Sulfur Research Articles

Characterization of Tetrathionate Hydrolase from Acidothermophilic Sulfur-Oxidizing Archaeon Metallosphaera cuprina Ar-4

Tetrathionate hydrolase (TTH) is a key enzyme for the oxidation of reduced inorganic sulfur compounds (RISCs) with the S4I pathway, which is distributed in autotrophic or facultative autotrophic sulfur-oxidizing bacteria and archaea. In this study, the enzyme TTHMc from the acidothermophilic archaeon Metallosphaera cuprina Ar-4T, encoded by mcup_1281 and belonging to the pyrroloquinoline quinone (PQQ) family, has been shown to possess tetrathionate hydrolysis activity. The molecular mass of the single subunit of TTHMc was determined to be 57 kDa. TTHMc is proved to be located in the cytoplasm, periplasmic space, and membrane, and the activity of them accounted for 72.3%, 24.0%, and 3.7% of the total activity. Optimal activity was observed at temperatures above 95 °C and pH 6.0, and the kinetic constants Km and Vmax were 0.35 mmol/L and 86.3 μmol/L, respectively. The presence of 0.01 mol/L Mg2+ enhances the activity of TTHMc, while 0.01 mol/L Ca2+ inhibits its activity. The hydrolysis of tetrathionate (TT) by TTHMc results in the production of thiosulfate, pentathionate, and hexathionate. This study represents the first description of TTH in the genus Metallosphaera, providing new theoretical insights into the study of sulfur-oxidizing proteins in acidothermophilic archaea.

Extraoral halitosis in functional dyspepsia and its association with small intestinal bacterial overgrowth.

Small intestinal bacterial overgrowth (SIBO) and extraoral halitosis are often observed in functional dyspepsia (FD). We aimed to identify their associations for the first time. In this study, extraoral halitosis was diagnosed and assessed through the organoleptic score (OLS). Total symptom score (TSS) of FD, small intestinal bacterial overgrowth (SIBO), gastric Helicobacter pylori (H. pylori) infection, and three exhaled volatile sulfur compounds (VSCs) (hydrogen sulfide, methyl mercaptan, and dimethyl sulfide [DMS]), were evaluated. Finally, 63 non-halitosis patients and 45 halitosis patients with extraoral halitosis were identified. Compared to non-halitosis patients, halitosis patients exhibited significantly higher TSS (86 [56, 123] vs. 43 [34, 57], P < 0.001) and SIBO positivity rate (66.67% vs. 11.11%, P < 0.001), but similar H. pylori positivity rate. The adjusted odds ratios of TSS and SIBO were 1.06 and 5.02, respectively. The area under curve (AUC) of the combination of TSS and SIBO for predicting extraoral halitosis was 0.89. Positive correlations were observed between TSS and OLS (r = 0.64), and between TSS and exhaled DMS level (r = 0.86), respectively. The other two VSCs were undetectable or of little value. We conclude that: (1) Extraoral halitosis is closely associated with FD and SIBO; (2) DMS is its primary contributing VSC; (3) FD patients with SIBO as opposed to gastric H. pylori infection are more prone to extraoral halitosis; (4) Clinicians should be aware of SIBO in the management of extraoral halitosis in FD.

Seasonal recurrence and modular assembly of an Arctic pelagic marine microbiome

Deciphering how microbial communities are shaped by environmental variability is fundamental for understanding the structure and function of ocean ecosystems. While seasonal environmental gradients have been shown to structure the taxonomic dynamics of microbiomes over time, little is known about their impact on functional dynamics and the coupling between taxonomy and function. Here, we demonstrate annually recurrent, seasonal structuring of taxonomic and functional dynamics in a pelagic Arctic Ocean microbiome by combining autonomous samplers and in situ sensors with long-read metagenomics and SSU ribosomal metabarcoding. Specifically, we identified five temporal microbiome modules whose succession within each annual cycle represents a transition across different ecological states. For instance, Cand. Nitrosopumilus, Syndiniales, and the machinery to oxidise ammonia and reduce nitrite are signatures of early polar night, while late summer is characterised by Amylibacter and sulfur compound metabolism. Leveraging metatranscriptomes from Tara Oceans, we also demonstrate the consistency in functional dynamics across the wider Arctic Ocean during similar temporal periods. Furthermore, the structuring of genetic diversity within functions over time indicates that environmental selection pressure acts heterogeneously on microbiomes across seasons. By integrating taxonomic, functional and environmental information, our study provides fundamental insights into how microbiomes are structured under pronounced seasonal changes in understudied, yet rapidly changing polar marine ecosystems.

Biofiltration for odor mitigation in water resource recovery facilities.

Odor emissions, primarily from anthropogenic activities like waste treatment and industrial processes, pose significant challenges in urban areas, particularly near water resource recovery facilities. While these emissions are generally not toxic, they can adversely affect community wellbeing and investment, prompting stricter regulations in some regions. For example, New York State's hydrogen sulfide guidelines are more stringent than federal standards. Hydrogen sulfide, along with other reduced sulfur compounds, volatile organic compounds, and nitrogen compounds, are among the key odorants produced by water resource recovery facilities. Various methods have been explored to mitigate these odors, including chemical treatments, operational modifications, and air treatment strategies like biofiltration, activated carbon adsorption, and regenerative incineration. Among these, biofiltration stands out as an environmentally friendly option due to its high efficiency in removing hydrogen sulfide and other odorants without the need for chemicals. Biofiltration systems, including biofilters and biotrickling filters, use microorganisms immobilized in a bed of porous media to degrade odorous compounds. Biofilters, which operate with intermittent water supply, are highly effective at total odor removal. In contrast, biotrickling filters, which use continuous nutrient and water flow, are better suited for higher pollutant loads but struggle with compounds of low solubility. Key factors influencing biofilter performance include the empty bed residence time, media type, moisture content, and microbial diversity. This review explores recent advancements in biofilter technology, with a focus on the removal of hydrogen sulfide and organic sulfur compounds. It also highlights real-world applications in water resource recovery facilities and discusses critical design and operational parameters for improving odor control, such as media selection, residence time, pH regulation, and microbial management. Key studies underscore the importance of media composition and nutrient supply in optimizing biofilter performance, especially at higher pollutant concentrations. Understanding these factors will help inform future improvements in odor management for water resource recovery facilities.

Distributions of DMS and DMSP and the influences of planktonic community assemblages in the Bohai Sea and Yellow Sea.

Dimethyl sulfide (DMS) and dimethylsulfoniopropionate (DMSP) are important sulfur compounds influenced by community assemblages of plankton. The distributions of DMS, DMSP, DMSP lyase activity (DLA), DMSP-consuming bacteria (DCB), and community structures of phytoplankton and zooplankton were investigated during summer in the Bohai Sea and Yellow Sea. The variety ranges of DMS, dissolved DMSP (DMSPd), and particulate DMSP (DMSPp) concentrations in the surface seawater were 1.46-28.52, 5.26-30.21, and 0.91-112.43nmol/L, with averages of 6.64, 14.27, and 37.53nmol/L, respectively. The maximum DMS and DMSPp concentrations appeared at stations H26 and H25 situated northeast of the Yangtze estuary, respectively. These maximum values maybe due to the enriched nutrients brought by the Yangtze River Diluted Water. Significantly positive correlations were observed between the DMS/DMSPp concentrations/DLA and chlorophylla (Chl a) concentration. Additionally, the phytoplankton abundances were markedly positively correlated with DMS concentrations and DLA. DCB abundances showed a significant positive correlation with DMSPd concentrations. These findings indicated that phytoplankton and bacterial communities significantly influenced the DMS and DMSPd distributions. Furthermore, microzooplankton grazing was demonstrated promote the total DMSP (DMSPt) turnover. These results elucidate the planktonic community assemblage roles in regulating the distributions of DMSP and DMS, contributing valuable insights into the biogeochemical cycle of organic sulfur compounds.

Cold liquid stabulation: Impact on the phenolic, antioxidant, and aroma characteristics of wines from aroma-neutral white grape varieties.

Cold liquid stabulation aims to extract valuable compounds from grape lees before juice clarification. In this study, 7, 14, and 21days of lees contact were tested on aroma-neutral 'Arneis' and 'Cortese' grape juices vs control. Basic parameters, colour, polyphenols, antioxidant capacity, and volatile organic compounds were assessed throughout winemaking. Wine sensory analysis was performed. The produced wines did not differ in terms of colour and show limited differences in polyphenols, not influencing astringency and bitterness. Variety and treatment length influenced free and glycosylated volatile organic compounds. Free terpenes increased in the 21-day treated 'Arneis' wine (+67%). Lower free esters in 'Arneis' with 14 days of stabulation were found (-10%). On the contrary, higher values of individual esters were found in 14 and 21-day treated 'Cortese' wines, but these showed lower free C6 (-12%) and sulphur compounds (-23% and-24%, respectively), and higher overall wine quality with respect to non-stabulated wine.

A review on the role of nanocomposites for desulfurization of liquid transportation fuels.

Stringent sulfur removal regulations from transportation fuels from typical levels of 500ppm to ultra-low levels of 10ppm (BS-6 standard) present a critical challenge for the crude processing industry. This research thoroughly investigates emerging desulfurization technologies, with a focus on nanocomposite (NC) materials that exhibit exceptional sulfur removal efficiency. Advanced nanocomposite catalysts, such as (TBA)4PW11Fe@TiO2@PVA, have near-complete removal rates of 96-99% for complicated sulfur compounds like dibenzothiophene (DBT) and derivatives. The performance spectrum spans from basic materials with 20-38% removal to advanced nanocomposite systems with up to 99% desulfurization efficiency. By synthesizing current strategies involving transition metal-based, polyoxometalate, and hybrid nanocomposite materials, this study highlights transformative approaches to meeting increasingly stringent environmental regulations in fuel processing, with selective removal techniques targeting specific sulfur molecular structures.

Theoretical insights on the adsorption of sulfur compounds over a CuCl2-loaded Metal–Organic Framework

Theoretical insights on the adsorption of sulfur compounds over a CuCl2-loaded Metal–Organic Framework

Mechanistic insight into the decomposition of sulfone compounds in supercritical water.

Supercritical water gasification (SCWG) is famous for the clean utilization of organic wastes without SOx emission. Investigating the decomposition mechanism of sulfone compounds, the dominant organic sulfur compounds of organic wastes, in supercritical water (SCW) is conducive to the development of SCWG technology. Herein, the comparative decomposition mechanism of phenyl vinyl sulfone (PVS), diphenyl sulfone (DS), and benzo[b]thiophene 1,1-dioxide (BD) are explored via experiments and density functional theoretical (DFT) calculations. Experiments on the decomposition characteristics of sulfone compounds in pyrolysis and SCW are conducted using a quartz tube reactor system at temperatures ranging from 400°C to 700°C. It is indicated that SCW can inhibit the generation of SO2 during the decomposition of sulfone compounds. The multi-step decomposition pathways that sulfone compounds thermal decompose in pyrolysis and react with H2O, H2, and free radicals (H•/OH•) in SCW are proposed by DFT calculations. It is proved that the presence of H• and OH• in SCW changes the decomposition pathways of sulfone compounds to suppress the release of SO2. This work contributes to a deeper understanding of the sulfur transformation of organic sulfur compounds and provides a theoretical foundation for the clean utilization of organic wastes in SCWG.

Odour prevention strategies in wastewater treatment and composting plants: A review.

Odour emissions from wastewater treatment plants (WWTPs) and composting plants (CPs) have become a critical environmental and public health issue due to the release of complex mixtures of volatile organic compounds, volatile inorganic compounds, and volatile sulphur compounds. These emissions do not only affect ambient air quality but also contribute to nuisance complaints and potential health risks in the nearby communities. This paper provides a comprehensive review of current odour prevention strategies employed in WWTPs and CPs, focusing on both the underlying mechanisms of odour generation and the efficacy of state-of-the-art mitigation techniques. Malodours mitigation approaches including physical, chemical, and biological methods such as the addition of chemical agents, the use of microbial inoculants, the application of adsorbents and bulking agents and the modifications of operational parameters are explored and their performance critically evaluated. By integrating cost-effective odour control strategies into plant design and operational practices, WWTPs and composting facilities can achieve substantial reductions in odour emissions and compliance with stringent environmental regulations, while enhancing relationships with neighbouring communities. Finally, this review underscores the importance of a holistic and multi-disciplinary approach to odour management, combining scientific innovation with practical engineering solutions.

Metagenomic insights into nitrite accumulation in sulfur-based denitrification systems utilizing different electron donors: functional microbial communities and metabolic mechanisms

Sulfur-based autotrophic denitrification (SADN) offers new pathway for nitrite supply. However, sequential transformation of nitrogen and sulfur forms, and the functional microorganisms driving nitrite accumulation in SADN with different reduced inorganic sulfur compounds (RISCs), remain unclear. Desirable nitrite accumulation was achieved using elemental sulfur (S0-group), sulfide (S2--group) and thiosulfate (S2O32--group) as electron donors. Under equivalent electron supply conditions, S2O32--group exhibited a superior nitrate conversion rate (NCR) of 0.285 kg N/(m³·d) compared to S2--group (0.103 kg N/(m³·d)). Lower NCR in S2--group was attributed to sulfide strongly inhibiting energy metabolism process of TCA cycle, resulting in reduced reaction rates. Moreover, the NCR of S0-group (0.035 kg N/(m³·d)) was poor due to the chemical inertness of S0. Specific microbial communities were selectively enriched in phylum level, with Proteobacteria increasing to an astonished 96.27-98.49%. Comprehensive analyses of functional genus, genes, and metabolic pathways revealed significant variability in the active functional genus, with even the same genus showed significant metabolic differences in response to different RISCs. In S0-group, Thiomonas (10.0%) and Acidithiobacillus (5.1%) were the primary contributor to nitrite accumulation. Thiobacillus was the most abundant sulfur-oxidizing bacteria in S2--group (43.84%) and S2O32--group (18.92%). In S2--group, it contributed to nitrite accumulation, while in S2O32--group, it acted as a complete denitrifier (NO3--N→N2). Notably, heterotrophic denitrifying bacteria, Comamonas (12.52%), were crucial for nitrite accumulation in S2O32--group, predominating NarG while lacking NirK/S. Overall, this work advances our understanding of SADN systems with different RISCs, offering insights for optimizing nitrogen and sulfur removal.

Accessible halitosis diagnosis: validating the accuracy of novel AI-based compact VSC measuring instrument

Halitosis presents a significant global health concern, necessitating the development of precise and efficient testing methodologies owing to the high prevalence and the associated social and psychological effects. The measurement of volatile sulfur compounds (VSCs), recognized as primary contributors to halitosis, is particularly significant. While gas chromatography (GC-MS) offers accurate measurements, its bulky and expensive nature limits widespread accessibility. Hence, this study endeavors to devise a compact yet highly accurate AI-based halitosis measurement apparatus, termed 'Kunkun dental' and validate its efficacy. Specifically, we intend to compare the VSC concentrations obtained from halitosis patients' breath samples using Kunkun dental against those from conventional GC-MS to assess the criterion validity of the new testing method. The study cohort comprised 68 halitosis patients aged 20 years or older, attending the breath freshening outpatient clinic at Tokyo Medical and Dental University Hospital between October 2022 and March 2023, who consented to participate and underwent routine measurements. Participants completed an age and sex questionnaire, while VSC concentrations were determined using both GC-MS and Kunkun dental (H2S, CH3SH, (CH3)2S), enabling a comparative analysis of the results. Pearson product-moment correlation coefficients between GC-MS and Kunkun dental indicated significant correlations for all three gases: 0.719 for H2S, 0.821 for CH3SH, and 0.637 for (CH3)2S. Moreover, sensitivity and specificity in accordance with the predefined thresholds were confirmed, and their values ranged from 0.59 to 0.86 and 0.53-0.77, respectively. Furthermore, grouping Kunkun dental measurements into low-, medium-, and high-concentration groups revealed significantly higher GC-MS VSC concentrations in samples with elevated Kunkun dental readings. The amalgamation of AI technology and a semiconductor gas sensor holds great promise in creating a compact and precise halitosis analyzer. This study underscores the feasibility and effectiveness of Kunkun dental as a reliable tool for halitosis assessment, affirming its utility in clinical practice.

Predicting the detectability of sulphur-bearing molecules in the solid phase with simulated spectra of JWST instruments

To date, gas phase observations of sulphur in dense interstellar environments have only constrained the molecular carriers of ∼ 1 % of its predicted cosmic abundance. An additional ∼ 5 % is known to be locked up in molecular solids in dense clouds, leaving the main reservoir of depleted sulphur in the solid phase yet to be identified. Overall, OCS is the only S-bearing molecule unambiguously detected in interstellar ices thus far with infrared telescopes, although an absorption feature of SO_2 has been plausibly identified at 7.5 μm. The spectral resolution and sensitivity of the James Webb Space Telescope (JWST) could make a substantial difference in detecting part of this missing sulphur. The wavelength coverage of the JWST includes vibrational absorption features of the S-carriers H_2S, OCS, SO_2, CS_2, SO, CS, and S_8 are found. The aim of this study is to determine whether these molecules may be viable candidates for detection. We carried out new laboratory measurements of the IR absorption spectra of CS_2 and S_8 to update the IR band strength of the most intense CS_2 absorption feature at 6.8 μm, as well as to determine that of S_8 at 20.3 μm for the first time. These data, along with values previously reported in the literature for H_2S, OCS, and SO_2, allow us to evaluate which S-bearing species could be potentially detected with JWST in interstellar ices. Taking the literature abundances of the major ice species determined by previous IR observations towards starless cores, low-mass young stellar objects (LYSOs) and massive young stellar objects (MYSOs), we generated simulated IR spectra using the characteristics of the instruments on the JWST. Thus, we have been able to establish a case study for three stages of the star formation process. These spectra were simulated using a tool that produces synthetic ice spectra, with the aim of studying the feasibility of detecting S-bearing species with the JWST by artificially adding S-bearing molecules to the simulated spectra. We conclude that the detection of S-bearing molecules remains challenging due to a variety of parameters; principally, the overlap of absorption features with those of other species and the mixing of molecular species in the ice impacting the profile and central position of the targeted bands. Despite these obstacles, the detection of H_2S in dense clouds -- and potentially SO_2 in LYSOs and MYSOs -- should be possible in regions with favourable physical and chemical conditions, but not necessarily in the same region. In contrast, the large allotrope S_8 would remain undetected even in the unrealistic case that all the available sulphur atoms were involved in its formation. Although the sensitivity of JWST is insufficient to determine the sulphur budget in the solid state, the detection of (or setting of significant upper limits on the abundance of ) an additional icy sulphur compound (H_2S, SO_2) would enable us to validate a state-of-the-art approach in our knowledge of sulphur chemistry, offering a unique opportunity to make comparisons against future developments.

The effect of salivary flow rate on the risk of bad breath (halitosis) during the Ramadan fasting

Background: Ramadan fasting is a significant religious practice for Muslims, characterized by abstinence from food and drink from dawn to sunset. This fasting routine induces physiological changes, including reduced salivary flow and altered salivary composition, which may compromise oral health. These changes increase the risk of halitosis and other oral issues due to decreased protective functions of saliva and the proliferation of volatile sulfur compound (VSC)-producing bacteria. Objective: To review the relationship between reduced salivary flow during Ramadan fasting and the risk of halitosis, as well as to identify effective preventive measures to mitigate these effects. Method: A literature review was conducted using secondary data from databases such as PubMed, ScienceDirect, and Google Scholar. The inclusion criteria focused on studies published between 2017 and 2025 that explored salivary flow rate, halitosis, and the effects of Ramadan fasting. Results: The review highlighted a significant reduction in salivary flow, with rates decreasing up to 50% during fasting. This reduction leads to an increase in VSC levels, which are the primary contributors to halitosis. Additionally, fasting affects the composition of saliva, including lower levels of phosphate and calcium, further exacerbating oral health issues. Conclusion: Ramadan fasting significantly influences oral cavity health by reducing salivary flow and altering its composition, increasing the risk of halitosis and other dental issues. Halitosis is primarily caused by volatile sulfur compounds produced by gram-negative anaerobic bacteria thriving in reduced saliva conditions.

Optical characteristics and formation mechanism of haze events in Qingdao, a coastal city in China

During the field campaign conducted in Qingdao, Shandong Province, from December 2019 to January 2020, six significant haze episodes occurred. To investigate the optical characteristics and formation mechanisms of haze in this region, we utilized an optical particle counter to measure the size distribution of aerosol particles. The results showed that the average Angström exponent value during the campaign was 1.45, indicating that fine particulate matter dominated. Additionally, the aerosol scattering coefficient, absorption coefficient, and single scattering albedo were measured using a cavity-attenuated phase shift instrument. It was observed that both scattering and extinction coefficients significantly increased during the haze episodes, while SSA notably decreased at the onset of haze, which may be related to newly emitted aerosol particles. Air quality monitors detected a marked increase in sulfur compounds and nitrogen oxides during the haze episodes, with nitrogen oxides being higher than sulfur compounds, indicating that local pollution was primarily driven by vehicular emissions. Using the HYSPLIT4 model, we analyzed atmospheric transport trajectories and found that regional transport played a critical role in haze events. Analysis of micropulse lidar data revealed that the boundary layer height during the haze episodes was significantly lower than during non-haze periods. The lower boundary layer height restricted pollutant dispersion, exacerbating pollution levels. High relative humidity also contributed to the hygroscopic growth of aerosols, altering atmospheric thermal balance and playing a crucial role in the formation of haze events.

Type III porous ionic liquids via lipophilicity differences for enhanced oxidation catalysis

AbstractIn this study, an innovative strategy is proposed to design porous ionic liquids (PILs) using lipophilicity differences, defined as type III‐B PIL, which overcomes the traditional size‐effect limitations in PIL design. An SBA‐15 confined high‐entropy single‐atom catalyst (HESAC@SBA‐15) with an oleophobic internal surface was engineered as the porous framework and oleaginous 1‐butyl‐3‐methylimidazolium tetrafluoroborate as the organic guest for constructing a novel type PIL (PILS‐B). This type of PILS‐B combines the exceptional gas storage capacity of PILs with the high catalytic activity of HESAC@SBA‐15. Additionally, the mesoporous structure of SBA‐15 enhances mass transfer during reactions, thereby improving catalytic efficiency. Using the aerobic oxidation of aromatic sulfur compounds in fuel oils as a model reaction, PILS‐B achieved a desulfurization efficiency of &gt;99%. This strategy expands the variety of porous frameworks and organic guests for PIL design, showcasing the potential of PILs as effective and stable catalysts with broader applications in catalysis.

Effect of Four Different Initial Drying Temperatures on Biochemical Profile and Volatilome of Black Tea

Background: Black tea processing conditions significantly affect the final taste and flavor profiles, so researchers are now focusing on developing equipment and improving the appropriate processing conditions of major black tea varieties. Methods: Here, we tested the effect of four different initial drying temperatures, i.e., R65 (65 °C), R85 (85 °C), R105 (105 °C), and R125 (125 °C), on the sensory and biochemical profiles and volatilome of the black tea variety “Lishui wild” (LWV). Results: Our results indicate that both 85 and 105 °C are better than 65 and 125 °C for initial drying for 20 min. R105 had the highest sensory evaluation scores due to better shape, aroma, taste, leaf base, thearubigins, theanine, caffeine, and ratio of theaflavins + thearubigins to theaflavins. Both R85 and R105 had higher catechins than R65 and R125. The LWV volatilome consisted of esters (19.89%), terpenoids (18.95%), ketones (11.3%), heterocyclic compounds (9.99%), and alcohols (8.59%). In general, acids, aldehydes, amines, aromatics, ethers, hydrocarbons, phenols, sulfur compounds, and terpenoids accumulated in higher amounts in R85 and R105. The highly accumulated compounds in R105 were associated with green, fruity, sweet, woody, floral, hawthorn, mild, nutty, powdery, rose, and rosy flavors. The main pathways affected are secondary metabolites, sesquiterpenoid and triterpenoid biosynthesis, glycerolipid metabolism, zeatin biosynthesis, phenylpropanoid biosynthesis, ABC transport, glutathione metabolism, etc. Therefore, R105 can be used to achieve the optimal taste, flavor, and aroma of LWV. Conclusions: Overall, the presented data can be used by the tea industry for processing black tea with the most optimum volatile substances, catechins, theanine, amino acids, and other compounds.

Desulfurization of light and heavy gas oil from crudes of Kurdistan region-Iraq by oxidation and solvent extraction

This study analyzes four distinct crude oil varieties from the Kurdistan Region-Iraq: Taq-Taq (TQ), Sarqala (SA), Khurmala (Kh), and Tawke (TA). Fractionation produced five categories: naphtha, kerosene, light gas oil (LGO), heavy gas oil (HGO), and fuel oil. The research focused on distillation cuts of LGO (241–300°C) and HGO (301–360°C), which contained organic sulfur compounds, contributing to environmental pollution and health hazards during combustion. Oxidative desulfurization (ODS) using hydrogen peroxide and acetic acid at 75°C for 12 hours significantly reduced sulfur content. LGO sulfur content decreased from 0.72% to 0.11% wt in SA and from 2.02% to 0.50% wt in TA, achieving desulfurization efficiencies of 84.72% and 74.25%, respectively. In HGO, sulfur content dropped from 3.67% to 1.78% wt in Kh, with 51.49% efficiency. Gas oil recovery after oxidation ranged from 92.71% to 96.28%. Solvent extraction with acetonitrile, methanol, and acetic acid further enhanced desulfurization, with pre-oxidation extraction achieving 19.42% efficiency in LGO, increasing to 86% post-oxidation. Gas chromatography with a flame photometric detector (PFPD) assessed sulfur removal, highlighting the combined effects of oxidation and extraction on sulfur compound reduction. This approach demonstrated the efficiency of ODS in mitigating sulfur-related impacts.

Hierarchically Porous Titanosilicate Hollow Spheres Containing TS-1 Zeolite Precursors for Oxidative Desulfurization

The environmental and health impacts of sulfur compounds in fuel oil have prompted considerable research interest in oxidative desulfurization (ODS) technology. Tetrahedrally coordinated titanium has been demonstrated to exhibit excellent activity in the context of oxidative desulfurization processes. However, further improving the catalytic property of the tetrahedrally coordinated titanium remains a challenging endeavor. In the context of ODS processes conducted at near room temperatures, the improvement of conversion remains a subject of considerable challenge. In this study, hierarchically porous titanosilicate hollow spheres were synthesized by using TS-1 zeolite precursors as Ti and Si sources to obtain the catalyst with only tetrahedrally coordinated titanium. The synthesized materials were characterized through transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), ultraviolet–visible diffuse reflectance spectroscopy (UV-Vis), and nitrogen adsorption analysis. These techniques confirmed the formation of hollow spherical hierarchically porous structures with Ti species uniformly incorporated in tetrahedral coordination and the presence of five-member rings of TS-1 zeolite. As a result, the hierarchically porous titanosilicate hollow spheres demonstrated excellent catalytic performance in ODS, achieving complete dibenzothiophene (DBT) removal within 15 min and a high turnover frequency (TOF) of up to 123 h−¹ at 30 °C.

Identification of Volatile Compounds in Pennycress Protein Isolates Produced by Both Alkaline and Salt-Based Processes.

Volatile off-notes in ground pennycress seeds, ground defatted pennycress seed, and the final protein isolates (produced from the defatted seeds by alkaline or salt extraction) were identified and "quantified" relative to an internal standard. Volatiles contributing off-notes were identified based on mass spectra, retention indices, and aroma descriptors. The compounds that produced the strongest odors based on gas chromatography:olfactometry were identified as potential aroma impact compounds. In ground pennycress seeds, sinigrin degradation products (e.g., allyl isothiocyanate) and other sulfur-containing volatile compounds were most potent. The primary odorants found in pennycress defatted meals were similar to the seeds but uniquely contained additional aldehydes associated with lipid degradation. The volatile profile of the final alkaline-based isolate contained substantial quantities of aldehydes, isothiocyanates/thiocyanates, and other sulfur compounds. The volatile profile of the salt-extracted protein isolate contained fewer volatiles and was much milder in aroma than that of the alkaline-based protein isolate. The aroma of this latter protein isolate was dominated by aldehydes from lipid degradation as opposed to volatiles arising from sinigrin degradation (e.g., thiocyanates).