Different Concentrations Of H2S Research Articles

Unveiling the effect of H2S concentration in CH4 hydrate formation and growth: A molecular dynamics study

We used molecular dynamics method to simulate the formation and growth of CH4 hydrates with different concentrations of H2S. At the large scale of simulation time, 10000 ns, it is unlikely to form hydrates at 10 MPa and 260 K if there are only CH4 and water; and if there was a small proportion of H2S in the gas, hydrates would easily form. When the molar concentration of H2S in the gas is 1 %, the formed hydrate is unstable and will eventually disintegrate, leaving the box in a two-phase state of gaseous and liquid. In contrast, at molar concentrations of 5 % or higher of H2S, hydrate formation is accelerated, and the hydrate will grow continuously. However, it is not structure I type as expected. These views are supported by the changes in F3 and F4 order parameters, numbers of different cage types, and the number of water molecules belonging to different states. Moreover, since the formation of hydrates is an energy reduction process, we can easily develop inhibitors targeted at hydrates in actual production and gas transportation. According to IGMH analysis, only van der Waals interactions occur between gas molecules inside the cages and the water cage.

CuO nanostructure-decorated InGaN nanorods for selective H2S gas detection.

Establishing a heterostructure is one of the adequate strategies for enhancing device performance and has been explored in sensing, and energy applications. In this study, we constructed a heterostructure through a two-step process involving hydrothermal synthesis of CuO nanostructures and subsequent spin coating on MBE-grown InGaN NRs. We found that the CuO content on the InGaN NRs has a great impact on carrier injection at the heterojunction and thus the H2S gas sensing performance. Popcorn CuO/InGaN NR shows excellent gas sensing performance towards different concentrations of H2S at room temperature. The highest response is up to 35.54% to a H2S concentration of 100 ppm. Even more significantly, this response is further enhanced significantly (123.70%) under 365 nm UV light. In contrast, this composite structure exhibits negligibly low responses to 100 ppm of NO2, H2, CO, and NH3. The heterostructure band model associated with a surface reaction model is manifested to elucidate the sensing mechanism.

Ag@Fe3O4-coated U-shaped plastic optical fiber sensor for H2S detection

This work presents the fabrication of U-shaped plastic optical fiber (POF) sensors for hydrogen sulfide (H2S) detection, coated with Fe3O4 nanoparticles synthetized using the Pulsed Laser Ablation in Liquid (PLAL) technique. The Fe3O4 nanoparticles were synthetized in ultra-pure water and in silver nitrate solution, resulting in two colloidal samples with different morphological, optical, and structural properties. The Fe3O4 nanoparticles were coated onto one POF sensor, while the other sensor was coated with a nanostructure composed of Ag as the core and Fe3O4 as the shell (Ag@Fe3O4). The performance of both sensors was evaluated by exposing them to different concentrations of H2S and other gases such as CH4, H2, and CO2. All experiments were conducted at 25 °C. Results showed that the sensor coated with Ag@Fe3O4 was 12 times more sensitive to H2S compared to the sensor coated with Fe3O4, with a detection limit of 1 ppm and a rise time of 15 s. Moreover, the POF sensor coated with Ag@Fe3O4 presented high selectivity to H2S, making it a promising candidate for H2S detection in different applications. The sensor's performance was also evaluated with a relative humidity range of 20–90%, exhibiting a minimal 0.75% signal variation at 90% humidity.

Effect of H2S on biogas sorption enhanced steam reforming using a Pd/Ni-Co catalyst and dolomite as a sorbent

To achieve net zero carbon emissions from energy systems, biogas has become an attractive renewable resource for hydrogen production. The sorption enhanced steam reforming (SESR) process is proposed to produce high-purity hydrogen from biogas, enabled by combining the catalytic reforming reaction with the simultaneous CO2 removal by sorption in a single reactor. One of the most critical challenges in using biogas in conventional reforming processes is the presence of H2S since it may deactivate the reforming catalyst. Here we experimentally study the effect of the biogas H2S concentration on the H2 production by SESR, i.e., accounting for the presence of a CaO-based solid sorbent. This work was performed in a fixed-bed reactor using a Pd/Ni-Co hydrotalcite-like material (HT) catalyst and dolomite as CO2 sorbent. Biogas (60CH4/40CO2 vol.%) with different concentrations of H2S (150, 350, 500 and 1000 ppm) was evaluated. The catalyst did not deactivate for biogas H2S concentrations of 150 and 350 ppm during five cycles of the SESR process. However, a slight decrease in the catalyst activity was detected under higher sulfur concentrations after the third SESR cycle. Sulfur was detected in the spent catalyst and sorbent materials, with a higher proportion in the sorbent for the highest H2S concentration tested (1000 ppm). H2 yield decreased by 10.8% and 4.5% points for biogas H2S concentrations of 500 and 1000 ppm after five cycles, respectively, while H2 purity decreased by only 3 vol.% and 2 vol.% points, respectively.

Effects of hydrogen sulfide on the growth and physiological characteristics of Miscanthus sacchariflorus seedlings under cadmium stress

As a gas signal molecule, hydrogen sulfide (H2S) can participate in many physiological and biochemical processes such as seed germination and photosynthesis regulation. In order to explore the regulatory effect of H2S on the growth of Miscanthus sacchariflorus under Cd stress and to provide sufficient theoretical basis for the complex action of H2S and energy plants to remediate soil pollution. In this experiment, the effects of different concentrations of H2S (10, 25, 50, 100, 300, 400, 500 μmol·L−1 (μM)) pretreatment on the growth index, lipid peroxidation degree, chlorophyll (Chl) content, osmoregulation substance content, antioxidant enzyme activity and non-enzymatic antioxidant content of M. sacchariflorus under Cd stress (50 μM) were studied. The results showed that under Cd stress, the reactive oxygen species (ROS) content in the body of M. sacchariflorus was unbalanced, and the growth were severely inhibited, the activities of antioxidant enzymes, such as catalase (CAT) and superoxide dismutase (SOD) significantly decreased, and the content of osmoregulation substance, ascorbic acid (AsA) and glutathione (GSH) significantly increased. With the increase of H2S concentration, its effect on resisting Cd stress can be shown as "low concentration promotes, high concentration inhibits". When the concentration of H2S ≤ 300 μM, although there was no significant difference in Cd content compared with Cd treatment alone, it can regulate the activities of peroxidase (POD), SOD, glutathione reductase (GR) and monodehydroascorbate reductase (MDHAR), increase the content of osmoregulation substances, oxidized glutathione (GSSG), and the transformation rate of AsA and dehydroascorbic acid (DHA) to reduce the oxidative damage and improve the growth and photosynthetic indicators of plants; when the concentration of H2S ≥ 400 μM, Cd content in the ground and root decreased significantly, but the transport factor increased significantly, the growth status of M. sacchariflorus were more severely inhibited by the combined stress of H2S and Cd. In this experiment, it was found that the concentration of H2S pretreatment ≤ 300 μM could regulate the growth of M. sacchariflorus under Cd stress to normal level, and when the treatment concentration was 50 μM, the effect was the best. It will provide a new idea for the treatment of contaminated soil by energy plants.

Modelling the effect of pH and H2S on the germination of F. graminearum spores under different temperature conditions

Fusarium graminearum (F. graminearum) is a vital pathogen of Fusarium head blight (FHB). Hydrogen sulfide (H2S), which can be induced by stress in plants as a fungal inhibitor, affects the germination of spores through the detection of environmental factors such as temperature and pH. Based on mathematical models, F. graminearum was treated with different temperatures, pH, and H2S concentration to investigate spore germination events. This paper considered the synergistic effects of temperature and pH on spores in order to determine the optimal germination environment. Under these circumstances, the inhibition of spore germination with different concentrations of H2S was quantified. The results suggested that the germination time negatively correlates with the germinating rate. An increase in temperature altered the weak alkali preference of F. graminearum spores. At 28 °C, spores were more sensitive to the changes in pH. H2S gas could delay the germinating process significantly, however the required H2S concentration varied with environmental changes. This paper provides a perspective on the synergistic effect of temperature and pH on spore germination and contributes to determining the concentration of H2S as a management of FHB.

H2S Alleviates Propofol-Induced Impaired Learning and Memory by Promoting Nuclear Translocation of Nrf2 and Inhibiting Apoptosis and Pyroptosis in Hippocampal Neurons.

Repeated exposure to propofol can affect their learning and memory functions, but the mechanism remains unclear. The current study aimed to investigate the mechanism underlying the effect of hydrogen sulfide (H2S) on the alleviation of propofol-induced learning and memory impairment, mediated by promoting nuclear translocation of the nuclear factor erythroid 2-related factor 2 (Nrf2) and inhibiting apoptosis and pyroptosis in hippocampal neurons. Rats used in this study were successively exposed to 200 mg/kg propofol for 8 consecutive weeks, followed by inhalation of 10, 40 or 80 ppm H2S. Subsequently, the effects of different concentrations of H2S on learning and memory were assessed using the water maze assay. Additionally, the effects of H2S on cell apoptosis and pyroptosis and nuclear translocation of Nrf2 in hippocampal neurons were also determined. Furthermore, NaHS (200 μmol/L) was used as an in vitro donor for H2S, and rescue experiments were carried out following Nrf2 knockdown in H19-7 cells. Moreover, Nrf2 function was inhibited following treatment with an intraperitoneal injection of ML385 (30 mg/kg) in the rats. The effects of H2S on reactive oxygen species (ROS) generation, cell apoptosis, and pyroptosis in propofol-treated and Nrf2-deficient H19-7 cells were also investigated. Exposure to propofol for 8 weeks affected the ability of the rats to find underwater platforms (p < 0.01). Further, the exposure induced cell apoptosis and NLR family pyrin domain containing 3 (NLRP3)-related pyroptosis (p < 0.01). Although inhalation of 10 ppm H2S did not attenuate the aforementioned effects (p > 0.05), exposure to 40 and 80 ppm H2S significantly alleviated propofol-induced injury in the hippocampal neurons (p < 0.01). However, the protective effect of 80 ppm H2S was more obvious as compared to that of the other two doses (p < 0.01). In addition, Nrf2 knockdown aggravated the propofol-induced cell pyroptosis and apoptosis as well as reversed the protective effect of H2S against these processes (p < 0.01). In vivo experiments in this study demonstrated that Nrf2 inhibition abrogated the protective effects of H2S inhalation against learning and memory impairment as well as propofol-induced cell apoptosis and pyroptosis in rats (p < 0.01). H2S could attenuate propofol-induced damage in hippocampal neurons by promoting the nuclear translocation of Nrf2 and inhibiting cell apoptosis and pyroptosis.

Assessment of sulfide corrosion cracking and hydrogen permeation behavior of ultrafine grain high strength steel

In this work, the hydrogen permeation behavior and sulfide corrosion cracking susceptibility of ultrafine grain high strength steel were studied under different concentrations of H2S and pH. The critical sulfide stress cracking factor (KISSC) displays an exponential decrease with trapped hydrogen concentration in the steel. High content of retained austenite and dislocations contribute to high trap density of atomic hydrogen within the ultrafine grain high strength steel. Austenite absorbed more hydrogen as potential cracking sites while bainite with large grain size helps to maintain sulfide corrosion cracking resistance.

Protective Effect of Hydrogen Sulfide on Cerebral Ischemia-Reperfusion Injury.

The brain is the most sensitive organ to hypoxia in the human body. Hypoxia in the brain will lead to damage to local brain tissue. When the blood supply of ischemic brain tissue is restored, the damage will worsen, that is, cerebral ischemia-reperfusion injury. Hydrogen sulfide (H2S) is a gaseous signal molecule and a novel endogenous neuroregulator. Indeed, different concentrations of H2S have different effects on neurons. Low concentration of H2S can play an important protective role in cerebral ischemia-reperfusion injury by inducing anti-oxidative stress injury, inhibition of inflammatory response, inhibition of cell apoptosis, reduction of cerebrovascular endothelial cell injury, regulation of autophagy, and other ways, which provides a new idea for clinical diagnosis and treatment of related diseases. This review aims to report the recent research progress on the dual effect of H2S on brain tissue during cerebral ischemia/reperfusion injury.

Mechanism of improving the stability of activated carbon catalyst by trace H2S impurities in natural gas for hydrogen production from methane decomposition

Direct methane decomposition for hydrogen production is considered a clean technology with limited CO2 emission. However, catalysts usually suffer from deactivation due to carbon deposition. This study reported a method of improving the catalyst stability by using a trace amount of H2S which naturally exists in natural gas, and the action mechanism of H2S was discussed. Coconut shell activated carbon (AC) was used as the catalyst, the pure methane was mixed with 100, 200, and 300 ppm H2S and decomposed at high temperature. Results show that adding different concentrations of H2S can increase the methane conversion and delay the deactivation time of the AC catalyst. Through scanning electron microscopy characterization and Brunauer-Emmet-Teller analysis, it was found that the positive effect of H2S is achieved by changing the carbon deposition morphology which in turn changes the AC pore width distribution and the specific surface area. Under the action of H2S, AC has a relatively large number of micropores during the reaction, promoting the adsorption of methane molecules on AC. First-principles calculations show that H2S changes the reaction pathway of methane dehydrogenation and promotes methane decomposition.

Sulfurous thermal waters stimulate the osteogenic differentiation of human mesenchymal stromal cells – An in vitro study

Strategies aimed at delaying the onset of bone tissue degeneration and the resulting skeletal fragility are key to decrease the risk of bone fracture correlated to ageing. The therapeutic properties of sulfurous thermal waters (STWs), rich in hydrogen sulfide (H2S), have been claimed for centuries. However, the direct regulation of bone cells by STWs has not been investigated yet. Here we aimed at analyzing the effect of STWs on cultured human mesenchymal stromal cells (hMSCs) derived from bone tissue. Two concentrations of STWs from 2 health spa centers in Italy (here named STW-1 and STW-2) containing, respectively, high and moderate quantities of H2S, were added to the culture media. Cytotoxicity and osteogenic differentiation were evaluated. We provided first evidence that treatment of hMSCs with STWs results in a sharp increase in intracellular H2S content, coherent with the different concentrations of H2S, thereby reveling that STWs-released H2S is internalized by cells. STWs treatment significantly induced osteogenic differentiation of hMSCs. In particular, mineral apposition was increased with a similar pattern by the two STWs, while mRNA expression of osteogenic markers (BSP, OC, RUNX-2, OPN) was differently affected. Only STW-2 induced a significant, dose-dependent increase in these gene expression. These findings support the rationale for the use of STWs as a complementary treatment of bone wasting diseases.

Hydrogen sulfide attenuates diabetic neuropathic pain through NO/cGMP/PKG pathway and μ-opioid receptor.

There are currently approximately 425 million diabetic patients worldwide, of which approximately 90% of patients with diabetes suffer from neuropathy. Diabetic neuropathic pain (DNP) is a common complication of diabetic neuropathy. Nearly half of the patients hospitalized with diabetes have pain symptoms or symptoms related to neurological injury, and the incidence increases with age and diabetic duration. Anti-DNP analgesics have either limited therapeutic effects or serious side effects or lack of clinical trials, which has limited their application. Physiopathological mechanisms and treatment of DNP remain a significant challenge. The present confirmed that inhalation of H2S may attenuate the diabetic neuropathic pain through NO/cGMP/PKG pathway and μ-opioid receptor. It provides us the animal study foundation for the application of H2S on the treatment of DNP and clarifies some target molecules in the pain modulation of DNP.

Assessment of hydrogen embrittlement severity of an API 5LX80 steel in H2S environments by integrated methodologies

High strength steel, as API 5L grade X80 and above, have been applied in pipelines for sour service in oil and gas industry. Hence, comes the concern about the risks comprising hydrogen diffusion and embrittlement due to combined effect of operational conditions and corrosive environment containing hydrogen sulphide (H2S). Many efforts have been made to predict and understand the mechanisms involving hydrogen embrittlement under applied strain, nonetheless they are still not entirely understood. Furthermore, the growth of iron sulphide scales can influence on the diffusion process. This study investigates the behaviour of the API X80 steel concerning hydrogen absorption in solutions with different concentrations of H2S, by integrating different test methodologies at static and tensile conditions. It aims to evaluate hydrogen embrittlement susceptibility of the steel by means of hydrogen permeation and slow strain rate tests and a new complementary image processing methodology. Particularly, the embrittlement phenomenon is studied alongside with iron sulphide film influence as a protective barrier to hydrogen entry in sodium thiosulphate brines containing up to 10 ppm of H2S. Investigations by means of electrochemical impedance spectroscopy and surface analysis indicated that exists a relationship between different concentrations of H2S, scale precipitation and its barrier protectiveness to hydrogen uptake. It was observed a diminution of hydrogen permeation through the steel due to formation of mackinawite, however under tensile stress the film breakage may allow not only hydrogen diffusion into the steel, but also the occurrence of hydrogen embrittlement.

Effects of Mo2C loading and H2S concentration on Mo2C/Al2O3 catalyst applied in sulfur‐resistant methanation

Mo2C/Al2O3 catalyst was prepared by the impregnation method with urotropine and ammonium paramolybdate. The catalytic effect of Mo2C as a typical transition‐metal carbide in sulfur‐resistant methanation was studied. The catalysts prepared were characterized by N2 adsorption–desorption, X‐ray diffraction, transmission electron microscopy, H2‐temperature‐programmed reduction, and Raman spectra, with the results confirming the formation of β‐molybdenum carbide on the surface of the catalysts. Studies on catalysts with different loading doses indicate that the optimal loading of Mo2C/Al2O3 is about 15 wt.%, which enables CO conversion rate of up to 47%, with methane selectivity of up to 53%. This work further explored the effect of different concentrations of H2S in the raw gas on the performance of the catalyst, with the results showing that high concentration of H2S (&gt;1500 ppm) can lead to sulfuration of active species on the catalyst, while resulting in a decrease in the catalytic activity.

A dual-function fluorescent probe for discriminative detection of hydrogen sulfide and hydrazine

A dual-function fluorescent probe (Probe 1) was developed for discriminative detection of hydrogen sulfide (H2S) and hydrazine (N2H4). The 2,4-dinitrophenyl moiety was reactive with H2S and the α,β-unsaturated ketone was reactive with N2H4. The discriminative detection of H2S and N2H4 was achieved via the colour change of a solution or test strip of Probe 1-H2S and Probe 1-N2H4. The test strips of Probe 1 reacted with different concentrations of H2S to produce colour changes from colourless to dull red under natural light, and reacted with different concentrations of N2H4 to produce color changes from purple to purplish blue under 254 nm ultraviolet light. Therefore, Probe 1 could be used as a sensor to detect N2H4 and H2S.

Ultrafast Response/Recovery and High Selectivity of the H2S Gas Sensor Based on α-Fe2O3 Nano-Ellipsoids from One-Step Hydrothermal Synthesis.

Ultrafast response/recovery and high selectivity of gas sensors are critical for real-time and online monitoring of hazardous gases. In this work, α-Fe2O3 nano-ellipsoids were synthesized using a facile one-step hydrothermal method and investigated as highly sensitive H2S-sensing materials. The nano-ellipsoids have an average long-axis diameter of 275 nm and an average short-axis diameter of 125 nm. H2S gas sensors fabricated using the α-Fe2O3 nano-ellipsoids showed excellent H2S-sensing performance at an optimum working temperature of 260 °C. The response and recovery times were 0.8 s/2.2 s for H2S gas with a concentration of 50 ppm, which are much faster than those of H2S gas sensors reported in the literature. The α-Fe2O3 nano-ellipsoid-based sensors also showed high selectivity to H2S compared to other commonly investigated gases including NH3, CO, NO2, H2, CH2Cl2, and ethanol. In addition, the sensors exhibited high-response values to different concentrations of H2S with a detection limit as low as 100 ppb, as well as excellent repeatability and long-term stability.

A Visible Colorimetric Fluorescent Probe for Hydrogen Sulfide Detection in Wine.

A new efficient and practical fluorescent probe 6-(benzo[d]thiazol-2-yl)naphthalen-2-yl-thiophene-2-carboxylate (probe 1) was synthesized to detect hydrogen sulfide (H2S). The addition of H2S caused the solution of probe 1 to change from colorless to yellow, and the solution of probe 1 changes to different colors with respect to different concentrations of H2S. Importantly, probe 1 could help detect H2S efficiently by a distinct color response as a visible detection agent. Probe 1 reacted with various concentrations of H2S (0–200 μM), and the detection limit for H2S was 0.10 μM. Particularly, probe 1 can be applied as a sensor to detect H2S accurately in wine samples.

Effect of hydrogen sulfide(H2S) fumigation on quality of passionfruit (Passiflora edulis sims)

In order to investgate the effects of H2S on the quality of cold-storage passion fruit, fresh harvested fruits were treated with different concentrations of H2S(0 mmol/L, 1 mmol/L, 2 mmol/L, 3 mmol/L), packaged with BOPP plastic wrap and placed into 5±1°C for 35 days. Samples were randomly selected and at 7-days interval during cold storage, compared the preservation effect of different concentrations of H2S. The results indicated that the fruits with 2 mmol/LH2S treatment have better chroma and lower weight loss rate, and soluble solid content, titratable acidity, vitamin C, sugar were preserved at higher level than that of control fruits during storage time. These results showed that 2 mmol/LH2S treatment could maintain the quality of passion fruit during cold storage.

Pitting Corrosion of Supermartensitic Stainless Steel in Chloride Solutions Containing Thiosulfate or H2S

Deepwater oil and gas extraction environment have high salinity, low oxygen content, and the presence of carbon dioxide and hydrogen sulfide (H2S). Handling of H2S-containing gaseous mixtures should be carried out in laboratories with special installations, owing to the high toxicity of this gas. An alternative is the use of non-toxic substances that can generate H2S in the medium, such as sodium thiosulfate. The objective of this work is to study the viability of substituting H2S by thiosulfate for the evaluation of the susceptibility to pitting corrosion in sour environments of the supermartensitic stainless steel (SMSS). The electrochemical behavior of SMSS in NACE TM0177-2016 solution C solution containing different concentrations of H2S or thiosulfate ions at 10−3 mol/L was performed by using cyclic potentiodynamic polarization (CPP). The condition of shorter OCP time (300 s) prevents the formation of a passive layer and allows the generation of H2S due to the reaction of the solution with the metal surface. The CPP curves of SMSS in the media containing 3% H2S/Ar (2.96 kPa) and 10−3 M of thiosulfate ions (OCP 300 s) were similar, the pitting potential was about − 322.5 ± 8.7 and − 338.8 ± 11.4 mVAg/AgCl, respectively, and the pit morphology showed several small pits on the steel surface in both conditions, suggesting the viability of the use of thiosulfate-containing brines to simulate H2S solutions.

The roles of plasticity and evolutionary change in shaping gene expression variation in natural populations of extremophile fish.

The notorious plasticity of gene expression responses and the complexity of environmental gradients complicate the identification of adaptive differences in gene regulation among populations. We combined transcriptome analyses in nature with common-garden and exposure experiments to establish cause-effect relationships between the presence of a physiochemical stressor and expression differences, as well as to test how evolutionary change and plasticity interact to shape gene expression variation in natural systems. We studied two evolutionarily independent population pairs of an extremophile fish (Poecilia mexicana) living in toxic, hydrogen sulphide (H2 S)-rich springs and adjacent nontoxic habitats and assessed genomewide expression patterns of wild-caught and common-garden-raised individuals exposed to different concentrations of H2 S. We found that 7.7% of genes that were differentially expressed between sulphidic and nonsulphidic ecotypes remained differentially expressed in the laboratory, indicating that sources of selection other than H2 S-or plastic responses to other environmental factors-contribute substantially to gene expression patterns observed in the wild. Concordantly differentially expressed genes in the wild and the laboratory were primarily associated with H2 S detoxification, sulphur processing and metabolic physiology. While shared, ancestral plasticity played a minor role in shaping gene expression variation observed in nature, we documented evidence for evolved population differences in the constitutive expression as well as the H2 S inducibility of candidate genes. Mechanisms underlying gene expression variation also varied substantially across the two ecotype pairs. These results provide a springboard for studying evolutionary modifications of gene regulatory mechanisms that underlie expression variation in locally adapted populations.