely to completely convert the sulfur to the sulfate by supercritical water oxidation using high temperature and long reaction time. The reaction pathway of iron sulfide could be expressed as: iron sulfide → sulfide → sulfite → sulfate.
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Lestari, Eni, Dedy Darnaedi e Safendrri Komara Ragamustari. "ISOLASI DAN IDENTIFIKASI BAKTERI PENGURAI SULFIDA DARI LUMPUR MANGROVE HUTAN LINDUNG ANGKE KAPUK". Borneo Journal of Biology Education (BJBE) 4, n. 1 (14 aprile 2022): 1–7. http://dx.doi.org/10.35334/bjbe.v4i1.2533.
Testo completoAbstract (sommario):
AbstrakMangrove memiliki mikroorganisme salah satunya bakteri. Lumpur mangrove memiliki kandungan hidrogen sulfida. Bakteri aerobik memetabolisme hidrogen sulfida ini menjadi senyawa sulfat. Isolasi menggunakan medium Thiosulfat Mineral Medium. Isolat yang diamati secara makroskopis. Isolat dipilih dari hasil pengamatan mikroskopik, uji katalase dan uji motilitas. Isolat diuji juga kinerja penurunan sulfida. Isolat dengan kinerja penurunan sulfida terbaik dilanjutkan untuk uji sekuensing 16S rRNA. Hasil sekuensing menunjukkan isolat dari lumpur mangrove yang memiliki kinerja penurunan sulfida terbaik dengan nilai 30,58% adalah bakteri spesies Bacillus aryabhattaiKata kunci : mangrove, sulfida,bakteri, aerobik, BacillusAbstractMangroves have a diversity of microorganisms, one of which is bacteria. Mangrove mud contains hydrogen sulfide. Aerobic bacteria metabolize this hydrogen sulfide to sulfate compounds. Isolation used thiosulfate mineral medium. The growing isolates observed macroscopically. Selected isolates from microscopic observation, catalase test and motility test. The isolates also tested for their sulfide reduction performance. The isolates with the best sulfide reduction performance continued for 16S rRNA sequencing assay. The best sulfide reduction performance is 30,58% and the bacteria species based result sequencing is Bacillus aryabhattai Keywords: mangrove, sulfide, bacteria, aerobic, Bacillus
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Wang, Clifford L., Priya D. Maratukulam, Amy M. Lum, Douglas S. Clark e J. D. Keasling. "Metabolic Engineering of an Aerobic Sulfate Reduction Pathway and Its Application to Precipitation of Cadmium on the Cell Surface". Applied and Environmental Microbiology 66, n. 10 (1 ottobre 2000): 4497–502. http://dx.doi.org/10.1128/aem.66.10.4497-4502.2000.
Testo completoAbstract (sommario):
ABSTRACT The conversion of sulfate to an excess of free sulfide requires stringent reductive conditions. Dissimilatory sulfate reduction is used in nature by sulfate-reducing bacteria for respiration and results in the conversion of sulfate to sulfide. However, this dissimilatory sulfate reduction pathway is inhibited by oxygen and is thus limited to anaerobic environments. As an alternative, we have metabolically engineered a novel aerobic sulfate reduction pathway for the secretion of sulfides. The assimilatory sulfate reduction pathway was redirected to overproduce cysteine, and excess cysteine was converted to sulfide by cysteine desulfhydrase. As a potential application for this pathway, a bacterium was engineered with this pathway and was used to aerobically precipitate cadmium as cadmium sulfide, which was deposited on the cell surface. To maximize sulfide production and cadmium precipitation, the production of cysteine desulfhydrase was modulated to achieve an optimal balance between the production and degradation of cysteine.
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Pellerin, André, Gilad Antler, Simon Agner Holm, Alyssa J. Findlay, Peter W. Crockford, Alexandra V. Turchyn, Bo Barker Jørgensen e Kai Finster. "Large sulfur isotope fractionation by bacterial sulfide oxidation". Science Advances 5, n. 7 (luglio 2019): eaaw1480. http://dx.doi.org/10.1126/sciadv.aaw1480.
Testo completoAbstract (sommario):
A sulfide-oxidizing microorganism, Desulfurivibrio alkaliphilus (DA), generates a consistent enrichment of sulfur-34 (34S) in the produced sulfate of +12.5 per mil or greater. This observation challenges the general consensus that the microbial oxidation of sulfide does not result in large 34S enrichments and suggests that sedimentary sulfides and sulfates may be influenced by metabolic activity associated with sulfide oxidation. Since the DA-type sulfide oxidation pathway is ubiquitous in sediments, in the modern environment, and throughout Earth history, the enrichments and depletions in 34S in sediments may be the combined result of three microbial metabolisms: microbial sulfate reduction, the disproportionation of external sulfur intermediates, and microbial sulfide oxidation.
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Jayaranjan, Madawala Liyanage Duminda, e Ajit P. Annachhatre. "Precipitation of heavy metals from coal ash leachate using biogenic hydrogen sulfide generated from FGD gypsum". Water Science and Technology 67, n. 2 (1 gennaio 2013): 311–18. http://dx.doi.org/10.2166/wst.2012.546.
Testo completoAbstract (sommario):
Investigations were undertaken to utilize flue gas desulfurization (FGD) gypsum for the treatment of leachate from the coal ash (CA) dump sites. Bench-scale investigations consisted of three main steps namely hydrogen sulfide (H2S) production by sulfate reducing bacteria (SRB) using sulfate from solubilized FGD gypsum as the electron acceptor, followed by leaching of heavy metals (HMs) from coal bottom ash (CBA) and subsequent precipitation of HMs using biologically produced sulfide. Leaching tests of CBA carried out at acidic pH revealed the existence of several HMs such as Cd, Cr, Hg, Pb, Mn, Cu, Ni and Zn. Molasses was used as the electron donor for the biological sulfate reduction (BSR) process which produced sulfide rich effluent with concentration up to 150 mg/L. Sulfide rich effluent from the sulfate reduction process was used to precipitate HMs as metal sulfides from CBA leachate. HM removal in the range from 40 to 100% was obtained through sulfide precipitation.
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Borzenko, Svetlana. "Geochemical transformations of sulfur in salt lakes (Transbaikalia)". E3S Web of Conferences 411 (2023): 02009. http://dx.doi.org/10.1051/e3sconf/202341102009.
Testo completoAbstract (sommario):
The water column in brackish and saline lakes hosts various forms of sulfur including sulfide (hydrosulfide), elemental, thiosulfate, and sulfate sulfur. The unequal distribution of these reduced sulfur species indicates the presence of two opposing processes - sulfate reduction and oxidation of newly formed hydrogen sulfide. The scale of these processes varies among lakes, resulting in differing proportions of reduced sulfur forms. The bacterial reduction of sulfate ions is confirmed by a significant separation of sulfur isotopes into sulfide and sulfate ions, with the lighter isotope accumulating in the former and heavier isotope in the latter. In most soda, chloride, brackish, and salt lakes, sulfate reduction is the principal process responsible for relatively low sulfate ion content. Additionally, the presence of an oxidizing environment and sulfides in host rocks provide additional sources for sulfates, leading to the formation of sulfate-type lakes. The formation of specific types and subtypes of brackish and salt lakes is determined by processes such as water evaporation, dissolution of aluminosilicates, sulfate reduction, and oxidation of sulfides. The dominance of these processes contributes to the geochemical diversity of lakes.
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Lamontagne, S., W. S. Hicks, R. W. Fitzpatrick e S. Rogers. "Sulfidic materials in dryland river wetlands". Marine and Freshwater Research 57, n. 8 (2006): 775. http://dx.doi.org/10.1071/mf06057.
Testo completoAbstract (sommario):
Due to a combination of river regulation, dryland salinity and irrigation return, lower River Murray floodplains (Australia) and associated wetlands are undergoing salinisation. It was hypothesised that salinisation would provide suitable conditions for the accumulation of sulfidic materials (soils and sediments enriched in sulfides, such as pyrite) in these wetlands. A survey of nine floodplain wetlands representing a salinity gradient from fresh to hypersaline determined that surface sediment sulfide concentrations varied from <0.05% to ~1%. Saline and permanently flooded wetlands tended to have greater sulfide concentrations than freshwater ones or those with more regular wetting–drying regimes. The acidification risk associated with the sulfidic materials was evaluated using field peroxide oxidations tests and laboratory measurements of net acid generation potential. Although sulfide concentration was elevated in many wetlands, the acidification risk was low because of elevated carbonate concentration (up to 30% as CaCO3) in the sediments. One exception was Bottle Bend Lagoon (New South Wales), which had acidified during a draw-down event in 2002 and was found to have both actual and potential acid sulfate soils at the time of the survey (2003). Potential acid sulfate soils also occurred locally in the hypersaline Loveday Disposal Basin. The other environmental risks associated with sulfidic materials could not be reliably evaluated because no guideline exists to assess them. These include the deoxygenation risk following sediment resuspension and the generation of foul odours during drying events. The remediation of wetland salinity in the Murray–Darling Basin will require that the risks associated with disturbing sulfidic materials during management actions be evaluated.
11
Wilkin, Richard T., e David A. Rogers. "Nickel sulfide formation at low temperature: initial precipitates, solubility and transformation products". Environmental Chemistry 7, n. 6 (2010): 514. http://dx.doi.org/10.1071/en10076.
Testo completoAbstract (sommario):
Environmental context Remediation technologies often rely on manipulation of redox conditions or natural redox processes to favour microbial sulfate-reduction and mineral sulfide formation for treatment of inorganic contaminants in groundwater, including nickel. However, few data are available on the structural properties, solubility and mineral transformation processes involving nickel sulfides. These data are needed in order to constrain the long term performance of groundwater remediation efforts. Abstract The formation of nickel sulfides has been examined experimentally over the temperature range from 25 to 60°C. At all conditions studied, hexagonal (α-NiS) was the initial precipitate from solution containing Ni2+ and dissolved sulfide. Freshly precipitated nickel sulfide possesses significant residual Ni–O coordination as revealed by X-ray absorption spectroscopy. With progressive aging, residual Ni–O coordination is replaced by Ni–S coordination. The formation of millerite (β-NiS, rhombohedral) was not detected in any of the synthesis experiments. In the presence of elemental sulfur, hexagonal NiS converted to polydymite (Ni3S4) and vaesite (NiS2). Thus, conversion of nickel monosulfide to thiospinel and disulfide structures appears to be redox dependent, analogous to aging and transformation processes of iron sulfides. In the absence of elemental sulfur or with only hydrogen sulfide or bisulfide present, transformation of hexagonal NiS was not observed after 1680 h at 60°C. Low-pH solubility experiments yielded a solubility product for hexagonal NiS of log Ks0 = –2.69 ± 0.26. Solubility data at pH > 3 suggest that Ni–bisulfide complexation is important in controlling the solubility of Ni in sulfidic solutions.
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Thériault, Robert D., Sarah-Jane Barnes e Mark J. Severson. "The influence of country-rock assimilation and silicate to sulfide ratios (R factor) on the genesis of the Dunka Road Cu – Ni – platinum-group element deposit, Duluth Complex, Minnesota". Canadian Journal of Earth Sciences 34, n. 4 (1 aprile 1997): 375–89. http://dx.doi.org/10.1139/e17-033.
Testo completoAbstract (sommario):
The Dunka Road deposit is one of several Cu – Ni – platinum-group element (PGE) sulfide occurrences found along the northwestern margin of the Duluth Complex, where the host troctolitic rocks are in contact with metasedimentary rocks of the Animikie Group. Magma contamination through assimilation of sulfidic argillaceous country rocks is generally recognized as having played a key role in the genesis of the mineralization. Three main types of disseminated sulfide mineralization have been identified within the Dunka Road deposit: (i) norite-hosted sulfides, (ii) troctolite-hosted sulfides, and (iii) PGE-rich sulfide horizons. The norite-hosted sulfides are found either adjacent to country-rock xenoliths or near the basal contact. The troctolite-hosted sulfides form the bulk of the deposit, and occur throughout the lower 250 m of the intrusion. The PGE-rich sulfide horizons are typically localized directly beneath ultramafic layers. The composition of the different types of sulfide occurrences is modelled using Cu/Pd ratios. It is shown that each type results from the interplay of two main parameters, namely the degree of magma contamination and the silicate magma to sulfide melt ratio (R factor). The norite-hosted sulfides formed at low R factors and high degrees of contamination, as expressed by their PGE-depleted nature, low Se/S ratios, and elevated content in pyrrhotite and arsenide minerals. The troctolite-hosted sulfides formed at moderate R factors and small degrees of contamination, as shown by their moderate PGE content and mantle-like Se/S ratios. Finally, the PGE-rich sulfide horizons are modelled using elevated R factors from an uncontaminated parental magma, which is substantiated by their elevated noble metal content and Se/S ratios, and low pyrrhotite to precious metal sulfide ratio.
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Kurmangalieva, Anna I., Lyubov' A. Anikanova, Ol'ga V. Volkova, Alexandr I. Kudyakov, Yurij S. Sarkisov e Yurij A. Abzaev. "ACTIVATION OF HARDENING PROCESSES OF FLUOROGYPSUM COMPOSITIONS BY CHEMICAL ADDITIVES OF SODIUM SALTS". IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 63, n. 8 (24 giugno 2020): 73–80. http://dx.doi.org/10.6060/ivkkt.20206308.6137.
Testo completoAbstract (sommario):
The article is devoted to modifications of fluorogypsum compositions by chemical additives of sodium salts in the form of sulfate, sulfite and sodium sulfide, as well as their combined effect on the kinetics of structure formation processes. Technological, ecological and technical aspects of utilization of fluorogypsum compositions activated by additives were investigated. Experiments have shown that an up to 3% increase in the amount of sodium sulfite additive leads to an increase in the compressive strength of samples at early stages of hardening (up to 14 days), whereas utilization of sodium sulfate additive forms a crystallization structure at later stages. Therefore, it is rational to combine sulfate and sodium sulfite additives in an amount not exceeding 3% of the binder’s weight. The binder hardening structure formation with sodium sulfide addition at early stages results in production of additional structure-forming substances such as calcium sulfide. The mechanism of differentiated application of individual sulfate and sodium sulfite additives allowed to suggest that combined sulfate and sulfite additives utilization seems to be the most rational decision, due to the fact that it is not a mere individual additives’ combination, but a buffer mixture, which means that the mechanism of such mixtures influence will be subject to the buffer action. The system will maintain a strictly defined pH range constancy, which determines stability of new growths, forming the hardening structure. However, using sodium sulfide as an additive and studying its impact on fluoroanhydrate compositions structure formation in both individual and combined with sodium sulfite and sodium sulfate forms appears to be as much reasonable. The combined Na2SO3-Na2SO4 additive activates hardening processes both at early and late stages. At the same time, columnar structures growing from the center to the periphery are formed, as indicated by electron-microscopic studies. Their growth stems from concentration gradient of SO42-- and SO32-- ions, which is in complete agreement with the other research data and is typical for both metal melts and cement systems solidification process.
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Miura, Yasuyuki, Yusuke Matsushita e Paul R. Haddad. "Stabilization of sulfide and sulfite and ion-pair chromatography of mixtures of sulfide, sulfite, sulfate and thiosulfate". Journal of Chromatography A 1085, n. 1 (agosto 2005): 47–53. http://dx.doi.org/10.1016/j.chroma.2005.02.010.
Testo completo
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Beschkov, Venko N., Elena N. Razkazova-Velkova, Martin S. Martinov e Stefan M. Stefanov. "Performance of Sulfide-Driven Fuel Cell Aerated by Venturi Tube Ejector". Catalysts 11, n. 6 (30 maggio 2021): 694. http://dx.doi.org/10.3390/catal11060694.
Testo completoAbstract (sommario):
Hydrogen sulfide is frequently met in natural waters, like mineral springs, but mostly it is found in marine water with low renewal rate. The Black Sea has extremely high hydrogen sulfide content. It can be utilized in different ways, but the most promising one is direct conversion into electricity. This result can be attained by a sulfide-driven fuel cell (SDFC), converting sulfide to sulfate thus releasing electric energy up to 24 GJ/t. One of the most important problems is the mass transfer limitation on oxygen transfer in the cathode space of the fuel cell. This problem can be solved using a gas diffusion electrode or highly efficient saturation by oxygen in an ejector of the Venturi tube type. This work presents experimental data in laboratory-scale SDFC for sulfide conversion into sulfate, sulfite and polysulfide releasing different amounts of electric energy. Two types of aeration are tested: direct air blow and Venturi-tube ejector. Besides pure graphite, two catalysts, i.e., cobalt spinel and zirconia-doped graphite were tested as anodes. Experiments were carried out at initial sulfide concentrations from 50 to 300 mg/L. Sulfate, sulfite and thiosulfate ions were detected in the outlet solutions from the fuel cell. The electrochemical results show good agreement with the chemical analyses. Most of the results show attained high efficiencies of the fuel cell, i.e., up to 80%. The practical applications of this method can be extended for other purposes, like treatment of polluted water together with utilization as energy.
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Rohwerder, Thore, e Wolfgang Sand. "The sulfane sulfur of persulfides is the actual substrate of the sulfur-oxidizing enzymes from Acidithiobacillus and Acidiphilium spp." Microbiology 149, n. 7 (1 luglio 2003): 1699–710. http://dx.doi.org/10.1099/mic.0.26212-0.
Testo completoAbstract (sommario):
To identify the actual substrate of the glutathione-dependent sulfur dioxygenase (EC 1.13.11.18) elemental sulfur oxidation of the meso-acidophilic Acidithiobacillus thiooxidans strains DSM 504 and K6, Acidithiobacillus ferrooxidans strain R1 and Acidiphilium acidophilum DSM 700 was analysed. Extraordinarily high specific sulfur dioxygenase activities up to 460 nmol min−1 (mg protein)−1 were found in crude extracts. All cell-free systems oxidized elemental sulfur only via glutathione persulfide (GSSH), a non-enzymic reaction product from glutathione (GSH) and elemental sulfur. Thus, GSH plays a catalytic role in elemental sulfur activation, but is not consumed during enzymic sulfane sulfur oxidation. Sulfite is the first product of sulfur dioxygenase activity; it further reacted non-enzymically to sulfate, thiosulfate or glutathione S-sulfonate (). Free sulfide was not oxidized by the sulfur dioxygenase. Persulfide as sulfur donor could not be replaced by other sulfane-sulfur-containing compounds (thiosulfate, polythionates, bisorganyl-polysulfanes or monoarylthiosulfonates). The oxidation of H2S by the dioxygenase required GSSG, i.e. the disulfide of GSH, which reacted non-enzymically with sulfide to give GSSH prior to enzymic oxidation. On the basis of these results and previous findings a biochemical model for elemental sulfur and sulfide oxidation in Acidithiobacillus and Acidiphilium spp. is proposed.
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Straub, Kristina L., e Bernhard Schink. "Ferrihydrite-Dependent Growth of Sulfurospirillum deleyianum through Electron Transfer via Sulfur Cycling". Applied and Environmental Microbiology 70, n. 10 (ottobre 2004): 5744–49. http://dx.doi.org/10.1128/aem.70.10.5744-5749.2004.
Testo completoAbstract (sommario):
ABSTRACT Observations in enrichment cultures of ferric iron-reducing bacteria indicated that ferrihydrite was reduced to ferrous iron minerals via sulfur cycling with sulfide as the reductant. Ferric iron reduction via sulfur cycling was investigated in more detail with Sulfurospirillum deleyianum, which can utilize sulfur or thiosulfate as an electron acceptor. In the presence of cysteine (0.5 or 2 mM) as the sole sulfur source, no (microbial) reduction of ferrihydrite or ferric citrate was observed, indicating that S. deleyianum is unable to use ferric iron as an immediate electron acceptor. However, with thiosulfate at a low concentration (0.05 mM), growth with ferrihydrite (6 mM) was possible and sulfur was cycled up to 60 times. Also, spatially distant ferrihydrite in agar cultures was reduced via diffusible sulfur species. Due to the low concentrations of thiosulfate, S. deleyianum produced only small amounts of sulfide. Obviously, sulfide delivered electrons to ferrihydrite with no or only little precipitation of black iron sulfides. Ferrous iron and oxidized sulfur species were produced instead, and the latter served again as the electron acceptor. These oxidized sulfur species have not yet been identified. However, sulfate and sulfite cannot be major products of ferrihydrite-dependent sulfide oxidation, since neither compound can serve as an electron acceptor for S. deleyianum. Instead, sulfur (elemental S or polysulfides) and/or thiosulfate as oxidized products could complete a sulfur cycle-mediated reduction of ferrihydrite.
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Berg, Jasmine S., Anne Schwedt, Anne-Christin Kreutzmann, Marcel M. M. Kuypers e Jana Milucka. "Polysulfides as Intermediates in the Oxidation of Sulfide to Sulfate by Beggiatoa spp." Applied and Environmental Microbiology 80, n. 2 (8 novembre 2013): 629–36. http://dx.doi.org/10.1128/aem.02852-13.
Testo completoAbstract (sommario):
ABSTRACTZero-valent sulfur is a key intermediate in the microbial oxidation of sulfide to sulfate. Many sulfide-oxidizing bacteria produce and store large amounts of sulfur intra- or extracellularly. It is still not understood how the stored sulfur is metabolized, as the most stable form of S0under standard biological conditions, orthorhombic α-sulfur, is most likely inaccessible to bacterial enzymes. Here we analyzed the speciation of sulfur in single cells of living sulfide-oxidizing bacteria via Raman spectroscopy. Our results showed that under various ecological and physiological conditions, all three investigatedBeggiatoastrains stored sulfur as a combination of cyclooctasulfur (S8) and inorganic polysulfides (Sn2−). Linear sulfur chains were detected during both the oxidation and reduction of stored sulfur, suggesting that Sn2−species represent a universal pool of bioavailable sulfur. Formation of polysulfides due to the cleavage of sulfur rings could occur biologically by thiol-containing enzymes or chemically by the strong nucleophile HS−asBeggiatoamigrates vertically between oxic and sulfidic zones in the environment. MostBeggiatoaspp. thus far studied can oxidize sulfur further to sulfate. Our results suggest that the ratio of produced sulfur and sulfate varies depending on the sulfide flux. Almost all of the sulfide was oxidized directly to sulfate under low-sulfide-flux conditions, whereas only 50% was oxidized to sulfate under high-sulfide-flux conditions leading to S0deposition. With Raman spectroscopy we could show that sulfate accumulated inBeggiatoafilaments, reaching intracellular concentrations of 0.72 to 1.73 M.
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Kushkevych, Ivan V. "Molecular Cloning cysK Gene from Escherichia coli Genome, Transferring in the Intestinal Sulfate-Reducing Bacteria and the Expression Analysis of O-acetylserine(thiol)lyase". Microbes and Health 4, n. 1 (9 dicembre 2016): 19–24. http://dx.doi.org/10.3329/mh.v4i1.23089.
Testo completoAbstract (sommario):
Sulfate-reducing bacteria produce hydrogen sulfide which is toxic and carcinogenic for intestinal epithelial cells and can cause the development of the inflammatory bowel disease and ulcerative colitis in the humans and animals. Enzyme O-acetylserine(thiol)lyase, localized in Escherichia coli genome, use sulfide as substrate in the cysteine synthesis pathway. In this paper, the molecular cloning cysK gene from E. coli, its genetic transferring in the intestinal sulfate-reducing bacterium Desulfovibrio piger Vib-7 and the expression analysis of the enzyme was studied. Cysteine synthesis from hydrogen sulfide as substrate in the D. piger Vib-7 strain at the first time was demonstrated and characterized. The bacterial growth, sulfate and lactate consumption, accumulation of sulfide, acetate and cysteine synthesis in both D. piger Vib-7 wild-type and mutant-type were tested. The mutant-strain consumed much faster sulfate and lactate producing cysteine in the cultivation medium. The expression of the cysK gene in the mutant-type was studied by the formation of the final reaction product (cysteine) and the activity of O-acetylserine(thiol)lyase enzyme. Cysteine level was directly proportional to consumption of sulfate in the mutant-type and accumulation of sulfide in the wild-type. The D. piger Vib-7 mutant-type completely used sulfate the 48th hour of cultivation, thereafter additional sulfite and sulfide doses from the medium were also consumed and converted to cysteine. The obtained genetically constructed mutant strain bacterium D. piger Vib-7 for therapeutic strategy could be applied as a probiotic substance for subjects with inflammatory bowel disease and ulcerative colitis. This strain can compete with other intestinal sulfate-reducing bacteria, actively growth consuming sulfate and lactate much faster, and converting the toxic sulfide to untoxic cysteine in the gut.Microbes and Health, January 2015. 4(1): 19-24
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Beschkov, Venko, Elena Razkazova-Velkova, Martin Martinov e Stefan Stefanov. "Electricity Production from Marine Water by Sulfide-Driven Fuel Cell". Applied Sciences 8, n. 10 (15 ottobre 2018): 1926. http://dx.doi.org/10.3390/app8101926.
Testo completoAbstract (sommario):
While there is a universal trend to replace fossil fuels at least partially, renewable fuels seem to impose new solutions. Hydrogen sulfide, typical for closed water ponds such as the Black Sea, seems to offer one namely, a new sulfide-driven fuel cell providing for exchange of OH− anions across the membrane by use of hydrogen sulfide in natural marine water. When tested in batch and continuous operation modes, this solution showed that the initial sulfide concentration needed to achieve results of practical value was within 200 to 300 mg dm−3. The predominating final products of the energy production process were sulfite and sulfate ions. Very low overpotentials and mass transfer resistances were observed. The mass balance and the electrochemical parameters showed about 30% efficiency in sulfate ions as the final product. Efforts should be made to enhance sulfide to sulfate conversion. The observed current and power density were comparable and even better than some of the results so far reported for similar systems. Three types of ion exchange membranes were tested. Comparison of their ion conductivity to literature data shows good performance. At higher initial sulfide concentrations polysulfides and thio-compounds were formed with considerably low current yield.
21
Jones, Alison M., e Roger Knowles. "Sulfide alleviation of acetylene inhibition of nitrous oxide reduction by Flexibacter Canadensis". Canadian Journal of Microbiology 38, n. 2 (1 febbraio 1992): 143–48. http://dx.doi.org/10.1139/m92-023.
Testo completoAbstract (sommario):
The role of sulfide in the relief of acetylene inhibition of nitrous oxide reduction by Flexibacter canadensis was studied. In this organism, the reversal of acetylene inhibition of nitrous oxide reduction is correlated with a 90% decrease in the dissolved sulfide concentration. The fate of this sulfide is not known, since there was no concomitant increase in acid-soluble sulfide and volatile sulfur compounds were not detectable by flame photometric gas chromatography. Of the other sulfur-containing compounds tested (sulfate, sulfite, thiosulfate, cysteine, methionine, dithionite, dithionate, and glutathione), only cysteine relieved the acetylene block of nitrous oxide reduction by F. canadensis. Under similar experimental conditions, other denitrifiers tested (Azospirillum brasilense, Pseudomonas stutzeri, and a Flavobacterium isolate) failed to reduce nitrous oxide in the presence of sulfide and an inhibitory concentration of acetylene. It is concluded that both biological and abiological factors contribute to the sulfide relief of acetylene inhibition of nitrous oxide by pure cultures of F. canadensis. Key words: denitrification, nitrous oxide, acetylene, sulfide, Flexibacter canadensis.
22
Marion, G. M., J. S. Kargel, J. K. Crowley e D. C. Catling. "Sulfite–sulfide–sulfate–carbonate equilibria with applications to Mars". Icarus 225, n. 1 (luglio 2013): 342–51. http://dx.doi.org/10.1016/j.icarus.2013.02.035.
Testo completo
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Al-Tamir, Mus’ab A., Abdulah I. Al-Haialy e Laith A. Al-Anaz. "Sulfide Removal From The Sulfide Spring". Tikrit Journal of Engineering Sciences 14, n. 2 (30 giugno 2007): 80–96. http://dx.doi.org/10.25130/tjes.14.2.08.
Testo completoAbstract (sommario):
In this study ferrous sulfate had been used as an oxidant for removing the sulfide from water samples taken from sulfide spring in Hamam al-alil south of the Mosul city. The study revealed that ferrous sulfate is efficient in removing sulfide in dose not to exceed to 200mg/l with an efficiency of 77%, also adding of Bentonite clay with ferrous sulfate in a dose of 150mg/l and eliminate the black color due to addition of ferrous sulfate, However; Bentonite clay is inefficient in removing sulfide from the water with dose more than 300mg/l, also the study revealed that the use of Bentonite clay alone or with ferrous sulfate reduce the turbidity of treated water with efficiency more than 89%.
24
Zhang, Ya Hui, Xi Cheng e Qing Wang. "A Low Temperature Precursor Sulfuration Route to Metal Sulfides Nanomaterials". Advanced Materials Research 148-149 (ottobre 2010): 1404–7. http://dx.doi.org/10.4028/www.scientific.net/amr.148-149.1404.
Testo completoAbstract (sommario):
A low-temperature precursor sulfuration route has been established to prepare metal sulfides with different nanostructures during the synthesis of nickel sulfide. The advantages of the low-temperature precursor sulfuration route were testified by the synthesis of different metal sulfides ( lead sulfide, zinc sulfide and cobalt sulfide). It offers a novel path to the preparation of other metal sulfides.
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Lin, Vivian S., Wei Chen, Ming Xian e Christopher J. Chang. "Chemical probes for molecular imaging and detection of hydrogen sulfide and reactive sulfur species in biological systems". Chemical Society Reviews 44, n. 14 (2015): 4596–618. http://dx.doi.org/10.1039/c4cs00298a.
Testo completoAbstract (sommario):
This review highlights progress in the development of molecular probes for live cell imaging of hydrogen sulfide and other reactive sulfur species, including sulfite, bisulfite, sulfane sulfur species, and S-nitrosothiols.
26
Nenkova, Sanchi, Peter Velev, Mirela Dragnevska, Diyana Nikolova e Kiril Dimitrov. "Lignocellulose nanocomposite containing copper sulfide". BioResources 6, n. 3 (6 maggio 2011): 2356–65. http://dx.doi.org/10.15376/biores.6.3.2356-2365.
Testo completoAbstract (sommario):
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.
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Saputra, Beny, Agus Sutanto, Mia Cholvistaria, Suprayitno Suprayitno e Nala Rahmawati. "IDENTIFIKASI BAKTERI PEREDUKSI SULFAT PADA KAWAH AIR PANAS NIRWANA SUOH LAMPUNG BARAT". BIOLOVA 2, n. 2 (30 agosto 2021): 122–27. http://dx.doi.org/10.24127/biolova.v2i2.1089.
Testo completoAbstract (sommario):
Abstrak: Bakteri pereduksi sulfat atau Sulfate-reducing bacteria (SRB) adalah jenis bakteri obligat anaerob kemolitrotof memanfaatkan donor electron H2. Kemampuan SRB mereduksi sulfat menjadi sulfida mampu mengendapkan logam toksik meliputi Cd, Cu, dan Zn sebagai logam sulfida. SRB memerlukan substrat organik seperti asam piruvat yang dihasilkan oleh aktivitas anaerob lainnya. Mekanisme SRB dalam melakukan reduksi sulfat, sulfat digunakan sebagai sumber energi sebagai akseptor elektron dan menggunakan sumber karbon (C) sebagai donor elekton dalam metabolisme dan bahan penyusun sel. Pada kondisi anaerob bahan organik akan berperan sebagai donor elektron. Pembentukan senyawa sulfida melalui proses reduksi yang ditandai oleh penambahan elektron dari bahan organik yang menyebabkan turunnya konsentrasi sulfat dan naiknya pH lingkungan. SRB pada kawah air panas nirwana ini hidup secara anaerob pada suhu lingkungan 600C - 1000C dengan pH 7,4 tingkat kekeruhan air cukup keruh dan kandungan air yang mengandung blerang dengan indikator bau seperti telur busuk dan lingkungan sekitar terdiri dari sedimen batu kapur.
Abstract : Sulfate-reducing bacteria (BPS) is a type of chemolithotroph obligate anaerobic bacteria that utilize H2 electron donors. The ability of BPS to reduce sulfate to sulfide is able to precipitate toxic metals including Cd, Cu, and Zn as metal sulfides. BPS requires organic substrates such as pyruvic acid which is produced by other anaerobic activities. The BPS mechanism in reducing sulfate, sulfate is used as an energy source as an electron acceptor and uses a carbon source (C) as an electron donor in metabolism and cell building material. Under anaerobic conditions, organic matter will act as an electron donor. The formation of sulfide compounds through a reduction process is characterized by the addition of electrons from organic matter which causes a decrease in sulfate concentration and an increase in environmental pH. BPS in this nirvana hot spring crater lives anaerobically at an environmental temperature of 600C - 1000C with a pH of 7.4 the level of turbidity of the water is quite cloudy and the water content contains sulfur with an indicator of smell like rotten eggs and the surrounding environment consists of limestone sediments
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Sethurajan, Manivannan, e Eric D. van Hullebusch. "Leaching and Selective Recovery of Cu from Printed Circuit Boards". Metals 9, n. 10 (24 settembre 2019): 1034. http://dx.doi.org/10.3390/met9101034.
Testo completoAbstract (sommario):
Printed circuit boards (PCBs), a typical end-of-life electronic waste, were collected from an E-waste recycling company located in the Netherlands. Cu and precious metal concentration analyses of the powdered PCBs confirm that the PCBs are multimetallic in nature, rich, but contain high concentrations of Cu, Au, Ag, Pd, and Pt. Ferric sulfate concentration (100 mM), agitation speed (300 rpm), temperature (20 °C), and solid-to-liquid ratio (10 g·L−1) were found to be the optimum conditions for the maximum leaching of Cu from PCBs. The ferric sulfate leachates were further examined for selective recovery of Cu as copper sulfides. The important process variables of sulfide precipitation, such as lixiviant concentration and sulfide dosage were investigated and optimized 100 ppm of ferric sulfate and (copper:sulfide) 1:3 molar ratio, respectively. Over 95% of the dissolved Cu (from the multimetallic leachates) was selectively precipitated as copper sulfide under optimum conditions. The characterization of the copper sulfide precipitates by SEM-EDS analyses showed that the precipitates mainly consist of Cu and S. PCBs can thus be seen as a potential secondary resource for copper.
29
Mo, Shuming, Jinhui Li, Bin Li, Muhammad Kashif, Shiqing Nie, Jianping Liao, Guijiao Su, Qiong Jiang, Bing Yan e Chengjian Jiang. "L-Cysteine Synthase Enhanced Sulfide Biotransformation in Subtropical Marine Mangrove Sediments as Revealed by Metagenomics Analysis". Water 13, n. 21 (1 novembre 2021): 3053. http://dx.doi.org/10.3390/w13213053.
Testo completoAbstract (sommario):
High sulfides concentrations can be poisonous to environment because of anthropogenic waste production or natural occurrences. How to elucidate the biological transformation mechanisms of sulfide pollutants in the subtropical marine mangrove ecosystem has gained increased interest. Thus, in the present study, the sulfide biotransformation in subtropical mangroves ecosystem was accurately evaluated using metagenomic sequencing and quantitative polymerase chain reaction analysis. Most abundant genes were related to the organic sulfur transformation. Furthermore, an ecological model of sulfide conversion was constructed. Total phosphorus was the dominant environmental factor that drove the sulfur cycle and microbial communities. We compared mangrove and non-mangrove soils and found that the former enhanced metabolism that was related to sulfate reduction when compared to the latter. Total organic carbon, total organic nitrogen, iron, and available sulfur were the key environmental factors that effectively influenced the dissimilatory sulfate reduction. The taxonomic assignment of dissimilatory sulfate-reducing genes revealed that Desulfobacterales and Chromatiales were mainly responsible for sulfate reduction. Chromatiales were most sensitive to environmental factors. The high abundance of cysE and cysK could contribute to the coping of the microbial community with the toxic sulfide produced by Desulfobacterales. Collectively, these findings provided a theoretical basis for the mechanism of the sulfur cycle in subtropical mangrove ecosystems.
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Quynh Hoa, Kieu Thi, Phung Minh Hieu, Vy Tuan Anh, Do Chi Linh, Nguyen Thi Ngoc Quynh, Pham Thi Dau, Vuong Thi Nga, Nguyen Thi Yen, Nguyen Van Giang e Nguyen Xuan Canh. "Sulfate/sulfide removal from wastewater by lab-scale microbial fuel cell". Vietnam Journal of Biotechnology 19, n. 4 (3 maggio 2022): 779–84. http://dx.doi.org/10.15625/1811-4989/17110.
Testo completoAbstract (sommario):
Sulfate/sulfide-containing wastewater is a widespread environmental contaminant resulting from human activities. These pollutants have negative impact on natural ecosystems and human beings. Biological sulfate/sulfide removal can be achieved by reducing sulfate to sulfide with sulfate-reducing bacteria and then oxidizing sulfide to elemental sulfur (So) with sulfide oxidizing bacteria. In sulfate/sulfide contaminant wastewater lacking electron acceptor for sulfide oxidization, excess sulfide will be produced and accumulated in the treatment system. Therefore, microbial fuel cells (MFCs) have been shown to be a promising technique for the removal of sulfate/sulfide pollutants in wastewater. In this study, a lab-scale MFCs has been developed based on the activity of sulfate-reducing bacterium Desulfovibrio. sp. The results showed that sulfate and sulfide removal efficiencies of 74 - 82% (78 ± 2,5%) and 80.8 - 89.1% (~85,6 ± 3,1%) were achieved, respectively, from the 5th day to the 14th day of operation. The voltage of 0.02V and power density of 7.2 to 7.8 mW/m2 was obtained. In this study, sulfide oxidizing-based MFC integrated with sulfate-reducing bioreactor, representing the feasibility of simultaneous sulfate/sulfide pollutants removal and electricity generation in MFCs. This provides a promising treatment system to scale up for its actual applications in sulfate/sulfide removal.
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Andronikov, Alexandre V., Irina E. Andronikova e Tamara Sidorinova. "Trace-Element Geochemistry of Sulfides in Upper Mantle Lherzolite Xenoliths from East Antarctica". Minerals 11, n. 7 (16 luglio 2021): 773. http://dx.doi.org/10.3390/min11070773.
Testo completoAbstract (sommario):
Sulfides in upper mantle lherzolite xenoliths from Cretaceous alkaline-ultramafic rocks in the Jetty Peninsula (East Antarctica) were studied for their major and trace-element compositions using SEM and LA-ICP-MS applied in situ. Modal abundance of sulfides is the lowest in Cpx-poor lherzolites ≤ Spl-Grt lherzolites << Cpx-rich lherzolites. Most sulfides are either interstitial (i-type) or inclusions in rock-forming minerals (e-type) with minor sulfide phases mostly present in metasomatic veinlets and carbonate-silicate interstitial patches (m-type). The main sulfide assemblage is pentlandite + chalcopyrite ± pyrrhotite; minor sulfides are polydymite, millerite, violarite, siegenite, and monosulfide solution (mss). Sulfide assemblages in the xenolith matrix are a product of the subsolidus re-equilibration of primary mss at temperatures below ≤300 °C. Platinum group elements (PGE) abundances suggest that most e-type sulfides are the residues of melting processes and that the i-type sulfides are crystallization products of sulfide-bearing fluids/liquids. The m-type sulfides might have resulted from low-temperature metasomatism by percolating sulfide-carbonate-silicate fluids/melts. The PGE in sulfide record processes are related to partial melting in mantle and intramantle melt migration. Most other trace elements initially partitioned into interstitial sulfide liquid and later metasomatically re-enriched residual sulfides overprinting their primary signatures. The extent of element partitioning into sulfide liquids depends on P, T, fO2, and host peridotite composition.
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Gróf, Nikolas, Jana Barbušová, Kristína Hencelová e Miroslav Hutňan. "Absorption removal of hydrogen sulfide from recirculated biogas". Acta Chimica Slovaca 13, n. 1 (1 aprile 2020): 13–18. http://dx.doi.org/10.2478/acs-2020-0003.
Testo completoAbstract (sommario):
AbstractThis study is focused on the effect of biogas recirculation with hydrogen sulfide removal on anaerobic treatment of sulfur-enriched synthetic wastewater in a UASB reactor. The presence of hydrogen sulfide in biogas causes problems in its further energy recovery while sulfides inhibit the anaerobic process. The reactor was gradually loaded with sulfates and their effect on the reactor operation was monitored. At the same time, external absorption of hydrogen sulfide from biogas with absorbent regeneration was operated. The results show that low concentrations of added sulfates support biogas production. At the sulfate concentration of 125 mg l−1, biogas production increased by approximately 2 l d−1. However, further increasing of the amount of sulfates in the substrate led to the opposite effect. At twice the amount of sulfates, the biogas production decrease by 1 l d−1 and its adverse effects on the removal of N-NH4, NC and P-PO4 were observed. Biogas recirculation through the absorption column ensured a decrease in the hydrogen sulfide concentration from 19 960 ppm to 4 030 ppm and an increase in the methane content from 59.2 % to 83 % and also a decrease in the sulfides concentration in the reactor. From the measured data it can be concluded that this method reduces sulfides inhibition.
33
Demidenko, I. V., e V. M. Ishimov. "Electrochemical Deposition of ZnS Films from Electrolyte Based on Na2SO3". Elektronnaya Obrabotka Materialov 57, n. 5 (ottobre 2021): 20–26. http://dx.doi.org/10.52577/eom.2021.57.5.20.
Testo completoAbstract (sommario):
The paper considers the features of electrochemical growth of zinc sulfide from an aqueous electrolyte based on sodium sulfite and zinc sulfate. The conditions for the electrochemical production of ZnS films are determined. It is shown that the value of the potential at which a ZnS layer is formed is limited by the achievement of the critical current due to the diffusion limitations of the electrochemical process of reducing the sulfite ion. It is shown that the resulting films contain an excess of sulfur, which is removed, and the stoichiometric composition is obtained by heat treatment. Aed mechanism of reactions resulting in the formation of zinc sulfide is proposed.
34
Khanal, S. K., C. Shang e J. C. Huang. "Use of ORP (oxidation-reduction potential) to control oxygen dosing for online sulfide oxidation in anaerobic treatment of high sulfate wastewater". Water Science and Technology 47, n. 12 (1 giugno 2003): 183–89. http://dx.doi.org/10.2166/wst.2003.0645.
Testo completoAbstract (sommario):
In this study, oxidation-reduction potential (ORP) was used as a controlling parameter to regulate oxygen dosing to the recycled biogas for online sulfide oxidation in an upflow anaerobic filter (UAF) system. The UAF was operated with a constant influent COD of 18,000 mg/L, but with different influent sulfates of 1000, 3000 and 6000 mg/L. The reactor was initially operated under a natural ORP of -290 mV (without oxygen injection), and was then followed by oxygenation to raise its ORP by 25 mV above the natural level for each influent sulfate condition. At 6,000 mg/L sulfate without oxygen injection, the dissolved sulfide reached 733.8 mg S/L with a corresponding free sulfide of 250.3 mg S/L, thus showing a considerable inhibition to methanogens. Upon oxygenation to raise its ORP to -265 mV (i.e., a 25 mV increase), the dissolved sulfide was reduced by more than 98.5% with a concomitant 45.9% increase of the methane yield. Under lower influent sulfate levels of 1,000 and 3,000 mg/L, the levels of sulfides produced, even under the natural ORP, did not impose any noticeable toxicity to methanogens. Upon oxygenation to raise the ORP by +25 mV, the corresponding methane yields were actually reduced by 15.5% and 6.2%, respectively. However, such reductions were not due to the adverse impact of the elevated ORP; instead, they were due to a diversion of some organic carbon to support the facultative activities inside the reactor as a result of excessive oxygenation. In other words, to achieve satisfactory sulfide oxidation for the lower influent sulfate conditions, it was not necessary to raise the ORP by as much as +25 mV. The ORP increase actually needed depended on both the influent sulfate and also actual wastewater characteristics. This study had proved that the ORP controlled oxygenation was reliable for achieving consistent online sulfide control.
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Holmer, Marianne, William W. Bennett, Angus J. P. Ferguson, Jaimie Potts, Harald Hasler-Sheetal e David T. Welsh. "Drivers of sulfide intrusion in Zostera muelleri in a moderately affected estuary in south-eastern Australia". Marine and Freshwater Research 68, n. 11 (2017): 2134. http://dx.doi.org/10.1071/mf16402.
Testo completoAbstract (sommario):
The seagrass Zostera muelleri Irmisch ex Asch. is abundant in estuaries in Australia and is under pressure from coastal developments. We studied sulfide intrusion in Z. muelleri along a gradient of anthropogenic impact at five stations in the Wallis Lake estuary, Australia. Results showed differences in sediment biogeochemical conditions, seagrass metrics as well as nutrient content and sulfide intrusion along the gradient from the lower estuary (affected) to the lagoon (unaffected). Sulfide intrusion was driven by complex interactions and related to changes in seagrass morphology and sediment biogeochemistry and was modified by the exposure to wind and wave action. The sediments in the lower estuary had high contributions from phytoplanktonic detritus, whereas the organic pools in the lagoon were dominated by seagrass detritus. Despite high concentrations of organic matter, sulfide intrusion was lower at stations dominated by seagrass detritus, probably because of lower sulfide pressure from the less labile nature of organic matter. Porewater diffusive gradients in thin-film (DGT) sulfide samplers showed efficient sulfide reoxidation in the rhizosphere, with high sulfur incorporation in the plants from sedimentary sulfides being likely due to sulfate uptake from reoxidised sulfide. This is a unique adaptation of Z. muelleri, which allows high productivity in estuarine sediments.
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Anderson, Melissa O., Mark D. Hannington, Timothy F. McConachy, John W. Jamieson, Maria Anders, Henning Wienkenjohann, Harald Strauss, Thor Hansteen e Sven Petersen. "Mineralization and Alteration of a Modern Seafloor Massive Sulfide Deposit Hosted in Mafic Volcaniclastic Rocks". Economic Geology 114, n. 5 (1 agosto 2019): 857–96. http://dx.doi.org/10.5382/econgeo.4666.
Testo completoAbstract (sommario):
Abstract Tinakula is the first seafloor massive sulfide deposit described in the Jean Charcot troughs and is the first such deposit described in the Solomon Islands—on land or the seabed. The deposit is hosted by mafic (basaltic-andesitic) volcaniclastic rocks within a series of cinder cones along a single eruptive fissure. Extensive mapping and sampling by remotely operated vehicle, together with shallow drilling, provide insights into deposit geology and especially hydrothermal processes operating in the shallow subsurface. On the seafloor, mostly inactive chimneys and mounds cover an area of ~77,000 m2 and are partially buried by volcaniclastic sand. Mineralization is characterized by abundant barite- and sulfide-rich chimneys that formed by low-temperature (<250°C) venting over ~5,600 years. Barite-rich samples have high SiO2, Pb, and Hg contents; the sulfide chimneys are dominated by low-Fe sphalerite and are high in Cd, Ge, Sb, and Ag. Few high-temperature chimneys, including zoned chalcopyrite-sphalerite samples and rare massive chalcopyrite, are rich in As, Mo, In, and Au (up to 9.26 ppm), locally as visible gold. Below the seafloor, the mineralization includes buried intervals of sulfide-rich talus with disseminated sulfides in volcaniclastic rocks consisting mainly of lapillistone with minor tuffaceous beds and autobreccias. The volcaniclastic rocks are intensely altered and variably cemented by anhydrite with crosscutting sulfate (± minor sulfide) veins. Fluid inclusions in anhydrite and sphalerite from the footwall (to 19.3 m below seafloor; m b.s.f.) have trapping temperatures of up to 298°C with salinities close to, but slightly higher than, that of seawater (2.8–4.5 wt % NaCl equiv). These temperatures are 10° to 20°C lower than the minimum temperature of boiling at this depth (1,070–1,204 m below sea level; m b.s.l.), suggesting that the highest-temperature fluids boiled below the seafloor. The alteration is distributed in broadly conformable zones, expressed in order of increasing depth and temperature as (1) montmorillonite/nontronite, (2) nontronite + corrensite, (3) illite/smectite + pyrite, (4) illite/smectite + chamosite, and (5) chamosite + corrensite. Zones of argillic alteration are distinguished from chloritic alteration by large positive mass changes in K2O (enriched in illite/smectite), MgO (enriched in chamosite and corrensite), and Fe2O3 (enriched in pyrite associated with illite/smectite alteration). The δ18O and δD values of clay minerals confirm increasing temperature with depth, from 124° to 256°C, and interaction with seawater-dominated hydrothermal fluids at high water/rock ratios. Leaching of the volcanic host rocks and thermochemical reduction of seawater sulfate are the primary sources of sulfur, with δ34S values of sulfides, from –0.8 to 3.4‰, and those of sulfate minerals close to seawater sulfate, from 19.3 to 22.5‰. The mineralization and alteration at Tinakula are typical of a class of ancient massive sulfide deposits hosted mainly by permeable volcaniclastic rocks with broad, semiconformable alteration zones. Processes by which these deposits form have never been documented in modern seafloor massive sulfide systems, because they mostly develop below the seafloor. Our study shows how hydrothermal fluids can become focused within permeable rocks by progressive, low-temperature fluid circulation, leading to a large area (>150,000 m2) of alteration with reduced permeability close to the seafloor. In our model, overpressuring and fracturing of the sulfate- and clay-cemented volcaniclastic rocks produced the pathways for higher-temperature fluids to reach the seafloor, present now as sulfate-sulfide veins within the footwall. In the geologic record, the sulfate (anhydrite) is not preserved, leaving a broad zone of intense alteration with disseminated and stringer sulfides typical of this class of deposits.
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Holkenbrink, Carina, Santiago Ocón Barbas, Anders Mellerup, Hiroyo Otaki e Niels-Ulrik Frigaard. "Sulfur globule oxidation in green sulfur bacteria is dependent on the dissimilatory sulfite reductase system". Microbiology 157, n. 4 (1 aprile 2011): 1229–39. http://dx.doi.org/10.1099/mic.0.044669-0.
Testo completoAbstract (sommario):
Green sulfur bacteria (GSB) oxidize sulfide and thiosulfate to sulfate, with extracellular globules of elemental sulfur as an intermediate. Here we investigated which genes are involved in the formation and consumption of these sulfur globules in the green sulfur bacterium Chlorobaculum tepidum. We show that sulfur globule oxidation is strictly dependent on the dissimilatory sulfite reductase (DSR) system. Deletion of dsrM/CT2244 or dsrT/CT2245, or the two dsrCABL clusters (CT0851–CT0854, CT2247–2250), abolished sulfur globule oxidation and prevented formation of sulfate from sulfide, whereas deletion of dsrU/CT2246 had no effect. The DSR system also seems to be involved in the formation of thiosulfate, because thiosulfate was released from wild-type cells during sulfide oxidation, but not from the dsr mutants. The dsr mutants incapable of complete substrate oxidation oxidized sulfide and thiosulfate about twice as fast as the wild-type, while having only slightly lower growth rates (70–80 % of wild-type). The increased oxidation rates seem to compensate for the incomplete substrate oxidation to satisfy the requirement for reducing equivalents during growth. A mutant in which two sulfide : quinone oxidoreductases (sqrD/CT0117 and sqrF/CT1087) were deleted exhibited a decreased sulfide oxidation rate (∼50 % of wild-type), yet formation and consumption of sulfur globules were not affected. The observation that mutants lacking the DSR system maintain efficient growth suggests that the DSR system is dispensable in environments with sufficiently high sulfide concentrations. Thus, the DSR system in GSB may have been acquired by horizontal gene transfer as a response to a need for enhanced substrate utilization in sulfide-limiting habitats.
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Finster, Kai, Werner Liesack e Bo Thamdrup. "Elemental Sulfur and Thiosulfate Disproportionation by Desulfocapsa sulfoexigens sp. nov., a New Anaerobic Bacterium Isolated from Marine Surface Sediment". Applied and Environmental Microbiology 64, n. 1 (1 gennaio 1998): 119–25. http://dx.doi.org/10.1128/aem.64.1.119-125.1998.
Testo completoAbstract (sommario):
ABSTRACT A mesophilic, anaerobic, gram-negative bacterium, strain SB164P1, was enriched and isolated from oxidized marine surface sediment with elemental sulfur as the sole energy substrate in the presence of ferrihydrite. Elemental sulfur was disproportionated to hydrogen sulfide and sulfate. Growth was observed exclusively in the presence of a hydrogen sulfide scavenger, e.g., ferrihydrite. In the absence of a scavenger, sulfide and sulfate production were observed but no growth occurred. Strain SB164P1 grew also by disproportionation of thiosulfate and sulfite. With thiosulfate, the growth efficiency was higher in ferrihydrite-supplemented media than in media without ferrihydrite. Growth coupled to sulfate reduction was not observed. However, a slight sulfide production occurred in cultures incubated with formate and sulfate. Strain SB164P1 is the first bacterium described that grows chemolithoautotrophically exclusively by the disproportionation of inorganic sulfur compounds. Comparative 16S rDNA sequencing analysis placed strain SB164P1 into the delta subclass of the classProteobacteria. Its closest relative is Desulfocapsa thiozymogenes, and slightly more distantly related areDesulfofustis glycolicus and Desulforhopalus vacuolatus. This phylogenetic cluster of organisms, together with members of the genus Desulfobulbus, forms one of the main lines of descent within the delta subclass of theProteobacteria. Due to the common phenotypic characteristics and the phylogenetic relatedness to Desulfocapsa thiozymogenes, we propose that strain SB164P1 be designated the type strain of Desulfocapsa sulfoexigens sp. nov.
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MURUGANANTHAN, M. "Removal of sulfide, sulfate and sulfite ions by electro coagulation". Journal of Hazardous Materials 109, n. 1-3 (giugno 2004): 37–44. http://dx.doi.org/10.1016/j.jhazmat.2003.12.009.
Testo completo
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Findlay, Alyssa J., Valeria Boyko, André Pellerin, Khoren Avetisyan, Qingjun Guo, Xi Yang e Alexey Kamyshny. "Sulfide oxidation affects the preservation of sulfur isotope signals". Geology 47, n. 8 (6 giugno 2019): 739–43. http://dx.doi.org/10.1130/g46153.1.
Testo completoAbstract (sommario):
Abstract The accumulation of oxygen in Earth’s atmosphere and oceans in the late Archean had profound implications for the planet’s biogeochemical evolution. Oxygen impacts sulfur cycling through the oxidation of sulfide minerals and the production of sulfate for microbial sulfate reduction (MSR). The isotopic signature of sulfur species preserved in the geologic record is affected by the prevailing biological and chemical processes and can therefore be used to constrain past oxygen and sulfate concentrations. Here, in a study of a late Archean analogue, we find that the sulfur isotopic signature in the water column of a seasonally stratified lake in southern China is influenced by MSR, whereas model results indicate that the isotopic signature of the underlying sediments can be best explained by concurrent sulfate reduction and sulfide oxidation. These data demonstrate that small apparent sulfur isotope fractionations (δ34Ssulfate-AVS = 4.2‰–1.5‰; AVS—acid volatile sulfides) can be caused by dynamic sulfur cycling at millimolar sulfate concentrations. This is in contrast to current interpretations of the isotopic record and indicates that small fractionations do not necessarily indicate very low sulfate or oxygen.
41
Agarbati, Alice, Laura Canonico, Francesca Comitini e Maurizio Ciani. "Reduction of Sulfur Compounds through Genetic Improvement of Native Saccharomyces cerevisiae Useful for Organic and Sulfite-Free Wine". Foods 9, n. 5 (20 maggio 2020): 658. http://dx.doi.org/10.3390/foods9050658.
Testo completoAbstract (sommario):
Sulfites and sulfides are produced by yeasts in different amounts depending on different factors, including growth medium and specific strain variability. In natural must, some strains can produce an excess of sulfur compounds that confer unpleasant smells, inhibit malolactic fermentation and lead to health concerns for consumers. In organic wines and in sulfite-free wines the necessity to limit or avoid the presence of sulfide and sulfite requires the use of selected yeast strains that are low producers of sulfur compounds, with good fermentative and aromatic aptitudes. In the present study, exploiting the sexual mass-mating spores’ recombination of a native Saccharomyces cerevisiae strain previously isolated from grape, three new S. cerevisiae strains were selected. They were characterized by low sulfide and sulfite production and favorable aromatic imprinting. This approach, that occurs spontaneously also in nature, allowed us to obtain new native S. cerevisiae strains with desired characteristics that could be proposed as new starters for organic and sulfite-free wine production, able to control sulfur compound production and to valorize specific wine types.
42
Wulansari, Isma. "Sulfiden Removal by Catalitic Oxidation From Rayon Waste". Devotion Journal of Community Service 4, n. 2 (23 febbraio 2023): 615–23. http://dx.doi.org/10.36418/devotion.v4i2.414.
Testo completoAbstract (sommario):
Catalytic oxidation of spent sulfidic caustic consist of SH- ion or NaHS compound by H 2 O2 in neutral or acidic solution to elemental sulphur may provide a convenient and economical method for the control of sulphide wastes and their associated odors at pulp, paper and textile industry. Oxidation of sulfide in rayon waste by hydrogen peroxide was investigated in the presence of ferric sulfate catalyst. Kinetic equations and activation energies of H 2 O2 and SH- ion to total sulphur and sulphate in rayon waste for catalytic oxidation reaction were calculated based on the experimental results. For the removal of sulfide from sulfide solution the most common process involves its catalytic oxidation to a more benign form sulfate. The rate of sulfidic catalytic oxidation was found higher at lower initial sulphide concentration and the rate of sulphide catalytic oxidation was found directly proportional to loading and hydrogen peroxide addition. Optimum total sulphide concentration was achieved when sulphide solutions in the presence of H 2 O 2 in the ratios SH-/H 2 O 2 1:4.2. The potential user of H 2 O 2 determine the optimal conditions for control of odor, corrosion and waste treatment cost due to sulfide consisting of sulphur ion, sulphate ion, etc. The catalytic oxidation of sulphides into sulphates by H 2 O 2 may be applied directly to aqueous wastes containing these odorants
43
Jeans, Christopher V., Alexandra V. Turchyn e Xu-Fang Hu. "Sulfur isotope patterns of iron sulfide and barite nodules in the Upper Cretaceous Chalk of England and their regional significance in the origin of coloured chalks". Acta Geologica Polonica 66, n. 2 (1 giugno 2016): 227–56. http://dx.doi.org/10.1515/agp-2016-0010.
Testo completoAbstract (sommario):
AbstractThe relationship between the development of iron sulfide and barite nodules in the Cenomanian Chalk of England and the presence of a red hematitic pigment has been investigated using sulfur isotopes. In southern England where red and pink chalks are absent, iron sulfide nodules are widespread. Two typical large iron sulfide nodules exhibit δ34S ranging from −48.6‰ at their core to −32.6‰ at their outer margins. In eastern England, where red and pink chalks occur in three main bands, there is an antipathetic relationship between the coloured chalks and the occurrence of iron sulfide or barite nodules. Here iron sulfide, or its oxidised remnants, are restricted to two situations: (1) in association with hard grounds that developed originally in chalks that contained the hematite pigment or its postulated precursor FeOH3, or (2) in regional sulfidization zones that cut across the stratigraphy. In the Cenomanian Chalk exposed in the cliffs at Speeton, Yorkshire, pyrite and marcasite (both iron sulfide) nodules range in δ34S from −34.7‰ to +40.0‰. In the lower part of the section δ34S vary from −34.8‰ to +7.8‰, a single barite nodule has δ34S between +26.9‰ and +29.9‰. In the middle part of the section δ34S ranges from +23.8‰ to +40.0‰. In the sulfidization zones that cut across the Cenomanian Chalk of Lincolnshire the iron sulfide nodules are typically heavily weathered but these may contain patches of unoxidised pyrite. In these zones, δ34S ranges from −32.9‰ to +7.9‰. The cross-cutting zones of sulfidization in eastern England are linked to three basement faults – the Flamborough Head Fault Zone, the Caistor Fault and the postulated Wash Line of Jeans (1980) – that have affected the deposition of the Chalk. It is argued that these faults have been both the conduits by which allochthonous fluids – rich in hydrogen sulfide/sulfate, hydrocarbons and possibly charged with sulfate-reducing bacteria – have penetrated the Cenomanian Chalk as the result of movement during the Late Cretaceous or Cenozoic. These invasive fluids are associated with (1) the reduction of the red hematite pigment or its praecursor, (2) the subsequent development of both iron sulfides and barite, and (3) the loss of overpressure in the Cenomanian Chalk and its late diagenetic hardening by anoxic cementation. Evidence is reviewed for the origin of the red hematite pigment of the coloured chalks and for the iron involved in the development of iron sulfides, a hydrothermal or volcanogenic origin is favoured.
44
Jackson, Bradley E., e Michael J. McInerney. "Thiosulfate Disproportionation byDesulfotomaculum thermobenzoicum". Applied and Environmental Microbiology 66, n. 8 (1 agosto 2000): 3650–53. http://dx.doi.org/10.1128/aem.66.8.3650-3653.2000.
Testo completoAbstract (sommario):
ABSTRACT Desulfotomaculum thermobenzoicum, but notDesulfotomaculum nigrificans, Desulfotomaculum ruminis, or Desulfosporosinus orientis, grew by disproportionation of thiosulfate, forming stoichiometric amounts of sulfate and sulfide; sulfite was not disproportionated. The addition of acetate enhanced growth and thiosulfate disproportionation by D. thermobenzoicum compared to those observed with thiosulfate alone.
45
Kertesz, Michael A., Karen Schmidt-Larbig e Thomas Wüest. "A Novel Reduced Flavin Mononucleotide-Dependent Methanesulfonate Sulfonatase Encoded by the Sulfur-Regulatedmsu Operon of Pseudomonas aeruginosa". Journal of Bacteriology 181, n. 5 (1 marzo 1999): 1464–73. http://dx.doi.org/10.1128/jb.181.5.1464-1473.1999.
Testo completoAbstract (sommario):
ABSTRACT When Pseudomonas aeruginosa is grown with organosulfur compounds as sulfur sources, it synthesizes a set of proteins whose synthesis is repressed in the presence of sulfate, cysteine, or thiocyanate (so-called sulfate starvation-induced proteins). The gene encoding one of these proteins, PA13, was isolated from a cosmid library of P. aeruginosa PAO1 and sequenced. It encoded a 381-amino-acid protein that was related to several reduced flavin mononucleotide (FMNH2)-dependent monooxygenases, and it was the second in an operon of three genes, which we have namedmsuEDC. The MsuD protein catalyzed the desulfonation of alkanesulfonates, requiring oxygen and FMNH2 for the reaction, and showed highest activity with methanesulfonate. MsuE was an NADH-dependent flavin mononucleotide (FMN) reductase, which provided reduced FMN for the MsuD enzyme. Expression of the msuoperon was analyzed with a transcriptionalmsuD::xylE fusion and was found to be repressed in the presence of sulfate, sulfite, sulfide, or cysteine and derepressed during growth with methionine or alkanesulfonates. Growth with methanesulfonate required an intact cysB gene, and themsu operon is therefore part of the cysregulon, since sulfite utilization was found to be CysB independent in this species. Measurements ofmsuD::xylE expression incysN and cysI genetic backgrounds showed that sulfate, sulfite, and sulfide or cysteine play independent roles in negatively regulating msu expression, and sulfonate utilization therefore appears to be tightly regulated.
46
Vysotskiy, Sergey V., Tatyana A. Velivetskaya, Aleksandr V. Ignatiev, Aleksandr I. Slabunov e Anna V. Aseeva. "Multiple Sulfur Isotope Evidence for Bacterial Sulfate Reduction and Sulfate Disproportionation Operated in Mesoarchaean Rocks of the Karelian Craton". Minerals 12, n. 9 (9 settembre 2022): 1143. http://dx.doi.org/10.3390/min12091143.
Testo completoAbstract (sommario):
Sulfur isotope in sulfides from the Paleoarchean and the Neoarchean sedimentary rocks evidence microbial sulfur metabolism in Archean sulfur cycle. However, sulfur metabolism for the Mesoarchean interval is less obvious since evidence for a large range in sulfur isotope values has not yet been observed in Mesoarchean samples. We report the results of multiple sulfur isotope measurements for sulfide minerals from ~2.8 Ga sedimentary rocks in the southeastern part of the Karelian Craton. In situ isotope analysis of sulfide grains have been performed using a femtosecond laser-ablation fluorination method. Sulfide samples studied here yielded Δ33S values between −0.3 and +2.7‰ and δ34S values between −10 and +33‰. The Δ33S dataset was interpreted to indicate the incorporation of sulfur from two coexisting sulfur pools, photolytic sulfate and photolytically derived elemental sulfur. We suggest that the relative contributions of these Δ33S different pools to the pyritic sulfur could be controlled by the metabolic activity of coexisting sulfate-reducing and sulfur-disproportionating bacteria during pyrite formation. We therefore suggest the operation of different metabolic pathways of sulfur in Mesoarchean sedimentary environments.
47
Yap, Pei Lay, Yow Loo Au Yoong, Muralithran G. Kutty, Olaf Timpe, Malte Behrens e Sharifah Bee Abdul Hamid. "Facile Remediation Method of Copper Sulfide by Nitrogen Pre-Treatment". Advanced Materials Research 361-363 (ottobre 2011): 1445–50. http://dx.doi.org/10.4028/www.scientific.net/amr.361-363.1445.
Testo completoAbstract (sommario):
The deactivation and destabilization of copper sulfide when exposed to an oxidizing environment has led to the economical concerns as this sulfidic material can be easily destroyed by a series of oxidation processes. A promising and effective remediation technique in limiting the contact between covellite (CuS) and oxygen has been developed using a simple, hassle-free, non-corrosive, and eco-friendly pre-treatment of nitrogen approach. This remediation technique is remarkably effective as various techniques such as powder XRD, EDX, elemental mapping, and TGA-MS analyses have confirmed that covellite prepared with the pre-treatment of nitrogen does not oxidize to any mixed phase compound. Meanwhile, the study also shows that covellite stored without the pre-treatment of nitrogen has transformed to a mixed phase of pentahydrate copper sulfate and covellite. Hence, this method can be practically exercised not only on covellite, but possibly on other metal sulfides which are prone to be attacked by oxygen and water molecules in oxidizing environment.
48
Bataleva, Yuliya, Yuri Palyanov e Yuri Borzdov. "Sulfide Formation as a Result of Sulfate Subduction into Silicate Mantle (Experimental Modeling under High P,T-Parameters)". Minerals 8, n. 9 (29 agosto 2018): 373. http://dx.doi.org/10.3390/min8090373.
Testo completoAbstract (sommario):
Ca,Mg-sulfates are subduction-related sources of oxidized S-rich fluid under lithospheric mantle P,T-parameters. Experimental study, aimed at the modeling of scenarios of S-rich fluid generation as a result of desulfation and subsequent sulfide formation, was performed using a multi-anvil high-pressure apparatus. Experiments were carried out in the Fe,Ni-olivine–anhydrite–C and Fe,Ni-olivine–Mg-sulfate–C systems (P = 6.3 GPa, T of 1050 and 1450 °C, t = 23–60 h). At 1050 °C, the interaction in the olivine–anhydrite–C system leads to the formation of olivine + diopside + pyrrhotite assemblage and at 1450 °C leads to the generation of immiscible silicate-oxide and sulfide melts. Desulfation of this system results in the formation of S-rich reduced fluid via the reaction olivine + anhydrite + C → diopside + S0 + CO2. This fluid is found to be a medium for the recrystallization of olivine, extraction of Fe and Ni, and subsequent crystallization of Fe,Ni-sulfides (i.e., olivine sulfidation). At 1450 °C in the Ca-free system, the generation of carbonate-silicate and Fe,Ni-sulfide melts occurs. Formation of the carbonate component of the melt occurs via the reaction Mg-sulfate + C → magnesite + S0. It is experimentally shown that the olivine-sulfate interaction can result in mantle sulfide formation and generation of potential mantle metasomatic agents—S- and CO2-dominated fluids, silicate-oxide melt, or carbonate-silicate melt.
49
Puhakka, J. A., J. A. Rintala e P. Vuoriranta. "Influence of Sulfur Compounds on Biogas Production from Forest Industry Wastewater". Water Science and Technology 17, n. 1 (1 gennaio 1985): 281–88. http://dx.doi.org/10.2166/wst.1985.0023.
Testo completoAbstract (sommario):
Various inorganic sulfur compounds and lignosulfonate were studied with respect to their effect on biogas production from synthetic wastewater simulating sulfite evaporator condensate. The sulfur balance during the anaerobic degradation was also investigated. In biogas production assay tests municipal digester sludge was used as seed material. Differences in sulfur inhibition of methanogenesis between various oxidation states of inorganic sulfur were detected. Sulfate and sulfide in concentrations 100 mg S/l had no effect whereas sulfite, thiosulfate and dithionite caused a lag-period in biogas production. Reduced biogas production was observed even with the addition of 1000 mg S/l as SO=4, SO=3 and S2O=3. Dithionite was the most toxic compound investigated. Sodiumlignosulfonate in concentrations 5-15 g/l has a supplementary increase in biogas production. Inorganic sulfur compounds were partially reduced to sulfide in anaerobic conditions.
50
Kieu, Thi Quynh Hoa, Thi Yen Nguyen e Chi Linh Do. "Effect of Different Catholytes on the Removal of Sulfate/Sulfide and Electricity Generation in Sulfide-Oxidizing Fuel Cell". Molecules 28, n. 17 (29 agosto 2023): 6309. http://dx.doi.org/10.3390/molecules28176309.
Testo completoAbstract (sommario):
Microbial fuel cells are one of the alternative methods that generate green, renewable sources of energy from wastewater. In this study, a new bio-electrochemical system called the sulfide-oxidizing fuel cell (SOFC) is developed for the simultaneous removal of sulfide/sulfide and electricity generation. To improve the application capacity of the SOFC, a system combining sulfate-reducing and sulfide-oxidizing processes for sulfate/sulfide removal and electricity generation was designed. Key factors influencing the sulfide-removal efficiency and electricity-generation capacity of the SOFC are the anolytes and catholytes. The sulfide produced from the sulfate-reducing process is thought to play the key role of an electron mediator (anolyte), which transfers electrons to the electrode to produce electricity. Sulfide can be removed in the anodic chamber of the SOFC when it is oxidized to the element sulfur (S°) through the biochemical reaction at the anode. The performance of wastewater treatment for sulfate/sulfide removal and electricity generation was evaluated by using different catholytes (dissolved oxygen in deionized water, a phosphate buffer, and ferricyanide). The results showed that the sulfate-removal efficiency is 92 ± 1.2% during a 95-day operation. A high sulfide-removal efficiency of 93.5 ± 1.2 and 83.7 ± 2% and power density of 18.5 ± 1.1 and 15.2 ± 1.2 mW/m2 were obtained with ferricyanide and phosphate buffers as the catholyte, respectively, which is about 2.6 and 2.1 times higher than dissolved oxygen being used as a catholyte, respectively. These results indicated that cathode electron acceptors have a direct effect on the performance of the treatment system. The sulfide-removal efficiency and power density of the phosphate buffer SOFC were only slightly less than the ferricyanide SOFC. Therefore, a phosphate buffer could serve as a low-cost and effective pH buffer for practical applications, especially for wastewater treatment. The results presented in this study clearly revealed that the integrated treatment system can be effectively applied for sulfate/sulfide removal and electricity generation simultaneously.