• Title/Summary/Keyword: 수소 이온 반응 계수

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Sorption of Radioactive Cobalt and Ruthenium on Soil Minerals (방사성 코발트 및 루테늄의 토양 흡착)

  • Lee, Byung-Hun;Hands, J.D.
    • Journal of Radiation Protection and Research
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    • v.15 no.2
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    • pp.7-16
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    • 1990
  • The sorption of radioactive cobalt and ruthenium on alumina, silica gel, zeolite 3A, kaolin and Na-bentonite has been studied as a function of pH. nuclide concentration and ionic strength. Retardation factor for cobalt and ruthenium on soil minerals was determined through porosity measurement. Hydrolysed species, cobalt and ruthenium interact with solid surfaces by physical adsorption processes. Freundlich sorption isotherms for cobalt and ruthenium are effectively linear. The sorption decreases with increasing ionic strength for cobalt and ruthenium. The effect of increasing porosity on the retardation factor countered the effect of a significant increase in the distribution coefficient.

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Lithium Ion Selective Electrode Based on a Synthetic Neutural Carrier (중성운반체를 이용한 리튬이온 선택 전극)

  • Kim, Jae Sang
    • Analytical Science and Technology
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    • v.5 no.1
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    • pp.33-39
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    • 1992
  • THF-based crown-4 of 16-membered rings having tetrahydrofuran unit was synthesized by an acid-catalyzed condensation of furan and acetone followed by hydrogenation in an effort to obtain highly elective ionophores for lithium ions. The new ionophore was compared with previously reported ionophores under similar measurement conditions with the same plasticizer, tris(2-ethylhexyl) phosphate in poly(vinyl chloride)(PVC) membrane electrodes. Separate solution method was used to determine relative selectivity coefficients for the electrode. The selectivity coefficients($K_{LiM}^{POT}$) of lithium over ammonium, alkali and alkaline earth metal ions go from about $2.4{\times}10^{-1}$ to $2.3{\times}10^{-4}$ to working range and pH dependence have also been studied.

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Electrochemical Behavior of Dissolved Hydrogen and Hydrogen Peroxide in Boric Acid Solution at the Elevated Temperature (붕산수용액 매질에서 용존수소와 과산화수소의 고온 전기화학 거동연구)

  • Yeon Jei-Won;Woo Seung-Kyun;Choi Young-Ku;Jung Yongju;Kim Won-Ho
    • Journal of the Korean Electrochemical Society
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    • v.7 no.1
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    • pp.21-25
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    • 2004
  • The electrochemical behaviors of dissolved hydrogen and hydrogen peroxide at a platinum disk electrode were investigated in boric acid solution by potentiostatic polarization method at the temperature of 25 and $200^{\circ}C$. The oxidation of dissolved hydrogen at $25^{\circ}C$ was kinetically controlled reaction, the rate of which depends upon the electron transfer on the electrode surface. As temperature was raised, however, the electrochemical characteristics of dissolved hydrogen were changed from a kinetically controlled reaction to a diffusion controlled one. One notable feature, with dissolved hydrogen at high temperature, is that an abnormal potential range was observed, where the oxidation rate of dissolved hydrogen rapidly decreased just before starting potential of water oxidation. We think it is caused by the deactivation of the electrode that results from the adsorption of hydroxyl ion on the surface of the platinum disk. On the contrary, a definite change with temperature was not identified in the case of the hydrogen peroxide except for the increase in current density that was due to the increasing diffusion coefcient with an increase of temperature.

Selective determination of mercury (II) ion in aqueous solution by chemiluminescence method (화학발광법에 의한 수용액 중의 선택적 수은(II) 이온 정량)

  • Kim, Kyung-Min;Jang, Taek-Gyun;Kim, Young-Ho;Oh, Sang-Huyb;Lee, Sang-Hak
    • Analytical Science and Technology
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    • v.24 no.4
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    • pp.243-248
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    • 2011
  • A selective determination method of mercury (II) ion in aqueous solution by luminol-based chemiluminescence system (luminol CL system) has been developed. Determination of metal ions such as copper (II), iron (III), chromium (III) ion in solution by the luminol CL system using its catalytic role in the reaction of luminol and hydrogen peroxide has been reported by several groups. In this study, the catalytic activity of mercury (II) ion in the reaction of luminol and hydrogen peroxide was observed by the enhanced CL intensity of the luminol CL system. Based on this phenomenon, experimental conditions of the luminol CL system were investigated and optimized to determine mercury (II) ion in aqueous solution. While mercury (II) ion in mixed sample solution containing mercury (I) and (II) ions highly enhanced the CL intensity of the luminol CL system, the mercury (I) ion could not enhanced the CL intensity. Thus selective determination of the mercury (II) ions in a mixture containing mercury (I) and (II) ions could be achieved. Each concentration of mercury (I) and (II) ions in aqueous solution can be obtained from the results of the CL method that give the concentration of only mercury (II) ion and the inductively coupled plasma (ICP) method that give the total concentration of mercury ions. On the optimized conditions, the calibration curve of mercury (II) ion was linear over the range from $1.25{\times}10^{-5}$ to $2.50{\times}10^{-3}M$ with correlation coefficient of 0.991. The detection limit of mercury (II) ion in aqueous solution was calculated to be $1.25{\times}10^{-7}M$.

$^{14}C$를 함유한 톨루엔의 산화반응 및 액체섬광계수를 이용한 정량적 분석

  • 이흥래;안홍주;송병철;김정석;박순달;한선호;지광용
    • Proceedings of the Korean Radioactive Waste Society Conference
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    • 2004.06a
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    • pp.225-225
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    • 2004
  • 원전 1차 냉각계통내 화학첨가제인 amine 또는 과산화수소를 사용하면서 $^{14}N$(n, P)$^{14}C$$^{17}O$(n, $\alpha$)$^{14}C$의 핵반응으로 생성된 $^{14}C$는 냉각수내에서 방사성 폐기물로 존재하게 된다. 이들 방사성 폐기물은 pH에 따라 다르지만 수용액상에서는 대부분 $CO_2$, $H_2CO_3$, ${HCO_3}^-$${CO_3}^{2-}$로 존재하고, 나머지 약 20% 정도는 유기성 탄소로는 메탄이 존재하는 것으로 알려져 있다. 폐이온 교환수지 내에 존재하는 $^{14}C$는 시간이 경과함에 따라서 방향족 화합물로 이온교환이 발생할 수가 있다.(중략)

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r.f.PACVD를 이용한 Si이 첨가된 DLC 필름의 미세구조 및 기계적 특성 평가

  • 박세준;조성진;이광렬;고대홍
    • Proceedings of the Korean Vacuum Society Conference
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    • 1999.07a
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    • pp.137-137
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    • 1999
  • DLC(diamond-like carbon) 필름은 경도가 높고 마찰계수가 낮다는 장점을 가지고 있기 때문에 내마모성 코팅이나 윤활성 코팅에 대한 많은 응용이 이루어지고 있다. 그러나 DLC 필름은 수 GPa 정도의 높은 필름 자체의 큰 잔류 응력을 가지며, 마찰 계수가 주변환경에 매우 큰 영향을 받는다는 단점이 있다. 이러한 단점은 DLC 필름의 응용에 대한 저해 요인이 되며, 이 점을 보완하기 위하여 DLC 필름에 Si를 첨가한 연구들이 진행되고 있다. 본 실험에서는 r.f-PACVD 법을 이용하여 Si이 첨가된 DLC 필름의 바이어스 전압에 따른 특성변화를 연구하였다. 사용한 반응 가스는 벤젠(C6H6)과 희석된 (SiH4:H2=10:90)이며, 희석된 실랜과 벤젠의 첨가비율은 6:4 고정시키고, 음전압은 -150V에서 -750V까지, -150V씩 증가하여 바이어스 전압의 변화에 따른 필름의 특성을 분석하였다. 바이어스 전압을 증가시킴에 따라 수소의 함량은 48.8 at.%에서 20.3 at.%로, Si의 함량은 1.5 at.%에서 2.4 at.%로 증가하였다. 그리고 잔류응력은 0.5GPa에서 2.1GPa로 증가하였고, 경도의 경우 5GPa에서 21.5GPa로 증가하는 경향을 보였다. 이러한 경향은 필름내부의 3차원 상호결합과 이온의 충돌에너지의 영향임을 알 수 있었다.

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Establishment of Safety Factors for Determining Use-by-Date for Foods (식품의 소비기한 참고치 설정을 위한 안전계수)

  • Byoung Hu Kim;Soo-Jin Jung;June Gu Kang;Yohan Yoon;Jae-Wook Shin;Cheol-Soo Lee;Sang-Do Ha
    • Journal of Food Hygiene and Safety
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    • v.38 no.6
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    • pp.528-536
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    • 2023
  • In Korea, from January 2023, the Act on Labeling and Advertising of Food was revised to reflect the use-by-date rather than the sell-by-date. Hence, the purpose of this study was to establish a system for calculating the safety factor and determining the recommended use-by-date for each food type, thereby providing a scientific basis for the recommended use-by-date labels. A safety factor calculation technique based on scientific principles was designed through literature review and simulation, and opinions were collected by conducting surveys and discussions including industry and academia, among others. The main considerations in this study were pH, Aw, sterilization, preservatives, packaging for storage improvement, storage temperature, and other external factors. A safety factor of 0.97 was exceptionally applied for frozen products and 1.0 for sterilized products. In addition, a between-sample error value of 0.08 was applied to factors related to product and experimental design. This study suggests that clearly providing a safe use-by-date will help reduce food waste and contribute to carbon neutrality.

Dimerization of Aquooxomolybdenum (V) ion in Acid Media (I). Dehydrogenation of Bridging Hydroxide of $Mo_2O_4(OH)_{2(aq)}^{4+}$ (산성용액에서 아쿠오옥소몰리브덴 (V) 이온의 이합화 반응 (I). 이합체 착물의 두다리인 히드록소의 탈수소화 반응)

  • Chang-Su Kim;Chann-Woo Kim;Chang-Yong Kwon;Moon-Pyoung Yi
    • Journal of the Korean Chemical Society
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    • v.29 no.5
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    • pp.510-515
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    • 1985
  • Color of $MoO_{(aq)}^{3+}$ in concentrated methanesulfonic acid (∼10M) changes dark green due to the formation of $Mo_2O_2(OH)_{2(aq)}^{4+}$ dimer. This color is similar to that shown by addition of water to that shown by addition of water to green $MoO_{(aq)}^{3+}$ solution in 15-16M methanesulfonic acid. The molar extinction coefficient of monomer in 15M methanesulfonic acid is about 20 at 415nm. Rate constants are independent on the aquomolybdenum (V) and hydrogen ion concentration under the condition of this experment. Bridging hydroxides of $Mo_2O_2(OH)_{2(aq)}^{4+}$ are dehydrogenated at the less concentration of ∼6 M for HPTS and ∼10M for $CH_3SO_3H$. The structure of both the yl-oxygens and the bridging oxygens of final product is identified to (*image)unit.

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Adsorption of Trace Metals on the Natural Amorphous Iron Oxyhydroxide from the Taebag Coal Mine Area (태백 탄전 지대의 비정질 철 수산화물에 대한 희귀원소의 흡착)

  • Yu, Jae-Young;Park, In-Kyu
    • Journal of the Korean Society of Groundwater Environment
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    • v.1 no.1
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    • pp.23-32
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    • 1994
  • To determine the apparent equilibrium constants, K$_{ad,app}$, for the adsorption reactions of trace metals on amorphous iron oxyhydroxide (AIO) in the Taebag coal mine area, time-adsorption and pH-adsorption experiments were performed for a selected bottom sediment mainly comprised of AIO from the study area. The results from the adsorption experiments indicate that most of the trace metals, except Pb, achieve equilibrium states with AIO and thus, the calculated K$_{ad,app}$ may represent the true apparent equilibrium constants. K$_{ad,app}$ and the stoichiometric coefficients of proton, x, of the adsorption reactions between the trace metals and AIO were respectively calculated from the intercepts and slopes of the regression lines of log($\Gamma$/ [M]$_{aq}$)against pH provided by pH-adsorption experiments. The calculated K$_{ad,app}$ this study has the values of the range from 10$^{-4.5}$ to 10$^{2.75}$ , which is much different from the reported values by other investigators for simple experimental systems. K$_{ad,app}$ of this study is more or less close but not exactly pertinent to the estimated values for the other natural systems. It indicates that K$_{ad,app}$ for the adsorption reactions in the aquatic system in the study area is unique and thus should be determined befor the adsorption modelling. The calculated x of this study has the values of the range from -0.3 to 0.7, which is also much different from what most geochemists generally accept. The discrepancy in x may be due to the competition among different kinds of ionic species on the adsorption site or simulataneous occurrence of different kinds of adsorption reactions. The results from this study should help construct an appropriate adsorption model for the aquatic systems polluted by the coal mine drainage in the Taebag area. With the constructed model, one can describe the concentration variations of trace metals due to the adsorption in the system, which is an essential part of the investigation on the water quality affected by coal mine drainage in the Taebag coal field.

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Electrochemical Behavior of a Nickel Hydroxide Particle for Ni-MH Battery by Microelectrode (마이크로전극에 의한 니켈수소전지용 수산화니켈 입자의 전기화학적 거동)

  • Kim, Ho-Sung;Oh, Ik-Hyun;Lee, Jong-Ho
    • Journal of the Korean Electrochemical Society
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    • v.10 no.2
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    • pp.145-149
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    • 2007
  • Electrochemical studies were performed for a single particle of nickel hydroxide for the cathode of Ni-MH batteries. A carbon fiber microelectrode was manipulated to make electrical contact with an alloy particle, and electrochemical experiments were performed. As a result of cyclic voltammetry, the oxidation/reduction and oxygen evolution reaction (OER) are clearly separated for a single particle. The total cathodic charge (Qred) is practically constant for the scan rate investigated, indicating that the whole particle has reacted. The total anodic charge(Qox) was larger than that of reduction reaction, and the magnitude of oxygen evolution taking place as a side reaction was enhanced at lower scan rates. As a result of galvanostatic charge and discharge measurement, the discharge capacity of single particle was found to be 250 mAh/g, value being very close to the theoretical capacity (289 mAh/g). The apparent proton diffusion coefficient(Dapp) using potential step method inside the nickel hydroxide was found to range within $3{\sim}4{\times}10^{-9}\;cm^2/s$.