• 대한기계학회논문집B
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• 제21권2호
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• pp.264-274
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• 1997

A numerical analysis on condensation and coagulation of the metallic species with fly ash particles pre-existing in an incinerator was performed. Waste was simplified as a mixture of methane, chlorine, and small amounts of Pb and Sn. Vapor-phase amounts of Pb- and Sn -compounds were first calculated assuming a thermodynamic equilibrium state. Then theories on vapor-to-particle conversion, vapor condensation onto the fly ash particles, and particle-particle interaction were examined and incorporated into equations of aerosol dynamics and vapor continuity. It was assumed that the particles followed a log-normal size distribution and thus a moment model was developed in order to predict the particle concentration and the particle size distribution simultaneously. Distributions of metallic vapor concentration (or vapor pressure) were also obtained. Temperature drop rate of combustion gas, fly ash concentration and its size were selected as parameters influencing the discharged amount of metallic species. In general, the coagulation between the newly formed metal particles and the fly ash particles was much greater than that between the metal particles themselves or between the fly ash particles themselves. It was also found that the amount of metallic species discharged into the atmosphere was increased due to coagulation. While most of PbO vapors produced from the combustion were eliminated due to combined effect of condensation and coagulation, the highly volatile species, PbCl$_{2}$ and SnCl$_{4}$ vapors tended to discharge into the atmosphere without experiencing either the condensation or the coagulation. For Sn vapors the tendency was between that of PbO vapors and that of PbCl$_{2}$ or SnCl$_{4}$. To restrain the discharged amount of hazardous metallic species, the coagulation should be restrained, the number concentration and the size of pre-existing fly ash particles should be increased, and the temperature drop rate of combustion gas should be kept low.

• 한국세라믹학회지
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• 제29권9호
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• pp.711-718
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• 1992

Pb(Fe1/2Nb1/2)O3 was prepared by the molten salt synthesis method using an equimolar mixture of NaCl-KCl. Initial particle size could be controlled by varying the weight ratio of the NaCl-KCl to raw materials from 0.1 to 1.0, and the initial particle size effects on the sintering and dielectric properties of Pb(Fe1/2Nb1/2)O3 were investigated at the sintering temperature range from 90$0^{\circ}C$ to 105$0^{\circ}C$. As the weight ratio of salt increased, the average particle size decreased and the particle size distributions tended to narrow. As the initial particle size decreased, the linear shrinkage and density increased due to the promotion of densification. Dielectric constant increased with decreasing the initial particle size resulting from the increase of density and grain size.

• 대한화학회지
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• 제31권2호
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• pp.162-167
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• 1987

Monohydrogen arsenate를 전위차법으로 직접 정량하기 위하여 네가지 성분인 $Ag_2S$-PbS-$PbHAsO_4-Cu_2S$와 세가지 성분인 $Ag_2S$-PbS-$PbHAsO_4$로 된 전극이 제조되어 평가되었다. $Ag_2S$:PbS:$PbHAsO_4:Cu_2S$의 성분비(몰비)가 2.0:0.5:1.0:0.25인 전극이 전위차 감응, 안정도, 감응 속도와 재현성이 우수하였다. 0.1F $NH_4A_C-NH_4OH$ 완중용액 중의 일정한 이온 강도와 pH 8.50으로 조정된 $10^{-1}$~$10^{-4}M\;HA_SO_4^{2-}$ 농도 범위에서 실험하였고, $CN^-,\;I^-,\;S^{-2}$ 와 $Cl^-$등이 방해하였다.

• 분석과학
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• 제10권4호
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• pp.291-299
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• 1997

톱밥의 주성분인 cellulose를 이용하여 cellulose-OH를 cellulose-Cl로 전환시킨 다음 킬레이트 시약인 2,2'-iminodibenzoic acid염을 반응시켜 킬레이트 흡착제인 2,2'-iminodibenzoic acid-cellulose를 합성하였다. 그리고 합성된 흡착제를 이용하여 Pb(II)와 Cu(II)의 흡착성을 연구하였다. 흡착 특성에 대한 실험 결과, pH가 증가할수록 금속 이온의 흡착량이 증가함을 알 수 있었다. 최적 흡착 반응시간은 약 1시간, 흡착능과 회수량은 Cu(II)보다 Pb(II)의 경우가 더 좋음을 알 수 있었다.

• 한국결정성장학회지
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• 제15권3호
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• pp.99-103
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• 2005

NaCl-KCl을 flux로 사용한 용융염 합성법을 이용하여 $Pb(Sc_{1/2}Ta_{1/2})O_3$, 분말을 제조하였다. $700^{\circ}C$에서 $800^{\circ}C$의 온도범위에서 상형성 및 분말 상태의 변화를 조사하였다. 용융염 합성법으로 $750^{\circ}C$ 2시간 하소하였을 때, 순수한 페로브스카이트 구조를 가진 $Pb(Sc_{1/2}Ta_{1/2})O_3$ 상이 형성되었으며, 평균 입자 크기는 $0.5\{mu}m$ 이하이고 입방체와 유사한 형상을 갖는 분말이 제조되었다. DIA, X-선 회절 분석, 미세구조 변화를 통해 합성된 분말의 특성을 고찰하였다.

• 환경생물
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• 제30권2호
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• pp.128-135
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• 2012

본 연구는 말똥성게(Hemicentrotus pulcherrimus)의 생식세포 및 pluteus 유생을 이용하여 중금속인 납(lead, Pb)과 아연(zinc, Zn)의 독성을 조사였다. H. pulcherrimus 배우자 및 배아에 미치는 Pb과 Zn의 독성은 각각 31, 63, 125, 250, 500 ppb 및 16, 31, 63, 125, 250 ppb의 농도에서 조사하였다. 0.5 M KCl 용액을 이용하여 방란 및 방정을 유도하였고, 수정률 및 정상 배아발생률의 조사는 수정 후 각각 10분 및 64시간째 관찰하여 시행하였다. Pb 노출 시 수정률은 대조군과 비교하여 유의적인 변화가 없었다. 그러나 정상 배아발생률은 농도가 높을수록 농도의존적으로 유의적인 감소를 보였다. Zn을 노출시켰을 경우 수정률과 정상 배아발생률은 농도가 높을수록 농도의존적인 유의적 감소를 나타냈다. H. pulcherrimus의 정상 배아 발생에 대한 독성치는 각각 Pb (반수 영향농도 ($EC_{50}$) 45.13 ppb, 95% Cl 40.12~50.05 ppb), Zn (반수영향농도 ($EC_{50}$) 19.82 ppb, 95% Cl 18.26~21.31 ppb)로 나타났다. 또한 Pb과 Zn의 무영향농도(NOEC)는 각각 <31.25 ppb 및 <15.63 ppb로 나타났고, 최소영향농도(LOEC)는 31.25 및 15.63 ppb로 나타났다. 본 연구 결과, H. pulcherrimus의 초기 배아발생 과정은 Pb과 Zn 등의 중금속에 높은 민감성을 보인다. 따라서 H. pulcherrimus는 해양생태계 위해 평가를 위한 시험생물로서 사용이 가능하다고 사료된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.93-96
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• 2002

원자층증착법으로 제조한 청색 CaS:Pb 박막 형광체에 대한 열처리 및 전자빔 조사 효과찰 연구하였다. CaS:Pb 형광 박박의 열처리는 500 - $700^{\circ}C$ 온도범위에서 급속 열처리 공정으로 수행하였고, 1 kV, $20{\mu}A/cm^{2}$ 조건의 전자빔을 연속적으로 조사하여 열화를 가속시킨 후 처리 전, 후의 재료 및 cathololuminescence (CL) 특성을 비교 분석하였다. 원자층증착법으로 성장한 CaS:Pb 박막은 화학적 조성과 결정성이 우수하여 후속 열처리에 의해 발광특성이 크게 증가하는 경향을 보이지 않았으며, 전자빔에 의한 열화 정도는 판매되고 있는 형광체에 비하여 오히려 적었다. CL 강도가 초기값의 50%로 감소할 때까지 전자빔을 조사한 후에도 주목할만한 결정성 및 조성의 변화는 관찰되지 않았으나 전자빔 조사에 의해 표변에 두께 10 nm 내외의 탄소오염층이 형성됨을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제22권7호
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• pp.703-708
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• 2001

K2NiF4-type organic-based perovskites of the (C4H9NH3)2FexPb1-xCl4 (x=0.00, 0.25, 0.50, and 0.75) system have been synthesized using a low-temperatu re solution method under a flowing argon gas. When stoichiometric butylamine, iron chloride, and lead chloride are mixed, a yellow solution are obtained from slow cooling of 90 to -10 $^{\circ}C.$ The final product is a plate-like yellow crystal. The X-ray crystallographic analysis has been carried out using XRD in the range of $5^{\circ}{\leq}$ 2${\theta}$ ${\leq}80^{\circ}.$ The local symmetry around the absorbing Pb atom of the samples has been determined by the EXAFS spectroscopic study. The crystals assign to orthorhombic system by the XRD analysis. The FT-IR spectra are analyzed in the range of 600 to 3300 cm-1 . DSC and TGA are measured to detect thermal stability between 30 and 300 $^{\circ}C.$ Two endothermic peaks are detected in all samples. The electrical conductivity has been measured using the four-probes technique for the (C4H9NH3)2FexPb1-xCl4 system in 300-460 K. Photoluminescence phenomenon was also investigated at room-temperature.

• 한국지하수토양환경학회지:지하수토양환경
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• 제23권1호
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• pp.74-84
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• 2018

Pot experiments were conducted to assess the applicability of ferric chloride ($FeCl_3$) as a washing agent for laboratory scale in-situ soil washing of paddy soil contaminated with Pb. During the monitoring period for nearly 90 days, the concentrations of Fe and Mn in the soil solution were lower than that of control soil due to lime ($Ca(OH)_2$) amendment for pH recovery. Lime amendment also affected solubility and fractionation of Pb into soil matrix. The result showed that Pb concentrations of soil solution were consistently lower than that of control soil, and the concentration in the exchangeable fraction in washed soil decreased from 13 to 2 mg/kg. There was no significant difference of biomass yield of rice plant in each pots, and Pb contents in rice roots and grains in washed soil decreased to 50 and 78%, respectively, of the control soil. Therefore, $FeCl_3$ could be used as an acceptable in-situ washing agent for agricultural paddy soil if appropriate soil pH management is subsequently practiced.

• 한국세라믹학회지
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• 제23권6호
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• pp.33-36
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• 1986

The $PbTiO_3$is well known materials having remarkable ferroelectric piezoelectric and pyro-electric properties. Thin films of the lead titanite has been successfully fabricated by Chemical Vapor Deposition on the borosilicate glass and titanium substrate. The $PbTiO_3$ thin film deposited on the borosilicate glass using the $PbCl_2$, $TiCl_4$ dry oxygen and wet oxygen at different temperatures (50$0^{\circ}C$-$700^{\circ}C$) grows along the (001) preferred orientation. On the other hand the $PbTiO_3$ thin film deposited on the titanium substrate using the PbO grows along the (101) preferred orientation. Growth orientation of deposited $PbTiO_3$ depends on the reaction species irrespective of substrate materials. Maximum dielectic constant and loss tangent of the $PbTiO_3$ thin film deposited on the titanium substrate are about 90 and 0.02 respectively, . Deposition rates of $PbTiO_3$ deposited on the borosilicate glass and titanium substrate are 10-15 ${\mu}{\textrm}{m}$/hr. Titanium dioxide interlayer formed be-tween $PbTiO_3$ film and titanium substrate material, It improved the adhesion of the film.