• 자원리싸이클링
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• 제21권6호
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• pp.74-81
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• 2012

온도에 따른 Pourbaix Diagram 을 열역학 계산에 의해 구성하여 수용액 상 은의 회수반응에 미치는 온도의 영향을 파악하였다. 온도의 상승에 따라 물의 안정성은 pH 변화에 대해 더 크게 영향을 받으며 ${Ag^+}_{(aq)}$의 안정영역은 감소하는 것으로 나타났다. 온도가 하강함에 따라 $Ag_{(aq)}$를 $Ag_{(s)}$ 및 $Ag_2O_{3(s)}$ 형태로 회수하고 온도 상승 시에는 $Ag_{(aq)}$를 $Ag_2O_{(s)}$ 및 $Ag_2O_{2(s)}$의 형태로 회수하는 것이 화학반응상 보다 유리할 것으로 고찰되었다. $pH{\leq}2$ 이하의 강산성 영역에서는 온도 상승에 따른 은 회수 효율성이 감소하고 pH가 2 이상인 조건에서는 온도 증가에 따라 은의 회수 효율성이 증대될 것으로 파악되었다. 또한, 은을 원소 상태로 회수하는 방안은 산화은 형태로 회수하는 방안에 비해 온도변화에 대해 더욱 민감하게 영향을 받는 것으로 고려되었다.

• 분석과학
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• 제12권2호
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• pp.171-175
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• 1999

Carbon paste electrodes, modified with podands containing more than two sulfur atoms, have been employed for the voltammetric determination of Ag(I) ion from aqueous solution. The voltammetric response was characterized with respect to paste composition, preconcentration method, kind of anion, variation of pH, Ag(I) ion concentration, and possible interferences. Linear calibration curves were obtained for Ag(I) ion concentration ranging from $1.0{\times}10^{-6}$ to $9.0{\times}10^{-5}M$, and detection limit was $5.0{\times}10^{-7}M$.

• 분석과학
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• 제15권1호
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• pp.91-95
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• 2002

Carbon paste electrodes, modified with 5,6,14,15-dibenzo-1,4-dioxa-8,12-diazacyclopentadeca-5,14-diene containing different ligating atoms of oxygen and nitrogen, have been employed for the voltammetric determination of Ag(I) ion from aqueous solution. The voltammetric response was characterized with respect to paste composition, preconcentration method, kind of anion, variation of pH, Ag(I) ion concentration, and possible interferences. Linear calibration curves were obtained for Ag(I) ion concentration ranging from $3.0{\times}10^{-6}M$ to $8.0{\times}10^{-5}M$, and detection limit was $8.5{\times}10^{-7}M$.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2309-2314
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• 2012

Ag deposited N-$TiO_2$ composite nanoparticles were prepared via $NH_3$ plasma treatment. X-ray diffraction, UV-vis spectroscopy, photoluminescence, and X-ray photoelectron spectroscopy were used to characterize the prepared $TiO_2$ samples. The plasma treatment did not change the phase composition and particle sizes of $TiO_2$ samples, but extended its absorption edges to the visible light region. The photocatalytic activities were tested in the degradation of an aqueous solution of a reactive dyestuff, methylene blue, under visible light. The photocatalytic activities of Ag deposited N-$TiO_2$ composite nanoparticles were much higher than Ag-$TiO_2$, N-$TiO_2$, and P25. A possible mechanism for the photocatalysis was proposed.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권4호
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• pp.309-314
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• 2005

We performed a basic experiment for the rapid, on-line, real-time measurement of hepatitis B surface antigen using a surface plasmon resonance biosensor. We immobilized anti­HBsAg (hepatitis B surface antigen) polyclonal antibody, as a ligand, to the dextran layer on a CM5 chip surface that had previously been activated by N-hydroxysuccinimide. A sample solution containing HBsAg was fed through a microfluidic channel, and the reflecting angle change due to the mass increase from the binding was detected. The binding characteristics between HBsAg and its polyclonal antibody followed the typical monolayer adsorption isotherm. When the entire immobilized antibody had interacted, no additional, non-specific binding occurred, suggesting the immunoreaction was very specific. The bound antigen per unit mass of the antibody was independent of the immobilized ligand density. No significant steric hindrance was observed at an immobilization density of approximately $17.6 ng/mm^2$. The relationship between the HBsAg concentration in the sample solution and the antigen bound to the ligand was linear up to ca. $40{\mu}g$/mL. This linearity was much higher than that of the ELISA method. It appeared the anti­gen-antibody binding increased as the immobilized ligand density increased. In summary, this study showed the potential of this SPR biosensor-based method as a rapid, simple and multi­sample on-line assay. Once properly validated, it may serve as a more efficient method for HBsAg quantification for replacing the ELISA.

• Bulletin of the Korean Chemical Society
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• 제26권10호
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• pp.1529-1532
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• 2005

A simple and cost effective method for separation and preconcentration of Ag(I) at the $10^{-7}\;mol\;L^{-1}$ level in the environmental and mineral samples is present. The method is based on the flotation of Ag(I)-iodide complex as an ion-associate with ferroin in pH of 4 from a large volume of an aqueous solution (500 mL) using nheptane. The floated layer was then dissolved in dimethylsulfoxide (DMSO) for the subsequent spectrophotometric determination. Beer's law was obeyed over a range of 2.0 ${\times}$ $10^{-7}$-4.0 ${\times}$ $10^{-6}$ mol $L^{-1}$ with the apparent molar absorptivity of 2.67 ${\times}$ $10^5$ L $mol^{-1}\;cm^{-1}$. The detection limit (n = 5) was 4 ${\times}$ $10^{-8}$ mol $L^{-1}$, and RSD (n = 5) obtained for 2.0 ${\times}$ $10^{-6}$ mol $L^{-1}$ of Ag(I) was 2.2%. The interference effects of a number of elements was studied and found that only $Hg^{2+}$ at low concentration, and $Pb^{2+}$, $Cd^{2+}$, $Cu^{2+}$, and $Fe^{3+}$ ions at moderately high concentrations were interfered. To overcome on these interference effects, the solution was treated with EDTA at a buffering pH of 4 and passed through a column containing Amberlite IR-120 ionexchanger resin, just before the flotation process. The proposed method was applied to determine of Ag(I) in a synthetic waste water, a photographic washing sample and a geological sample and the results was compared with those obtained from the flame atomic absorption spectrometry. The results were satisfactorily comparable with together, so that the applicability of the proposed method was confirmed in encountering with the real samples.

• 대한금속재료학회지
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• 제50권12호
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• pp.931-937
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• 2012

The microstructure of Cu-15 wt%Ag composites fabricated by equal channel angular pressing (ECAP) with intermediate heat treatment at $320^{\circ}C$ was investigated by transmission electron microscopy (TEM) observations. Ag precipitates with a thickness of 20-40 nm were observed in the eutectic region of the Cu-15 wt%Ag composite solution treated at $700^{\circ}C$ before ECAP. The Cu matrix and Ag precipitates had a cube on cube orientation relationship. ECAPed composites exhibited ultrafine-grained microstructures with the shape and distribution dependent on the processing routes. For route A in which the sample was pressed without rotation between each pass, the Cu and Ag grains were elongated along the shear direction and many micro-twins were observed in elongated Cu grains as well as in Ag filaments. The steps were observed on coherent twin boundaries in Cu grains. For route Bc in which the sample was rotated by 90 degrees after each pass, a subgrain structure with misorientation of 2-4 degree by fragmentation of the large Cu grains were observed. For route C in which the sample was rotated by 180 degrees after each pass, the microstructure was similar to that of the route A sample. However, the thickness of the elongated grains along the shear direction was wider than that of the route A sample and the twin density was lower than the route A sample. It was found that more microtwins were formed in ECAPed Cu-15 wt%Ag than in the drawn sample. Grain boundaries were observed in relatively thick and long Ag filaments in Cu-15 wt%Ag ECAPed by route C, indicating the multi-crystalline nature of Ag filaments.

• 대한화학회지
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• 제47권4호
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• pp.315-324
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• 2003

유기용매인 클로로포름 매질에서 소수성의 합금 나노 미립자를 만드는 새로운 방법에 대해 연구하였다. 소수성 합금 나노 미립자들은 계면활성제(sodium bis(2-ethyl hexyl)-sulfosuccinate, NaAOT)를 포함한 클로로포름 용액에 금속염 즉, $HAuCl_4,\AgNO_3,\Cu(NO_3)_2$을 사용하여 합금의 조성을 조절하여 혼합한 후 sodium borohydride $(NaBH_4)$로 환원시켜 합성하였다. Au/Ag, Au/Cu 합금 나노 미립자의 조성은 1:3, 1:1, 3:1의 몰비로 변화시키면서 합성하였다. UV/Visible, TEM, XPS를 사용하여 합금 나노 미립자의 특성을 측정하였다. Au/Cu 합금 나노 미립자의 표면 공명 흡수는 순수한 금인 경우의 최대흡수 파장인 520 nm에서 순수한 구리의 표면 공명 흡수인 570 nm까지 선형적으로 변하였고, Au/Ag 합금 나노 미립자는 순수한 은의 최대흡수 파장인 405 nm에서 순수한 금의 경우인 520 nm까지 선형적으로 변하였다. 합금 나노 미립자의 Au4f, Ag3d, Cu2p 전자의 구속 에너지는 합금의 조성 비율에 따라 달라지게 된다. 합성된 합금 나노 미립자들은 매우 균일하고 장시간 안정한 분산상태를 유지하였다. 이러한 결과로부터 본 연구에서 사용한 방법은 소수성의 합금 나노 미립자를 합성하는데 매우 효과적인 방법이라고 사료된다.

• 약학회지
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• 제7권2_3호
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• pp.67-71
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• 1963

Studies the reaction mechanism and optimal reaction condition of the process of preparing sodium isocyanate, by means of heating of sodium carbonate and urea. Proposing, at the sametime, the quantitative analyzing method of sodium isocyanate in the presence of impurities of $Na_{2}CO_{3}$, urea and biuret. 1. Sodium isocyanate could be prepared by means of heating reaction of sodium carbonate and urea. 2. Adding urea into the heated sodium carbonate is reasonable. 3. Quantitative analysis of sodium isocyanate in the presence of impurities, $Na_{2}CO_{3}$, urea and biuret could be done by the following method:-adding nitrobarite solution into sample solution in order to remove $CO_{3}"$ and neutralize the solution, filtering off $BaCO_{3}$, and then precipitating isocyanate as a silver salt, filtering off AgNCO, and then, titrating remaining $AgNO_{3}$ with $NH_{4}SCN$, (indicator $FeNH_{4}(SO_{4})_{2})$/TEX>

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 춘계학술발표강연 및 논문개요집
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• pp.49-49
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• 2003

Nanometer sized zinc oxide (ZnO) powder was synthesized by a novel "solution-combustion method" and its photocatalytic activity was evaluated with the recovery of Ag from a used photofilm developing solution. Different parameters affecting the reaction rates like wavelength of the W light used, reaction temperature, mass of the used photocatalyst, and effect of scavenger were tested. The optimum parameters were found as follows. UV wavelength of less than 385nm, reaction temperature between 40- 60 $^{\circ}C$, photocatalyst concentration of 3-6 g/1, and scavenger concentration of 0.3-0.4 g/1.