Sulfate Formation Research Articles

Thermodynamic Prediction of Scale Formation in Oil Fields During Water Injection: Application of SPsim Program Through Utilizing Advanced Visual Basic Excel Tool

This study focuses on the design and validation of a computer program named “SPsim”, developed using Visual Basic coding and advanced Excel tools to predict the formation of sulfate mineral deposits during water injection in oil fields. Water injection for secondary oil recovery is an effective economic strategy, but it can be negatively impacted by the formation of sulfate minerals such as calcium sulfate, gypsum, barium sulfate, and strontium sulfate. The results of this study demonstrate that SPsim can accurately predict the formation of these mineral deposits based on the composition of the formation water and injection water under various temperature and pressure conditions. Specifically, the formation of barium sulfate and calcium sulfate is observed under certain conditions, which is a significant concern in oil fields. The study also highlights that calcium sulfate, barium sulfate, and strontium sulfate are among the most challenging mineral deposits in the studied fields, while the formation of gypsum deposits is less significant. The program was compared with results from other software tools, such as ScaleChem 3.2 and StimCad 2, as well as field observations. The findings indicate that SPsim provides a reliable and effective tool for predicting and managing sulfate scaling in water injection operations, making it a valuable resource for both industrial and academic applications.

Decadal changes in summer aerosol composition and secondary aerosol formation mechanisms in Beijing

Abstract Aerosol chemistry in China has undergone significant transformation due to stringent emission control measures, leading to great shifts in aerosol composition and formation mechanisms. This study investigates the summer chemical evolution of aerosol species in Beijing over the past decade based on two summertime measurements using aerosol chemical speciation monitors. The results reveal a substantial decrease in fine particulate matter concentrations by 72.7% in summer over the past decade, particularly primary species that dropped by 86.3-95.1%. However, this improvement in particulate matter was accompanied by a worsening of ozone pollution between 2011 and 2022. In contrast, secondary components such as sulfate and secondary organic aerosol (SOA) exhibited significant increases in their contributions, rising from 18.2-25.5% to 21.4-41%. The varying responses of aerosol species to emission reductions are closely tie to changes in emission sources, aerosol chemistry, and meteorology. By decoupling the influence of meteorology through machine learning, our analysis highlights the crucial role of emission reductions in improving air quality, though with different impacts on aerosol chemistry. The dominant formation mechanisms of secondary components varied between the two summers, likely influenced by shifts in aerosol liquid water content and atmospheric oxidation capacity due to NOx reductions. Compared to the summer of 2011, the formation of sulfate and SOA in summer 2022 was primarily driven by photochemical processes related to ozone, with less impacts from aqueous-phase formation, while nitrate was predominantly formed via N2O5 heterogeneous hydrolysis. Considering the complex nature of secondary aerosol formation, future summer pollution control strategies should prioritize stricter collaborative regulation of precursors for both secondary aerosol and ozone.

Composition, Seasonal Dynamics and Metabolic Potential of the Rhizosphere Microbiome Associated with Wild White Poplar

The white poplar (Populus alba) is a dioecious woody plant with significant potential for the phytoremediation of soils. To realize this potential, it is necessary to utilize growth-promoting microorganisms. One potential source of such beneficial microorganisms is the rhizosphere community of wild-growing trees. However, the structure, dynamics, and metabolism of the rhizosphere community of wild-growing white poplar remain poorly understood. To ascertain seasonal dynamics, species diversity, and metabolic potential, we sequenced 16S rRNA genes in metagenomes derived from 165 soil samples collected in spring and autumn from the root surfaces of 102 trees situated in disparate geographical locations. The three most prevalent phyla across all samples are Proteobacteria, Actinobacteriota, and Acidobacteriota. At the order level, the most prevalent orders are Sphingomonadales and Rhizobiales. Accordingly, the families Sphingomonadaceae and Rhizobiaceae were identified as dominant. The rhizospheric microbiome exhibited substantial inter-seasonal variation. Six families, including Caulobacteraceae, Xanthomonadaceae, Chitinophagaceae, Chthoniobacteraceae, Sphingomonadaceae, and Rhizobiaceae, exhibited alterations (spring-to-autumn) across all geographical locations under study. Members of the Rhizobiaceae family, which includes nitrogen-fixing bacteria, can provide poplar with plant-available forms of nitrogen such as nitrate and ammonium. The rhizosphere microbiome may facilitate the conversion of inorganic sulfur into sulfur-containing amino acids, cysteine and methionine, that are bioavailable to plants. Furthermore, the rhizosphere microbiome is capable of synthesizing amino acids, organic acids (including Krebs cycle acids), and some lipids and sugars. Consequently, the rhizosphere community can stimulate poplar growth by providing it with readily available forms of nitrogen and sulfur, as well as building blocks for the synthesis of proteins, nucleic acids, and other macromolecules. Many of these pathways, including nitrogen fixation, were subjected to seasonal changes.

Improving SO2 Tolerance and Low-Temperature Denitrification Performance in NH3-SCR Catalysis: A Comprehensive Study on Nb and Mn Modified CeO2 Catalysts

In pursuit of improving the performance of MnCe-based catalysts in NH3-assisted selective catalytic reduction (NH3-SCR) of NOx technology, particularly their SO2 resistance and low-temperature activity, a series of NbMnCeOx catalysts were synthesized. Results reveal that the Nb0.1Mn2Ce5Ox catalyst provides the most excellent SO2 resistance and SCR catalytic activity. Incorporating Nb into the MnCeOx structure enriches the formation of additional chemisorbed oxygen species and surface acidity, promoting NO2 production while effectively preventing the over-oxidation of NH3 to produce N2O. The incorporation of Nb and Mn into CeO2 improves the content of Brønsted- and Lewis-acid sites, facilitating the NH3 capture and NH4+ generation, thus enabling the NH3-SCR process via both Eley-Rideal (E-R, Mechanism S1) and Langmuir-Hinshelwood (L-H, Mechanism S2) mechanisms, with the latter dominating at low temperatures. Nb doping considerably reduces the sulfate formation and the initial SO2 adsorption on the NbMnCeOx surface, while decreasing the average oxidation state of Mn and shielding it from electronic attack from S4+ in SO2. This study highlights the synergistic effect of Nb and Mn in bolstering acidic sites in CeO2-based catalysts and proposes the reaction mechanisms for improving the low-temperature and sulfur-resistant NH3-SCR performance.

Three-dimensional Zn foam coated with zeolitic imidazolate frameworks as stable zinc-ion battery anode

Zinc-ion batteries (ZIBs) offer several advantages including low cost, safety, and high volumetric capacity. However, the potential of ZIBs is hindered by dendrite Zn growth, by-products, and hydrogen evolution resulting in poor lifespan. Herein, this study adopts three-dimensional Zn foams coated with zeolitic imidazolate framework (ZIF) as an anode for ZIBs for the first time. NaCl is selected as a spacer and mixed with Zn powder to vary the pore and strut size of Zn foams. The optimal condition for ZIF coating is investigated taking into account corrosion and electrical resistance as well as hydrogen evolution. The ZIF layer leads to the homogeneous Zn deposition and suppresses the hydrogen evolution and the by-product formation of zinc hydroxide sulfate. A Zn foam with a spacer size of >300 μm, which shows the most stable behavior during stripping/plating tests in a beaker cell, is also employed in symmetric coin-cell tests. Its excellent lifespan characteristic is demonstrated at 1 and 3 mA/cm2 for 1-h intervals over a duration of 300 h. Furthermore, ZIF-coated Zn foam and MnO2-filled Ti foam are assembled in full cells to evaluate the ZIB performance. The full cells show a capacity retention of 75.7 % over 100 cycles, demonstrating the potential of ZIF-coated Zn foam as a ZIB anode. This work provides a solution to practical anodes for ZIBs by maximizing the inherent structural advantages of Zn foam with the adequate coating of ZIF.

The enhancement mechanisms of chondroitin sulfate on α-amylase activity: Exploring the interaction using in vitro and in silico studies

Glycosaminoglycans (GAG) are bioactive polysaccharide rich in -SO3- and -COO- groups, also known as acidic mucopolysaccharides. In this study, the feasibility of three structurally distinct forms of chondroitin sulfate (CS-A, CS-C, and CS-D) from the GAG family was explored as a potential strategy to enhance industrial α-amylase activity. All three CSs were found to increase α-amylase activity to varying degrees, with CS-D showing the most significant increase, exceeding 78 %. Furthermore, fluorescence quenching experiments indicated that the interaction between CS and α-amylase is primarily driven by hydrophobic interactions. In silico, molecular docking revealed that the sulfate groups of all three CSs form hydrogen bonds with α-amylase, with CS-D exhibiting the lowest binding energy due to its two sulfate groups. Kinetic simulations further suggested that binding to CS increases the flexibility of key active site residues (Asp197, Glu233, and Asp300), modifies the secondary structure, and enlarges the substrate-binding pocket, thereby promoting α-amylase's hydrolytic activity. Thus, this work revealed CS as an α-amylase activator and further elucidated its interaction mechanism using in vitro and in silico studies, which may be beneficial to apply CS in pharmaceutical or food industry.

Sulfur Induces As Tolerance in Barley Plants

The use of sulfur (S) in polluted soils can reduce metal(loid) toxicity and enhance phytoremediation effectiveness. Here we studied the response of barley plants to As in soil amended with sulfate or elemental sulfur throughout the growing cycle. A greenhouse experiment was carried out using 4-L pots filled with clay-loam soil spiked with 60 mg kg−1 As (Na2HAsO4·7H2O). Two chemical forms of sulfur (elemental sulfur (S0) or sulfate (CaSO4·2H2O)) were applied at a dose of 1 and 3 Mg ha−1, respectively, and two previously seeded barley plants were transplanted in each pot, using eight pots per treatment. At the end of the growing cycle, the biomass, nutrients, and metal(loid) content, as well as several physiological and biochemical parameters of the plants were analyzed. Moreover, the effect of the treatments on soil characteristics was also evaluated, including soil pore water. The treatment with sulfur promoted the growth of barley plants through their vegetative cycle, enhancing photosynthesis, although biomass did not significantly increase. Both sources of S promoted the accumulation of As in the root, thereby limiting its translocation to the aerial part of the plant, sulfate being more effective (an increase of 300%) than elemental S (an increase of 82%). The addition of S decreased soil pH. Furthermore, both treatments, but particularly sulfate, increased soluble sulfate and stimulated soil biological properties. In conclusion, the application of sulfate to As-polluted soil can enhance As phytostabilization by barley plants while simultaneously improving the biological properties of the soil.

Sulfur-resistant catalytic NO oxidation over surface-disproportionated CaMnO3 perovskites

A highly active CaMnO3 perovskite catalyst (CMO-H) was fabricated for NO oxidation, a key reaction in the control of NOx emissions from mobile and stationary sources, by tuning the average oxidation state of Mn on the surface via acid-initiated Mn disproportionation. In-depth structure-performance investigations suggest that an increased abundance of surface Mn4+ on CMO-H is responsible for its high activity. Doping with a tiny amount of Pd promoted the formation of reactive oxygen species on the CMO-H surface, leading to a further increase of NO oxidation activity which was largely sustained even in the presence of CO and hydrocarbons. Strikingly, an increased SO2-resistance was achieved over the Pd-doped CMO-H, due to an alleviation of surface sulfate formation by Pd. Our study sheds new lights on the rational fabrication of active, poisoning-resistant and cost-effective oxide catalysts for NO oxidation, which is an important reaction in various environmental and industrial applications.

From Ions to Crystals: A Comprehensive View of the Non-Classical Nucleation of Calcium Sulfate.

The early stages of mineralization continue to be in the focus of intensive research due to their inherent importance for natural and engineered environments. While numerous observations have been reported for single steps in the pathways of various crystallizing phases in previous studies, the complexity of the underlying processes and their elusive character have left central questions unanswered in most cases. In the present work, we provide a detailed view on the nucleation of calcium sulfate mineralization-an abundant mineral with broad use in construction industry-in aqueous systems at ambient conditions. As experimental basis, a co-titration procedure with potentiometric, turbidimetric and conductometric detection was developed, allowing solution speciation and the formation of crystallization precursors to be monitored quantitatively as the level of nominal (super)saturation gradually increases. The nature and spatiotemporal evolution of these precursors was further elucidated by time-resolved small-angle X-ray scattering (SAXS) and analytical ultracentrifugation (AUC) experiments, complemented by cryogenic transmission electron microscopy (cryo-TEM) as a direct imaging technique. The results reveal how ions associate into nanometric primary species, which subsequently aggregate and develop anisotropic order by intrinsic structural reorganization. Our observations challenge the common understanding of fundamental notions such as the nucleation barrier or the meaning of supersaturation, with broad implications for mineralization phenomena in general and the formation of calcium sulfate in geochemical settings and industrial applications in particular.

Von Ionen zu Kristallen: Neue Einblicke die nicht‐klassische Keimbildung von Calciumsulfat

AbstractDie frühen Stadien der Mineralisierung stehen aufgrund ihrer inhärenten Bedeutung für Prozesse in natürlicher Umgebung sowie in technischen Anwendungen weiterhin im Fokus intensiver Forschung. Obwohl bereits viele wertvolle Beobachtungen für einzelne Schritte in den verschiedenen Phasen eines Kristallisationsvorgangs berichtet wurden, blieben wesentliche Fragen zumeist unbeantwortet aufgrund der Komplexität der zugrundeliegenden Mechanismen und des transienten Charakters der beteiligten Vor‐ und Zwischenstufen. In der vorliegenden Arbeit geben wir einen detaillierten Überblick zur Keimbildung von Calciumsulfat (einem Mineral mit großer Bedeutung für die Bauindustrie) in wässrigen Systemen bei Umgebungsbedingungen. Als experimentelle Grundlage wurde ein Titrationsverfahren mit gleichzeitiger potentiometrischer, turbidimetrischer und konduktometrischer Detektion entwickelt, um die Assoziation von Ionen in Lösung und die Bildung von Vorläuferstrukturen bei kontinuierlich ansteigender nomineller Übersättigung quantitativ verfolgen zu können. Die Eigenschaften dieser Präkursoren und ihre zeitliche Entwicklung vor und während der Nukleation wurden in situ mittels Kleinwinkel‐Röntgenstreuung (SAXS) und analytischer Ultrazentrifugation (AUC) aufgeklärt. Zusätzlich wurde Transmissionselektronenmikroskopie unter kryogenen Bedingungen (Kryo‐TEM) als bildgebendes Verfahren genutzt. Die Ergebnisse zeigen, wie sich Ionen zu nanometrischen Primärspezies verbinden, die anschließend aggregieren und durch intrinsische strukturelle Reorganisation eine anisotrope Ordnung entwickeln. Unsere Beobachtungen stellen das gängige Bild von grundlegenden Begriffen wie der Keimbildungsbarriere oder der Bedeutung der Übersättigung in Frage. Daraus ergeben sich weitreichende Auswirkungen auf unser Verständnis von Kristallisationsphänomenen im Allgemeinen und der Bildung von Calciumsulfat in geochemischen und angewandten Systemen im Besonderen.

Boosting miniaturization in clinical analysis: determination of bisphenols in human serum and urine by miniaturized stir bar sorptive dispersive microextraction.

In this work, a miniaturized and sustainable method for the determination of endocrine-disrupting bisphenols in human serum and urine employing the miniaturized stir bar sorptive dispersive microextraction (mSBSDME) approach has been developed. As bisphenols are conjugated in the human body to their glucorinated and sulfated forms, an enzymolysis employing a commercial mixture of β-glucuronidase and arylsulfatase was carried out prior to the microextraction procedure to determine their total content. A magnetic covalent organic framework (COF) was employed as thesorbent to carry out the extraction of the analytes from the biological matrixes, showing good extraction performance dueto its hydrophobic, π-π, and dipole-dipole interactions with the analytes. As instrumental detection, liquid chromatography-tandem mass spectrometry (LC-MS/MS) was employed to achieve good sensitivity and selectivity. The method was validated for both matrixes, showing good linearity at least up to 100 ng mL-1, limits of detection in the low ng mL-1 range, good precision values (relative standard deviations below 15%), and good accuracy (relative recoveries between 80 and 127%). In order to show the applicability of the developed method, five samples from female volunteers were analyzed with the final aim of offering a practical tool for monitoring the female population's exposure to these highly endocrine-disrupting compounds. This new procedure enhances the implementation of miniaturized sample preparation approaches in biological samples for clinical analysis, giving special relevance to the sustainability of the method.

Lattice sulfuration enhanced sodium storage performance of Na0.9Li0.1Zn0.05Ni0.25Mn0.6O2 cathode

Introducing lattice oxygen redox for charge compensation in layered metal oxides is an effective way to develop advanced cathodes for high energy density sodium-ion batteries (SIBs). However, the asymmetry of lattice oxygen oxidation and reduction incurs oxygen release and crystal structure rearrangement, leading to poor reversibility of the charge and discharge process. Herein, a Na2S-assisted sulfuration strategy is firstly proposed to incorporate active sulfur into the crystal lattice of Na0.9Li0.1Zn0.05Ni0.25Mn0.6O2 cathode. The sulfur anions within the interior lattice participate in the redox process and enhance the integral coordination stability by mitigating undesired excessive oxygen redox, while the exterior sulfur forms a polyanionic layer to protect the particle surface against electrolyte corrosion. The incorporation of an extra redox center efficiently facilitates the increase of the discharge capacity from 159.9 to 179.2 mAh g−1 within the voltage range of 1.5–4.5 V. Moreover, the larger ionic radius of sulfur enlarges the interplanar spacing, thus facilitating Na+ ions transfer, especially at high current density. As a result, the modified cathode exhibits significantly enhanced electrochemical performance, with a capacity retention of 87 % after 100 cycles at 0.2 C and an excellent rate capability of 98.0 mAh g−1 at 10 C. Moreover, the assembled Na ion full cell based on a commercial hard carbon anode achieves an impressive capacity of 160.4 mAh g−1 at 0.1 C and could cycled steadily for over 100 cycles. The modification of layer oxides via sulfuration strategy provides a promising pathway for the structural design of novel cathodes with superior cycle performance for high-energy-density SIBs applications.

Antimony Vaporization and Condensation in Simulated Flash Smelting Off-Gas Train Conditions

AbstractAntimony is one of the most deleterious impurity elements in copper smelting and has a strong tendency to vaporize in the smelting furnace resulting in an enrichment of antimony in smelter flue dusts. The vaporization and condensation behavior of antimony species was studied in dust-free conditions simulating the off-gas train of a Flash Smelting Furnace at temperatures below 1273 K (1000 °C). The influences of the oxygen partial pressure and the condensate formation temperature on the characteristics of the precipitated antimony species were determined. It was found that practically all the vaporized antimony species precipitated between 853 K and 546 K (580 °C and 273 °C) and that a higher oxygen partial pressure favored precipitation at higher temperatures. The formation of antimony sulfate, which thermodynamically is the most stable antimony species in the studied conditions at temperatures below approximately 723 K (450 °C), was found to be kinetically constrained and the vaporized antimony species precipitated as oxides or sulfides depending on the oxygen partial pressure and the precipitate formation temperature.

Formation of a “Coat” of Copper Sulfate Around the Copper Cathode Depending on the Voltage Between the Electrodes in an Aqueous Suspension

This article studies the process of formation of copper sulfate crystallohydrate (CuSO4×5H2O) in an aqueous suspension when voltage is applied to copper electrodes. The factors influencing the intensity of the formation of copper sulfate, including the applied voltage, the distance between the electrodes and the composition of the water, are considered. Copper electrodes measuring 10×2 cm was used in the experiments. The distance between the electrodes varied from 2 to 10 cm. The electrodes were supplied with a voltage in the range from 2 to 29 V. The results of experiments, an analysis of the influence of various parameters on the crystallization process, as well as a discussion of possible reaction mechanisms are presented.

Positive Feedback between Partitioning of Carbonyl Compounds and Particulate Sulfur Formation during Haze Episodes.

Carbonyl compounds are important precursors of aqueous aerosols in the atmosphere, while their gas-particle partitioning behaviors and roles in particulate sulfur formation are poorly understood. In this study, we investigate the partitioning of five carbonyl compounds (formaldehyde, acetaldehyde, acetone, glyoxal, and methylglyoxal) during haze episodes in Beijing, China. On haze days, the values of field-derived effective Henry's law coefficients (KHf) on aerosols for these carbonyl compounds are 106-108 M atm-1, which are significantly higher (102-104 times) than those in pure water. Sulfate is observed to have a pronounced "salting-in" effect on these carbonyl compounds, resulting in at least 1-order-of-magnitude increase in their particle-phase concentrations. Parameterization schemes for their partitioning in the ambient aerosols were provided and applied to the multiphase chemical box model (RACM2-CAPRAM). When incorporated into the field-derived parametrization, the model significantly increased hydroxymethanesulfonate (HMS) production by 50-fold compared to using the parameters obtained in pure water, increasing from 2.6 × 10-2 to 1.23 μg m-3 h-1. The formed HMS can facilitate sulfate formation in turn through further oxidation by OH radicals and enhance aerosol hygroscopicity. These findings indicate a positive feedback loop between the partitioning of carbonyl compounds and particulate sulfur formation during haze episodes, providing new insights for controlling particulate pollution and reducing SO2 levels in urban areas.

Effect of Different Zn Concentrations on Crop Growth and Root Nodulation in Yard-Long Bean (Vigna unguiculata L.)

An experiment was conducted to study the effect of Zinc (Zn) as a micronutrient on growth and nodulation in Vigna unguiculata L. The experiment was carried out as a pot experiment in the Crop Farm, Faculty of Agriculture, Palachcholai, Eastern University, Sri Lanka from August to November 2023. The experiment was laid out in Complete Randomized Design with six treatments and four replicates. The treatments are T1 (Control), T2 (50 mg ZnSO4/kg soil), T3 (100 mg ZnSO4/kg soil), T4 (150 mg ZnSO4/kg soil), T5 (200 mg ZnSO4/kg soil) & T6 (250 mg ZnSO4/kg soil). The experiment used source of Zinc in the form of Zinc Sulphate (ZnSO4,5H2O) which yard-long bean plants can grow. The experiment results showed that, T2 treatment, the soil treated with 50 mg ZnSO4/kg soil significantly increase the Plant height, Chlorophyll content, Leaf area, Fresh weight of shoot & root, Dry weight of shoot & root, Number of nodules, Effective nodule percentage, as well as Soil respiration compared to the other treatments. However, beyond the level of 200 mg ZnSO4/kg soil, reduces the growth & nodulation of Vigna unguiculata L. and this shows that the level 200 mg ZnSO4/kg soil and beyond that level were the toxic level to the Vigna unguiculata L. Accordingly, the treatment T2 (50 mg ZnSO4/kg soil) was at the micronutrient level of Zn concentration which involved in many key cellular functions and show the best positive effect on growth and nodulation in Vigna unguiculata L. The results clearly indicate that, Zn can be use as a micronutrient up to a trace level in inducing plant growth and nodulation. However, at higher levels of Zn may act as heavy metal and cause phyto-toxicity in plants.

A fingerprint of source-specific health risk of PM2.5-bound components over a coastal industrial city

The influence of specific local land-use activities (continuously redistributing elements across environments) and environmental conditions (altering the chemical composition of airborne particulate matter) on the intrinsic health risk of PM2.5 exposure is sparsely reported. To fill this gap, we employed a novel integrated approach to address the influence of short-term changes in source-specific PM2.5 composition on the exposure-response risk, while controlling for weather conditions. We combine receptor-based source apportionment with conditional logistic regression in a space-time-stratified case-crossover design. This approach is different from previous studies as it: i) controls the impact of spatiotemporal variations in air pollution and human mobility using multilocation-specific fixed and disjointed space-time strata ii) addresses the spatial heterogeneity of personal exposure separating its variable effect from other predictors by allowing different baseline hazards for each space-time stratum; iii) aligns case/control periods with strong/regular episodes of source-specific PM-multipollutant fingerprint contributions rather than health outcomes. This enabled comprehensive examination of the association between source-specific PM2.5-bound species and cardiorespiratory disease hospitalizations. The epidemiological findings were that primary anthropogenic emissions [industrial (ORs 2.5 – 4.8)] were associated with higher 1-day moving average PM-induced risks. Natural-related sources [fresh / aged sea salt aerosol, dust, soil resuspension] and secondary sulfate formation were consistently associated with higher health risks (ORs 1.0 – 1.54) after 1 to 5-days since exposure. The results emphasize the importance of source-specific air quality management in complex areas and our research provides an adaptable universal tool to support targeted place-based policy interventions to mitigate air pollution impacts on health.

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.

Application of Stable Isotopes in Identifying the Sources and Formation of Sulfate and Nitrate in PM2.5: A Review

Sulfate and nitrate are important components of atmospheric PM2.5, which is the main contributor of haze. Therefore, studying the sources and formation mechanisms of atmospheric sulfate and nitrate is very important for the prevention and control of haze formation. Stable isotopes of sulfate and nitrate, including isotopic compositions of sulfur, oxygen, and nitrogen, can be comprehensively used to study the sources and formation pathways of sulfate and nitrate in PM2.5, and to evaluate the contribution of each source and each formation pathway. This paper briefly reviews the determination methods for sulfur, oxygen and nitrogen isotopes in sulfate and nitrate, focuses on the application of the above isotopes in identifying the sources and formation pathways of sulfate and nitrate in atmospheric PM2.5, and puts forward research prospects.

High temperature environmental scanning electron microscopy characterization of transient phase formation during conversion of simulated nuclear waste feed to glass

In-situ High-Temperature Environmental Scanning Electron Microscopy (HT-ESEM) is used to characterize the transient phases formed during the melting of complex glass batch mixtures representing simulated nuclear waste feeds. The first phenomenon that occurs is the formation of oxyanionic salt melt, followed by the reaction of oxyanionic salts with refractory grains containing Si, Al, or Mg through surface reactions to form a molten alkali-alumino-boro-silicate phase. The onset temperatures of gas bubble formation and primary foaming are directly determined from the HT-ESEM measurements. The formation of sulfate lakes as well as the formation of high-temperature transient phases floating at the sample surface are also directly observed and identified. Convection currents are observed and their consequences on glass homogenization are discussed.