• Clean Technology
• /
• v.20 no.4
• /
• pp.367-374
• /
• 2014

Several experiments have been done to investigate the removal of hydrogen sulfide ($H_2S$) synthetic gas from biogas streams by means of chemical absorption and chemical reaction with 0.1-1 M Fe/EDTA solution. The roles of Fe/EDTA were studied to enhance the removal efficiency of hydrogen sulfide because of oxidizing by chelate. The motivation of this investigation is first to explore the feasibility of enhancing the toxic gas treatment in the biogas facility. The biogas purification strategy affords many advantages. For instance, the process can be performed under mild environmental conditions and at low temperature, and it removes hydrogen sulfide selectively. The end product of separation is elemental sulfur, which is a stable material that can be easily disposed with minor potential for further pollution. As the Fe-EDTA concentration increased, the conversion rate of hydrogen sulfide increased because of the high stability of Fe-EDTA complex. pH as an important environmental factor was 9.0 for the stability of chemical complex in the oxidation of hydrogen sulfide.

• Environmental Engineering Research
• /
• v.16 no.3
• /
• pp.159-164
• /
• 2011

This study examined the emission characteristics of impure gas-like hydrogen sulfide and siloxane contained in landfill gas (LFG) and investigated the effect of impure gas on LFG utility facilities. As a result of an LFG component analysis from eight landfills in the same environment, hydrogen sulfide averaged 436 ppmv (22-1,211 ppmv), and the concentration of total siloxane averaged 7.95 mg/$m^3$ (1.85-21.18 mg/$m^3$). In case of siloxane concentration by component, the ratio of D4 (average 3.79 mg/$m^3$) and D5 (average 2.64 mg/$m^3$) indicated the highest level. Different kinds of scales were found on the gas air heater (GAH) and inside the boiler. The major component of scale from the GAH was $Fe_2O_3$ of 38.5%, and it was caused by hydrogen sulfide. Other scale was found on the bottom and the wall of the boiler and the scale was silicon dioxide of 92.8% and 98.9%. The silicon dioxide scale was caused by combustion of siloxane. As a result of a scanning electron microscopy analysis, the structure of the silicon dioxide scale from the boiler was an immediate filamentous type. Consequently, as silicon dioxide scale is bulky, such bad effects were worsening, as an interruption in heat conduction, increase in fuel consumption, damage to the boiler by overheating, and clogged emission pipeline could occur in LFG utility facilities.

• Journal of the Korean Society of Safety
• /
• v.14 no.3
• /
• pp.127-133
• /
• 1999

One of the major malodorous gas at the working place is hydrogen sulfide and impregnated activated carbon fiber(ACF) was used as a adsorbent to remove this gas. ACF is treated and impregnated with chemicals to increase the adsorption capacity. The experiments showed that the adsorption efficiency for hydrogen sulfide was increased in case of impregnation with $Na_2CO_3$ or KI. Also, by the surface treatment with NaOH, the adsorption efficiency was increased however not so much as impregnation. KI was the best impregnant for this purpose and the optimum concentration was 9wt%. The adsorption capacity of hydrogen sulfide was more than 500mg/g ACF.

• Journal of Korean Society of Water and Wastewater
• /
• v.10 no.3
• /
• pp.83-91
• /
• 1996

The pulverized wastes originated from kitchen garbage grinder cause an additional load in sewage treatment plant and water environment. Therefore, several problems occur in sewer, such as microbial corrosion, odor, psychoda and fly interrupting flow of sewage etc. by their precipitation with earth and sand. This study was conducted on two experiments: hydrogen sulfide gas generation from sediments in sewer and anaerobic batch test. In anaerobic batch test, gas generation was increased when organic compounds were increased in concentration. Sulfide was decreased upon decreasing in sulfate concentration. In $H_2S$ gas generation test along the depth of sediments there were two different sampling sites which are apart from about 50 cm each other in a menhole. The one has the thickness of 55 cm from the surface, the other, of 60 cm. The hydrogen sulfide gas production rates were measured based on ranges from 0 to 10 cm, 10 to 20 cm, 20 to 30 cm for two samples. The results obtained were 1.08, between 0 to 10 cm in depth for the sample thickness of 55 cm and 3.07, 5.36, $5.42{\mu}g/g-VS{\cdot}hr$ in order of depth for the sample thickness of 60 cm, respectively.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.450-450
• /
• 2011

This study reports the hydrogen sulfide gas sensing properties of ZnO nanorods bundle and the investigation of gas sensing mechanism. Also the improvement of sensing properties was also studied through the application of ZnO heterstructured nanorods. The 1-Dimensional ZnO nano-structure was synthesized by hydrothermal method and ZnO nano-heterostructures were prepared by sonochemical reaction. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) spectra confirmed a well-crystalline ZnO of hexagonal structure. The gas response of ZnO nanorods bundle sensor increased with increasing temperature, which is thought to be due to chemical reaction of nanorods with gas molecules. Through analysis of X-ray photoelectron spectroscopy (XPS), the sensing mechanism of ZnO nanorods bundle sensor was explained by well-known surface reaction between ZnO surface atoms and hydrogen sulfide. However at high sensing temperature, chemical conversion of ZnO nanorods becomes a dominant sensing mechanism in current system. In order to improve the gas sensing properties, simple type of gas sensor was fabricated with ZnO nano-heterostructures, which were prepared by deposition of CuO, Au on the ZnO nanorods bundle. These heteronanostructures show higher gas response and higher current level than ZnO nanorods bundle. The gas sensing mechanism of the heteronanostructure can be explained by the chemical conversion of sensing material through the reaction with target gas.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.11 no.2
• /
• pp.914-922
• /
• 2019

Gas composition has a significant impact on the dispersion behavior and accumulation characteristics of blowout gas. However, few public studies has investigated the corresponding effect of gas composition. Therefore, this study firstly builds the FLACS-based numerical model about an offshore drilling platform. Then several scenarios by varying the composition of blowout gas are simulated while the scenario with the composition of "Deepwater Horizon" accident is regarded as the benchmark. Furthermore, the effects of the gas composition on the flammable cloud volume, the influenced area of flammable cloud, the influenced area of hydrogen sulfide and the critical time of the hydrogen sulfide spreading to the living area are analyzed. The results demonstrate that gas composition is a driving factor for dispersion characteristics of blowout gas. All the results can give support to reduce the risk of the similar accidents incurred by real blowouts.

• Journal of Environmental Health Sciences
• /
• v.14 no.1
• /
• pp.11-22
• /
• 1988

Calcium oxide, lithium oxide and titanium oxide were investigated as additives of zinc oxide for the removal of hydrogen sulfide at high temperature. This experiment was performed in the range of 1.0-2.0 vol.% H$_2$S concentration at 623-873 K reaction temperature, using a thermogravimetric analyzer. A pore blocking model was found to fit the reaction rate and the kinetics data were sucessfully expressed by this model. The reactions between additive sorbents and hydrogen sulfide were first order with respect to hydrogen sulfide concentration in a gaseous mixture with nitrogen. Among the used sorbents, ZnO-CaO 0.5 at.% and ZnO-TiO$_2$ 2.0 at.% sorbents had the best additive effects on the sulfidation reaction between additive sorbents and hydrogen sulfide, whereas the ZnO-Li$_2$O sorbents were ineffective.

• Journal of Korean society of Dental Hygiene
• /
• v.11 no.2
• /
• pp.263-275
• /
• 2011

Objectives : This study was performed analysis of Halitosis components following by subjective cognition of halitosis and Oral State in order to provide basic data for halitosis prevention and establish a device to efficiently eliminate halitosis and analyze the factors that affect the halitosis. Methods : 80 adults were participated who visited at the Dental Clinic in Kyoung-gi do, on the period of the March to September in 2010. The obtained results, through the oral examination, halitosis check and interview, Individually, were as followings. Results : According to the ammonia level was a high relationship between sex, CPI, Tongue plaque, DMFT index which were statistically significant (p<0.05). Total oral gas level was a relationship between VAS, tongue plaque, DMFT index(p<0.05). The Correlation coefficient between the Hydrogen sulfide level and Methyl mercaptan was estimated as r=0.534(p<0.01). As for the multiple regression analysis result, there have been selected dimethyl sulfide and Tongue plaque, Gingival index as factors affecting Bridge, Methyl mercaptan level is as factors affecting Hydrogen sulfide level. Conclusions : There was relationship between the periodontal disease and Ammonia gas component, hydrogen sulfide, dimethyl sulfide, methyl mercaptan. Which were statistically significant total oral gas level and oral variables. Such dental caries as the prevention or early treatment of periodontal disease.

• Structural Engineering and Mechanics
• /
• v.84 no.6
• /
• pp.733-741
• /
• 2022

The amount of natural gas that is used on a worldwide scale is continuously going up. Natural gas and acidic components, such as hydrogen sulfide and carbon dioxide, cause significant corrosion damage to transmission lines and equipment in various quantities. One of the fundamental processes in natural gas processing is the separation of acid gases, among which the safety and environmental needs due to the high toxicity of hydrogen sulfide and also to prevent wear and corrosion of pipelines and gas transmission and distribution equipment, the necessity of sulfide separation Hydrogen is more essential than carbon dioxide and other compounds. Given this problem's significance, this endeavor aims to extend the lifespan of the transmission lines' pipes for gas and oil. Zinc oxide nanoparticles made from the environmentally friendly source of Allium scabriscapum have been employed to accomplish this crucial purpose. This is a simple, safe and cheap synthesis method compared to other methods, especially chemical methods. The formation of zinc oxide nanoparticles was shown by forming an absorption peak at a wavelength of about 355 nm using a spectrophotometric device and an X-ray diffraction pattern. The size and morphology of synthesized nanoparticles were determined by scanning and transmission electron microscope, and the range of size changes of nanoparticles was determined by dynamic light scattering device.

• KSBB Journal
• /
• v.25 no.5
• /
• pp.421-428
• /
• 2010

This paper reports on the experimental investigation carried out to evaluate the physical optimal conditions in the absorption column to remove odorous hydrogen sulfide gas. Hydrogen sulfide gas, as a highly undesirable contaminant, is most widely emitted from environmental treatment facilities. The absorbent mixed with natural second metabolites extracted from conifer trees and chemical absorbent of 2-aminoethanol was applied to remove it via chemical neutralization. The absorbent of natural second metabolites was achieved by a removal efficiency of 20-40% by itself depending on the treatment conditions, but the complex absorbent mixed with 0.1% amine chemical provides the removal efficiency of 98%. The optimal removal efficiencies have been examined against the two major parameters of temperature and pH. This study shows that the aqueous solution by natural second metabolites can be used as an appropriate absorbent in the column absorbed for the removal of hydrogen sulfide gas.