• Journal of the Korean Chemical Society
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• v.32 no.4
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• pp.358-370
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• 1988

Several new ion exchange resins have been synthesized from chloromethyl styrene-1,4-divinylbenzene(DVB) with 1%, 2%, 4%, and 10%-crosslinking and macrocyclic ligands of cryptand type by interpolymerization method. The adsorption characteristics and the pH, time, solvents and concentration dependence of the adsorption of metal ions by this resin were studied. The correlation between the separation characteristics of uranium, rare earths and transition metal on the resins and the stability constants of complexes with macrocyclic ligands have been examined. The resins were very stable in both acidic and basic media and have good resistance to heat at $280^{\circ}C$. The $UO_2^{+2}$ aqueous solution are not adsorbed on the resins below pH 3.0, but the power of adsorption of $UO_2^{2+}$ increased rapidly above pH 4.0. The optimum equilibrium time for adsorption of metallic ions was twenty minutes and adsorptive power decreased in proportion to crosslinking size of the resins and order of dielectric constants of solvents used and the selective sequence for metal cations is in the order of $UO_2^{2+},\;Cu^{2+}\;and\;Nd^{3+}$.

• Journal of the Korean Chemical Society
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• v.17 no.5
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• pp.346-352
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• 1973

The quantitative separations of a mixture containing equal amounts of each cation such as Mn(Ⅱ), Cr(Ⅲ), V(Ⅴ), Cu(Ⅱ), Ni(Ⅱ), Co(Ⅱ), and Fe(Ⅲ) are carried out by the elution through $35cm{\times}3.14cm^2$ column of cation exchange resin, $Dowex 50w{\times}12$. The eluents are a mixture of 0.6 M sodium chloride and 0.1 M sodium tartrate (pH = 2.00 and 4.50) for Fe(Ⅲ), V(Ⅴ), Cu(Ⅱ), Ni(Ⅱ) and Co(Ⅱ), and a mixture of 3 M sodium chloride and 0.1 M sodium tartrate (pH = 4.50) or a mixture of 0.7 M sodium chloride and 0.5 M sodium oxalate (pH = 4.50 and 5.00) for Mn(Ⅱ) and Cr(Ⅲ). The subsidiary cations in a standard iron mixture such as V(Ⅴ), Cu(Ⅱ), Ni(Ⅱ), Mn(Ⅱ) and Cr(Ⅲ) are separated together from the large amount of Fe(Ⅲ) through $15cm{\times}3.14cm^2$ column of the resin, $Dowex 1{\times}8$, by elution with the eluent of 4.0 M hydrochloric acid. A small amount of Fe(Ⅲ), however, is eluted together with Cu(Ⅱ). V(Ⅴ), Ni(Ⅱ), Mn(Ⅱ) and Cr(Ⅲ) eluted together are separated quantitatively through $10cm{\times}3.14cm^2$ column of the resin,$Dowex 50w{\times}12$. Cu (Ⅱ) and a small amount of Fe(Ⅲ) are separated quantitatively through $10cm{\times}3.14cm^2$ column of the resin, $Dowex 50w{\times}12$, by the elution with a mixture of 0.6 M sodium chloride and 0.1 M sodium tartrate (pH = 2.00 and 4.50) as an eluent. By the conditions obtained in the separations of the standard iron mixture, Fe(Ⅲ) and all of the subsidiary cations in steel are quantitatively separated.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.1008-1012
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• 2008

Nanoscale zero-valent iron(nZVI) is famous for its high reactivity originated from its high surface area and it has received considerable attentions as one of the latest innovative technologies for treating contaminated groundwater. Due to its fine powdery form, nZVI has limited filed applications. The efforts to overcome this shortcoming by immobilizing nZVI on a supporting material have been made. This study investigated the differences of resin-supported nZVI's characteristics by changing the preparation methods and evaluated its reactivity. The borohydride reduction of an iron salt was proceeded in ethanol/water solvent containing a dispersant and the synthesis was conducted in the presence of ion-exchange resin. The resulting material was compared to that prepared in a conventional way of using de-ionized water by measuring the phyrical and chemical characteristics. BET surface area and Fe content of nZVI-attached resin was increased from $31.63m^2/g$ and 18.19 mg Fe/g to $38.10m^2/g$ and 22.44 mg Fe/g, respectively, by switching the solution medium from water to ethanol/water with a dispersant. The reactivity of each material was tested using nitrate solution without pH control. The pseudo first-order constant of $0.462h^{-1}$ suggested the reactivity of resin-supported nZVI prepared in ethanol/water was increased 61 % compared to that of the conventional type of supported nZVI. The specific reaction rate constant based on surface area was also increased. The results suggest that this new supported nZVI can be used successfully in on-site remediation for contaminated groundwater.

• Applied Biological Chemistry
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• v.15 no.2
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• pp.93-109
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• 1972

Three lots of Chung-Kook-Jang were prepared by the use of 2 strains of Bacillus subtilis and Bacillus natto. For four samples taken from each lot in 12 hrs interval changes of nitrogenous compounds, insoluble protein, water soluble protein, peptides, free amino acids, amino and ammonia nitrogens during Chung-Kook-Jang fermentation, were studied together with the changes of moisture, pH, proteolytic enzyme activity. In addition the average peptide length of the peptides of a Bacillus subtilis lot was determined by the method of molecular sieving using ion exchange resin. The results were as follows: 1. The contents of moisture and total-nitrogen changed little in all samples throughout the fermentation as it would be expected. 2. In all three experimental lots the pH became higher gradually from the initial value of 6.65 to the final $7.5{\sim}7.85$ during the fermentation. Proteolytic enzyme activities, in accordance with this pH change, steadily increased up to $48{\sim}60$ hrs. of fermentation and then slightly decreased, probably affected by the high pH. The most strong proteolytic activity was observed in the experimental Chung-Kook-Jang fermentation lot using the Bacillus subtilis K-27 isolated by the author. 3. The contents of insoluble protein nitrogen in soybeans increased markedly (5%) by the cooking, after steeping 12 hrs in water. During the Chung-Kook-Jang fermentation, however, it decreased from 1/2 to 1/10 of that of the cooked soybeans. 4. The contents of water soluble protein nitrogen (5%) whereas, greatly decreased to the value of 1.0% by the cooking; but little changed further during the fermentation, 5. The total contents (0.25%) of peptides, amino, and ammonia-nitrogens, PAA-N., increased almost double by the cooking and steadily became higher as the fermentation proceeded, reaching finally up to$4{\sim}7%$ in 72 hrs fermentation. 6. The amounts of free amino acids of soybean generally decreased during the processing of cooking, even some of them like glutamic acid were destroyed completely, However in the subsequent Chung-Kook-Jang fermentation for 72 hrs., they showed from several to a few hundreds folds increases depending upon the kinds of amino acids. Valine which was contained in HCl-hydrolyzed steeped or cooked soybeans in amounts $220{\sim}267mg%$ was not detected at all as the free amino acid in all fermented samples. 7. Average peptide length (APL) of all fractions, eluted and fractionated by using the Dowex-50 ion exchange resin column, and fraction collector showed the highest value for the cooked soybean and then decreased as the fermentation proceeded. The APL value of effluent showed the highest in 12 hrs fermented sample, The value decreased thereafter by fermentation.

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.189-194
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• 2013

A sulfonated activated carbon (AC-$SO_3H$) was used as a solid acid catalyst for dehydration of sorbitol to isosorbide and its catalytic performance was compared with the commercial solid acid such as acidic ion exchange resin, Amberlyst-36, and sulfated copper oxide. The catalytic performance with 100% sorbitol conversion and 52% isosorbide selectivity was obtained over AC-$SO_3H$ at 423.15 K. Although AC-$SO_3H$ possessed only 0.5 mmol/g of sulfur content, it showed the similar dehydration activity of sorbitol to isosorbide with Amberlyst-36 (5.4 mmol/g) at 423.15 K. Based on the high thermal and chemical stability of AC-$SO_3H$, one-step reactive distillation, where isosorbide separation can be carried out simultaneously with sorbitol dehydration, was tried to increase the recovery yield of isosobide from sorbitol. The reactive distillation process using AC-$SO_3H$, the turnover number of AC-$SO_3H$ was 4 times higher than the conventional two-step process using sulfuric acid.

• Analytical Science and Technology
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• v.6 no.3
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• pp.255-259
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• 1993

${\beta}$-Carboline alkaloids of Polygala tenuifolia (Polygalaceae), an expectorant, tonic and sedative drude drug, were determined by HPLC. The alkaloids were separated by RP-18 column with gradient elution of 0.01M potassium phosphate buffer(pH=3.5) and acetonitrile and detected at UV 254nm. Two methods for the preparation of alkaloid fraction were compared. One was solvent extraction method using acid and base, and the other was solid phase extraction with ion exchange resin (Amberlyst 15). A more refined HPLC chromatogram was obtained using the solid phase extraction method. The alkaloidal contents in P. tenuifolia determined by this method were : harman $2.8{\times}10^{-3}%$, norharman $1.7{\times}10^{-3}%$, 1-carbomethoxy-${\beta}$-carboline $1.3{\times}10^{-3}%$, 1-carboethoxy-${\beta}$-carboline $1.4{\times}10^{-3}%$ and perlolyrine $3.3{\times}10^{-3}%$, respectively.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.33 no.3
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• pp.189-196
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• 2007

In order to investigate the potential of very low molecular weight hyaluronic acid(oligo HA) as a cosmetic ingredient, we first measured its cytotoxicity in fibroblast, keratinocyte, and SIRC cell lines. For efficacy test, its moisturizing effect and penetration rate were evaluated in an artificial skin system and Caco-2 cells. Oligo HA did not show any cytotoxicity at a concentration of 300 ${\mu}g/mL$ in fibroblasts and 1,000 ${\mu}g/mL$ in keratinocytes but it showed weak proliferation. In vitro ocular test, oligo HA showed negligible cytotoxicity at the maximum concentrations used(2,000 ${\mu}g/mL$) in SIRC cells. In the test of the single and repeated cutaneous applications, oligo HA under occlusive patch did not provoke any cumulative irritation and sensitization. Oligo HA at a concentration of 0.01 % exhibited a more potent moisturizing effect than hyaluronic acid at a concentration of 0.01 %. In the permeability test using artificial skin and Caco-2 cell lines, hyaluronic acid(M.W. $1.1{\times}10^6$) was hardly observed in the down medium of the inserts. On the other hand, oligo HA(M.W. 5,000) was detected in the down medium up to 16.0 % at 6 h in Caco-2 cell culture and up to 90 % at 6 h in an artificial skin system. These results suggest that oligo HA could be useful as an active ingredient for cosmetics.

• Korean Chemical Engineering Research
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• v.49 no.2
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• pp.129-136
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• 2011

Simulated Moving Bed(SMB) process consists of multiple chromatographic columns, which are usually partitioned into four zones. Such a process characteristic allows a continuous binary separations those are impracticable in conventional batch chromatographic processes. Compared with batch chromatography, SMB has advantages of continuity, high purity and productivity. Various researches have been reported for the integration of reaction and recovery during process operation on the purpose of economics and effectiveness. Simulated Moving Bed Reactor(SMBR) is introduced to combine SMB as a continuous separation process and reactor. Several cases of SMBR have been reported for diverse reactions with catalytic, enzymatic and chemical reaction on ion exchange resin as main streams. With an early type of fixed bed using catalyst, SMBR has been developed as SMB using fluidized enzyme, SMB with immobilized enzyme and SMB with discrete reaction region. For simple modeling and optimization of SMBR, a method considering convection only is possible. A complex method considering axial dispersion and mass transfer resistance is needed to explain the real behavior of solutes in SMBR. By combining reaction and separation, SMBR has benefits of lower installation cost by minimizing equipment use, higher purity and yield by avoiding the equilibrium restriction in case of reversible reaction.

• Journal of Korean Society of Forest Science
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• v.90 no.3
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• pp.242-248
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• 2001

Changes in land-use can affect soil organic matter content and fertility. We compared total soil carbon and nitrogen concentrations, soil respiration, and nitrogen availability under three land-use types in central Korea; conversion of old rice field to natural willow-maple (Salix-Acer) forest, conversion of old field to artificial Korean pine (Pines koraiensis) forest, and indigenous oak (Quercus spp.) forest. After 20 years of fallow the area of rice field conversion to forest had higher soil carbon and nitrogen concentrations in the soil depth of 0-10cm and 10-20cm than the areas of field conversion to Korean pine forest and indigenous forest. In general, soil carbon and nitrogen concentrations decreased with soil depth. Organic matter accumulation as a balance of input and decomposition seemed to be higher in the soil of previous rice field, and carbon and nitrogen accumulation was largely confined to the topsoil. Soil respiration rates were greatest at the area of rice field conversion to forest, and appeared to be related to soil carbon and soil moisture. Soil nitrogen availability measured by the ion exchange resin bag method differed significantly among land-use types; soil inorganic nitrogen ($NH_4{^+}+NO_3{^-}$) and ammonium availability were highest in the soil under indigenous oak forest followed by conversion of old field to artificial Korean pine forest and conversion of old field to natural willow-maple forest.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.3
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• pp.165-174
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• 2004

In order to simultaneously vitrify the ion exchange resin(IER) and combustible dry active waste(DAW) generated from Korean nuclear power plants, a vitrification pilot test was conducted using an induction cold crucible melter(CCM) . The energy necessary for startup of the glass using a Ti-ring was evaluated as about 290 kWh. The power supplied from a high frequency generator to melt the glass properly was ranged from 160 to 190 kW without any interruption. When the mixture of the IER and DAW was fed into the CCM, the concentration of CO was lowered up to 1/40 compared to feeding the IER solely. It may be caused by the DAW which can produce about 1.8 times higher heat compared to the IER. When the swelling phenomenon occurred in the glass melt, the concentration of $NO_2$, oxidizing gas, was higher than NO, reducing gas. Total feed amounts of the IER and DAW were 368 and 751 kg, respectively. And then, about 74 of volume reduction factor was achieved.