• Polymer(Korea)
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• v.37 no.5
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• pp.592-599
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• 2013

In this study, polyacrylonitrile (PAN)-based porous carbon nanofibers were prepared from PAN polymer solution by electrospinning and KOH activation with various concentrations, and the characterization of pore structures and carbon dioxide adsorption was investigated. Manufactured PAN-based activated carbon nanofibers tend to decrease diameter and increase surface oxygen functional groups depending on the increasing concentration of KOH solution. In addition, according to the results of nitrogen adsorption for pore properties analysis, it indicated increase of the specific surface area in conformity with increasing concentration of KOH solution. Micropore volume of treated activated carbon nanofibers (ANCF) by 4 M KOH was the largest compared with other samples and mesopore volume of treated ANCF by 8 M KOH was the largest volume, respectively. The concentration of KOH effects textural and surface properties, as represented by BET and XPS, which enhance carbon dioxide adsorption capacity at 0 and $25^{\circ}C$.

• Journal of Adhesion and Interface
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• v.14 no.2
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• pp.82-87
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• 2013

Preliminary studies on the synthesis of magnetic nanoparticles including nanoporous carbon materials have been done via a direct carbonization process from resol, ferric nitrate and triblock copolymer F127. The results show that the nanoporous magnetite/carbon ($Fe_3O_4$/carbon) with a low $Fe_3O_4$ content (1 wt%) possesses an ordered 2-D hexagonal (p6mm) structure, uniform nanopores (3.6 nm), high surface areas (up to 635 $m^2/g$) and pore volumes (up to 0.48 $cm^3/g$). Magnetite nanoparticles with a small particle size (10.2 nm) were confined in the matrix of amorphous carbon frameworks with superparamagnetic property (7.7 emu/g). The nanoporous magnetite/carbon showed maximum adsorption amount (995 mg/g) of ibuprofen after 24 h at room temperature. The nanoporous magnetite/carbon was separated from solution easily by using a magnet. The nanoporous magnetite/carbon material is a good adsorbent for hydrophobic organic drug molecules, i.e. ibuprofen.

• Applied Chemistry for Engineering
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• v.26 no.2
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• pp.132-137
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• 2015

BEA-zeolite was modified by alkaline solution to introduce mesoporosity in the crystals and the homogeneous chiral Co(III) salen was immobilized in the mesopores. The dinuclear chiral Co(salen)-$GaCl_3$ catalyst immobilized on mesoporous BEA-zeolite showed high activity for the regioselective ring opening of terminal epoxides by carboxylic acids. Various chiral monoester derivatives could be synthesized with moderate enantioselectivity (47~69 ee%) from racemic epoxides through above reaction. When the chiral (S)-ECH was used as a reactant, it was efficiently resolved by carboxylic acid with a high enantioselectivity in the presence of heterogenized chiral salen catalyst, and the ring opened product afforded optically pure monoester epoxide (R)-GB (up to 98 ee%) through the ring closing in the basic solution by elimination of HCl. The heterogeneous catalyst could be fabricated easily, and the catalytic activity was retained for several times reuse without any further regeneration step.

• Membrane Journal
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• v.22 no.1
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• pp.35-45
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• 2012

We prepared the highly ordered nano-wires of polypyrrole, polyaniline conductive polymers and polypyrrole/ polyaniline conductive copolymers by templating the anodic aluminum oxide (AAO) porous membrane, in which pore diameter was 20 nm, 100 nm and 200 nm. Those conductive polymers were grown from pore inner surface of AAO membrane forming hollow tubes and then wire structures were formed after 3 hour polymerization. By removing AAO membrane templates using sodium hydroxide solution, the conductive polymer nano-wires were successfully obtained, of which diameter and length were close to the ones of nano-pores in AAO membrane template. Crystallinity and thermal stability of the conductive polymer nano-wires were higher than irregular ones that prepared by solution polymerization. Furthermore, the electrical resistance of conductive polymer nano-wires were reduced by about 4~60% compared with that of the irregular polymers prepared by solution polymerization.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.04b
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• pp.45-47
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• 1997

정밀여과 및 한외여과에 의해 단백질 등과 같은 거대분자 물질을 분리정제할 경우 피할 수 없는 문제점은 막에 의해 분리된 거대부자들이 막표면에 쌓이는 농도분극(concentration polarization)현상과 이 누적된 거대분자가 막과의 상호작용에 의해 막표면 또는 막세공 내에 비가역적으로 침적되는 막오염(membrane fouling)현상이 일어난다는 점이다. 특히 막표면 또는 막세공 내에 분리대상 물질이 비가역적으로 침적되어 발생되는 막오염은 상대적으로 가역적 침적 과정인 농도분극보다 제어 또는 억제가 어려워 최근의 막분리 분야 연구의 상당 부분이 막오염 유발요인의 해석, 막오염을 효율적으로 제어 또는 억제하기 위한 방법의 연구에 집중되고 있다. 본 연구에서는 단백질 용액의 정밀여과시 단백질 변성이 막오염에 미치는 영향을 체계적으로 규명하기 위한 연구의 일환으로서 BSA를 분리대상 물질로하여, BSA용액을 미리 기계적 Shear(펌프 및 sonification), 열, 화학적 방법(pH 및 변성제)으로 변성시킨 후, 이 용액을 대상으로 회분식 정밀여과 실험을 수행하여 단백질 응집체 형성이 막투과량 감소에 미치는 영향을 실험적으로 검토하였으며, 각각의 막투과량 감소 특성을 아래의 4가지 blocking filtration law로서 해석하였다: complete blocking law, intermediate blocking law, standard blocking law, cake filtration law.

• Applied Chemistry for Engineering
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• v.8 no.5
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• pp.756-762
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• 1997

The experiment was carried out to fabricate alumina membrane which has a cylindrical pore structure by anodizing aluminium plate in sulfuric acid solution with the electrochemical technique. The aluminium plate for anodizing was prepared by the pretreatment process such as chemical, electro-polishing and thermal treatment. The pore size distribution and the film thickness of alumina membrane were investigated by the implementation of scanning electron microscope(SEM) and BET method. The results show that the oxide film has a geometrical structures like a Keller model and that the membrane has a uniform pore distribution. The pore size and the oxide film thickness are dependent on the anodizing process variables such as the electrolyte concentration, the reation temperature and the anodizing current density.

• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.608-614
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• 1999

The counter-diffusion of aromatic compounds such as coronene and tetra-phenylporphine by injection of acetone or tetra-phenylporphine solution was studied on aluminas and silica-alumina used widely as catalysts support. The counter-diffusivity was determined from simulation results by using the counter-diffusion model employing ideal adsorbed solution theory. The counter-diffusivities of aromatic compounds in the catalyst supports were ranged in ${\sim}10^{-15}m^2/sec$ in the desorption process by the injection of excess acetone. In the counter-diffusion process with tetra-phenylporphine solution which have similar concentration with adsorption solution, the counter-diffusivities of coronene were also ${\sim}10^{-15}m^2/sec$, and that of tetra-phenylporphine into pores were determined as ${\sim}10^{-11}m^2/sec$. The counter-diffusivities of coronene desobed from the adsorbent were significantly redyced in comparison with the effective diffusivities when there is counter-diffusion flux. The values mainly depended on the existence of counter-diffusion flux, but not concerned with the species and amount of desorbates.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.384-388
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• 2006

The adsorption ability of polar and toxic substance was greatly enhanced by treating activated carbon with acid solution and impregnating iron, copper, or silver by using in 0.1 M $FeSO_4{\cdot}7H_2O,\;CuSO_4{\cdot}5H_2O,\;AgNO_3$ 300 mL per activated carbon 50 g. Physical and chemical properties of the metal impregnated activated carbons were measured using specific surface area, pore volume and size distribution, scanning eletron microscope(SEM), adsorption isotherm. When activated carbon was treated with acid, the quantity of impregnated metal increased about 1.3 times since the micropores were converted to mesopores or macropores. Both the physical absorption by micropores and chemical absorption by metal ions could be achieved simultaneously with the metal impregnated activated carbon because the capacity of micro pores did not change even after metal ions were impregnated.

• Membrane Journal
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• v.17 no.3
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• pp.219-232
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• 2007

The polyethersulfone(PES)-titanium oxide($TiO_2$) hybrid membranes were prepared by immersion precipitation phase inversion method. The casting solution for the preparation of $PES-TiO_2$ hybrid membrane was provided by adding $TiO_2$ nano particles into the basis polymer solution of 14 wt% and 20 wt% PES/N-methyl-2-pyrrolidone(NMP). The $TiO_2$ loading [wt% ($TiO_2/NMP$)] in eating solution was varied from 0 to 60 wt%. Membrane performance and morphological change of the resulting $PES-TiO_2$ hybrid membranes were discussed in aspect of $TiO_2$ loading, by viscosity, coagulation value and light transmittance of the casting solution, measurement of tensile strength, pore size and contact angle, surface and cross sectional SEM images of the hybrid membrane, and ultrafiltration experiments using the hybrid membrane. According as increase of $TiO_2$ loading in the casting solution, viscosity is increased and coagulation value becomes lower, therefore the thermodynamic instability of the casting solution is increased. It is found that when $TiO_2$ loading is increased, 1) precipitation rate becomes faster while instantaneous demixing is maintained, 2) pure water flux, membrane pore size and compaction stability of the resulting membranes are increased, 3) tensile strength and contact angle are decreased. Dead-end ultrafiltration of bovine serum albumin(BSA) solution using the hybrid membrane shows that membrane performance(flux of BSA solution) enhanced up to 7 times compared with the results obtained using the pure PES membrane(not containing $TiO_2$ particle), due to the increase of hydrophilicity.

• Journal of the Korea Concrete Institute
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• v.14 no.1
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• pp.100-109
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• 2002

Significant damage to concrete results from the intrusion of corrosive solutions, for example, dissolved chlorides corrode reinforcing steel and cause spatting. Effectively blocks the penetration of these solutions will eliminate or greatly reduce this damage and lead to increased durability. This study is to investigate the effects of pozzolanic admixtures, fly ash and silica fume, and a blast furnace slag on the chloride ion penetration of concretes. The main experimental variables wore the water-cementitious material ratios, the types and amount of admixtures, and the curing time. And it is tested for the porosity and pore size distributions of cement paste, chloride ion permeability based on electrical conductance, and 180-day ponding test for chloride intrusion. The results show that the resistance of concrete to the penetration of chloride ions increases as the w/c was decreased, and the increasing of curing time. Also, concrete with pozzolans exhibited higher resistance to chloride ion penetration than the plain concrete. The significant reduction in chloride ion permeability(charge passed) of concrete with pozzolans due to formation of a discontinuous macro-pore system which inhibits flow. It is shown that there is a relationship between chloride ion permeability and depth of chloride ion penetration of concrete, based on the pore structure (porosity and pore size distributions) of cement paste.