• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.352-359
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• 2005

This work has studied the changes of pH in both of anodic and cathodic chambers of a divided cell due to the electrolytic split of water during the ammonia decomposition to nitrogen, and has studied the continuous decomposition characteristics of ammonia in a multi-cell stacked electrolyzer. The electrolytic decomposition of ammonia was much affected by the change of pH of ammonia solution which was caused by the water split reactions. The water split reaction occurred at pH of less than 8 in the anodic chamber with producing proton ions, and occurred at pH of more than 11 in the cathodic chamber with producing hydroxyl ions. The pH of the anodic chamber using an anion exchange membrane was sustained to be higher than that using a cation exchange membrane, which resulted in the higher decomposition of ammonia in the anodic chamber. By using the electrolytic characteristics of the divided cell, a continuous electrolyzer with a self-pH adjustment function was newly devised, where a portion of the ammonia solution from a pHadjustment tank was circulated through the cathodic chambers of the electrolyzer. It enhanced the pH of the ammonia solution fed from the pH-adjustment tank into the anodic chambers of the electrolyzer, which caused a higher decomposition yield of ammonia. And then, based on the electrolyzer, a salt-free ammonia decomposition process was suggested. In that process, ammonia solution could be continuously decomposed into the environmentally-harmless nitrogen gas up to 83％, when chloride ion was added into the ammonia solution.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.5
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• pp.622-630
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• 1998

Rotating Biological Contactor (RBC) was tested for the removal of total ammonia nitrogen (TAN) by using simulated aquaculture system. RBC performance was evaluated by controlling revolution rate of disk and hydraulic residence tile (HRT). The optimum revolution rate of disk was 4 rpm, As HRT of RBC was increased, TAN removal efficiency of RBC and TAN concentration of rearing water were increased. HRT for maintaining lowest TAN concentration of rearing water was 9.5 minutes and at that condition TAN concentration of rearing tank was $1.03 g/m^3$

• Journal of Hydrogen and New Energy
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• v.34 no.6
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• pp.594-600
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• 2023

In this study, a process model and optimization design direction for a hydrogen production plant through ammonia decomposition are presented. If the reactor decomposition rate is designed to approach 100%, the amount of catalyst increases and the devices that make up the entire system also have a large design capacity. However, if the characteristics of the hydrogen regeneration process are reflected in the design of the reactor, it becomes possible to satisfy the total flow rate of fuel gas with the discharged tail gas flow rate. Analyzing the plant process simulation results, it was confirmed that when an appropriate decomposition rate is maintained in the reactor, the phenomenon of excess or shortage of fuel gas disappears. In addition, it became possible to reduce the amount of catalyst required and design the optimized capacity of the relevant processes.

• Korean Chemical Engineering Research
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• v.43 no.1
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• pp.9-15
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• 2005

In order to know the electrochemical decomposition characteristics of ammonia to nitrogen, this work has studied several experimental variables on the electrolytic ammonia decomposition. The effects of pH and chloride ion at $IrO_2$, $RuO_2$, and Pt anodes on the electrolytic decomposition of ammonia were compared, and the existence of membrane equipped in the cell and the changes of the current density, the initial ammonia concentration and so on were investigated on the decomposition. The performances of the electrode were totally in order of $RuO_2{\approx}IrO_2>Pt$ in the both of acid and alkali conditions, and the ammonia decomposition was the highest at a current density of $80mA/cm^2$, over which it decreased, because the adsorption of ammonia on the electrode surface was hindered due to the evolution of oxygen. The ammonia decomposition increased with the concentration of chloride ion in the solution. However, the increase became much dull over 10 g/l of chloride ion. The $RuO_2$ electrode among the tested electrodes generated the most OH radicals which could oxidized the ammonium ion at pH 7.

• Journal of Biosystems Engineering
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• v.23 no.1
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• pp.31-48
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• 1998

가축분뇨, 음식쓰레기 둥의 유기성 고형 폐기물의 퇴비화처리 과정의 성능 향상과 암모니아 가스 발생을 저감화 하려는 연구의 일환으로서 파이로트 규모의 원통형 회분식 분해조 및 숙성조를 설계, 제작하여 퇴비화 성능과 탈취 효과를 분석하였다. 고형퇴비화 처리에 미치는 주요요인은 초기재료의 수분, 탄질비, 수소이온농도, 발효온도 및 통기조건 등이다. 돈분에 부자재인 톱밥을 혼합하여 초기 재료의 수분, 탄질비, 수소이온농도 등을 동일한 재료로서 같은 수준에 유지하고 연속통기와 간헐통기 방식으로 퇴비화하는 동안에 분해 및 숙성단계의 부위별 발효온도의 변화, 산소흡수 및 탄산가스 배출농도의 변동, 평균통기량, 재료의 평균온도 변화, 암모니아가스 배출농도의 변화 등을 분해 및 숙성 전기간을 통해 측정하고 초기재료와 숙성재료의 주요 이화학적 성분을 분석하여 퇴비화 성능과 회비 탈취 효율을 비교하였다. 주요 연구결과는 다음과 같다. 1. 숙성과정 8일 이후의 암모니아가스 탈취효율은 연속통기법이 90%이고, 간헐통기법이 70%였으며, 분해 및 숙성과정의 발효온도, 탄산가스 발생, 암모니아가스 배출농도 및 숙성회비의 성분 둥의 결과로서 판단할 때 에 퇴비 화 소요기 간은 6주간이었다. 2. 탄산가스 배출농도 변화로서 간헐통기 퇴비화 방식은 연속통기법에 비하여 분해과정이 7일 정도 빠르고, 숙성과정이 10일 정도 단축되었으며 암모니아가스 농도도 적게 나타나고 있었다. 3. 퇴비화 분해과정이 지난 후 숙성과정 도입단계에서 퇴비재료의 혼합 교반에 따른 재료의 고온상승으로 인한 암모니아가스의 고농도화 현상의 억제대책이 필요하다고 판단되었다.

• Elastomers and Composites
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• v.34 no.3
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• pp.239-246
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• 1999

Side wall samples from a used automotive tire were subjected to subcritical and supercritical decomposition and extraction with three solvents, water, 28% ammonia solution and ammonia. For 6mm cube samples the rate of supercritical extraction with water followed a first-order kinetics with an activation energy of 140 kJ/mol. Solvent power of 28% ammonia so lotion at supercritical condition was found to be higher than supercritical water at initial extraction as pressure decreased. These phenomena were considered to be an effect of ammonia involved in water.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2001.11a
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• pp.77-79
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• 2001

본 연구에서는 전기분해에 의한 양식장 배출수중의 유기물질 및 암모니아를 전류밀도, 전극간격에 따른 제거 특성을 살펴보았다. 전극간격 및 전류밀도에 따른 제거효율은 전극간격이 가까울수록, 전류밀도가 클수록 제거효율은 증가하였다 유기물질은 107.5A/$m^2$의 전류밀도에서 반응기 체류시간 8분동안 98.5%, 암모니아는 전류밀도를 107.15A/$m^2$로 유지하고, 간격을 변화시키면서 반응기 체류시간 120sec동안 암모니아의 제거율을 보면 92.6%의 제거효율을 나타내었다.

• Journal of the Korean Chemical Society
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• v.26 no.2
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• pp.88-94
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• 1982

The concentrations of gaseous ammonia and particulate ammonium emitted from a urea plan were measured, and the conversion rate of ammonia to ammonium was estimated. The conversion of ammonia to ammonium has two stages with transport time in the atmosphere. In the initial 15min the conversion rate was 3.2% min$^{-1}$, and thereafter 0.26% min$^{-1}$. The high conversion rate of ammonia to ammonium at the initial period of it's transport might be due to the dissolution of ammonia into water droplets formed by the decrease in temperature of the stack effluent. The concentration of ammonium is further increased by the decomposition of urea in alkaline droplet formed. Half-lives of ammonia gas at initial and latter slag were 16 min and 192 min respectively. No correlation of particulate ammonium concentration to temperature, relative humidity, and concentrations of sulfur dioxide, nitrogen oxides and airborne particulate matter were found in this field measurement.

• Korean Chemical Engineering Research
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• v.53 no.4
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• pp.417-424
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• 2015

In this study, the pretreatment of Helianthus tuberosus residue had been performed. The two-stage pretreatment on flow-through process were applied in the interests of increase of sugar production yield on enzymatic saccharification. The delignification by aqueous ammonia and the fractionation of hemicellulose by sulfuric acid solution as pretreatment solution were confirmed for effects of enzymatic saccharification. Two-stage pretreatment process was performed using aqueous ammonia and sulfuric acid. The first step was performed with aqueous ammonia for 40 min at $163.2^{\circ}C$ and the second step was performed with sulfuric acid solution for 20 min at $169.7^{\circ}C$. And then, the first step was performed with sulfuric acid solution and the second step was pretreated with aqueous ammonia. At this time, the glucose production was 30.7 g and the glucose yield was 72.4% in the first step process with aqueous ammonia. And, the glucose production was 20.9 g and the glucose yield was 49.3% in the first step process with sulfuric acid solution.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.112.1-112.1
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• 2011

쌀을 주식으로 하는 우리나라의 여건상 연간 추정치로 싸라기 약 12만톤, 미강 약 49만톤, 왕겨 약 79만톤의 벼 도정 부산물이 발생하고 있다. 본 연구에서는 벼 도정 부산물 중 비식량 자원인 왕겨를 대상으로 고효율 효소 당화를 위한 바이오매스 전처리 방법을 탐색하였다. 왕겨 원시료의 초기 조성은 셀룰로스 34.5%, 헤미셀룰로스 20.5%, 리그닌 25.3%, 회분 14.6%로 나타났는데, 억새 등 초본계 바이오매스와 비교하여 특이하게 높은 성분은 회분으로 이는 벼에 대한 규산질 비료의 시용에서 기인한 것이다. 바이오매스 전처리에 많이 사용되는 암모니아, 희황산 용매와 규산염에 침식성을 가지는 가성소다 용매를 이용하여 각 용매별 단독 및 알칼리-산 복합 처리 하였을 때 효소 가수분해 효율, 고상시료 성분변화 등을 상호 비교하였다. 예비실험을 통하여 암모니아 처리조건은 15%(w/w) $150^{\circ}C$ 20분, 가성소다 처리조건은 1.5%(w/w) $150^{\circ}C$ 20분, 희황산 처리조건은 1.0%(w/w) $150^{\circ}C$ 10분으로 설정하였다. 암모니아 단독, 희황산 단독, 암모니아-희황산 복합 처리 시료의 효소 가수분해 효율은 각각 37.8%, 39.1%, 42.8%로 약 40%선에서 큰 차이가 없었다. 반면 가성소다 단독, 가성소다-희황산 복합 처리시료의 효소 가수분해 효율은 각각 62.7%, 82.8%로 나타나 앞선 3가지 처리방법 대비 50%, 100%에 가까운 효소 가수분해 효율 향상을 보였다. 이 때 전처리 고상시료의 성분 변화를 살펴보면 회분 함량에서 큰 차이를 보였는데 암모니아 단독, 가성소다 단독, 희황산 단독, 암모니아-희황산 복합, 가성소다-희황산 복합 처리에서 각각 47.8%, 77.1%, 43.5%, 55.8%, 94.7%의 회분 성분 기각률(rejection rate)을 나타냈다. 이는 왕겨 효소 가수분해 효율의 최대 저해요인이 회분임을 추정할 수 있다. 왕겨 전처리 알칼리 용매는 암모니아보다 가성소다가 더 효과적이었고 희황산 복합 처리시 그 효과가 크게 상승하였다. 따라서 규산염(회분) 함량이 높은 바이오매스는 고온 고압 조건에서 가성소다 용액으로 처리한 후 그 고상분을 희황산 용액으로 복합 처리하는 시스템이 효소 당화 증진에 매우 유리함을 확인하였다.