Organic Sulfur Compounds Research Articles

Malodorous gases production from food wastes decomposition by indigenous microorganisms

Volatile organic compounds (VOCs) produced during the degradation of food wastes may harm to the health of people and create annoyance in adjacent communities. In this work, the VOCs emitted from the decomposition food wastes including fruit, meat and vegetable, and their microbial communities were measured in three individual 57-L reactors for 61 days. Total of 232.8, 373.5, and 191.1 μg·kg−1·h−1 VOCs with oxygenated VOCs (57.6%), volatile organic sulfur compounds (VOSCs, 58.6%) and VOSCs (54.9%) as the main group were detected during fruit, meat and vegetable fermentation, respectively. 2-Butanone (55.1%) and ethyl acetate (13.8%) were the two most abundant VOCs from fruit wastes, while dimethyl sulfide (68.0 and 26.6%) and dimethyl disulfide (89.2 and 10.1%) were in vegetable and meat wastes. The predominant Firmicutes represented 93.0–99.9% of the bacterial communities of meat decomposition, while Firmicutes and Proteobacteria were the dominant phyla throughout the fruit digestion process. Proteobacteria (16.9%–83.6%) was the dominant phylum in vegetable wastes, followed by Bacteroidetes, Firmicutes, and Actinobacteria. Malodorous VOCs emissions were highly affected by microbial activity, the abundant Weissella, Leuconostoc and Enterobacteriaceae in vegetable wastes showed correlation with carbon disulfide and dimethyl sulfide, while dominant Peptococcus, Bacteroides, Lactobacillales and Peptoniphilus in meat wastes was related to dimethyl disulfide. Overall, significant differences and correlation between VOCs emission profiles and bacterial communities among different food wastes decomposition were observed. These data contribute to a more comprehensive understanding the relationship between microbial community dynamics and malodorous VOCs emission.

Unique Solid Phase Microextraction Sampler Reveals Distinctive Biogeochemical Profiles among Various Deep-Sea Hydrothermal Vents

Current methods for biochemical and biogeochemical analysis of the deep-sea hydrothermal vent ecosystems rely on water sample recovery, or in situ analysis using underwater instruments with limited range of analyte detection and limited sensitivity. Even in cases where large quantities of sample are recovered, labile dissolved organic compounds may not be detected due to time delays between sampling and preservation. Here, we present a novel approach for in situ extraction of organic compounds from hydrothermal vent fluids through a unique solid phase microextraction (SPME) sampler. These samplers were deployed to sample effluent of vents on sulphide chimneys, located on Axial Seamount in the North-East Pacific, in the Urashima field on the southern Mariana back-arc, and at the Hafa Adai site in the central Mariana back-arc. Among the compounds that were extracted, a wide range of unique organic compounds, including labile dissolved organic sulfur compounds, were detected through high-resolution LC-MS/MS, among which were biomarkers of anammox bacteria, fungi, and lower animals. This report is the first to show that SPME can contribute to a broader understanding of deep sea ecology and biogeochemical cycles in hydrothermal vent ecosystems.

Formation, nutritional value, and enhancement of characteristic components in black garlic: A review for maximizing the goodness to humans.

Black garlic (BG) is essentially a processed food and obtained through the transformation of fresh garlic (FG) (Allium sativum L.) via a range of chemical reactions (including the Maillard reaction) and microbial fermentation. This review provides the up-to-date knowledge of the dynamic and complicated changes in major components during the conversion of FG to BG, including moisture, lipids, carbohydrates (such as sugars), proteins, organic acids, organic sulfur compounds, alkaloids, polyphenols, melanoidins, 5-hydroxymethylfurfural, vitamins, minerals, enzymes, and garlic endophytes. The obtained evidence confirms that BG has several advantages over FG in certain product attributes and biological properties (especially antioxidant activity), and the factors affecting the quality of BG include the type and characteristics of FG and processing technologies and methods (especially pretreatments, and processing temperature and humidity). The interactions among garlic components, and between garlic nutrients and microbes, as well as the interplay between pretreatment and main manufacturing process, all determine the sensory and nutritional qualities of BG. Before BG is marketed as a novel snack or functional food, more research is required to fill the knowledge gaps related to quantitative monitoring of the changes in metabolites (especially those taste-active and/or biological-active substances) during BG manufacturing to maximize BG's antioxidant, anticancer, antiobesity, anti-inflammatory, immunostimulatory, anti-allergic, hepatoprotective, cardioprotective and oxidative stress-/hangover syndrome-reducing functions, and beneficial effects on memory/nervous systems. Assessments of the quality, efficacy, and safety of BG should be performed considering the impacts of BG production conditions, postproduction handling, and intake methods.

Preparation of allicin-whey protein isolate conjugates: Allicin extraction by water, conjugates' ultrasound-assisted binding and its stability, solubility and emulsibility analysis.

The instability of allicin makes it easily decomposed into various organic sulfur compounds, resulting in significant decrease in biological activity. In this study, allicin was firstly extracted with water, then bound with whey protein isolates (WPI) which were pretreated by ultrasound to form conjugates, and the stability, water solubility and emulsibility of conjugates were as well investigated. The research results showed that there were no significant differences in the extraction yields of allicin from water, 40% and 80% ethanol. Appropriate frequency (20/40kHz), power (50W/L) and time (20min) of ultrasonic pretreatments significantly increased (P<0.05) the sulfhydryl groups content of WPI by 35.05% over control, causing improvement in binding ability of protein to allicin. The binding process of allicin-WPI displayed good fit with Elovich kinetic model (R2=0.9781). The mass retention rate of the conjugates (in 60% combination rate) with ultrasonic pretreating kept at 95.97% after 14days of storage at 25°C, whereas allicin's mass retention rate was only 61.79% at same storage condition. The water solubility of the prepared conjugates was significantly higher than allicin. And with optimal condition ultrasonic pretreatment of WPI, the conjugates showed the highest emulsifying capacity and emulsion stability (49.56m2/g, 10.06min). In conclusion, the ultrasonically pretreated allicin-WPI conjugates exhibited better stability, water solubility and emulsifying properties compared to allicin, this expands the application field of allicin.

Integration of Biological Networks for Acidithiobacillus thiooxidans Describes a Modular Gene Regulatory Organization of Bioleaching Pathways.

Acidithiobacillus thiooxidans is one of the most studied biomining species, highlighting its ability to oxidize reduced inorganic sulfur compounds, coupled with its elevated capacity to live under an elevated concentration of heavy metals. In this work, using an in silico semi-automatic genome scale approach, two biological networks for A. thiooxidans Licanantay were generated: (i) An affinity transcriptional regulatory network composed of 42 regulatory family genes and 1,501 operons (57% genome coverage) linked through 2,646 putative DNA binding sites (arcs), (ii) A metabolic network reconstruction made of 523 genes and 1,203 reactions (22 pathways related to biomining processes). Through the identification of confident connections between both networks (V-shapes), it was possible to identify a sub-network of transcriptional factor (34 regulators) regulating genes (61 operons) encoding for proteins involved in biomining-related pathways. Network analysis suggested that transcriptional regulation of biomining genes is organized into different modules. The topological parameters showed a high hierarchical organization by levels inside this network (14 layers), highlighting transcription factors CysB, LysR, and IHF as complex modules with high degree and number of controlled pathways. In addition, it was possible to identify transcription factor modules named primary regulators (not controlled by other regulators in the sub-network). Inside this group, CysB was the main module involved in gene regulation of several bioleaching processes. In particular, metabolic processes related to energy metabolism (such as sulfur metabolism) showed a complex integrated regulation, where different primary regulators controlled several genes. In contrast, pathways involved in iron homeostasis and oxidative stress damage are mainly regulated by unique primary regulators, conferring Licanantay an efficient, and specific metal resistance response. This work shows new evidence in terms of transcriptional regulation at a systems level and broadens the study of bioleaching in A. thiooxidans species.

Quality changes in oil marinades used for flavoring of meat

AbstractMeat semi-finished products that are portioned or not, meat with the addition of a different composition of spices and oil are a common element of the commercial offer in the convenient ready to cook food segment. During the refrigeration storage in this complex system of meat, oil and spices, there is a number of physicochemical changes, including hydrolytic and oxidative changes of the oil(1). The products of these reactions become integral components of the meat subjected to heat treatment. As a result of heating, secondary oxidation products of lipids may be formed which constitute a serious health risk(2). The study was aimed at determination of the effect of spices containing antioxidants and sulfur-organic compounds on hydrolytic and oxidative changes in the oil that formed the base of the marinade in which meat was kept. Pork neck was minced and formed into burgers (250 g), rapeseed oil (120 g) and spices (5 g) were used. Four research groups were analyzed meat / oil / spices system with rosemary, oregano, garlic or onion. Oil samples were collected on the third, fifth and eighth day of refrigerated storage. The control sample was the oil from the meat / oil system only. The quality of the oil was evaluated on the basis of the acid value, peroxide value and TBARS index. In the oil with onion, garlic, rosemary and oregano the hydrolytic changes on the 8th day of storage were significantly lower compared to the control. On the basis of the average peroxide value in oil marinades with the addition of rosemary and oregano, significantly lower values of this indicator were found when using rosemary (3.61 meq O2/kg) in comparison with oregano (6.01 meq O2/kg). The average of TBARS index in marinade with onions and garlic was lower by 31% and 48%, respectively. Also the use of rosemary and oregano was effective in blocking the formation of secondary oxidation products (rosemary even three times higher than that of oregano).

Activation of SOD-3 is involved in the antioxidant effect of a new class of β-aryl-chalcogenium azide compounds in Caenorhabditis elegans.

Organic selenium, tellurium and sulfur compounds have been studied due to their pharmacological properties. For instance, the β-aryl-chalcogenium azide compounds have demonstrated antitumoral action in vitro. However, yet no pharmacological actions of this class of compounds were determined in vivo. Caenorhabditis elegans is a nematode that presents innumerable advantages in relation to mammalian models, such as having a small and transparent body, which allows the visualization of its internal anatomy, besides short life and low cost. Based on that, the aim of this work was to investigate the pharmacological and toxicological properties of β-aryl-chalcogenium azide compounds in C. elegans. As well, to evaluate the capacity of organochalcogenium compounds to repair oxidative damage induced by hydrogen peroxide and the possible mechanism of action of these compounds using CF1553 transgenic strain with superoxide dismutase (SOD-3) tagged with GFP. Our results showed that β-aryl-chalcogenium azide have low toxicity in wild-type worms and the pre-treatment protected against the damage induced by hydrogen peroxide at higher tested concentration. Associated with this, we observed that this protection is due in part to the increased expression of the antioxidant enzyme SOD-3. In conclusion, β-aryl-chalcogenium azide compounds caused low toxicity and induced stress-resistance by modulating SOD-3 expression in C. elegans.

СІРКООРГАНІЧНІ СПОЛУКИ КОКСОВОГО ГАЗУ ТА ЇХ ВКЛАД У ВИКИДИ ДІОКСИДУ СІРКИ З ДИМОВИХ ТРУБ КОКСОВИХ БАТАРЕЙ

The article touches upon the problem of cleaning of the coke oven gas from sulfur compounds, which is relevant in connection with the requirements for reducing of the sulfur dioxide emissions into the atmosphere and ensuring of the environmental safety of production in general. At present, the sulfur dioxide emissions from coke-chemical plants account for about 20 % of the total emissions of pollutants from coke ovens and are calculated from the concentration of hydrogen sulfide in coke oven gas after its purification before feeding to coke oven batteries heating systems. However, in addition to hydrogen sulfide, coke oven gas also contains organosulfur compounds such as carbon disulfide (CS2), carbon oxysulfide (COS), thiophene (C4H4S), mercaptans, etc. The authors of the article carried out a study to determine the content of organic sulfur compounds in the original and purified coke oven gas, as well as the contribution of these substances to sulfur dioxide emissions from the smokestacs of coke oven batteries. The calculation has been performed of the additional volume of sulfur dioxide, which is formed due to the combustion of organosulfur compounds of coke oven gas during its combustion in the heating system of coke ovens. It has been found that under the condition of complete conversion of organic sulfur compounds into sulfur dioxide during the combustion of coke oven gas in the heating system of coke ovens, the concentration of sulfur dioxide in flue gases can be approximately 25.0-35.0 mg/m3 (in recount on 5 % oxygen content in flue gases). It has been also shown that the share of emissions of the sulfur dioxide formed as a result of the combustion of hydrogen sulfide in coke oven gas is 90-95 %, and that formed as a result of combustion of the organic sulfur compounds is 5-10 %, even if they are completely transformed into the sulfur dioxide. It has been concluded that it is legitimate to calculate the volume of sulfur dioxide emissions based on the concentration of hydrogen sulfide in purified coke oven gas, supplied as an energy carrier to the heating system of coke ovens.

Multi-air-pollutant removal by using an integrated system: Key parameters assessment and reaction mechanism

How to cost-efficiently and cooperatively remove SO2, NO and Hg0 in flue gas is a hot topic in the field of air pollution control. This work developed an integrated system that consists of a dual-absorption system and a vapor oxidation system, in which Na2CO3 and H2O2/Na2S2O8 were used as the absorbent and oxidant. The results indicated that the efficiencies of SO2 removal and NO conversion reached 99.5% and 93% respectively. Rising the vaporization temperature and decreasing the pH of H2O2/Na2S2O8 could facilitate the NO conversion. The spent Na2CO3 after desulfurization was demonstrated to be a good absorbent for NO2 removal. The best conditions of pH and temperatures for the dual-absorber were determined as 10/8 and 60/60 °C, respectively. The presence of 1000 mg/m3 SO2 and 300 mg/m3 NO favored the Hg0 removal. TMT-15, an organic sulfur compound, was demonstrated to be useful in retaining Hg2+, with an efficiency of 92%. According to the analyses of electron spin resonance (ESR), ion chromatography (IC), atom fluorescence spectrometry (AFS) and X-ray photoelectron spectroscopy (XPS), SO4− and HO were proved to be the key radicals, and the existing forms of N- and Hg- species in the product were identified as NaNO2/NaNO3 and HgCl2.

Effect of dimethyl disulfide on the sulfur formation and microbial community composition during the biological H2S removal from sour gas streams

Removal of organic and inorganic sulfur compounds from sour gases is required because of their toxicity and atmospheric pollution. The most common are hydrogen sulfide (H2S) and methanethiol (MT). Under oxygen-limiting conditions about 92 mol% of sulfide is oxidized to sulfur by haloalkaliphilic sulfur-oxidizing bacteria (SOB), whilst the remainder is oxidized either biologically to sulfate or chemically to thiosulfate. MT is spontaneously oxidized to dimethyl disulfide (DMDS), which was found to inhibit the oxidation of sulfide to sulfate. Hence, we assessed the effect of DMDS on product formation in a lab-scale biodesulfurization setup. DMDS was quantified using a newly, in-house developed analytical method. Subsequently, a chemical reaction mechanism was proposed for the formation of methanethiol and dimethyl trisulfide from the reaction between sulfide and DMDS. Addition of DMDS resulted in significant inhibition of sulfate formation, leading to 96 mol% of sulfur formation. In addition, a reduction in the dominating haloalkaliphilic SOB species, Thioalkalivibrio sulfidiphilus, was observed in favor of Thioalkaibacter halophilus as a more DMDS-tolerant with the 50 % inhibition coefficient at 2.37 mM DMDS.

Aromatic hydrocarbons provide new insight into carbonate concretion formation and the impact of eogenesis on organic matter

Investigations of aromatic biomarkers extracted from carbonate concretions can contribute to characterization of the enhanced microbial activity that mediates carbonate concretion formation. This microbial footprint can be further inferred from the stable isotopic values of carbonate (δ13C) and pyrite (δ34S). Here, we used a combination of GC–MS and GC × GC-ToF-MS to compare the aromatic fractions of two Toarcian carbonate concretions from the H. falciferum ammonite zone of the Posidonia Shale (SW-Germany) and their host sediment. The results revealed that n-alkylated and phytanyl arenes were enhanced in the concretions, relative to the host sediment. These findings support a very early diagenetic (eogenetic) microbial source for alkylated and phytanyl arenes derived from the microbial ecosystem mediating concretion formation. In contrast, aromatic compounds formed by thermal maturation (e.g. polycyclic aromatic hydrocarbons, aromatic steroids, organic sulphur compounds) remained invariant in host rock and concretion samples. When combined with bulk sediment and concretion properties, the distribution of aromatic compounds indicates that eogenetic microbial activity upon concretion growth does not diminish organic matter quality.

Dimethylated sulfur production in batch cultures of Southern Ocean phytoplankton

Dimethylsulfoniopropionate (DMSP) is a ubiquitous organic sulfur compound that underpins sulfur cycling in the marine environment and is the precursor to the climatically active gas dimethylsulfide (DMS). Modelling studies have identified the Southern Ocean as a DMS hot spot during summer, yet except for the bloom forming haptophyte Phaeocystis, little is known about sulfur production by other important members of the marine microbial community. Here, we measured DMSP concentrations and DMSP lyase activity (DLA), with corresponding carbon, nitrogen and Chl a content, in 15 species of Antarctic phototrophic phytoplankton (14 microalgae species and one cyanobacterium) and one phagotrophic flagellate. We found that 11 of the 16 species were able to produce DMSP and eight possess DLA. DMSP content ranged from 0.06 to 73 fmol cell−1 and estimated DMSP production rates ranged from 0.008 to 12.42 fmol cell−1 day−1. As expected, Phaeocystis was amongst the highest producers, however, contrary to expectation DMSP concentrations were high in several pennate diatom species, with intracellular concentrations between 1.85 and 46.6 mM. Here we present the first evidence that the cyanobacterium Synechococcus may be a DMSP producer, with the potential to contribute significantly to the DMSP pool. This study has provided the first analysis of DMSP production and DLA in a suite of phototrophic and phagotrophic species isolated from Antarctica, revealing the variability in DMSP concentrations across multiple strains and within genera and delivered new evidence for potential DLA in diatoms.

N-METHYLPYRROLIDONE – SELECTIVE SOLVENT FOR OXIDATIVE DESULFURIZATION OF LIGHT GASOLINE FRACTIONS

The extraction of various sulfur-containing compounds occurring in the oil and condensate fractions using solutions based on N-methylpyrrolidone was studied. The extracts can later be used in the organic/electrochemical synthesis of valuable organosulfur compounds. By the example of a model mixture, the solvent is shown to be selective to various classes of organic sulfur compounds: thiols, mono-, di-, and trisulfides. It is established that the solvent exhibits the greatest affinity to aromatic sulfur compounds. The extraction degree increases from mono- to di- and trisulfide. In the case of aliphatic thiols, a decrease in the degree of extraction is observed with an increase in the length of the hydrocarbon group. The optimal parameters of extraction with mixtures based on N-methylpyrrolidone for light gasoline fractions BPT-90 °C and BPT-120 °C were set: the temperature – 35 °C, the ratio solvent - feedstock is 1 to 1. In the series of different mixtures of solvents, a selective solvent based on dimethyl carbonate (5% by weight) showed the highest efficiency. At the same time, the highest raffinate yield with a moderate total sulfur content is observed for the solvent with H2O (5% by weight). A multi-stage extraction of sulfur components from gasoline fractions using the mixture N-methylpyrrolidone with H2O allowed reducing the content of organic sulfur compounds by 7-10 times. A combined process based on the extraction of thiols from model mixtures and its oxidation by o-benzoquinones is proposed. Unlike the more aggressive oxidizing agents o-benzoquinones depending on the structure ensure the utilization of thiols to thioethers or disulfides.

Unprecedented DMSP Concentrations in a Massive Dinoflagellate Bloom in Monterey Bay, CA

AbstractThe organic sulfur compound dimethylsulfoniopropionate (DMSP) is synthesized by numerous species of marine phytoplankton, and its volatile degradation products are a major source of biogenic sulfur to the atmosphere. A massive bloom of the dinoflagellate Akashiwo sanguinea occurred in Monterey Bay, CA, USA, in the fall of 2016 and led to exceptionally high seawater DMSP concentrations that peaked at 4,240 nM. Bacterial consumption rates showed that only a small fraction of the DMSP standing stock flowed through the dissolved DMSP pool per day, contributing to the high DMSP concentrations and creating conditions conducive to production of dimethylsulfide (DMS). Conservative calculations of DMS yield from this persistent A. sanguinea bloom suggest substantial regional‐scale inputs of DMS‐sulfur to the atmosphere. Other recently reported major coastal blooms of A. sanguinea, along with indications that this species may benefit from climate change conditions, reveal a mechanism that could alter oceanic contributions to atmospheric sulfur pools.

Application of carbonized ion exchange resin beads as catalyst support for gas phase hydrogenation processes

Carbonized ion exchange resin beads were prepared as catalyst for gas phase hydrogenation processes. Amberlite IR 120 polystyrene based sulfonated ion exchange beads were carbonized at 900 °C. The process of carbonization was monitored by FTIR combined thermogravimetric analysis. During the carbonization formed sulfur dioxide, carbon dioxide and organic compounds. The carbon pearls were used as catalyst support for Pd nanoparticles. The catalyst was characterized by scanning electron microscopy and X-ray diffractometry. The diameters of the palladium nanoparticles on the catalyst surface were between 15 and 50 nm, but bigger aggregates were also detected. The catalyst was tested during the gas phased heterogeneous catalytic hydrogenation of 1-butene. The hydrogenation process was followed by FTIR measurements, 93% conversion was reached after 10 min.

The Production and Fate of Volatile Organosulfur Compounds in Sulfidic and Ferruginous Sediment

AbstractVolatile organic sulfur compounds (VOSCs) link the atmospheric, marine, and terrestrial sulfur cycles in marine and marginal marine environments. Despite the important role VOSCs play in global biogeochemical sulfur cycling, less is known about how the local geochemical conditions influence production and consumption of VOSCs. We present a study of dimethyl sulfide (DMS), methanethiol (MeSH), and dimethylsulfoniopropionate (DMSP) in sulfide‐rich (sulfidic) and iron‐rich (ferruginous) salt marsh sediment from north Norfolk, UK. Initial results illustrate the importance of minimizing time between sampling in remote field locations and laboratory analysis, due to rapid degradation of VOSCs. With rapid analysis of sediment from different depths, we observe high concentrations of DMS, MeSH, and DMSP, with concentrations in surface sediment an order of magnitude higher than those in previous studies of surface water. We measure systematic differences in the concentration and depth distribution of MeSH and DMS between sediment environments; DMS concentrations are higher in ferruginous sediment, and MeSH concentrations are higher in sulfidic sediment. With repeated measurements over a short time period, we show that the degradation patterns for DMS and MeSH are different in the ferruginous versus sulfidic sediment. We discuss potential biogeochemical interactions that could be driving the observed differences in VOSC dynamics in ferruginous and sulfidic sediment.

Synthesis of Highly Unsaturated Organic Sulfur Compounds from 1,4-Dichlorobut-2-yne and Propane-1,3-dithiolate

The reaction of 1,4-dichlorobut-2-yne with propane-1,3-dithiolate was carried out for the first time. A mixture of cyclic (2-vinyl-1,4-dithiepan-2-ene) and linear (5,10-dithiatridec-1,12-diyne-3,10-diene) products was synthesized, in 30 and 15% yields, respectively.

Taste and odor compounds associated with aquatic plants in Taihu Lake: distribution and producing potential.

The odor problem caused by the decay of aquatic plants is widespread in many freshwater lakes. In this study, the spatial distributions of seven taste and odor (T&O) compounds (dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide, 2-methylisoborneol, geosmin, β-cyclocitral, and β-ionone) in the sediments and overlying water of the east of Taihu Lake were investigated. The effects of plant and physico-chemical parameters on the release of T&O compounds were also analyzed. The results showed that high concentrations of T&O compounds were detected in the area where Eichhornia crassipes was flourishing. Volatile organic sulfur compounds were not found in the water source area, which was not covered by aquatic plants. High plant biomass and aquiculture activities might increase the release of the taste and odor compounds. The correlation between the concentrations of odorous compounds and nutrients in the sediment was also analyzed. The production of odorants was positively correlated with the nitrogen, and they may migrate from sediment to overlying water. The result suggested that controlling the plant density and aquaculture activities could reduce the release of odorous compounds.

The source of sulfate in brachiopod calcite: Insights from μ-XRF imaging and XANES spectroscopy

Geochemical signatures preserved in sedimentary carbonate strata are often used as archives for paleoenvironmental reconstructions. However, diagenetic overprinting and/or muting of primary geochemical signatures complicates the interpretation of these data. To avoid this issue, geochemical techniques strive to target unaltered (or minimally altered) carbonate components. The multi-layer low-Mg calcite shell composition of articulate brachiopods are often the target in such studies because they are commonly more robust to recrystallization than the shells of other biomineralizers. Here, we have combined S K-edge μ-XRF imaging, XANES spectroscopy and petrography to determine the source of sulfate in the calcite lattice (carbonate-associated sulfate; CAS) of ancient and extant brachiopods, in order to establish their suitability for use in reconstructing seawater sulfate δ34S throughout the Phanerozoic. Both the extant brachiopod Terebratalia transversa and fossil brachiopods display intra-specimen variability in sulfate abundance parallel to the primary fabric, likely corresponding to variations in growth rate. XANES spectroscopy identifies a majority of the sulfate as inorganic. Additionally, XANES spectroscopy detected low abundances of both reduced and oxidized organic sulfur species (thiol, thioether, sulfoxide and sulfate esters) in all T. transversa samples and lesser abundances in a few of the fossil brachiopods. In T. transversa, inorganic sulfate and sulfate ester abundance increase towards the hinge of the valves. Bulk δ34SCAS of the samples containing the fossil brachiopods are consistently more positive than time-equivalent brachiopod-only values, likely reflecting a mixture of CAS signals from homogenization of carbonate components differentially affected by depositional environment and diagenesis. In contrast, bulk δ34SCAS of modern T. transversa is approximately 1‰ more positive than coeval seawater. Although organic sulfate esters are found within the brachiopod shells, they are only ever present as trace components. Our findings indicate that the vast majority of sulfate in brachiopod shells is inorganic, sourced from coeval seawater. This result supports the use of brachiopods as a potential archive for a faithful CAS record of seawater sulfate throughout the Phanerozoic. The characterization of in situ organic sulfur compounds in both extant and fossil brachiopods indicates the potential importance of various organic sulfur compounds in mineralogical determination (and therefore fossil preservation) and crystal orientation during brachiopod biomineralization throughout geologic time.

Synthesis and characterization of new sandwich-type polyoxometalate/nanoceramic nanocomposite, Fe2W18Fe4@FeTiO3, as a highly efficient heterogeneous nanocatalyst for desulfurization of fuel

Aiming deep oxidative desulfurization (ODS), Fe2W18Fe4@FeTiO3 composite was constructed as a new heterogeneous nanocatalyst on the basis of nanoceramic iron titanate (FeTiO3) and tetranuclear sandwich-type polyoxometalate (Na9K[(FeW9O34)2Fe4(H2O)2]·32H2O, abbreviated as Fe2W18Fe4). The results of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) analysis method indicated the successful composition of the materials. The XRD studies showed that the average crystallite size of the composite particles was estimated to be about 42.1 nm, which confirmed by the results of SEM. The catalytic performance of nanocatalyst was investigated in the ODS of real gasoline and model oils. The maximum sulfur removal efficiency was achieved at 35 °C after 60 min using in situ production of peroxyacetic acid (HOOAc) as an oxidant. The heterocyclic organic sulfur compounds such as thiophene (Th), benzothiophene (BT) and dibenzothiophene (DBT) were oxidized with the efficiency of 97, 98 and 99%, respectively. The kinetic studies revealed that the rate of the ODS process obeys the pseudo-first-order model. The superior catalytic activity of the Fe2W18Fe4@FeTiO3 was assessed by the formation of active metal-oxo-peroxo intermediate complexes during the oxidation step. Also, the nanocatalyst exhibited excellent activity and stability even after five times reuse. Therefore, the prepared Fe2W18Fe4@FeTiO3 composite was suggested as a potentially attractive heterogeneous nanocatalyst for application in the ODS process of gasoline.