• Cement
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• s.153
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• pp.50-54
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• 2000

• Clean Technology
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• v.26 no.4
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• pp.304-310
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• 2020

In order to apply a photocatalyst (TiO2) to various building materials, TiO2-mayenite was prepared in this study. The TiO2 was synthesized using the sol-gel method by fixing titanium isopropoxide (TTIP) and urea at a ratio of 1 : 1. Later, they were calcined in a temperature range of 400-700 ℃ to analyze the properties according to temperature. BET, TGA, and XRD were used to analyze the physical and chemical properties of TiO2. The nitrogen oxide removal test was confirmed by measuring the change in the concentration of NO for 1 h according to KS L ISO 22197-1. The prepared TiO2 samples exhibited an anatase crystal structure below 600 ℃, and TiO2 (urea)-400 showed the highest nitrogen oxide removal rate at 2.35 µmol h-1. TiO2-mayenite was prepared using two methods: spraying TiO2 dispersion solution (s/s) and sol-gel solution (g/s). Through BET and XRD analysis, it was found that 5-TiO2 (g/s) prepared by spraying a sol-gel solution has maintained its crystallinity even after heat treatment. Also, 5-TiO2 (g/s)-500 showed the highest removal rate of 0.55 µmol h-1 in the nitrogen oxide removal test. To prepare TiO2-mayenite, it was confirmed that mayenite should be blended with TiO2 in a sol-gel state to maintain the crystal structure and exhibit a high nitrogen oxide removal rate.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.143-144
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• 2001

질소산화물(NOx) 제거기술 중, 선택적촉매환원(Selective Catalytic Reduciton: SCR)공정은 배기가스 중에 포함되어 있는 질소산화물을 암모니아와 촉매상에서 반응시켜 무해한 질소와 물로 전환하는 기술로 높은 탈질율 및 안정적인 기술로 인하여 상업적으로 널리 이용되고 있다(Bosch, 1988). 귀금속촉매, Cu/Zeolite 촉매 및 V$_2$O$_{5}$/TiO$_2$ 등 다양한 촉매들이 SCR 공정에 적용되는데 V$_2$O$_{5}$/TiO$_2$ 촉매가 높은 활성과 황 등 피독 물질에 대한 우수한 내구성으로 인하여 가장 효과적인 촉매로 알려져있다(Heck, 1999). (중략)

• Environmental engineer
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• v.19 s.207
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• pp.92-95
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• 2003

• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.668-675
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• 2019

Fine dust in air pollutants is recognized as one of the most serious social environmental problems. Most of the NOx is generated in a combustion process such as that of a coal-fired power plant, and therefore efficient elimination of the NOx from the coal-fired power plants is needed. This study investigates the removal efficiency of using $TiO_2$, a photocatalyst, to remove NOx by Selective Catalytic Reduction (SCR). To evaluate the NOx removal efficiency, $TiO_2$ catalyst and phosphate binder were mixed on the surface of the $Al_2O_3$ substrate with the exothermic agent, and the substrate was heat-treated. The NOx removal efficiency of the catalysts was evaluated according to the temperature, and XRD, SEM, TG-DTA and BET analyzes were performed to investigate the physicochemical properties of the catalysts. NOx removal efficiency was 58.7%~65.9% at 20min, 63.7~66.0% at 30min with temperature change according to time($250^{\circ}C{\sim}500^{\circ}C$). The $TiO_2$ used in the SCR for NOx removal is judged to have the most efficient removal efficiency at $300^{\circ}C$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3578-3582
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• 2010

The nitrogen oxidized substance(NOx) from cars in city is one of serious air-polution problems. In advanced country, the powder or the liquid photocatalystic for asphalt pavement and noise barrier have been used to reduce the air-polution. In this paper, the effect of photocatalystic on asphalt pavement has been evaluated, especially for UV optical science reactions analyzed NOx purification efficiencies of the automobile waste gas. Judging from the limited lab-scale test, the use of the powder or the liquid photocatalystic is one of alternatives to reduce the NOx from automobile.

• Applied Chemistry for Engineering
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• v.21 no.3
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• pp.243-251
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• 2010

Nitrogen oxides (NOx) in combustion flue gas are currently mitigated by chemical processes such as catalytic reduction, absorption and adsorption. However, development of environmentally sustainable biological processes is necessary in the near future. In this paper, the up-to-dated R&D trend of biological methodologies regarding NOx removal was reviewed, and their advantages and disadvantages were discussed. The principles and applications of bacterial system including nitrification and denitrification and photosynthetic microalgae system were compared. In order to enhance biological treatment rate and performance, the insoluble nitric oxide (NO) should be first absorbed using a proper solubilization agent, and then microbial degradation or fixation is to be followed. The use of microalgal system has a good prospect because it can fix $CO_2$ and NOx simultaneously and requires no additional carbon for energy source.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.120-127
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• 2022

Nitrogen oxide(NOx) is a major cause of air pollution, exists in the form of nitrogen monoxide and nitrogen dioxide, and is harmful to the human body. Recently, a number of studies to reduce NOx in the atmosphere have been conducted, and these efforts have been the same in the field of construction materials. It is known that NOx can be efficiently removed by using a photocatalytic reaction. In this study, the NOx removal performance of the foam composite using activated carbon(AC) and titanium dioxide(TiO₂) was investigated. AC was used to enhance the photocatalytic reaction of TiO₂ by increasing the internal specific surface area of the foam composite. In this study, foam composites were prepared using the substitution rate of AC as the main variable. The NOx removal performance of specimen was evaluated according to the test method presented in ISO-22197-1. The specific surface area of the foam composite showed a tendency to increase according to the AC content, but decreased at 15% or more. Also, when the AC substitution rate was 15%, the NOx removal efficiency was the highest.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.2
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• pp.163-170
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• 2022

The present study investigates NO_x-removal and sound-absorption performances of photocatalytic porous concrete prepared by various TiO₂ application methods. Photocatalytic porous concrete samples were prepared by one of the following: 1) mechanically mixing TiO₂ during casting; 2) mixing bottom ash aggregate pretreated with TiO₂ during casting; and 3) spraying TiO₂ solution to the normally fabricated porous concrete. The test results indicated that the mechanical mixing of TiO₂ decreased the compressive strength as the added TiO₂ content increased. The use of pretreated bottom ash aggregate reduced the porosity, yet the compressive strength of the concrete was similar to that measured from the former method. Porous concrete samples sprayed with the TiO₂ solution exhibited enhanced compressive strength, while the porosity was analogous to those measured from other methods. The NO_x-removal performance was the highest in the samples sprayed with the TiO₂ solution, followed by the samples using pretreated bottom ash aggregate and mechanically mixed TiO₂. The samples with mechanically mixed TiO₂ identified a relationship between soundabsorption performance and porosity. However, no particular tendency was observable in the samples with other TiO₂ application methods.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.204-206
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• 2014

석탄 화력발전소에는 연소가스의 질소산화물(NOx) 저감을 위한 SCR(selective catalytic reduction)설비가 운전되고 있으며, SCR은 환원제인 암모니아($NH_3$)를 이용하여 연소가스 내에 질소산화물을 물과 질소로 분해하는 역할을 한다. 그러나, 연소가스 중의 일부 삼산화황($SO_3$)과 미반응 암모니아가 결합하여 황산암모늄염(Ammonium bisulfate; $NH_4HSO_4$)을 생성하며, 이는 후단 APH(air preheater)의 열소자에 점착된 후 분진들과 함께 성장하여 막힘을 야기한다. 막힘이 발생된 APH는 연소가스의 흐름을 방해하기 때문에 차압을 증가시키며, 이는 발전효율의 감소뿐만 아니라 급전정지를 초래한다. 이를 해결하기 위하여 $CO_2$ 드라이아이스 세정 방법을 적용하였으며, pilot-scale plant에서 실험을 수행하였다. 또한, 드라이아이스 공정변수인 분사압력과 분사시간을 제어하여 pilot-scale plant의 APH 열소자 표면에 생성되어있는 오염물질들의 제거효율을 관찰한 결과 95 %의 높은 제거효율을 보였다.