• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.606-615
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• 1990

The purity of CeO$_2$, Sm$_2$O$^{3+}$ and La2O$^{3+}$ have been determinated by separating the impurity of rare earth-elements in those oxides with anion exchange resin and measuring the absorbance of the separated element with MTB. 1 ml of the mixture solution containing each 1 mg/ml of Y$^{3+}$, Yb$^{3+}$, Eu$^{3+}$, Sm$^{3+}$, Nd$^{3+}$, Pr$^{3+}$, Ce$^{4+}$and La$^{3+}$ is loaded in top layer of anion exchange resin column, Amberlite CG400 and separated with the mixture solution of the various concentration of methyl alcohol and nitric acid as an eluent. Using the result, the impure rare earth elements in pure CeO$_2$, Sm$_2$O$^{3+}$ and La$_2$O$^{3+}$ are determinated.

• Korean Chemical Engineering Research
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• v.51 no.5
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• pp.615-621
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• 2013

Membrane characterization methods for aqueous redox flow batteries aqueous RFBs were modified for non-aqueous RFBs. The modified characterization methods, such as ion exchange capacity, transport number, permeability and single cell test, were carried out to evaluate commercial membranes in non-aqueous electrolyte. It was found that columbic efficiency and energy efficiency in a single cell test were dependent on the ion selectivity of commercial anion exchange membranes. Neosepta AHA anion exchange membrane showed the anion transport number of 0.81, which is a relatively low ion selectivity in non-aqueous electrolyte, however, exhibited 92% of coulombic efficiency and 86% of energy efficiency in a single cell test. It was also found that a porous membrane without ion selectivity is suitable for a non-aqueous redox flow battery at a high current density.

• Journal of the Korean institute of surface engineering
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• v.49 no.2
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• pp.159-165
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• 2016

The hydrogen has been recognized as a clean, nonpolluting and unlimited energy source that can solve fossil fuel depletion and environmental pollution problems at the same time. Water electrolysis has been the most attractive technology in a way to produce hydrogen because it does not emit any pollutants compared to other method such as natural gas steam reforming and coal gasification etc. In order to improve efficiency and durability of the water electrolysis, comprehensive studies for highly active and stable electrocatalysts have been performed. The platinum group metal (PGM; Pt, Ru, Pd, Rh, etc.) electrocatalysts indicated a higher activity and stability compared with other transition metals in harsh condition such as acid solution. It is necessary to develop inexpensive non-noble metal catalysts such as transition metal oxides because the PGM catalysts is expensive materials with insufficient it's reserves. The optimization of operating parameter and the components is also important factor to develop an efficient water electrolysis cell. In this study, we optimized the operating parameter and components such as the type of AEM and density of gas diffusion layer (GDL) and the temperature/concentration of the electrolyte solution for the anion exchange membrane water electrolysis cell (AEMWEC) with the transition metal oxide alloy anode and cathode electrocatalysts. The maximum current density was $345.8mA/cm^2$ with parameter and component optimization.

• Korean Journal of Materials Research
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• v.28 no.11
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• pp.633-639
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• 2018

In anion exchange membrane fuel cells, Pd nanoparticles are extensively studied as promising non-Pt catalysts due to their electronic structure similar to Pt. In this study, to fabricate Pd nanoparticles well dispersed on carbon support materials, we propose a synthetic strategy using mixed organic ligands with different chemical structures and functions. Simultaneously to control the Pd particle size and dispersion, a ligand mixture composed of oleylamine(OA) and trioctylphosphine(TOP) is utilized during thermal decomposition of Pd precursors. In the ligand mixture, OA serves mainly as a reducing agent rather than a stabilizer since TOP, which has a bulky structure, more strongly interacts with the Pd metal surface as a stabilizer compared to OA. The specific roles of OA and TOP in the Pd nanoparticle synthesis are studied according to the mixture composition, and the oxygen reduction reaction(ORR) activity and durability of highly-dispersed Pd nanocatalysts with different particles sizes are investigated. The results of this study confirm that the Pd nanocatalyst with large particles has high durability compared to the nanocatalyst with small Pd nanoparticles during the accelerated degradation tests although they initially indicated similar ORR performance.

• Journal of the Korean institute of surface engineering
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• v.55 no.3
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• pp.180-186
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• 2022

The production of hydrogen via water electrolysis (i.e., green hydrogen) using renewable energy is key to the development of a sustainable society. However, most current electrocatalysts are based on expensive precious metals and require the use of highly purified water in the electrolyte. We demonstrated the preparation of a non-precious metal catalyst based on CuCo₂O₄ (CCO) via simple electrodeposition. Further, an optimization process for electrodeposition potential, solution concentration and electrodeposition method was develop for a catalyst-substrate integrated electrode, which indicated the highly electrocatalytic performance of the material in electrochemical tests and when applied to an anion exchange membrane water electrolyzer.

• Journal of Environmental Science International
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• v.9 no.4
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• pp.319-323
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• 2000

Nitrate-selective ion exchange resin which have bulky tertiary amine as functional group have been synthesized by the reaction of chloromethylated polystyrene-divinylbenzene copolymer and the corresponding tertiary amine [$NR_3=NE_{t3} 1, N{(C_2 H_4 H_3)}_32]$in ethanol, while commercial resin has $NMe_3$ as functional group. The fundamental properties such as bulk density, water content, appearance index, exchange capacity, effective size, uniformity coefficient of synthesized anion exchange resin (1) have been measured. The ion exchange resin (1) and (2) exhibited the better selectivity for nitrate than sulfate in both batch and continuous column experiments.

• Membrane and Water Treatment
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• v.3 no.4
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• pp.211-219
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• 2012

To enhance the efficiency of water treatment and reduce the extent of membrane fouling, the membrane separation process is frequently preceded by other physico-chemical processes. One of them might be ion exchange. The aim of this work was to compare the efficiency of natural organic matter removal achieved with various anion-exchange resins, and to verify their potential use in water treatment prior to the ultrafiltration process involving a ceramic membrane. The use of ion exchange prior to ceramic membrane ultrafiltration enhanced final water quality. The most effective was MIEX, which removed significant amounts of the VHA, SHA and CHA fractions. Separation of uncharged fractions was poor with all the resins examined. Water pretreatment involving an ion-exchange resin failed to reduce membrane fouling, which was higher than that observed in unpretreated water. This finding is to be attributed to the uncharged NOM fractions and small resin particles that persisted in the water.

• Journal of Life Science
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• v.11 no.6
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• pp.561-567
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• 2001

To isolate and purify fibrinolytic active substance from Sarcodon aspratus(N $H_4$)$_2$S $O_4$ precipitation, DE52 anion exchange column chromatography, Sephacryl-S 200gel filtration chromatography and Mono S cation FPLC were carried out and the characterizations of the purified enzyme were investigated. The bound active fraction on DE52 anion exchange column chromatography were eluted with 0.2 M NaCI and the fibrionlytic enzyme was purified after following Sephacryl-S200 gel fitration chromatography and Mono S cation EPLC. The specific activity of purified enzyme was 55.2 U/mg protein and increased 11.3 fold comparing crude extract and the yield was 49.5%. 12% SDS-PAGE electrophoresis and gel filtration chromatography revealed that Sarcodon aspratus fibrionloytic enzyme was highly purified and had 29.300 Da molecular weight. Enzyme activity of the purified fibrinolytic enzyme from Sarcodon aspratus was increased on higher pH and was stable until pH 10.5. On temperature dependent stability, the enzyme activity was decrease sharply but remained 25% relative activity on 8$0^{\circ}C$. This enzyme activity was inhibited by heavy metal ion, C $U^{2+}$ and $Co^{3+}$ with 68% and 38%, respectively. And also, the enzyme activity was inhibited with $Ca^{2+}$ chelator EDTA and serine protease inhibitor PMSF. These results from this study suggested that the fibrinolycit enzyme from Sarcodon aspratus is a serine protease and the enzyme activity was increased by $Ca^{2+}$ or $Mg^{2+}$ ion.n.ion.n.

• Analytical Science and Technology
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• v.13 no.5
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• pp.584-591
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• 2000

The separation of Nd from the simulated $U_3Si/Al$ spent fuel solution with sequential two-step anion exchange separation has been studied. To prepare the simulated $U_3Si/Al$ spent nuclear fuel, unirradiated $U_3Si/Al$ whose composition consists of small $U_3Si$ particle dispersed in an Al matrix with Al cladding was dissolved with a mixture of 4 M HCl and 10 M $HNO_3$ and 8 or 15 fission product elements were added to the dissolved solution. The trace amount of silica in the solutions was removed by evaporating to dryness with HF and the U was adsorbed on the first anion exchange resin. Neodymium can be purely isolated from the fission product elements with a methanol-nitric acid eluent using the second anion exchange resin. A large excess of Al didn't influence on the elution velocity of Nd, but reduced the eluted contents of Nd, Al, Eu, Gd, Sm and Sr, A large amount of Al was removed first from the column with 3 mL of loading solution (0.8 M $HNO_3$/99.8% MeOH) before Nd elution by the eluent [0.04 M $HNO_3$-99.8% MeOH(1:9)]. The recovery of Nd was more than 94%, regardless of Al contents. Taking the 9 to 13 mL fraction of eluate was effective to purely isolate Nd.

• Korean Journal of Food Science and Technology
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• v.35 no.5
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• pp.791-796
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• 2003

Polyphenol oxidase isoforms were purified from the lotus roots using 50% acetone precipitation, conventional chromatographies of Q-Sepharose and hydrophobic interaction, and high performance liquid chromatographies of Mono-Q and Superdex 75 gel-filtration. Molecular mass of a purified PPO isoform (LPIII-2) was determined to be 56 kDa using gel-filtration chromatography. The active form of LPIII-2 appeared to bea heterodimer, as purified LPIII-2 on SDS-PAGE gel showed two bands that were determined to be 28 kDa and 26 kDa. To further characterize PPO, partially purified PPO isoforms (LP-II, LP-III) were obtained from Q-Sepharose anion-exchange chromatography. In substrate specificity, the partially purified PPO isoform LP-II showed a high affinity to catechol, while LP-III showed a high affinity to pyrogallol. The optimum pH of LP-II and LP-III was pH 7.0. Interestingly, the partially purified PPO isoforms showed high activities at low temperatures $(0{\sim}5^{\circ}C)$, and as temperatures rose, the activities decreased. Both PPO isoforms were stable at $40^{\circ}C$ and were inactivated by incubation at $60^{\circ}C$ for 40 min.