• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.543-553
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• 1996

Oxygen reduction in an alkaline fuel cell was studied by using perovskite type oxides as an oxygen electrode catalyst. The high surface area catalysts were prepared by malic acid method and had a formula of $La_{0.6}Sr_{0.4}Co_{1-x}Fe_xO_3$(x=0.00, 0.01, 0.10, 0.20, 0.35 and 0.50). From the result of XRD pattern and specific surface area due to the amount of Fe substitution and the consumption of ammonia-water, the complex formation of Fe ion with $NH_3$ was the main factor for both the phase stability of perovskite and the increase of specific surface area. Multi-step calcination was necessary to give a single phase of perovskite in catalyst precursor. The crystal structure of the catalysts was simple cubic perovskite, which was verified from the XRD patterns of the catalysts. The activity of oxygen reduction was monitored by the techniques of cyclic voltammetry, static voltage-current method, and current interruption method. The activity(current density) of oxygen reduction showed its minimum at x=0.01 and its maximum between 0.20 and 0.35 of x-value in $La_{0.6}Sr_{0.4}Co_{1-x}Fe_xO_3$. This tendency was independent of the change of surface area.

• Journal of Power System Engineering
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• v.14 no.6
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• pp.13-19
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• 2010

이 논문에서는 디젤자동차용 LNT와 SCR 촉매의 NO, $NH_3$ 흡착 및 탈리의 기본 특성과 수열화 온도와 시간 및 정량화된 황피독 농도에 대한 de-$NO_x$ 촉매의 내구성을 평가하였다. LNT 촉매는 열적으로 열화됨에 따라 Pt 및 Ba의 소결 및 응집으로 활성이 떨어져 $NO_x$ 전환율은 감소하였다. 반면에 Pt의 비활성화로 중간생성물인 $NH_3$ 생성량은 증가하였으며, 이때 생성된 $NH_3$는 LNT+SCR 복합시스템의 SCR 촉매의 환원제 역할을 담당한다. 1.0 g/L 이상의 황이 피독된 LNT 촉매는 탈황을 하여도 질소 산화물 흡장물질(Ba) 의 성능이 회복이 되지 않아 $NO_x$ 전환율은 회복되지 않았으며, 탈황 후 Pt 재활성화로 인해 NO2 및 SCR 환원제인 $NH_3$ 생성량은 증가하였다. SCR 촉매의 $NO_x$ 전환율은 $700^{\circ}C$ 36h, $800^{\circ}C$ 24h로 수열화 시킨 촉매는 전이금속 입자 성장 및 zeolite 구조 파괴로 인하여 급격하게 떨어졌으며, 0.36 g/L 황 피독된 촉매는 zeolite가 가지는 강산성 특정으로 내피독성이 강하여 탈황시 $NO_x$ 전환율은 회복되었다.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.3
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• pp.304-311
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• 1999

This experiment was conducted to find out the optimum condition of aeration rates for removal of malodor and to improve the compost quality. The aspect of ammonia emission and amounts of volatilization were investigated in the enclosed composting reactor of 242 liters piled with mixed materials of dairy manure and rice straw, which adjusted to 65% of initial moisture content and controlled by four different aeration rates. Mature temperature increased suddenly in initial composting time and decreased with Increasing aeration rates. The treatment of $1.79l\;min^{-1}kg\;dry-solids^{-1}$ results in overcooling and rapid drying of composting materials because of too much aeration. The average concentration of ammonia emitted from composting for 24 days was the range of 25.3 to $239.8mg\;l^{-1}$ and was highest in the treatment of $0.09l\;min^{-1}kg\;dry-solids^{-1}$, followed by 0.90. 0.18 and $1.79l\;min^{-1}kg\;dry-solids^{-1}$. The range of maximum concentration by different aeration rates was $335{\sim}2279mg\;l^{-1}$ and it wan highest in the treatment of $0.09l\;min^{-1}kg\;dry-solids^{-1}$, followed by 0.18, 0.09 and $1.79l\;min^{-1}kg\;dry-solids^{-1}$. Relationship between the ammonia concentration emitted and temperature matured under different aeration rates showed an exponential positive correlation with 1% significance and had a trend of clear increase in ammonia concentration with increasing temperature over $50^{\circ}C$. Most of ammonia volatilized within plays after composting. The volatilization rate of ammonia ranged from 0.056 to 0.453 per dry solids of materials and it was highest in the treatment of $0.09l\;min^{-1}kg\;dry-solids^{-1}$, followed by 0.18, 0.09 and $1.79l\;min^{-1}kg\;dry-solids^{-1}$. Amounts of ammonia volatilized under composting condition of this experiment was estimated to be highest in the aeration range of 0.9 to $1.0l\;min^{-1}kg\;dry-solids^{-1}$.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.1
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• pp.103-110
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• 2017

In Concentrated Animal Feeding Operations(CAFOs), emission of ammonia from stored manure contributes negatively on the wellness of livestock. In CAFOs facilities, indoor aerial ammonia concentration oftentime surpasses the critical level potentially harmful to livestock's immune system. Understandably, numerous researches to control aerial ammonia have been conducted in countries where CAFOs were practiced for many decades. Some innovative technologies, such as scrubber, bio-filter, and additives emerged, as a result. Among them, microbial additives became popular in Korea, due to an easiness of use and affordability. However, microbial additives still have some weaknesses. Their price is still high enough to discourage farmers who run a small scale farm and their effectiveness are still questioned by many users and researchers. In the present study, we found soluble carbohydrates, such as sugar, glucose, and molasses, when supplemented to pig slurry manure, can mitigate ammonia emission. To be more specific, pig manure slurry(120kg), stored in container(200L), was supplemented with sugar at 0.1%(w/w) and was, subsequently, monitored for pH and aerial ammonia for next 10 days. From this experiment, it was found that the sugar supplementation was effective in mitigating the aerial ammonia concentration (33% in average) when monitored daily. Also, the pH of manure slurry was maintained at relatively low level(8.2) in sugar-supplemented manure slurry while it was elevated to 8.5 in untreated slurry. Conclusively, the obtained data suggest that soluble carbohydrate can mitigate ammonia emission by acidifying manure slurry. Additionally, it can be suggested that soluble carbohydrates, such as sugar, glucose, and molasses, can be reasonable choices for animal farmers who have been looking for an alternative choice to replace expensive microbial additives.

• Journal of Animal Science and Technology
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• v.48 no.3
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• pp.401-414
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• 2006

Twenty eight Holstein steers 12 months old and weighing about 300kg were andomly allotted into one of four groups being fed ammoniated rice straw(ARS) and substituted 30%, 40% and 50% crushed bamboo chip for ARS to determine the effects of different levels of bamboo chip on performance, digestibility and carcass characteristics. Daily weight gain was reduced as the substitution levels of bamboo chip for ARS as a roughage source increased but there were no differences in daily weight gain between steers fed ARS alone and 30% bamboo chip for ARS. Concentrates intakes were not different between treatments by the substitution levels of bamboo chip for the whole fattening period. Roughage intake tended to increase as the substitution levels of bamboo chip increased. Total feed intake was not affected by the substitution levels of bamboo chip. However, feed efficiency got worse with increasing levels of bamboo chip. Animals fed the roughage substituting 30% bamboo chip for ARS were higher in profit by 13% than animals fed ARS alone as a roughage source. Digestibilities of Dry matter(DDM) and crude fiber(DCF) were highest in animals fed ARS alone as a roughage source. DDM's were lower in higher substitution levels of crushed bamboo chip but there were no differences in DCF among animals fed different levels of bamboo chip as a roughage source. Crude protein digestibility was not affected by ammoniated rice straw or by the different levels of bamboo chip. Dressing percentage and backfat thickness were not affected by ammoniated rice straw or by the levels of bamboo chip but ribeye area was narrowed as the levels of bamboo chip increased. Beef color, fat color, texture, maturity and marbling score were not affected by feeding of ammoniated rice straw or by the levels of bamboo chip. According to these results, it may be concluded that profit can increase when Holstein bulls are castrated and roughage containing ammoniated rice straw plus 30% bamboo chip is offered.

• Clean Technology
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• v.26 no.2
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• pp.137-144
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• 2020

Metal-impregnated activated carbons were prepared via ultrasonic-assisted impregnation method for regeneration and low ammonia concentration. Magnesium and copper were selected as metals, while chloride (Cl^-) and nitrate (NO₃^-) precursors were used to impregnate the surface of activated carbon. The physical and chemical properties of the prepared adsorbents were characterized by TGA, BET, and NH₃-TPD. The ammonia breakthrough test was carried out using a fixed bed and flowing ammonia gas (1000 mg L^-1 NH₃, balanced N₂) at 100 mL min^-1, under conditions of temperature swing adsorption (TSA) and pressure swing adsorption (PSA, 0.3, 0.5, 0.7, 0.9 Mpa). The adsorption and desorption performance of ammonia were in the order of AC-Mg(Cl) > AC-Cu(Cl) > AC-Mg(N) > AC-Cu(N) > AC through NH₃-TPD and TSA and PSA processes. AC-Mg(Cl) using MgCl₂ showed the average adsorption amount of 2.138 mmol/g at TSA process. Also, AC-Mg(Cl) showed the highest initial adsorption amount of 3.848 mmol/g at PSA 0.9 Mpa. When metal impregnated the surface of the activated carbon, it was confirmed that not only physical adsorption, but also chemical adsorption increased, making enhancement in adsorption and desorption performances possible. Also, the prepared adsorbents showed stable adsorption and desorption performances despite repeated processes, confirming their applicability in the TSA and PSA processes.

• Journal of The Korean Society of Grassland and Forage Science
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• v.27 no.3
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• pp.197-208
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• 2007

This study was carried out to investigate effects of increasing moisture content with or without supplementing inoculant (Lactobacillus plantarum) in TMR (total mixed ration) on its feed value. In case of exposing TMR to air, the lower the moisture level of TMR was, the less its apparent condition was changed. The time of spreading of molds tended to be faster in TMR with the higher moisture level. And also the odor was influenced by moisture content and inoculant supplement that is, sour odor was smelled from 24 hour after exposing TMR containing 35% and 50% moisture to air, but TMR supplemented with inoculant had sweet odor. The inner temperature of TMR containing 35% and 50% moisture without inoculant tended to increase continually after the lapse of 6 hours when the TMR was exposed to air. The inner temperature of TMR containing 35% moisture with inoculant tended to increase dramatically after the lapse of 48 hours when exposed to air, but that of TMR containing 50% moisture with inoculant tended to increase after 6 hours. The pH of TMR containing 15% was consistent regardless of exposing time to air, but that of TMR containing 35% and 50% moisture considerably increased after 12 and 24 hours, respectively. The concentration of $NH_3-N$ of TMR supplemented with inoculant was increased from 6 hours after exposure to air, while that or TMR without inoculant increased from 12 hours. Nutrient content or TMR tended to be increased with the increase of exposing time to air and storage time under sealed condition.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.11
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• pp.613-625
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• 2017

For two agricultural reservoirs that are rented for fishing spots, benthic nutrient fluxes experiment were performed two times with two sediments from fishing-effective zone and one sediment from fishing-ineffective zone using laboratory core incubation in oxic and anoxic conditions. During benthic nutrient fluxes experiment, the changes in DO, EC, pH, and ORP in the supernatant were not significantly different between fishing-effective zone and fishing-ineffective zone, and were similar to the sediment-hypolimnetic diffused boundary layer in agricultural reservoir. Except for $NO_3{^-}-N$, more benthic nutrient fluxes of $NH_4{^+}-N$, T-P, and $PO{_4}^{3-}-P$ from sediment to hypolimnetic was measured in anoxic than in oxic conditions (p<0.05). As the DO concentration in hypolimnetic decreases, the microorganism-mediated ammonification is promoted, the nitrification is suppressed, and finally the $NH_4{^+}-N$ diffuses out from sediment to hypolimnetic. Also, the diffusion of T-P and $PO{_4}^{3-}-P$ from sediments to hypolimnetic is accelerated through the dissociation of the phosphorus bound to both organic matters and metal hydroxides. The difference in the benthic nutrient diffusive fluxes between fishing-effective zone and fishing-ineffective zone was not statistically significant (p>0.05). Therefore, it was found that fishing activities did not increase the benthic nutrient diffusive fluxes to a statistically significant level. Due to the short fishing activities of 10 years and the rate-limited diffusion of the laboratory core incubation, the contribution of fishing activities on sediment pollution is estimated to be low. No significant correlation was found between the total amount of nutrients in sediment and the benthic nutrient diffusive fluxes in both aerobic and anaerobic conditions. Therefore, nutrients input from various nonpoint sources of watersheds are considered to be a more dominant factor rather than fishing activities in water quality deterioration, and both aeration and water circulation in hypolimnetic were required to suppress the anoxic environment in agricultural reservoirs.

• 한국해양학회지
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• v.25 no.1
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• pp.8-20
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• 1990

A series of pore water data were obtained during the different time over one year period between October 1987 and October 1988, from a site on a muddy intertidal flat, located in the Kyeong-gi Bay, west coast of Korea, The results have revealed that the tidal flat is an environment of active nutrient the subface supplied by the overlying seawater is almost completely removed from the pore water at depth of about 10 cm below the sediment surface. The nutrients such as ammonium and phosphate are produced through this process and subsequently accumulated in the pore water forming steep gradients near the sediment surface. Below the main sulfate redirection zone, a secondary peak of dissolved sulfate was often observed. Greal seasonal variation of the pore water nutrient profiles was observed, which was particularly clear in their maximum concentration as well as in their concentration gradient. The rate constants of sulfate reduction and nutrient regeneration, estimated by using a diagenetic model (Berner, 1980), differ by an order of magnitude between the summer and winter seasons. The difference in sediment temperature may account for most of the calculated variation. The C:N:P ratio, calculated from the pore water nutrient gradients also exhibits a slight seasonal difference. The organic matter being decomposed by sulfate reduction appears to be depleted in depleted in nitrogen, compared to the average marine organic matter.

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.391-396
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• 2015

To investigate the effect of the catalyst synthesis method on the oxidative dehydrogenation (ODH) of nbutenes, $BiFe_{0.65}MoP_{0.1}$ oxide catalysts were prepared with various synthesis methods such as co-precipitation, citric acid method, hydrothermal method, and surfactant templated method. The catalysts were characterized by X-ray Diffraction (XRD), $N_2$ sorption, and $NH_3/1$-butene-temperature programmed desorption ($NH_3/1$-butene-TPD) to correlate with catalytic activity in ODH reaction. Among the catalysts studied here, $BiFe_{0.65}MoP_{0.1}$ oxide catalyst prepared with co-precipitation method marked the highest activity showing 1-butene conversion, 79.5%, butadiene selectivity, 85.1% and yield, 67.7% after reaction for 14 h. From the result of $NH_3$-TPD, the catalytic activity is closely related to the acidity of the $BiFe_{0.65}MoP_{0.1}$-x oxide catalyst and acidity of the $BiFe_{0.65}MoP_{0.1}$ oxde catalyst prepared with co-precipitation method was higher than that of other catalysts. In addition, combined with the 1-butene TPD, the higher catalytic activity is closely related to the amount of weakly adsorbed intermediate (< $200^{\circ}C$) and the desorbing temperature of strongly adsorbed intermediates (> $200^{\circ}C$).