• Journal of the Korean Society of Tobacco Science
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• v.29 no.2
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• pp.104-109
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• 2007

The amount of nitrate in the tobacco leaf has been shown to be correlated with the levels of alkaloids and nitrosamines. Also the nitrate content of the tobacco correlated closely with the smoke delivery of nitric oxide and tobacco-specific nitrosamines (TSNAs). These are related with the effect of the reconstituted tobacco leaf(Recon) using the tobacco stems. Adsorption process is gaining interest as one of the effective processes of advanced liquid treatment for liquid containing unnecessary materials. This study is focused on the evaluation of four anion exchangers, a cation exchanger and an activated carbon, as adsorbents for reduction of nitrate anion from Recon extract. In order to analyze the nitrate anion, the IC method used in this work was carried out with a Dionex ICS-2000 system. The effects of dosages of adsorbents and concentration of extract on the removal of nitrate anion were examined. Experimental results showed that for nitrate-anion exchanger, nitrate-cation exchanger and nitrate-activated carbon adsorption system, approximately 70 %, 10 %, and 4 % removal efficiencies were achieved at the Brix 10 and the 20 % addition. Although the activated carbon was little efficient for removal of nitrate ion, the removal of nicotine was very efficient at given conditions.

• Journal of the Korean institute of surface engineering
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• v.52 no.6
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• pp.334-341
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• 2019

Organometal halide perovskite materials have attracted much attention in the photovoltaic and light emitting devices due to the compositional flexibility with AMX₃ formula (A is an organic amine cation; M is a metal ion; X is a halogen atom). The addition of homovalent or heterovalent metal cations to the bulk organohalide perovskites has been performed to modify their energy band structure and the relevant optoelectronic properties by ligand-assisted ball milling. Here, we report CH₃NH₃Pb_1-xM_xBr₃ nanocrystals substituted by metallic cations (M is Sn²⁺, In³⁺, Bi³⁺; x = 0, 0.01, 0.02, 0.05, 0.1, 0.2). Photoluminescence and quantum yield was significantly reduced with increasing metallic cations content. These quenching effect could be resulted from the metal cations that behave as a non-radiative recombination center.

• Korean Journal of Pharmacognosy
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• v.50 no.3
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• pp.198-204
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• 2019

A facile and convenient method was developed for the mass production of epigallocatechin gallate (EGCG) rich green tea extract (Er-GTE). The Er-GTE was successfully obtained from the crude water extract of green tea by the combination of two step purification, i.e., a simple adsorption process on the cation exchange resins (Trilite SCR-B) followed by the chromatography with Diaion HP-20 resins. The green tea extract produced by water extraction under $45^{\circ}C$ was subjected to adsorb on the strongly acidic cation exchange resin, Trilite SCR-B. The eluate passed through the resin was reabsorbed on Diaion HP-20 resin, which was subjected to elute with a mixture of water and alcohol by conventional chromatographical manner. The EGCG content in Er-GTE was estimated above 97% by HP-LC analysis and the newly developed method was regarded as the most suitable and appropriate process for the mass production of epigallocatechin gallate rich green tea extract (Er-GTE).

• Journal of Ecology and Environment
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• v.32 no.4
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• pp.295-304
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• 2009

To understand the properties of soil in Dokdo, we collected soil samples from 12 locations on Seodo and 23 locations on Dongdo, in Dokdo of Gyeongsangbuk-do Province in 2007-2008 and analyzed the soil's physical and chemical characteristics. Sand comprises the largest component (49.37%) of Dokdo soil, followed by silt (40.70%) and clay (9.93%). The soil structure consists mostly of sand loam, followed by loam and silt loam. The pH level of soils from Dokdo varied dramatically among sampling sites and seasons, ranging from 3.36 to 8.02. The total ion content of Dokdo soil also varies greatly among survey places and periods, but in general the total ion content was high in summer when vegetation develops, and low in spring. The exchangeable cation contents of the soil showed low levels in samples where the soil pH was low, including habitats dominated by Agropyron tsukushiense var. transiens and Echinochloa crus-galli, whereas the exchangeable cation contents were high where the organic contents were high, as in habitats dominated by Liriope platyphylla and Artemisia japonica subsp. littoricola. Soil N contents varied greatly among survey sites and higher N contents were found in soil inhabited by Chenopodiaceous plants than in habitats inhabited by other plants. The substantial differences in phosphorus contents among sites were related to excrement of black-tailed gulls. To understand the basic physical and chemical features of the soil on Dokdo, it will be necessary to conduct seasonal and long-term research on soil pH, ion contents, organic contents, N and P, as well as obtaining precise data from samples collected at different depths.

• Journal of Environmental Science International
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• v.20 no.2
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• pp.185-197
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• 2011

Sorption of chlorinated pesticides such as 2,4-dichlorophenoxyacetic acid (2,4-D) and atrazine onto natural clays (montmorillonite and zeolite) modified with cationic surfactant, hexadecyltrimethyl-ammonium (HDTMA) and a natural soil was investigated using batch adsorbers. The clays were transformed from hydrophilic to hydrophobic by the cation exchange between clay surface and HDTMA up to 100% of the cation exchange capacity (CEC). Physicochemical characteristics of the sorbents such as pH, PZC (point of zero charge), organic carbon content ($f_{oc}$), fourier transform infrared spectroscopy (FT-IR), differential thermogravimetric analysis (DTGA) and X-ray diffraction (XRD) were analyzed. Sorption isotherm models such as Freundlich and Langmuir were fitted to the experimental data, resulting Langmuir model ($R^2$ > 0.986) was fitted better than Freundlich model ($R^2$ > 0.973). Sorption capacity ($Q^0$) for 2,4-D and atrazine was in the order of HDTMA-montmorillonite > HDTMA-zeolite > natural soil corresponding to the increase in organic carbon content ($f_{oc}$). The sorption of the pesticides was also affected by pH. The sorption of 2,4-D decreased with the increase in pH, whereas that of atrazine was not changed. This indicated that the sorption capacity ($Q^0$) of 2,4-D and atrazine was not affected by the solution pH because they exist as anionic (deprotonated) forms at pH above pKa. The results indicate that organoclay has a promising potential to reduce chlorinated pesticides in the effluent from golf courses.

• 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.

• The Journal of Engineering Geology
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• v.9 no.2
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• pp.89-100
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• 1999

This study was carried out to assess the physicochemical properties of domestic bentonites and zeolites from Tertiary Formation as the candidate material for a engineered barrier of a radioactive waste repository. Natural bentonite and zeolite samples were collected from nine bentonite mines and six zeolite mines in Yeonil-Gampo area. The commercial products of bentonite and zeolite were obtained from local companies. The collected samples were investigated to study the following physicochemical properties: X-ray diffraction patterns, swelling, cation exchange capacity(CEC), specific surface area, montmorillonite content, pH, organic carbon content, thermal property, microstruciure and chemical composition. Based on the physicochemical properties of bentonite and zeolite, the bentonites from U-41 and G-46 mines and the zeolites from Daedo and Y-1 mines are regarded as the most desirable candidate materials.

• Korean Journal of Environmental Agriculture
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• v.16 no.4
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• pp.327-332
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• 1997

This study was conducted to find out the effect for removal of $NH_3$ gas, one of the offensive odor. The removal efficiencies of $NH_3$ gas through zeolie column increased with the decreased percolation velocity. The effect of zeolite colum in removing $NH_3$ gas was influenced by the water content of zeolite and the added amount of zeolite, but was not influenced by the setting method of zeolite. The $NH_3$ gas removing sequence of saturated cation species on zeolite was in order of Ca->Na->$NH_4$ ->Natural->K-zeolite. Consequently the effect of zeolite on $NH_3$ gas removal efficiency is consided by the water content, added amount and saturated cation of the zeolite.

• Journal of agriculture & life science
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• v.46 no.3
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• pp.19-26
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• 2012

The purpose of this study was to provide basic data for the cultivation of Allium victorialis var. platyphyllum in the area covered with forest vegetation. The populations of A. victorialis var. platyphyllum in Ulleungdo were naturally growing in the communities of Fagus japonica var. multinervis, Acer okamotoanum, Pinus parviflora, Tsuga sieboldii, Pinus densiflora, Pinus thunbergii, Tilia amurensis, and Alnus maximowiczii. On average, the study area of A. victorialis var. platyphyllum population was located in the places of 563 m above sea level, and in the slope area of $27.8^{\circ}$. Soil texture of its inhabitation site mainly consisted of sandy soil, sandy loam, loamy sand, and loam. The depth of the organic layer was 6 cm on average, soil pH 5.4, available phosphate content 18.5 ppm, and cation exchange capacity $18.6cmol_c/kg$. The correlation between the site factors and soil factors by CCA analysis showed that the community of beech tree indicated positive correlation with carbon, nitrogen, sand content, and cation exchange capacity.

• Journal of Magnetics
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• v.20 no.1
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• pp.26-30
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• 2015

The crystallographic and magnetic properties of gallium-substituted cobalt ferrite ($CoGa_xFe_{2-x}O_4$) were investigated. The new material was synthesized using conventional ceramic methods, with gallium substituted for ferrite in the range of x = 0.0 to 1.0, in steps of 0.2. X-ray diffraction and M$\ddot{o}$ssbauer spectroscopy were used to confirm the presence of crystallized particles in the $CoGa_xFe_{2-x}O_4$ ferrite powders. All of the samples exhibited a single phase with a spinel structure, and the lattice parameters decreased as the gallium content increased. The particle size of the samples also decreased as gallium increased. For $x{\leq}0.4$, the M$\ddot{o}$ssbauer spectra of $CoGa_xFe_{2-x}O_4$ could be fitted with two Zeeman sextets, which are the typical spinel ferrite spectra of $Fe^{3+}$ with A- and B-sites. However, for $x{\geq}0.6$, the M$\ddot{o}$ssbauer spectra could be fitted with two Zeeman sextets and one doublet. The variation in the M$\ddot{o}$ssbauer parameters and the absorption area ratio indicated a cation distribution of $(Co_{0.2-0.2x}Ga_xFe_{0.8-0.6x})[Co_{0.8+0.2x}Fe_{1.2-0.4x}]O_4$, and the magnetic behavior of the samples suggested that the increase in gallium content led to a decrease in the saturation magnetization and in the coercivity.