• Journal of the Korean Chemical Society
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• v.60 no.3
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• pp.187-193
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• 2016

In this study, preparation of positively and negatively charged carbon nanotube (CNT)-collagen (CG) hydrogels with pH sensitive characteristic was reported. The positive and negative characteristics of the prepared hydrogels were created by introduction of positively functionalized CNT-NH₂ and negatively functionalized CNT-COOH, respectively, into the collagen hydrogel. The surface charge of CNTs (CNT-NH₂ and CNT-COOH), CG and CNTs/CG hydrogels was measured by Zetasizer. The swelling ratios of CNT-NH₂/CG and CNT-COOH/CG hydrogels in aqueous solution were checked by measuring of weight changes of the hydrogels in the range of pH 2~10. In detail, the positively charged CNT-NH₂/CG hydrogel swelled up to 5% at pH 4 in comparison to the weight at pH 7, while the negatively charged CNT-COOH/CG hydrogel swelled up to 10% at pH 10. The prepared CNT-NH₂/CG and CNT-COOH/CG hydrogels will be very useful as pH sensitive oral drug-delivering systems for gastrointestine (pH ~2) and small intestine (pH ~9), respectively.

• Journal of Soil and Groundwater Environment
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• v.13 no.3
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• pp.8-14
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• 2008

The effects of surfactant types and the ratio of nonionic and anionic surfactants on the washing of diesel contaminated soil were investigated. In batch tests, the nonionic surfactant, which has HLB within 12-13, showed a high diesel removal efficiency and Tergitol 15-S-7 (T15S7) with 20 g/L concentration exhibited the highest removal efficiency of 79-88% among the tested nonionic surfactants. Anionic surfactants, in general, showed lower removal efficiency than nonionic surfactants. In case of mixed surfactant system, the removal efficiency increased with nonionic surfactant concentration. With mixed surfactants of T15S7 and SDS as 3 : 1 ratio, diesel removal was enhanced to 76% with 10 g/L of the mixed surfactants. These results could be used in the selection of proper surfactants for remediation of diesel contaminated soils.

• Journal of the Korean institute of surface engineering
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• v.51 no.5
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• pp.257-262
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• 2018

Cesium lead halide perovskite quantum dots (QDs) have recently emerged as highly promising opto-electronic materials. Despite the relative facile anion exchange reactions in cesium lead halide perovskite QDs, in depth study of the anion exchange reactions such as reaction kinetics are required that can provide insight into the crystal transformation in the cesium lead halide perovskite QDs. Herein, we investigated the anion exchange reaction from $CsPbI_3$ QDs to $CsPbBr_3$ QDs with varying the particle size of the starting $CsPbI_3$ QDs. By characterizing the PL spectra in the anion exchange reaction process, we observed that discontinuous PL peak shifts during I-to-Br anion exchange reaction in starting $CsPbI_3$ QDs over a critical size. Origin of the discontinuous I-to-Br anion exchange kinetics are mainly due to thermodynamically unstable nature of the $CsPb(Br/I)_3$ alloy QDs.

• Journal of the Korean Chemical Society
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• v.42 no.2
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• pp.172-176
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• 1998

An anion exchange resin which has Alizarin Red S (ARS) as functional group was prepared by batch method. The resin is stable in acidic solutions below 0.5 M hydrochloric acid, nitric acid and sulfuric acid and adsorption capacity of Fe(Ⅱ) ion on the resin was larger than other metal ions. The preconcentration and the separation of Fe(Ⅱ) ion from the mixture solution were carried out with the pH 4.5 buffer solution and 0.1 M $HNO_{3}$ as eluents.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.330-332
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• 2003

현대 사회는 인구, 산업, 경제, 활동이 도시에 집중되어 발달되고 있으며, 도시에서의 활동증가로 인한 교통량도 급격히 증가하고 있다. 급격히 증가된 인간의 생활환경 변화로 인한 오염물질의 배출도 역시 증가하여 우리의 주변환경을 심각하게 오염시키고 있다. 대기중에 존재하는 에어로졸 입자는 자연발생원에서 직접 대기중에 배출되는 해염입자, 토양입자 등과 같은 1차 입자(Primary particle)와 주로 연소, 소각 등에 의해 인위적으로 발생된 가스상 물질의 대기중에서 다양한 물리ㆍ화학적인 반응을 통해 생성되는 2차입자(Secondary particle)로 크게 구별할 수 있다. (중략)

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.383-392
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• 1992

(Bakelite-A)-(2,2'-Bipyridine)-Ni(Ⅱ) Nitrate complexes were tested as ion exchanger for nitrate ion-selective electrode. The experimentally observed selectivity and electrode characteristics were relatively in good agreement with the exchanger lipophilicity in the membrane phase. Based on chemical composition, mechanisms for exchange with nitrate ion and internal electrical conduction were postulated. Analytical application to the determination of nitrate were studied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.1020-1026
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• 2011

Seasonal characteristics of water soluble ions in atmospheric particles in Cheonan were studied between 2008 and 2009. $Na^+$, $NH_4^+$ and $NO_3^-$, $SO_4^{2-}$ were the principle cations and anions in both coarse and fine particles. Water soluble ions occupied 24.4%(spring), 33.2%(summer), 40.7%(fall), and 39.6%(winter) of the total mass of coarse particles. In fine particles, 43.0%(spring), 59.7%(summer), 55.4%(fall), and 53.2%(winter) of mass were occupied by water soluble ions. From the factor analysis, 2 and 4 factors were extracted for water soluble ions in coarse and fine particles, respectively. 70.33% of water ions in the coarse particles were estimated from the natural source, but 66.01% in the fine particles were from the anthropogenic source.

• Journal of the Korean Chemical Society
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• v.29 no.2
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• pp.183-190
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• 1985

The elution behaviors of the rare earths was carried out in the iminodiacetic acid solution of various pH as eluent using ion exchange resin. The optimum eluent for the quantitative separation of $Eu^{3+},\;Pr^{3+},\;Ce^{3+}\;and\;La^{3+}$ were 0.0301M IMDA solution of pH 8.00 and 9.00 at 5cm column of the resin Dowex 50${\times}$8 (100-200 mesh). The elution order of the rare earth elements was in order of the atomic number of those elements. From the elution behavior of rare earth and u.v spectrum we found that the complexed rare earth species with IMDA changed according to pH of IMDA.

• Journal of the Korean Chemical Society
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• v.38 no.12
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• pp.891-897
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• 1994

A method has been investigated for the determination of Selenium in Ginseng radix, Ganoderma Lucidum and Garlic using hydride generation atomic absorption spectrometry (HG-AAS). The effects of several acids and sodium tetrahydroborate concentration and their flow rate on the determination of Selenium for the hydride generation were investigated. The method of sample decomposition was also investigated using various mineral acids, such as nitric, perchloric and sulfuric acid in the closed system and foreign ion effects were studied. In the optimum conditions, we obtained calibration curve in the range 0-40 ppb. The analytical data of Garlic, Ganoderma Lucidum and Ginseng radix are 289, 296, 198 ppb, respectively.

• Journal of the Korean Chemical Society
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• v.43 no.6
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• pp.651-655
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• 1999

Xylenol Orange was bonded on an anion-exchange resin (Amberlite lRA 400, in $Cl^-$form) by batch equilibration. The resin was proved to be stable in acidic solutions of about 0.1 M HCl, $HNO_3$ or $H_2SO_4$. Sorption capacities for the metal ions on the Amberlite IRA 400 bonded with xylenol orange have been measured by batch method. The result showed that Fe(III) is higher than any other metals for sorption capacity. The preconcentration and the separation of Fe(lll) from the mixture soIution, therefore, were carried out with the 0.1 M sulfosalicylic acid as an eluent.