Oxidation Of Sulfur Compounds Research Articles

Investigating the catalytic performance of polyoxometalate immobilized on magnetic chitosan in the oxidative desulfurization process

In this study, two types of polyoxometalate, one of Keggin type (PMo6W6O40) and the other of Dawson type (H11P2W13V5O62), were synthesized and fixed on chitosan with magnetic properties. The performance of synthesized catalysts was evaluated on the efficiency of removing aromatic sulfur compounds from the fuel model by the oxidative desulfurization method. Factors affecting the oxidation of sulfur compounds, such as reaction temperature, catalyst dosage, reaction time, and the ratio of oxidant to sulfur, were investigated to find the optimal conditions. The presence of Fe3O4 magnetic nanoparticles in the catalyst leads to the ease of separation from the petroleum model. The magnet-separated catalyst could be recycled for 5 catalytic cycles without significantly reducing removal efficiency.

Arcobacteraceae are ubiquitous mixotrophic bacteria playing important roles in carbon, nitrogen, and sulfur cycling in global oceans.

Mixotrophy is an important trophic strategy for bacterial survival in the ocean. However, the global relevance and identity of the major mixotrophic taxa remain largely elusive. Here, we combined phylogenetic, metagenomic, and metatranscriptomic analyses to characterize ubiquitous Arcobacteraceae based on our deep-sea in situ incubations and the global data. The phylogenomic tree of Arcobacteraceae is divided into three large clades, among which members of clades A and B are almost all from terrestrial environments, while those of clade C are widely distributed in various marine habitats in addition to some terrestrial origins. All clades harbor genes putatively involved in chitin degradation, sulfide oxidation, hydrogen oxidation, thiosulfate oxidation, denitrification, dissimilatory nitrate reduction to ammonium, microaerophilic respiration, and metal (iron/manganese) reduction. Additionally, in clade C, more unique pathways were retrieved, including thiosulfate disproportionation, ethanol fermentation, methane oxidation, fatty acid oxidation, cobalamin synthesis, and dissimilatory reductions of sulfate, perchlorate, and arsenate. Within this clade, two mixotrophic Candidatus genera represented by UBA6211 and CAIJNA01 harbor genes putatively involved in the reverse tricarboxylic acid pathway for carbon fixation. Moreover, the metatranscriptomic data in deep-sea in situ incubations indicated that the latter genus is a mixotroph that conducts carbon fixation by coupling sulfur oxidation and denitrification and metabolizing organic matter. Furthermore, global metatranscriptomic data confirmed the ubiquitous distribution and global relevance of Arcobacteraceae in the expression of those corresponding genes across all oceanic regions and depths. Overall, these results highlight the contribution of previously unrecognized Arcobacteraceae to carbon, nitrogen, and sulfur cycling in global oceans.IMPORTANCEMarine microorganisms exert a profound influence on global carbon cycling and ecological relationships. Mixotrophy, characterized by the simultaneous utilization of both autotrophic and heterotrophic nutrition, has a significant impact on the global carbon cycling. This report characterizes a group of uncultivated bacteria Arcobacteraceae that thrived on the "hot time" of bulky particulate organic matter and exhibited mixotrophic strategy during the in situ organic mineralization. Compared with clades A and B, more unique metabolic pathways were retrieved in clade C, including the reverse tricarboxylic acid pathway for carbon fixation, thiosulfate disproportionation, methane oxidation, and fatty acid oxidation. Global metatranscriptomic data from the Tara Oceans expeditions confirmed the ubiquitous distribution and extensive transcriptional activity of Arcobacteraceae with the expression of genes putatively involved in carbon fixation, methane oxidation, multiple sulfur compound oxidation, and denitrification across all oceanic regions and depths.

Sulfide oxidation by members of the Sulfolobales.

The oxidation of sulfur compounds drives the acidification of geothermal waters. At high temperatures (>80°C) and in acidic conditions (pH <6.0), oxidation of sulfide has historically been considered an abiotic process that generates elemental sulfur (S0) that, in turn, is oxidized by thermoacidophiles of the model archaeal order Sulfolobales to generate sulfuric acid (i.e. sulfate and protons). Here, we describe five new aerobic and autotrophic strains of Sulfolobales comprising two species that were isolated from acidic hot springs in Yellowstone National Park (YNP) and that can use sulfide as an electron donor. These strains significantly accelerated the rate and extent of sulfide oxidation to sulfate relative to abiotic controls, concomitant with production of cells. Yields of sulfide-grown cultures were ∼2-fold greater than those of S0-grown cultures, consistent with thermodynamic calculations indicating more available energy in the former condition than the latter. Homologs of sulfide:quinone oxidoreductase (Sqr) were identified in nearly all Sulfolobales genomes from YNP metagenomes as well as those from other reference Sulfolobales, suggesting a widespread ability to accelerate sulfide oxidation. These observations expand the role of Sulfolobales in the oxidative sulfur cycle, the geobiological feedbacks that drive the formation of acidic hot springs, and landscape evolution.

Coupled one-pot oxidative extractive desulfurization of a model fuel catalyzed by nanostructured-ZIF-67/Biomass-derived activated carbon composite

The simultaneous oxidation and extraction of refractory sulfur compounds, such as DBT, has emerged as one of the most efficient complementary procedures for the HDS process in achieving ultradeep desulfurization of fuels. In this paper, a bio-based activated carbon (AC) obtained from the waste of date palm bark has been utilized as an abundant, green, and low-cost support for synthesizing a stable metal-organic framework, zeolitic imidazolate framework-67 (ZIF-67), on its structure to reach a novel nanocomposite catalyst (AC/ZIF-67) for the removal of DBT from a model fuel through the extractive oxidative desulfurization method. The accuracy of the AC/ZIF-67 catalyst formation was comprehensively characterized using XRD, FTIR, FESEM, BET, and TGA analytical techniques. Subsequently, the newly synthesized nanocomposite catalyst was employed efficiently for removing DBT from a toluene solution, acting as a model fuel. The impact of various operating variables, i.e. catalyst dosage, the temperature of reaction, oxidant-to-sulfur (O/S) molar ratio, contact time, initial concentration of DBT, and volume of extraction solvent on the removal efficiency has been thoroughly investigated. The results revealed that employing only 25 mg of the AC/ZIF-67 catalyst could achieve a remarkably high efficiency of around 98 % after one hour oxidation of a 25 ppm DBT solution in the presence of TBHP, followed by extraction using acetonitrile. This was achieved while maintaining a constant temperature of 60 °C and an O/S ratio of 20. The obtained results confirm the potential application of ACs for supporting MOF catalysts in various catalytic processes such as desulfurization.

Peroxodicarbonate - a renaissance of an electrochemically generated green oxidizer.

The direct anodic conversion of alkali carbonates in aqueous media provides access to peroxodicarbonate, which is a safe to use and green oxidizer. Although first reports date back around 150 years, its low concentrations and limited thermal stability have consigned this reagent to oblivion. Boron-doped diamond anodes, novel electrolyser concepts for heat dissipation, and the mixed cation trick allow record breaking peroxodicarbonate concentrations >900 mM. The electrochemical generation of peroxodicarbonate was already demonstrated on a pilot scale. The inherent safety is ensured by the limited stability of the peroxodicarbonate solution, which decomposes under ambient conditions to oxygen and facilitates subsequent downstream processing. This peroxide has, in particular at higher concentrations, an unusual reactivity and seems to be an ideal reagent when peroxo-equivalents in combination with alkaline base are required. The conversions with peroxodicarbonate include the Dakin reaction, epoxidation, oxidation of amines (aliphatic and aromatic) and sulfur compounds, deborolative hydroxylation reactions, and many more. Since the base equivalents also represent the makeup chemical for pulping plants, peroxodicarbonate is an ideal reagent for the selective degradation of lignin to vanillin. Moreover, peroxodicarbonate can be used as a halogen-free bleaching agent. The emerging electrogeneration and use of this green platform oxidizer are surveyed for the first time.

Pool bio-oxidation and fitting analysis of low-grade arsenic-containing refractory gold ore

To overcome the limitations of geography, climate, and ore characteristics on the ore beneficiation process, bio-oxidation studies on low-grade arsenic-bearing refractory gold ore by pool leaching were carried out, as well as process fitting analysis. The gold particles are encapsulated by pyrite and arsenopyrite. After 60 days of bio-oxidation, the oxidation rates of arsenic, sulfur, and gold were 39%∼69%, 24%∼41%, and 49%∼83%, respectively. The inoculated Acidithiobacillus ferrooxidans, Ferroplasma acidiphilum, and Leptospirillum ferrodiazotrophum could all mediate the initial pyrite/arsenopyrite oxidation and the Fe2+ oxidation reaction, but only the former could mediate the subsequent sulfur compound oxidation. When compared to daily bacterial circulation and bacterial replacement every ten days, aeration improved the gold leaching rate by 14%∼22%. The Boltzmann model could fit both the arsenic and sulfur bio-oxidation, with model fit variances greater than 0.98. Based on the experimental and fitting results, the bio-oxidation cycle was determined to be 60 days, and the bio-oxidation mechanisms are summarized. This study has significant practical implications for the rational utilization of gold resources and provides theoretical and practical guidance for similar gold ores.

Deasphalting and oxidative desulfurization of heavy fuel oil followed by liquid-liquid extraction

ABSTRACT Heavy fuels usually contain very high amounts of complex sulfur compounds such as benzothiophenes and dibenzothiophenes leading to emission of SOx and sulfate particulate matter, which cause environmental problems such as air pollution and acid rains. Using oxidative desulfurization (ODS) process, sulfur compounds can be oxidized to sulfoxides and sulfones that can be removed using liquid-liquid extraction due to their high polarity, under mild conditions. In this study, oxidative desulfurization of a heavy fuel (Mazut, 3.1 wt% S) has been studied, with hydrogen peroxide as the oxidant and acetic acid as the catalyst. Applying ODS to Mazut commonly results in high viscosity and gum formation in the fuel. Therefore, in this study, a novel ODS procedure was developed and combined with an upgrading method to avoid this problem. The appropriate extraction solvent and the adequate solvent-to-fuel and oxidant to fuel ratios were also determined. The oxidized sulfur compounds were extracted by liquid-liquid extraction using a solvent, dimethylformamide (DMF). By using a pre-treatment method followed by a desulfurization process involving two rounds of oxidation and extraction, viscosity of fuel decreased about 87% and the sulfur content of the heavy fuel was decreased to 0.91 wt%, which means achieving 70.83% desulfurization.

Gasoline Fraction High-Efficient Sweetening by Gas Condensate Oxidation and Rectification

The results of the oxidative desulfurization process (combination of straight-run gasoline fraction and gas condensate oxidation with subsequent rectification) are presented. It is shown for the first time that it is possible to obtain a gasoline fraction with ultra-low sulfur content by oxidation and rectification of gas condensate. Optimum conditions have been selected for the process of sulfur compounds oxidation and subsequent rectification of gas condensate.

Bacterial community responses of the hydrothermal vent crab Xenograpsus testudinatus fed on microplastics

Microplastics (MPs) provide persistent contaminants in freshwaters and the oceans from anthropogenic sources worldwide. MP contamination in ecosystems has emerged as a global environmental issue. While increasing research focused on the ecological consequences of plastic pollution, health-related implications of plastic pollution have been somewhat overlooked. In this study, we evaluated the effects of polyethylene MP contamination on microbial, physical, and biochemical characteristics of the hydrothermal vent crab Xenograpsus testudinatus over a 7-day food exposure. Different concentrations (0%, 0.3%, 0.6%, and 1.0%) of polyethylene MPs were used for feed intake experiments. Oxford Nanopore Technologies’ full-length sequencing of the 16S rDNA gene was used to explore the changes of the microbial composition in vent crab tissues. At the phylum level, the content of Firmicutes significantly decreased in the digestive gland tissue. Furthermore, the predicted functions of genes in the microbial community were significantly influenced by MPs. In contrast, there were eight functions in gill and 11 functions in digestive gland tissues identified at low and high intake levels. The dominant functions of methylotrophy, dark thiosulfate oxidation, dark oxidation of sulfur compounds, aromatic hydrocarbon degradation, and aromatic compound degradation were significantly increased at high intake levels in the digestive gland. These findings indicate that MP ingestion causes not only a short-term decrease in energy intake for crustaceans but also a change in microbial communities and their functions. This study provided a first account on the toxicity of MPs in a hydrothermal vent crab to aid in the assessment of health risks provided by polyethylene MP to marine invertebrates.

Oxidation of sulfur compounds by oxo-Re(V) complexes containing salophen ligands through radical pathway

Oxidation, which converts sulfides into sulfoxides, is a widely used method for producing synthetic intermediates in various industries such as chemical, medicinal chemistry, and biology. In this study, we synthesized six oxo-rhenium(V) complexes, ReOClL1-6, using salophen ligands, which are different groups on the N-aryl backbone and phenolate arms, to develop selective and stable oxidation catalysts. Their structures were confirmed using 1H-, 13C- NMR, MALDI-TOF MS, and FTIR. In particular, optimum conditions have been investigated to overcome the synthetic challenge of the direct and selective production of oxidation products such as sulfoxides and/or sulfones. This was achieved with a short reaction time, low catalyst loading, and excellent yields. ReOClL1-6 complexes are active homogeneous catalysts for the oxidation of sulfur compounds (withtBuOOH to sulfoxide). ReOClL4 complex demonstrated superior catalytic performance compared to other complexes, owing to the electronic properties of the ligand scaffold. A general mechanism was proposed for the oxorhenium-catalyzed oxidation reaction of sulfur compounds with tBuOOH as the oxidant. The mechanism includes (i) coordination of tBuOOH to the catalyst, (ii) a homolytictBuO–OH bond cleavage by oxo-Re(V) complexleads totBuO and OH radicals, (iii) coordination of OOtBu radicals to the oxo-Re center, formed by OtBu radicals transferring a peroxy H atom in the presence of excess tBuOOH and (iv) a second homolytic bond cleavage of tBuOOORe species by oxo-Re(V) complexleads totBuO and O2− radicals.

Copiotrophy in a Marine-Biofilm-Derived Roseobacteraceae Bacterium Can Be Supported by Amino Acid Metabolism and Thiosulfate Oxidation.

Copiotrophic bacteria that respond rapidly to nutrient availability, particularly high concentrations of carbon sources, play indispensable roles in marine carbon cycling. However, the molecular and metabolic mechanisms governing their response to carbon concentration gradients are not well understood. Here, we focused on a new member of the family Roseobacteraceae isolated from coastal marine biofilms and explored the growth strategy at different carbon concentrations. When cultured in a carbon-rich medium, the bacterium grew to significantly higher cell densities than Ruegeria pomeroyi DSS-3, although there was no difference when cultured in media with reduced carbon. Genomic analysis showed that the bacterium utilized various pathways involved in biofilm formation, amino acid metabolism, and energy production via the oxidation of inorganic sulfur compounds. Transcriptomic analysis indicated that 28.4% of genes were regulated by carbon concentration, with increased carbon concentration inducing the expression of key enzymes in the EMP, ED, PP, and TCA cycles, genes responsible for the transformation of amino acids into TCA intermediates, as well as the sox genes for thiosulfate oxidation. Metabolomics showed that amino acid metabolism was enhanced and preferred in the presence of a high carbon concentration. Mutation of the sox genes decreased cell proton motive force when grown with amino acids and thiosulfate. In conclusion, we propose that copiotrophy in this Roseobacteraceae bacterium can be supported by amino acid metabolism and thiosulfate oxidation.

Structural and functional diversity of the microbiome during the Phaeocystis globosa winter bloom in the southern Yellow Sea of China

Phytoplankton blooms affect the microbial community seriously in marine ecosystems. Here, we used 16 S rRNA gene high-throughput sequencing and functional prediction to reveal the microbiome communities in different stages of the Phaeocystis globosa bloom in the southern Yellow Sea in December 2021. The total microbial abundance and diversity increased from the middle to the late stage of the bloom, but the dominant taxa remained the same, including Alphaproteobacteria, Bacteroidia, and Gammaproteobacteria. In terms of temporal changes, the abundance of Alphaproteobacteria decreased significantly over time (p < 0.05). The dominant families in both periods were Rhodobacteraceae and Flavobacteriaceae, but their abundance varied significantly over time (p < 0.05), for the proportion of Rhodobacteraceae decreased from 51.05% to 43.55%, while the Flavobacteriaceae increased from 16.60% to 20.91%. Other less abundant but important functional groups also varied significantly over time, with the percentage of Comamonadaceae decreased (p < 0.001), while Methylophagaceae and Microbacteriaceae increased dramatically (p < 0.01). The predicted functions of the microbial communities were characterized by chemoheterotrophy, oxidation of sulfur, sulfur compounds and sulfite, and reduction of nitrate, and significant differences were also observed between stages and fractions. Multiple environmental factors (temperature, phosphate, silicate, and colony density) showed significant effects on the microbial community, and phylogenetic-based mean nearest taxon distance (MNTD) analyses indicated that stochastic processes were more important in governing the spatiotemporal assembly of the microbiome during the bloom. Overall, the microbial responses to the P. globosa bloom suggested a substrate-controlled succession in the microbiome communities.

Oxidation of Sulfur Compounds by Sodium Hypochlorite over Molybdenum-Based Amphiphilic Catalysts

Oxidation of Sulfur Compounds by Sodium Hypochlorite over Molybdenum-Based Amphiphilic Catalysts

Microbiome of High-Rank Coal Reservoirs in the High-Production Areas of the Southern Qinshui Basin.

To study the distribution features of microorganisms in distinct hydrological areas of the southern Qinshui Basin, C-N-S microorganisms were studied using 16S RNA sequencing, metagenome sequencing and geochemical technologies, showing the high sensitivity of microorganisms to the hydrodynamic dynamics of coal. The hydrodynamic intensity of the #3 coal gradually decreased from the runoff areas to the stagnant areas. The stagnant zones have higher reservoir pressure, methane content, δ13CDIC and TDS and lower SO42-, Fe3+ and NO3- concentrations than the runoff areas. C-N-S-cycling microorganisms, including those engaged in methanogenesis, nitrate respiration, fermentation, nitrate reduction, dark oxidation of sulfur compounds, sulfate respiration, iron respiration, chlorate reduction, aromatic compound degradation, denitrification, ammonification and nitrogen fixation, were more abundant in the stagnant areas. The relative abundance of C-N-S functional genes, including genes related to C metabolism (e.g., mcr, mer, mtr, fwd and mtd), N metabolism (e.g., nifDKH, nirK, narGHI, nosZ, amoB, norC and napAB) and sulfur metabolism (e.g., dsrAB and PAPSS), increased in the stagnant zones, indicating that there was active microbiological C-N-S cycling in the stagnant areas. The degradation and fermentation of terrestrial plant organic carbon and coal seam organic matter could provide substrates for methanogens, while nitrogen fixation and nitrification can provide nitrogen for methanogens, which are all favorable factors for stronger methanogenesis in stagnant areas. The coal in the study area is currently in the secondary biogenic gas generation stage because of the rising of the strata, which recharges atmospheric precipitation. The random forest model shows that the abundance of C-N-S microorganisms and genes could be used to distinguish different hydrological zones in coal reservoirs. Since stagnant zones are usually high-gas-bearing zones and high-production areas of CBM exploration, these microbiological indicators can be used as effective parameters to identify high-production-potential zones. In addition, nitrate respiration and sulfate respiration microorganisms consumed NO3- and SO42-, causing a decrease in the content of these two ions in the stagnant areas.

Spatial comparison and temporal evolution of two marine iron-rich microbial mats from the Lucky Strike Hydrothermal Field, related to environmental variations

In hydrothermal environments, diffuse fluids emanations provide optimal conditions for the development of iron-rich microbial mats. Here, we present a unique spatial and temporal study of phylogenetic and chemical data from this type of mats and their associated hydrothermal fluids from two sites of the Lucky Strike Hydrothermal Field (EMSO-Azores deep-sea observatory), collected annually from 2016 to 2020. Our metabarcoding analyses reveal a completely different microbial community at each site, linked to the distinctive chemical composition of the diffuse fluids nourishing the mats. Capelinhos site is dominated by microorganisms with metabolisms related to iron, methane, and reduced sulphur compounds, coming from hydrothermal fluids, while North Tour Eiffel site presents higher abundances of microorganisms with metabolisms related to nitrogen, organic and oxidized sulphur compounds, coming from seawater. We present for the first time the yearly evolution of these mats over a five-year period. This analysis reveals similar variations of the microbial communities over time at both sites, indicating a regional Lucky Strike influence on the temporal scale. We also highlight more diversified microbial communities at both sites in 2016, pointing out the occurrence of a geological event that could have affected them during this specific year. Except for this year, our study shows that the communities of iron-rich microbial mats remain stable over time at both sites.

Vanadyl heterosubstituted 1,3-β-diketonate complexes: Synthesis, characterization and catalytic applications for the selective oxidation and detoxification of sulfur compounds

Six novel Vanadyl heterocyclic/aromatic substituted 1,3-β-diketonates complexes containing bidentate ligands have been synthetized and their structures full characterized by single crystals X-ray analyses (complexes 1–3), EPR spectroscopy either in a glassy state (100 K) or as powder, FT-IR and UV-Vis analyses. The coordination environment of the complexes (a distorted octahedron) is formed by two chelate dianions in the equatorial plane in a cis-planar configuration. The catalytic activity of these new oxidovanadium(IV) complexes has been studied in the selective oxidation of a series of sulfur-containing substrates toward their corresponding sulfides and/or sulfones, using tert-butyl hydroperoxide as primary oxidant. The effects of oxidant to substrate molar ratio, catalyst amount, solvent and temperature have been studied. The high activity and selectivity showed by the complexes, prompted us to apply, successfully, the catalyst 4 in the challenging decontamination of the mustard gas simulants CEES and CEPS, towards their corresponding sulfoxide derivatives, under mild conditions. A rationale analysis on the main observed results in terms of substrate conversion yields and sulfoxides (or sulfones) selectivities, has been addressed.

Catalytic activity of a new dioxidomolybdenum(vi) complex with a bipodal N2O-donor ligand in sulfur compound oxidation

A new dinuclear dioxidomolybdenum(vi) complex [(MoO2)2(BPA)2(μ-O)] was synthesized and evaluated as a catalyst in the reaction involving the oxidation of sulfur compounds.

A metagenomic insight into the microbiomes of geothermal springs in the Subantarctic Kerguelen Islands

The Kerguelen Islands, located in the southern part of the Indian Ocean, are very isolated geographically. The microbial diversity and communities present on the island, especially associated to geothermal springs, have never been analyzed with high-throughput sequencing methods. In this article, we performed the first metagenomics analysis of microorganisms present in Kerguelen hot springs. From four hot springs, we assembled metagenomes and recovered 42 metagenome-assembled genomes, mostly associated with new putative taxa based on phylogenomic analyses and overall genome relatedness indices. The 42 MAGs were studied in detail and showed putative affiliations to 13 new genomic species and 6 new genera of Bacteria or Archaea according to GTDB. Functional potential of MAGs suggests the presence of thermophiles and hyperthermophiles, as well as heterotrophs and primary producers possibly involved in the sulfur cycle, notably in the oxidation of sulfur compounds. This paper focused on only four of the dozens of hot springs in the Kerguelen Islands and should be considered as a preliminary study of the microorganisms inhabiting the hot springs of these isolated islands. These results show that more efforts should be made towards characterization of Kerguelen Islands ecosystems, as they represent a reservoir of unknown microbial lineages.

Disproportionation of Inorganic Sulfur Compounds by Mesophilic Chemolithoautotrophic Campylobacterota.

The disproportionation of inorganic sulfur compounds could be widespread in natural habitats, and microorganisms could produce energy to support primary productivity through this catabolism. However, the microorganisms that carry this process out and the catabolic pathways at work remain relatively unstudied. Here, we investigated the bacterial diversity involved in sulfur disproportionation in hydrothermal plumes from Carlsberg Ridge in the northwestern Indian Ocean by enrichment cultures. A bacterial community analysis revealed that bacteria of the genera Sulfurimonas and Sulfurovum, belonging to the phylum Campylobacterota and previously having been characterized as chemolithoautotrophic sulfur oxidizers, were the most dominant members in six enrichment cultures. Subsequent bacterial isolation and physiological studies confirmed that five Sulfurimonas and Sulfurovum isolates could disproportionate thiosulfate and elemental sulfur. The ability to disproportionate sulfur was also demonstrated in several strains of Sulfurimonas and Sulfurovum that were isolated from hydrothermal vents or other natural environments. Dialysis membrane experiments showed that S0 disproportionation did not require the direct contact of cells with bulk sulfur. A comparative genomic analysis showed that Campylobacterota strains did not contain some genes of the Dsr and rDSR pathways (aprAB, dsrAB, dsrC, dsrMKJOP, and qmoABC) that are involved in sulfur disproportionation in some other taxa, suggesting the existence of an unrevealed catabolic pathway for sulfur disproportionation. These findings provide evidence for the catabolic versatility of these Campylobacterota genera, which are widely distributed in chemosynthetic environments, and expand our knowledge of the microbial taxa involved in this reaction of the biogeochemical sulfur cycle in hydrothermal vent environments. IMPORTANCE The phylum Campylobacterota, notably represented by the genera Sulfurimonas and Sulfurovum, is ubiquitous and predominant in deep-sea hydrothermal systems. It is well-known to be the major chemolithoautotrophic sulfur-oxidizing group in these habitats. Herein, we show that the mesophilic predominant chemolithoautotrophs of the genera Sulfurimonas and Sulfurovum could grow via sulfur disproportionation to gain energy. This is the first report of the chemolithoautotrophic disproportionation of thiosulfate and elemental sulfur within the genera Sulfurimonas and Sulfurovum, and this comes in addition to their already known role in the chemolithoautotrophic oxidation of sulfur compounds. Sulfur disproportionation via chemolithoautotrophic Campylobacterota may represent a previously unrecognized primary production process in hydrothermal vent ecosystems.

Oxidative Desulfurization of Real High-Sulfur Diesel Using Dicarboxylic Acid/H2O2 System

From the perspective of pollution, economics, and product quality, it is very important to find an efficient way to minimize the sulfur content of petroleum products such as gasoline and diesel. In this work, an effective, inexpensive, and simple oxidative desulfurization system based on hydrogen peroxide activation by three dicarboxylic acids which have different carbon numbers (i.e., malonic acid, succinic acid, and glutaric acid) was utilized for the desulfurization of a real diesel sample with high organic sulfur-containing compounds. The desulfurization process was based on the oxidation of sulfur compounds in diesel fuel to the corresponding sulfones followed by acetonitrile extraction of the sulfones. To select the optimal experimental conditions, the effects of several parameters, including temperature, catalyst H2O2 dosages, and treatment time, were investigated. The results showed that the developed system was effective in desulfurizing real diesel fuel with high sulfur content. With an initial total sulfur content of about 8104 mg/L, the desulfurization rate from the diesel sample reached more than 90.9, 88.9, and 93%, using malonic acid, succinic acid, and glutaric acid, respectively. The optimum parameters such as reaction temperature, reaction time, H2O2 (50 w/w%), and carboxylic acid dosage for oxidative desulfurization were determined to be 95 °C, 6 h, 10 mL, and 0.6 g, respectively. The conversion of refractory sulfur compounds into extractable sulfone forms was verified using gas chromatography. Moreover, the kinetic study confirmed that the designed reaction system follows the pseudo-first-order kinetic model.