Deep Desulfurization of High-Sulfur Petroleum Coke via Alkali Catalytic Roasting Combined with Ultrasonic Oxidation.

The sulfur in petroleum coke is harmful to carbon products, underscoring the importance of desulfurization for high-sulfur petroleum coke. This paper proposes a method combining alkaline catalytic roasting with ultrasonic oxidation for the deep desulfurization of high-sulfur petroleum coke. The results show that the desulfurization rate reaches 88.99% and the sulfur content is reduced to 0.83 wt.% under a coke particle size of 96-75 µm, sodium-hydroxide-to-petroleum-coke ratio of 50%, roasting temperature of 700 °C, and holding time of 2 h. The alkali-calcined petroleum coke is ultrasonically oxidized and desulfurized in peracetic acid. The results show that, under a hydrogen peroxide content of 10%, hydrogen-peroxide-(liquid)-to-petroleum-coke (solid) ratio of 20 mL/g, acetic acid content of 5 mL, ultrasonic power of 300 W, reaction temperature of 60 °C, and reaction duration of 4 h, the sulfur content is reduced to 0.15 wt.% and the total desulfurization reaches 98.01%. Through a series of characterizations, the proposed desulfurization mechanism is verified. Alkali roasting effectively removes a significant portion of sulfur in petroleum coke. However, the elimination of certain sulfur compounds, such as the more complex thiophene, presents challenges. The thiophene content is subsequently removed via ultrasonic oxidation.

Investigating organic sulfur in estuarine and offshore environments: A combined field and cultivation approach.

Estuarine-offshore sediments accumulate substantial particulate organic matter, containing organic sulfur as a key component. However, the distribution and sources of organic sulfur in such environments remain poorly understood. This study investigated organic sulfur in the Yangtze River Estuary and adjacent East China Sea. Dissolved organic sulfur varied from 0.65 to 1.99 µmol/L (molar S:C 0.006-0.018), while particulate organic sulfur ranged from 0.42 to 2.69 µmol/L (molar S:C 0.007-0.082). Sedimentary organic sulfur exhibited a similar molar S:C ratio (0.014-0.071) to particulate organic sulfur in bottom water, implying that particulate matter deposition is a potential source. Furthermore, sediments exposed to frequent hypoxia harbored significantly higher organic sulfur and S:C values compared to non-hypoxic areas. Laboratory incubation experiments revealed the underlying mechanism: sustained activity of sulfate-reducing bacteria in hypoxic sediments led to a substantial increase in sedimentary organic sulfur (from 15 to 53 µmol/g) within 600 days. This microbially driven sulfurization rendered over 90 % of the organic sulfur resistant to acid hydrolysis. Therefore, this study demonstrates that, alongside particle deposition, microbial sulfurization significantly contributes to organic sulfur enrichment and likely promotes organic matter preservation in estuarine-offshore sediments, particularly under hypoxic conditions. This finding advances our understanding of organic sulfur sources in these vital ecosystems.

Electrophilic Compounds in the Human Diet and Their Role in the Induction of the Transcription Factor NRF2.

The phrase "Let food be thy medicine…" means that food can be a form of medicine and medicine can be a form of food; in other words, that the diet we eat can have a significant impact on our health and well-being. Today, this phrase is gaining prominence as more and more scientific evidence suggests that one's diet can help prevent and treat disease. A diet rich in fruits, vegetables, whole grains, and lean protein can help reduce the risk of heart disease, cancer, diabetes, and other health problems and, on the other hand, a diet rich in processed foods, added sugars, and saturated fats can increase the risk of the same diseases. Electrophilic compounds in the diet can have a significant impact on our health, and they are molecules that covalently modify cysteine residues present in the thiol-rich Keap1 protein. These compounds bind to Keap1 and activate NRF2, which promotes its translocation to the nucleus and its binding to DNA in the ARE region, triggering the antioxidant response and protecting against oxidative stress. These compounds include polyphenols and flavonoids that are nucleophilic but are converted to electrophilic quinones by metabolic enzymes such as polyphenol oxidases (PPOs) and sulfur compounds present in foods such as the Brassica genus (broccoli, cauliflower, cabbage, Brussel sprouts, etc.) and garlic. This review summarizes our current knowledge on this subject.

Biodesulfurization of organosulfur compounds by a trehalose biosurfactant producing Gordonia sp. isolated from crude oil contaminated soil.

Certain factors hinder the commercialization of biodesulfurization process, including low substrate-specificity of the currently reported desulfurizing bacteria and restricted mass transfer of organic-sulfur compounds in biphasic systems. These obstacles must be addressed to clean organic-sulfur rich petro-fuels that pose serious environmental and health challenges. In current study, a dibenzothiophene desulfurizing strain, Gordonia rubripertincta W3S5 (source: oil contaminated soil) was systematically evaluated for its potential to remove sulfur from individual compounds and mixture of organic-sulfur compounds. Metabolic and genetic analyses confirmed that strain W3S5 desulfurized dibenzothiophene to 2-hydroxybiphenyl, suggesting that it follows the sulfur specific 4 S pathway. Furthermore, this strain demonstrated the ability to produce trehalose biosurfactants (with an EI24 of 53%) in the presence of dibenzothiophene, as confirmed by TLC and FTIR analyses. Various genome annotation tools, such as ClassicRAST, BlastKOALA, BV-BRC, and NCBI-PGAP, predicted the presence of otsA, otsB, treY, treZ, treP, and Trehalose-monomycolate lipid synthesis genes in the genomic pool of strain W3S5, confirming the existence of the OtsAB, TreYZ, and TreP pathways. Overall, these results underscore the potential of strain W3S5 as a valuable candidate for enhancing desulfurization efficiency and addressing the mass transfer challenges essential for achieving a scaled-up scenario.

Extracellular organic disulfide reduction by Shewanella oneidensis MR-1.

Microbial reduction of organic disulfides affects the macromolecular structure and chemical reactivity of natural organic matter. Currently, the enzymatic pathways that mediate disulfide bond reduction in soil and sedimentary organic matter are poorly understood. In this study, we examined the extracellular reduction of 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) by Shewanella oneidensis strain MR-1. A transposon mutagenesis screen performed with S. oneidensis resulted in the isolation of a mutant that lost ~90% of its DTNB reduction activity. Genome sequencing of the mutant strain revealed that the transposon was inserted into the dsbD gene, which encodes for an oxidoreductase involved in cytochrome c maturation. Complementation of the mutant strain with the wild-type dsbD partially restored DTNB reduction activity. Because DsbD catalyzes a critical step in the assembly of multi-heme c-type cytochromes, we further investigated the role of extracellular electron transfer cytochromes in organic disulfide reduction. The results indicated that mutants lacking proteins in the Mtr system were severely impaired in their ability to reduce DTNB. These findings provide new insights into extracellular organic disulfide reduction and the enzymatic pathways of organic sulfur redox cycling.IMPORTANCEOrganic sulfur compounds in soils and sediments are held together by disulfide bonds. This study investigates how Shewanella oneidensis breaks apart extracellular organic sulfur compounds. The results show that an enzyme involved in the assembly of c-type cytochromes as well as proteins in the Mtr respiratory pathway is needed for S. oneidensis to transfer electrons from the cell surface to extracellular organic disulfides. These findings have important implications for understanding how organic sulfur decomposes in terrestrial ecosystems.

Mechanism Study of Organic Sulfur Hydrogenation over Pt- and Pd-Loaded Alumina-Based Catalysts.

The hydrogenation of organic sulfur (CS2) present in industrial off-gases to produce sulfur-free hydrocarbons and H2S can be achieved by using noble-metal catalysts. However, there has been a lack of comprehensive investigation into the underlying reaction mechanisms associated with this process. In this study, we have conducted an in-depth examination of the activity and selectivity of Pt- and Pd-loaded alumina-based catalysts, revealing significant disparities between them. Notably, Pd/Al2O3 catalysts exhibit an enhanced performance at low temperatures. Furthermore, we have observed that CS2 displays a higher propensity for conversion to methane when employing Pt/Al2O3 catalysts, while Pd/Al2O3 catalysts demonstrate a greater tendency for coke deposition. By combining experimental observations with theoretical calculations, we revealed that the capability of H2 spillover along with the adsorption capacity of CS2, play pivotal roles in determining the observed differences. Moreover, the key intermediate species involved in the methanation and coke pathways were identified. The intermediate CH2S* is found to be crucial in the methanation pathway, while the intermediate CSH* is identified as significant in the coke pathway.

Bacteria are driving the ocean's organosulfur cycle.

Bacteria are key players in the marine sulfur cycle, from the sunlit ocean surface to the dark abyssal depths. Here, we provide a brief overview of the interlinked metabolic processes of organosulfur compounds, an elusive sulfur cycling process that exists in the dark ocean, and the current challenges that limit our understanding of this key nutrient cycle.

Roasting and Cacao Origin Affect the Formation of Volatile Organic Sulfur Compounds in 100% Chocolate.

Chocolate is a highly appreciated food that develops its characteristic flavors in large part during the roasting of cacao beans. Many functional classes have been noted for their importance to chocolate flavor, including volatile organic sulfur compounds (VSCs). Despite this, the effect of roasting on the concentration of VSCs has never been thoroughly assessed. Here, we studied the effects of roasting temperature, time, and cacao origin on the formation of VSCs. Twenty-seven 100% chocolate samples made from cacao from three different origins and roasted according to an I-optimal experimental design were analyzed by comprehensive gas chromatography with sulfur-selective detection (GCxGC-SCD). For two compounds, dimethyl disulfide and dimethyl trisulfide, the effects of roasting time, roasting temperature, and cacao origin were modelled using response surface methodology and semi-quantified relative concentration. Overall, roasting increased the number of sulfur-containing volatiles present in chocolate, with a total of 28 detected, far more than previously thought. Increased roasting time and especially roasting temperature were found to significantly increase the concentration of VSCs (p < 0.05), while cacao origin effects were only seen for dimethyl disulfide (p < 0.05). The identity of most VSCs remains tentative, and more research is needed to unravel the impact of these volatiles on flavor perception in chocolate.

Oxygen vacancy-engineered titanium-based perovskite for boosting H2O activation and lower-temperature hydrolysis of organic sulfur.

Modulation of water activation is crucial to water-involved chemical reactions in heterogeneous catalysis. Organic sulfur (COS and CS2) hydrolysis is such a typical reaction involving water (H2O) molecule as a reactant. However, limited by the strong O-H bond in H2O, satisfactory CS2 hydrolysis performance is attained at high temperature above 310 °C, which is at the sacrifice of the Claus conversion, strongly hindering sulfur recovery efficiency improvement and pollution emissions control of the Claus process. Herein, we report a facile oxygen vacancy (VO) engineering on titanium-based perovskite to motivate H2O activation for enhanced COS and CS2 hydrolysis at lower temperature. Increased amount of VO contributed to improved degree of H2O dissociation to generate more active -OH, due to lower energy barrier for H2O dissociation over surface rich in VO, particularly VO clusters. Besides, low-coordinated Ti ions adjacent to VO were active sites for H2O activation. Consequently, complete conversion of COS and CS2 was achieved over SrTiO3 after H2 reduction treatment at 225 °C, a favorable temperature for the Claus conversion, at which both satisfying COS and CS2 hydrolysis performance and improved sulfur recovery efficiency can be obtained simultaneously. Additionally, the origin of enhanced hydrolysis activity from boosted H2O activation by VO was revealed via in-depth mechanism study. This provides more explicit direction for further design of efficacious catalysts for H2O-involved reactions.

Microbial Transformation of Dissolved Organic Sulfur during the Oxic Process in 47 Full-Scale Municipal Wastewater Treatment Plants.

Dissolved organic sulfur (DOS) is a significant part of effluent organic matter of wastewater treatment plants (WWTPs) and poses a potential ecological risk for receiving waters. However, the oxic process is a critical unit of biological wastewater treatment for microorganisms performing organic matter removal, wherein DOS transformation and its mechanism are poorly understood. This study investigated the transformation of DOS during the oxic process in 47 full-scale municipal WWTPs across China from molecular and microbial aspects. Surprisingly, evident differences in DOS variations (ΔDOS) separated sampled WWTPs into two groups: 28 WWTPs with decreased DOS concentrations in effluents (ΔDOS < 0) and 19 WWTPs with increased DOS (ΔDOS > 0). These two groups also presented differences in DOS molecular characteristics: higher nitrogen/carbon (N/C) ratios (0.030) and more peptide-like DOS (8.2%) occurred in WWTPs with ΔDOS > 0, implying that peptide-like DOS generated from microbes contributed to increased DOS in effluents. Specific microbe-DOS correlations (Spearman correlation, p < 0.05) indicated that increased effluent DOS might be explained by peptide-like DOS preferentially being produced during copiotrophic bacterial growth and accumulating due to less active cofactor metabolisms. Considering the potential environmental issues accompanying DOS discharge from WWTPs with ΔDOS > 0, our study highlights the importance of focusing on the transformation and control of DOS in the oxic process.

Biosynthesis, behavior and fate of volatile organic sulfide in Lentinus edodes (Berk.) upon hot-air drying treatment.

This study elucidated the biosynthesis and changing behaviors of organic sulfide in shiitake mushrooms upon hot-air drying treatment. The changes of aw, moisture migration, contours of taste and flavor, organic sulfide, and 4 key enzyme activities were monitored throughout three drying procedures (CT/ST1/ST2). Results showed that drying rate was related to the moisture migration. Key enzymes of γ-GTase, ASFase and CS lyase were heat-resistant proteases, while C-Dase exhibited low thermal stability with the activity decreased during treatment. A total of 17 organic sulfides were identified and PLS analyses suggested 6 cyclic polysulfides were formed by C-Dase desulfurization, while 5 thioethers generation were related to the thermal cleavage of direct precursors (straight-chain di/tris/tetrasulfonyl esters) and Maillard reaction. These results indicated that ST2 drying procedures had a positive effect on the formation of cyclic polysulfides at the end of drying pried and the achievement of premium flavor qualities.

Novel sulfur isotope analyses constrain sulfurized porewater fluxes as a minor component of marine dissolved organic matter.

Marine dissolved organic matter (DOM) is a major reservoir that links global carbon, nitrogen, and phosphorus. DOM is also important for marine sulfur biogeochemistry as the largest water column reservoir of organic sulfur. Dissolved organic sulfur (DOS) can originate from phytoplankton-derived biomolecules in the surface ocean or from abiotically "sulfurized" organic matter diffusing from sulfidic sediments. These sources differ in 34S/32S isotope ratios (δ34S values), with phytoplankton-produced DOS tracking marine sulfate (21‰) and sulfurized DOS mirroring sedimentary porewater sulfide (∼0 to -10‰). We measured the δ34S values of solid-phase extracted (SPE) DOM from marine water columns and porewater from sulfidic sediments. Marine DOMSPE δ34S values ranged from 14.9‰ to 19.9‰ and C:S ratios from 153 to 303, with lower δ34S values corresponding to higher C:S ratios. Marine DOMSPE samples showed consistent trends with depth: δ34S values decreased, C:S ratios increased, and δ13C values were constant. Porewater DOMSPE was 34S-depleted (∼-0.6‰) and sulfur-rich (C:S ∼37) compared with water column samples. We interpret these trends as reflecting at most 20% (and on average ∼8%) contribution of abiotic sulfurized sources to marine DOSSPE and conclude that sulfurized porewater is not a main component of oceanic DOS and DOM. We hypothesize that heterogeneity in δ34S values and C:S ratios reflects the combination of sulfurized porewater inputs and preferential microbial scavenging of sulfur relative to carbon without isotope fractionation. Our findings strengthen links between oceanic sulfur and carbon cycling, supporting a realization that organic sulfur, not just sulfate, is important to marine biogeochemistry.

Enhanced removal of sulfur-containing organic pollutants from actual wastewater by biofilm reactor: Insights of sulfur transformation and bacterial metabolic traits.

Sulfur-containing organic pollutants in wastewater could threaten human health due to their high malodor and toxicity, and their conversion processes are more complex than inorganic sulfur compounds. Membrane aerated biofilm reactor (MABR), as a novel and environmentally-friendly biofilm-based technology, is able to remove inorganic sulfur in synthetic wastewater. However, it is unknown how sulfur-containing organic pollutants in actual wastewater are transformed in MABR system. This work demonstrated the feasibility of MABR to eliminate sulfur-containing organic pollutants in actual wastewater, and the removal efficiency could be reached at approximately 100%. Meanwhile, over 70% of sulfur-containing organic contaminants were transformed to SO42- during the long-term operation. Further analysis indicated that the functional bacteria that participated in sulfur transformation and carbohydrates degradation (e.g., Chujaibacter, Microscillaceaesp., and Thiobacillus) were evidently enriched when treating actual wastewater. Moreover, the critical metabolic pathways (e.g., sulfur metabolism, glycolysis metabolism, and pyruvate metabolism), and the corresponding genetic expressions (e.g., nrrA, tauA, tauC, sorA, and SUOX) were evidently up-regulated during long-term operation, which was beneficial for the transformation of sulfur-containing organic pollutants in actual wastewater by MABR. This work would expand the application of MABR for treating the actual sulfur-containing organic wastewater and provide an in-depth understanding of the organic sulfur transformation in MABR.

Natural Asphalt Seeps Are Potential Sources for Recalcitrant Oceanic Dissolved Organic Sulfur and Dissolved Black Carbon.

Natural oil seepages contribute about one-half of the annual petroleum input to marine systems. Yet, environmental implications and the persistence of water-soluble hydrocarbons from these seeps are vastly unknown. We investigated the release of oil-derived dissolved organic matter (DOM) from natural deep sea asphalt seeps using laboratory incubation experiments. Fresh asphalt samples collected at the Chapopote asphalt volcano in the Southern Gulf of Mexico were incubated aerobically in artificial seawater over 4 weeks. The compositional changes in the water-soluble fraction of asphalt-derived DOM were determined with ultrahigh-resolution mass spectrometry (Fourier-transform ion cyclotron resonance mass spectrometry, FT-ICR-MS) and by excitation-emission matrix spectroscopy to characterize fluorescent DOM (FDOM) applying parallel factor (PARAFAC) analysis. Highly reduced aliphatic asphalt-derived DOM was readily biodegraded, while aromatic and sulfur-enriched DOM appeared to be less bioavailable and accumulated in the aqueous phase. A quantitative molecular tracer approach revealed the abundance of highly condensed aromatic molecules of thermogenic origin. Our results indicate that natural asphalt and potentially other petroleum seepages can be sources of recalcitrant dissolved organic sulfur and dissolved black carbon to the ocean.

An ultrasensitive SPI/PAI ion source based on a high-flux VUV lamp and its applications for the online mass spectrometric detection of sub-pptv sulfur ethers.

Single-photon ionization mass spectrometry (SPI-MS) is an attractive analytical technique for the online detection of volatile organic compounds; however, the low photon flux of the vacuum ultraviolet (VUV) lamp commonly used in the SPI ion source and the corresponding low detection sensitivity remain a constraint to its wide field applications. In this study, a new VUV lamp-based SPI ion source was developed. By increasing the discharging volume and optimizing the configuration of the lens and ionizer, the photon flux of the VUV lamp and the sensitivity of the ion source were significantly improved. The VUV lamp output was 2.8 × 1015 photons s-1, which was focused into the small ionization zone, and the ion intensity of gaseous benzene under SPI achieved 1.7 × 104 counts per second per pptv (cps pptv-1). This ion source can also function in photoinduced associative ionization (PAI) mode by introducing gaseous CH2Cl2 to initiate an associative ionization reaction. Because of the high efficiency of the ion source, the amount of doped CH2Cl2 needed for PAI was greatly reduced (∼2.5% of that used in previous experiments). PAI exhibited an outstanding protonation effect on monosulfur ethers (CnH2n+1S). The signal intensities of the protonated molecular ions (MH+) were 46-128 times higher than those of the molecular ions (M+) produced by SPI. Since monosulfur ethers generally have lower SPI cross-sections than polysulfur ethers (CnH2n+1S2 or CnH2n+1S3), the PAI and SPI modes were selected for the online measurement of a series of mono- and polysulfur ethers, respectively. The obtained detection sensitivity of the mono- and polysulfur ethers reached 476.5 ± 1.72-2835.1 ± 99.5 and 47.9 ± 0.4-105.1 ± 2.3 counts pptv-1, respectively, in 10 s of sampling time. The corresponding 3σ limits of detection (LODs) were 0.12-0.71 and 0.06-0.14 pptv, respectively. This study provides advances in the development of a high-flux VUV lamp and a highly efficient SPI/PAI ion source, as well as an ultrasensitive analytical method for detecting sulfur ethers.

Sulfur transformations during two-stage anaerobic digestion and intermediate thermal hydrolysis.

The formation of hydrogen sulfide (H2S) during anaerobic digestion (AD) imposes constraints on the valorisation of biogas. So far, inorganic sulfur compounds -mainly sulfate - have been considered as the main contributors to H2S formation, while the contribution of organic sulfur compounds is mostly neglected. This study investigates the fate of organic and inorganic sulfur compounds during two-stage anaerobic digestion with intermediate thermal hydrolysis for treatment of primary and secondary sludge in a WWTP treating domestic wastewater. The results of a seven-week monitoring campaign showed an overall decrease of organic sulfur compounds in both stages of anaerobic digestion. Further fractionation of organic sulfur revealed a high conversion of the particulate organic fraction during the first digestion stage and of the soluble organic fraction during the second digestion stage. The decrease of soluble organic sulfur during the second digestion stage was attributed to the solubilisation and hydrolysis of sulfur-containing organic compounds during thermal hydrolysis. In both digestion stages, more organic sulfur was taken up than particulate inorganic sulfur (metal sulfide) was produced, indicating the formation of other reduced sulfur forms (e.g. H2S). Further batch experiments confirmed the role of organic sulfur uptake in the formation of H2S during anaerobic digestion as sulfate reduction only partly explained the total sulfide formed (H2S in biogas and precipitated FeS). Overall, the conversion of organic sulfur was demonstrated to play a major role in H2S formation (and thus the biogas quality), especially in case of thermal hydrolysis pretreatment.

Significant fluctuation in the global sulfate reservoir and oceanic redox state during the Late Devonian event.

Ocean sulfate concentration might have fluctuated greatly throughout the Earth's history and may serve as a window into perturbations in the ocean-atmosphere system. Coupling high-resolution experimental results with an inverse modeling approach, we, here, show an unprecedented dynamic in the global sulfate reservoir during the Frasnian-Famennian (F-F) boundary event, as one of the "Big five" Phanerozoic biotic crises. Notably, our results indicate that, in a relatively short-time scale (∼200 thousand years), seawater sulfate concentration would have dropped from several mM before the Upper Kellwasser Horizon (UKH) to an average of 235 ± 172 µM at the end of the UKH (more than 100 times lower than the modern level) as the result of evaporite deposition and euxinia, and returned to around mM range after the event. Our findings indicate that the instability in the global sulfate reservoir and nutrient-poor oceans may have played a major role in driving the Phanerozoic biological crises.

Virus-associated organosulfur metabolism in human and environmental systems.

Viruses influence the fate of nutrients and human health by killing microorganisms and altering metabolic processes. Organosulfur metabolism and biologically derived hydrogen sulfide play dynamic roles in manifestation of diseases, infrastructure degradation, and essential biological processes. Although microbial organosulfur metabolism is well studied, the role of viruses in organosulfur metabolism is unknown. Here, we report the discovery of 39 gene families involved in organosulfur metabolism encoded by 3,749 viruses from diverse ecosystems, including human microbiomes. The viruses infect organisms from all three domains of life. Six gene families encode for enzymes that degrade organosulfur compounds into sulfide, whereas others manipulate organosulfur compounds and may influence sulfide production. We show that viral metabolic genes encode key enzymatic domains, are translated into protein, and are maintained after recombination, and sulfide provides a fitness advantage to viruses. Our results reveal viruses as drivers of organosulfur metabolism with important implications for human and environmental health.

Photosensitized formation of sulfate and volatile sulfur gases from dissolved organic sulfur: Roles of pH, dissolved oxygen, and salinity.

The photodegradation of dissolved organic sulfur (DOS) is a potential source of aqueous sulfate and its chemical precursors in surface water. However, the photochemical fate of DOS and factors that control its fate still remain unclear. Herein, we employed a DOS model featuring a photosensitizer (humic acids, HA) to investigate the photochemical degradation pathways of DOS in various natural water sources, from which we observed the substantial photosensitized formation of sulfate, methanesulfonic acid (MSA), carbonyl sulfide (COS), and carbon disulfide (CS2). However, the photochemical production of sulfate and MSA tends to be more efficient than COS and CS2. The formation of sulfur-containing photodegradation products was also strongly affected by the identity of the organic sulfur precursor, the oxygen concentration, and the pH, while the salinity did not significantly influence the production ratios. Our results revealed that the photosensitization of DOS contributed significantly to the overall production of sulfate and MSA production, especially in acidic and oxygen-enriched environments, which was attributed to the photochemical production of reactive intermediates, such as excited CDOM (3CDOM*) and reactive oxygen species (ROS). Considering the coexistence of DOS and photosensitizers in aquatic environments, photochemistry may play an essential role in the fate of aquatic DOS.

Removal of dimethyl sulfide by post-plasma catalysis over CeO2-MnOx catalysts and reaction mechanism analysis.

The combination of a multistage rod plasma reactor and post CeO2-MnOx catalysts is studied to treat dimethyl sulfide (DMS). The physicochemical properties of all catalysts and the effect of the catalytic performance of CeO2-MnOx catalysts on DMS removal efficiency are studied. Placing CeO2-MnOx catalysts after the non-thermal plasma system can improve the capability of DMS degradation. The results exhibit that CeO2-MnOx (1:1) catalyst presents a higher catalytic activity than that of CeO2, MnOx, CeO2-MnOx (1:0.5) and CeO2-MnOx (1:3). At the power of 21.7 W, the combination of dielectric barrier discharge and CeO2-MnOx (1:1) catalyst could improve the DMS removal efficiency and CO2 selectivity by 16.2% and 18.2%, respectively. This result maybe closely related with its specific surface area, redox properties and oxygen mobility. In addition, the degradation mechanism of DMS over CeO2-MnOx catalysts is proposed. Finally, the stability of the CeO2-MnOx (1:1) catalyst is investigated, and the reason for the decreased activity of the used catalyst is analyzed.