• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.53-56
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• 2015

In this study, investigated the synthesis method of p-Phenylenediamine (PPD) by amination of p-Diiodobenzene (PDIB) under supercritical ammonia and CuI catalyst conditions. We examined the effects of various process variables (e.g., reaction temperature, pressure, amount of ammonia inserted, amount of catalyst inserted, and reaction time) on the production yield of PPD by analyzing the Gas Chromatography (GC). The experimental results demonstrated that PPD was not produced under non-catalyst conditions, and PPD production yield increased with increasing temperature, pressure, amount of catalyst inserted, and reaction time. However, for the reaction temperature case, it was found that $200^{\circ}C$ was the optimal temperature, because thermal degradation of PPD occurred above $250^{\circ}C$. In addition, we confirmed the structure of PPD and the bonding characteristics of the amine group via FT-IR and H-NMR analysis.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.1
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• pp.1-6
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• 2012

Down Stream K River has high COD (4-10 mg/L) and high $NH_3$-N concentration (3.5 mg/L during winter period). Although $NH_3$-N itself is not reported harmful at this level, it must be removed to meet drinking water standard (0.5 mg/L). We constructed a pilot plant modifying the processes of conventional drinking water facilities. Prechlorination and powdered activated carbon (PAC) dechlorination was adopted prior to a flocculation tank to remove ammonia and prevent disinfection byproducts (DBPs) formation. Also, GAC processes was included after sand filter to remove residual DOC. This pilot having a capacity of 36 ton/day was operated for one year. The GAC processes were successful to remove ammonia and many organic pollutants (DOC, MBAS, UV-254 nm absorbance, etc). Influent DOC concentrations were very high as 3~6 mg/L throughout the plant operation. It was impossible to achieve 1.0 mg/L effluent DOC, indicating that bed depth (2 m) should be increased to achieve more strict DOC quality standards. When $Cl_2$ dose was well controlled ($Cl_2/NH_3$-N ratio 10~11 on a weight basis), $NH_3$-N removal was 98% and THMs was very low possibly due to low free residual chlorine and PAC dechlorination.

• Clean Technology
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• v.7 no.4
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• pp.273-280
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• 2001

An absorber is a major component in the absorption refrigeration systems and its performance greatly affects the overall system performance. In this study, experimental analyses on heat transfer characteristics for removal of absorption heat in ammonia-water bubble mode absorber were performed. Heat transfer coefficients were estimated as the variations of input gas flow rate, solution flow rate, temperature, concentration, absorber diameter and height, and input flow direction. The increase of gas and solution flow rate affects positively in heat transfer. However, the increase of solution temperature and concentration affects negatively. Moreover, under the same Reynolds Numbers, countercurrent flow is superior to cocurrent flow in heat transfer performance. In addition, from these experimental data, empirical correlations which can explain easily the characteristics of heat transfer are derived.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.8
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• pp.761-766
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• 2010

This study was aimed to propose La(III)-zeolite composite which can effectively and simultaneously remove ammonia and phosphate in confined water bodies such as lakes and ponds. The optimum ratio of La(III):zeolite for the simultaneous removal of ammonia and phosphate was 0.0048 La(III) g:1 zeolite g. The drying temperature of La(III)-zeolite composite severely affected phosphate adsorption showing optimum condition at room temperature. It was revealed that the optimum dosage of La(III)-zeolite composite was 4.052 g/L at adsorption time of 90 min. The presence of alkalinity in aqueous solution brought positive effect on phosphate adsorption. Detachment of La(III) from La(III)-zeolite composite, which was dried at room temperature, was not observed in aquous solution. It indicates that La(III)-zeolite composite could effectively block phosphate released from sediment.

• Korean Journal of Environmental Agriculture
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• v.20 no.4
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• pp.225-231
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• 2001

This study was conducted to find out the optimal aeration rates for minimizing odor emission and for increasing biological activities during composting of livestock manure in the enclosed bench-scale reactor system. It was treated with the mixture of poultry manure and sawdust controlled the initial water content of 60%, then aerated continuously at four different aeration rates (0.1, 0.2, 0.4 and 0.6 L/min/kg dry-solids). The average emitted concentration of ammonia in 0.6 L/min/kg dry-solids during composting reached the level of 40% in comparison with that of 0.2 L/min/kg dry-solids. In cases of sulfur compounds such as hydrogen sulfide, methylmercaptan and ethylmercaptan, their concentrations decreased with increasing aeration rates and the emission time was shortened. But they didn't detect in the treatment of 0.6 L/min/kg dry-solids. The biological activity for composting showed a trend of increasing as aeration rates increased. The treatment of 0.6 L/min/kg dry-solids gave the highest biological activity and the best compost quality.

• KSBB Journal
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• v.13 no.3
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• pp.238-243
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• 1998

Nitrifier consortium immobilized in Ca and Ba-alginate beads were packed into two bioreactors and the performances of bioreactors were evaluated for the removal of ammonia nitrogen from synthetic aquaculture water. The total ammonia nitrogen (TAN) concentration of the influent was continually kept about 2g TAN/㎥. At the HRT of 0.6hr, ammonia nitrogen removal rate of two bioreactors were about 52.6 and 51.0g TAN/$\textrm{m}^3$/day, respectively. At the respect of ammonia nitrogen removal, two bioreactor showed the similar abilities. The second trial with nitrifier consortium immobilized in Ca-alginate bead was carried out to evaluate the ammonia nitrogen removal rate for 35 days. The highest ammonia nitrogen removal rate was 82g TAN/$\textrm{m}^3$ when HRT was about 0.3hr.

• Journal of Wetlands Research
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• v.16 no.2
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• pp.275-280
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• 2014

Because ammonia in water body can cause water pollution as a result of generating ammonium ion, it is of importance in the management of water quality. This work performed to analyze the ammonium ion by measuring the color band length on the basis of modifying the indophenol method. When 1-naphthol was employed as a coloring agent, the maximum absorbance was shown near 720nm, where the proper injection was in the range of 0.5-1.5ml. About 80% of absorbance was observed after the color development was made within the 20 minutes. In the manufacturing of coloring agent, the proper concentration of NaOH was 1.5-2.5M, and the effect of pH on the color development is negligible. In addition, the color development was effectively in the region of room temperature.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.196-200
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• 2005

A theoretical model for the calculation of chemical equilibrium composition of propellant combustion product is briefly presented for the performance analysis of monopropellant hydrazine rocket engine. Analysis result is compared to that of test and evaluation of 1-lbf class thruster and is scrutinized primarily from the view point of ammonia dissociation fraction. Chemical equilibrium composition and average molecular weight is additionally depicted according to the variation of propellant inlet pressures and the varying nozzle area ratio. The theoretical analysis is tried as a way of derivation of design parameters for mid- and large-thrust class of monopropellant rocket engines.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.12
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• pp.811-820
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• 2007

A Study on the optimal design of the AIG(Ammonia Injection Grid) to improve the performance of DeNOx facilities in the HRSG(Heat Recovery Steam Generator) was performed using the CFD analysis. On the basis of the flow analysis results in the case that the AIG in the HRSG was not installed, the numerical analyses according to the positions of AIG, injection angles of nozzle and the control of ammonia injection quantity were carried out. The standard deviation according to factors was calculated for quantitative comparison. As the results, the AIG in the HRSG should be installed in the position that the uniform flow field shows through the exact flow analysis in the previous of the AIG design and installation. In the case the AIG has already been installed and non uniform flow distribution shows, it is recommended that flow correction device or KoNOx catalyst should be used. Otherwise, the control of ammonia injection angle or the ammonia injection quantity using the velocity profile analysis is demanded to accomplish the optimal performance.

• 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.