Polymer electrolyte membrane fuel cell (PEMFC) performance degrades when hydrogen sulfide (H2S) is present in the fuel hydrogen gas; this is referred to as H2S poisoning. This paper reveals H2S poisoning on PEMFC by measuring electrical performance of single cell FC under various operating conditions. The severity of H2S poisoning depended on H2S concentration under best operating conditions(65℃ of cell temperature and 100% of anode humidification). H2S adsorption occured on the surface of catalyst layer on MEA, but not on the gas diffusion layer(GDL) by analyzing SEM/EDX data. In addition, MEA poisoning by H2S was cumulative but reversible. After poisoning for less than 150 min, performance of PEMFC was recovered up to 80% by just inert nitrogen gas purging.

The purpose of this study is to estimate concentration and emission unit of ammonia and hydrogen sulfide released from domestic chicken buildings by field investigation. Mean concentrations of ammonia and hydrogen sulfide emitted from chicken buildings were 18.25(±4.78)ppm and 807.53(±526.17)ppb for caged layer house, 14.48(±4.13)ppm and 644.82(±312.48)ppb for broiler house, and 6.16(±2.02)ppm and 284.75(±232.08)ppb for layer house with manure belt, respectively. Mean emission coefficients of ammonia and hydrogen sulfide were 0.951(±0.131) g hen^-1h^-1 and 2.956(±0.968) mg hen^-1h^-1 based on head whereas they were 0.575(±0.082) g m^-2h^-1 and 12.44(±3.536) mg m^-2h^-1 based on time. In conclusion indoor concentration and emission coefficient of ammonia and hydrogen sulfide were highest in caged layer housed, followed by broiler house and layer house with manure belt.

This study pointed out problems on the operation by estimating process efficiency to the 3N-system(quick fermentable treatment process) which occupy plant to treat swine wastewater more than about 30 % in Jeju. And the parts to improve from problems were deduced and introduced those in situ. When the parts to improve from problems were not introduced, the Concentration of H₂S and NH₄ was 5 and 50ppm in the fermenter, respectively. But the concentration of H₂S and NH₃ was shown N.D. and 1~2 ppm in the fermenter after introduction. The concentration of H₂S and NH₃ were measured by 16 and 300 ppm highly in the aeratin tank before improvement, but those were shown N.D. and 0~1 ppm after improvement, respectively. Therefore, it showed possibility which could decrease odor efficiently with low cost by this study in 3N-system.

V2O5-TiO2 catalysts were prepared by various methods. V2O5-TiO2 were prepared by sol-gel method with different drying conditions (aerogel and xerogel), and V2O5 supported on TiO2 obtained by sol-gel method with precipitation-deposition method and impregnation method. The performance of the V2O5-TiO2 catalysts was investigated for the selective oxidation of hydrogen sulfide in the stream containing both ammonia and excess water. All the catalysts showed good dispersion of vanadium and they had high H2S conversion with no or little production of sulfur dioxide. The V2O5-TiO2 aerogel catalyst prepared by sol-gel method with drying under super critical condition had the highest surface area which led to better catalytic activity compared to those by other synthesis methods.

지구온난화 문제와 유기성 폐기물의 처리문제는 해결이 시급한 환경문제이며, 바이오가스는 이러한 문제를 동시에 해결할 수 있는 장점으로 크게 주목받고 있다. 그러나 바이오가스 중에 함유된 황화수소나 암모니아는 발전설비의 부식 및 대기오염을 유발하기 때문에 전처리가 필수적이다. 기체상 오염물질의 처리를 위한 다양한 기술 중 수세정(scrubber)은 기액간의 접촉을 유도하여 액상으로 오염물질을 흡수 및 제거하는 기술로 널리 활용되고 있는 기술이다. 또한 황화수소나 암모니아는 물에 대한 용해성이 높기 때문에 수세정 공정을 활용하기 유리하다. 그러나 고농도의 황화수소나 암모니아를 효율적으로 처리하기 위해 가성소다 등의 약품을 세정액에 용해시켜 활용하는 것은 세정 후 약액의 2차 처리문제를 야기한다. 이에 본 연구에서는 이러한 문제점을 해결하기 위해 수세정공정에 전기화학적으로 생성된 free chlorine을 유입시켜 흡수된 황화수소 및 암모니아를 산화함으로써 물질전달률을 높일 수 있도록 하고자 하였다. 이를 위해서는 황화수소와 암모니아의 물질전달률의 평가가 필수적이며, 본 연구에서는 10mM의 NaCl이 용해된 수용액에 1,000 ppm의 황화수소와 암모니아가 4 L/min의 유량으로 단독으로 유입될 때와 동시에 유입될 때의 물질전달계수를 비교하였다. 수용액의 pH가 8일 때 황화수소 단독 물질전달계수(KLa-H2S)는 0.1214 min-1이고, 암모니아 단독 물질전달계수(KLa-NH3)는 9.9×10-5 min-1으로 산정되었다. 그러나 황화수소와 암모니아 각 1,000 ppm이 동시에 유입되었을 때 KLa-H2S는 0.2247 min-1, KLa-NH3는 1.6×10-4 min-1으로 물질전달속도가 상승하였다. 따라서 수세정 공정에서 황화수소와 암모니아의 동시유입이 제거율의 향상에 도움이 되는 것으로 나타났다. 또한, free chlorine에 의해 액상 황화수소와 암모니아가 제거된다면 추가적인 물질전달계수의 향상이 가능하다.

가축분뇨, 하수슬러지, 음식물류폐기물 등의 유기성폐자원을 이용한 바이오가스의 생산은 기존에 버려지고 있던 유기성폐기물을 에너지화 할 수 있을 뿐만 아니라 동시에 온실가스를 감축할 수 있다는 점에서 각광받고 있다. 혐기성 소화조에서 발생하는 바이오가스에는 메탄(CH4)이 60~65%정도를 이루고 이산화탄소(CO2)가 30~35%이며, 미량 가스로 황화수소(H2S), 수분(Vapor) 등이 포함되어 있다. 바이오가스 중에 미량 존재하는 황화수소는 그 유독성이 매우 심하고, 촉매의 활성과 바이오가스의 이용효율을 저하시키며, 배관재질과 반응하여 설비를 부식시키고 연소 후에는 SO2로 산화하여 산성비의 원인 물질로 배출되어 대기 환경을 오염시키는 역할을 하고 있어 그 제거가 필수적이라 할 수 있다. 바이오가스 중에 황화수소 가스는 메탄발효 원료 중에 포함되어 있는 단백질과 아미노산을 구성하는 황과 황산염을 환원하는 황환원세균 등에 의하여 생성하는 유해가스이다. 따라서 원료 물질의 구성에 따라 황화수소의 농도가 달라지며, 황 함유량이 높은 하수슬러지를 이용한 바이오가스 생산설비에서는 황화수소 농도가 2,000 ppm을 상회한다. 이러한 황화수소를 제거하기 위한 정제방법으로는 습식, 건식, 생물이용 등으로 나누어지고 있으며, 처리 가스량, 유지관리비, 탈황 목표치 등을 감안하여 각각의 적정 방법을 선택하여 적용하고 있다. 이러한 황화수소의 거동을 파악하여 바이오가스 생산 및 이용 효율성을 증대시키고자, 국내 바이오가스 플랜트의 탈황설비를 중심으로 정밀 모니터링을 실시하였다.

This study was carried out to examine the characteristics of hydrogen sulfide adsorption using an iron hydroxide-based adsorbent. The prepared adsorbent was discussed with regard to its adsorption capacity and analyzed via surface analysis methods to illustrate the physical characteristics of hydrogen sulfide adsorption. As the drying temperature increased, the adsorption capacity of the adsorbent decreased from 29.15wt% to 22.73wt%. The adsorption capacity was decreased as the space velocity increased and showed an adsorption capacity of about 3.65 at 3,157.6 h−1. The effect of sulfur dioxide was to decrease the adsorption capacity from 29.15wt% to 27.94wt%. The adsorbent exhibited the amorphous type in its physical appearance based on XRD and EDS analysis.

Biogas has been used to remove water content and hydrogen sulfide (H2S). Removing water requires a low temperature process; thus, our study investigated removing H2S under high pressure and low temperature. Several experiments were conducted to investigate removal of H2S from a biogas stream by optimizing chemical absorption and the chemical reaction with a Fe/EDTA solution. The roles of Fe/EDTA were studied to enhance removal efficiency of H2S due to oxidization by Fe+3/EDTA. The objective of this study was to explore the feasibility of enhancing toxic gas treatment in a biogas facility. A biogas purification strategy affords many advantages. For example, the process can be performed under mild environmental conditions and at low temperature, and it removes H2S selectively. As the Fe-EDTA concentration increased, the H2S conversion rate increased because the Fe-EDTA complex was highly stable. The optimal pH to stabilize the chemical complex during oxidation of H2S was 9.0.

Concentrations of hydrogen sulfide in ambient air have been measured from January 2014 to June 2016 in a coastal area near the Ulsan National Industrial Complex. The measurement sites were 1 km, 2.6 km, 5.6 km, and 20 km away from a kraft pulp mill, which is located at the most southern edge of the complex. Concentrations above 0.4 ppb were monitored every 5 min and the highest concentration of the day was determined. From a total of 775 measurement days, hydrogen sulfide concentrations > 20 ppb were recorded on 36 and 38 days at the measurement site closest to the mill and the residential area 2.6 km away from the mill, respectively. At the site farthest from the mill, the concentrations were always 20 ppb lower than the malodor regulation for the residential area but sometimes higher than the odor recognition threshold for hydrogen sulfide. Although several emission sources of hydrogen sulfide have been published in the Pollutant Release and Transfer Register of Korea, the kraft pulp mill is considered to be the biggest contributor of atmospheric hydrogen sulfide in the southern coastal area of Ulsan.

The purpose of the present study is to examine characteristics of hydrogen sulfide adsorption using iron-activated carbon composite adsorbents prepared by ferric nitrate and ferric chloride. Prepared adsorbents were discussed on H2S adsorption capacity. Also, adsorbents were analyzed by surface analysis methods for illustrating the physical characteristics of H2S adsorption. The breakthrough tests of H2S were conducted at 3,333 ppm of inlet concentration, demonstrating that the adsorption capacity for iron-activated carbon composite adsorbents was in order of FC_AC (Ferric chloride_Activated carbon), FN_AC (Ferric nitrate_Activated carbon), FC (Ferric chloride) and FN (Ferric nitrate). Adsorption capacity of FC was 0.06 g/g, whereas FC_AC showed the highest capacity of 0.171 g/g. All adsorbents exhibited the amorphous type in physical appearance based on XRD analysis and high Fe content based on EDS analysis. The surface areas of composites were increased by adding activated carbon, exhibiting better adsorption capacity.

Several experiments have done to investigate the removal of hydrogen sulfide(H2S) synthetic gas from biogas streams by means of chemical absorption and chemical reaction with 0.1 M – 1 M Fe/EDTA solution. The hydrogen sulfide of biogas was bubbled through an gas-lift column with Fe/EDTA resulting in the formation of sulfur particles. Wide range of optimal operating conditions were tested for both Fe/EDTA solution and the biogas, and the optimal ratio of Fe/EDTA concentration for efficient removal of hydrogen sulfide was found. The roles of Fe/EDTA were studied to enhance the removal efficiency of hydrogen sulfide because of oxidizing by Fe+3/EDTA. 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 of with minor potential for further pollution. The process to address over 90% removal efficiency of hydrogen sulfide does offer considerable advantages unrealized.

Odor from sewage treatment plants have the potential to cause significant annoyance and to impact the amenity. In this study, odor emission characteristics at unit process of 48 sewage treatment facilities in 39 plants were evaluated using composite odor concentration and hydrogen sulfide (H2S) concentration. The values of composite odor concentration (geometry mean) and H2S concentration (median) for sludge treatment processes are higher than those for the other treatment processes. The composite odor concentration and H2S concentration are distributed over a wide area in each process. Composite odor concentration (dilution ratio) was found to have the significant correlation with H2S concentration (p=0.000<0.05). The H2S concentration accounted for 67.1% of composite odor concentration.

A packed bed of volcanic rock was used as deodorizing material to remove hydrogen sulfide(H2S) from air in a laboratory-scale column, and was inoculated with Thiobacillus sp. as H2S oxidizer. The effects of volcanic rock particle size distribution on system pressure drop were examined. Various tests have been conducted to evaluate the effect of H2S inlet concentration and EBCT(Empty Bed Contact Time) on H2S elimination. The pressure drop for particles of size range from 5.6 to 10 ㎜ was 14 ㎜H2O/m at a representative gas velocity of 0.25m/s. Biofilter using scoria and Thiobacillus sp. could get the stable removal efficiencies more than 99.9% under H2S inlet concentrations in the range from 30 to 1,100ppm at a constant gas flow rate of 15.2 ℓ/min. H2S removal efficiencies greater than 99% were observed as long as EBCT was longer than 8sec at the 250ppm of H2S inlet concentration. When EBCT was reduced to 5.5 sec, H2S removal efficiency decreased by about 12 percent. The maximum H2S elimination capacity was determined to be 269g-H2S/㎥·hr.