• Title/Summary/Keyword: Surface adsorption

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Understanding of Protein Adsorption to Contact Lens Hydrogels with Varying Surface Energy (콘택트렌즈용 하이드로젤 계면에너지에 따른 단백질 흡착현상의 이해)

  • Jeon, So-Ha;Noh, Hye-Ran
    • Polymer(Korea)
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    • v.36 no.3
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    • pp.338-343
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    • 2012
  • Interfacial properties of commercially available soft contact lens hydrogels were studied to understand thermodynamic phenomena of protein adsorption. Hydrogel particles ($1{\times}1mm^2$) with varying water wettability were exposed to bovine serum albumin solutions for an hour. The remained albumin solutions were analyzed with Bradford assay method. The amount of protein adsorbed to hydrogels increased with protein solution concentrations following Langmuir isotherm. The partition coefficient ($P$) and Gibbs free energy cost of dehydrating the surface region by protein displacement upon adsorption increased with increasing hydrophilicity of contact lens. Understanding of physical chemistry in protein adsorption to contact lens materials enabled elucidating relationships between surface energy and albumin adsorption capacity.

Adsorption properties of surface - modified activated carbon (활성탄의 표면 구조 변화에 따른 흡착 특성 연구)

  • 김정렬;서문원;신창호;김영호;이근회;지상운
    • Journal of the Korean Society of Tobacco Science
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    • v.16 no.2
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    • pp.191-197
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    • 1994
  • Relationships between surface structure and adsorption properties of smoke components were investigated in surface-modified and un-modified activated carbon filter cigarettes. Commercially available activated carbon was treated with nitric acid and hydrogen peroxide as oxidant, and their pore volume, surface structure, BET surface area, pore type and size were studied. BET surface area and pore volume were decreased by nitric acid treatment, but median pore diameter was 8.1 $\AA$, which showed better development of pore compared with that of un-modified activated carbon, 6.9 $\AA$. In case of hydrogen peroxide treatment, BET surface area and pore volume were increased. Their pore was found to be a slit type based on V-t plot analysis. Neutralization capacities for bases of different strength (NaHCO3, Na2CO3, NaOEt and NaOH) showed that the majority of the acidic surface groups are of weak acidity. Modification of the activated carbon surface led to a slight change in adsorption properties when analyzing the smoke of triple-filter cigarette with surface-modified activated carbon.

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An influence on EDC/PPCPs adsorption onto single-walled carbon nanotubes with cationic surfactant (단일벽 탄소나노튜브의 미량유해물질 흡착거동에서 양이온 계면활성제의 영향에 관한 연구)

  • Heo, Jiyong;Lee, Heebum;Han, Jonghun;Son, Mihyang;Her, Namguk
    • Journal of Korean Society of Water and Wastewater
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    • v.28 no.4
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    • pp.419-429
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    • 2014
  • Recent studies have been reported the presence of Endocrine Disrupting Compounds, Pharmaceuticals and Personal Care Products (EDC/PPCPs) in surface and wastewater, which could potentially affect to the complicate behavior in coupled presence of nano-colloid particles and surfactants (adsorption, dispersion, and partitioning). In this study, the adsorption of EDC/PPCPs by Single Walled Carbon Nanotubes (SWNTs) as a representative of nano-particles in cationic surfactant solutions were investigated. Hydrophobic interactions (${\pi}-{\pi}$ Electron Donor-Acceptor) have been reported as a potential adsorption mechanisms for EDC/PPCPs onto SWNTs. Generally, the adsorptive capacity of the relatively hydrophobic EDC/PPCPs onto SWNTs decreased in the presence of cationic surfactant (Cetyltrimethyl Ammonium Bromide, CTAB). This study revealed that the competitive adsorption occurred between CTAB cations and EDC/PPCPs by occupying the available SWNT surface (CTAB adsorption onto SWNTs shows five-regime and maximum adsorption capacity of 370.4 mg/g by applying the BET isotherm). The adsorption capacity of $17{\alpha}$-ethinyl estradiol (EE2) on SWNT showed the decrease of 48% in the presence of CTAB. However, the adsorbed naproxen (NAP) surely increased by forming hemimicelles and resulted in a favorable media formation for NAP partition to increase SWNTs adsorption capacity. The adsorbed NAP increased from 24 to 82.9 mg/g after the interaction of CTAB with NAP. The competitive adsorption for EDC/PPCPs onto SWNTs is likely to be a key factor in the presence of cationic surfactant, however, NAP adsorption showed a slight competition through $CH_3-CH_3$ interaction by forming hemimicelles on SWNT surface.

Effects of chemical modification on surface characteristics and 2,4-dichlorophenol adsorption on activated carbon (활성탄 개질에 따른 표면 특성 변화가 2,4-dichlorophenol 흡착성능에 미치는 영향)

  • An, Sun-Kyung;Song, Won-Jung;Park, Young-Min;Yang, Hyeon-A;Kweon, Ji-Hyang
    • Journal of Korean Society of Water and Wastewater
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    • v.34 no.6
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    • pp.425-435
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    • 2020
  • Numerous chemical modifications on activated carbon such as acidic conditioning, thermal treatment and metal impregnation have been investigated to enhance adsorption capacities of micropollutants in water treatment plants. In this study, chemical modification including acidic, alkaline treatment, and iron-impregnation was evaluated for adsorption of 2,4-dichlorophenol (2,4-DCP). For Fe-impregnation, three concentrations of ferric chloride solutions, i.e., 0.2 M, 0.4 M, and 0.8 M, were used and ion-exchange (MIX) of iron and subsequent thermal treatment (MTH) were also applied. Surface properties of the modified carbons were analyzed by active surface area, pore volume, three-dimensional images, and chemical characteristics. The acidic and alkaline treatment changed the pore structures but yielded little improvement of adsorption capacities. As Fe concentrations were increased during impregnation, the active adsorption areas were decreased and the compositional ratios of Fe were increased. Adsorption capacities of modified ACs were evaluated using Langmuir isotherm. The MIX modification was not efficient to enhance 2,4-DCP adsorption and the MES treatment showed increases in adsorption capacities of 2,4-DCP, compared to the original activated carbon. These results implied a possibility of chemical impregnation modification for improvement of adsorption of 2,4-DCP, if a proper modification procedure is sought.

Separation of Humic Acid Using Polysulfone Ultrafiltration Membrane (폴리설폰 UF막에 의한 부식산 분리)

  • Song, Kun-Ho;Lee, Kwang-Rae
    • Journal of Industrial Technology
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    • v.19
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    • pp.343-350
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    • 1999
  • The separation of humic acid by ultrafiltration was most influenced by pressure difference. when pressure difference increased from latm to 3atm, permeate flux increased from 40% to 60% but rejection rate reduced from 97% to 91% because of adsorption of molecules of humic acid at membrane surface. Since physical adsorption was more dominant than chemical adsorption, adsorption of membrane surface was reduced 50% when slow rate increased at same conditions.

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Removal of Se(IV) by the Fe(III)-impregnated Sea sand - Zeta potential approach to depict the binding between Fe(III) and Sea sand (표면 처리한 Sea sand를 이용한 Se(IV) 제거 - Zeta potential을 통한 Fe(III)간의 반은 메카니즘 연구)

  • 박상원;강혜정
    • Journal of Environmental Science International
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    • v.8 no.2
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    • pp.205-209
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    • 1999
  • Iron hydroxides are good adsorbents for uncomplexed metals, some metal-ligand complexes and many metal oxyanions. However, their adsorption properties of these precipitations are not fully exploited in wastewater treatment operations because of difficulties associated with their separation from the aqueous phase. This study describes experiments in which iron hydroxides were coated onto the surface of ordinary adsorbents(Sea sand) that are very resistant to acids, The coated adsorbents were used in adsorption of oxyanionic metals. The process was successful in removing some anions such as $SeO_3(-II)$ over a wide range of metal concentrations and sorption of oxyanionic metals increased with decreasing pH. Formation of two surface complexes for oxyanionic metals adsorption on iron hydroxides comprise (1) complexation of the free anion by a positively charged surface site, and (2) protonation of the adsorbed anion (or alternatively adsorption of a protonated form from solution) The coated adsorbents are inexpensive to prepare and could serve as the basis of a useful oxyanionic metal removal.

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Adsorption of Hydrogen Sulfide on Surface Modified Activated Carbon using Ferric Nitrate (질산철을 이용하여 표면개질된 활성탄의 황화수소 흡착)

  • Jeong, Moonjoo;Lee, Seongwoo;Kim, Daekeun
    • Journal of Korean Society for Atmospheric Environment
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    • v.31 no.2
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    • pp.173-180
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    • 2015
  • The purpose of this study was to fabricate a ferric nitrate impregnated activated carbon, and the performance for hydrogen sulfide by adsorption was evaluated. Sodium hydroxide was utilized to control pH in the process during generation of ferric hydroxide on the surface of the carbon. Critical mixing duration for generation of ferric hydroxide on the carbon was 48 hrs at pH 1 of the solution, in which the chemical adsorption of hydrogen sulfide was enhanced. The adsorption capacity of the impregnated carbon increased up to 0.10 g hydrogen sulfide/g carbon, which was 4.3 times higher than that of the raw carbon. Presence of FeOOH on the surface of the impregnated carbon was examined by X-ray diffraction.

The Effect on Gas Adsoption Efficiency for Various Surface Characteristics (표면특성에 따른 물맺힘 특성이 가스흡착성에 미치는 영향)

  • 허경욱;신종민
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.8
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    • pp.671-675
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    • 2002
  • The gas adsorption efficiency for various surfaces with three different characteristics has been reviewed. The dimethyl disulfide gas has been used to investigate characteristics of gas adsorption for different surface characteristics such as plasma treated, lacquer coated and untreated. Three different surfaces were evaluated in dry conditions initially and tested at wet surface conditions with spraying water to evaluate the gas adsorption efficiency which usually occurred at defrost cycles. The results show that the gas adsorption of the plasma treated sample has better performance than others. The lacquer coated and untreated samples showed the similar result, but the lacquer coated sample showed a slightly better performance.

Theoretical and Experimental Studies on the Adsorption of N-[(E)-Pyridin-2-ylmethylidene] Aniline, a Schiff Base, on Mild Steel Surface in Acid Media

  • N, Mohanapriya.;M, Kumaravel.;B, Lalithamani.
    • Journal of Electrochemical Science and Technology
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    • v.11 no.2
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    • pp.117-131
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    • 2020
  • The adsorption of N-[(E)-Pyridin-2-ylmethylidene] aniline, a Schiff base, on to mild steel surface in 1M HCl and 0.5 M H2SO4 solutions and the consequent corrosion protection were studied employing weight loss method, electrochemical impedance spectroscopy and potentiodynamic polarization measurements. DFT calculations were performed to investigate its interaction with the metal surface at the atomic level to understand its inhibition mechanism. The adsorption process is well described by the Langmuir isotherm. The thermodynamic parameters indicated that the adsorption is spontaneous and the interaction of the inhibitor at the mild steel surface is mainly through physisorption. The Ra values obtained in AFM studies for the uninhibited and inhibited sample in HCl media respectively are 0.756 and 0.559 ㎛, and that in H2SO4 media are 0.411 and 0.406 ㎛. The lesser roughness values of the inhibited sample shows the adsorption of the molecules onto the mild surface. The inhibition efficiencies were found to improve with concentration of the inhibitor and the maximum efficiency was observed at 400ppm in all the investigation methods adopted. The inhibitor was found to exhibit a higher efficiency in HCl media (95.7%) than in H2SO4 (92.8%). The theoretical and experimental results are found to be in good agreement.

Search for Adsorption Coordination of SiH4 or Al(CH3)3 on Si (001) Surface Using Genetic Algorithm and Density Functional theory (유전 알고리즘과 밀도 범함수 이론을 이용한 Si (001) 표면에서의 SiH4 또는 Al(CH3)3 전구체의 흡착 배위 탐색)

  • Kim, Hyun-Kyu;Kim, Jason;Kim, Yeong-Cheol
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.4
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    • pp.16-22
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    • 2021
  • We search for an appropriate initial adsorption coordination of precursor on surface by using genetic algorithm (GA) and density functional theory. SiH4 and Al(CH3)3 as precursor, and OH-terminated Si (001) as surface are used for this study. Selection, crossover, and mutation as hyperparameters of GA are applied to search for the adsorption coordination of the precursors on the surface as a function of generation. Bond distances between precursors and the surface are used to explain the adsorption behavior of the precursors.