• Korean Journal of Environmental Agriculture
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• v.17 no.3
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• pp.200-204
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• 1998

Physical and chemical properties of artificial soil produced by firing process were analyzed and compared with normal dry field soil and soil quality standards. Material used for production was water and wastewater treatment sludge, chabizite, and lime. The mixed material was thermally treated in the firing kiln at about $300^{\circ}C$ and $1,000^{\circ}C$, respectively, as per designed process. General properties of the artificial soil were classified as sand by unified soil classification method and similar to the dry-field soil, and even soil conditioning effect were expected when it is mixed properly with normal soil. The artificial soil is high in pH and permeability compared to the dry-field soil. Heavy metal concentrations of the artificial soil met the soil quality standards for the farmland. Overall, the artificial soil was thought to be an appropriate soil which can be returned safely to the nature without significant adverse effect. The cost for the artificial soil production process needs to be lowered for practical application as a sludge treatment, therefore, commercializing of the artificial soil is under review.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.594-603
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• 2018

The effects of operating conditions such as benzene concentration, nitrogen flow rate, steam flow rate, and bed temperature on TSA process were experimentally investigated as a potential VOC removal technology using two kinds of beds packed with activated carbon and zeolite 13X. The TSA cycle studied was composed of the adsorption step, steam desorption step, and drying and cooling step. At 2% benzene concentration, the total adsorption amounts of zeolite 13X and activated carbon were 4.44 g and 3.65 g, respectively. Since the zeolite 13X has a larger packing density than that of the activated carbon, the larger benzene amount could be adsorbed in a single cycle. Increasing the water vapor flow rate to 75 g/hr at 2% benzene concentration reduced the desorption time from 1 hr to a maximum of 33 min. If the desorption time is shortened, the drying and cooling step period can be relatively increased. Accordingly, the steam removal and bed cooling could be sufficiently performed. The desorption amounts increased with the increase of the bed temperature. However, the energy consumption increased while the desorption amount was almost constant above $150^{\circ}C$. In the continuous cycle process, when the amount of remained benzene at the completion of the regeneration step increased, it might cause a decrease in the working capacity of the adsorbent. The continuous cycle process experiment for zeolite 13X showed that the amount of remained benzene at the end of regeneration step maintained a constant value after the fourth cycle.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1093-1097
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• 2006

하천수계는 여러 인자들의 상호작용을 통하여 변화하게 되며, 하천 자정능력에 관한 연구는 이를 중심으로 진행되어 왔다. 여러 환경 요인 중 하상재료는 하천의 조도와 수생태계의 특성을 변화시키게 되며, 유입수의 성상에 따라 수저퇴적물이 쌓이거나, 생물막이 형성되는 매개체 역할을 하게 된다. 특히, 하천의 폭이 좁고 수심이 얕은 개울에서는 하상 퇴적물이 수질에 기여하는 영향이 큰 것으로 알려져 있다. 국내하천의 경우 하상재료가 주로 모래와 자갈이 주를 이루고 있으며, 수심이 낮아 빛의 투과성이 양호하여 부착조류의 증식 및 하상재료(모래 및 자갈 등)를 기질로 한 생물막 형성 등 하상재료는 하천환경의 변화 및 수질변화가 일어나는데 상당한 기여를 하는 것으로 보고되고 있다. 본 연구에서는 하천의 하상재료가 설치된 수로를 이용하여 이화학적요소를 조사, 분석함으로써 하상재료를 통한 수질변화 특성을 비교.검토 하였다. 그 결과 하상재료의 입경이 클수록 DO 변화가 더 큰 폭으로 증가 하였으며, 수위와 유속의 경우 수위가 낮으면서 유속이 적정수준일 경우 DO 증가가 나타나는 것으로 관측되었다. 하천수가 수로에 의해 순환되면서 유기물 저감속도의 측정결과 초기 흡착, 침전 등의 물리적 작용이 부착조류 증식 등의 생물학적 작용보다 우선되면서 입자성 유기탄소(POC)의 제거속도가 용존성 유기탄소(DOC) 의 경우보다 더 빠르고 우선되는 것으로 조사되었다. 영양염류의 경우 부착성조류에 의한 질소 제거능은 실제 질산화작용은 활발히 이루어졌으나 탈질작용에 의한 총질소의 제거는 미비한 것으로 나타났으며, 총인은 입자성유기탄소가 제거되는 것과 유사한 경향을 나타내 제거 기작이 대부분 흡착, 침전에 의한 물리적 자정 작용에 기인한 것으로 조사되었다. 또한 하상재료 입경 변화에 따른 수질변화 특성은 기질(하상재료)의 입경이 작을수록 오염물질의 분해능이 큰 것으로 나타났다. 이와 같이 여러 하천환경 요인 중 하상재료에 의한 하천환경의 다양한 변화는 수질변화 및 자정능력에 큰 영향을 미치게 된다.

• Clean Technology
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• v.16 no.2
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• pp.132-139
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• 2010

The Cu-Mn mixed oxide catalysts with different molar ratios of Cu/(Cu+Mn) prepared by co-precipitation method have been investigated in CO oxidation at $30^{\circ}C$. The catalysts used in this study were characterized by X-ray Diffraction (XRD), $N_2$ sorption, X-ray photoelectron spectroscopy (XPS), and $H_2$-temperature programmed reduction $(H_2-TPR)$ to correlate with catalytic activities in CO oxidation. The $N_2$ adsorption-desorption isotherms of Cu-Mn mixed oxide catalysts showed a type 4 having pore range of 7-20 nm and BET surface area was increased from 17 to $205\;m^2{\cdot}g^{-1}$ with increasing of Mn content. The XPS analysis showed the surface oxidation state of Cu and Mn represented $Cu^{2+}$and the mixture of $Mn^{3+}$ and $Mn^{4+}$, respectively. Among the catalysts studied here, Cu/(Cu+Mn) = 0.5 catalyst showed the highest activity at $30^{\circ}C$ in CO oxidation and the catalytic activity showed a typical volcano-shape curve with respect to Cu/(Cu+Mn) molar ratios. The water vapor showed a prohibiting effect on the efficiency of the catalyst which is due to the competitive adsorption of carbon monoxide on the active sites of catalyst surface and finally the formation of hydroxyl group with active metals.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.2
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• pp.53-58
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• 1999

This study was carried out evaluate to identify water quality and contamination characteristics of the shallow groundwater. and their seasonal variation in the rual area of the Yongin city. Groundwater sample were collected two times (in April and September) from a total of 19 well for domestic water supply. and surface-water samples from six locations. For cations, Ca and Mg predominated. In anion competition. the influence of Cl was obvious in the april samples. However. HCO$_3$ was a major component in the september samples. Electric conductivities and the concentrations of NO$_3$-N in groundwater samples significantly decreased from the april samples to the september samples This indicates a significant seasonal variation in the shallow groundwater composition. When the shallow aquifer is connected to the surface water. then metals sorbed on the stream sediments could occur at nearby wells through the induced recharge. Contaminants at ground surface appeared to be transported to the groundwater system infiltration during the spring melt.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.739-744
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• 2011

Activated carbon SCR(CSCR) catalyst that is used to remove $NO_x$ in exhaust gas including boron discharged from the production process of liquid crystal display(LCD) shows deactivation when boron is deposited to block the pores within the catalyst or to cover its active sites. The spent carbon catalyst is regenerated by washing with various surfactants, drying and calcination. For comparison of the physical and chemical properties before and after the regeneration with the variables, type of surfactants and calcination condition, element analysis by ICP, $N_{2}$ adsorption were conducted. $DeNO_{x}$ in SCR with $NH_3$ was carried out in a fixed bed reactor at $120^{\circ}C$. The activated carbon catalyst regenerated through washing with a non-ionic surfactant in $H_{2}O$ at $90^{\circ}C$ and calcination under $N_{2}$ gas at $550^{\circ}C$ shows similar level of surface area and $NO_x$ removal efficiency with those of fresh catalyst.

• Membrane Journal
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• v.19 no.2
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• pp.136-144
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• 2009

In this study, sodium dedocyl sulfate (SDS), which was anionic surfactant, was added for forming micelles to remove ferrous ions that could be contained with a small amount in industrial water. Then aggregates were formed by adsorption or binding of ferrous ions on the surface of micelles, and then rejected by ceramic membranes to remove ferrous ions. Ferrous concentration was fixed at 1mM and SDS was changed as $0{\sim}10mM$ to investigate the effect of the anionic surfactant. As a result, rejection rate of ferrous was the highest to 88.97% at 6mM. And we used ELS (Electrophoretic Light Scattering Spectrometer) to investigate particle size distribution of micellar aggregates depending on SDS concentration. Then distribution of large aggregates was the highest at 6mM. And we investigated effects of $N_2$-back-flushing time (BT) during periodic $N_2$-back-flushing on ceramic membranes. Finally optimal $N_2$-BT for NCMT-723l (pore size $0.10{\mu}m$) membrane was 20 sec.

• Korean Chemical Engineering Research
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• v.52 no.1
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• pp.58-62
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• 2014

Electrochemical ammonia synthesis from water and nitrogen using a Pt/GDC/Pt cell was experimentally investigated. Electrochemical analysis and ammonia synthesis in the moisture-saturated nitrogen environment were performed under the operating temperature range $400{\sim}600^{\circ}C$ and the applied potential range OCV (Open Circuit Voltage)-1.2V. Even though the ammonia synthesis rate was augmented with the increase in the operating temperature (i.e. increase in the applied current) under the constant potential, the faradaic efficiency was decreased because of the limitation of dissociative chemisorption of nitrogen on the Pt electrode. The maximum synthesis rate of ammonia was $3.67{\times}10^{-11}mols^{-1}cm^{-2}$ with 0.1% faradaic efficiency at $600^{\circ}C$.

• Clean Technology
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• v.17 no.2
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• pp.166-174
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• 2011

The xAl-yCe oxide catalysts with different mol ratios of Al/(Al+Ce) were prepared by a co-precipitation method and Pt supported on xAl-yCe oxide catalysts were synthesized by an incipient wetness impregnation method. The catalysts were characterized by X-ray Diffraction (XRD), $N_2$ sorption, and $H_2$/CO-temperature programmed reduction ($H_2$/CO-TPR) to correlate with catalytic activities in co oxidation. Among the catalysts studied here, Pt/1Al-9Ce oxide catalyst showed the highest activity in dry and wet reaction conditions and the catalytic activity showed a typical volcano-shape curve with respect to Al/(Al+Ce) mol ratio. When the presence of 5% water vapor in the feed, the temperature of $T_{50%}$ was shifted ca. $30^{\circ}C$ to lower temperature region than that in dry condition. From CO-TPR, the desorption peak of $CO_2$ on Pt/1Al-9Ce oxide catalyst showed the highest value and well correlated the catalytic performance. It indicates that the Pt/1Al-9Ce oxide catalyst has a large amount of active sites which can be adsorbed by co and easy to supplies the needed oxygen. In addition, the amount of pentacoordinated $Al^{3+}$ sites obtained through $^{27}Al$ NMR analysis is well correlated the catalytic performance.

• Korean Chemical Engineering Research
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• v.57 no.1
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• pp.133-141
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• 2019

High specific surface area zirconia with acid-basic property was synthesized by precipitation using reflux method or hydrothermal synthesis method using ammonium hydroxide solution as precipitant in the range of pH of Zr solution from 2 to 10. The prepared zirconia was characterized by the nitrogen adsorption, X-ray diffraction (XRD), isopropanol temperature programmed desorption (IPA-TPD), scanning electron microscopy and X-ray photoelectron spectroscopy, and the catalytic activity in the IPA decomposition reaction was correlated with the acid-basic properties. When using reflux method, high pH of Zr solution was required to obtain high fraction of tetragonal zirconia, and pure tetragonal zirconia was possible at pH 9 or higher. High pH was required to obtain high specific surface area zirconia, and the hydrous zirconia synthesized at pH 10 had high specific surface area zirconia of $260m^2g^{-1}$ even after calcination at $600^{\circ}C$. However, hydrothermal synthesis with high pressure under the same conditions resulted in very low specific surface area below $40m^2g^{-1}$ and monoclinic phase zirconia was synthesized. High pH of the solution was required to obtain high specific surface area tetragonal phase zirconia. In hydrothermal synthesis requiring high pressure, monoclinic zirconia was produced irrespective of the pH of the solution, and the specific surface area was relatively low. Zirconia with high specific surface area and tetragonal phase was predominantly acidic compared to basicity and only propylene, which was observed as selective dehydration reaction in IPA decomposition reaction, was produced.