Sulfur Abundance Research Articles

Absorption of Sulphur Onto Organoclay

Due to the abundance of sulphur found in soil under Aerobic condition the main element is being absorbed by the plant and it is brought from three major sources weathered they compose organic matter and atmospheric precipitation. Modified clay is suitable absorbent for the removal of sulphate from contaminated water in terms of natural and commercial absorbent. The maximum sulphate was found to be 119mg/L and 13mg/L for modified and unmodified clay at pH of 7.5 in three hours with 580mg/L of initial concentration.

Titanium silicalite as a radical-redox mediator for high-energy-density lithium-sulfur batteries.

Lithium-sulfur (Li-S) batteries are receiving intense interest owing to their high energy densities, cost effectiveness, and the natural abundance of sulfur. However, practical applications are still limited by rapid capacity decay caused by multielectron redox reactions and complex phase transformations. Here, we include commercially available titanium silicalite-1 (TS-1) in carbon/sulfur cathodes, to introduce strong chemical interactions between the lithium polysulfides (LiPS) and TS-1 in a working Li-S battery. In situ UV-visible spectroscopy together with other experimental results confirm that incorporation of TS-1 mediators enables direct conversion between S82- and S3*- radicals during the discharge process, which effectively promotes the kinetic behaviors of soluble LiPS and regulates uniform nucleation and growth of solid sulfide precipitates. These features give our TS-1 engineered sulfur cathode an ultrahigh initial capacity of 1459 mA h g-1 at 0.1C. Moreover, the system has an impressively high areal capacity (3.84 mA h cm-2) and long cycling stability with a high sulfur loading of 4.9 mg cm-2. This novel and low-cost fabrication procedure is readily scalable and provides a promising avenue for potential industrial applications.

Freestanding oxidized poly(acrylonitrile-co-vinylpyrrolidone)/SnCl2 nanofibers as interlayer for Lithium[sbnd]Sulfur batteries

LithiumSulfur batteries are one of the most promising energy storage systems among the next generation batteries due to their high energy density and the natural abundance of sulfur. Nevertheless, some limitations hinder their implementation to the marketplace which are mostly linked to the shuttle effect resulting fast capacity lost and lithium poisoning by dissolved polysulfides. One of the possible solutions is the use of polysulfide adsorptive interlayers between anode and cathode to inhibit the shuttle effect protecting lithium anode. In this work, oxidized poly(acrylonitrile-co-vinylpyrrolidone) nanofibers containing SnCl2 (oPANVP/SnCl2) are used as an interlayer to enhance the performance of LiS cells. Unlike most of the current literature, the electrospun nanofiber mats are oxidized at 200 °C under air, but not further pyrolyzed to benefit from the functional groups and the partial formation of SnOx. 700 mAh g−1 discharge capacity is obtained at C/5 after 100 cycles by using oPANVP/SnCl2, which is higher than the cells with oPANVP and without interlayer. The improved capacity is mostly associated with the complementary adsorption effect of SnCl2 particles, partially formed SnOx and functional groups of oPANVP. Polysulfide adsorption effect of SnCl2, SnOx, and nitrogen- and oxygen-rich functional groups of oPANVP is proven by X-Ray Photoelectron Spectroscopy.

Smart Merit Combination of Sulfur, Selenium and Electrode Engineering To Build Better Sustainable Li-Storage Batteries

Given the giant theoretical capacity and great natural abundance of sulfur (S), Li-S batteries have been regarded as one of the most promising sustainable power sources in the future. However, they have to suffer from issues of short cyclic lifespan, low Coulombic efficiency, and poor rate behaviors unfortunately due to the insulating nature for S actives and negative polysulfide intermediates dissolution. As a congener, the conducting selenium (Se) shows the similar Li-storage chemistry to S, with comparable volumetric capacity, superb rate capability, but unluckily low gravimetric capacity and limited cyclic life. To build sustained power systems with preferable behaviors, we put forward an efficient battery promotion strategy by combining merits of S, Se and smart electrode engineering. Herein, Se and S are successively infused into a carbon black (CB) matrix and further packaged by thin nickel nitrate hydroxide layers (S/Se@CB⊂NNH) so as to suppress the actives diffusion losses. Such integrated S/Se@C...

Records of carbon and sulfur cycling during the Silurian Ireviken Event in Gotland, Sweden

Abstract Early Silurian (∼431 Ma) carbonate rocks record a ca. 4.5‰ positive excursion in the stable isotopic composition of carbonate carbon (δ13Ccarb). Associated with this isotopic shift is a macroevolutionary turnover pulse known as the ‘Ireviken Event’. The onset of this carbon isotope excursion is commonly associated with a shallowing-upward facies transition that may have been accompanied by climatic change, as indicated by a parallel positive shift (∼0.6‰) in the stable isotopic composition of carbonate oxygen (δ18Ocarb). However, the relationships among carbon cycle perturbations, faunal turnover, and environmental changes remain enigmatic. Here we present a suite of new isotopic data across the Ireviken Event from multiple sections in Gotland, Sweden. These samples preserve no systematic change in δ18Ocarb but show positive excursions of equal magnitude in both carbonate (δ13Ccarb) and organic (δ13Corg) carbon. In addition, the data reveal a synchronous perturbation in sulfur isotope ratios, manifest as a ca. 7‰ positive excursion in carbonate-associated sulfate (δ34SCAS) and a ca. 30‰ positive excursion in pyrite (δ34Spyr). The increase in δ34Spyr values is accompanied by a substantial, concomitant increase in stratigraphic variability of δ34Spyr. The relatively constant offset between the δ13Ccarb and δ13Corg excursions throughout the Ireviken Event could be attributed to increased organic carbon burial, or possibly a change in the isotopic composition of CO2 sources from weathering. However, a positive correlation between carbonate abundance and δ13Ccarb suggests that local to regional changes in dissolved inorganic carbon (DIC) during the shallowing-upward sequence may have been at least partly responsible for the observed excursion. The positive excursion recorded in δ34SCAS suggests a perturbation of sufficient magnitude and duration to have impacted the marine sulfate reservoir. An inverse correlation between CAS abundance and δ34SCAS supports the notion of decreased sulfate concentrations, at least locally, consistent with a concomitant increase in pyrite burial. A decrease in the offset between δ34SCAS and δ34Spyr values during the Ireviken Event suggests a substantial reduction in the isotopic fractionations (epyr) expressed during microbial sulfur cycling and pyrite precipitation through this interval. Decreased epyr and the concomitant increase in stratigraphic variation in δ34Spyr are typical of isotope systematics observed in modern shallow-water environments, associated with increased closed-system behavior and/or oxidative sedimentary reworking during early sediment diagenesis. While the isotopic trends associated with the Ireviken Event have been observed in multiple locations around the globe, many sections display different magnitudes of isotopic change, and moreover, are typically associated with local facies changes. Due to the stratigraphic coherence of the carbon and sulfur isotopic and abundance records across the Ireviken Event, and their relationship to changes in local depositional environment, we surmise that these patterns more closely reflect biogeochemical processes related to deposition and lithification of sediment than global changes in carbon and sulfur burial fluxes.

Applications of thermal desorption coupled to comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry for hydrocarbon fingerprinting of hydraulically fractured shale rocks

Development of shale gas resources through the use of hydraulic fracturing has raised a multitude of environmental concerns and motivated research towards the understanding of shale gas systems. Previous research has demonstrated the potential of utilizing hydrocarbon distributions towards the fingerprinting of a potential environmental contamination event arising from shale gas operations. However, to apply hydrocarbon distributions from shale gas wells towards point-source identification and apportionment, a better understanding of hydrocarbon origins must be achieved. Here we present an efficient and repeatable thermal desorption method, as a sample introduction methodology for GC × GC analysis of shale rock samples that results in comparable chromatograms to those produced by solvent extraction. This novel and robust characterization technique of shale cores from Marcellus and Utica formations by thermal desorption followed by GC × GC enables the understanding of hydrocarbon speciation within the native rock with minimal sample preparation time and solvent use. The detailed shale chemistry gives insight into utilizing hydrocarbon differences towards point-source identification methodologies of environmental contamination events associated with unconventional gas development. Additionally, this analytical technique may provide a more detailed analysis of hydrocarbons than what is currently implemented in the industry to pinpoint the most advantageous areas to exploit by hydraulic fracturing, yet avoiding undesirable areas such as those with a high abundance of sulfur containing compounds.

Quantitative Raman calibration of sulfate-bearing polymineralic mixtures: a S quantification in sedimentary rocks on Mars

AbstractThe NASA 2020 Mars mission is a Curiosity-type rover whose objective is to improve the knowledge of the geological and climatic evolution of Mars and to collect rock samples for return to Earth. The new rover has a payload of seven instruments including the SuperCam instrument which consists of four tools including a Raman spectrometer. This Raman device will be non-destructive and will analyse the surface remotely in order to determine the mineralogy of rocks and, by extent, to detect and quantify major elements such as sulfur. Sulfur has been detected as sulfate (Ca,Mg,Fe-sulfates) in sedimentary rocks. This element is difficult to quantify using the laser ablation tool of the ChemCam instrument on-board the Curiosity rover.We propose a Raman calibration to constrain the sulfur abundance in polymineralic mixtures. We acquired Raman signatures on binary and ternary mechanical mixtures containing Ca and Mg sulfates, mixed with natural silicate minerals supposed to be relevant to basaltic-sedimentary rocks at the surface of Mars: olivine, clinopyroxene, orthopyroxene and plagioclase. Using the Voigt function to process the Raman spectra from samples extracted from our mixtures allows us to calculate the initial proportions of our preparations of Ca and Mg sulfates. From these simulations, calibration equations have been provided allowing us to determine sulfate proportions (CaSO4and MgSO4) in a mixture with basaltic minerals. With the presented calibration, S can be quantified at a lower limit of 0.7 wt.% in Martian soil.

Chemistry in disks

Context. Several sulfur-bearing molecules are observed in the interstellar medium and in comets, in strong contrast to protoplanetary disks where only CS, H2CS, and SO have been detected so far. Aims. We combine observations and chemical models to constrain the sulfur abundances and their sensitivity to physical and chemical conditions in the DM Tau protoplanetary disk. Methods. We obtained 0.5′′ Atacama Large Millimeter Array observations of DM Tau in Bands 4 and 6 in lines of CS, SO, SO2, OCS, CCS, H2CS, and H2S, achieving a ~5 mJy sensitivity. Using the non-Local Thermodynamical Equilibrium radiative transfer code RADEX and the forward-modeling tool DiskFit, disk-averaged CS column densities and upper limits for the other species were derived. Results. Only CS was detected with a derived column density of ~2−6 × 1012 cm−2. We report a first tentative detection of SO2 in DM Tau. The upper limits range between ~1011 and 1014 cm−2 for the other S-bearing species. The best-fit chemical model matching these values requires a gas-phase C/O ratio of ≳1 at r ≳ 50−100 au. With chemical modeling we demonstrate that sulfur-bearing species could be robust tracers of the gas-phase C/O ratio, surface reaction rates, grain size and UV intensities. Conclusions. The lack of detections of a variety of sulfur-bearing molecules in DM Tau other than CS implies a dearth of reactive sulfur in the gas phase, either through efficient freeze-out or because most of the elemental sulfur is in other large species, as found in comets. The inferred high CS/SO and CS/SO2 ratios require a non-solar C/O gas-phase ratio of ≳1, consistent with the recent observations of hydrocarbon rings in DM Tau. The stronger depletion of oxygen-bearing S-species compared to CS is likely linked to the low observed abundances of gaseous water in DM Tau and points to a removal mechanism of oxygen from the gas.

Enhancing the Performance and Life Cycle of Lithium –Sulfur Batteries by Nanostructured Carbon and Different Additives

Lithium sulfur (Li – S) battery has been considered as one of the most promising rechargeable batteries among various energy storage devices owing to their low cost, high specific capacity and energy density. Over the last decade, lithium sulfur (Li – S) batteries have been extensively studied because of the abundance of sulfur, their environmental benignity, and high gravimetric (2600 W h Kg-1) and (2800 W h L-1) energy densities and are promising candidates for meeting future-energy storage demands. However, the insulation of sulfur and high solubility of lithium poly sulfides, swelling of cathode value and formation of lithium dendrites results in the low utilization and poor cycling performance. Significant efforts have been made to trap poly sulfides via physical strategies using carbon based materials, but interactions between poly sulfides and carbon are so weak that the device performance is limited. Chemical strategies provide the relatively complemented routes for improving the batteries' electrochemical properties by introducing strong interactions between functional groups and (oxygen, nitrogen and boron, etc.) and chemical additives (metal, polymers, etc.) to the carbon structure and how these foreign guests immobilize the dissolved polysulfide. This review focused on recent studies have reported various material such as metal oxides and sulfides that interact strongly with poly sulfides species and can alleviate the dissolution problem by comparing the poly sulfides adsorption capability candidate materials to provide the useful strategy to screen for suitable candidate materials and valuable information for rational design. Overcoming the loss of active mass and stabilizing cell capacity at high rates is pivotal to the realization of practical Li-S cells. In this review, different separate concepts and materials were studied with the aim to improve the Li-S batteries capacity, cycle life and capacity retention.

Multicomponent H2 in DLA at zabs = 2.05: physical conditions through observations and numerical models★

We perform detailed spectroscopic analysis and numerical modelling of an H2-bearing damped Lyman-alpha absorber (DLA) at zabs = 2.05 towards the quasar FBQS J2340-0053. Metal absorption features arise from fourteen components spread over $\Delta v_{90}$ = 114 km s$^{-1}$, seven of which harbour H2. Column densities of atomic and molecular species are derived through Voigt profile analysis of their absorption lines. We measure total N(H I), N(H2) and N(HD) to be 20.35+/-0.05, 17.99+/-0.05 and 14.28+/-0.08 (log cm$^{-2}$) respectively. H2 is detected in the lowest six rotational levels of the ground vibrational state. The DLA has metallicity, Z = 0.3 Z$_\sun$ ([S/H] = -0.52+/-0.06) and dust-to-gas ratio, $\kappa$ = 0.34+/-0.07. Numerical models of the H2 components are constrained individually to understand the physical structure of the DLA. We conclude that the DLA is subjected to the metagalactic background radiation and cosmic ray ionization rate of $\sim$ 10$^{-15.37}$ s$^{-1}$. Dust grains in this DLA are smaller than grains in the Galactic interstellar medium. The inner molecular regions of the H2 components have density, temperature and gas pressure in the range 30-120 cm$^{-3}$, 140-360 K and 7,000-23,000 cm$^{-3}$ K respectively. Micro-turbulent pressure is a significant constituent of the total pressure, and can play an important role in these innermost regions. Our H2 component models enable us to constrain component-wise N(H I), and elemental abundances of sulphur, silicon, iron and carbon. We deduce the line-of-sight thickness of the H2-bearing parts of the DLA to be 7.2 pc.

Signatures of the Martian regolith components entrained in some impact‐melt glasses in shergottites

AbstractMartian regolith components are found in some impact melts (IM) containing Martian atmospheric gases in the shergottites Elephant Moraine (EET) 79001, Tissint, Zagami, and Shergotty. Excess sulfur abundances provide strong indicators for the presence of an exogenous component. High sulfur abundances and the SO3‐SiO2 correlation in polished thin section (PTS) EET 79001,507 (here #507) are comparable to those in Martian soils. Correlations of SO3 with FeO in #507 from Lithology B and of CaO and Al2O3 in EET 79001,506 (here #506) from Lithology A suggest the possible occurrence of two varieties of sulfate‐bearing phases in impact‐melt precursors. Fe/S (atomic) ratios of 1.02–1.34 determined in several sulfide blebs in #507 differ from those determined in igneous sulfides (Fe/S = 0.92), and suggest that most sulfide blebs in #507 are not related to igneous sulfides. Fe/S (atomic) ratios in a Tissint glass range from ~0.5 (pyrite) to >1.1 suggesting a mixture of sulfur‐bearing phases. S K‐XANES spectra of the blebs in EET 79001 and Tissint glasses show that sulfur occurs as mixed amorphous sulfide and sulfite. The δ34S values and the 87Sr/86Sr (I) ratios determined in EET 79001 impact melts are consistent with the proposition that the sulfide blebs result from decomposition of secondary sulfates into sulfites during shock heating followed by reduction to sulfides by isentropic cooling. These results suggest the presence in some shergottites of extraneous regolith components containing oxidized S‐bearing species resembling sulfur species present in Martian soils.

Improving the Stability of an RT‐NaS Battery via In Situ Electrochemical Formation of Protective SEI on a Sulfur–Carbon Composite Cathode

AbstractThe room temperature sodium sulfur battery (RT‐NaS) has attracted considerable attention as a next‐generation energy storage system due to its low cost and high specific energy and the abundance of sodium and sulfur. However, the sulfur‐based cathode in RT‐NaS always undergoes dissolution of polysulfides during the cycle, which limits the utilization of active material and the stability of the RT‐NaS. In this study, the authors report an economical and simple method to suppress the dissolution of polysulfides by forming an artificial protective solid electrolyte interphase (SEI) on the cathode surface using an in situ electrochemical treatment with a fluoroethylene carbonate (FEC) electrolyte additive. The artificially formed SEI has a thickness of ≈20 nm and contains fluoride anions that improve electrical conductivity and mechanical stability. The RT‐NaS full cell with the sulfur–carbon cathode and protective SEI exhibits a 0.1 VNa+/Na lower electrochemical polarization for desodiation, and SEI and electrical resistances that are 23% and 45% lower, respectively, than those of untreated NaS. These improvements lead to a capacity increase of ≈120% (270 to 590 mAh g−1 at the 50th cycle) and a high Coloumbic efficiency of 99.5% in the high‐rate cyclability test of the 2 C rate over 200 cycles.

Evidence for oxidation at the base of the nakhlite pile by reduction of sulfate salts at the time of lava emplacement

The assimilation of sulfate by Martian melts could explain the highly oxidized state of some Martian nakhlite meteorites, such as those paired with MIL 03346 (MIL 090030, MIL 090032, and MIL 090136). Here, a combination of new sulfur isotope data, mineral composition and abundance data, and consideration of mineral textures is used to link assimilation of surface-derived Martian sulfate to oxidation of nakhlite melts. The magnitudes of the mass independent sulfur isotope signatures (negative Δ33S) and the abundance of sulfide minerals accounts for much of the added oxygen implied by the occurrence of abundant skeletal titanomagnetite in the MIL pairs. Assimilation and reduction of sulfate amounts equivalent to that from 10′s of centimeters of Martian sediment are required to account for an oxidation front extending ∼1 m into the flow, a position previously proposed for MIL 03346, and implies a position at the bottom, rather than the top of a nakhlite flow. A similar positional and amount constraint is required for an alternative path for assimilation of sulfate from sulfate-rich brine. Assimilation and reduction of sulfate is therefore inferred to play a critical role in establishing both the enrichment in skeletal titanomagnetite within the lower portion of the nakhlite pile and the large Δ33S anomalies of the MIL pairs. Other nakhlites with smaller Δ33S anomalies and less titanomagnetite would occupy positions farther away from the source of sulfate.

Reactions of sulfur and oxygen containing anions with nitrogen and oxygen atoms: A comparative study

Sulfur‒containing anions are expected to exist in molecular clouds and other astrochemical environments due to the relative abundance of sulfur and the predicted stability of the anions. Furthermore, nitrogen and oxygen atoms are of high abundance in the interstellar medium. Therefore, reactions of nitrogen and oxygen atoms with small sulfur‒containing anions, SCN−, CH3COS−, C6H5COS−, −SCH2COOH, C6H5S−, and related oxygen‒containing anions, OCN−, CH3COO−, C6H5COO−, HOCH2COO−, C6H5O−, have been studied both experimentally and computationally. The experimental results show that none of the studied anions react with nitrogen atoms. All of the studied anions with the exception of OCN− react with oxygen atoms, and the reaction channels are more diverse than those for the previously studied reactions with hydrogen atoms. In addition to the associative electron detachment (AED) channel, some ionic products such as CN−, CH3COO−, C6H5COO−, HO− and S− were observed. A sulfur‒oxygen exchange channel was observed in the reactions of oxygen atoms with CH3COS−, C6H5COS− and C6H5S− anions. A sulfur abstraction channel was observed in the reactions of oxygen atoms with SCN− and −SCH2COOH anions. The rate constants for reactions between sulfur‒containing anions and oxygen atoms are found to be generally higher than for the related oxygen‒containing anions. Density functional theory calculations were conducted to provide insight into the experimental results.

Ultrahigh Performance All Solid-State Lithium Sulfur Batteries: Salt Anion's Chemistry-Induced Anomalous Synergistic Effect.

With a remarkably higher theoretical energy density compared to lithium-ion batteries (LIBs) and abundance of elemental sulfur, lithium sulfur (Li-S) batteries have emerged as one of the most promising alternatives among all the post LIB technologies. In particular, the coupling of solid polymer electrolytes (SPEs) with the cell chemistry of Li-S batteries enables a safe and high-capacity electrochemical energy storage system, due to the better processability and less flammability of SPEs compared to liquid electrolytes. However, the practical deployment of all solid-state Li-S batteries (ASSLSBs) containing SPEs is largely hindered by the low accessibility of active materials and side reactions of soluble polysulfide species, resulting in a poor specific capacity and cyclability. In the present work, an ultrahigh performance of ASSLSBs is obtained via an anomalous synergistic effect between (fluorosulfonyl)(trifluoromethanesulfonyl)imide anions inherited from the design of lithium salts in SPEs and the polysulfide species formed during the cycling. The corresponding Li-S cells deliver high specific/areal capacity (1394 mAh gsulfur-1, 1.2 mAh cm-2), good Coulombic efficiency, and superior rate capability (∼800 mAh gsulfur-1 after 60 cycles). These results imply the importance of the molecular structure of lithium salts in ASSLSBs and pave a way for future development of safe and cost-effective Li-S batteries.

Bacterial community structure analysis of a hot spring soil by next generation sequencing of ribosomal RNA

In the present study the whole bacterial community structure of Tapovan hot spring soil located in the state of Uttarakhand, India was analysed through next generation sequencing. The hot spring soil is slightly alkaline in nature with abundance of sulphur. The spring soil was rich in various metallic and non-metallic elements required for bacterial survival. The community was found to comprise of 14 bacterial phyla with representation of members belonging to Firmicutes, Proteobacteria, Thermi, Bacteroidetes, Aquificae, Actinobacteria, chloroflexi, TM7, Fusobacteria etc. At the genus level Bacillus, Pseudomonas, Symbiobacterium, Thermus, Geobacillus, Anoxybacillus were found in abundance as compared to other genera like Flavobacterium, Ureibacillus, Clostridium, Meiothermus, Acinetobacter, Desulfotomaculum and Rheinheimera.

Neon, sulphur, and argon abundances of planetary nebulae in the sub-solar metallicity Galactic anti-centre

Context.Spectra of planetary nebulae show numerous fine structure emission lines from ionic species, enabling us to study the overall abundances of the nebular material that is ejected into the interstellar medium. The abundances derived from planetary nebula emission show the presence of a metallicity gradient within the disk of the Milky Way up to Galactocentric distances of ~10 kpc, which are consistent with findings from studies of different types of sources, including H II regions and young B-type stars. The radial dependence of these abundances further from the Galactic centre is in dispute.Aims.We aim to derive the abundances of neon, sulphur and argon from a sample of planetary nebulae towards the Galactic anti-centre, which represent the abundances of the clouds from which they were formed, as they remain unchanged throughout the course of stellar evolution. We then aim to compare these values with similarly analysed data from elsewhere in the Milky Way in order to observe whether the abundance gradient continues in the outskirts of our Galaxy.Methods.We have observed 23 planetary nebulae at Galactocentric distances of 8–21 kpc withSpitzerIRS. The abundances were calculated from infrared emission lines, for which we observed the main ionisation states of neon, sulphur, and argon, which are little affected by extinction and uncertainties in temperature measurements or fluctuations within the planetary nebula. We have complemented these observations with others from optical studies in the literature, in order to reduce or avoid the need for ionisation correction factors in abundance calculations.Results.The overall abundances of our sample of planetary nebulae in the Galactic anti-centre are lower than those in the solar neighbourhood. The abundances of neon, sulphur, and argon from these stars are consistent with a metallicity gradient from the solar neighbourhood up to Galactocentric distances of ~20 kpc, albeit with varying degrees of dispersion within the data.

Surface Functionalization of Carbon Architecture with Nano‐MnO2 for Effective Polysulfide Confinement in Lithium–Sulfur Batteries

Li-S batteries have received tremendous attention owing to their high theoretical capacity (1672 mA h g-1 ), sulfur abundance, and low cost. However, main systemic issues, associated with polysulfide shuttling and low Coulombic efficiency, hinder the practical use of the sulfur electrode in commercial batteries. Herein, we demonstrate an effective strategy of decorating nano-MnO2 (less than 10 wt %) onto the sulfur reservoir to capture the out-diffused polysulfides through chemical interaction and thereby improve the electrochemical performance of the sulfur electrode without increasing the mass burden of total battery configuration. Pistachio shell-derived sustainable carbon (PC) was employed as effective sulfur containers owing to its structural characteristics (interconnected macro channels and micropores). With the aids of the structural benefits of the PC scaffold and the uniform decoration of nano-MnO2 , polysulfide shuttling was significantly suppressed and the cycling performance of the sulfur cathode was dramatically improved over 250 cycles.

Thermal alteration of biomarkers in the presence of elemental sulfur and sulfur-bearing minerals during hydrous and anhydrous pyrolysis

Although elemental sulfur and sulfur-bearing minerals are not the main constituents of sedimentary rock, they are still important for the formation and destruction of biomarkers. In this study, a bitumen of Sichuan Basin mudstone with abundant biomarkers was separately pyrolyzed (under both hydrous and anhydrous conditions) with elemental sulfur (S0) and sulfur-bearing minerals (including pyrite, ferrous sulfate, and ferric sulfate) at various temperatures (300, 330 and 350 °C). The results show that the effects of different forms of sulfur on the evolution of biomarkers vary. Pyrite (FeS2) had only a slight influence on the characteristics of the biomarkers during anhydrous and hydrous pyrolysis. On the other hand, the presence of S0, ferrous sulfate (FeSO4) and ferric sulfate (Fe2(SO4)3) promoted the thermal cracking of the biomarkers and changed the biomarker distributions under anhydrous conditions. The extent of biomarker thermal alterations decreased in the following order: S0 > Fe2(SO4)3 > FeSO4 > FeS2. Additionally, the presence of water seemed to promote the effects of the sulfur additive on the changes in biomarker compositions, but this did not change their raking in terms of influence. The elemental sulfur alteration of the biomarkers increased with pyrolysis temperature (simulated maturity) and the abundance of elemental sulfur in the sample. The results obtained offer new insights into how biomarkers evolve when elemental sulfur and sulfur-bearing minerals are present.

Sulfur isotope signatures of eucrites and diogenites

High precision sulfur isotope data on eight eucrites and two diogenites are reported to explore the provenance of sulfur and processes that affected the sulfur isotope composition and sulfur abundance within the HED (Howardite, Eucrite, Diogenite) parent body (Asteroid 4 Vesta) or parent bodies for eucrite-like meteorites. Sulfur isotope values for a subset of six of the eucrites (EET 90020, PCA 82502, BTN 00300, MIL 11290, QUE 97014, and Sioux County) and two diogenites (Johnstown and Shalka) converge on a singular sulfur isotope composition, yielding a mean δ34S of 0.26 ± 0.17‰ (2 SD), Δ33S of 0.010 ± 0.007‰ (2 SD), and Δ36S of −0.22 ± 0.21‰ (2 SD). The variances on these mean values can be entirely accounted for by analytical uncertainties. The homogenous positive Δ33S for these samples suggests that sulfur in Asteroid 4 Vesta has a Δ33S of 0.010 ± 0.002‰ (2 SE) which is consistent with the occurrence of a process that allowed for promoted-isotopic-exchange within the parent body to homogenize Δ33S. This process was previously recognized in the homogenous Δ17O composition that has been linked to large-scale silicate melting and mixing. The positive δ34S of this group of samples is attributed to fractionations associated with sulfur loss, and the homogeneity of sulfur isotopes suggests that this loss predates the mixing event. The sulfur isotope data alone do not differentiate whether this loss occurred prior to or post core formation, or even prior to accretion.Two eucrites (GRA 98098 and CMS 04049) yield isotopic compositions that are distinct from this mean for δ34S, and in the case of CMS 04049, for Δ33S as well. GRA 98098 yields δ34S of 0.81 ± 0.18‰ (2 σest, estimated external precision), Δ33S of 0.010 ± 0.008‰ (2 σest) and Δ36S of 0.01 ± 0.34‰ (2 σest). CMS 04049 yields δ34S of −0.22 ± 0.18‰ (2 σest), Δ33S of 0.024 ± 0.008‰ (2 σest), and Δ36S of −0.17 ± 0.34‰ (2 σest). The more positive δ34S of GRA98098 suggests fractionation of sulfur (34S/32S) by a combination of parent body processes that may be linked to evaporation. The more positive Δ33S and the negative δ34S of CMS 04049 suggests that this meteorite may be from another ‘Vesta-like’ parent body.