• Journal of the Korean Chemical Society
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• v.51 no.6
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• pp.560-568
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• 2007

The aim of this study is to investigate the terminology of chemically unclear ‘heavy metals' which were expressed in the Korean secondary science textbook in terms of the definition, the type and the meaning. Initial results showed that six of ‘Chemistry I' textbooks among these texts defined a heavy metal with the density and described it as a metal which is hazardous and continuously accumulated in the human body. Specifically, cadmium, lead and mercury were presented as examples of the hazardous metal in all of the eight textbooks but non-metals such as arsenic and absolutely essential metals including chrome, manganese, iron, cobalt, nickel and copper were also given in the texts. Most of the texts described the hazardousness and toxicity of the metal too simple to understand the mechanism of its intoxication despite considering all of the factors including its oxidation state, residual amount and reactivity with biomolecules of the human body. Such an ambiguous definition and explanation may excluded in the textbook because the chemically undefined chemical vocabulary leads students to cause an alternative conception of the heavy metal, which means that the metal could be identical with toxins.

• Resources Recycling
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• v.21 no.6
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• pp.45-50
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• 2012

The room-temperature electrodeposition of metallic lithium was investigated from ionic liquid, 1-methyl-1-propylpiperidinium bis(trifluoromethanesulfonyl)imide (PP13TFSI) with lithium bis (trifluoromethanesulfonyl)imide (LiTFSI) as a lithium source. Cyclic voltammograms on gold working electrode showed the possibility of the electrodeposition of metallic lithium, and the reduction current on a gold electrode was higher than the value on platinum and copper. The metallic lithium could be electrodeposited on the gold electrode under potentiostatic condition at -2.4 V (vs. Pt-QRE) and was confirmed by analytical techniques including XRD and SEM-EDS. The dendrite-typed electrodeposits were composed of a metallic lithium and a alloy with gold substrate. And any impurity could be detected except for trace oxygen introduced during handling for the analyses.

• Korean Journal of Environmental Agriculture
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• v.27 no.4
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• pp.328-336
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• 2008

Metal mining district drainage is a well recognized source of environmental contamination. Oxidation of metal sulfides produces acidic and metal-rich waters that contaminate local surface water and ground water in mines, mine dumps, and tailing impoundments. This monitoring study was carried out to investigate the stream water quality and pollution as affected by the Sambo mine drainage in relation to the relative distance from the mine. It obvious that pH values of the mine drainage ranged from 5.8 to 6.9, while the average concentrations of the dissolved chemical constituents for EC, $SO_4^{2-}$, $K^+$, $Ca^{2+}$, and $Mg^{2+}$ were $1.77\;dS\;m^{-1}$, 929, 14.6, 263.3, and 46.9 mg/L in mine drainage discharged from the main waste rock dumps (WRD), respectively. Furthermore, EC values and sulfate concentrations exceeded the critical toxicity levels in agricultural water for rice plant ($1.0\;dS\;m^{-1}$ for EC and 54.0 mg/L for $SO_4^{2-}$). Also, the average of dissolved cadmium concentrations ($0.016{\sim}0.021\;mg/L$) was higher than water quality standard (0.01 mg/L) for agricultural water in Korea, in addition to Zn, Fe and Mn were higher than trace metals maximum concentrations which recommended by FAO for irrigation water. The results indicate that mine drainage discharged from the Sambo mine affected stream water at least to distance of 1 km downstream of the mine water discharge point. EC values, $SO_4^{2-}$ and $Ca^{2+}$ concentrations in discharged water positively correlated with dissolved Cd, Zn, Al and Mn concentrations, while the pH values negatively correlated. In addition, EC values, $SO_4^{2-}$ and $Ca^{2+}$ concentrations were negatively correlated with pH values.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.279-279
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• 2013

차세대 태양전지로 주목받는 화합물 박막 태양전지(CIGS, CdTe, etc)는 광흡수계수가 매우 높아 얇은 두께의 광흡수층으로도 빛을 효과적으로 흡수할 수 있으므로 광흡수층의 역할이 매우 중요하며 이에 대한 정확한 정보와 이해는 필수적이다. 특히 GIGS 박막 태양전지의 정량 및 각 원소의 깊이 방향의 분포를 분석하는 것은 박막형 태양전지 개발에 크게 기여한다 [1,2]. 본 실험에서는 조성비를 알고 있는 균질한 CIGS박막을 표준시료로 사용하여 ICP-MS로 측정하여 평균농도를 구한 뒤 TOF-SIMS, D-SIMS, Auger Electron Spectroscopy (AES) 로 깊이 방향 분석 결과를 통해 상대감도(RSF)를 계산한 후 각 원소의 농도로 변환하여 정량분석 결과를 얻었다. 일반적으로 손쉽게 정량적인 정보를 얻는 AES에 비해 정량성이 떨어지는 TOF-SIMS와 D-SIMS는 스퍼터링시 사용되는 Cs 빔과 시료 내 금속과의 클러스터 이온(GaCs+와 InCs+)의 깊이 방향 조성을 이용하면 매트릭스 효과를 배제할 수 있어서 좀 더 정확한 정량 분석이 가능하므로 시료내 금속과 Cs 이 결합된 클러스터 이온의 깊이 방향 조성을 측정하여 각원소의 농도를 계산하였고 스퍼터링 에너지를 포함한 실험 변수에 따른 재현성 및 정량성의 차이를 비교분석하였다. 또한 CIGS층에 불순물로 들어 있는 미량원소들의 깊이 분포도도 함께 관찰하였다.

• 한국지구과학회:학술대회논문집
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• 2006.02a
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• pp.111-115
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• 2006

최근 경기도 가평지역에서 새로운 철운석이 발견되었으며, 이는 한반도에 낙하(fall) 또는 발견(find)된 운석 중 다섯 번째 기록이다. 가평운석(가칭)은 북위 $37^{\circ}52'08'$, 동경$127^{\circ}27'54'$, 고도 147m 지점에서 발견되었으며, 운석의 분류상 철운석에 속한다. 가평운석의 표면은 지표상에서 풍화를 받은 흔적이 나타나나, 내부는 비드만스태튼 무늬(Widmanstatten pattern)와 같은 철운석의 특징이 잘 보존되어 있다. 가평운석의 암석학적, 광물학적 기재와 분류를 위해 주사전자현미경(Scanning Electron Microscope) 및 전자 현미분석기(electron probe micro-analyzer)를 이용했다. 풍화의 산물인 철산화물이 나타나는 최외각부를 제외하면 가평 운석은 거의 순수한 철-니켈 금속광물(Fe-Ni metal)로 이루어져 있다. 이 중 니켈 함량이 적은 카마사이트(kamacite)가 대부분이며 소량의 태나이트(taenite)가 산출되어 비드만스태튼 무늬를 구성한다. 비드만스태튼 무늬의 특징에 의한 분류에 따르면 가평운석은 중립질 또는 조립질 옥타헤드라이트(octahedrite)에 속한다. 철운석은 화학적으로 열 개 이상의 하부그룹으로 세분되며, 가평운석의 정확한 하부그룹으로의 분류는 친철원소에 대한 미량분석이 추가적으로 필요하다. 가평운석의 냉각률은 $^{\sim}1^{\circ}C/Ma$이하로 나타나며, 이는 가평운석이 천천히 냉각된 비교적 규모가 큰 소행성의 핵에서 유래했음을 지시한다.

• Economic and Environmental Geology
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• v.45 no.3
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• pp.217-235
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• 2012

We evaluated the geochemical characteristics and their potential pollution of Asian Dusts in Daejeon, Korea during spring 2007. Compared with the chemical compositions of soils in source area of Asian Dust, those of aerosols in Daejeon were enriched with trace elements (ten to hundred fold), inferring that pollutants from China have affected on local environment in adjoining country such as Korea. Chemical analysis of aerosols during Asian dust showed that fine particles ($PM_{2.5}$) contained high contents of trace elements such as Cr, Cu, Pb, Zn, V, S, As, Cd, Co, Ni, Mo, Sb, Cs, Rb, Th, Sc and Y. In the case of TSP (Total Suspended Particle), Zr, Sr, Ba, Li, Th and U were contained much more than other trace elements. The contents of some elements (i.e. Li, Cs, Co, U, Cr, Ni, Rb, V, Th, Y, Sr and Sc) in aerosols collected in Asian Dust period, which are not likely enriched by air pollutants, were higher (2 - 4.2 fold) than those in Non Asian Dust period, indicating that these elements could be used as indicator elements for determining the occurrence of Asian Dust phenomena (especially, Sr, V, Cr & Li). In the case of Asian Dust coming through the big cities and/or industrial areas of China, the domestic aerosols had higher contents of trace elements (such as S, Cd, Zn, Pb, Cu, Mo and As) than those from Northeastern China via North Korea, indicating that the transportation courses of air mass are very important to determine the pollution degrees. Using the enrichment factors of trace elements in aerosols during Asian Dust and Non Asian Dust, we identified that some elements (i.e. S, Zn, Cu, Pb, As, Mo and Cd) were most problematic in terms of environmental hazard aspects, and these elements could affect adverse effects on human health as well as ecosystem and surface environment (soil and water) through long-lived precipitation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.1
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• pp.35-41
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• 2006

Antibacterial activities of the trace elements in combination with the food additives were measured against 6 kinds of food-borne microorganisms such as Escherichia coli, Vibrio parahaemolyticus, Staphylococcus aureus, Bacillus cereus, Bacillus subtilis and Pseudomonas fluorescens. The difference of antibacterial activity was not shown among the kinds of food additives, such as dextrin, gelatin and collagen. Zn and Ge in combination with food additives had strong antibacterial effect. Especially, $1\%$ zinc acetate in combination with $1\%$ gelatin was more effective against P. fluorescens and S. aureus than against Bacillus sp., E. coli and V. parahaemolyticus. Minimum inhibitory concentration of zinc acetate in combination with $1\%$ gelatin appeared to be 0.5 mg/mL on S. aureus and P. fluorescens, and 1.0 mg/mL on E. coli, V. parahaemolyticus, B. cereus and B. subtilis. Minimum bactericidal concentration of zinc acetate in combination with $1\%$ gelatin appeared to be 0.5 mg/mL on P. fluorescens and 1.0 mg/mL on E. coli, V. parahaemolyticus, S. aureus, B. cereus and B. subtilis. The zinc acetate in combination with gelatin showed stronger inhibitory effect in acidic range below pH 6.0, and remained active even after heat treatment at $121^{\circ}C$ for 15 min. In comparison with control, the viable cell counts of fish pastes, which were coated with the solution containing both $1\%$ zinc acetate and $3\%$ gelatin, were decreased by more than 100-fold until the storage of 7 days at $10^{\circ}C$. The results indicate that the combined use of zinc acetate and some food additives could prolong the shelf life of fish pastes by 8 days or more at $10^{\circ}C$.

• Analytical Science and Technology
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• v.9 no.4
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• pp.364-372
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• 1996

The sorption and desorption properties of U(VI), Th(IV), Zr(IV), Cu(II), Pb(II), Ni(II), Zn(II), Cd(II) and Mn(II) ions on XAD-16-[2-(2-thiazolylazo)-p-cresol](TAC) chelating resin were studied by elution method for selective separation, concentration and recovery of trace metal ions in sea water. The optimum conditions for the sorption of metal ions were examined with respect to flow rate, pH and concentration of buffer solution. The overall capacities of some metal ions on this chelating resin were 0.41mmol U(VI)/g resin, 0.55mmol Th(IV)/g resin, 0.43mmol Cu(II)/g resin, and 0.32mmol Zr(IV)/g resin, respectively. The elution order of metal ions obtained from breakthrough capacity and overall capacity at pH 5.0 was found as Th(IV)>Cu(II)>U(VI)>Zr(IV)>Pb(II)>Ni(II)>Zn(II)>Cd(II)>Mn(II). Desorption of characteristics for metal ions were investigated with desorption agents such as $HNO_3$, HCl, $HClO_4$, $H_2SO_4$, and $Na_2CO_3$. It was found that most of metal ions except Zr(IV) showed high desorption efficiency with 2M $HNO_3$. But, desorption and recovery of Zr(IV) ion were successfully performed with 1M $H_2SO_4$. The resin was applied for separation and preconcentration of trace amount of U(VI) ion from artificial sea water and the recovery of U(IV) was over 96%.

• Journal of Korea Soil Environment Society
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• v.4 no.1
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• pp.97-108
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• 1999

Reduction 2, 4, 6-trinitrotoluene by zero valent iron was studied in a batch reactor under anoxic conditions. Results showed that the removal of trinitrotoluene (TNT)followed a pseudo-first order reaction and the rate was linearly dependent on the available reactive surfau area of the zero valent iron surface area, resulting a rate constant of 0.0981min$^{1}m$$^{-2}m$. High concentrations of the final product, presumably triaminotoluene which needs to be treated by other means, accumulated in the solution. However , little amount of TAT was extracted from the metal surface by using acetonitrile or phosphate buffered water (pH 7.0). Other common major intermediate in biological TNT degradation, a group of aminodinitrotoluenes, was not detected in the solution. Therefore, it is postulated that the reduction of nitro group by $Fe^0$ occurs simultaneously in all three positions and a TNT reduction model by zero valent iron was suggested.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.392-392
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• 2008

나노크기의 반도체 물질은 표면적/부피 비와 그 크기에 의해 광학적, 전기적 특성이 크게 영향을 받는다. 나노크기의 반도체 재료 중 ZnO는 3.37eV의 넓은 에너지 밴드갭을 가지고 있으며, 60meV의 큰 엑시톤(exciton) 결합에너지의 특성을 가지고 있어 UV 영역의 소스로서 가장 활용도가 클것으로 예상된다. 1 차원 ZnO 나노구조는 청색과 자외선 발광소자 및 광전자 소자, 화학적 센서로 활용이 가능하다. whisker, nanowires, norods, nanonail, nanoring 등과 같은 ZnO 나노구조의 형태와 크기는 합성장비와 공정조건에 크게 영향을 받고 서로 다른 광 특성 결과를 나타낸다. ZnO 나노구조의 합성을 위해 다양한 금속 촉매를 이용한 기상-액상-고상(VLS)의 성장 메카니즘이 연구되었다. 그러나 이 방법은 촉매로 사용된 금속이 불순물로 작용하는 결점을 가지고 있다. 최근에는 기판위에 아무런 촉매도 사용하지 않은 ZnO 의 합성에 대해 많은 연구가 진행되고 있다. 그러나 촉매없이 합성된 나노구조의 형태와 성장방향은 초기단계에서 불규칙한 원자배열로 인해 합성상태의 제어 (방향, 형상 등)가 매우 어렵다. MOCVD 장비 금속 촉매를 이용하지 않고도 미량의 Zn 와 $O_2$ 량을 일정하게 조절함으로써 형상 및 방향성을 제어 할 수 있다는 장점을 가지고 있다. 또한 본 연구에 사용된 MOCVD 장비의 경우 추가적인 케리어 가스 유입을 통해 나노막대의 aspect ratio 조절이 가능하다. 본 연구는 MOCVD 장비를 이용해 촉매를 사용하지 않고 1 차원 ZnO 나노막대를 합성하였고, 추가적 케리어 가스 유량을 변화시킴으로써 형태 변화 및 발광특성에 관한 영향을 연구하였다.