• 공업화학
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• 제17권6호
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• pp.653-657
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• 2006

본 연구는 이온교환 수지와 섬유를 복합한 이온교환체를 이용하여 $NO_{2}$의 흡착특성을 고찰하였다. 수지량의 변화에 따른 $NO_{2}$의 흡착은 흡착시간이 경과함에 따라 증가하였다. 초기농도 변화에 따른 $NO_{2}$ 흡착은 초기 농도가 증가함에 따라 흡착량이 증가하였으며 900 ppm의 경우 20 min 내외에 약 40% 흡착되었다. 한편 유속변화에 따른 $NO_{2}$의 흡착은 유속이 증가함에 20~40 L/min까지 흡착량은 감소하였고, 유속이 10 L/min에서 최대 45% 흡착되었으며, 함수율 변화에 따른 $NO_{2}$ 흡착량은 10 min 전후에서 약 15%로 매우 낮게 나타났다.

• 한국물환경학회지
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• 제22권6호
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• pp.991-995
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• 2006

The layered double hydroxide with the insertion of chloride ions (LDH-Cl), which was synthesized by the co-precipitation method, was applied to investigate the fundamental aspects of the absorptive agent for phosphate removal from wastewater. The adsorption capacity was best described by the Langmuir-FreundIich isotherm, and the estimated isotherm parameters indicate that the LDH-CI capacity for the phosphate removal is much higher than that observed using a natural adsorbent material such iron oxide tailing. The kinetic experiment also showed that the LDH-Cl adsorption reaction rapidly at the adsorptive rate of 0.55 mg-P/g-LDH/min, implying that this adsorbent can be of use in the full-scale applications. The pH had a minimal effect on the LDH adsorption capacity in the range of 5 to 11, although the capacity dropped at the low pHs because of the change in LDH surface properties. Furthermore, other anions such as $Cl^-$ and $NO_3{^-}$ commonly found in the wastewater streams insignificantly affected the phosphate removal efficiencies, while $HCO_3{^-}$ ions had a negative effect on the LDH adsorption capacity due to its high selectivity. The phosphate removal experiment using the actual secondary effluent from a wastewater treatment plant showed the similar decrease in adsorption capacity, indicating that the bicarbonate ions in the wastewater were competing with phosphate for the adsorptive site in the surface of the LDH-Cl. Overall, the synthetic adsorbent material, LDH-Cl, can be a feasible alternative over other conventional chemical agents, since the LDH-Cl exhibits the high phosphate removal capacity with the low sensitivity to other environmental conditions.

• 한국지구과학회지
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• 제23권1호
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• pp.97-104
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• 2002

Mulgeum, Yangseong, Maeri and Kimhae iron ore deposits in Gyeongnam Province are hydrothermal skarn type magnetite ore deposits in propylitized andesitic rock near the contact with Cretaceous Masanite. Symmetrical zoned skarns are commonly developed around the magnetite veins. The skarn zones away from the vein are quartz-garnet skarn, epidote skarn and epidote-orthoclase skarn. Oxygen isotope analyses of coexisting minerals from andesitic rock, Masanite and major skarn zones, and of magnetite, hematite and quartz were conducted to provide the information on the formation temperature, the origin and the evolution of the hydrothermal solution forming the iron ore deposits. Becoming more distant from the ore vein, temperatures of skarn zones represent the decreasing tendency, but most ${\delta}^{18}O$ and ${\delta}^{18}O_{H2O}$ values of skarn minerals represent no variation trend, and also the values are relatively low. Judging from all the isotopic data from the ore deposits, the major source of hydrothermal solution altering the skarn zones and precipitating the ore bodies was magmatic water derived from the deep seated Masanite. This high temperature hydrothermal solution rising through the fissures of propylitized andesitic rock was mixed with some meteoric water, and occurred the extensive isotopic exchange with the propylitized andesitic rock, and formed the skarns. During these processes, the temperature and ${\delta}^{18}O_{H2O}$ value of hydrothermal solution were lowered gradually. At the main stage of iron ore precipitation, because all the alteration was already finished, the new rising hydrothermal solution formed only the magnetite ore without oxygen isotopic exchange with the wall rock.

• 공업화학
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• 제10권2호
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• pp.218-224
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• 1999

원자로 정지시 혼상 탈염기의 최적 운전방법을 제안할 목적으로 산성-산화성 분위기에서 저농도의 Ni, Co 및 Ag 이온이 함유된 모의 냉각재 용액의 연속식 이온교환특성을 연구하였다. 금속 이온의 제거 용량에 미치는 양이온 교환수지 형태의 효과로서 $H^+$형 수지의 성능은 $Li^+$형 수지의 성능보다 약 6% 정도 높은 것으로 나타났다. 혼합층 이온교환 방법인 양이온과 음이온 수지의 혼합은 비혼합시와 비교하여 금속 이온들의 제거 용량에는 영향을 미치지 않았으나 금속 이온들의 파과곡선의 기울기를 매우 조금 증가시켰다. 냉각재의 산성-산화성 분위기와 관계된 영향으로서 붕산의 첨가는 금속 이온들의 파과곡선의 기울기를 매우 작게 감소시킨 반면, 과산화수소의 첨가는 금속이온들의 제거 용량을 약간 감소시켰다.

• Journal of Electrochemical Science and Technology
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• 제10권3호
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• pp.302-312
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• 2019

The voltage produced from the salinity gradient in reverse electrodialysis (RED) increases proportionally with the number of cell pairs of alternating cation and anion exchange membranes. Large-scale RED systems consisting of hundreds of cell pairs exhibit high voltage of more than 10 V, which is sufficient to utilize water electrolysis as the electrode reaction even though there is no specific strategy for minimizing the overpotential of water electrolysis. Moreover, hydrogen gas can be simultaneously obtained as surplus energy from the electrochemical reduction of water at the cathode if the RED system is equipped with proper venting and collecting facilities. Therefore, RED-driven water electrolysis system can be a promising solution not only for sustainable electric power but also for eco-friendly hydrogen production with high purity without $CO_2$ emission. The RED system in this study includes a high membrane voltage from more than 50 cells, neutral-pH water as the electrolyte, and an artificial NaCl solution as the feed water, which are more universal, economical, and eco-friendly conditions than previous studies on RED with hydrogen production. We measure the amount of hydrogen produced at maximum power of the RED system using a batch-type electrode chamber with a gas bag and evaluate the interrelation between the electric power and hydrogen energy with varied cell pairs. A hydrogen production rate of $1.1{\times}10^{-4}mol\;cm^{-2}h^{-1}$ is obtained, which is larger than previously reported values for RED system with simultaneous hydrogen production.

• 마이크로전자및패키징학회지
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• 제13권1호통권38호
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• pp.57-61
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• 2006

연료전지는 연료(수소)의 화학적 반응에 의해 축적된 화학에너지를 전기에너지로 변환하여 직류 전기를 발생시키는 에너지원이다. 연료전지는 질소나 유황산화물 등의 유해한 물질을 방출하지 않으며 기계적 동력부가 없고 거의 무소음으로 운전되는 이점을 가진다. 수소연료에 의한 연료전지는 그들의 부산물로써 열과 물을 방출한다. 연료전지를 이용한 응용분야의 확대로 인해 화석연료나 수입 석유의 의존도를 현저히 감소시킬 수 있다. 본 논문에서는 이러한 연료전지 (PEMFC, Proton Exchange Membrane Fuel Cell)의 출력을 치대한 활용하고 발전시스템의 안전운전을 위한 전력변환기(PCS, Power Conditioning System)에 대해 연구하였다. 본 논문에서는 고효율로 운전하는 새로운 전력변환 회로토폴로지를 설계하고, 발전시스템에 적용하여 각종 실험을 통하여 그 타당성을 입증하였다. 그 결과 연료전지 발전시스템은 고성능으로 동작되는 전력변환기에 의해 발전시스템의 효율과 성능을 향상시키게 된다.

• Journal of Welding and Joining
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• 제28권1호
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• pp.66-71
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• 2010

With large specific strength and outstanding corrosion resistance and erosion resistance in sea water, titanium and titanium alloy are widely used in heat exchanger production. In particular, pure titanium demonstrates outstanding molding performance and may be considered optimal for production of heat exchanger. Since titanium is very vulnerable to oxidation and embrittlement during welding, processes with less heat input are widely used, and laser welding is widely applied by considering production performance and shield etc in atmosphere. So far, 1st report and 2nd report compared and analyzed embrittlement degrees by bead colors of weldment through oxygen and nitrogen quantitative analysis and hardness measurement, and evaluated welding performance and mechanical properties of butt welding. This study evaluated field applicability of lap welding to heat exchange plate of LPG re-liquefaction device for ships through tensile stress test, hardness test and internal pressure test etc after deducing optimal weding condition and applying to actual heat exchange plate. In bead overlap area, the experiment produced sound welds with no porosity or defect by increasing and decreasing laser power, and tensile-shear test results indicated virtually the same tension and yield strength as base metal. As a result of measuring hardness at lateral cross section and bead overlap zone of actual heat exchanger welds, hardness difference within 20Hv was produced at base metal, HAZ and weldment, and as a result of pneumatic and hydraulic pressure test, no leakage occurred.

• 자원리싸이클링
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• 제29권5호
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• pp.38-47
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• 2020

본 연구에서는 SCR 탈질 폐촉매의 소다배소-수침출 공정을 통해 얻은 침출액으로부터 강염기성 음이온교환수지인 Lewatit monoplus MP 600을 사용하여, V과 W의 분리/회수를 위한 흡착반응에 영향을 미치는 인자들에 대하여 알아보고, 이를 통하여 흡착 메커니즘을 조사하였다. V과 W 혼합용액의 경우 pH 2-6에서는 두 이온 모두 높은 흡착률을 보였지만, pH 8에서 W의 흡착은 크게 저하되었다. 흡착등온실험에서 V과 W 모두 Langmuir 흡착등온식에 적합하였고, 반응속도론적 고찰 결과 pseudo-second-order에 적합하였다. 침출액에서 V과 W의 흡착을 저해하는 Si를 제거하기 위하여 H₂SO₄로 pH를 조절하여 흡착실험을 수행한 결과, pH 8.5에서 가장 낮은 W 흡착률을 보였다. W의 탈착은 강산성 용액에서 거의 이루어지지 않았으며 V은 강산성 용액과 강염기성 용액 모두에서 탈착이 잘 이루어졌다.

• Bulletin of the Korean Chemical Society
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• 제9권6호
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• pp.368-376
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• 1988

Transition metal PSSA ionomers containing Co(II), Ni(II), Cr(III), Ru(III), and Rh(III) are investigated by IR, Far-IR, UV-Vis and DSC. Reliable IR Spectroscopic criteria are established for assessing the degree of ion-exchange of PSSA ionomers and the local structures around metal cations in them. In the hydrated transition metal PSSA ionomers, the ionic groups are solvated by water molecules and there is no significant interactions between sulfonate group and metal cations. The visible spectra indicated that metal cations are present as [M$(H_2O)_6$]$^{n+}$ with Oh symmetry. Their $T_g$ values increase as the extent of ionic site concentration increases, but there is no direct dependence of $T_g$ on the nature of metal cations or their oxidation states. Thus, the water content in PSSA ionomer is found to have dominant influence on $T_g$ of hydrated transition metal PSSA ionomers. Dehydration of the hydrated transition metal PSSA ionomers results in direct interaction between ionic groups and significant color changes of the ionomers due to the changes of the local structures around metal cations. On the base of spectral data, their local structures are discussed. In case of dehydrated 12.8 and 15.8 mol % transition metal PSSA ionomers, no glass transition is observed in 25-$250^{\circ}C$ region and this is believed to arise from the formation of highly crosslinked structures caused by direct coordination of sulfonate groups of metal cations. In the 6.9 mol % transition metal PSSA ionomers, the glass transition is always observed whether they are hydrated or dehydrated and this is though to be caused by the sufficient segmental mobility of the polymer backbone.

• 한국환경과학회지
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• 제9권3호
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• pp.253-259
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• 2000

The purpose of this study is to investigate the physicochemical characteristics of salinization of groundwater at the estern area of Cheju island. For this purpose, the major ions of groundwater, spring water are analyzed. The concentration of $Cl^-$ and Na^++K^+$/ contained in the groundwater at near the coastline are higher than those at inland area away from the coastline. The water quality components of groundwater observed at this area can be classified into 4 types such as Na-Cl, $HCO_3, Na-Cl-HCO_3$ and Ca-HCO$_3$. The concentration ratio of $SO_4^1 to Cl^- is 0.1354(R^2=0.972)$ at this area. This value is very similar with Dittomer's ratio of 0.13. For Na^+, K^+, and Mg^{2+}/ versus Cl^-$, their ratios also show a significant relationship between sea water and groundwater in this area. From the chloride-bicarbonate ratio, it can be estimated that the intrusion distance of seawater from coastline to inland area is 2.8km at Onpyung-Nansan, Sangdo and Pyungdae areas, and 5.4km at Kosung-Susan area. The mixing ratio between seawater and fresh water by the intrusion of seawater is decreased with the distance toward inland from coastline. This ratio(fresh water : seawater) is 80:20 in spring water adjacent the coastlines, Onpyung area and 99.8:0.2 in the well at No.3 of Susan located at inland away from the coastline. The concentration of $Na^+$ observed at field is 25~45% lower than that theoretically calculated by this mixing ratio. Based on the data of EC, the equipotential line of 500$\mu$mhos/cm is located at 4~5km poing at Kosung-Susan area and 2.5km point at the other area. The equation of correlation between $Cl^-$ concentration and EC values is $Cl^-$=0.1927EC-16.683 for the area lower than 500 $\mu$mhos/cm and $Cl^-$=0.2773EC for the area beyond 500 $\mu$mhos/cm.