• 한국결정학회지
• /
• 제14권2호
• /
• pp.67-72
• /
• 2003

Graphite powders were coated with ZrO₂ by the controlled hydrolysis of a DI water, ethanol and DI water+ethanol solutions. The hydrolysis process was carried out with temperature control because of the low wettability of Zr ions to the surface of the graphite. PVA was added to the solution for the enhancement of metal ion adsorption. The surface of the graphite powders coated with ZrO₂ was observed by SEM and TEM. There are two types of ZrO₂ particles with the condition of ZrOCl₂°§8H₂O aqueous solutions were used; (a) primary particles a few nm in size and (b) secondary particles with ∼0.1 ㎛ size were obtained. The graphite powders coated in 50% ethanol-50% DI water solution of Zr(SO₄)₂ㆍ4H₂O have the relatively uniform coating layer and the starting temperature of oxidation was 100℃ higher than the raw graphite.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2006년도 춘계학술대회 논문집
• /
• pp.475-476
• /
• 2006

Self-assembled monolayers (SAMs) formed by the adsorption of alkanethiols, HS(CH2)nX, where X is an organic functional group, onto gold surfaces have attracted widespread interest as templates for the fabrication of molecular and biomolecular microstructures. Previously photopatterning has been thought of as being restricted to the micron scale, because of the well-known diffraction limit. So, we have explored a novel approach to nanofabrication by utilizing a femtosecond laser.

• 한국수처리학회지
• /
• 제26권6호
• /
• pp.13-26
• /
• 2018

This research was conducted to elucidate the removal mechanism of heavy metals and sulfate ion from acid mine drainage(AMD) by porous zeolite-slag ceramics (ZS ceramics) packed in a column reactor system. The average removal efficiencies of heavy metals and sulfate ion from AMD by the 1:3(Z:S) porous ZS ceramics in the column reactor under the HRT condition of 24 hours were Al 97.5%, As 98.8%, Cd 86.1%, Cu 96.2%, Fe 99.7%, Mn 64.1%, Pb 97.2%, Zn 66.7%, and $SO_4{^{2-}}$ 76.0% during 121 days of operation time. The XRD analysis showed that the ferric iron from AMD could be removed by adsorption and/or ion-exchange on the porous ZS ceramics. In addition it was known that Al, As, Cu, Mn, and Zn could adsorb or coprecipitate on the surface of Fe precipitates such as schwertmannite, ferrihydrite, or goethite. The EDS analysis revealed that Al, Fe, and Mn, which were of relatively high concentration in the AMD, would be adsorbed and/or ion-exchanged on the porous ZS ceramics and also exhibited that Al, Cu, Fe, Mn, and Zn could be precipitated as the form of metal hydroxide or sulfate and adsorbed or coprecipitated on the surface of Fe precipitates. The microscopic results on the porous ZS ceramics and precipitated sludge in a column reactor system suggested that the heavy metals and sulfate ion from AMD would be eliminated by the multiple mechanisms of coprecipitation, adsorption, ion-exchange as well as precipitation.

• Geomechanics and Engineering
• /
• 제7권2호
• /
• pp.183-200
• /
• 2014

The expansivity of clayey soils is a complicated phenomenon which may affect the stability of geotechnical structures and geo-environmental projects. In all common factors for the monitoring of soil expansion, less attention is given to anion type of pore space solutions. Therefore, this paper is concerned with the impact of various concentrations of different inorganic salts including NaCl, $Na_2SO_4$, and $Na_2CO_3$ on the macro and microstructure behavior of the expandable smectite clay. Comparison of the responses of the smectite/NaCl and smectite/$Na_2SO_4$ mixtures indicates that the effect of anion valance on the soil engineering properties is not very pronounced, regardless of the electrolyte concentration. However, at presence of carbonate as potential determining ions (PDIs) the swelling power increases up to 1.5 times compared to sulfate or chloride ions. The samples with $Na_2CO_3$ are also more deformable and show lower osmotic compressibility than the other mixtures. This demonstrates that the barrier performance of smectite greatly decreases in case of anions with the non-specific adsorption (e.g., $Cl^-$ and $SO{_4}^{2-}$) as the salinity of solution increases. Based on the results of the X-ray diffraction and sedimentation tests, the high soil volumetric changes upon exposure to carbonate is attributed to an increase in the repulsive forces between smectite basic unit layers due to the PDI effect of $CO{_3}^{2-}$ and increasing the pH level which enhance the buffering capacity of smectite. The study concluded that the nature of anion through its influence on the re-arrangement of soil microstructure and osmotic phenomena governs the hydro-mechanical parameters of expansive clays. It seems not coinciding with the double layer theory of the Gouy-Chapman double layer model.

• 대한화학회지
• /
• 제31권4호
• /
• pp.328-333
• /
• 1987

$C_18$ 역상 충전제에 1-eicosylsulfate($C_{20}H_{41}SO_4^-$)를 흡착하는 조건을 조사하였으며 $1.46{\times}10^{-4}M$의 흡착용액(25% 아세토니트릴 수용액) 1.2l를 통과시켰을 때 흡착평형이 일어났다. 이 분리관은 0.05 M ${\alpha}$-HiBA 용리액 10l까지 안정하였으며 Eu, Nd, Ce , La에 대한 분리관효율은 0.15M ${\alpha}$-HiBA 용리액 1.0ml/min에서 약 0.04 mm의 HETP를 나타내었다. 이 흡착분리관으로 희토류 원소 및 전이원소들을 개별 분리하였다.

• 한국결정성장학회지
• /
• 제6권4호
• /
• pp.571-583
• /
• 1996

1 mM의 $[Fe(CN)_{6}]^{3-}/[Fe(CN)_{6}]^{4-}$ 이온이 첨가된 0.5 M $K_{2}SO_{4}$용액에서 Impedance spectroscopy를 통하여 비교적 porous한 표면조직을 갖는 흑연재료인 electrographite와 graphite foil의 계면의 전기화학적 거동을 조사하였다. 이들 두 흑연재료의 변전위 전류 전압곡선의 경우 전극표면의 구조로 인하여 비교적 높은 전류가 나타났으며, graphite foil의 경우 높은 이중층 용량이 나타났다. 또한 두 재료 모두 field transport의 작용에 의해 분극증가에 따른 임피던스 스펙트럼의 변화와 Faraday-임피던스의 변화가 크게 나타나지 않았다. 특히 electrographite의 경우 전극계면에서 흡착현상이 나타났으며, 양극분극의 증가에 의해 흡착현상은 현저하게 증가하였다.

• 대한화학회지
• /
• 제20권2호
• /
• pp.153-157
• /
• 1976

1기압하에서 한국산 소나무로부터 lignin을 추출할 수 있는 실험실에서의 최적 조건을 구했고, m.p, 증색반응, IR등의 방법으로 순수한 lignin임을 확인했다. 추출한 순수 lignin을 진한 황산으로 탄화한 후 전기로 속에서 650$^{\circ)C$로 공기 부활하여 활성탄을 제조하였다. 이 활성탄의 광전 비색계에 의한 흡착능을 조사한 결과 89%였다.

• Advances in materials Research
• /
• 제13권2호
• /
• pp.103-114
• /
• 2024

Zeolites are microporous materials that find applications in different fields due to their numerous interesting properties. This research investigated the effect of leaching on unheated Ifon kaolin in dilute hydrochloric acid and sulphuric acid. The hydrothermal method synthesized zeolite-X type, and the resulting sample was characterized using different techniques. The silica/alumina ratio in the synthesized sample was approximately 5.6, while Infrared spectra confirmed that the synthesized material was Zeolite-X. Based on the X-ray diffraction patterns, other phases were also formed in addition to zeolite-X crystals. Thermogravimetry results indicated that the synthesized zeolite was relatively stable below 500℃, so its weight loss was only 13% after heating to about 200℃. A differential thermal analyzer confirmed this amount of weight loss, and endothermic and exothermic reactions were also observed for the samples calcined respectively at 700 and 900℃. Based on Brunauer-Emmett-Teller (BET) analyses, samples at 700℃ showed slower adsorption-desorption isotherms, pore volume, and sizes than those at 900℃. These results have shown that leaching and calcination temperature significantly affect the type of zeolite produced.

• 한국대기환경학회지
• /
• 제23권1호
• /
• pp.84-96
• /
• 2007

We performed the experiments to manufacture the hydrophobic $200cells/in^2$-zeolite honeycomb using HY-type zeolite of Si/Al ratio of 80 for separating and removing the VOCs emitted from small and medium size-plants by adsorption and to determine the drying method for the honeycomb at $105^{\circ}C$ without cracking, then measured performances of the honeycomb to adsorb the benzene, o-xylene, and MEK and to desorb the benzene and MEK saturated on the honeycomb by the nitrogen gas as the desorption gas. As a results, the good honeycomb was formed and the honeycomb was not cracked when the mixing ratio of the zeolite to bentonite to methyl cellulose to polyvinyl alcohol to glycerine to water is 100 : 8.73 : 2.18 : 4.19 : 1.38 : 126 and dried the honeycomb at $105^{\circ}C$ for 24 hours in the drying oven. The shape of the dried honeycomb was not changed after calcination, and the compressive strengths of the honeycomb after drying and calcination were 6.7 and $0.69kg/cm^2$, respectively. The adsorption efficiencies of the honeycomb for benzene, o-xylene, and MEK were $92{\sim}96%$ at the room temperature. The desorption efficiency at $180^{\circ}C$ was higher than that at $150^{\circ}C\;by\;1.5{\sim}13.8%$ depending on the flow rate of the nitrogen gas, and it was found that desorption efficiency is higher than 85% at $180^{\circ}C$ and 1.0L/min of the nitrogen gas. At $180^{\circ}C$ and 0.2 L/min, the concentration of the benzene and MEK in the used desorption gas are higher than 40,000 and 50,000ppm, respectively, so it be used as the fuel for preheating the desorption gas fed into the column in desorption cycle.

• 한국응용과학기술학회지
• /
• 제29권4호
• /
• pp.594-598
• /
• 2012

고분자 전해질막 연료전지는 연료극의 연료와 공기극의 공기에 각각 $H_2S$와 $SO_2$이 포함되어 있을 때 그 성능이 심각하게 감소한다. 본 연구는 고분자전해질막 연료전지의 공기극과 연료극에 1 ppm에서 10 ppm의 불순물 가스를 공급하여 전기적 성능측정을 통해 복합적인 황불순물이 단위전지에 미치는 영향을 확인하였다. 최적의 운전조건에서 불순물가스를 피독하였을 때 $SO_2$와 $H_2S$의 농도가 증가할수록 성능이 급격히 감소하였다(단위전지 온도 $65^{\circ}C$, 상대습도 100%). 그리고 황의 흡착은 MEA의 백금 촉매층 표면서 일어나며, 불순물 가스가 MEA에 누적되는 것을 확인하였다. 1, 3, 5, 및 10 ppm 4회의 연속적인 피독 후 연료전지의 성능이 0.71 V에서 0.54 V(76 %)로 감소하였다.