• 한국대기환경학회지
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• 제12권4호
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• pp.389-398
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• 1996

In order to understand the relative importance of various pathways leading to the production and transformation of aerosols under different atmospheric conditions, the behavior of atmospheric aerosols have been investigated using a high volume tape sample in Seoul for a week period during August 1990. The concentrations of anion $(SO^{2-}_4, NO^-_3, CI^-)$ and cation $(Ca^{2+}, Na^+, NH^+_4)$ species of aerosol samples were analyzed to identify the ionic composition of aerosols and to estimate their relative contributions to aerosol formation. The concentrations of aerosol species were calculated by a multiple regression model. The results of our calculations indicate the existence of various chemical species such as $(NH_4)_2SO_4, Na_2SO_4, CaSO_4, NH_4NO_3, NaNO_3, Ca(NO_3)_2, NH_4Cl$, and NaCl salts. According to our calculations, the most dominant species of aerosol was $(NH_4)_2SO_4$ with the mean concentration of 23.3 $/mu g/m^3$ (66.9%). The proportion of different componts with aerosol (e.g., $NH_4NO_3$ and $NH_4Cl$) was strongly affected by temperature, relative humidity, and partial presure of gases.

• 한국산학기술학회논문지
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• 제3권2호
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• pp.156-159
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• 2002

이온교환은 이온성 물질을 제거하는 가장 신뢰성 있는 단위공정일 뿐만 아니라 재사용의 측면에서 매우 경제적이다. 특히 이온교환은 토양화학 분야에서 지난 한 세기 동한 수많은 연구가 진행되어 왔으며, 여러 가지 수처리 공정에 널리 이용되고 있다. 이온의 선택도는 이온의 수화반경과 용액의 농도, 이온의 원자가에 따라 좌우된다. 본 연구는 양이온 평형실험과 칼럼실험을 통해 이온들의 선택도 순서와 바탕음이온에 따른 특성을 조사하였다. 양이온의 선택성은 농도가 낮을수록, 이온의 원자가가 높을수록 증가하였다. 평형실험의 양이온 선택도 순서는 $H^+$ < $K^+$ << $Cu^{2+}$ < $Co^{2+}$ < TEX>$Ca^{2+}$ << $Ce^{3+}$ 이며, 칼럼흡착에서도 선택도 순서는 동일하였다.

• 자원리싸이클링
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• 제27권4호
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• pp.44-49
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• 2018

몰리브덴은 알칼리용액에서는 $MoO{_4}^{2-}$로 존재한다. 수용액의 pH 2와 6 사이의 범위에서는 $MoO{_4}^{2-}$와 수소이온간의 축중합반응에 의해 다양한 동종다중음이온이 형성된다. 몰리브덴용액의 pH가 2 이하의 범위에서는 동종다중양이온이 형성되나 무기산의 농도가 증가함에 따라 무기산의 음이온과 반응하여 이종다중음이온이 형성된다. pH 6 이하의 용액에서 몰리브덴의 농도분포는 몰리브덴과 무기산의 종류와 농도에 의존한다. 따라서 용매추출과 이온교환자료를 해석하기 위해서는 강산용액에서 몰리브덴 화학종을 규명할 필요가 있다.

• Bulletin of the Korean Chemical Society
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• 제14권1호
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• pp.123-127
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• 1993

New lipophilic Crown-4 compounds of 16-membered rings containing furan (neutral carrier,I), tetrahydrofuran (neutral carrier,II) and lithium complex of the latter (neutral carrier,III) have been synthesized and tested as the active sensors for lithium ion in poly(vinyl chloride) (PVC) membrane electrode, in the presence and absence of an anion excluder, tetrakis(4-chloro-phenyl)borate (KTClPB), 2-nitrophenyl phenyl ether (NPPE), tris(2-ethylhexyl)phosphate (TEHP), o-nitrophenyl octyl ether (NPOE), dioctyl adipate (DOA), bis(2-ethylhexyl)adipate (BEHA), di-n-octylphenyl phosphonate (DOPP) were used as plasticizing solvent mediators. The electrode response function had a nearly Nernstian slope of 54-61 mV per decade (25$^{\circ}$C) within the concentration range of $10^{-1}-10^{-4}$ M LiCl and the detection limits for all electrodes were ca. $5{\times}10^{-4}$ M. The response time of the electrode was faster at the higher lithium concentration and the response of the electrode was stable for longer than 6 months. The sensor membranes exhibit improved response times and increased lifetimes as compared to the system described earlier.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.115-116
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• 2023

This study aims to investigate and improve the carbon dioxide sequestration capability and the mechanical properties of non-hydraulic low calcium silicate cement especially designed for CO₂ reaction and ordinary Portland cement subjected to the carbonation curing facilitating pH swing method. Nitric acid (HNO₃) was utilized as an liquid for the mixing of cement paste to enhance the initial dissolution of Ca ions from the cements by promoting low pH environment and prevent the direct precipitation of Ca with the anion, owing to the high solubility of Ca(NO₃)₂ in water. The results presented that the higher the concentration of HNO₃, the higher the compressive strength and CO₂ sequestration (until 0.1 M). Ca dissolution caused by the harsh acid attack onto the anhydrous cement particle lead to the higher carbonation reaction degree, forming abundant CaCO₃ crystals after the reaction. However, cement paste mixed with excessively high concentration of HNO₃ presented deterioration due to the too harsh pH environment and abundant NO₃- ions which are known to retard the reaction of cement.

• Natural Product Sciences
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• 제5권2호
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• pp.80-84
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• 1999

Peroxynitrite is a cytotoxic intermediate produced by the reaction between the superoxide anion radical and nitric oxide. Flavonoids (afzelin, quercitrin and quercetin 3-O-sambubioside), and chlorogenic acid and its methyl ester obtained from leaves of loquat (Eriobotrya japonica) have recently been shown to scavenge 1,1-diphenyl-2-picrylhydrazyl radical and to inhibit lipid peroxidation in mouse liver homogenate. The aim of this study is to investigate the inhibitory effects of the above components on peroxynitrite produced stimulated by 3-morpholinosydnonimine (SIN-1) to produce superoxide anion radical and nitric oxide at the same time. In addition, the present study tests whether or not the components directly scavenge peroxynitrite itself. The results showed that the components with the aromatic ortho-dihydroxyl groups (catechol) were more potent inhibitors of peroxynitrite formation by SIN-1. In particular, the methyl ester form of chlorogenic acid showed the most potent inhibition. At $5\;{\mu}M$ concentration, the order of minimizing peroxynitrite formation were : methyl chlorogenic acid > quercitrin > quercetin 3-O-sambubioside > chlorogenic acid > afzelin. Authentic peroxynitrite was directly scavenged by the components in a manner similar to peroxynitrite formation by SIN-1. In particular, when compared with penicillamine as a positive control, methyl chlorogenate was as effective in inhibiting peroxynitrite formation and approximately 2 times more effective in scavenging an authentic peroxynitrite. These results demonstrate therefore, that components extracted from the leaves of Eriobotrya japonica effectively scavenged peroxynitrite.

• The Korean Journal of Physiology and Pharmacology
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• 제21권4호
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• pp.371-376
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• 2017

The caudal subnucleus of the spinal trigeminal nucleus (medullary dorsal horn; MDH) receives direct inputs from small diameter primary afferent fibers that predominantly transmit nociceptive information in the orofacial region. Recent studies indicate that reactive oxygen species (ROS) is involved in persistent pain, primarily through spinal mechanisms. In this study, we aimed to investigate the role of xanthine/xanthine oxidase (X/XO) system, a known generator of superoxide anion ($O_2{^-}$), on membrane excitability in the rat MDH neurons. For this, we used patch clamp recording and confocal imaging. An application of X/XO ($300{\mu}M/30mU$) induced membrane depolarization and inward currents. When slices were pretreated with ROS scavengers, such as phenyl N-tert-butylnitrone (PBN), superoxide dismutase (SOD), and catalase, X/XO-induced responses decreased. Fluorescence intensity in the DCF-DA and DHE-loaded MDH cells increased on the application of X/XO. An anion channel blocker, 4,4-diisothiocyanatostilbene-2,2-disulfonic acid (DIDS), significantly decreased X/XO-induced depolarization. X/XO elicited an inward current associated with a linear current-voltage relationship that reversed near -40 mV. X/XO-induced depolarization reduced in the presence of $La^{3+}$, a nonselective cation channel (NSCC) blocker, and by lowering the external sodium concentration, indicating that membrane depolarization and inward current are induced by influx of $Na^+$ ions. In conclusion, X/XO-induced ROS modulate the membrane excitability of MDH neurons, which was related to the activation of NSCC.

• 방사성폐기물학회지
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• 제3권1호
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• pp.41-47
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• 2005

Cs$^{+}$ 이온에 대해 선택성을 갖는 ferrocyanide-음이온 교환수지를 제조하여 모의 제 염폐액 내에 존재하는 Cs$^{+}$ 이온에 대한 흡착실험을 수행하였다. 제조된 이온교환 수지가 citric acid를 주제염제로 하는 제염폐액 내에 존재하는 Cs+ 이온에 대한 흡착능력은 상용 양이온교환수지에 비해 4배 이상 효과적인 것으로 나타났다. 모의 제염폐액과 선택성 이온교환수지를 접촉시킨 후 360분이 경과하면 금속이온에 대한 흡착반웅이 평형에 도달하였다. 본 연구범위에서 Co$^{2+}$ 이온농도가 필요이상 증가하게 되면 Cs$^{+}$ 이온의 흡착율은 감소하였다. 과산화수소와 히드라진을 사용한 선택성 폐 이온교환수지의 재생실험 결과 전기중성화조건을 만족시키기 위해 Cs$^{+}$ 이온이 수지로부터 용출됨을 확인하였고 열화없이 재 사용가능성을 확인하였다.

• 한국환경과학회지
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• 제23권5호
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• pp.963-972
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• 2014

In this study, ibuprofen(IBP) degradation by the photochemical ($UV/S_2O{_8}^{2-}$) and sonochemical ($US/S_2O{_8}^{2-}$) processes was examined under various parameters, such as UV ($10{\sim}40{\pm}5W/L$) and US ($50{\sim}90{\pm}5W/L$) power density, optimum dosage of persulfate ion ($S_2O{_8}^{2-}$), temperature ($20{\sim}60^{\circ}C$) and anions effect ($Cl^-$, $HCO_3{^-}$, $CO{_3}^{2-}$). The pseudo-first-order degradation rate constants were in the order of $10^{-1}$ to $10^{-5}min^{-1}$ depending on each processes. The synergistic effect of IBP degradation in $UV/S_2O{_8}^{2-}$ and $US/S_2O{_8}^{2-}$ processes could investigated, due to the generation of $SO_4{^-}$ radical. This result can confirm from the produced $H_2O_2$ and $SO{_4}^{2-}$ concentration in each processes. IBP degradation rate affected by the $S_2O{_8}^{2-}$ dosage, temperature, power and anion existence parameters. In particular, IBP degradation rate increased with the increase of the temperature ($60^{\circ}C$) and applied power density (UV:$40{\pm}5W/L$, US:$90{\pm}5W/L$). On the other hand, anions effect on the IBP degradation was negative, due to the anion play as a the scavenger of radical.

• 분석과학
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• 제7권3호
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• pp.387-393
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• 1994

원자 흡수 분광법과 용매추출을 이용한 크롬의 정량분석 조건을 연구하였다. tertiary amine류 중 octy기를 갖는 trioctylamine(TOA)과 quaternary ammonium salt류 중 octyl기를 갖는 trioctylmethylammonium chloride(TOMAC)가 음이온 교환기로 사용되었다. 또한 첨가되는 산의 종류와 산의 농도 변화에 따라서 원자 흡수 분광기를 이용하여 흡광도를 측정하였다. TOA 사용시 염산의 농도가 0.1M에서 0.3M 사이, TOMAC 사용시 염산의 농도가 0.03M~0.1M 사이에서 최대 흡광도를 나타내었다. 산이 첨가된 MIBK에 용해된 TOA나 TOMAC와 Cr과의 mole 농도 비율이 1:1 이상이 된 것이 최대 추출 효율을 보였다. 추출과정을 검토한 결과, 본 실험에서 사용된 방법은 비슷한 다른 방법들과 비교하여 보면 크롬이 추출 효율이 좋은 것으로 판명되었다.