• 한국조경학회지
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• 제27권5호
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• pp.161-169
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• 2000

In this study, the temporal changes in the chemical characteristics of soil in a reclaimed coastal area, the Shihwa Industrial Complex in the West Coast in Kyung-Gi Province, and the correlations between chemical components were investigated to provide useful information needed for introducing vegetation in the area. The sites were filled with mountain forest soils from 1987 to 1996, and developed into various landuses such as neighbourhood parks, children's parks, buffer greens, pedestrian roads and others. The correlation analyses shoed that pH, organic matter(OM) and available P205 had not been closely related to other chemical parameters such as various cations electro-conductivity(EC) and cation exchange capacity(CEC): especially, pH showed a very low correlation with other factors. The EC turned out to have positive relationships with cations, especially with Na+ ions. There seemed to be fairly good correlations between cations except Ca++ ion. The relation between cations and OM was inconclusive possible because the OM contents in the soils were too low for the analysis. The OM seemed to increase slowly with time and the EC decreased slowly. The salinity and CEC in the original soils decreased rapidly possibly because of leaching. It is believed that there were some external disturbances such as rainfall which had affected the soil properties. The soils sampled in dry season showed a very high salinity. From this it is possible to assume that the rainfall would affect the sol properties significantly. So it is necessary to continue further studies to investigate the impacts of external disturbances such as rainfall on vertical soil profile and temporal variations as well as to delineate correlations between parameters with external disturbances controlled.

• 대한화학회지
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• 제42권4호
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• pp.443-448
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• 1998

용액열량계를 이용하여, 25$^{\circ}C$ 메탄올 용액에서 dibenzo-16-crown-5(DB16C5)의 유도체들과 금속이온과의 착물형성에 관한 열역학적인 파라미터인 log K, ${\Delta}H$, $T{\Delta}S$를 결정하고, dibenzo-16-crown-5의 유도체들을 운반체로 사용하여 벌크액체막과(bulk liquid membrane, BLM) 지지액체막(supported liquid membrane, SLM) 실험을 통하여 금속이온의 이동현상을 관찰하였다. BLM과 SLM에서 운반체로 DB16C5유도체를 사용했을 때 $Ag^+$ 이온이 많이 이동되었고 다른 금속이온들은 약간 이동된 것으로 관찰되었다. 액체막을 통한 그속이온의 이동에서 중요한 파라미터로 작용하는 인자는 리간드의 구조, 곁가지의 길이, 주개원자의 수와 종류, 안정도상수, 리간드의 농도 등을 들 수 있다.

• The Korean Journal of Ceramics
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• 제6권4호
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• pp.380-384
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• 2000

Crystal structure of $Ba_5-5X$Y$_10/3$Nb$_10$O$_30$ was tried to determine by Rietveld analysis using powder X-ray diffraction data. This compound has tetragonal tungsten bronze (TTB) structure with general formula, (Al)$_2$(A2)$_4$(B1)$_2$(B2)$_8$(O1)$_8$(O2)$_8$(O3)$_4$(O4)$_2$(O5)$_4$(O6)$_4$. However, it was difficult to determine the distribution of Ba and Y in Al and A2 sites by the analysis only. Combination of Rietveld analysis and site potentials calculation as well as lattice energy calculations helped to determine the distribution. As the result, it was clarified that $Ba^2+$ cations occupy A2 (pentagonal tunnel site) and $Y^3+$ cations occupy Al (cubic site). The distribution of cations at each site coincides with the distribution estimated by the difference of ionic radii. This supports the formation condition of TTB which was proposed in our previous report. $Ba_5-5X$Y$_10X/3$Nb$_10$O$_30$ shows ferroelectric characteristics. In this compound, remanent polarization decreases slightly with the composition X. On the other hand, the result of crystal structure determination reveals that atomic positions along c-axis for A1, A2, B1 and B2 cations are also decreased with the composition X. This would suggest that the dependence of remanent polarization on composition X is derived by the dependence of atomic coordinates on composition X.

• 분석과학
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• 제10권1호
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• pp.60-65
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• 1997

mono-crown ether(benzo-15-crown-5)와 benzo-15-crown-5를 포함한 bis-(crown ether)s(ethylenediamine bis(4'-formylbenzo-15-crown-5))에 의한 알칼리금속과 알칼리토금속 양이온들의 용매추출을 $25^{\circ}C$, 물-클로로포름계에서 조사하였다. mono-crown ether와 bis-(crown ether)s를 사용한 경우 알칼리금속과 알칼리토금속 양이온들에 대한 추출평형상수($K_e$)와 착물형성상수($K_c$)의 크기 순위는 각각 Ca(II)>Na(I)>Sr(II)>K(I)>Mg(II)>Rb(I)와 Sr(II)>Ca(II)>K(I)>Rb(I)>Mg(II)>Na(I) 순으로 증가하였다. 이들 크기 순위는 금속 양이온의 크기 및 전자밀도효과로서 설명할 수 있었다. 또한 mono-crown ether에 비해서 bis-(crown ether)s를 사용한 경우 금속양이온들에 대한 추출효율이 좋게 나타남을 알 수 있었다.

• 한국광물학회지
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• 제22권3호
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• pp.249-259
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• 2009

본 연구는 황토와 황토에서 분리한 점토(clay fraction)를 이용하여 수용액 내 양이온의 종류와 농도에 따른 점토광물의 분산과 응집의 변화를 알아보고자 하였다. 본 연구를 위하여 사용한 황토는 전남 나주시 동강면 장동리 황토로 지표면으로 부터 90~130 cm 깊이에서 채취하였다. 황토와 황토에서 분리한 점토(< $2\;{\mu}m$) 그리고 이들 시료로부터 결정질 철과 비결정질 철을 제거한 황토와 점토시료를 이용하여 실험을 실시하였다. 이온의 종류와 농도에 따른 점토광물의 저면간격과 물리적 성질의 변화를 알아보기 위하여 4가지 양이온($Na^+$, $K^+$, $Mg^{2+}$, $Ca^{2+}$)과 이들 이온의 농도(0.001 M~1 M)를 변화시켰을 때 광물의 침강속도와 점토광물의 저면간격의 변화를 연구하였다. 장동리 황토의 주 구성광물은 석영이며, 황토로부터 분리한 점토는 카올리나이트, 일라이트, 버미큘라이트로 이루어져 있다. 장동리 황토의 비결정질 철과 결정질 철의 함량은 각각 16.3 mg/kg과 436 mg/kg으로 주로 결정질 철로 이루어져 있다. 이온농도가 다른 4가지 이온을 추가한 수용액에서 구성 입자의 크기가 작은 점토가 황토에 비하여 분산이 더 잘되었다. 황토광물을 코팅하고 있는 결정질 철과 비결정질 철을 제거하기 전과 제거한 후 광물의 분산실험 결과에서 철을 제거한 시료가 분산이 더 잘 일어났으며 이는 코팅된 철 산화물이 광물입자들의 분산을 방해하는 것으로 사료된다. 수용액 중 이온의 종류와 농도가 광물의 분산에 미치는 영향 실험결과에 따르면 첨가한 이온의 농도가 클수록 그리고 양이온 전하량이 클수록 침강속도가 빨랐다. X-선 회절 분석 결과에 따르면 카올리나이트와 일라이트는 양이온의 종류와 농도에 따른 저면 간격의 변화가 없었다. 하지만 버미큘라이트는 일반적으로 +2가 양이온을 첨가한 경우 저면간격이 $14.04\;{\AA}$으로 +1가 양이온의 $13.9\;{\AA}$보다 크게 나타났다. 이는 +2가 양이온들의 수화반경이 +1가 양이온보다 크기 때문으로 사료된다. 따라서 광물에 코팅된 철과 수용에 내의 이온의 종류와 농도가 광물의 분산 및 버미큘라이트와 같은 팽창성 점토광물의 저면간격에 영향을 줄 수 있음을 시사한다.

• 상하수도학회지
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• 제22권5호
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• pp.561-569
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• 2008

We analyzed contents of cations and anions for the domestic bottled drinking water. Results showed that total cation content was 45.81 mg/L and contained 40% of Ca. The content of cations were decreased in the order of Ca>Si>Na>Mg>K. Total anion content was 12.20 mg/L and contained 90% of ${SO_4}^{2-}$ and $Cl^-$. $F^-$ and $NO_{3-}N$ were a little contained. While Si content was reduced 2.3~75.7%(mean value:38.5%) after freezing, Ca content was reduced 45.2% after boiling. It showed that water containing higher Ca content was significantly decreased after boiling. Precipitates formed by freezing and boiling is composed of minerals such as Si and Ca. Compared to minerals from food intake, concentrations of minerals from water intake are expected to be less influenced. It is recommended Bottled Water that contains more than 20 mg/L of Ca(exceeding water-quality standard for turbidity) is safe to drink without thawing and boiling.

• Bulletin of the Korean Chemical Society
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• 제32권11호
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• pp.3979-3990
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• 2011

Eight ionizable nano-baskets of cone 25,26-di(carboxymethoxy)calix[4]arene-crown-3,4,5,6 were synthesized and were verified by $^1H$ and $^{13}C$ NMR spectroscopy, IR spectroscopy and elemental analysis. The competitive solvent extractions of alkali and alkaline earth metal cations were studied using such nano-baskets. The novelty of this study is including three binding units of calixarene's bowl, crown ether's ring and electron-donor ionizable moieties in a unique scaffold to assess the binding tendency towards the cations. The objective of this work is to study the extraction efficiency, selectivity and $pH_{1/2}$ of such complexes. The result of solvent extraction experiments indicated that these compounds were effective extractants of alkali and alkaline earth metal cations. Their selectivities were greatly influenced by the acidity of solution and the conformations of the calixcrown. One conformer was selective to $Na^+$ in pH ${\geq}$ 4, while the other was highly selective to $Ba^{2+}$ in pH 6 and upper.

• 한국산업융합학회 논문집
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• 제19권4호
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• pp.176-184
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• 2016

Electrochemical ion exchange method is expected to be one of the most acceptable techniques for the separation of radioactive cations from nuclear wastewater. In this study a thin film of hexacyanoferrate on nickel surface was derivatized chemically in an aqueous potassium-ferricyanide solution. Electrochemical redox behavior of the nickel hexacyanoferrate(NiHCNFe) film electrode was investigated with the use of cyclic voltammetry potentiostated from -100 to 800 mV versus SCE. The electro-reduction characteristics of the NiHCNFe film were examined in the cobalt solutions. The NiHCNFe ion exchanger was more useful at lower concentration, lower temperature, and pH7 of the cobalt solution. The capacity loss of NiHCNFe was 0.018%/cycle that was less than the average loss of 2~3%/cycle of the convective organic exchanger. The 45~55% of the initial cobalt ions was electro-deposited on the NiHCNFe by using continuous recirculating reactor system. As a result, it was found that the electroactive NiHCNFe films showed better performance than the organic resins for the separation of cobalt ion from the aqueous solutions.

• Journal of Plant Biotechnology
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• 제35권4호
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• pp.337-343
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• 2008

We generated transgenic tomato plants with Arabidopsis thaliana $H^+$/cation exchanger gene (C4X4) by Agrobactrium-mediated transformation. We confirmed transgene copy number and transcription by Southern and Northern blot analyses. The intact CAX4-expressing tomato (Lycopersicon esculentum) fruits contained 63-71% more calcium ($Ca^{2+}$) than wild-type fruits. Moreover, ectopic expression of C4X4 in tomato fruits did not show any significant increase of the four kinds of metallic cations analyzed ($Mg^{2+}$, $Fe^{2+}$, $Mn^{2+}$, and $Cu^{2+})$. The C4X4-expressing tomato plants including their fruits did not show any morphological alternations during whole growth period. These results suggest the enhanced Ca-substrate specificity of CAX4 exchanger in tomato. Therefore, intact CAX4 exchanger can be a useful tool for $Ca^{2+}$ nutrient enrichment of tomato fruits with reduced accumulation of undesirable cations.

• Computers and Concrete
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• 제17권1호
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• pp.53-66
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• 2016

Currently, most of the investigations on chloride diffusion were based on the experiments and simulations concerning single cation type chlorides. Chloride diffusion associated with dual or multi cation types was rarely studied. In this paper, several groups of diffusion experiments are conducted using chloride solutions containing single, dual and multi cation types. A multi-ionic model is also proposed to simulate the chloride diffusion behavior in the experimental tests. The MATLAB software is used to numerically solve the nonlinear PDEs in the multi-ionic model. The experimental and simulated results show that the chloride diffusion behavior associated with different cation types is significantly different. When the single cation type chlorides are adopted, it is found that the bound rates of chloride ions combined with divalent cations are greater than those combined with monovalent cations. When the dual/multi cation type chlorides are adopted, the chloride bound rates increase with the $Ca^{2+}/Mg^{2+}$ percentage in the source solutions. This evidence indicates that the divalent cations would markedly enhance the chloride binding capacity and reduce the chloride diffusivity. Moreover, on the basis of the analysis, it is also found that the complicated cation types in source solutions are beneficial to reducing the chloride diffusivity.