• Journal of Environmental Science International
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• v.22 no.8
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• pp.1009-1017
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• 2013

Perfluorooctanoic acid (PFOA) and perfluorooctyl sulfonate (PFOS) is a new persistent organic pollutants of substantial environmental concern. This study investigated the potential of magnetic ion exchange resin (MIEX$^{(R)}$) as the adsorbent for the removal of PFOA and PFOS from Nakdong River water. In our batch experiments, we studied the effect of some parameters (pH, temperature, sulfate concentration) on the removal of PFOA and PFOS. The results of sorption kinetics on MIEX$^{(R)}$ show that it takes 90 min to reach equilibrium but the economical contact time and dosage were 30 min and 10 mL/L. An increase in pH (pH 6~10) leads to a decrease in PFOA (2.0%) and PFOS (3.6%) sorption on MIEX$^{(R)}$. The sorption of both PFOA and PFOS decreases with an increase in ionic strength for sulfate ion (${SO_4}^{2-}$), due to the competition phenomenon. An increase in water temperature ($8^{\circ}C{\sim}28^{\circ}C$) in water leads to a increase in PFOA (2.8%) and PFOS (4.3%) sorption on MIEX$^{(R)}$. Based on the sorption behaviors and characteristics of the adsorbents and adsorbates, ion exchange and hydrophobic interaction were deduced to be involved in the sorption, and hemi-micelles possibly formed in the intraparticle pores.

• Membrane Journal
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• v.27 no.5
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• pp.406-414
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• 2017

In this study, we have developed pore-filled ion-exchange membranes (PFIEMs) filled with ionomer in a thin polyethylene porous film (thickness = $25{\mu}m$) and investigated the charge-discharge characteristics of the all vanadium redox flow battery (VRFB) employing them. Especially, the degree of crosslinking and free volume of the PFIEMs were appropriately controlled to produce ion-exchange membranes exhibiting both the low membrane resistance and low vanadium permeability by mixing crosslinking agents having different molecular size. As a result, the prepared PFIEMs exhibited excellent electrochemical properties which are comparable to those of the commercial membranes. Also, it was confirmed through the experiments of vanadium ion permeability and VRFB performance evaluation that the PFIEMs showed low vanadium ion permeability and high charge-discharge efficiency in comparison with the commercial membrane despite their thin film thickness.

• Polymer(Korea)
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• v.32 no.1
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• pp.43-48
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• 2008

In this study, the hyper branched poly (styrene-co-divinylbenzene) (PSD) was synthesized by bulk polymerization and the cationic exchanger with high ion exchange capacity was prepared by sulfonation. The structure of hyper branched PSD ion exchanger was investigated by FT-IR, $^1H-NMR$ spectroscopy, and GPC analysis. The molecular weight, viscosity of hyper branched PSD increased with DVB content, which have the maximum values of 9410g/mol and 338 cP, respectively. And the reaction rate also increased with cross-linker content. As DVB content increased, the solubility of PSD decreased having the maximum value of 22 g with 0.1 mol% DVB. The water content and ion exchange capacity of the hyper branched PSD ion exchanger increased with the amount of sulfuric group. Their maximum values were 18.2% and 4.6 meq/g, respectively. The adsorption of copper and nickel ion was completed within 40 min.

• Polymer(Korea)
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• v.26 no.5
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• pp.661-669
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• 2002

The purpose of this research is to absorb and remove sulfur dioxide existing in the air by using ion exchange non-woven fabric. So we found out very appropriate condition of anionic exchange fabric scrubber by measuring amount of SO$_2$ adsorption under the atmosphere that concentration, velocity, and humidity was 100∼200 ppm, 0.6∼1.0 m/sec, and 30∼90 RH%, respectively. Ion exchange capacity of ion exchanger showed the maximum value, 3.75 meq/g at pH 4, and adsorption equilibrium time was the maximum value, 30 h when gas velocity was 0.6 m/sec, moreover, at 80$\^{C}$, adsorption equilibrium time tended to decrease more than 10 h. When concentration was 200 ppm, while reaction speed between SO$_2$ and ligand of fibrous ion exchanger was getting faster, adsorption break point had a tendency to get faster as well. In addition, when relative humidity in the scrubber was 90%, adsorption efficiency was 7.6%/h that seemed to be 30% higher than 4.6%/h coming from the condition that relative humidity had been 30%, and it was totally absorbed under 5 wt% NaOH solution in 5 minutes.

• Analytical Science and Technology
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• v.6 no.3
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• pp.261-265
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• 1993

The ion exchange capacity of DBPDA ion exchanger, {(4,5):(13,14)-dibenzo-6, 9, 12-trioxa-3, 15, 21-triazabicyclo [15.3.1] heneicosa-1(21), 17, 19-triene-2, 16-dione : DBPDA ion exchanger} was 4.2meq/g. The distribution coefficients of alkali and alkaline earth metal ions in the various concentrations of hydrochloric acid were determined using DBPDA ion exchanger. Also alkali and alkaline earth metal ions were separated using DBPDA ion exchanger. From these results the effect of pH of solution and ionic radii of the metal ions on the distribution coefficients of alkali and alkaline earth metal ions were discussed.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.1-4
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• 2003

LDPE/polystyrene cation exchange membranes were prepared through a monomer-sorption method and UV radiation polymerization. The reaction behaviors in the preparation were investigated. The membranes prepared were characterized in terms of physical and electrochemical properties. The membranes exhibited reasonable properties for an ion-exchange membrane with weight gain (Wr) of above 0.3, electrical resistance of below 1.0 Ω $\textrm{cm}^2$ and ion-exchange capacity of 1.8 meq/g-dry membrane. DSC studies and FE-SEM image revealed the formation of a homogeneous membrane. Both the current-voltage and the chronopotentiometric curves of the membranes indicated that LDPE/polystyrene membranes can be properly used at a high current density, and the surface homogeneity of cation-exchange sites in the membrane was comparable to that in a commercial membrane.

• Membrane Journal
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• v.17 no.3
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• pp.210-218
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• 2007

CEDI-BPM(Continuous Electrodeionization-Bipolar Membrane) has advantages due to high ion permselectivity through ion exchange membranes and the production of $H^+$ and $OH^-$ ions on the bipolar membrane surfaces for regeneration of ion exchange resin during electrodeionization operation. In this study, hardness materials were removed by the CEDI-BPM without scale formation and the ion exchange resins were electrically regenerated during the operation. The adsorption characteristic of ion exchange resin surface, the influence of flow rate on the hardness removal and electric regeneration were investigated in the study. The removal efficiency of Ca was higher than that of Mg in the CEDI-BPM, which was related to the high adsorption capacity of Ca on the cation exchange resin. With increasing flow rate, the flux of Ca and Mg was enhanced by the permselectivity of a cation exchange membrane. In the electric regeneration of CEDI-BPM, it was shown that the regeneration efficiency was higher with a lower regeneration potential applied between cathode and anode.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.4
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• pp.269-278
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• 2005

In order to produce only a pH-controlled solution without discharging any unwanted solution, this work has developed a continuous electrolytic system with a pH-adjustment reservoir being placed before an ion exchange membrane-equipped electrolyzer, where as a target solution was fed into the pH-adjustment reservoir, some portion of the solution in the pH-adjustment reservoir was circulated through the cathodic or anodic chamber of the electrolyzer depending on the type of the ion exchange membrane used, and some other portion of the solution in the pH-adjustment reservoir was discharged from the electrolytic system through the other counter chamber with its pH being controlled. The internal circulation of the pH-adjustment reservoir solution through the anodic chamber in the case of using a cation exchange membrane and that through the cathodic chamber in the case of using an anion exchange membrane could make the solution discharged from the other counter chamber effectively acidic and basic, respectively. The phenomena of the pH being controlled in the system could be explained by the electro-migration of the ion species in the solution through the ion exchange membrane under a cell potential difference between anode and cathode and its consequently-occurring non-charge equilibriums and electrolytic water- split reactions in the anodic and cathodic chambers.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.2
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• pp.38-46
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• 2008

Many researchers have reported that many biopolymers making up cell walls of the microorganisms display an ion-exchange property and play a major role in the sorption of the metal ions. Such polymers derived from microbial biomass are potentially useful as biosorbent materials for recovery various metal ions in industrial applications. although synthetic polymers such as ion-exchange resins and chelating resins have been widely used as commercial sorbents. In this study, valuable and commercial biopolymers for metal removal will be introduced.

• Journal of the Korean Wood Science and Technology
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• v.15 no.4
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• pp.12-17
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• 1987

To extract arabinogalactan from larch (Larix Leptolepis), chips immersed with water(20-$90^{\circ}C$) for 1hr, were defiberized by refiner. The liquors were recovered and purified to pure arabinogalactan by ion exchange resin(IRC-50 a. IR-45) or MgO. Additionally the optimal condition in purification with MgO was also investigated. 1. The amounts of solids(crude sugars) and pure arabinogalctan in solids are 8.6-11.3% and 7.3-8.5%(raw material = 100), respectively. 2. Phenolic materials in crude sugars are removed up to 96-89% by ion exchange resin and 94-88% by MgO, while recovery yields of pure arabinogalactan are 81-75% on purification with ion exchange resin and 91-87% on purification with MgO. 3. The optimal conditions of purification with MgO are the addition of 35mg MgO/0.5g of crude sugars, 45 minutes at $70^{\circ}C$, or 25 mg MgO, 30 minutes at $85^{\circ}C$.