• Journal of the Korean Chemical Society
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• v.41 no.11
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• pp.612-638
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• 1997

The methods of separation and recovery of rare earth elements in monazite sand have been studied by the ion exchange chromatography. Both of cation and anion exchange resin were used as ion exchange resins and the solutions of EDTA, DTPA, IMDA and Ln-EDTA were used as eluents. The H+, Zn2+, Fe3+, Al3+, Cu2+, and NH4+ forms of cation exchange resin were used as retaining ions. Ln-EDTA solution was loaded on the EDTA form of anion exchange resin and separated. The Ln-EDTA solution was also used as an eluent for a selective separation of one element from the rare earth mixture solution. The size effects of resin column, the elution mechanism for the various elution types and the separation of a large amount of rare earths were studied.

• Journal of the Korean Electrochemical Society
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• v.2 no.4
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• pp.183-189
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• 1999

A study on the destruction of organic cation and anion exchange resins by electro-generated Ag(II) as a mediator was carried out to develop the ambient-temperature aqueous process, known as Ag(II)-mediated electro-chemical oxidation (MEO) process, for the treatment of a large quantity of spent organic ion exchange resins as the low and Intermediated-level radioactive wastes arising from the operation, maintenance and repairs of nuclear facilities. The effects of controllable process parameters such as applied current density, temperature, and nitric acid concentration on the MEO of organic ion exchange resins were investigated. The cation exchange resin was completely decomposed to $CO_2$. The current efficiency increased with a decrease in applied current density while nitric acid concentration and temperature on the MEO of cation exchange resin did not affect the MEO. On the other hand, anion exchange resins were decomposed to CO and $CO_2$. The ultimate conversion to CO was about $10\%$ regardless of temperature. The destruction efficiencies to $CO_2$ were dependent upon temperature and the effective destruction of anion exchange resin could be obtained above $60^{\circ}C$.

• Journal of the Korean Chemical Society
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• v.17 no.6
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• pp.416-423
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• 1973

Formation of the complexes of alkaline earth metal ions with malonate and o-phthalate ions in aqueous, ethanol-water and acetone-water solutions (20% by volume) was studied at room temperature by the equilibrium ion exchange technique. This technique involved the measurements of distribution of radioactivity between cation exchange resin(Ion Exchange Resin CGC 241) and solution phases after the radioactive metal ions were equilibriated with the cation exchange resin in the presence of malonate or o-phthalate ions of varying concentrations. The pH of the solutions was controlled to 7.2~7.5, and the ionic strength of the solutions was kept at 0.10~0.11. The results of the present study indicated that the alkaline earth metal ions formed one-to-one complexes with the dibasic organic acids in all solvent systems examined. The present study showed that the relative stabilities of the complexes increased in the order: $Ba^{++}\;<\;Sr^{++}\;<\;Ca^{++}$ complexes. It was also observed that the relative tendency of the o-phthalate ion for the complex formation was somewhat greater than that of malonate ion in each solvent system. Furthermore, it was noted that the complexes were formed more readily in the mixed solvent than in the aqueous solution.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.6
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• pp.533-544
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• 2021

Ion exchange (IX) performance on the exchanger bed is essentially evaluated for the generation of ultrapure water in electronics and chemical industries and for the corrosion control in nuclear power plants. The breakthrough characteristics of IX bed with multi-component were investigated with both cation- and mixed-IX beds of H- and ETAH-form for four kinds of cation exchange resins by using the combined solution of ethanolamine (ETA) and ammonia (NH₃) at trace NaCl. Unlike major components (ETAH⁺ and NH₄⁺ ), the phenomena of breakthrough and overshooting at bed outlet were not observed by Na⁺ over the test period (> 3 times theoretical exchange capacity of IX bed). The breakthrough from H-form resin bed was sequentially reached by ETAH⁺ and NH₄⁺, while the overshooting was observed for ETAH⁺ at the breakthrough of NH₄⁺. NH₄⁺ was 51.5% higher than ETAH⁺ in terms of the relative selectivity determined with the width of breakthrough zone. At the increased concentration of Na⁺ at bed inlet, the selectivity and the overshooting were decreased and increased, respectively. Na⁺ leakage was higher from ETAH-form resin bed and was not identical for four kinds of cation-exchange resins, which may be reduced by improving the intrinsic property of IX resin.

• Journal of the Korean Chemical Society
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• v.33 no.2
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• pp.232-237
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• 1989

The elution mechanism of rare earth elements in cation exchange resin which was substituted with $NH_4^+,\;Zn^{2+}\;or\;Al^{3+}$ as a retaining ion had been investigated. Rare earths or rare earths-EDTA complex solution was loaded on the top of resin bed and eluted with 0.0269M EDTA solution. When the rare earth-EDTA complex was adsorbed on the $Zn^{2+}\;or\;Al^{3+}$ resin form, retaining ion was complexed with EDTA and liberated rare earths was adsorbed in the resin again. Adsorbed rare earths in resin phase could be eluted by the complexation reaction with EDTA eluent. On $NH_4^+$ resin form, the rare earth-EDTA complex which had negative charge could not adsorbed on the cation exchange resin because the complexation reaction between $NH_4^+$ and EDTA was impossible. So the elution time was much shorter than in $Zn^{2+}\;or\;Al^{3+}$ resin form. When the rare earths solution was loaded on the $Zn^{2+},\;Al^{3+}$ resin form bed, rare earths was adsorbed in the resin and the retaining ion was liberated. Adsorbed rare earths in resin bed was exchanged by EDTA eluent forming rare earths-EDTA complex, and eluted through these processes. On $NH_4^+$ resin form, rare earths loaded was adsorbed by exchange reaction with $NH_4^+$. As the EDTA eluent was added, rare earths was liberated from resin forming negatively charged rare earth-EDTA complex and eluted without any exchange reaction. So the elution time was greatly shortened and there was no metallic ion except rare earths in effluent. When the $Zn^{2+}\;and\;Al^{3+}$ was used as retaining ion, the pH of efflent was decreased seriousely because the $H^+$ liberated from EDTA molecule.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.812-825
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• 2019

Two dolomite samples mined from the different mines were calcined using a batch-type microwave kiln ($950/60min^{\circ}C$) to produce $CaO{\cdot}MgO$. The hydration of the $CaO{\cdot}MgO$ samples shows different reactivity. MgO was separated by reacting with a strong acid cation exchange resin using the reactivity of the hydration properties of light dolomite ($CaO{\cdot}MgO$). Calcium ($Ca-(R-SO_3)_2$) was separated from the prepared $CaO{\cdot}MgO$ by the cation exchange resin ($CaO{\cdot}MgO:R-SO_3H=1:12mass%$). High purity MgO (higher than 94 mass %) with unburned $CaCO_3$ (1~2 mass %) was obtained by the separation process. The separated MgO was heated at $950^{\circ}C$ for 60 minutes to afford high purity MgO with MgO content higher than 96%. And High-grade $CaCO_3$ was prepared from the reaction with calcium adsorbed resin ($Ca-(R-SO_3)_2$) and NaOH, $CO_2$ gas.

• Bulletin of the Korean Chemical Society
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• v.6 no.4
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• pp.225-228
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• 1985

The absorptions of Fe(Ⅲ), Tb(Ⅲ), Tl(Ⅰ), Ce(Ⅲ), Th(Ⅳ), and $UO_2^{2+}$ ions into the Dowex 50W-X2, 100-200 mesh resin were investigated by spectrophotometry to understand the abnormal strong absorption behavior of cations to cation exchange resins in concentrated HClO4. The distribution coefficients increase in the order : Tl(Ⅰ) < Fe(Ⅲ) < Tb(Ⅲ)∼Ce(Ⅲ) < $UO_2^{2+}$< Th(Ⅳ) and the order is interpreted in terms of the ratio of charge-to-ionic radius. The mole ratios of increment of $ClO_4^-$ ion absorption to metal ion absorption showed the same order as the distribution coefficients, which indicates that the electrostatic association between $ClO_4^-$ ion and metal ion plays a major role in the strong absorption.

• Membrane Journal
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• v.25 no.5
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• pp.431-439
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• 2015

The study was evaluated and compared to commercial heterogeneous membrane in order to make cation exchange membrane set up the optimal preparing condition. The research findings show that ion exchange resin was added more than 40 wt% in order to show chemical properties of HPVDF higher than commercial heterogeneous membrane. But ion exchange resin was added less than 40 wt% in order to show mechanical properties of HPVDF higher than commercial heterogeneous membrane. According to conditions above, Electrical resistance was $1.83{\Omega}{\cdot}cm^{-1}$, water uptake was 79%, ion exchange capacity was 1.60 meq/g, and burst strength was 0.97 MPa. Also The TDS remove efficiency was measured by approximately 40%.

• Journal of Pharmaceutical Investigation
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• v.38 no.1
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• pp.9-14
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• 2008

Cation exchange resin complex of amlodipine free base has been investigated to improve the stability and dissolution profile. The complex was prepared by reacting amlodipine solution with activated cation exchange resin, and amlodipine content in the complex was 31.6% calculated by HPLC determination. Its product was not physical mixture but the complex formed by ionic bond, which was identified by microscope system, differential scanning calorimetry and X-ray diffractometry. Each tablet containing amlodipine free base(I) and its complex(II) was prepared for the accelerated stability test ($40^{\circ}C$, 75%RH) and dissolution test in the pH 1.2 buffer solution and purified water media. Dissolution patterns of formulation II in both media were similar to those of $Norvasc^{(R)}$ tablet, but the pattern of formulation I in purified water was different. After 6 months storage under stability test, amlodipine content of formulation I, II and $Norvasc^{(R)}$ tablet were $99.3{\pm}1.2%,\;98.9{\pm}1.4%\;and\;83.9{\pm}3.4%$, respectively. While amlodipine free base was unstable at the condition, its complex was not only significantly stable, but also similar in the dissolution pattern. These results suggest the usefulness of complex as a stable carrier for amlodipine free base.

• Korean Journal of Food Science and Technology
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• v.32 no.3
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• pp.610-617
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• 2000

The indigestible dextrin with high indigestible fraction was prepared by treating the enzyme hydrolysate of pyrodextrin with ethanol or strongly acidic cation exchange resin(UBK 530). Optimum conditions of ethanol treatment for preparing the indigestible dextrin from $\alpha-amylase$ and amyloglucosidase treated hydrolysate were determined based on the indigestible fraction, dietary fiber content, and yield. Ethanol was added 5-fold by weight to 30%(w/w) enzyme hydrolysate, and the mixture was kept at room temperature for 3 hr. Low molecular weight saccharides containing glucose and high molecular weight saccharides were separated by strongly acidic cation exchange resin. While initial enzyme hydrolysate by $\alpha-amylase$ and amyloglucosidase showed 43.6% of DPI(glucose) and 51.1% of DP4+(maltotetraose and over), the indigestible dextrin collected to 50% of initial enzyme hydrolysate by treatment of cation exchange resin showed 7.1% of DPI(glucose) and 91.2% of DP4+(maltotetraose and over). In conclusion, 44.5% of indigestible fraction of initial enzyme hydrolysate increased to 78.9% after separation of low molecular weight saccharides.