Papers by Keyword: Hydrogen Sulfide

Abstract: Hydrogen sulfide (H₂S) isclassified as toxic gases that are commonly known to be generated from an anaerobic process, volcanic explosion and petroleum related processes. Low concentration of H₂S causes irritation on human eyes and respiratory system as well as nuisance problem due to its rotten-egg smell. Insanitary dumpsite of municipal wastes containing high organic fraction could be a source of H₂S emission, which affects the quality of life of nearby communities. This study assessed the H₂S dispersion from dumpsite in Nakhon Si Thammarat using the source dispersion model, AERMOD. Emission rate of H₂S generated at dumpsite was estimated using emission factor of 1.76 mg.m^-2.d^-1 taken from AP-42 (USEPA.). For meteorological data, hourly average data in 2012 were collected from three meteorological stations which were Nakhon Si Thammarat, Surat Thani and Trang Provinces. Meteorological data were primarily utilized from Nakhon Si Thammarat. Only missing values were filled by the data from Surat Thani and Trang, respectively. Results revealed that maximum concentrations of H₂S in 2012 were 0.595, 0.066 and 0.058 ppb, respectively for 1 hour average (1^st highest), 24 hour average (1^st highest) and annual average over the study area of 10 km x 10 km surrounding the source. Maximum concentration of H₂S emitted from dumpsite was mainly confined within 1.5 km surrounding the sources, particularly to the east and northeast area. The simulated concentrations of H₂S did not exceed the suggested standard values; however, the 1^st highest hourly average concentration was reached the odor threshold (0.5 ppb). To clarify the simulated H₂S concentrations, further works should be included the field sampling of H₂S at dumpsite to obtain the actual emission rate. Meteorological data in several years should be also used to provide the concrete pattern of H₂S dispersion.

Abstract: To better regulate (up and down) the activation of SRB thereby contributing to EOR, efficiency of growth and inhibition of SRB was studied in this paper.Six different growth media were tested in total.The optimal growth media were selected based on growth rate and variations of pH between the start and end point of growth. Of the six media, complex I was selected as the best medium in which SRB grew to stationary-phase in less than 8 days with the highest cells’ concentration. Finally, the effects of NO₃^- on growth and persistence of SRB were studied by using abroad range concentrations of NO₃^-. The result indicated that SRB growth could be significantly inhibited at NO₃^- of 80 mM.

Abstract: Manganese dioxide loaded active carbon absorbents (MnO₂/AC) were prepared. Mixture of H₂S and N₂ is used to evaluate the performance of absorbents in fixed adsorption bed for H₂S removal. A suitable H₂S removal activity was obtained with adsorbent of manganese dioxide to active carbon ratio of 1:1, drying temperature of 120°C, drying time of 24 h. The breakthrough time of 70 min with total gas volume of 1400 mL, adsorption temperature of 40°Cwere observed. Comparing with the unmodified active carbon, its breakthrough H₂S capacity increased by 96.9 mg·g^-1.

Abstract: Objective To establish and verify analytical methods of hydrogen sulfide (H₂S) detection in heart blood by Chemical Method and Gas Chromatography - Mass Spectrometry (GC/MS). Method Take 3-5mL of heart blood, placed in 20mL vial, adding 3-5mL of deionized water, 1mL of 2mol/L hydrochloric acid (HCl), stamped seal, and denatured at 60 °C water bath for 30min. Both Chemical Method and GC/MS were used to assay the headspace inside vial. Results These two methods are all detected H₂S in the heart blood of the poisoning death. Conclusion These two methods are rapid, simple, reliable, and of high sensitivity, reproducibility, and suitable for rapid analysis of hydrogen sulfide in forensic and criminal casework.

Abstract: In this paper, an efficient metal oxide sorbents for the deep removal of H₂S were synthesized using equal volume impregnation (EVIM) method. Modified coconut shell charcoal was selected as support to deposite the particles of copper oxide onto the surface. And copper nitrate were selected as the active component precursors in the preparation process of sorbents. Sorption experiments were carried out at room temperature in fixed-bed reactor. The grain size and crystal form of loading metals were characterized by X-ray diffraction (XRD). We investigated the effects of modifier onto coconut shell charcoal, load rate of metal oxide and calcination temperature on the desulfurization activity of the sorbent. Results show that the best modifier for coconut shell charcoal is KOH, which is significantly better than the other modifiers. And the optimum load rate is 20%(wt), the optimum calcination temperature is 300°C. Copper oxide onto the surface of modified coconut shell charcoal proved to be monoclinic nanoparticles with grain size of 18.7nm. Sulfidation test was carried out on the condition of i) the concentration of hydrogen sulfide gas (mixed with nitrogen ) is 1024.2ppm and ii) gas velocity is 20ml/min, iii) 0.1g sample in the middle of the fixed-bed reactor (length: 450 mm, interior diameter: 5 mm) to test. The sample show excellent sulfur removal efficiency and its breakthrough time is up to 287 min on this condition.

Abstract: Sewage Scaling in the process of sewage transfer in gas field containing hydrogen sulfide is one of the major problems in the gas field production. So to study the scaling mechanism of sewage containing hydrogen sulfide is necessary and can provide thought for antiscale of transfer pipelines. The study shows that as a result of the corrosion effect of hydrogen sulfide, it makes increases of roughness in the pipe inner surface and increases of small particles in the sewage, promotes crystallization of the scale crystal, and changes the structure and size of the scale crystal. The slow oxidation of hydrogen sulfide produces elemental sulfur particles, promotes the crystallization of more scale crystals, and increases the amount of scale formation. The changes of pH value in the sewage change the concentration of hydrogen sulfide ions in sewage containing hydrogen sulfide, change the sewage corrosion, and thus change the composition of sewage scaling. Under the condition of containing hydrogen sulfide, sewage presents the characteristic of corrosion first and scaling later,then corrosion promotes the scaling, and the scale contains more corrosion products.

Abstract: In this paper, nanocopper oxide is prepared by complexing-precipitate, and the influence of different process parameters on the removal of H₂S performance are studied, and make a comparison for two other methods. The results indicate that different complexing agent, the molar ratio of Cu²⁺/OH^- and calcination temperature, etc., effect the desulfurization activity of nanocopper oxide. nanocopper prepared under optimum conditions (the complexing agent is ammonia, the molar ratio of Cu²⁺/OH^- is 1:3.0, calcination temperature is 400 °C) exhibits best desulfurization activity with a H₂S breakthrough time of 235 min, this is much longer than that prepared by hydrothermal method and sol-gel method with breakthrough time of H₂S only 20 min and 50 min, respectively; XRD analysis shows that the big grain size of nanocopper oxide and low purity are not in favor of H₂S adsorption at room temperature.

Abstract: With the development of urbanization, the odor from municipal wastewater treatment plants has disturbed the neighborhood and the control of odor has become an urgency research subject. The H₂S odor was treated by the biofilter. The removal load of the biofilter, end products of H₂S degradation, and operation process were studied in this paper. The results of removal H₂S odor with the biofilter were as follows: When the gas flow rate was 1000m³/h (resident time 16.2s) and 1250m³/h (resident time 13.0s), and the inlet concentration of H₂S ranged from 1.876 to 34.705mg/m³, the removal rate maintained above 99.92%, and the average outlet concentration was 0.001 mg/m³ which was far lower than the national level of discharge standard. The relationship between removal rate and temperature satisfied with the formula , and for H₂S, θ=1.016. Furthermore, the end products of H₂S degradation were only sulfate without sulfide. With the increase of sulfate, the removal of H₂S was not affected. The study of operating parameters with the biofilter provided the necessary technical support for industrial design and operation control.

Abstract: A rapid removal method of hydrogen sulfide (H2S) gas is studied in the present paper at ambient conditions. These capture agents are powers of grain sizes and convenient for injection on H2S gas at the site of accident. The agents are characterized by SEM and N2 adsorption-desorption method, etc. The test on capturing H2S was experimented and the result indicated that the prepared agents can reduce the H2S concentration in the air to a harmless level rapidly.

Abstract: A dynamic model of mass transfer was developed with mass transfer equation and mass transfer differential equation according to two film theory for the simultaneous transport of hydrogen sulfide through hollow fiber membrane (HFM) contactors while using N-methyldiethanolamine (MDEA) as the chemical solvent. The model results are in excellent agreement with the experimental data. The results indicate that the removal of H2S increased while increasing concentration of MDEA and gas pressure, however, the removal of H2S decreases while increasing gas velocity. The concentration of H2S increases at the same place in the lumen while increasing gas velocity. There is serious decreasing amplitude of axial concentration of H2S during the initial stage, but it slows down at half of the length and a great reduction of H2S concentration in radial direction with the increase of the length. The decreasing amplitude is dropped due to the concentration of H2S decreased in radial direction. The model can indicate H2S removal rate in given operational conditions and offer theory evidence for the design of membrane contactor. Natural gas is believed to play a vital role in the next few decades for industrial and domestic utilization. It is considered as one of the cleanest and safest of all energy sources. However, nature gas is not a pure hydrocarbon and sometimes it has some sour gases such as hydrogen sulfide which has high toxicity. Hydrogen sulfide can not only corrode equipment and transmission pipeline under aerobic and hot humid conditions but also cause catalyst poisoning, even serious threaten the safety of human. Wet desulphurization is widely used for natural gas treatment and aqueous solutions of alkanolamines are often used as absorption solvent. Among these alkanolamines, MDEA as an absorption solvent of acid gases is widely used today because it possesses the characteristics such as higher H2S selectivity, bigger absorption capacity, lower regeneration energy, smaller hot-degradation and lower circulating load. But desulphurization unit can be seriously corroded in the sulfur removal process. On the other hand, these conventional processes such as absorption towers, packed and plate columns possess many disadvantages such as flooding, foam formation, and demand high capital and operating costs. So the technology meets a certain obstacles. Recently, new processes using gas–liquid membrane contactors as gas absorption devices have been a subject of great interest. Among the diversity of membrane geometries available for membrane contactors, hollow-fiber membrane contactors are favored due to their high surface/volume ratio for separation which is 30-50 times compared with traditional absorbers. This type of process offers several practical advantages including low energy and operating costs, simplicity and occupying small area. In addition, membrane contactors as unit equipment can be combined according to actual need. [4~5] used polypropylene hollow fiber membrane as the absorber and MDEA as the chemical solvent for the absorption of H2S via changing operating conditions (e.g. temperature, pressure, the concentration of the solvent, flux of gas-liquid phase) and studied the influence of the changes to mass transfer coefficient and sulfur removal efficiency. The results indicate that the sulfur removal efficiency can be 95% above by optimizing the operating conditions. At home and abroad, comprehensive two-dimensional mathematical models were developed based on differential equation. Wang [6] simulated the absorption of CO2 using different absorption medium in hollow fiber membrane contactors. But they did not consider the effect of mixed gas. Chen [7] modeled the distribution of reactants and products concentration in the shell side in different typ es of reaction. However, the model can not obtain the concentration of H2S in the lumen. Rami Faiz [8] modeled the distribution of acid gas, but the mathematical model was not validated by the experimental work.