• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.241-241
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• 2015

플라즈마 건식 식각 기술은 반도체 식각공정에서 효과적으로 이용되고 있으며, 반도체 소자의 크기가 줄어듬에 따라 미세하고 정확하게 식각 깊이를 제어 할 수 있는 원자층 식각기술 많은 관심을 받고 있다. 실리콘을 대체 할 수 있는 우수한 전기적 특성을 가진 III-V 화합물 반도체 재료인 InGaAs에 대한 원자층 식각을 통하여, 흡착가스에 대한 표면흡착 및 탈착가스에 대한 표면탈착 메커니즘을 고찰하였다. 또한, 성분 및 표면분석 장치를 이용하여 InGaAs 원자층 식각 특성에 대해 연구하였다.

• Korean Journal of Environmental Agriculture
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• v.5 no.2
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• pp.101-105
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• 1986

An adsorption and desorption experiment was conducted to utilize natural zeolite as cadmium adsorbent in wastewater. Adsorption of cadmium by natural zeolite was conformed to Freundlich's adsorption equation and natural zeolite was found to be effective adsorbent. The higher the cadmium concentration of solution, the more the adsorption amount of cadmium was and the adsorption was in the order of $Ca-<Nontreated-<H-{\leqq}Al-<Nazeolite$. Ion selectivity of natural zeolite in mixed solution increased in the order of Cd$NaCl<CaCl_2<AlCl_3<HCl$.

• Journal of Environmental Science International
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• v.5 no.2
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• pp.243-252
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• 1996

In order to investigate the effects of pH and organic matter content on cadmium adsorption and exchangeable cations desorption in soils, the adsorption isotherms of cadmium and the desorption isotherms of calcium and magnesium on four New jersey soils at four pH values were plotted, and the cadmium partition coefficients (Kd) were also calculated. The slopes of cadmium adsorption isotherms dramatically increased with increasing solution pH. Judging from Langmuir adsorption equations, the maximum adsorption quantities(b) of cadmium at high pH values were much greater than those at low pH values for the same soil. The partition coefficients increased greatly with increasing solution pH. The slopes of regression equations between partition coefficients and pH values were steep in the order of the organic matter content of the soils. The correlation coefficients (r2) between partition coefficient and organic matter content for soils. The correlation coefficients (r2) between partition coefficient and organic matter content for $1\times10^{-4}$M increased from 0.3027 at pH 4.0 to 0.9964 at pH 8.5 and from 0.2093 at pH4.0 at 0.9657 at pH 8.5 for$2\times10^{-4}$M ${Cd(NO_3)}_2$. The desorption quantities of calcium and magnesium decreased with increasing solution pH and increased with- increasing cadmium adsorption.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.1 no.1
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• pp.65-72
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• 2003

Adsorption and desorption characteristics of methyl iodide at high temperature conditions up to 25$0^{\circ}C$ by TEDA-impregnated activated carbon and silver-ion exchanged zeolite(AgX-10), which are used for radioiodine retention in nuclear facility, were experimentally evaluated. In the range of temperature from 3$0^{\circ}C$ to 25$0^{\circ}C$, the adsorption capacity of base activated carbon decreased sharply with increasing temperature but that of TEDA-impregnated activated carbon showed higher value even at high temperature ranges. Especially, the residual amount of methyl iodide after desorption on TEDA-AC represented 30% lower value than that on AgX-10. However, it can be used as an adsorbent for the removal of methyl iodide up to 15$0^{\circ}C$ if it is preventing explosion by Ignition. The breakthrough curves of methyl iodide in the fixed bed packed with AgX-10 uP to 40$0^{\circ}C$ were compared upon the effects of bed temperatures, bed depth and input concentration of methyl iodide. Removal mechanism of methyl iodide on AgX-10 was proposed, based on the analysis of by-product gas generated from adsorption reaction.

• Applied Chemistry for Engineering
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• v.18 no.6
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• pp.592-598
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• 2007

The adsorption capability of cobalt phthalocyanine derivatives was investigated by means of X-ray diffractometor (XRD), FT-IR spectroscopy, scanning electron microscopy (SEM), and temperature programmed desorption (TPD). According to TPD results for ammonia, cobalt phthalocyanine derivatives showed two desorption peaks at low temperature ($100{\sim}150^{\circ}C$) and high temperature ($350{\sim}400^{\circ}C$) indicating that there were two kinds of acidities. Tetracarboxylic cobalt phthalocyanine (Co-TCPC) has a stronger desorption peak (chemical adsorption) at high temperature and a weaker desorption peak (physical adsorption) at low temperature than cobalt phthalocyanine (Co-PC). The specific surface areas of Co-TCPC and Co-PC were 37.5 and $18.4m^2/g$, respectively. The pore volumes of Co-TCPC and Co-PC were 0.17 and $0.10cm^3/g$, respectively. The adsorption capability of triethyl amine calculated by breakthrough curve at 120 ppm of equilibrium concentration was 24.3 mmol/g for Co-TCPC and 0.8 mmol/g for Co-PC. The removal efficiencies of dimethyl sulfide of Co-TCPC and Co-PC in batch experiment of 225 ppm of initial concentration were 92 and 18%, respectively. The removal efficiencies of trimethyl amine of Co-TCPC and Co-PC in batch experiment of 118 ppm of initial concentration were 100 and 17%, respectively.

• Journal of the Korean GEO-environmental Society
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• v.15 no.12
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• pp.61-69
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• 2014

Carboxymethyl-${\beta}$-cyclodextrin (${\beta}$-CMCD), as a biodegradable surfactant with hydrophobic and hydrophilic properties, has potential advantages of being applicable to the simultaneous treatment of multiple contaminated soils. In this study, the desorption behaviors of r adionuclides such as cobalt (Co), strontium (Sr), and cesium (Cs) from the soil contaminated with them were experimentally investigated and the effectiveness of CMCD as a desorbent was evaluated. The desorption equilibrium of used radionuclides could be achieved within 1~3 hr and the desorption ratio from kaolin was higher than that from natural soil. The addition of CMCD of 2 g/L increased the desorption ratio by 5~20 % and the desorption ratio of used r adionuclides was shown in the order of Co > Cs > Sr. The experimental desorption data were fitted successfully by pseudo-second order kinetic model and the desorption rate of the r adionuclides was shown in the order of Cs > Co > Sr. Hysteresis between adsorption and desorption of the r adionuclides, as shown in the order of Sr > Co > Cs, increased as the desorption rate decreased. Consequently, it could be considered that the desorption rate was one of the significant factors of the hysteresis. The addition of CMCD as desorbent increased the amount of desorbed radionuclides and decreased the hysteresis. However, the CMCD could not completely desorb the radionuclides from soils even though the excess of CMCD was added.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2005.11a
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• pp.405-406
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• 2005

• Journal of the Korean Chemical Society
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• v.23 no.2
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• pp.88-93
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• 1979

The adsorption of propylene on copper(II)-exchanged zeolite Y was studied by temperature programmed desorption (TPD) technique and electron spin resonance. The amount of propylene adsorbed increased with increasing copper ion content. Four TPD peaks with desorption temperature maxima at $108^{\circ}C({\alpha})$, $243^{\circ}C({\beta})$, $284^{\circ}C({\gamma})$ and $420^{\circ}C({\delta})$ were observed (heating rate: $6.4^{\circ}C$/min). ${\alpha}$Peak which was also observed in the TPD of propylene from NaY may be assigned to propylene physically adsorbed on the zeolite surface, ${\beta}$ and ${\gamma}$ peaks to the chemisorbed propylene either on copper ion or Bronsted acid site produced by copper ion, and $\delta$ peak to cracking products from the polymeric material formed from propylene adsorbed.

• Clean Technology
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• v.26 no.2
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• pp.137-144
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• 2020

Metal-impregnated activated carbons were prepared via ultrasonic-assisted impregnation method for regeneration and low ammonia concentration. Magnesium and copper were selected as metals, while chloride (Cl^-) and nitrate (NO₃^-) precursors were used to impregnate the surface of activated carbon. The physical and chemical properties of the prepared adsorbents were characterized by TGA, BET, and NH₃-TPD. The ammonia breakthrough test was carried out using a fixed bed and flowing ammonia gas (1000 mg L^-1 NH₃, balanced N₂) at 100 mL min^-1, under conditions of temperature swing adsorption (TSA) and pressure swing adsorption (PSA, 0.3, 0.5, 0.7, 0.9 Mpa). The adsorption and desorption performance of ammonia were in the order of AC-Mg(Cl) > AC-Cu(Cl) > AC-Mg(N) > AC-Cu(N) > AC through NH₃-TPD and TSA and PSA processes. AC-Mg(Cl) using MgCl₂ showed the average adsorption amount of 2.138 mmol/g at TSA process. Also, AC-Mg(Cl) showed the highest initial adsorption amount of 3.848 mmol/g at PSA 0.9 Mpa. When metal impregnated the surface of the activated carbon, it was confirmed that not only physical adsorption, but also chemical adsorption increased, making enhancement in adsorption and desorption performances possible. Also, the prepared adsorbents showed stable adsorption and desorption performances despite repeated processes, confirming their applicability in the TSA and PSA processes.

• Economic and Environmental Geology
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• v.56 no.5
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• pp.603-618
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• 2023

This study focused on evaluating the suitability of the WRK (waste repository Korea) bentonite as a buffer material in the SNF (spent nuclear fuel) repository. The U (uranium) adsorption/desorption characteristics and the adsorption mechanisms of the WRK bentonite were presented through various analyses, adsorption/desorption experiments, and kinetic adsorption modeling at various pH conditions. Mineralogical and structural analyses supported that the major mineral of the WRK bentonite is the Ca-montmorillonite having the great possibility for the U adsorption. From results of the U adsorption/desorption experiments (intial U concentration: 1 mg/L) for the WRK bentonite, despite the low ratio of the WRK bentonite/U (2 g/L), high U adsorption efficiency (>74%) and low U desorption rate (<14%) were acquired at pH 5, 6, 10, and 11 in solution, supporting that the WRK bentonite can be used as the buffer material preventing the U migration in the SNF repository. Relatively low U adsorption efficiency (<45%) for the WRK bentonite was acquired at pH 3 and 7 because the U exists as various species in solution depending on pH and thus its U adsorption mechanisms are different due to the U speciation. Based on experimental results and previous studies, the main U adsorption mechanisms of the WRK bentonite were understood in viewpoint of the chemical adsorption. At the acid conditions (＜pH 3), the U is apt to adsorb as forms of UO₂²⁺, mainly due to the ionic bond with Si-O or Al-O(OH) present on the WRK bentonite rather than the ion exchange with Ca²⁺ among layers of the WRK bentonite, showing the relatively low U adsorption efficiency. At the alkaline conditions (>pH 7), the U could be adsorbed in the form of anionic U-hydroxy complexes (UO₂(OH)₃^-, UO₂(OH)₄^2-, (UO₂)₃(OH)₇^-, etc.), mainly by bonding with oxygen (O^-) from Si-O or Al-O(OH) on the WRK bentonite or by co-precipitation in the form of hydroxide, showing the high U adsorption. At pH 7, the relatively low U adsorption efficiency (42%) was acquired in this study and it was due to the existence of the U-carbonates in solution, having relatively high solubility than other U species. The U adsorption efficiency of the WRK bentonite can be increased by maintaining a neutral or highly alkaline condition because of the formation of U-hydroxyl complexes rather than the uranyl ion (UO₂²⁺) in solution,and by restraining the formation of U-carbonate complexes in solution.