Sulfide Formation Research Articles

Isoindolium-Based Allenes: Reactivity Studies and Applications in Fluorescence Temperature Sensing and Cysteine Bioconjugation.

The reaction of a series of electron-deficient isoindolium-based allenes with sulfhydryl compounds has been studied, leading to the formation of isoindolium-based vinyl sulfides. The vinyl sulfides generated could be readily converted into the corresponding indanones and amines upon heating at 30-70 °C with good yields up to 61 %. The thermal cleavage reaction of vinyl sulfides was further studied for developing temperature-sensitive systems. Notably, a novel FRET-based fluorescent temperature sensor was designed and synthesized for temperature sensing at 50 °C, giving a 6.5-fold blue fluorescence enhancement. Moreover, chemoselective bioconjugation of cysteine-containing peptides with the isoindolium-based allenes for the construction of multifunctional peptide bioconjugates was investigated. Thermal cleavage of isoindoliums on the modified peptides at 35-70 °C gave indanone bioconjugates with up to >99 % conversion. These results indicated the biocompatibility of this novel temperature-sensitive reaction.

Phytoremediation of Acid Mine Drainage with Melaleuca cajuputi, Nauclea orientalis, and Vetiveria zizanioides in Floating Treatment Wetland

The formation of acid mine drainage (AMD) is a common environmental problem in the mining industry. Its passive management through wetland construction has gained more consideration in recent years. However, the application in the field is constrained by the large area and relatively shallow depth. Indonesia has no passive technology to neutralize AMD in deep water. One solution is to apply a floating treatment wetland (FTW) system. Therefore, this study aimed to determine the ability of several hyperaccumulator plants, such as Melaleuca cajuputi, Nauclea orientalis, and Vetiveria zizanioides, to neutralize AMD using a floating system by conducting FTW trials. The method used was a Completely Randomized Design (CRD) with 3 treatments and control/without plants. Each treatment had 3 replications, resulting in 12 experimental units. The results showed that the FTW with or without plants could increase pH and decrease dissolved Mn by 75.31-90.74%. Heavy metals were chelated by organic matter, absorbed by plants, and deposited in the form of metal sulfides. The results also indicated that besides having a positive effect on pH and heavy metal reduction, the organic-based floating wetland increased biological oxygen demand (BOD) from 61.08-79.71%.

Carbothermal reduction synthesis of sulfide-modified biochar for heavy metal removal

Although sulfide is effective for heavy metal immobilization, it rarely exists in pristine pyrogenic biochar and easily undergoes intensive hydrolysis. In this work, carbothermal reduction of sulfate for on-site sulfide formation and simultaneous carbon layer encapsulation was developed to synthesize sulfide (CaS) modified biochar for enhancing heavy metal immobilization capacity. The initial reaction temperature for this carbothermal reduction was 700 °C. Increasing the pyrolysis temperature, modifier electron accepting ability and loading content could facilitate carbothermal reduction as further partly confirmed by on-site MS of pyrolysis gas and S 2p XPS of biochar analysis. The formed CaS on biochar could be greatly inhibited from hydrolysis due to the encapsulation effect of carbon layer and reached nearly 100% utilization efficiency in Cd2+ fast immobilization. TEM line scan and XRD of post-adsorbed biochar indicated that high heavy metal immobilization capacity was mainly attributed to the coprecipitation reaction governed by the formation of metal-sulfur bond. Compared with reported absorbents, CaS-modified biochar via carbothermal reduction with on-site encapsulation exhibited an excellent stability and outstanding immobilization capacity for various heavy metal ions (such as Cd2+, Pb2+, Cu2+, Zn2+, Ag+).Graphical

Stainless Steels for Plastic Mold Frames Featuring Enhanced Machinability

Steels for the production of frames for plastic molds frequently need to exhibit resistance to corrosion while at the same time requiring large amounts of machining. Machinability as a crucial property can be enhanced by the addition of sulfur, resulting in the formation of favorable sulfides, which in turn can deteriorate mechanical properties and corrosion resistance. The detrimental effect on mechanical properties is caused, among others, by the elongation of sulfides during rolling or forging. In a novel approach, a special wire treatment of the melt is performed, which results in improved spherical morphology and chemical composition of the inclusions, yet leading to even enhanced machinability (tested, among others, by means of milling). Milling tests reveal increased productivity compared to conventionally manufactured material, which means an improved lifetime of milling inserts even at the highest cutting speeds. In addition, orthogonal cutting trials are performed aiming at understanding differences in machinability. At the same time, mechanical properties, in particular toughness, are slightly improved, while corrosion resistance is not severely affected.

Brazilian basins characterization based on the distributions of elements in desalted crude oils using classical multivariate analysis and kohonen self-organizing map

The classification of petroleum regarding origin is usually carried out by Ni, V, and S correlations because these elements are essentially present in the oil phase. In contrast, other elements can be partitioned with the water phase. In this work, extraction of the water-soluble elements was performed on 70 crude oil samples from six Brazilian Basins. Both original and washed oils were analyzed for their metal concentrations by inductively coupled plasma mass spectrometry (ICP-MS) after microwave-assisted acid decomposition of the matrix. Then, Spearman's correlation between the original and washed oils showed element partitioning. The association of elements in the washed oils was used to avoid repetitive information by reducing the number of variables. Principal components analysis, which is a commonly employed multivariate technique, was applied to the reduced matrix, but Basin's separation was not possible because of the poor contribution (50%) of PC1 and PC2 to the variance. Then, the Kohonen self-organizing map (KSOM) artificial neural network was performed on the same matrix, with a 5x5 hexagonal topology based on Euclidean distance, resulting in a more robust analysis. The proposed data treatment allowed the association of Mo, Re, and V with marine anoxic origin, while Co, Ni, and Ce concentrations increased in petroleum from terrestrial oxic origin, and Basins were separated regarding the occurrence of these elements. Other metals such as Cu, Fe, Mn, and Zn were not significant for the classification of Basins possibly due to other geochemical processes such as the formation and oxidation of sulfides.

Molecular and experimental study on hydrogen sulfide formation mechanism during Chang 7 type-II oil shale kerogen pyrolysis

Hydrogen sulfide is a volatile toxic gas associated with oil and gas production, causing corrosion to surface equipment such as wellbores and doing harm to the environment. This study aims to investigate the formation mechanism of hydrogen sulfide during the pyrolysis process of Chang 7 type-II oil shale kerogen. XPS spectra are obtained with the usage of Kratos Analytical Axis UltraDLD to analyze the occurrence forms of hybrid atoms. S 2p XPS spectrum and its fitted curves are gained from full spectrum wide spectrum scanning and narrow spectrum scanning of the sulfur element. The pyrolysis characteristics and processes of kerogen with three initial structures under different temperatures are implemented with ReaxFF. The results of the hydrogen sulfide formation pathway are tracked. The sulfur element in Chang 7 II kerogen is mainly in the form of organic sulfur, with a molar ratio of 77.74%. The kerogen initial structure with fewer CC bonds containing more H atoms has a higher oil yield. The desulfurization rate sharply increases with the increase in pyrolysis temperature. Hydrogen sulfide production is affected by sulfur-containing functional groups (aliphatic sulfur, aromatic sulfur, sulfoxide, sulfone). Hydrogen sulfide formation paths mainly include capturing H radicals through HS radicals and capturing H radicals through high sulfur to form -SH2-.

Cysteine-Induced pH-Dependent Formation of Thiols and Sulfides or 2-Acetylthiazole and Pyrazines during Thermal Treatment of N-(1-Deoxy-d-xylulos-1-yl)-alanine

The influence of pH was studied on volatile flavor formation during thermal treatment of an Amadori rearrangement product (ARP) with or without the addition of cysteine (Cys). The formation of thiols and sulfides or 2-acetylthiazole and pyrazines induced by Cys during thermal degradation of ARP was pH-dependent. At low pH levels, the hydrolysis of Cys to hydrogen sulfide (H2S) was promoted, giving rise to the increase of thiols and sulfides with an obvious meaty aroma. However, alkaline conditions were beneficial for enhancing the cyclization or transformation of imine to the enol structure, which strengthened the formation of 2-acetylthiazole and pyrazines with a roasted and nutty aroma. The imine was derived from the nucleophilic addition of Cys and methylglyoxal (MGO) and subsequent decarboxylation. At pH 8, Cys-induced variation of the flavor profile was weakened during thermal degradation of ARP. Accordingly, the combinational effect of pH and added Cys could be beneficial for achieving the desirable flavors during thermal processing of ARP.

Magnetic properties of gas hydrate-bearing sediments and their association with iron geochemistry in the Sea of Marmara, Turkey

The anaerobic oxidation of methane, a key geochemical process that is involved in the cycling of sulfate and iron (oxyhydr)oxides in marine sediments, results in the formation of iron sulfides. Although ferrimagnetic iron sulfides have been identified in seepage systems, the link between iron migration and sediment magnetic properties remains poorly understood. Here, we investigate two cores from the Sea of Marmara to evaluate biogeochemical iron cycling and iron sulfide mineralogy in gas hydrate-bearing sediments. Magnetic analyses indicate the presence of greigite and pyrrhotite in a core from a hydrate-rich site with a high hydrocarbon flux, which contrasts with a lack of these minerals in a core characterized by only mild seepage. This is supported by the results of rock magnetic and scanning electron microscope analyses of the sediments. The presence of authigenic greigite is critical for assessing local redox records and together with the occurrence of monoclinic pyrrhotite may suggest specific diagenetic processes in gas hydrate environments. Our analysis demonstrates the usefulness of these ferrimagnetic minerals, with a high saturation isothermal remanent magnetization to magnetic susceptibility ratio (SIRM/χ > 15 kAm−1) and a high index of hysteresis parameters (DJH > 0.2) indicative of magnetic mineralogy changes, for evaluating variability in the intensity of seepage fluxes and for estimating gas hydrate distributions.

Geochemical Modeling of Heavy Metal Removal from Acid Mine Drainage in an Ethanol-Supplemented Sulfate-Reducing Column Test.

A passive treatment process using sulfate-reducing bacteria (SRB) is known to be effective in removing heavy metals from acid mine drainage (AMD), though there has been little discussion of the mechanism involved to date. In this work, a sulfate-reducing column test was carried out using supplementary ethanol as an electron donor for microorganisms, and the reaction mechanism was examined using geochemical modeling and X-ray absorption fine structure (XAFS) analysis. The results showed that Cu was readily removed from the AMD on the top surface of the column (0-0.2 m), while Zn and Cd depletion was initiated in the middle of the column (0.2-0.4 m), where sulfide formation by SRB became noticeable. Calculations by a developed geochemical model suggested that ethanol decomposition by aerobic microbes contributed to the reduction of Cu, while sulfide produced by SRB was the major cause of Zn and Cd removal. XAFS analysis of column residue detected ZnS, ZnSO4 (ZnS oxidized by atmospheric exposure during the drying process), and CuCO3, thus confirming the validity of the developed geochemical model. Based on these results, the application of the constructed geochemical model to AMD treatment with SRB could be a useful approach in predicting the behavior of heavy metal removal.

Effect of carbon dioxide on oxy-fuel combustion of hydrogen sulfide: An experimental and kinetic modeling

CO2 is an important component in the acid gas and it is necessary to study the effect of CO2 presence on the oxy-fuel combustion of H2S with particular focus on the formation of carbonyl sulfide (COS). The oxy-fuel combustion of acid gas was conducted in a coaxial jet double channel burner. The distribution of flame temperature and products under stoichiometric condition along axial (R = 0.0) and radial at about 3.0 mm (R = 0.75) were analyzed, respectively. The Chemkin-Pro software was used to analyze the rate of production (ROP) for gas products and the reaction pathway of acid gas combustion. Both experimental and simulation results showed that acid gas combustion experienced the H2S chemical decomposition, H2S oxidation and accompanied by H2 oxidation. The CO2 presence reduced the peak flame temperature and triggered the formation of COS in the flame area. COS formation at R = 0.0 was mainly through the reaction of CO2 and CO with sulfur species, whereas at R = 0.75 it was through the reaction of CO with sulfur species. The ROP results indicated that H2 was mainly from H2O decomposition in the H2S oxidation stage, and COS was formed by the reaction of CO2 with H2S. ROP and other detailed analysis further revealed the role of H, OH and SH radicals in each stage of H2S conversion. This study revealed the COS formation mechanisms with CO2 presence in the oxy-fuel combustion of H2S and could offer important insights for pollutant control.

Sulfur transformation mechanism during supercritical water gasification of black liquor

Supercritical water gasification (SCWG) was a promising technology to treat black liquor harmlessly and recycle energy efficiently, while the sulfur transformation of black liquor during SCWG process remained unknow. Herein, the effects of different parameters on gasification and sulfur transformation was determined in a batch reactor. The results showed that reaction temperature played the most important role. H2 was the most important gaseous product with the maximum yields of 19.01 mol·kg−1, simultaneously achieving the highest carbon gasification efficiency (95.16 %), COD removal rate (99.98 %) and the pH of 8.5 at 700 °C, 30 min and 25 MPa. After SCWG treatment, most of sulfur existed in the form of sulfide (H2S/S2−), and the maximum proportion of which was up to 90.51 % at 700 °C, 30 min and 25 MPa. With the increase in temperature, the organic sulfur (thiol/thioether, sulfone and thiophene) and inorganic sulfur (sulfate and thiosulfate) were transformed into sulfide (H2S/S2−). Finally, the sulfur transformation mechanisms of black liquor in SCWG were proposed. This work provided a basis for resource utilization of black liquor and a promising method for sodium sulfide production.

Sulfur-resistant MoO2/TS-1 zeolite armored PdCu alloy composite membrane for hydrogen separation under H2S containing steam

Sulfur poisoning could result in fast deterioration of Pd-based membranes by the formation of metal sulfides and reduction of hydrogen purity. The introduction of an MoO2/TS-1 layer could provide an effective protection of the Pd layer. Therefore, in this paper a synthetic method is presented for preparation of sulfur-resistant MoO2/TS-1 zeolite modified PdCu alloy composite membranes and their application in hydrogen separation under H2S containing steam. According to the stability test results, the MoO2/TS-1 zeolite armored layer obviously prolonged the stability of Pd based membrane. After 50 h stability test with 100 ppm H2S, there were no obvious structural changes and metal sulfide formation detected in the PdCu bulk from SEM images and XRD patterns, indicating that MoO2/TS-1 armor structure was good enough for protecting the PdCu alloy bulk.

Isothiocyanates (in situ) and sulfonyl chlorides in water for N-functionalization of bicyclic amidines: access to N-alkylated γ-/ω-lactam derivatized thiourea and sulfonamides.

Herein, we showcase the potential of isothiocyanates generated in situ and aryl sulfonyl chlorides as electrophiles in water for N-functionalization of bicyclic amidines (DBN and DBU). This strategy provides complementary access to a range of thiouredosulfides, sulfonamides, aroylthioureas and amides derivativatized with distal γ- and ω-lactams. A novel sulfonyl chloride mediated formation of β-uredo sulfides has been achieved from β-isothiocyanato sulfides, removing the requirement for the harsh synthesis of unstable isocyanates. Mechanistic studies suggest a radical mechanism for the difunctionalization of alkenes, the efficacy of H2O in the ring opening of bicyclic amidines, and an oxygen source along with sulfonyl chloride as desulfurization agents for thiourea to afford urea derivatives.

Effect of Ga substitution with Al in ZSM-5 zeolite in methanethiol-to-hydrocarbon conversion.

The catalytic properties of conventional H-[Al]-ZSM-5 and gallium-substituted H-[Ga]-ZSM-5 were evaluated in the conversion of methanethiol to ethylene (CH3SH → 1/2C2H4 + H2S). Dimethyl sulfide (DMS), aromatics, and CH4 were formed as byproducts on the H-[Al]-ZSM-5 catalyst. The introduction of Ga into the ZSM-5 structure provided a high ethylene yield with relatively high selectivity for olefins. Based on the temperature-programmed desorption of NH3 and pyridine adsorption on zeolites, the strength of acid sites was decreased by introducing Ga into the ZSM-5 structure. Undesirable reactions seemed less likely to occur at weakly acidic sites. The suppression of the formation of dimethyl sulfide (CH3SH → 1/2C2H6S + 1/2H2S) and the sequential reaction of ethylene to produce aromatics provided a high yield of ethylene over H-[Ga]-ZSM-5.

Anaerobic biodegradation of citric acid in the presence of Ni and U at alkaline pH; impact on metal fate and speciation

Biodegradation of citrate occurred under LLW repository relevant conditions with Ni and U present. Citrate biodegradation led to the formation of insoluble Ni sulfides or nanocrystalline U(iv)–phosphate and may promote Ni/U retention in LLW repositories.

Комплексная реагентная защита установки висбрекинга с целью увеличения межремонтного пробега

A detailed analysis of chemical reagents that are used in visbreaking units at oil refineries is presented. Additives have been identified that are used in a number of refineries, such as a passivator, coke inhibitor, dispersant, corrosion inhibitor, neutralizer, defoamer or antifoaming agent. The most vulnerable points of the visbreaking installation technology are considered. A diagram is presented with the designation of areas with possible problems, namely foaming of the oil product, contamination by coke deposits of equipment, corrosion of helmet lines, the possible formation of hydrogen sulfide and other undesirable components. A comprehensive review of each reagent allows you to understand its purpose at the facility, to understand the mechanisms of the action of reagents. The approximate compositions of each reagent are analyzed, the requirements for additives are considered.

Novel H2S sensing mechanism derived from the formation of oligomeric sulfide capping the surface of gold nanourchins.

A gold nanourchin (AuNU) probe with a novel sensing mechanism for monitoring H2S was developed as a feasible colorimetric sensor. In this study, AuNUs that are selectively responsive to H2S were fabricated in the presence of trisodium citrate and 1,4-hydroquinone using a seed-mediated approach. Upon exposure of the AuNU solution to H2S, the hydrosulfide ions (HS-) in the solution are converted into oligomeric sulfides by 1,4-hydroquinone used as a reducing agent during the synthesis of AuNUs. The oligomeric sulfides formed in the AuNU solution upon the addition of H2S were found to coat the surface of the AuNUs, introducing a blue shift in absorption accompanied by a color change in the solution from sky blue to light green. This colorimetric alteration by the capping of oligomeric sulfides on the surface of AuNUs is unique compared to well-known color change mechanisms, such as aggregation, etching, or growth of nanoparticles. The novel H2S sensing mechanism of the AuNUs was characterized using UV-Vis spectroscopy, high-resolution transmission microscopy, X-ray photoelectron spectroscopy, surface-enhanced Raman spectroscopy, secondary ion mass spectroscopy, liquid chromatography-tandem mass spectrometry, and atom probe tomography. H2S was reliably monitored with two calibration curves comprising two sections with different slopes according to the low (0.3-15 μM) and high (15.0-300 μM) concentration range using the optimized AuNU probe, and a detection limit of 0.29 μM was obtained in tap water.

Highly Sensitive, Rapid, and Real-Time Detection of Hydrogen Sulfide in Human Blood Plasma Using MoSe2 Field-Effect Transistor

Rapid and real-time hydrogen sulfide (H2S) detection in human blood or plasma is required as it has physiological and pathophysiological relations with human health. An ultrasensitive field-effect transistor (FET) using a layered transition metal dichalcogenides is demonstrated to detect dissolved H2S in plasma. The biosensor effectively utilizes a few layers of MoSe2 as a channel material for the FET device. The fabricated biosensor exhibited the highest response of 78 at the lowest H2S concentration of 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{M}$ </tex-math></inline-formula> and a wide linear dynamic range (between 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{M}$ </tex-math></inline-formula> and 1 mM). With the lowest detection limit of 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{M}$ </tex-math></inline-formula> , the fabricated biosensor is appropriate for quick and real-time detection of H2S in plasma for point-of-care applications. In the concentration range of 1–100 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{M}$ </tex-math></inline-formula> , the FET device shows linear change in its drain current and the threshold voltage. However, the fabricated device is still a proof of concept and could open new technological avenues for directly detecting all the forms of free sulfide in plasma with rapid, real-time, and stable sensing performance for point-of-care applications.

Hydrogen Sulfide Formation in Canned Wines Under Long-Term and Accelerated Conditions

<h3>Background and goals</h3> Wines in aluminum beverage cans (“canned wines”) are a rapidly growing packaging segment due to several factors, including convenience and sustainability advantages. However, canned wines have higher concentrations of hydrogen sulfide (H₂S; “rotten egg”) than wines in glass packaging. It was hypothesized that wine composition and liner selection affect H₂S formation in canned wines. <h3>Methods and key findings</h3> Commercial wines (n=10) were stored in either glass or aluminum beverage cans with one of three liners for up to 32 weeks. Wines stored in glass showed negligible H₂S production after 32 weeks. Wines stored in acrylic lined cans produced up to 1307 μg/L H₂S (median = 162 μg/L) within 8 weeks. Wines stored in BPA epoxy cans produced less H₂S (maximum = 51.8 μg/L median = 11.8 μg/L after 32 weeks), with comparable performance observed for BPA non-intent (BPA-NI) epoxy liners. H₂S formation was well-correlated with visible damage to the interior liners, but poorly correlated with dissolved aluminum. H₂S from accelerated aging of wines with lined aluminum coupons (50 ºC, up to 14 d, anoxic conditions) correlated with H₂S produced during long-term aging, but not with H₂S produced by unlined aluminum coupons. Molecular SO2 was best correlated with increased H₂S production in epoxy lined cans during long-term aging of commercial wines, and similar results were observed under accelerated conditions with coupons in a model-wine factorial experiment. <h3>Conclusions and significance</h3> Maintaining low molecular SO2 (less than ~0.4 mg/L) and using epoxy liners (BPA or BPA-NI) appear critical for ensuring low H₂S during long-term can storage up to 8 months. The accelerated aging approach described in this work may be applicable to other corrosive beverages.

Effect of nano and macro iron sprays on growth, flowering, seed and oil yielding attributes in calendula (Calendula officinalis L.)

The investigation was executed with nine treatments viz. nano forms of ferrous sulfide (7, 14, 21, 28 ppm) and macro ferrous sulphate (0.2, 0.4, 0.6, 0.8 per cent) along with control, and were applied as foliar sprays after 30 days of transplanting on two varieties of calendula namely Fiesta Gitana Mix’ and ‘Fiesta Yellow’ during 2018 and 2019. The experiment was laid out in factorial randomized block design with three replications. Application of 0.8 % FeSO4 recorded maximum number of branches (26.75), plant height (29.73 cm), plant spread (45.17 cm), number of leaves (22.63) and seed test weight (15.63 g) and number of flowers per plant (134.04). However, application of 0.2% macro FeSO4 resulted in early bud appearance (50.50 days) and higher flower diameter (8.09 cm). ‘Fiesta Gitana Mix’ outperformed over ‘Fiesta Yellow’ for most of the vegetative and floral characters. The ‘Fiesta Yellow’ variety with oil content (13.97%) had an edge over ‘Fiesta Gitana Mix’.