Increase In H2S Concentration Research Articles

Corrosion behavior of SMSS 13Cr and SS 316L under chloride solution and H2S/CO2 environments

Abstract Corrosion resistant alloys (CRAs) include a range of different stainless steels and nickel alloys that are used in corrosion-aggressive environments encountered in oil and gas operations. Supermartensitic stainless steel (SMSS 13Cr) has been used in the manufacture of steel tubes for use in oil drilling due a more financially viable option to replace the austenitic stainless steel (SS 316L) in the oil and gas market. This present work estimate the effect of the hydrogen sulphide (H2S) on SMSS 13Cr and SS 316L, in saline solution, simulating the operating conditions in the oil and gas industry. Corrosion behavior was monitored using Potentiodynamic-Potentiostatic-Potentiodynamic (PD-PS-PD) technique in order to obtain pitting potential (Ep) or crevice potential (Ecrev)) and repassivation potential (Erp) while the long-term Open Circuit Potential (OCP) technique was applied to estimate the stable corrosion potential (Ecorr*). A Scanning Electron Microscope (SEM) equipped with Energy Dispersive X-ray Spectroscopy (EDS) and Optical Microscopy were used for surface characterization. With all analysis carried out was possible to propose a trend regarding the pitting probability. The pitting increases with increasing H2S concentration on SSSM 13Cr, consequently, large, and deeper pits were observed, making possible to develop into cracks if there are mechanical stresses. On the contrary, the pitting probability for the SS 316L is low (compared with SMSS 13Cr) for all environments reproduced here in this research.

Air quality in a revitalized special economic zone at the center of an urban monocentric agglomeration

In this study, we have examined the air quality within a revitalized, post-industrial urban area in Łódź, Poland. The use of Dron technology with mobile measurement equipment allowed for accurate assessment of air quality (particulate matter and gaseous pollutants) and factors influencing air quality (wind speed and direction) on a local scale in an area of 0.18 km2 and altitudes from 2 to 50 m. The results show that the revitalization carried out in the Lodz special economic zone area contributed to eliminate internal air pollution emitters through the use of ecological and effective heat sources. The exceedances permissible concentration values were local, and concerned mainly the higher measurement zones of the troposphere (more than 30 m above ground level). In the case of gaseous pollutants, higher wind speeds were associated with a decrease in the concentration of SO2 and an increase in H2S concentration. In both cases, the wind contributed to the occurrence of local areas of accumulation of these gaseous pollutants in the spaces between buildings or wooded areas.

The CBS/H2S signalling pathway regulated by the carbon repressor CreA promotes cellulose utilization in Ganoderma lucidum

Cellulose is an important abundant renewable resource on Earth, and the microbial cellulose utilization mechanism has attracted extensive attention. Recently, some signalling molecules have been found to regulate cellulose utilization and the discovery of underlying signals has recently attracted extensive attention. In this paper, we found that the hydrogen sulfide (H2S) concentration under cellulose culture condition increased to approximately 2.3-fold compared with that under glucose culture condition in Ganoderma lucidum. Further evidence shown that cellulase activities of G. lucidum were improved by 18.2-27.6% through increasing H2S concentration. Then, we observed that the carbon repressor CreA inhibited H2S biosynthesis in G. lucidum by binding to the promoter of cbs, a key gene for H2S biosynthesis, at “CTGGGG”. In our study, we reported for the first time that H2S increased the cellulose utilization in G. lucidum, and analyzed the mechanism of H2S biosynthesis induced by cellulose. This study not only enriches the understanding of the microbial cellulose utilization mechanism but also provides a reference for the analysis of the physiological function of H2S signals.

Effects of differential speed rolling and H2S poison on hydrogen storage performance of ZK60 alloys ball-milled with C, Pd, Ag, and Zr

The commercial ZK60 magnesium alloy was used to investigate hydrogen absorption performance. The ZK60 alloy was severely deformed via differential speed rolling with differential speeds of 6:3 and 9:3. High energy ball milling was used to blend deformed ZK60 powder with 5 wt% activated carbon(C), 0.5 wt% silver (Ag), 0.5 wt%palladium (Pd), and 1 wt% zirconium (Zr) for 20h at 1725 rpm. Hydrogen absorption characteristics at different low temperatures and number of cycles were analyzed using Sievert's apparatus with hydrogen supplied with H2S impurities. The microstructure of the powder was analyzed field emission scanning electron microscope (FESEM). The hydrogen absorption capacity increases with the temperature rise, and maximum capacity(6.02 wt%) was observed in 5C1Zr deformed at 9:3DSR at 200 °C after five cycles. Hydrogen absorption capacity increases after each hydrogenation cycle in 5C0.5Ag and 5C1Zr but remains the same in 5C0.5Pd. The increase in H2S concentration decreases the hydrogen capacity, and increase in the number of cycles further deteriorates absorption capacity when the differential speed ratio is 6:3. The H2S concentration variation has almost no effect at the differential speed of 9:3. The maximum hydrogen absorption kinetics (74.7%) in 10min was observed in 5C1Zr. A more refined dendritic microstructure was observed in ZK60 alloy deformed with a differential speed ratio of 9:3.

Hydrothermally synthesized MXene Ti3C2/Zn2SnO4 based nanocomposite for H2S sensing at room temperature

Hydrogen sulfide (H2S) gas sensors with high response and minimum limit of detection at room temperature are of great importance to ensure the safety of humans and the environment. A series of samples such as MXene Ti3C2, Ti3AlC2, WS2, MoSe2/Zn2SnO4 and spherical Zn2SnO4 nanoparticles were synthesized via hydrothermal method in this paper. Different characterizations were performed on these samples to check crystal structures, morphologies, chemical states, etc. And gas sensing properties were also performed and analyzed deeply. A series of sensor sheets were fabricated via the spin coating method based on synthesized samples for gas sensing properties. MXene Ti3C2/Zn2SnO4-5 based gas sensor detected the highest response (110) towards 8 ppm H2S with excellent selectivity, the minimum limit of detection (0.01 ppm), mediate long-term stability and good reproducibility compared with other fabricated sensors at room temperature. Also, the sensor response was increased with the increase of H2S concentration. Experimental results showed that the highest response of Ti3C2/Zn2SnO4-5 based gas sensor was accredited to heterojunction, higher BET surface area, and increased oxygen species. The simple way synthesized nanocomposite and fabricated sensors throw a novel idea for tracing H2S at the lowest concentration to prevent different diseases.

Central sleep apnea and exposure to ambient hydrogen sulfide emissions from massive strandings of decomposing sargassum in the Caribbean

BackgroundSargassum invasion of Caribbean and American shorelines is a recurring environmental hazard. Potential health effects of long-term chronic exposure to sargassum gaseous emissions, notably hydrogen sulfide (H2S), are overlooked. H2S plays an important role in neurotransmission and is involved in generating and transmitting respiratory rhythm. Central sleep apnea (CSA) has been attributed to the depression of respiratory centers. ObjectiveEvaluate the effects of exposure to sargassum-H2S on CSA. MethodsThis study, set in the Caribbean, describes the clinical and polysomnographic characteristics of individuals living and/or working in areas impacted by sargassum strandings, in comparison with non-exposed subjects. Environmental exposure was estimated by the closest ground H2S sensor. Multivariate linear regression was applied to analyze CSA changes according to cumulative H2S exposure over time. Effects of air pollution and other sargassum toxic compounds (NH3) on CSA were also controlled. ResultsAmong the 685 study patients, 27 % were living and/or working in sargassum impacted areas. Compared with non-exposed patients, exposed ones had similar sleep apnea syndrome risk factors, but had increased levels of CSA events (expressed as absolute number or % of total sleep apnea). Multivariate regression retained only male gender and mean H2S concentration over a 6-month exposure period as independent predictors of an increase in CSA events. A minimal exposure length of 1 month generated a significant rise in CSA events, with the latter increasing proportionally with a cumulative increase in H2S concentration over time. ConclusionThis pioneer work highlights a potential effect of sargassum-H2S on the central nervous system, notably on the modulation of the activity of the brain's respiratory control center. These observations, jointly with previous studies from our group, constitute a body of evidence strongly supporting a deleterious effect of sargassum-H2S on the health of individuals chronically exposed to low to moderate concentration levels over time.

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.

Impact of gas composition and reservoir heterogeneity on miscible sour gas flooding — A simulation study

Proper handling of the produced sour gas is a big challenge for operating companies due to the serious environmental and technical problems caused by H2S and CO2. The reinjection of the produced sour gas into oil reservoirs is an environmentally friendly as well as an economically attractive method due to the low investment cost and incremental oil recovery. However, the sour gas injection for enhanced oil recovery (EOR) is a relatively new approach with numerous uncovered perspectives, especially in a heterogeneous reservoir. The objective of this study is to investigate the effect of gas composition and reservoir heterogeneity on the miscible displacement of reservoir oil using sour gas.The reservoir oil consisting of 15 mol% H2S and 4 mol% CO2 from an oilfield in the North Caspian region was used. First, the phase behavior alteration of reservoir oil due to the injection of various gases, namely H2S, CO2, CH4, acid, and sour gas was analyzed. Then, the effect of gas type on minimum miscibility pressure (MMP) was investigated based on a semi-analytical tie-line method. Moreover, 2D and 3D numerical simulations were conducted to understand the oil recovery performance of various gas injection options and the effect of permeability heterogeneity on sour gas flooding efficiency. The findings showed that higher H2S content in the injected gas narrows the two-phase envelope and decreases the bubble point pressure. Moreover, it was observed that MMP decreases with increasing H2S concentration, which provides a favorable condition for achieving miscibility. Additionally, an increase in H2S concentration in sour gas improves its oil recovery efficiency by extending gas breakthrough time and elongating the plateau period of oil rate. These results are useful for designing, optimizing, and implementing sour gas injection for EOR in oil reservoirs that have access to sour gas sources.

Effect of Hydrogen Sulfide on Essential Functions of Polymorphonuclear Leukocytes.

Impaired polymorphonuclear leukocyte (PMNL) functions contribute to increased infections and cardiovascular diseases in chronic kidney disease (CKD). Uremic toxins reduce hydrogen sulfide (H2S) levels and the anti-oxidant and anti-inflammatory effects of H2S. Its biosynthesis occurs as a side process of transsulfuration and in the disposal of adenosylhomocysteine, a transmethylation inhibitor and proposed uremic toxin. PMNL chemotaxis was measured by the under-agarose method, phagocytosis, and oxidative burst by flow cytometry in whole blood and apoptosis by determining DNA content by flow cytometry and morphological features by fluorescence microscopy. Sodium hydrogen sulfide (NaHS), diallyl trisulphide (DATS) and diallyl disulphide (DADS), cysteine, and GYY4137 were used as H2S-producing substances. Increased H2S concentrations did not affect chemotaxis and phagocytosis. NaHS primed PMNL oxidative burst activated by phorbol 12-myristate 13-acetate (PMA) or E. coli. Both DATS and cysteine significantly decreased E. coli-activated oxidative burst but had no effect on PMA stimulation. While NaHS, DADS, and cysteine attenuated PMNL apoptosis, GYY4137 decreased their viability. Experiments with signal transduction inhibitors suggest that the intrinsic apoptosis pathway is mainly involved in GYY4137-induced PMNL apoptosis and that GYY4137 and cysteine target signaling downstream of phosphoinositide 3-kinase.

Copper-multiwalled carbon nanotubes decorated fiber-optic surface plasmon resonance sensor for detection of trace hydrogen sulfide gas

A fiber-optic surface plasmon resonance (SPR) hydrogen sulfide (H2S) gas sensor is proposed and fabricated by using silver/triaminopropyltriethoxysilane/copper-multiwalled carbon nanotubes (Ag/APTES/Cu-MWCNT) as sensing film. A single-mode fiber (SMF) is spliced between two multimode fibers (MMF) to form an MMF-SMF-MMF sensing structure. The Ag/APTES/Cu-MWCNT sensing film is coated on the surface of SMF. The performance and stability of the sensor were investigated in detail. With the increase of H2S concentration in the range of 10–100 ppm, the redshift of the resonance dip reaches 126.465 nm, and the logarithm of H2S concentration and the resonance dip wavelength shift satisfy the linear relationship. In the range of 1–10 ppm, the wavelength shifts 117.421 nm, and H2S concentration and the dip wavelength shift meet a linear relationship. The sensitivity (12.9849 nm/ppm) is obtained, the detection limit (0.146 ± 0.031 ppm) is determined, and the response time is about 28 s. The sensor has excellent selectivity, good time, humidity and temperature stability, which has potential application in the field of trace H2S gas monitoring.

Prediction of H2S corrosion depth for water-cooled wall in lower furnace of utility boiler

The presence of H2S near the water-cooled wall of utility boiler can lead to accelerated corrosion wastage on the furnace wall. While the existing evaluation of annual corrosion wastage caused by H2S is not suitable for the boiler that operated in a wide load range. In this study, a novel H2S corrosion model is developed to predict the metal wastage of water-cooled walls in the lower furnace. Three key independent variables including metal temperature, H2S concentration and corrosion time are considered simultaneously. Based on the experimental corrosion data of pure Fe and boiler steel SA213-T2, the prediction model is represented by a mathematical equation derived from the regression analysis. The validation of this equation is conducted by comparing the predicted and lab-scale corrosion depths, and a reasonable agreement is obtained. The single-factor analyses indicate that the corrosion depth of SA213-T2 almost increases linearly with the increase of H2S concentration, and the growth rate of corrosion depth could raise as the metal temperature increases. Under the extreme condition that temperature as 773 K and H2S as 800 ppm, the predicted annual corrosion depth of SA213-T2 is 1129 μm. In practical terms, the annual corrosion wastage should be calculated by summing the sub-wastages formed during different periods of a year. The predictive model proposed in this study could play an indispensable role in the sub-wastage calculation and benefit the estimation of the annual corrosion wastage.

An integrated geological, engineering and geochemical approach for screening of H2S increasing mechanism in Shanul gas field coastal Fars Provinance, Zagros Basin, Iran

This study reports a comprehensive approach for analysis of increasing hydrogen sulfide (H2S) concentration after 10 years of sweet gas production from Kangan and Dalan formations (Khuff) in a gas field. Increasing H2S concentration as a toxic and corrosive component in gas phase will affect the project economics and needs immediate action in terms of production/surface processing facilities and also prediction of future gas contamination. Thus, a comprehensive study was conducted to determine the possible mechanisms behind increasing H2S concentration in some wells. Geological, engineering and field data were analyzed and all possible contributing parameters were studied in an integrated approach. All possible reasons including producing formations, water level movement, cumulative gas production, individual well gas rate, water composition/production, well completion (flow behind casing, leakage, etc.), faults, regional production, etc. were examined. Migration from a deeper gas formation was concluded to be the source of local increase in H2S concentration. To confirm the hypothesis, sampling of gas from 10 wells were performed and a geochemical survey was conducted based on sulfur isotope. Results showed a relation between increasing concentration of H2S and sulfur isotope values. Heavier values of sulfur isotope were obtained for those wells showing most increase in H2S concentration. In addition, sulfur isotope of contaminated wells were in agreement of that for deeper anhydrite formation. Results of geochemical analysis confirmed gas migration from deeper formation which was proposed by geological/engineering survey.

The influence of H2S on hydrogen absorption and sulfide stress cracking resistance of high strength low alloy carbon steel C110

The application of high strength low alloy carbon steel C110 in wet-H2S environment is limited by sulfide stress cracking (SSC). The objective of this research is to evaluate the effect of the environmental H2S content on the susceptibility to SSC. Since SSC is hydrogen induced fracture, the study focusses on: (1) evaluating the effect of H2S concentration on hydrogen absorption, (2) assessing SSC susceptibility by a novel slow strain rate tensile testing (n-NTSSRT) method under both sour and non-sour environments, (3) the correlation between absorbed hydrogen concentration and SSC susceptibility. The results show that with increasing H2S concentration, sub-surface hydrogen concentration C0 increases exponentially, while critical stress intensity factor KISSC decreases. The application of n-NTSSRT methodology criteria is determined to be 1 mol% H2S, which corresponding to a C0 value of 6.66 × 10−6 mol/cm3. When H2S concentration is higher than 1 mol%, the KISSC values should be calculated by assuming the fracture is linear elastic fracture. Otherwise, the elastoplastic fracture solution J-integral should be considered.

Stirring-based control strategy for microaerobic H2S removal in sequencing batch anaerobic digesters

Microaeration in fermenters is challenging due to the rapid increase of H2S concentration upon the start of stirring, which makes biogas utilization less attractive. On these occasions, apparent H2S production exceeds the ability of sulfur-oxidizing bacteria (SOB) to remove H2S, which results in peak H2S concentrations in biogas. This study shows that such peaks can be reduced by stirring optimization. For the first time, the effect of the stirring intensity on microaeration was evaluated in a lab-scale sequencing batch reactor and supported by a biokinetic mathematical model. Single stirring intensity (15, 25, 35, and 55 RPM) and gradually increasing stirring intensity (15 to 35 RPM) were compared. Despite achieving a stably low concentration of H2S in the fermenter at low stirring speed, the accumulation of volatile fatty acids in liquid occurred. However, with gradually increasing stirring intensity, slower stirring at the beginning of the cycle led to the slower release of H2S, thereby, winning more time for SOB to remove H2S from biogas. H2S peaks were reduced by this strategy and no accumulation of volatile fatty acids in the liquid phase was observed. Since microaeration is zero-waste chemical-free desulfurization method, its optimization and H2S peaks reduction can help to expand its use.

Reservoir gas isotope fingerprinting and mechanism for increased H2S: An example from Middle East Shanul gas field

Hydrogen sulfide (H2S) is an undesirable compound in oil and gas reservoirs, which reduces the economic value of gas reservoirs and has toxic and corrosive effects on reservoir operation equipment. Albeit initial generation mechanisms of hydrogen sulfide in gas reservoirs, increasing its concentration during the production phase may affect project economics. Thus, the determination of causes of increasing hydrogen sulfide concentration is of great importance. This study reports a systematic approach to investigate the possible mechanisms behind increasing H2S concentration in a carbonate gas reservoir after ten years of sweet gas production from an onshore field located in SW of Iran. Initial data during the development phase suggested a sweet gas reservoir fluid and all production and processing facilities were designed based on sweet gas production. Some wells showed increasing H2S concentration in two local sections of the field after ten years. Sampling from gas, water, and rock have been done, and isotope analysis was performed for both contaminated and non-contaminated wells. Geochemical and field data analysis were performed to determine the source of H2S increasing in this field. Results showed that the amount of sulfur isotope in the gas phase ranged from - 7.3 to −11.8‰. A general trend between the concentration of H2S and sulfur isotope was obtained. Sulfur isotope values of rock samples (core, drill cuttings, and outcrop samples), varied between + 8.3% and + 34.9% depending on formation age. Integration of geochemical, geological, and operational data indicated the occurrence and migration of H2S from an anhydrite rich formation at the bottom of the reservoir. All other possible mechanisms was rejected based on isotopic and geological evidence.

Study on fatigue crack growth rate of 15CrMo steel based on stress ratio and corrosion environment

In this paper, the fatigue crack growth rate of 15CrMo steel, a typical gas cylinder material, is studied under the condition of simulating the actual working condition of gas cylinder. The low-frequency corrosion fatigue tests with stress ratio of 0.1 and 0.5 are carried out in air and different concentrations of wet hydrogen sulfide environment. The relationships between da/dN and ΔK are expressed by Paris equation. The results show that the crack growth rate in hydrogen sulfide environment with concentration of 200 ppm is 27 times higher that in air. The addition of corrosion environment greatly fasts the crack growth rate of 15CrMo steel. With the increase of H2S concentration, the crack growth rate increases exponentially. With the increase of stress ratio, the average stress increases, the crack closure effect decreases, the crack tip is fully opened, and the contact area with corrosion medium increases, which results in the increase of crack growth rate.

In situ study of the electrochemical migration of tin in the presence of H2S

The electrochemical migration of tin in the presence of H2S was in situ investigated using optical and electrochemical techniques. The results show that dendrites co-exist with precipitates at H2S concentration range from 0 to 1000 ppmv; furthermore, the time to short circuit decreases with increasing H2S concentration. The essential reason is that higher H2S concentration increases the conductivity of electrolyte, resulting in a higher growth rate of dendrite. As the H2S concentration further increases up to 10,000 ppmv or 100,000 ppmv, no dendrites but precipitates can be observed. This can be attributed to that large amount of tin hydroxides and tin sulfides are produced quickly at the beginning of electrochemical migration test, which act as a barrier to hinder the arrival of Sn2+/Sn4+ to the cathode. Thus, no dendrites but precipitates can be found. Under square wave electric field with a time period of 1 s, it is observed that there are no dendrites but some precipitates. This is because there is a circulation between metal tin deposition during the first 0.5 s and its dissolution in the next 0.5 s. Therefore, the occurrence of short circuit in the presence of H2S is semi-cycle dependent.

Glutathione catabolism by Treponema denticola impacts its pathogenic potential

Treponema denticola is a spirochete that is etiologic for periodontal diseases. This bacterium is one of two periodontal pathogens that have been shown to have a complete three step enzymatic pathway (GTSP) that catabolizes glutathione to H2S. This pathway may contribute to the tissue pathology seen in periodontitis since diseased periodontal pockets have lower glutathione levels than healthy sites with a concomitant increase in H2S concentration. In order to be able to demonstrate that glutathione catabolism by the GTSP is critical for the pathogenic potential of T. denticola, allelic replacement mutagenesis was used to make a deletion mutant (Δggt) in the gene encoding the first enzyme in the GTSP. The mutant cannot produce H2S from glutathione since it lacks gamma-glutamyltransferase (GGT) activity. The hemolytic and hemoxidation activities of wild type T. denticola plus glutathione are reduced to background levels with the Δggt mutant and the mutant has lost the ability to grow aerobically when incubated with glutathione. The Δggt bacteria with glutathione cause less cell death in human gingival fibroblasts (hGFs) in vitro than do wild type T. denticola and the levels of hGF death correlate with the amounts of H2S produced. Importantly, the mutant spirochetes plus glutathione make significantly smaller lesions than wild type bacteria plus glutathione in a mouse back lesion model that assesses soft tissue destruction, a major symptom of periodontal diseases. Our results are the first to prove that T. denticola thiol-compound catabolism by its gamma-glutamyltransferase can play a significant role in the in the types of host tissue damage seen in periodontitis.

Simultaneous capture of NH3 and H2S using TiO2 and ZnO nanoparticles - laboratory evaluation and application in a livestock facility

Simultaneous removal of ammonia (NH3) and hydrogen sulphide (H2S) from pre-mixed gases and stored swine manure gases were investigated in laboratory and semi-pilot scale systems and in a swine production facility, using TiO2 and ZnO nanoparticles. Increase of NH3 concentration in the mixture from 50 to 500 ppmv led to higher breakthrough and equilibrium adsorption capacities, while increase of temperature had an opposite effect. Equilibrium adsorption capacities at 22 °C were in the range 6.92–11.95 mg NH3 g−1 and 1.35–3.57 mg NH3 g−1 at 280 °C. Increase of H2S concentration up to a certain level led to higher equilibrium adsorption capacities but no dependency between breakthrough adsorption capacity and H2S concentration was observed. Both breakthrough and equilibrium adsorption capacities increased with the increase of temperature. The highest equilibrium adsorption capacity of 52.31 mg H2S g−1 was obtained with 550 ppmv H2S in the mixture at 140 °C, while the lowest value was 14.55 mg H2S g−1 with 50 ppmv H2S at 22 °C. At low temperature (22 °C) NH3 adsorption occurred through both physical adsorption and chemisorption, while at 280 °C chemisorption was the dominant mechanism. A sulfidation reaction involving ZnO and H2S that was favored by higher temperatures was evident. Treating gases emitted from stored swine manure in a semi-pilot scale adsorption system led to complete elimination of NH3 and H2S. Application of a nano-based air filtration-circulation system with ZnO and TiO2 nanoparticles in a swine production room during manure handling led to removal efficiencies of 67–100% for H2S and 50–100% for NH3.

A dual-mode fluorescent probe for the separate detection of mercury(II) and hydrogen sulfide

A dual-mode fluorescent probe (Probe 1) was developed for the separate detection of Hg2+ and H2S. Probe 1 could detect Hg2+ and H2S through two different reaction sites, with the mechanism of Probe 1 for Hg2+ depending on the desulfurization reaction and for H2S depending on the nucleophilic addition reaction of an aldehyde with H2S. Separate detection of Hg2+ and H2S was achieved by determining the fluorescence emission wavelength of Probe 1-Hg2+ (443 nm, λab = 247 nm) and Probe 1-H2S (504 nm, λab = 256 nm). The fluorescence intensity of Probe 1 has a linear relationship with the concentration of Hg2+ in the range 0–7 μM and the LOD was 39.28 nM. And H2S in the range 0–110 μM, the LOD was 0.7449 μM. With increasing concentrations of Hg2+, test strips gradually became darker in color. The luminescence intensity of test strips gradually increased with increasing H2S concentration, and the initially colorless Probe 1 solution gradually changed to yellow under natural light with increasing H2S concentration. Probe 1 could be used for Hg2+ and H2S detection in real samples.