Trace Amounts Of Hydrogen Sulfide Research Articles

The Influence of Hydrogen Sulfide on the Optical Properties of Planetary Organic Hazes: Implications for Exoplanet Climate Modeling

Planetary organic hazes can play a significant role in influencing a planet’s radiative balance and climate, with their impact determined by the optical properties of the haze. The optical properties, in turn, are partly influenced by particle composition. Our previous work, Reed et al., demonstrated that trace amounts of hydrogen sulfide (H2S) in haze chemistry can substantially affect the haze’s composition by generating organosulfur compounds and increasing the amount of organic haze produced. However, no study has measured the optical properties of an H2S-influenced organic haze. Here we present results from laboratory experiments measuring the real (scattering, n) and imaginary (absorbing, k) refractive indices of haze analogs produced from photochemistry of gas mixtures composed of 0.1% CH4 and variable H2S (0–10 ppmv) in N2. The optical properties of the aerosol produced were measured in real-time using coupled photoacoustic and cavity ring-down spectroscopy with 405 and 532 nm wavelengths of light. Our findings show that the total extinction of light (scattering plus absorption) by the aerosol increases as a function of H2S mixing ratio. We provide our best-fit equations for predicting n and k at 405 and 532 nm as a function of the sulfur to carbon molar ratio (S:C) of the precursor gas mixture. Further, we demonstrate how these changes in optical properties could alter the transmittance of 405 and 532 nm light through a haze layer. These results have potential implications for modeling the climate, habitability, and spectra for exoplanets exhibiting organic haze.

Biogas reforming to syngas in a DBD plasma reactor with dielectric materials packing: Effect of H2S on the conversion of CH4 and CO2

Biogas is a renewable energy produced due to the anaerobic decomposition of plants and animals. Biogas contains a high amount of methane (CH4), carbon dioxide (CO2), and trace amounts of hydrogen sulfide (H2S). It is naturally released in the environment, and the composition varies depending on the source it is generated. The primary focus of the study is to understand the influence of H2S on CH4 and CO2 conversion during syngas production. The effect of applied voltage on biogas reforming reaction with different dielectric materials (glass beads, γ-Al2O3, ZrO2, and quartz wool) packed in a discharge zone was investigated by using a dielectric barrier discharge (DBD) non-thermal plasma reactor. The influence of gas composition and packed bed on the efficiency of the biogas reforming reaction was investigated. After that, the biogas reforming reaction with packed dielectric material was performed without H2S and subsequently with H2S (blended with N2) while keeping the residence time constant. It was observed that H2S has a significant effect on the conversion. The CH4 conversion drastically dropped from 23% (without H2S) to 9% (with H2S), and CO2 conversion dropped from 18% to 11 % at 22 kV with quartz wool packed DBD. Energy efficiency decreased from 3.12 mmol/kJ (without H2S) to 1.78 mmol/kJ (with H2S) with glass beads packed DBD. Moreover, H2S has more effect on CH4 conversion than CO2.

Carbon-Dioxide and Hydrogen-Sulfide Removal from Simulated Landfill Gas Using Steel Slag

Municipal solid waste landfills are a source of major greenhouse gases such as methane (CH4) and carbon dioxide (CO2) and emit a trace amount of hydrogen sulfide (H2S). Recently, steel slag has extensively been used for mineral CO2 sequestration to minimize the CO2 releases to the atmosphere. This study explores the potential of basic oxygen furnace (BOF) steel slag to simultaneously remove CO2 and H2S from landfill gas (LFG). Various batch and column tests were conducted to evaluate the CO2 and H2S removal potential of the BOF slag under various conditions such as moisture content and particle size of the BOF slag. The three different particle sizes of BOF slag (coarse, as-is, and fine) were exposed to continuous flow of a synthetic LFG [50% CO2, 48.25% CH4, and 1.75% H2S by volume (v/v)] in a column reactor to evaluate the effect of particle size on CO2 and H2S removal capacity of the slag. Similarly, the BOF slag was exposed to synthetic LFG as well as 20% (v/v) of H2S alone in batch reactors at varying moisture contents (10%–30% by weight) to evaluate the effect of moisture content on the CO2 and H2S removal capacity of the slag. A significant H2S removal of 27 g H2S kg−1 BOF slag and CO2 removal of 76 g CO2 kg−1 BOF slag were obtained in the batch reactor. The fine BOF slag (<0.106 mm) showed the maximum CO2 removal (300 g CO2 kg−1 BOF slag) and H2S removal (38 g H2S kg−1 BOF slag) upon exposure to continuous synthetic LFG flow in the column reactor. The quantitative X-ray diffraction (QXRD) analysis showed the highest increase in carbon (77.5 g C kg−1 BOF slag) and sulfur (28 g S kg−1 BOF slag) contents in the fine BOF slag, which was consistent with the mass balance of carbon and sulfur from CO2 and H2S uptake in column tests. The major reaction product with H2S was elemental sulfur depicted by the significant increase in the sulfur content in the X-ray fluorescence analysis. The key minerals involved in carbonation reactions were lime, portlandite, and larnite, as these minerals showed significant reduction in weight percentage (100%, 82%, and 80%, respectively) in the QXRD analysis. Overall, BOF slag showed promising results in mitigating CO2 and H2S from LFG.

Hydrogen sulfide removal from biogas in biotrickling filter system inoculated with Paracoccus pantotrophus

Biogas generated from anaerobic digestion can be employed as fuel in either industrial boilers or electric generators. The presence of a trace amount of hydrogen sulfide (H2S) in the biogas can severely impact on the biogas applications. Biotrickling filter (BF) inoculated with a pure strain of sulfide oxidizing bacterium, Paracoccus pantotrophus NTV02 was used to remove H2S from the biogas in the present work. P. pantotrophus was successfully immobilized on plastic packing media in BF after 228 h inoculation. H2S containing biogas and liquid media was subsequently fed into BF under countercurrent direction with fixed inlet gas flowrate and liquid media recirculation rate at 0.5 LPM (120 s EBRT) and 3.6 L/h. H2S in the biogas was varied in the range of 100–2,000 ppmv. BF achieved H2S removal efficiency at 98.3–99.7% at its inlet concentration ranges of 300–1,500 ppmv of H2S. The removal efficiency (99.5%) little declined as H2S inlet reached 2,000 ppmv. The maximum of elimination capacity was 82.98 g H2S/m3·h at the loading rate of 83.58 g H2S/m3·h.

TSR, deep oil cracking and exploration potential in the Hetianhe gas field, Tarim Basin, China

Oil and gas in deep and ultra-deep strata has been a hot topic in both research and exploration. The understanding of reservoirs in relatively shallow strata may be of significance for deep exploration. The Hetianhe gas field is the only large gas field discovered yet in the southwest region of the Tarim Basin, with a small quantity of condensate oil penetrated and a burial depth ranging from 1035 m to 2885 m, and the origin and source of the oil and gas has long been unclear. By using comprehensive 2D gas chromatography/time of flight mass spectrometry (GC × GC-TOFMS), abundant diamondoids and some thiadiamondoids were detected in condensate oil samples collected from 3 wells, additionally, the features, including dry gas with a trace amount of hydrogen sulfide, heavy carbon isotopes, and similar sulfur isotopes in hydrogen sulfide and Cambrian gypsum, indicate that the oil and gas has undergone the thermochemical sulfate reduction (TSR) and thermal cracking. The current reservoir temperature, from 35 °C to 83 °C, does not meet the condition for the onset of these secondary geochemical alterations, therefore, the oil and gas may originate from deep strata. According to the reconstruction of the geologic evolution, deep oil and gas may have migrated vertically along faults and accumulated in the Hetianhe structure formed after 10 Ma to form the secondary gas reservoirs; hence it is inferred that favorable petroleum plays may exist in deep strata. The thick evaporite in the Middle Cambrian and the high-quality dolomite reservoirs in the Lower Cambrian constitute a favorable reservoir-seal assemblage, with the current depth between 8500 m and 10000 m and reservoir temperature above 200 °C, where the TSR and thermal cracking may occur. The sulfur isotope of hydrogen sulfide also demonstrates the occurrence of TSR process in the Cambrian strata. Therefore, large-scale of oil and gas reserves may be preserved in the stable zones in the Cambrian sub-salt strata, and it is suggested to strengthen hydrocarbon exploration in the Cambrian sub-salt strata in the southwest region of the Tarim Basin.

Poisoning of Ni-Based anode for proton conducting SOFC by H2S, CO2, and H2O as fuel contaminants

It is well known that conventional solid oxide fuel cells (SOFCs) based on oxide ion conducting electrolyte (e.g., yttria-stabilized zirconia, YSZ) and nickel (Ni) - ceramic cermet anodes are susceptible to poisoning by trace amount of hydrogen sulfide (H2S) while not significantly impacted by the presence of carbon dioxide (CO2) and moisture (H2O) in the fuel stream unless under extreme operating conditions. In comparison, the impacts of H2S, CO2, and H2O on proton-conducting SOFCs remain largely unexplored. This study aims at revealing the poisoning behaviors caused by H2S, CO2, and H2O for proton-conducting SOFCs. Anode-supported proton-conducting SOFCs with BaZe0.1Ce0.7Y0.1Yb0.1O3 (BZCYYb) electrolyte and Ni-BZCYYb anode and La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) cathode as well as Ni-BZCYYb/BZCYYb/Ni-BZCYYb anode symmetrical cells were subjected to low ppm-level H2S or low percentage-level CO2 or H2O in the hydrogen fuel, and the responses in cell electrochemical behaviors were recorded. The results suggest that, contrary to conventional SOFCs that show sulfur poisoning and CO2 and H2O tolerance, such proton-conducting SOFCs with Ni-BZCYYb cermet anode seem to be poisoned by all three types of "contaminants". Beyond that, the implications of the experimental observations on understanding the fundamental mechanism of anode hydrogen electrochemical oxidation reaction in proton conducting SOFCs are also discussed.

Assessment of Sulfur Poisoning of Ni/CGO-Based SOFC Anodes

The presence of fuel impurities, such as hydrogen sulfide, siloxane and phosphine, in biogas, diesel and natural gas can cause Solid Oxide Fuel Cell (SOFC) degradation due to surface poisoning of Ni-containing anodes. In this regard, Ni/CGO anodes have shown higher sulfur tolerance than Ni/YSZ anodes and a comparable high performance. In order to allow for a more profound understanding of the processes underlying sulfur poisoning, this study presents an extensive experimental investigation of commercial Ni/CGO-based SOFC operating on H2/H2O fuel gases and reformate fuel mixtures with trace amounts of hydrogen sulfide (H2S). The short-term poisoning behavior of high-performance electrolyte-supported Ni/CGO10-based cells was systematically investigated by means of transient voltage stability experiments and electrochemical impedance measurements for a wide range of operating conditions. The effects of temperature (800 – 950 °C) and current density (OCV – 0.75 A·cm‒2) on the extent of sulfur poisoning (1 – 20 ppm H2S) was evaluated. The poisoning behavior was shown to be completely reversible for short exposure times in all cases. The chemical capacitance of Ni/CGO10 anodes was demonstrated to be strongly dependent upon temperature and gas phase composition reflecting a changing Ce3+/Ce4+ ratio in the CGO phase. Using a model reformate as fuel gas, it was shown that CO can still be electrochemically converted under sulfur exposure. Furthermore, long-term experiments of 1500 h were conducted at 900 °C and 0.5 A·cm‒2 with and without sulfur exposure and the degradation progress was monitored by impedance spectroscopy.

Assessment of Sulfur Poisoning of Ni/CGO-Based SOFC Anodes

The presence of fuel impurities, such as sulfur, siloxane and phosphorus, in biogas, diesel and natural gas can cause Solid Oxide Fuel Cell (SOFC) degradation due to surface poisoning of Ni-containing anodes. In this regard, Ni/CGO anodes were shown to display higher sulfur tolerance than Ni/YSZ anodes and a comparable high performance. In order to allow for a more profound understanding of the processes underlying sulfur poisoning, this study presents an extensive experimental investigation of commercial Ni/CGO-based SOFC operating on H2/H2O gas and reformate fuel mixtures with trace amounts of hydrogen sulfide (H2S). The short-term poisoning behavior of high-performance electrolyte-supported Ni/CGO10-based cells was systematically investigated by means of transient voltage stability experiments and electrochemical impedance measurements for a wide range of operating conditions. The effects of temperature (800 – 950 °C) and current density (OCV – 0.75 A·cm‒2) on the extent of sulfur poisoning (1 – 20 ppm H2S) was evaluated. The poisoning behavior was shown to be completely reversible for short exposure times in all cases. By means of equivalent circuit modeling, the chemical capacitance of Ni/CGO10 anodes was demonstrated to be strongly dependent on temperature and gas phase composition reflecting a changing Ce3+/Ce4+ ratio in the CGO phase. Using a model reformate as fuel gas, it was shown that CO can still be electrochemically converted under sulfur exposure. Furthermore, long-term experiments of 1000 h were conducted at 900 °C and 0.5 A·cm‒2 with and without sulfur exposure and the degradation progress was monitored by impedance spectroscopy. Moreover, comprehensive post-mortem analysis including FIB/SEM, TEM and XRF was carried out in order to identify the nature and location of the occurring microstructural changes.

Techno-Economic Feasibility of Selective CO2 Capture Processes from Biogas Streams Using Ionic Liquids as Physical Absorbents

Biogas from anaerobic digestion of sewage sludge is a renewable resource with high energy content, which is composed mainly of CH4 (40–75 vol %) and CO2 (15–60 vol %). Other components, such as water (H2O, 5–10 vol %) and trace amounts of hydrogen sulfide and siloxanes, can also be present. A CH4-rich stream can be produced by removing the CO2 and other impurities so that the upgraded biomethane can be injected into the natural gas grid or used as a vehicle fuel. The main objective of this paper is to assess the technical and economic performance of biogas upgrading processes using ionic liquids that physically absorb CO2. The simulation methodology is based on the COSMO-SAC model as implemented in Aspen Plus. Three different ionic liquids, namely, 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, 1-hexyl-3-methylimidazoliumbis[(trifluoromethyl)sulfonyl]imide, and trihexyl(tetradecyl)phosphonium bis[(trifluoromethyl)sulfonyl]imide, are considered for CO2 capture in a pressure-swing regenera...

Poisoning of Proton Conducting SOFC By Hydrogen Sulfide and Carbon Dioxide Fuel Contaminants

It is well known that conventional solid oxide fuel cells (SOFCs) with oxygen ion conducting electrolyte and nickel (Ni) anode are susceptible to poisoning by trace amount of hydrogen sulfide (H2S) while not significantly impacted by presence of carbon dioxide (CO2) in the fuel stream. In comparison, the impacts of H2S and CO2 as fuel contaminants on proton-conducting SOFCs remain unexplored. Here we report our study aimed at revealing the poisoning behavior caused by H2S and CO2 for proton-conducting SOFCs. Anode-supported proton-conducting SOFCs with BaZe0.1Ce0.7Y0.1Yb0.1O3 (BZCYYb) electrolyte and Ni-BZCYYb anode and La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) cathode were subject to ppm-level H2S or percentage-level CO2 as fuel contaminants in hydrogen fuel. The response in cell electrochemical behavior and the change in materials microstructure and composition are characterized. Preliminary results suggest that, contrary to conventional SOFCs that show “sulfur poisoning” and “CO2 tolerance”, such Ni-BZCYYb anode/BZCYYb electrolyte/LSCF cathode proton-conducting SOFC button cells show good tolerance to H2S up to ~5 ppmv while severe poisoning by CO2 at even low percentage level. Experimental results aimed at understanding such different electrochemical behaviors for proton-conducting SOFCs versus conventional oxygen ion conducting SOFCs will be presented and their implications on the fundamental mechanism for anode hydrogen electrochemical oxidation reaction in proton conducting SOFCs will be discussed.

Conventional hydrothermal synthesis of nanoporous molecular sieve 13X for selective adsorption of trace amount of hydrogen sulfide from mixture with propane

Nanoporous molecular sieve 13X was successfully synthesized through the conventional hydrothermal method by using sodium aluminates as Al source and water-glass solution as an economic reagent for Si source. The hydrothermal reaction was performed under a static condition in an air oven maintained at 90 ± 5 °C for 24 h. Nano molecular sieve was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and nitrogen adsorption desorption tests. The adsorption capacity of molecular sieve 13X for trace amount of hydrogen sulfide (72 ppm) mixed with propane was investigated using the volumetric method by two different detectors. After adsorption process the amount of H2S in output gas was about 27 ppm and this confirms approximately more than 62% adsorption at 25 bar and 298 K. As compare CO2 adsorption capacity was measured by the same method. The high adsorption capacity of CO2 is attributed to the high micropore volume on 13X sample. Therefore a cost-effective adsorbent was synthesized successfully to separate the small amounts of acidic and corrosive gas (H2S) from propane.

Lifetime and Performance Prediction of SOFC Anodes Operated with Trace Amounts of Hydrogen Sulfide

Chemical degradation of Solid Oxide Fuel Cell (SOFC) anodes can be caused by various types of impurities present in practical fuels, as e.g. sulfur, chlorine, phosphorus and siloxane. To allow for a deeper understanding of the processes leading to sulfur poisoning, this study presents a modeling work of SOFC operating on H2/H2O and CH4/H2/H2O gas mixtures with different hydrogen sulfide (H2S) concentrations. In order to interpret experimental measurements, an elementary kinetic model is developed comprising a detailed multi‐step reaction mechanism of sulfur formation and oxidation at Ni/YSZ anodes coupled with channel gas-flow, porous-media transport and elementary charge-transfer chemistry. A thermodynamic and kinetic data set of sulfur formation and oxidation is derived based upon various literature sources including a coverage-dependent description of the enthalpy of surface-adsorbed sulfur. Firstly, the developed model is validated against literature-based sulfur chemisorption isobars, and subsequently against electrochemical button-cell experiments displaying a significant influence of operation temperature and applied potential on cell performance and degradation. It is shown that sulfur surface coverage increases with increasing current density indicating a low sulfur oxidation rate. In order to gain for an advanced fundamental understanding of sulfur poisoning, sensitivity analyses towards total anode resistance and sulfur coverage for different operating conditions will be presented. Furthermore, the identified elementary sulfur poisoning reactions are used to extend an existing reaction mechanism for methane steam reforming which is then validated based upon a variety of electrochemical experiments. It is shown that atomically adsorbed sulfur significantly influences heterogeneous reforming chemistry, causing a substantial decrease in OCV. Under polarization, at constant current densities the cell voltage decreases in a non-linear way. After the removal of hydrogen sulfide from the feed gas the cell shows a faster recovery than in H2/H2O mixtures. In addition, numerical impedance simulations over a wide range of operating conditions were performed, which allows a physically-based assignment of observed gas concentration, heterogeneous chemistry and electrochemical processes.

Lifetime and Performance Prediction of SOFC Anodes Operated with Trace Amounts of Hydrogen Sulfide

An elementary kinetic model is developed to predict the influence of sulfur on Ni/YSZ anodes of solid oxide fuel cells (SOFC) performance. A multi-step reaction mechanism describing the formation and oxidation of sulfur on the Ni surface is coupled with gas transport in the channel and porous phase, and charge-transfer processes. A thermodynamic and kinetic data set of sulfur formation and oxidation is derived based upon various literature sources including a coverage-dependent description of the enthalpy of surface-adsorbed sulfur. The validity of the model is demonstrated on two SOFC operation modes, namely H2/H2O/H2S and CH4/H2/H2O/H2S fuel mixtures, at different operating conditions using various electrochemical literature experiments. The first concern is the influence of adsorbed sulfur on charge-transfer processes and the second concern is the effect of adsorbed sulfur on complex methane reforming chemistry. The results reveal that sulfur surface coverage increases with current density demonstrating a low sulfur oxidation rate.

Elementary Kinetic Numerical Simulation of Ni/YSZ SOFC Anode Performance Considering Sulfur Poisoning

An elementary kinetic model is developed and applied to explore the influence of sulfur poisoning on the behavior of solid oxide fuel cell (SOFC) anodes. A detailed multi-step reaction mechanism of sulfur formation and oxidation at Ni/YSZ anodes together with channel gas-flow, porous-media transport and elementary charge-transfer chemistry is established for SOFCs operating on H2/H2O mixtures with trace amounts of hydrogen sulfide (H2S). A thermodynamic and kinetic data set is compiled from various literature sources. The derived chemical model, validated against sulfur chemisorption isobars taken from literature, is used to analyze performance drops of SOFCs working under typical fuel cell operating conditions. Electrochemical results show that at relatively low H2S concentrations SOFC button-cell performance can be interpreted using chemical sulfur formation. However, when the concentration is sufficiently high, the inclusion of second stage degradation and triple-phase boundary reconstruction is necessary to describe the performance decrease. Additionally, it is shown that the sulfur surface coverage increases with increasing current density. In order to shed more light on advanced fundamental understanding of cell poisoning, sensitive analyses toward total anode resistance and sulfur coverage for different operating conditions were performed.

Study on the Corrosion Behavior of Two Kinds of Tubing at Different Temperatures

Aimed at the problem of sulfur-resistant corrosion in environment with carbon dioxide(CO2)and trace amounts of hydrogen sulfide (H2S), Tafel polarization curves and electrochemical impedance spectroscopy techniques were employed to study the electrochemistry corrosion behavior of two kinds of 80S(A and B) at different temperatures. The methods of weight-loss，scanning electron microscope and X-ray diffraction (XRD) analysis were used to study on the corrosion behavior of the sulfur-resistant tubes, including electrochemical impedance spectroscopy , average corrosion rates and the corrosion morphologies. The results showed that the corrosion potential and corrosion rates (CR) of two samples were different with the changing of the test temperatures. With the increase of the temperature, the corrosion potential decreased, and the corrosion rates increased, but decreased at 120°C. The corrosion-resistant of A80S was slightly superior to the B80S. The serious pitting corrosion and the maximum average CR occurred at 90°C. The XRD analysis suggested that the main corrosion products were FeS.

Influence of cell voltage and current on sulfur poisoning behavior of solid oxide fuel cells

The sulfur poisoning behavior of nickel-yttria stabilized zirconia (YSZ) cermet anodes in solid oxide fuel cells (SOFCs) was investigated under both potentiostatic and galvanostatic conditions. While the observed relative drop in cell power output caused by sulfur poisoning decreases as the cell-terminal voltage is lowered potentiostatically (thus more current passing through the cell), it increases as more current is drawn from the cell galvanostatically (thus leading to lower terminal voltage). The apparent contradictory trends in relative performance loss due to sulfur poisoning are explained using a simple equivalent circuit analysis, which was further validated by impedance measurements of cells before and after poisoning by trace amounts of hydrogen sulfide (H 2S) under different conditions. Results suggest that the relative increase in cell internal resistance caused by sulfur poisoning is smaller when more current is drawn from the cell (or the cell-terminal voltage is lowered) under either potentiostatic or galvanostatic conditions. Thus, the increase in anode polarization resistance, not the drop in cell power output, should be used to describe the degree of sulfur poisoning in order to avoid any confusion.

Determination of trace amounts of hydrogen sulfide in a gas flow using a piezoelectric detector

The following parameters are substantiated and optimized in the detection of H2S in a gas flow: the nature and flow rate of the carrier gas; the qualitative and quantitative composition of a sensing coating; the technique of its application onto the electrodes of a piezoelectric detector; and the geometrical parameters (volume and configuration) of a flow detecting cell. A testing unit for detecting H2S in the range from 3 to 18 mg/m3 is developed on the basis of a modified piezoelectric resonator with high frequency characteristics (13–16 MHz).

Measurement of low concentration and nano-quantity hydrogen sulfide in aqueous solution: measurement mechanisms and limitations

To measure hydrogen sulfide (H2S) level in biological samples in vivo on a real-time basis with high resolution is greatly needed for advancing our understanding of the biological role of H2S. Traditional H2S measurements usually need large tissue samples and complex procedures. However, H2S concentration is very low in human bodies and the tissue sample is limited for medical treatment purposes. There is a need to develop a new paradigm for the real-time measurement of a trace amount of hydrogen sulfide with a small amount of tissue samples or in vivo. We previously reported a method to measure low concentration H2S solution using carbon nanotubes and the fluorescence spectra of Raman and confocal laser scanning microscopes. We obtained that the measurement resolution with a confocal laser scanning microscope is higher than that with a Raman microscope; in particular, 10 µM concentration difference can be detected with a confocal laser scanning microscope. In this paper, we present the underlying mechanism and limitation of this method together with other traditional methods based on the theoretical analysis, which leads to the finding of further research on the measurement of low concentration and nano-quantity H2S solution.

Biological removal of carbon disulfide from waste air streams

AbstractA pilot‐scale biological control system for the treatment of 3400 m3 h−1 of a gaseous stream containing up to 7.8g CS2 m−3 and trace amounts of hydrogen sulfide (H2S) was installed in a cellulose sponge manufacturing facility. The objective was to demonstrate the capability of the process to attain sustained re m oval efficiencies of 90% for CS2 and 99% for H2S. The system consisted of two sequential biotrickling reactors, which had been previously inoculated with an adapted microbial consortium. During the pilot test, stable removal efficiency and elimination capacity of +90% and 220g CS2 m−3 h−1, respectively, we re attained with an empty bed residence time (EBRT) of 33 seconds for a period of several weeks. Efficiencies greater than 99% we re always obtained for H2S. Based on the results, the system was determined to be an effective process to remediate waste air streams containing reduced sulfur compounds generated at cellulose sponge facilities.

A Simple Spectrophotometric Method for the Determination of Hydrogen Sulfide Based on Schiff's Reaction

A simple and sensitive spectrophotometric method for the determination of trace amounts of hydrogen sulfide after fixation in a zinc acetate trapping solution is described. The fixed sulfide was made to react with formaldehyde to form a hydrosulfide adduct which reacts with pararosaniline in an acid medium to form a colored product. The product was stabilized with gelatin and thiocyanate for the absorbance measurement at 520 nm with a Beer's law range of 0–20 μg hydrogen sulfide. The relative standard deviation for ten determinations at 10 μg H 2S is 2.4%. The effect of various interfering gases was overcome by the use of a simple collection procedure. The method was applied to the determination of residual amounts of H 2S present in a laboratory fume hood and the results were compared with those of the standard methylene blue method.