• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3362-3366
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• 2013

A simple and quick separation technique for selenite in natural water was developed using $TiO_2$@$SiO_2/Fe_3O_4$ nanoparticles. For the synthesis of nanoparticles, a polymer-assisted sol-gel method using hydroxypropyl cellulose (HPC) was developed to control particle dispersion in the synthetic procedure. In addition, titanium butoxide (TBT) precursor, instead of the typical titanium tetra isopropoxide, was used for the formation of the $TiO_2$ shell. The synthesized nanoparticles were used to separate selenite ($Se^{4+}$) in the presence of $Se^{6+}$ or selenium anions for the photocatalytic reduction to $Se^0$ atom on the $TiO_2$ shell, followed by magnetic separation using $Fe_3O_4$ nanoparticles. The reduction efficiency of the photocatalytic reaction was 81.4% at a UV power of 6W for 3 h with a dark adsorption of 17.5% to the nanoparticles, as determined by inductively coupled plasma-mass spectrometry (ICP-MS). The developed separation method can be used for the speciation and preconcentration of selenium cations in environmental and biological analysis.

• Bulletin of the Korean Chemical Society
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• 제35권2호
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• pp.392-396
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• 2014

New organic-inorganic composite of 2,4-dihydroxybenzophenone (BP-1) encapsulation into dodecylbenzenesulfonate (DBS) modified layered double hydroxide (LDH) was successfully prepared. The surface, structural, thermal and absorption properties of the BP-1/DBS-LDH nanohybrid was characterized by BET analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TG) and diffuse reflectance UV-Vis absorbance spectra (DRUV-vis). The interlayer configuration of composite and the adsorption mechanism of BP-1 on MgAl-DBS-LDH were discussed. It was suspected that DBS anions located in the form of monolayer arrangement with a $75^{\circ}$ anti parallel angle between dodecylbenzenesulfonate chain axis. The diffuse reflectance UV-Vis absorbance results revealed that the UV absorbing wavelength of BP-1/DBS-LDH evidently extends to about 400 nm, which shows that the BP-1/DBS-LDH has the potential application as a UV absorber.

• Bulletin of the Korean Chemical Society
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• 제29권9호
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• pp.1774-1780
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• 2008

New PVC based polymeric membrane electrodes (PME) and coated glassy carbon electrodes (CGCE) based on synthesized Schiff base complexes of Co(III); [Co(Salen)$(PBu_3)_2$]$ClO_4$, [Co($Me_2$Salen)$(PBu_3)_2$]$ClO_4$, [Co(Salen)$(PBu_3)H_2O$]$ClO_4$; as anion carriers for potentiometric determination of $ClO_4\;^-$were studied. The PME and also CGCE electrodes prepared with [Co(Me2Salen)$(PBu_3)_2$]$ClO_4$ showed excellent response characteristics to perchlorate ions. The electrodes exhibited Nernstian responses to $ClO_4\;^-$ ions over a wide concentration range with low detection limits ($1.0 {\times} 10^{-6}\;mol\;L^{-1}$ for PME and $9.0 {\times} 10^{-7}\;mol\;L^{-1}$ for CGCE). The electrodes possess fast response time, satisfactory reproducibility, appropriate lifetime and, most importantly, good selectivity toward $ClO_4\;^-$ relative to a variety of other common inorganic anions. The potentiometric response of the electrodes is independent of the pH in the pH range 2.5-8.5. The proposed sensors were used in potentiometric determination of perchlorate ions in mineral water and urine samples. The interaction of the ionophore with perchlorate ions was shown by UV/Vis spectroscopy.

• 한국대기환경학회지
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• 제24권1호
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• pp.100-107
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• 2008

The objective of this study was to quantitatively estimate PM-10 source contribution in Gumi City, Korea. Ambient PM-10 samples were collected by a high volume air sampler, which operated for 84 different days with a 24-h sampling basis, from June 14,2001 though May 19, 2003. The filter samples were analyzed for determining 13 inorganic elements, 3 anions, and a total carbon. The study has intensively applied a receptor model, the PMF (Positive Matrix Factorization) model. The results from PMF modeling indicated that a total of seven sources were independently identified and each source was contributed to the ambient Gumi City from secondary sulfate (34%), motor vehicle (26%), soil relation (5%), field burning (3%), industrial relation (3%), secondary nitrate (22%), and incinration (7%) in terms of PM-10 mass, respectively.

• Bulletin of the Korean Chemical Society
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• 제11권2호
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• pp.109-114
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• 1990

The anionic transition metal hydrides $(HW(CO)_4P(OMe)_3\;^-,\;HW(CO)_5\;^-,\;HCr(CO)_5\;^-,\;HFe(CO)_4\;^-)$ react with transition metal alkyl $(CpMo(CO)_3(CH_3)$ to yield $CH_4\;and\;CH_3CHO$ in addition to the inorganic products $(CpMo(Co)_3\;^-$, etc.). The reaction of these anionic metal hydrides with CpMo(CO)3{CH2CH(CH2)2} may lead to an elucidation of the reaction mechanisms involved; the organic product distributions are among $CH_4,\;CH_2\;=\;CHCH_2CH_3$, and $CH_3CH(CH_2)_2$, depending upon the anionic metal hydride used. These anionic metal hydrides also are reported to undergo a hydride-halide exchange reaction with organic halides; therefore, these similar reactions have been compared in terms of leaving group ability $(CpMo(CO)_3\;^-\;vs.\;Br^-)$ and the mechanistic pathways.

• 한국세라믹학회지
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• 제39권11호
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• pp.1090-1096
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• 2002

몬모릴로나이트군의 벤토나이트(BEN)와 첨가제로서 풀림제 및 음이온 계면활성제를 배합하여 6종의 수팽윤성 BEN 유동성 개질제(WSB-1~WSB-6)를 제조하였다. 제조한 WSB의 평균입경, 입자형태, 용액점도, 수팽윤성 및 첨가제에 따른 점도를 각각 측정하였고, WSB의 유동학적 거동을 레오메타를 이용하여 조사하였다. WSB-1의 점도는 pH가 낮을수록 BEN의 평균입경이 작을수록 각각 증가하였고, 풀림제로서 $Na_2CO_3$를 처리한 WSB-2의 점도가 가장 높게 나타났다. 이 결과는 WSB에 포함된 BEN 입자가 edge-to-face의 구조로 재배열이 일어나기 때문으로 해석할 수 있다. 또한 WSB에 풀림제 및 음이온 계면활성제가 포함된 WSB-4, WSB-5 및 WSB-6은 전단력에 따라 점도의 변화가 거의 없는 졸(sol)상으로 존재하지만, 음이온 계면활성제로서 Tetrasodium Pyrophosphate(TSPP)를 첨가한 WSB-3의 경우는 전단력에 따른 점도가 1000배의 차이가 남으로서 요변성(thixotropy)을 나타내었고, 이 결과로부터 TSPP의 음이온이 WSB-3에 포함된 BEN 입자의 edge에 배열된다고 설명할 수 있다.

• 한국환경농학회지
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• 제19권2호
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• pp.110-115
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• 2000

동진강 수계의 수질현황을 파악하기 $1994{\sim}1998$년 까지 $4{\sim}9$월에 월 1회에 걸쳐 5개년간 조사한 결과를 요약하면 다음과 같다. 월별로는 빗물에 의한 희석효과로 7, 8월에 수질이 가장 양호하였으며, 4월이 다소 불량하였으나 수도생육 피해 한계농도에는 미치지 못하는 수준이었다. 지점별 수질현황은 생활하수 유입지인 정읍천과 지천의 폭이 좁은 원평천의 무기성분 함량이 높았으며 동진천 상류지역에서 가장 양호하였다. 연도별 현황은 '94년 이후 '95년까지는 수질이 악화되는 경향을 보였으나 '95년 이후로는 각 성분 함량이 낮았지는 등 점점 양호해지고 있으며 COD함량으로 볼 때 특히, 정읍천의 수질이 개선되고 있음을 알 수 있었다. 양이온과 음이온의 총당량온 4월에 가장 높았고 7, 8월에 가장 낮았으며 양이온/음이온의 당량비는 5월에 높았고 7월이 가장 낮았으며 지점에 따라서는 총당량은 정읍천, 원평천, 동진천 하류, 중류, 상류의 순위였으며 양이온/음이온 총당량 비율은 원평천이 상대적으로 작은 수치를 보였지만 지역간 큰 차이는 보이지 않았다. 수질 중 각 성분 상호간의 상관관계를 보면, 대개의 성분 상호간에 유의성이 높게 나타났으나, $NO_4\;^--N$는 대개의 성분과 유의성이 없었고, $PO_4\;^{3-}-P$도 COD, $NH_4\;^+-N$, $NO_3\;^--N$, $SO_4\;^{2-}$과는 유의성을 보이지 않았다.

• 공업화학
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• 제16권5호
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• pp.595-602
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• 2005

이온성 액체는 $100^{\circ}C$ 이하에서 액체로 존재하는 이온성 염으로 낮은 휘발성, 비가연성, 높은 온도에서의 액체상 안정성, 유기물과 무기물에 대한 높은 용매화 능력, 높은 전기 전도성 등 독특한 화학적, 물리적, 전기적 특성을 갖고 있어 신 개념의 매체로 주목받고 있다. 특히, 이용 목적에 따라 양이온과 음이온을 다양하게 조합하여 그 특성을 변화시킬 수 있어서 디자이너 용매(designer solvent)라고도 불린다. 이온성 액체는 기존 화학산업을 비롯한 에너지, 재료, 전자 등 광범위한 산업분야에서 필수적으로 사용되는 휘발성 유기용매를 대체하여 환경유해물질의 배출을 원천적으로 방지하면서 반응선택성과 반응성을 향상시킬 수 있는 green media로 기대되고 있다. 본 총설에서는 이온성 액체의 구조, 특성, 응용분야와 연구동향에 대해 기술하였다.

• Environmental Engineering Research
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• 제12권1호
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• pp.16-20
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• 2007

Toxicity of metal plating wastewater was evaluated by using acute toxicity tests on Daphnia magna. To identify toxicants of metal plating wastewater, several manipulations such as solid phase extraction (SPE), ion exchange and graduated pH adjustment were used. The SPE test had no significant effect on baseline toxicity, suggesting absence of toxic non-polar organics in metal plating wastewater. However, anion exchange largely decreased the baseline toxicity by 88%, indicating the causative toxicants were inorganic anions. Considering high concentration of chromium in metal plating wastewater, it is thought the anion is Cr(VI) species. Graduated pH test showing independence of the toxicity on pH change strongly supports this assumption. However, as revealed by toxicity confirmation experiment, the initial toxicity of metal plating wastewater (24-h TU=435) was not explained only by Cr(VI) (24-h TU = 725 at $280\;mg\;L^{-1}$). Addition of nickel($29.5\;mg\;L^{-1}$) and copper ($26.5\;mg\;L^{-1}$) largely decreased the chromium toxicity up to 417 TU, indicating antagonistic interaction between heavy metals. This heavy metal interaction was successfully predicted by an equation of 24-h $TU\;=\;3.67\;{\times}\;\ln([Cu]\;+\;[Ni])\;+\;79.44$ at a fixed concentration of chromium.

• The Korean Journal of Physiology
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• 제30권2호
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• pp.279-288
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• 1996

Chronic exposure to cadmium impairs various renal tubular functions, including organic acid (anion) secretion. To investigate the mechanism of cadmium-induced alterations in the organic anion transport system, kinetics of p-aminohippurate (PAH) uptake was studied in renal cortical basolateral membrane vesicles (BLMV) isolated from cadmium-intoxicated rats (adult male Sprague-Dawley). Cadmium intoxication was induced by subcutaneous injections of $CdCl_{2}$ (2 mg Cd/kg per day) for 3 weeks. The renal plasma membrane vesicles were prepared by Percoll gradient centrifugation. The vesicular uptake of $^{14}C$-PAH was determined by rapid filtration technique using Millipore filter. Cadmium intoxication resulted in a marked attenuation of $Na^{+}$-dependent, ${\alpha}$-ketoglutarate (${\alpha}$KG)-driven PAH uptake with no changes in $Na^{+}$ and ${\alpha}$KG-independent transport component. Kinetic analysis indicated that Vmax, but not Km, of the $Na^{+}$-dependent, ${\alpha}$KG-driven component was reduced. A similar reduction of $Na^{+}$-dependent, ${\alpha}$KG-driven PAH uptake was observed in normal membrane vesicles directly exposed to inorganic cadmium in vitro, and this was accompanied by an inhibition of both $Na^{+}$-dependent ${\alpha}$KG uptake and ${\alpha}$KG-PAH exchange activity. These results indicate that during chronic exposure to cadmium, free cadmium ions liberated in the proximal tubular cytoplasm directly interact with the basolateral membrane and impair the active transport capacity for organic anions, most likely due to an inhibition of both $Na^{+}$-dicarboxylate cotransporter and dicarboxylate-organic anion antiporter activities.