• Journal of Sensor Science and Technology
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• v.32 no.2
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• pp.67-74
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• 2023

A microfluidic paper-based analytical device (µPAD) is proposed for the selective detection of ammonia in water by using the modified Berthelot reagent and a fluidic channel consisting of hollow paper. The modified Berthelot reagents were uniformly dispersed in cyclohexane and then immobilized in a detection zone of the µPAD. The loading position of the reagents and the type of a sample flow channel were optimized to achieve a sensitive ammonia detection within a short analytical time. The NH₃ µPAD exhibits a linear colorimetric response to the concentration of ammonia dissolved in water in the range of 1-100 mg L^-1, and its limit-of-detection is 1.75 mg L^-1. In addition, the colorimetric response was not influenced by the addition of 100 mg L^-1 nitrogen containing compounds (sodium nitrate, sodium nitrite, uric acid, hydroxylamine, butylamine, diethylamine) or inorganic salts (NaCl, Na₂HPO₄), presenting the enough selectivity in the detection of water-dissolved ammonia against possible interferents.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.4
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• pp.387-394
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• 2011

A study on the removal of sulfur dioxide and nitrogen oxide was carried out using a non-thermal nano-pulse corona discharger at different gas temperatures. Pulse voltage with a high voltage of 50 kV, a pulse rising time of about 100 ns, a full width at half maximum of about 500 ns and a frequency of 1 kHz was applied to a wire-cylinder corona reactor. Ammonia and propylene gases were added into the corona reactor as additives with a static mixer. Ammonia addition had less effect on $SO_2$ reduction at the higher temperature because of the retardation of ammonium sulfate formation. However, propylene addition enhanced NO reduction at higher temperature due to increased gas mixture. $SO_2$ was further removed at the mixed $SO_2$ and NO gas due to increased $NO_2$ by the conversion of NO. The addition of ammonia and propylene gases was more highly dominant for the removal of sulfur dioxide compared to the sole pulse corona without the additives. However, the specific energy density per unit concentration of pulse corona as well as propylene additive was an important factor to remove NO gas. Therefore, the specific energy density per unit concentration of 0.04 Wh/($m^3{\cdot}ppm$) was necessary for the NO removal of more than 80% with the concentration ratio of 2.0 for propylene and NO. Hydrogen peroxide was another alternative additive to remove both $SO_2$ and NO in the nano-pulse corona discharger.

• Applied Chemistry for Engineering
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• v.34 no.5
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• pp.541-547
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• 2023

The effect of temperature and influent alkalinity/ammonia (K/A) ratio on the start-up of the partial nitrification (PN) process for an activated sludge-based domestic wastewater treatment was studied. Two different sequence batch reactors (SBR) were operated at 26 ℃ and 32 ℃. The relationship between temperature and the concentration of free ammonia (FA) and free acid nitrite (FNA) was investigated. A stable PN process was achieved in the 32 ℃ reactor when the influent ammonium concentration was lower than 150 mg-N/L. In contrast, the PN process in the 26 ℃ reactor had a higher nitrite accumulation rate (NAR) and ammonium removal efficiency (ARE) when the influent ammonia concentration was increased to more than 150 mg-N/L. Then three different ranges of the K/A ratio were applied to an SBR reactor. In the K/A range of 2.48~1.65, the SBR reactor achieved the highest NAR ratio (75.78%). This ratio helps to achieve the appropriate level of alkalinity to maintain a stable pH and provide a sufficient amount of inorganic carbon source for the activity of microorganisms. At the same time, FA and FNA values also reached the threshold to inhibit nitrite-oxidizing bacteria (NOB) without a significant effect on ammonia-oxidizing bacteria (AOB). Results showed that the control of temperature and K/A ratio during the start-up period may be important in establishing a stable and steady PN process for the treatment of domestic wastewater.

• Journal of Environmental Science International
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• v.21 no.1
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• pp.49-55
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• 2012

In this study, the characteristic of offensive major odorous compound from the Bon-San industrial complex in Gimhae were determined by analytical methods of Gas Chromatography, High Performance Liquid Chromatography and UV/VIS Spectrophotometer. The kind of major odorous compounds examined acetaldehyde, sulfur compounds, ammonia and styrene. The concentration of all odorous compounds at 3 sampling points of industrial complex were lower than those of regulation standard levels of the industrial complex in Korea. The mean concentration of hydrogen sulfide was 0.0235 ppm at sampling point 2, it was higher than other sampling point. Complex odors was lower than regulation standard levels of the industrial complex in Korea.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.6
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• pp.729-738
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• 2004

Seasonal variation of major inorganic ions in the greater Seoul area was estimated using a photochemical box model and a gas/aerosol equilibrium model with emphasis on semi -volatile nitrate. Pollutant emission was determined by season by comparing the predicted concentration with the measurement one obtained for a year from the late 1996. The results showed that particulate nitrate was the highest in summer but about 40% of total nitrate was present in the gas phase. This was due to volatilization at high temperature since ammonia was sufficient to neutralize all nitrate regardless of season. As relative humidity in summer was higher than the deliquescence point, particulate ion concentration with water was two times higher than that in other season. So called ‘NOx disbenefit’ indicating increase in particulate ion concentration with decrease in NOx emission was evident especially in winter.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.10
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• pp.828-834
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• 2003

A diffusion absorption refrigerator is a heat-generated refrigeration system. It uses a three-component working fluid consisting of the refrigerant (ammonia), the absorbent (water) and the auxiliary gas (hydrogen or helium). In this study, experimental investigations have been carried out to examine the effects of charging conditions of working fluids on the evaporating temperature for diffusion absorption refrigerator. Experimental parameters considered in the present experiments are charging concentration, solution charge and system pressure determined by auxiliary gas charged. As a result, in the charging condition of 35% of concentration and 20 kg$_{f}$cm$^2$ of system pressure, the system has the lowest evaporating temperature. It was found that there exists a minimum value of solution charge for the operation of diffusion absorption refrigerator.r.

• Journal of Animal Science and Technology
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• v.48 no.1
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• pp.123-130
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• 2006

Principal aim of this study is to suggest the statistical equation model which can predict an amount of ammonia emission according to the degree of compost maturity during composting livestock manure. Composting process was classified with intial, midterm and final phase based on germination index of compost samples. Total Kjeldahl nitrogen(TKN) and organic matter(OM) were selected as the independent variables available to contribute to ammonia emission from composting pile. Ammonia concentration measured in the samples taken at the intial phase was about 10ppm, sharply increased to 50ppm at the midterm phase, and gradually decreased to about 10ppm. The contents of Total Kjeldahl nitrogen and organic matter through whole composting period were ranged from 0.6 to 1.2% and from 30 to 40%, respectively, were reduced slightly at the midterm phase, but generally showed no constant fluctuation pattern. In estimating ammonia emission with application of the statistical equation model, the coefficients of independent variables at the midterm phase when an average concentration of ammonia was highest showed a relatively high values whereas those at the initial phase when an that of ammonia was lowest indicated a relatively low values. However, no statistical significance was found in the coefficients of independent variables and the equation model. Additionally, the further research, which can include the considerable analysis data with more samples taken than this study, is needed in order to suggest the statistically significant equation model available to predict ammonia emission during composting process.

• 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.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.590-593
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• 2001

The effect of salinity on the nitrification efficiency of the nitrifier consortium was evaluated for the nitrification of saline wastewater. The nitrifier consortium, which was the activated sludge acclimated with ammonium as the only energy source, was used as the nitrifier for the salt acclimation. Airlift reactors for the nitrification of ammonia with increasing concentration in saline synthetic wastewater (35 g/I NaCD, and synthetic wastewater without salt as a control, were continuously operated with the nitrifier consortium for 43 days. The ammonia removal rate was about 23g ammonia-N/$m^3$/day in both the absence and presence of the salt. An accumulation of nitrite was observed in the saline nitrification reactor at an early period. However, the nitrite decreased to less than 1 mg/l after 39 days of operation. The salinity increased the acclimation time of the nitrifier consortium to obtain a stable marine nitrification system. However, the salt acclimated system showed the efficient removal of ammonia which was same as that without salt.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.2039-2044
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• 2011

A semi-continuous and automated method for quantifying atmospheric ammonia at the parts per billion level has been developed. The instrument consists of a high efficiency diffusion scrubber, an electrolytic on-line anion exchange device, and a conductivity detector. Water soluble gases in sampled air diffuse through the porous membrane and are absorbed in an absorbing solution. Interferences are eliminated by using an anion exchange devises. The electrical conductivity of the solution is measured without chromatographic separation. The collection efficiency was over 99%. Over the 0-200 ppbv concentration range, the calibration was linear with $r^2$ = 0.99. The lower limit of detection was 0.09 ppbv. A parallel analysis of Seoul air over several days using this method and a diffusion scrubber coupled to an ion chromatography system showed acceptable agreement, $r^2$ = 0.940 (n = 686). This method can be applied for ambient air monitoring of ammonia.