High SO2 Research Articles

Modulator-Directed Counterintuitive Catenation Control for Crafting Highly Porous and Robust Metal-Organic Frameworks with Record High SO2 Uptake Capacity.

Sulfur dioxide (SO2) is an important industrial feedstock that can be directly utilized or catalytically transformed to value-added chemicals such as sulfuric acid. The development of regenerable porous sorbents for the highly efficient storage and energy-minimal release of toxic SO2 operating under ambient conditions has attracted growing interest. Herein, we report the topology-guided construction of highly porous acs-type metal-organic frameworks (MOFs) through a counterintuitive modulator-directed catenation control approach. In contrast to the conventional modulator facilitated coordination competition that favors the thermodynamic catenated phase, we show that the elevation of modulator concentration can promote the formation of the noncatenated phase probably through a sublattice dissolution pathway. The assembly of a custom-designed trigonal prismatic triptycene-quinoxaline linker and trinuclear Fe3O cluster affords either the threefold catenated SJTU-219 or noncatenated SJTU-220 with desired acs net. Impressively, the synthetic approach is applicable to various metal ions, including Al3+, V3+, and even Ti4+. The noncatenated SJTU-220 exhibits an extraordinary SO2 sorption capacity of 29.6 mmol g-1 at 298 K and 1 bar, surpassing all reported solid sorbents. The uptake capacity can be further raised to 35.6 mmol g-1 via the replacement of Fe3+ with kinetically more inert Cr3+, resulting in a staggering ∼329-fold volume reduction compared with free ideal SO2 gas. Computational simulations suggest that unique Fe3+···S(SO2) interactions dominate the SO2 seeding process, facilitating the efficient packing of SO2 molecules in the large channels. Besides, the exceptionally low uptake at the low pressure region implies global weak framework-SO2 interactions, which offer great potential for practically implementing an "easy-on/easy-off" SO2 delivery system.

Facile preparation of zirconium(IV) immobilized carboxymethyl cellulose/multiwalled carbon nanotubes gels by radiation technique and its selective fluoride removal

Removal of excessive fluorine in the waterbody environment and the Zn hydrometallurgical system is an urgent problem. In this paper, zirconium oxychloride immobilized carboxymethyl cellulose/carboxymethyl multiwalled carbon nanotube (CMC+MWCCNT-ZrOCl2) gels are facilely prepared by radiation technique. The addition of MWCCNT endows the CMC-ZrOCl2 gel a typical nanotubes/fiber structure, also increase the gel fraction of the gel. The selective adsorption of fluoride from single or co-existed anions was investigated. The adsorption isotherms can be well fitted by both the Langmuir and Freundlich model. The calculated maximum adsorption capacity was 36.657 mg/g. The selectivity coefficients of CMC+MWCCNT-ZrOCl2 for fluoride versus NO3−, PO43−, and SO42− are 140.34, 10.953, and 72.572, respectively. Also, CMC+MWCCNT-ZrOCl2 can be used as a potential adsorbent for selective removing F− from high concentration SO42− solution. The adsorption mechanism was investigated by XPS analyses.

Redox ability dependent SO2 tolerance for low-temperature NH3-SCR of MnO2@MeOX (Me = Ti, Ce, Cu) catalysts

Elucidating the deposition behavior of sulfates on catalysts of low-temperature ammonia-assisted selective catalytic reduction (NH3-SCR) helps improve their SO2 tolerance and applicability. Therefore, this study aimed to explore the impact of the redox properties of low-temperature NH3-SCR catalysts on their catalytic activity and SO2 tolerance. Oxidizing Mn@Ce, neutral Mn@Ti, and reducing Mn@Cu catalysts were prepared, and their NH3-SCR activities and SO2 tolerances were evaluated. Subsequently, the characteristics of the catalyst poisoned by SO2 over time and the deposition behavior of sulfates on the catalyst were analyzed to determine the reaction pathway between SO2 and the NH3-SCR catalyst. The SO2 tolerance of the catalysts decreased in the following order: oxidizing Mn@Ce > neutral Mn@Ti > reducing Mn@Cu. Combined with the characteristic results, we found that the amount of shell-metal sulfate increased with SO2 poisoning time, indicating it was the dominant factor in catalyst deactivation. Specifically, the amount of shell-metal sulfate followed the order Mn@Cu-S12 (31.4 µmol) > Mn@Ti-S12 (24.9 µmol) > Mn@Ce-S12 (9.5 µmol). Additionally, the increasing SO42− ratio from Mn@Me-S4 to Mn@Me-S12 followed the order Mn@Cu (6.7 %) > Mn@Ti (4.4 %) > Mn@Ce (1.7 %), implying that the reduction of Mn@Cu favors chemical SO2 poisoning pathway and facilitates the deposition of copper sulfate. In contrast, Mn@Ce with its strong oxidation properties, is beneficial for inhibiting the chemical poisoning pathway of SO2 and alleviating the deposition of cerium sulfate. Consequently, this study demonstrates that the redox ability of catalyst regulates the SO2 poisoning pathways, aiding the development of low-temperature NH3-SCR catalysts with high SO2 tolerance.

Controls on regional sulphate distribution in shallow groundwater in the western Canadian Interior Plains

Sulphate (SO4), predominantly derived from sulphur (S)-bearing glacial sediments distributed widely across the Canadian Interior Plains, contributes to high groundwater salinity and can be detrimental to riparian and dry-land ecosystems, agricultural production, and water use. While previous researchers investigated SO4 distribution and dynamics in shallow groundwater at local scales (<1500 km2), we examine SO4 occurrence in groundwater at larger scales, and to depths of ~150 m, considering variations in geology, glacial history, climate, and geochemical and hydrogeological settings in the Canadian province of Alberta. Sulphate concentrations in groundwater vary considerably, with 15 % of 139,130 samples above the 500 mg/L Canadian drinking water aesthetic objective. Analysis of δ34SSO4 and δ18OSO4 from 179 wells throughout Alberta shows SO4 is dominantly derived from oxidation of S-bearing material. At this large scale, marine shale bedrock subcrops, glacial ice flow directions, and climate control SO4 distribution. Groundwater contains less SO4 (<200 mg/L) in western Alberta compared to the east due to a lack of S-bearing bedrock, higher groundwater recharge rates, thinner glacial sediments, and increased groundwater circulation. Focusing on a region in south-central Alberta (Red Deer area), hydrogeological characteristics relating to SO4 formation, recharge, permeability, hydraulic gradient, and travel time are included in a principal component analysis to identify six groundwater groups at varying stages of evolution and SO4 concentrations depending on their hydrogeological setting. Low SO4 concentrations are associated with areas of high recharge, where SO4 has been leached from the sediments, or with more evolved bedrock groundwater where SO4 has been reduced or was recharged in pre-glacial times. High SO4 concentrations are found in areas of lower recharge and permeability, where flushing occurs more slowly. Combining the Red Deer area and province-wide analyses, we identify seven regions across Alberta with characteristic distribution and controls on SO4 occurrence in shallow groundwater.

Synthesis of low-temperature NH3-SCR catalysts for MnOx with high SO2 resistance using redox-precipitation method with mixed manganese sources

It remains a big challenge to enhance the SO2 resistance of catalyst in low-temperature NH3-SCR reduction. In this work, a series of MnOx-a%Mn (a = 0, 1, 3, 5, 10) catalysts were prepared by introducing manganese acetylacetonate during the reaction between lactic acid and KMnO4, based on the molar ratio of manganese acetylacetonate to KMnO4. Notably, MnOx-5 %Mn exhibited more than 95 % NO conversion and 100 % N2 selectivity at 80–240 °C. Moreover, the catalyst demonstrated excellent sulfur resistance by sustaining over 90 % NO conversion at 140 °C at the presence of 100 ppm SO2 for more than 6 h. Furthermore, XPS characterization indicated that adding manganese acetylacetonate enhanced electron transfer efficiency and improved the reduction capacity of the catalyst due to the interconversion between Mn3+ and Mn4+, which improved electron transfer efficiency. The enhanced reduction capacity of the catalyst promoted the formation of oxygen vacancies and surface-adsorbed oxygen species (Oα), avoiding over-oxidation of NH3. The results elucidated that manganese acetylacetonate could optimize the overall performance by modulating the synergistic effect between the oxidizing ability and surface acidity of the catalyst. Therefore, the MnOx-5 %Mn catalyst possessed a broad operational temperature window (40–240 °C) and SO2 resistance in the NH3-SCR reaction, indicating its potential for practical application.

Engineering Nanoporous Polyaminal Networks for Superior SO2 Capture and Selectivity.

Designing adsorbent materials with high SO2 adsorption capacities and selectivity remains a significant challenge in flue gas desulfurization. This work focuses on developing two nitrogen-rich nanoporous polyaminal networks (NPANs), which demonstrate promising capabilities for SO2 adsorption and separation. Two nitrogen-rich nanoporous polyaminal networks, NPAN-5 and NPAN-6, were synthesized via a one-pot method using thiophene-2,5-dicarbaldehyde and furan-2,5-dicarbaldehyde with 1,4-bis(2,4-diamino-1,3,5-triazine)-benzene, respectively. The Brunauer-Emmett-Teller (BET) specific surface areas of NPANs range from 838 to 956 m2·g-1. At 298 K and pressures of 0.1 and 1.0 bar, NPAN-5, featuring thiophene units, demonstrates a SO2 adsorption uptake of 5.14 and 9.63 mmol·g-1, respectively, surpassing many previously reported materials. Furthermore, at room temperature, NPAN-6, containing furan moieties, exhibits unprecedented selectivity for SO2 over CO2 and N2, with ratios reaching up to 78 and 9321, respectively. Dynamic breakthrough experiments reveal that NPANs effectively separate SO2 from a ternary gas mixture comprising SO2, CO2, and N2 at concentrations of 0.2, 10, and 89.8%, respectively. Notably, NPAN-6 achieves a prolonged SO2 retention time of 218 min·g-1 and a saturation adsorption uptake of 0.42 mmol·g-1. The remarkable SO2 adsorption capacities and selectivities demonstrated by these nitrogen-rich nanoporous polyaminal networks underscore their potential to revolutionize industrial flue gas desulfurization.

Utilizing molecular simulation, ideal adsorbed solution theory and ensemble learning algorithms to investigate adsorption and separation of sulfides on amorphous nanoporous materials

Using grand canonical Monte Carlo method, we investigated the adsorption of pure H2S and SO2 gases on amorphous materials, and the separation of CH4-H2S and CO2-SO2 mixtures. At 303 K, the optimal adsorbent for both gases was found to be HCP-Colina-id016, with 16 mmol/g. For CH4-H2S mixture, despite aCarbon-Marks-id002 exhibiting the highest selectivity (approximately 80), the H2S adsorption was low (around 1 mmol/g), while Kerogen-Coasne-id013 demonstrated a high H2S adsorption of 12 mmol/g with a selectivity of 20. In the case of CO2-SO2, HCP-Colina-id018 exhibited a SO2 selectivity exceeding 30, with a high SO2 adsorption of 12 mmol/g. The Ideal Adsorbed Solution Theory underestimated the adsorption and selectivity of both mixtures, particularly evident in CO2-SO2. Molecular simulations revealed that, for the CO2-SO2 system, CO2 underwent condensation, resulting in a sudden drop in the SO2 adsorption isotherm. However, IAST accurately predicted this abrupt change. Based on the adsorption data obtained from molecular simulations, we compared the predictive performance of four ensemble learning algorithms, namely Random Forest (RF), Gradient Boosted Decision Trees (GBDT), Extreme Gradient Boosting (XGBoost), and CatBoost, for H2S and SO2 pure gases in amorphous porous materials. The rankings were observed to be XGBoost > GBDT > RF > CatBoost.

Design of Cu-based MIL-100(Fe) catalyst for propylene-selective catalytic reduction of NOx: Combination of activity, characterizations and mechanism

The hydrothermal technique was applied to prepare a new metal–organic framework, MIL-100(Fe), which was modified by ultrasonic impregnation with different wt % of copper. The results showed that the NOx conversion over 2.3Cu-MIL-100(Fe) was 100 % at 275 °C and maintained at ≥ 85 %, with N2 selectivity ≥ 90 % in the temperature range of 275–400 °C and high SO2 resistance. An increase in the Cu content up to 2.3 wt% showed the highest surface area (1206 m2/g) observed in N2 adsorption–desorption. The results show that the introduction of Cu increased the oxygen vacancies on the catalyst surface. Electron transfer and a synergistic effect were observed between Cu and Fe. The shift of the reduction peaks to lower temperatures after the addition of Cu confirmed that Cu improved the reducibility of the catalysts. The 2.3Cu-MIL-100(Fe) exhibited the highest Lewis content (44.97 μmol/g), which functions as an active site for the selective catalytic reduction (SCR) reaction. By precisely controlling the acid-base properties of the catalyst, the specificity for the desired products can be increased in complicated reaction systems, especially in hydrocarbon-SCR technology.

Porphyrin-based schiff-base and aminal nitrogen-rich porous organic polymers for capture of SO2 and CO2

Due to its serious hazards to human health and the environment, the deep removal of sulfur dioxide (SO2) has been of great significance. Thus, it is critical to develop high efficient SO2 capture and sequestration materials in gas purification process. Herein, we reported two novel prophyrin-based nitrogen-rich porous organic polymers (POPs), PrPOA-BP and PrPSN-BP, constructed through the simple catalyst-free condensation reaction. Owing to the strong affinity to SO2 from the conjugate-electron macrocycles structure of prophyrin and nitrogen-rich porous networks, also the high porous structure, these two POPs demonstrated excellent SO2 capture and separation performance with the adsorption uptakes up to 18.2 mmol g−1 (273 K, 1 bar), 13.3 mmol g−1 (298 K, 1 bar), 1.68 mmol g−1 (298 K, 0.01 bar). This very competitive performance has far exceeded most of the prior reported nanoporous materials. Meanwhile, the IAST selectivities of SO2/CO2 (10/90, v/v) could reach 107.8 and 72.0 at 273 and 298 K, 1 bar. This study represents a new type prophyrin-based POPs materials and confirms the intrinsic potential for high efficiency SO2 capture and sequestration.

Monometallic/Bimetallic Co‐ZIFs Synthesis, Characterization, and Application for Adsorption of SO2 and CO2 in Continuous Flow System

ABSTRACTSulfur dioxide is serious ultimatum to human health as well as environment, while carbon dioxide is viewed as one of the primary drivers of the worldwide temperature alteration. Therefore, capturing of these gases is a dynamic research subject attracting much consideration from scientists. Herein, we report synthesis of a series of Co‐ZIF and bimetallic M‐Co‐ZIF adsorbents and application for room temperature adsorption of SO2 and CO2. In this work, the breakthrough curves for the adsorption of sulfur dioxide and carbon dioxide on Co‐ZIF and M‐Co‐ZIF were obtained experimentally and theoretically using a laboratory‐scale fixed bed column at room temperature. In this work, the adsorption capacities and breakthrough points for modified bimetallic M‐Co‐ZIF were found to be relatively higher than parent Co‐ZIF. Notably, a high SO2 uptake capacity of 7.1 mmol/g for Zr‐Co‐ZIF and high CO2 uptake capacity of 69.9 mmol/g for Ni‐Co‐ZIF were achieved. The parent cobalt and bimetallic ZIF materials were characterized by XRD, FTIR, SEM, and nitrogen physisorption. The XRD results confirm the formation of pure phase highly crystalline ZIF materials while BET analysis suggests high surface area of prepared adsorbents. Finally, the results of dynamic adsorption combined with characterization show great potential for preparation of bimetallic ZIF adsorbents for effective SO2 and CO2 adsorption.

Response of sulfate concentration to eutrophication on spatio-temporal scale in freshwater lakes

The dramatical increase of sulfur concentration in eutrophic lakes, especially sulfate (SO42−), has brought attention to the impact on the lake ecosystem; however, the mechanisms driving the intensification of eutrophication and the role of SO₄2− concentrations remain poorly understood. To assess the impact of eutrophication on SO42− dynamics in lakes, this study monitored SO42− concentrations in water and sediments across seven lakes with varying trophic statuses on a spatial scale, and in the eutrophic Lake Taihu over one year on a temporal scale, as well as a series of microcosms with different initial SO42− concentrations. Exogenous sulfur input is the primary driver of increased SO42− concentrations in lakes, the highest SO42− concentration in overlying water was 100 mg/L, as well as which reached 310.9 mg/L in sediment. The concurrent input of nutrients such as nitrogen and phosphorus exacerbated eutrophication, resulting in the destabilization of the sulfur cycle. Eutrophication promoted the SO42− concentration on the spatio-temporal scale, especially in sediment, and trophic lake index (TLI) showed a positive correlation with the SO42− in sediments (R2 = 0.99; 0.88). The SO42− concentration in water and TLI showed a nonlinear correlation on the temporal scale (R2 = 0.44), and showed a positive correlation on the spatial scale (R2 = 0.49). Microscopic experiments demonstrate that the anaerobic environment created by cyanobacteria decomposition induced sulfate reduction and significantly reduces SO42− concentrations. Concurrently, the anaerobic environment facilitates the coupling of iron reduction with sulfate reduction, leading to a substantial increase in Acid Volatile Sulfides (AVS) in the sediment. These findings reveal that eutrophication has a dual effect on the dynamic change of SO42− concentrations in overlying water, which is helpful to accurately evaluate and predict the change of SO42− concentrations in lakes.

PM2.5 estimation and its relationship with NO2 and SO2 in China from 2016 to 2020

ABSTRACT The distribution of surface particulate matter (PM2.5) exhibits significant spatiotemporal patterns, especially with a spatial clustering effect. Therefore, resolving spatial characteristics is essential in the modeling process. This study proposes a space–time varying coefficients (STVC-LG) model by considering spatial effects from the perspective of eigenvector spatial filtering and incorporating spatial effects and temporal features into the LightGBM model to estimate ground PM2.5. A site-based cross-validation result of the estimated daily 1 km PM2.5 concentration in China from 2016 to 2020 shows that the proposed model offers high accuracy, an R2 of 0.88, and an RMSE of 12.21 μg/m3 (17% and 32% enhanced compared to the original LightGBM model). It uses a series of spatial eigenvectors to describe different spatial patterns. It then constructs spatial interaction terms by combining the eigenvectors and influencing variables, allowing the values of the variable to vary spatially with the eigenvectors. The obtained PM2.5, with a decreasing trend, had a clear distributional consistency with NO2 and SO2 according to the co-occurrence distribution maps, particularly in winter. In areas where high concentrations co-occur, both NO2 and SO2 concentrations are Granger-causing PM2.5 concentrations from a statistical perspective.

Springs of the Arabian Desert: Hydrogeology and Hydrochemistry of Abu Jir Springs, Central Iraq

The Arabian Desert is characterised by very low rainfall and high evaporation, yet over 210 springs are on its northeastern edge in central Iraq along the Abu Jir lineament, which represents the western depositional margin of a foreland basin infilled by the floodplain sediments of the Tigris and Euphrates Rivers; there is little evidence of faulting. The springs discharge from gently east-dipping Paleocene–Eocene limestones, either where groundwater flowpaths intersect the ground surface or where groundwater flow is forced to the surface by confining aquitards. Calculated annual recharge to the aquifer system across the Arabian Desert plateau (130–500 million m3) is significant, largely due to rapid infiltration through karst dolines, such that karst porosity is the primary enabler of groundwater recharge. The recharge is enough to maintain flow at the Abu Jir springs, but active management of groundwater extraction for agriculture is required for their long-term sustainability. The hydrochemistry of the springs is determined by evaporation, rainfall composition (high SO4 concentrations are due to the dissolution of wind-blown gypsum in rainfall), and plant uptake of Ca and K (despite the sparse vegetation). Limestone dissolution has relatively little impact; many of the springs are undersaturated with respect to calcite and lack tufa/travertine deposits. The springs at Hit-Kubaysa contain tar and high levels of H2S that probably seeped upwards along subvertical faults from underlying oil reservoirs; this is the only location along the Abu Jir lineament where deep-seated faults penetrate to the surface. The presence of hydrocarbons reduces the Hit-Kubaysa spring water and converts the dissolved SO4 to H2S.

Experimental study and chemical equilibrium calculation on the mineral transformation of high-alkali coal under oxy-fuel condition

The study aimed to study the mineral transformation of high-alkali coal to address the ash-related issues in oxy-fuel combustion. However, the traditional ashing method alone is inappropriate to study the mineral transformation at the initial stage of coal combustion due to the high ashing temperature. Hence, both the plasma ashing method (<200 °C) and traditional ashing method (600–1200 °C) were employed in this research to prepare the ash samples for characterization. The plasma ashing method is an efficient way to determine the original minerals in coal because it can consume the organic matter at low temperature. The recirculation of flue gas in oxy-fuel combustion can lead to high SO2 and H2O concentrations, while their influences on mineral transformation need to be clarified. In this work, SO2 and H2O were injected into CO2 to simulate the recycled flue gas (RFG). Furthermore, the chemical equilibrium calculation was conducted besides multiple experimental tests to acquire more comprehensive information of mineral transformation. The results show that high sodium and calcium contents are determined in these high-alkali coals, and two of them are rich in iron. In O2/CO2 atmosphere, some sodium (e.g. NaCl) volatilizes into the gas phase and the others converts into aluminosilicates (e.g. NaAlSi3O8) during the heating process. The calcium salts (mainly CaCO3 and CaSO4) decompose and produce silicates, aluminosilicates, and magnesium silicates. The major iron-containing minerals are identified as FeS, FeS2, and Fe2O3. Both FeS and FeS2 are oxidized into Fe2O3 below 600 °C. Moreover, the kaolinite (Al2Si2O5(OH)4) in raw coals decomposes at low temperature (<600 °C). In O2/RFG atmosphere, the additions of SO2 and H2O enhance the sulfation of AAEMs (alkali and alkaline earth metals) and delay the decomposition of sulfates. The productions of some silicates, aluminosilicates, and magnesium silicates of AAEMs are inhibited to varying degrees, and there could be complicated salts containing sulfur (e.g. hauyne). The transformations of iron-containing minerals are little related to the presences of SO2 and H2O. This work obtained the transformations of main minerals in high-alkali coal under O2/CO2 and O2/RFG conditions, which helps to address the ash-related issues.

Trend of SO2 Gas Dry Deposition in Vietnam

This research used the calculating method of dry deposition to estimate SO2 dry deposition value and evaluate its trend in 5 recent years. The results indicate that SO2 emission at Northern sites is more changing than Southern ones in months by affecting meteorology and weather. Summer and autumn seasons have SO2 emitted concentrations higher than other seasons in 2019, 2020, and 2022 year at Yen Bai, Hoa Binh, and Ha Noi stations. The 2021 year has the highest SO2 dry deposition and the 2019 year has the lowest SO2 dry deposition in 5 recent years. The Hanoi site has the highest SO2 dry deposition value from 2019 to 2022 year. Hoa Binh site has the highest SO2 dry deposition at 2.45 kg/ha/year in 2023. High SO2 dry deposition occurs normally in the summer and autumn (from April to August). Southern sites have lower SO2 dry deposition amounts with not much change than the Northern sites of Vietnam. The increasing trend of SO2 dry deposition happened from 1999 to 2023 year and it increases sharply from 1999 to 2021. Therefore, SO2 dry deposition will have a light-increasing trend in the future.

Efficient separation of vanadium and chromium by the complexation with sulfate ions in solvent extraction using EHEHPA

The significant chemical similarity between vanadium and chromium complicates the process of efficient extracting V(Ⅳ) from the solution containing Cr(Ⅲ) to prepare high-purity vanadyl sulfate electrolyte. In this study, the separation of vanadium and chromium with 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (EHEHPA) was enhanced by increasing the concentration of SO42−. Under the extraction equilibrium pH of 2.5, the extraction of Cr(III) was suppressed by increasing the concentration of SO42− anions, which hardly affected the extraction efficiency of V(IV), achieving a separation factor as high as 5780.6 at SO42− concentration of 1.75 mol·L−1. Furthermore, after pretreatment of the water-leaching solution of sodium-roasted vanadium slag, extraction was carried out under the conditions of equilibrium pH of 1.8 and SO42− concentration of about 2.00 mol·L−1, and after stripping, the vanadyl sulfate electrolyte containing 2.12 mol·L−1 of vanadium and only 0.11 mg·L−1 of chromium was obtained. It was proved that Cr(Ⅲ) mainly extracted in the form of CrSO4+ into organic phase by one EHEHPA dimer as [CrSO4(H2O)]+ under higher SO42− concentrations (e.g., ≥1.50 mol·L−1), while Cr(Ⅲ) was extracted by two EHEHPA dimers as Cr3+ without SO42− in the solution. Based on the density functional theory, the complex structures of Cr(III) were optimized and the energy changes of Cr(III) extraction reactions were calculated, indicating the complexation between SO42− and Cr(III) under higher SO42− concentrations resulting in the inhibition of Cr(III) extraction, and thus enhancing the separation of vanadium and chromium.

Surface-air exchanges of H2S and SO2 in an urban wetland in eastern China

Wetlands are widely recognized as hot spots for the emission or deposition of biogenic sulfur gases, including hydrogen sulfur (H2S) and sulfur dioxide (SO2), which significantly affect air quality and climate change. With the expansion of urban wetlands, it is critical to know the roles that urban wetlands played in atmospheric H2S and SO2 budget. In this study, the surface-air exchange fluxes of H2S and SO2 were measured by the Dynamic Flux Chamber (DFC) method in a typical urban wetland in eastern China from Sep 2022 to July 2023. It was found that the urban wetland did not have the expected high H2S emission, might be caused by the relatively high pH value and low sulfate concentration in the soil. Although H2S showed emission in the daytime of spring and summer, an overall H2S flux of −0.04 kg S ha−1 yr−1 was observed throughout the year. Meanwhile, the urban wetland presented a net sink of SO2, with a deposition flux of 0.14 kg S ha−1 yr−1. The negative peaks of SO2 flux corresponded to the suddenly elevated SO2 concentration in the ambient air especially in spring and winter. Through linear fitting of SO2 flux and concentration, the concept of SO2 “compensation point” was proposed. The compensation point is the concentration level at which the observed SO2 flux equals zero. The “compensation point” changed with the season and was related to temperature and humidity. The “compensation point” in summer and autumn were larger, being 2.37 ppb and 1.40 ppb, respectively, while they were 1.07 ppb and 0.86 ppb in spring and winter respectively. Our results suggest that the urban wetland expansion may have little risk of increasing air H2S but could act as a significant sink of SO2 with high SO2 concentration in the urban region.

Identification and Expression Analysis of Sulfate Transporter Genes Family and Function Analysis of GmSULTR3;1a from Soybean.

Sulfate transporters (SULTRs) are essential for the transport and absorption of sulfate in plants and serve as critical transport proteins within the sulfur metabolism pathway, significantly influencing plant growth, development, and stress adaptation. A bioinformatics analysis of SULTR genes in soybean was performed, resulting in the identification and classification of twenty-eight putative GmSULTRs into four distinct groups. In this study, the characteristics of the 28 GmSULTR genes, including those involved in collinearity, gene structure, protein motifs, cis-elements, tissue expression patterns, and the response to abiotic stress and plant hormone treatments, were systematically analyzed. This study focused on conducting a preliminary functional analysis of the GmSULTR3;1a gene, wherein a high expression level of GmSULTR3;1a in the roots, stems, and leaves was induced by a sulfur deficiency and GmSULTR3;1a improved the salt tolerance. A further functional characterization revealed that GmSULTR3;1a-overexpressing soybean hairy roots had higher SO42-, GSH, and methionine (Met) contents compared with the wild-type (WT) plant. These results demonstrate that the overexpression of GmSULTR3;1a may promote the sulfur assimilation metabolism and increase the content of sulfur-containing amino acids in plants.

Acid sites-CeOx doping CrZrCeOx catalyst with high SO2 resistance for marine SCR application: Surface analysis and mechanism study

This paper mainly talked about acid sites-CeOx doping CrZrCeOx catalyst with high SO2 resistance for marine NH3– SCR (selective catalytic reduction). The NO removal efficiency of the Cr:Zr:Ce = 8:2:1 catalyst reached 90 % with 500 ppm SO2 and 85 % with 1000 ppm SO2 for 20 h, respectively. It was inferred that the main roles of CeOx species were acid sites but not redox sites. CeOx addition promoted the SCR performance and SO2 resistance, which significantly changed the adsorbed species on the surface. CeOx acted as sacrifice sites to protect CrOx actives sites through reducing the combination of Cr and sulfates. The Cr:Zr:Ce = 8:2:1 catalyst followed Langmuir-Hinshelwood (L-H) mechanism and the reaction process was derived in this paper. It indicated that the Cr:Zr:Ce = 8:2:1 catalyst would be a promising marine SCR catalyst with good SO2 resistance in the future.

Triple Templates Directed Synthesis of Nitrogen-Doped Hierarchically Porous Carbons from Pyridine Rich Monomer as Efficient and Reversible SO2 Adsorbents.

Herein, a variety of 2,6-diaminopyridine (DAP) derived nitrogen-doped hierarchically porous carbon (DAP-NHPC-T) prepared from carbonization-induced structure transformation of DAP-Zn-SiO2-P123 nanocomposites are reported, which are facilely prepared from solvent-free co-assembly of block copolymer templates P123 with pyridine-rich monomer of DAP, Zn(NO3)2 and tetramethoxysilane. In the pyrolysis process, P123 and SiO2 templates promote the formation of mesoporous and supermicroporous structures in the DAP-NHPC-T, while high-temperature volatilization of Zn contributed to generation of micropores. The DAP-NHPC-T possess large BET surface areas (≈956-1126 m2g-1), hierarchical porosity with micro-supermicro-mesoporous feature and high nitrogen contents (≈10.44-5.99 at%) with tunable density of pyridine-based nitrogen sites (≈5.99-3.32 at%), exhibiting good accessibility and reinforced interaction with SO2. Consequently, the DAP-NHPC-T show high SO2 capacity (14.7mmolg-1, 25°C and 1.0bar) and SO2/CO2/N2 IAST selectivities, extraordinary dynamic breakthrough separation efficiency and cycling stability, far beyond any other reported nitrogen-doped metal-free carbon. As verified by in situ spectroscopy and theoretical calculations, the pyridine-based nitrogen sites of the DAP-NHPC-T boost SO2 adsorption via the unique charge transfer, the adsorption mechanism and reaction model have been finally clarified.