• Journal of the Korean Applied Science and Technology
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• v.26 no.3
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• pp.328-334
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• 2009

Recently, much interest on mesoporous carbon has been shown in their use for both hydrogen and methane storage and as an electrode material for electric double layer capacitors. The mesoporous active carbons by ion exchange were prepared and physical properties such as specific surface area and pore structure of active carbon were investigated using BET. In this study, active carbons with mesopore fraction of $60{\sim}90%$ were obtained. The Fe/Ca-exchanged active carbons showed a greater mesoporosity compared with Fe-exchanged carbons. The mean mesopore size in active carbons using Ca- and Fe-exchange was about $5.5{\sim}6.0nm$ and was approximately 1nm higher than that of the Fe-exchanged active carbon.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.590-594
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• 2011

An aminocarboxy aspartic acid-bonded silica (Asp-Silica) stationary phase was synthesized using L-aspartic acid as ligand and silica gel as matrix. The standard protein mixtures were separated with prepared chromatographic column. The effects of solution pH, salt concentration and metal ion on the retention of proteins were examined, and also compared with traditional iminodiacetic acid-bonded silica (IDA-Silica) column. The results show that Asp-Silica column exhibited an excellent separation performance for proteins. The retention of proteins on Asp-Silica stationary phase was consistent with electrostatic characteristic of cation-exchange. The stationary phase displayed typical metal chelate property after fixing copper ion (II) on Asp-Silica. Under competitive eluting condition, protein mixtures were effectively isolated. Asp ligand showed better ion-exchange and metal chelating properties as compared with IDA ligand.

• Applied Chemistry for Engineering
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• v.27 no.6
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• pp.633-638
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• 2016

In this study, we used three kinds of commercially available cation, anion, and mixed-ion exchange resins to separate radioactive ions from a polluted water containing Cs, I, and other radioactive ions. The experiment was conducted at a room temperature with a batch method, and a comparative analysis on the decontamination ability of each resin for the removal of Cs and I was performed by using different quantities of resins. The concentration was analyzed using ion chromatography and the ion exchange resin product from company D showed an overall high ion exchange ability. However, for most of the experiments when the amount of ion exchange resin was decreased, the decontamination ability of the resins against mass increased. When the mass of company D's cation exchange resin was small, the ion exchange ability against Cs and I ions were measured as 0.199 and 0.344 meq/g, respectively. When the mixed ion exchange resin was used, the ion exchange ability against I ions was measured as 0.33 meq/g. All in all, company D's ion exchange resins exhibited a relatively higher ion exchange ability particularly against I ions than that of other companies' exchange ions.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.929-932
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• 2012

The classical molecular dynamics simulation was used to study the phase transition of gold nanoparticles under confinement using Sutton-Chen (SC) potential. Metal gold nanoparticles with different number of atoms are subject to replica exchange molecular dynamics simulation for this purpose. The simulation showing the solidto-liquid melting temperature largely remains unaffected by confinement, while the confinement induces characteristic pre-melting at very low temperature depending on atom number in nanoparticles.

• Polymer(Korea)
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• v.31 no.3
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• pp.247-254
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• 2007

Heterogeneous anion exchange membranes were prepared by compression molding for the recovery of sulfate ion from waste water. The swelling ratio, transport number, and ion exchange capacity of the heterogeneous anion exchange membranes were increased and their electrical resistances were decreased as the amount of ion exchange resin content in the matrix was raised. The tensile strength of the heterogeneous anion exchange membrane was decreased with increasing the amount of ion exchange resin in the LLDPE. The tensile strength for the LDPE heterogeneous membrane containing 30 wt% anion exchange resin showed the highest value. The water content increased with increasing amount of ion exchange resin in the membrane. Moreover the highest transport number of the membrane was 0.86. The electrical resistance of LDPE matrix membrane with 50 wt% resin showed $46.5{\Omega}{\cdot}cm^2$. Current efficiency of electrodialysis for sulfate ion showed the highest value at the current density of $125 mA/cm^2$ in 0.5 mol/L sulfuric acids solution.

• Membrane Journal
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• v.30 no.1
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• pp.21-29
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• 2020

In this study, we have established the optimum design condition of pore-filled anion-exchange membrane for all-vanadium redox flow battery (VRFB). From the experimental results, it was proven that the membrane design factors that have the greatest influence on the charge-discharge performance of VRFB are the ion exchange capacity, the porosity of substrate film, and the crosslinking degree. That is, the ohmic loss and the crossover of active materials in VRFB were shown to be determined by the above factors. In addition, two methods, i.e. reducing the ion exchange capacity at low crosslinking degree and increasing the crosslinking degree at high ion exchange capacity, were investigated in the preparation of pore-filled anion-exchange membranes. As a result, it was found that optimizing the crosslinking degree at sufficiently high ion exchange capacity is more desirable to achieving high VRFB charge-discharge performances.

• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.909-913
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• 2018

A hydrocarbon trap (HT) plays an important role of controlling vehicle emissions in the so-called cold emission period by holding hydrocarbons until three way catalysts (TWCs) are thermally activated. In this study, we have investigated the adsorption characteristics of cation (H, La, K, and Ag)-exchanged ZSM-5 zeolites for hydrocarbons (propylene, n-butane, and toluene) by DFT (density functional theory)-based computational chemistry. Cation exchange is to improve the hydrothermal stability of zeolites and their adsorption capacity, thereby rendering cation-exchanged zeolites promising materials for HT. The idea of cluster approximation makes the calculation of adsorption energies superbly efficient in computation. The results showed that Ag-exchanged ZSM-5 would be the best for the adsorption of all three adsorbates, without often encountered Ag oxidation in experiments. Besides, the hydrothermal stability of La-exchanged ZSM-5 was confirmed from the change of geometrical parameters by cation exchange, and it showed good adsorption capacity for propylene and toluene. Hydrogen-exchanged ZSM-5 was also good for hydrogen adsorption, but had poor hydrothermal stability.

• Journal of Environmental Science International
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• v.18 no.12
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• pp.1411-1416
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• 2009

Several adsorbents were tried to remove the selenium ions from industrial wastewater and the following ascending order of the adsorption performance for the selenium at pH 9 was observed: cation exchange resin < chelate resin < zeolite < brown marine algae < granular activated carbon < anion exchange resin. Initial concentration of selenium(146 mg/L) in industrial wastewater was reduced to 63 mg/L of selenium at pH 9 by neutralization process. The maximum uptake of Se calculated from the Langmuir isotherm with anion exchange resin was 0.091 mmol/g at pH 10 and that with granular activated carbon was 0.083 mmol/g at pH 6. The affinity coefficients of Se ion towards anion exchange resin and granular activated carbon were 3.263 L/mmol at pH 10 and 0.873 L/mmol at pH 6, respectively. The sorption performance of anion exchange resin at the low concentration of Se, namely, was much better than that of granular activated carbon. The Se ions from industrial wastewater throughout neutralization process and two steps of adsorption using anion exchange resin was removed to 97.7%.

• Bulletin of the Korean Chemical Society
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• v.22 no.1
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• pp.53-58
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• 2001

Sulfonated poly(phenylene sulfide) (SPPS) polymers were prepared by sulfonation of poly[methyl[4-(phenylthio) phenyl]sulfonium trifluoromethanesulfonate] (PPST) with fumic sulfonic acid (10% $SO_3-H_2SO_4$) and demethylation with aqueous NaOH solution. The equilibrium constants of ion exchange reactions between alkali metal cations ($Li^+,\;Na^+,\;and\;K^+$) and SPPS ion exchanger in organic solvents such as tetrahydrofuran (THF) and dioxane were measured. The equilibrium constants of ion exchange reactions increased as the polarity of the solvent increased, and the reaction temperature decreased. The equilibrium constants of the ion exchange reaction ($K_{eq}$) also increased in the order of $Li^+,\;Na^+,\;and\;K^+$. To elucidate the spontaneity of the exchange reaction in organic solvents, the enthalpy, entropy, and Gibbs free energy were calculated. The enthalpy of reaction ranged from -0.88 to -1.33 kcal/mol, entropy ranged from 1.42 to 4.41 cal/Kmol, and Gibbs free energy ranged from -1.03 to -2.55 kcal/mol. Therefore, the exchange reactions were spontaneous because the Gibbs free energies were negative. The SPPS ion exchanger and alkali metal ion bounding each other produced good ion exchange capability in organic solvents.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.1067-1070
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• 2012