• Title/Summary/Keyword: Selective adsorption

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Li+- and H+-Exchanged Low-Silica X Zeolite as Selective Nitrogen Adsorbent for Air Separation

  • Kim, Jin-Bae
    • Bulletin of the Korean Chemical Society
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    • v.24 no.12
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    • pp.1814-1818
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    • 2003
  • $Li^+$ and $H^+$ co-exchanged LSXs (Li-H-LSX) with various ratios of $Li^+$ and $H^+$ were prepared, and those adsorption characteristics of nitrogen and oxygen were compared with Li-Na-LSX and Li-Ca-LSX. Li-H-LSX showed higher nitrogen capacity and selectivity than that of Li-Na-LSX in the wide range of Li-exchanged ratio. The nitrogen capacity of Li-Ca-LSX was slightly higher than that of fully Li- or Ca-exchanged LSX (Li- LSX or Ca-LSX). However, Li-Ca-LSX showed low nitrogen/oxygen adsorption selectivity until the Li content reached about 80%, which was a tendency near that of Ca-LSX.

A Study on Selective Adsorption of Phenanthrene Dissolved in Triton X-100 Solution using Activated Carbons (활성탄을 이용한 Triton X-100 용액에서의 phenanthrene의 선택적 흡착에 관한 연구)

  • Ahn, Chi-Kyu;Kim, Young-Mi;Woo, Seung-Han;Park, Jong-Moon
    • Journal of Soil and Groundwater Environment
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    • v.11 no.2
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    • pp.13-21
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    • 2006
  • Polycyclic aromatic hydrocarbons (PAHs) are widespread soil contaminants and major environmental concerns. PAHs have extremely low water solubility and are strongly sorbed to soil. A potential technology for remediation of PAHcontaminated soils is a soil washing with surfactant solutions. While the use of surfactants significantly enhances the performance of soil remediation, operation costs are increased. Selective adsorption of PAHs by activated carbons is proposed to reuse the surfactants in the soil-washing process. The adsorption isotherms of pure chemicals (Triton X-100 and phenanthrene) onto three granular activated carbons were obtained. The selective adsorption of phenanthrene in mixed solution was examined at various concentrations of phenanthrene and Triton X-100. The selectivity results were discussed with pore size distribution of activated carbons and molecular sizes of phenanthrene and the Triton X-100 monomer. The selectivity for phenanthrene was much larger than 1 regardless of the particle size of activated carbons. The selective adsorption using activated carbons with proper pore size distribution would greatly reduce the material cost for the soil washing process by the reuse of the surfactants.

Soil Properties Affecting the Adsorption of Lead (Pb의 흡착에 영향을 미치는 토양의 특성)

  • 박상원
    • Journal of Environmental Science International
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    • v.8 no.1
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    • pp.69-74
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    • 1999
  • Soil properties which affect the retention of Pb(I) were investigated in the laboratory. It was determined, through selective removal, that organic matter and Fe-oxides are of lesser importance in influencing Pb retention than are soil clay minerals. The following trend : clays > organic matter > Fe-oxides represents the relative importance of each constituent in the adsorption of Pb by soils. The consistently greater Pb uptake by surface over subsurface samples was apparently due to differences in organic matter content, inasmuch as organic matter removal from both resulted in similar adsorption characteristics. All five soils stooled exhibited a pH-dependent trend of adsorption. The extent of Pb adsorption was least at low pH values(4~5), was maximum in the neutral pH range, and leveled off or diminished under more alkaline conditions. There was no strong correlation between Pb uptake and soil cation exchange capacity as routinely measured by the NH$_4$OAc method. A knowledge of clay mineralogy in conjunction with soil pH is suggested as being the most reliable guide to predicting Pb retention by soils.

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STM Tip Catalyzed Adsorption of Thiol Molecules and Functional Group-Selective Adsorption of a Bi-Functional Molecule Using This Catalysis

  • Min, Yeong-Hwan;Jeong, Sun-Jeong;Yun, Yeong-Sang;Park, Eun-Hui;Kim, Do-Hwan;Kim, Se-Hun
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.08a
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    • pp.197-197
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    • 2011
  • In this study, in contrast with cases in which Scanning Tunneling Microscopy (STM) tip-induced reactions were instigated by the tunneling electrons, the local electric field, or the mechanical force between a tip and a surface, we found that the tungsten oxide (WO3) covered tungsten (W) tip of a STM acted as a chemical catalyst for the S-H dissociative adsorption of phenylthiol and 1-octanethiol onto a Ge(100) surface. By varying the distance between the tip and the surface, the degree of the tip-catalyzed adsorption could be controlled. We have found that the thiol head-group is the critical functional group for this catalysis and the catalytic material is the WO3 layer of the tip. After removing the WO3 layer by field emission treatment, the catalytic activity of the tip has been lost. 3-mercapto isobutyric acid is a chiral bi-functional molecule which has two functional groups, carboxylic acid group and thiol group, at each end. 3-Mercapto Isobutyric Acid adsorbs at Ge(100) surface only through carboxylic acid group at room temperature and this adsorption was enhanced by the tunneling electrons between a STM tip and the surface. Using this enhancement, it is possible to make thiol group-terminated surface where we desire. On the other hand, surprisingly, the WO3 covered W tip of STM was found to act as a chemical catalyst to catalyze the adsorption of 3-mercapto isobutyric acid through thiol group at Ge(100) surface. Using this catalysis, it is possible to make carboxylic acid group-terminated surface where we want. This functional group-selective adsorption of bi-functional molecule using the catalysis may be used in positive lithographic methods to produce semiconductor substrate which is terminated by desired functional groups.

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Ozone Condensation and Stable Supply by an Adsorption Method

  • Yang, Seong-Ho;Park, Yong-Pil;Lee, Joon-Ung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.04b
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    • pp.121-125
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    • 2000
  • An ozone condenser by a selective adsorption on the silica gel surface is constructed. Ozone density is evaluated by three methods; ultraviolet absorption, thermal decomposition and Q-mass analyzing methods. Thermal decomposition method is found to be available to the density evaluation from dilute to highly condensed ozone. The highest ozone density condensed by the adsorption method is evaluated to be 97 mol%.

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Enhancement of Selective Removal of Nitrate Ions from a Mixture of Anions Using a Carbon Electrode Coated with Ion-exchange Resin Powder (이온교환수지 분말이 코팅된 탄소전극을 이용한 음이온 혼합용액에서 Nitrate 이온의 선택적 제거율 향상)

  • Yeo, Jin-Hee;Choi, Jae-Hwan
    • Applied Chemistry for Engineering
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    • v.24 no.1
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    • pp.49-54
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    • 2013
  • We fabricated a composite carbon electrode to remove nitrate ions selectively from a mixed solution of anions. The electrode was fabricated by coating the surface of a carbon electrode with the nitrate-selective anion exchange resin (BHP55, Bonlite Co.) powder. We performed capacitive deionization (CDI) experiments on a mixed solution containing chloride, nitrate, and sulfate ions using a BHP55 cell constructed with the fabricated electrode. The removal of nitrate ions in the BHP55 cell was compared to that of a membrane capacitive deionization (MCDI) cell constructed with ion exchange membranes. The total quantity of ions adsorbed in BHP55 cell was $38.3meq/m^2$, which is 31% greater than that of MCDI cell. In addition, the number of nitrate adsorption in the BHP55 cell was $15.9meq/m^2$ (42% of total adsorption), 2.1 times greater than the adsorption in the MCDI cell. The results showed that the fabricated composite carbon electrode is very effective in the selective removal of nitrate ions from a mixed solution of anions.

Adsorption and separation behaviors of Y(III) and Sr(II) in acid solution by a porous silica based adsorbent

  • Wu, Hao;Kawamura, Taiga;Kim, Seong-Yun
    • Nuclear Engineering and Technology
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    • v.53 no.10
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    • pp.3352-3358
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    • 2021
  • Aiming at selective adsorption and separation of Y(III) from the Y(III)-Sr(II) group in acid solution, a silica-based TODGA impregnated adsorbent [(TODGA+1-dodecanol)/SiO2-P-F600] has been prepared. Batch adsorption experiments were conducted under the effect of contact time, acid concentration, solution temperature, and adsorption capacity etc. Chromatography recovery of more than 90% Y(III) was successfully achieved under elution with 0.01 M DTPA solution in nitric acid adsorption system, and 0.1 M HCl solution in hydrochloride adsorption system, respectively.

Development of Selective Adsorption Process with Various Pore Size A-type Zeolite on Removal of Acetylenes for Isoprene Purification (제올라이트 A를 이용하여 이소프렌에서 아세틸렌 제거를 위한 선택적 흡착공정 개발)

  • Jun, Kyung-Jin;Ahn, Byoung-Sung;Yoo, Kye-Sang
    • Applied Chemistry for Engineering
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    • v.21 no.5
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    • pp.548-552
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    • 2010
  • This study focused on the development of effective adsorbent to remove acetylenes for the purification of isoprene. The adsorbents with various pore sizes from $4{\AA}$ to $5{\AA}$ were prepared to investigate the effect of pore size on selective adsorption of acetylene as an impurity. The pore size of zeolite A was adjusted by ion-exchange between Na and Ca ions. The pore size of adsorbents has affected the removal of acetylenes selectively because of the kinetic diameter of acetylenes, such as 2-methyl-1-butyne-3-yen (IPA) and 2-butyne. In a batch adsorption experiment, 5A zeolite with pore size of $5{\AA}$ showed the highest removal capacity of 2-butyne. However, IPA was hardly removed from isoprene by the A-type zeolites. For the adsorption isotherm, modified Langmuir model was well fitted with 2-butyne adsorption. Moreover, the regeneration of adsorbent was carried out to determine optimum method. The adsorbent heated for 12 h at $300^{\circ}C$ was regenerated significantly.

A Study of $NH_3$ Adsorption/Desorption Characteristics in the Monolithic $NH_3-SCR$ Reactor (모노리스 $NH_3-SCR$ 반응기 내에서의 $NH_3$ 흡.탈착 특성에 대한 연구)

  • Wang, Tae-Joong;Baek, Seung-Wook;Jung, Myung-Geun;Yeo, Gwon-Koo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.3
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    • pp.125-132
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    • 2006
  • Transient kinetics of $NH_3$ adsorption/desorption and of SCR(selective catalytic reduction) of NO with $NH_3$ were studied over vanadium based catalysts, such as $V_2O_5/TiO_2$ and $V_2O_5-WO_3/TiO_2$. In the present catalytic reaction process, NO adsorption is neglected while $NH_3$ is strongly chemisorbed on the catalytic surface. Accordingly, it is ruled out the possibility of a reaction between strongly adsorbed $NH_3$ and NO species in line with the hypothesis of an Eley-Rideal mechanism. The present kinetic model assumes; (1) non-activated $NH_3$ adsorption, (2) Temkin-type $NH_3$ coverage dependence of the desorption energy, (3) non-linear dependence of the SCR reaction rate on the $NH_3$ surface coverage. Thus, the surface heterogeneity for adsorption/desorption of $NH_3$ is taken into account in this model. The present study extends the pure chemical kinetic model based on a powdered-phase catalytic system to the chemico-physical one applicable to a realistic monolith reactor.

Selective Adsorption Properties of Nitrate ion in Sulfate and Nitrate Solution by Bead and Fibrous Hybrid Ion Exchange Bed (비드와 섬유 혼성이온교환 베드를 이용한 황산이온과 질산이온 혼합용액에서 질산이온의 선택 흡착 특성)

  • 황택성;박명규
    • Polymer(Korea)
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    • v.27 no.1
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    • pp.69-74
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    • 2003
  • In this study, we have investigated the adsorption properties for nitrate ion in ground water using mixed resin type hybrid ion exchange (HIXF) and fiber type ion exchanger. Their swelling ratio (4.45 g/g) and ion exchange capacities (2.45 meq/g) were higer than the swelling ratio of IEC and IXF. Adsorption yield increased for nitrate $NO_3^-$ and sulfate $SO_4^{2-}$ ions were optimal at the concentration ratios of nitrate and sulfate below 1.0 and the adsorption yields were 100% and 20%, respectively. On the other hand it was shown that the degree of adsorpted for nitrate to pH 3, but it was little changed in the other pH range. We found that the selective adsorption capacity for nitrate was the optimal the mixing ratios of resin and fibrous ion exchanger of below 0.5.