The objectives of this study were (i) to evaluate the effects of temperature and relative humidity on two electrochemical sensors measuring hydrogen sulfide and ammonia using a laboratory testing system for various sensors, and (ii) to propose a calibration method for those concentrations to collect more reliable monitoring data. The effect of temperature and relative humidity was tested under three different conditions, respectively. The linearities measured data under all different conditions for the relative humidity and temperature were excellent, indicating more than 0.99 of R2 for both odor sensors. Under the condition of zero concentration, baselines (intercepts) at zero increased with increasing relative humidity for both hydrogen sulfide and ammonia sensors. The rate of gas concentration according to ADC variation (slopes) increased with increasing relative humidity about only the hydrogen sulfide sensor. In this study, slope, and intercept are utilized for calibration of hydrogen sulfide and ammonia concentration, and the reliability of the data of hydrogen sulfide and ammonia sensors is further enhanced by the relational expression obtained by this paper.

We used three gas sensors to monitor hydrogen sulfide, ammonia, and volatile organic compounds (VOCs), which were frequently emitted from environmental facilities, such as municipal wastewater treatment, livestock manure treatment, and food waste composting facilities. Two electrochemical (EC) sensors for detecting hydrogen sulfide and ammonia, and a photoionization detector (PID) sensor for detecting VOCs were characterized in this study. The performance of their linearity by concentration levels, lower detection limit (LDL), repeatability, reproducibility, precision, and response time were tested under the laboratory condition. The linearity according to concentration levels were favorable for all three sensors with high correlation coefficients (R2 > 0.98). The ammonia sensor showed the highest LDL (18.6 ppb) and the hydrogen sulfide and VOC sensors showed 22.3 ppb and 26.7 ppb of LDL, respectively. The reproducibility and precision were favorable for all three sensors, indicating a lower relative standard deviation (RSD) than 0.9% in the reproducibility test and 7.2% in the precision test. The response times to reach target concentration were varied from 1 to 12 minutes. The ammonia sensor needed 12 minutes of response time at 1 ppm target the NH3 concentration and the hydrogen sulfide and VOC sensors needed less than 2 minutes of response time.

Nickel oxide(NiO) thin films, nanorods, and carbon nanotube(CNT)/NiO core-shell nanorod structures are fabricated by sputtering Nickel at different deposition time on alumina substrates or single wall carbon nanotube templates followed by oxidation treatments at different temperatures, 400 and 700 oC. Structural analyses are carried out by scanning electron microscopy and x-ray diffraction. NiO thinfilm, nanorod and CNT/NiO core-shell nanorod structurals of the gas sensor structures are tested for detection of H2S gas. The NiO structures exhibit the highest response at 200 oC and high selectivity to H2S among other gases of NO, NH3, H2, CO, etc. The nanorod structures have a higher sensing performance than the thin films and carbon nanotube/NiO core-shell structures. The gold catalyst deposited on NiO nanorods further improve the sensing performance, particularly the recovery kinetics.

In this study, we used activated carbon(AC) as a carbon source, along with zeolite, to prepare spherical carbons using sucrose, starch and phenolic resin(PR) as binder material. The physicochemical characteristics of the three samples(AZ4P, AZ6P and AZ8P) were examined by BET, XRD, SEM, EDX, H2S/NH3 gas adsorption, compressive strength and ignition test techniques. Through comparative analysis of the compressive strength and ignition test results the AZ8P sample was found to have the best hardness and the highest temperature resistance capacity. After activation, the AZ8P sample had the best H2S adsorption capacity, and AZ6P was the most suitable for the adsorption of ammonia.

This paper presents the results of a human health effect for H2S emission standard of incinerators in Seoul, Korea. The four selected incinerators of Gangnam, Mapo, Nowon and Yangcheon were chosen as the domains of study. Air dispersion modelling (AERMOD) was used to predict the ground level concentration within 3 km distance of the emission source. The emissions at the incinerators studied ranged from 0.0721 (Yangcheon) to 0.3007 g/s (Gangnam). These values were about three orders of magnitude smaller than that of Canadian geothermal power plants. Based on the health risk assessment, different health risks were identified for short-term and long-term dispersion of the studied areas. The short-term hazard quotient (HQ) for H2S of Gangnam and Nowon incinerators were greater than the acceptable limit (i.e., 1.0) in some locations. However the long-term HQ for H2S of all incinerators were lower than the acceptable limit.

The study analyzed performance assessment factors of odor sensors from 4 different manufacturers, including minimum detection limit, humidity stability and temperature stability. In the minimum detection limit assessment, only one electrochemical gas sensor was able to detect ammonia and hydrogen sulfide at the concentration of 5 ppb. The standard deviation ratio was over 10%, and it increased as humidity rose. The range of temperatures in which the electrochemical and photoionization gas sensors could function well was between 25oC and 40oC, and the sensor output values were unstable at low temperatures. Regarding the temperature stability of the metal oxide semiconductor sensor for measuring complex odors, the sensor output values dropped considerably to 0~10oC, and were similar to the concentrations of odor gases generated at 25oC. The results of the test of odor sensor outputs after temperature and humidity pre-treatment revealed that the respective stable output values at 50% humidity and 25oC were similar to the concentrations of manufactured odors. In terms of temperature and humidity stability of the NH3, H2S and Complex odor sensors, all target substances had stable output values at 25~40oC and 50~65% relative humidity, and unstable values at low temperatures and high humidity. Therefore, implementing pretreatment systems including temperature and humidity correction (25~40oC, 50~65% RH) is necessary for the stable use of odor sensors.

정수슬러지를 탄화 및 활성처리하여 흡착제를 제조하였으며, 이를 이용한 황화수소 흡착특성을 고찰하였다. 제조 된 흡착제에 대한 BET측정 및 SEM 등 물성분석을 실시하였으며, 황화수소를 대상으로 회분식의 흡착평형실험 을 실시하였다. 실험변수로는 활성처리시 적용되는 약품종류 및 농도 등이 적용되었다. 실험결과, 정수슬러지는 탄화나 약품첨착과정을 통해 커다란 성능 향상이 이뤄짐을 알 수 있었다.

This study reports the effects of H2S gas concentration on the properties of Cu2ZnSnS4(CZTS) thin films. Specifically, sulfurization process with low H2S concentrations of 0.05% and 0.1%, along with 5% H2S gas, was studied. CZTS films were directly synthesized on Mo/Si substrates by chemical bath deposition method using copper sulfate, zinc sulfate heptahydrate, tin chloride dihydrate, and sodium thiosulfate pentahydrate. Smooth CZTS films were grown on substrates at optimized chemical bath deposition condition. The CZTS films sulfurized at low H2S concentrations of 0.05 % and 0.1% showed very rough and porous film morphology, whereas the film sulfurized at 5% H2S yielded a very smooth and dense film morphology. The CZTS films were fully crystallized in kesterite crystal form when they were sulfurized at 500 oC for 1 h. The kesterite CZTS film showed a reasonably good room-temperature photoluminescence spectrum that peaked in a range of 1.4 eV to 1.5 eV, consistent with the optimal bandgap for CZTS solar cell applications.

H2S is a flammable toxic gas that can be produced in plants, mines, and industries and is especially fatal to humanbody. In this study, CuO nanowire structure with high porosity was fabricated by deposition of copper on highly porous single-wall carbon nanotube (SWCNT) template followed by oxidation. The SWCNT template was formed on alumina substrates bythe arc-discharge method. The oxidation temperatures for Cu nanowires were varied from 400 to 800oC. The morphology andsensing properties of the CuO nanowire sensor were characterized by FESEM, Raman spectroscopy, XPS, XRD, and current-voltage examination. The H2S gas sensing properties were carried out at different operating temperatures using dry air as thecarrier gas. The CuO nanowire structure oxidized at 800oC showed the highest response at the lowest operating temperatureof150oC. The optimum operating temperature was shifted to higher temperature to 300oC as the oxidation temperature waslowered. The results were discussed based on the mechanisms of the reaction with ionosorbed oxygen and the CuS formationreaction on the surface.

The contents of this paper is to develop a passive sampler for H2S measurement. When the H2S gas exists in the air, AgNO3 solution coated filter of white used phenomenon which is exchanged with black. If the H2S gas concentration increased, the color of AgNO3 solution coated filter is discolored more black. H2S passive sampler measures the H2S gas concentration by changed color of AgNO3 solution coated filter. The reproducibility of the H2S passive sampler is very stable to within an error 5%RSD. The black color of AgNO3 solution coated filter showed a linear relationship with the H2S gas concentrations. In addition, correlation of the developed CDM and CR-10(Minolta, Japan) showed a high correlation to 0.99. Manufactured H2S passive sampler must be kept refrigerated, stability and reactivity was observed for up to 20 days

H2S adsorption characteristics of adsorbent made by coffee waste were investigated. For analyses of the manufactured adsorbent, various methods such as scanning electron microscope(SEM), measurements of BET(Brunauer Emmett Teller) surface area, pH, and Iodide adsorption were adopted. As major adsorption characteristics, adsorption equilibrium capacity was measured by using a batch type experimental apparatus for operating variables such as adsorption temperature(25～45℃), adsorbent types. The experimental result showed that the H2S adsorption equilibrium capacity of adsorbent made by coffee waste much more increases with steam activation for the coffee waste.

This study was carried out to investigate the response characteristics of a hydrogen sulfide electrochemical gassensor for several wastewater odors. At first, it was found that bubbling sampling method was superior toheadspace sampling method in terms of sensor sensitivity. High correlation between odor concentration and sensorresults was shown for two wastewater which were r=0.977 for food-waste recycling wastewater and r=0.997for food industry wastewater. On the other hand, no correlation (r=0.258) was found for plating wastewater,because hydrogen sulfide was not the main odorant for that.

H2S adsorption characteristics of adsorbent made by fallen leaves were investigated. For analyses of the manufactured adsorbent, various methods such as scanning electron microscope(SEM) and measurements of BET surface area were adopted. As major adsorption characteristics, adsorption equilibrium capacity was measured by using a batch type experimental apparatus for operating variables such as adsorption temperature(25~45℃) and adsorbent types. The experimental result showed that the H2S adsorption equilibrium capacity of adsorbent made by fallen leaves decreased with increasing adsorption temperature due to physical adsorption phenomena. It was also found that the H2S adsorption capacity of the adsorbent increased remarkably by an acid treatment with HCl solution.

황화수소가 고분자 전해질막 연료전지의 연료극에 공급되었을 때 전지 성능의 저하와 황화수소 피독 후 순환전류 전압법(CV) 스캔을 통해 전지의 성능 회복에 관한 연구를 수행하였다. 수소에 30 ppm의 황화수소를 희석하여 연료극에 공급하고 전류밀도를 0.5A/cm2로 고정하여 1시간 동안 3차례 피독한 후 CV를 5회 스캔하여 단위전지의 성능회복을 확인한 결과 피독 전 단위전지의 초기 성능은 0.60 V에서 1.16A/cm2이였으며, 30 ppm의 황화수소를 한 시간 동안 피독한 결과 0.77A/cm2로 그 성능이 감소하였고, 피독 횟수가 증가함에 따라 성능이 0.57 V까지 감소하였다. 그리고 황화수소 피독 후 각 스텝에서 CV 스캔을 5회 실시하였을 때 단위전지의 성능이 90.3%까지 회복하는 것을 알 수 있었다. 또한, 황화수소 피독 후 단순히 고순도의 수소 가스만 연료극에 주입하여도 약 80% 정도의 성능회복이 가능하였다. 이러한 현상으로 판단할 때 황화수소 가스의 백금 촉매층에의 흡착은 그리 강하지 않음을 알 수 있었다.

H2S adsorption characteristics of adsorbent made by drinking water treatment sludge were investigated. For analyses of the manufactured adsorbent, various methods such as scanning electron microscope(SEM), measurements of BET surface area were adopted. As the major adsorption characteristic, breakthrough curve was measured by using a continuous fixed bed adsorption column for operating variables such as aspect ratio(L/D, 3∼9), gas flow rate(0.2∼1.0 liter/min) and type of samples. The experimental results showed that the breakthrough pint decreased with increasing gas flow rate, but increased with increasing aspect ratio. It was also found that the physical and chemical treatments of drinking water treatment sludge are very important for the improvement in H2S adsorption capacity due to property changes of the sludge.

폴리이미드는 유리상 고분자로서 높은 화학적 저항성과 열적 안정성을 지니고 있으며, 기계적 물성이 거의 변하지 않는다. 본 연구에서는 황화수소와 메탄의 투과특성을 알아보기 위하여 폴리이미드 중공사막을 건/습식 상전이 공정에 의하여 제조하였고, 제조된 중공사막의 구조 및 실리콘 코팅 전/후의 황화수소와 메탄의 투과특성에 대하여 알아보았다. 압력이 증가함에 따라 황화수소의 투과도는 가소화 현상으로 인해 증가하였고, 황화수소와 메탄의 선택도 역시 증가하는 것으로 나타났다. 실험에 사용된 세 종류의 막 가운데 KSM03b의 투과도와 KSM03d의 선택도가 가장 높은 것으로 나타났다. air gap이 증가 할수록 투과도는 감소하지만 선택도는 증가하였다. 또한 실리콘 코팅 후 투과도는 감소하였지만, 선택도는 증가하였고 7기압에서 KSM03d의 선택도는 275이었다.

The likelihood of failure by the corrosion of high temperature H2S/H2, which affect to a risk of facilities, was analyzed through the risk based-inspection using API-581 BRD. We found that the corrosion rate was increased as temperature and H2S concentration were increased. Also, the technical module subfactor(TMSF) was increased as an used you increased, material thickness decreased, inspection number decreased, and inspection effectiveness increased. In these conditions, the maximum value of TMSF was not varied, but the TMSF was sensitively varied at low temperature for high concentration of H2S.