• Corrosion Science and Technology
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• 제7권1호
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• pp.35-39
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• 2008

We have been studying application of electrochemical noise (Fluctuation) analysis for localized corrosion. Foils of Zinc, Aluminum and Magnesium were used as specimens for electrochemical cell simulating localized corrosion. These specimens were dipped in sodium chloride solutions adjusted to each exponent of Hydrogen ion concentration (pH) condition of 5.5, 10, 12 respectively. Time variations of potential and current were measured in those solutions, and simultaneously the surfaces of specimens were observed using microscope with television monitor. Two types of electrochemical cells were arranged for experiments simulated localized corrosion. The fluctuations on trendy component of short-circuited potential and short-circuited current were appeared in synchronization. It was seemed that these fluctuations result from hydrogen evolution on the aluminum active site in the crevice from the microscopic observation. In the case of zinc and magnesium, fluctuations appeared on the trendy component of the corrosion potential. Two types fluctuation were detected. First one is the fluctuation varied periodically. The second one is the random fluctuation. It was seemed that these fluctuations result from generation of corrosion products and hydrogen evolution on the active site in the crevice of zinc and magnesium from the microscopic observation.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• 제3권1호
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• pp.41-47
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• 2005

Preparation of ferrocyanide-anion exchange resin and adsorption test of the prepared resin on the Cs$^{+}$$ion were performed. Adsorption capability of the prepared resin on the Cs$^{+}$ion in the simulated citric acid based soil decontamination waste solution was 4 times greater than that of the commercial cation exchange resin. Adsorption equilibrium of the prepared resin on the Cs$^{+}$ion reached within 360 minutes. Adsorption capability on the Cs$^{+}$ion became to decrease above the necessary Co$^{2+}$ion concentration in the experimental range. Recycling test of the spent ion exchange resin by the successive application of hydrogen peroxide and hydrazine was also performed. It was found that desorption of Cs$^{+}$ion from the resin occurred to satisfy the electroneutrality condition without any degradation of the resin.

• Journal of the Korean Chemical Society
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• 제34권6호
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• pp.561-568
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• 1990

Voltammetric behavior of some light lanthanide ions (La$^{3+}$, Pr$^{3+}$, Nd$^{3+}$, Sm$^{3+}$, and Eu$^{3+}$) in various supporting electrolytes has been investigated by several electrochemical techniques. The peak potentials and the peak currents, their dependency on the concentration, temperature and pH effects, the reversibility of the electrode reactions are described. The reduction of La$^{3+}$, Pr$^{3+}$ and Nd$^{3+}$ in 0.1 M lithium chloride proceeds by a three-electron change directly to the metallic state (Ln$^{3+}$ ＋ 3e- → Ln$^0$) and charge transfer is totally irreversible. However, the reduction of Sm$^{3+}$ in 0.1 M tetramethylammonium iodide and Eu$^{3+}$ in 0.1 M lithium chloride proceeds in two stages (Ln$^{3+}$ ＋ e- → Ln$^{2+}$ and Ln$^{2+}$ ＋ 2e- → Ln$^0$). At pH values lower than ca.4 the hydrated lanthanide species (Ln(OH)$^{2+}$) reduced before the lanthanide ions (Ln$^{3+}$) due to the catalytic effect of hydrogen ions, and peak current increase with in the order Eu$^{3+}$ < Sm$^{3+}$ < Nd$^{3+}$ < Pr$^{3+}$ < La$^{3+}$ in differential pulse polarography. Some representative plots of $i_{pc}V^{-1/2} (proportional to current function) vs. V show considerable influence of hydrogen ion/lanthanide ion concentration in cyclic voltammetry. It is shown that a reaction of lanthanide ions with proton and/or water and catalytic reaction is enhanced at lower pH and at decreased lanthanide ion concentration.

• Journal of the Korean Chemical Society
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• 제46권6호
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• pp.509-514
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• 2002

A method to determin Fe(II) and Fe(III) ion in aqueous solution by chemiluminescence method using a stopped flow system has been studied. The method is based on the increased chemiluminescence intensity with the addition of Fe(III) ion to a solution of lucigenin and hydrogen peroxide. The effects of KOH concentration, flow rate of reagents, $H_2O_2$ concentration and citric acid concentration used for the masking of Fe(II) ion on the chemilu-minescence intensity have been investigated. The calibration curve for total Fe was linear over the range from 1.0${\times}$$10^{-6}$ M to 1.0${\times}$$10^{-4}$M, coefficient of correlation was 0.996 and the detection limit was 1.0${\times}$$10^{-7}$M under the optimal exper-imental conditions of 4.0 M, 2.0 M, 3.5 mL/min for the concentration of $H_2O_2,$ KOH and flow rate of reagents, respec-tively. The calibration curve for Fe(Ⅲ) was linear over the range from 1.0${\times}$$10^{-6}$M to 1.0${\times}10^{-4}$ M, the coefficient of correlation was 0.997 and the detection limit was 5.0${\times}$$10^{-7}$M under the optimal experimental conditions.

• Bulletin of the Korean Chemical Society
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• 제35권4호
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• pp.1023-1028
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• 2014

Protonated caffeine ($CH^+$) and glucosamine ($GH^+$) overlapped in an analysis with ion mobility spectrometryquadrupole mass spectrometry. Ethyl lactate vapor (L) at different concentrations from 0 to 22 mmol $m^{-3}$ was added as a buffer gas modifier to separate these signals. The drift times of $CH^+$ and $GH^+$ increased with L concentration. The drift time increase was associated to clustering equilibria of $CH^+$ and $GH^+$ with one molecule of L and the equilibrium of $GH^+$ was more displaced to the formation of $GLH^+$ than that of $GLH^+$. $GH^+$ clustered more to L than $CH^+$ because $GLH^+$ formed more stable hydrogen bonds (26.30 kcal/mol) than $GLH^+$ (24.66 kcal/mol) and the positive charge in $GH^+$ was more sterically accessible than in $CH^+$. The aim of this work was to use theoretical calculations to guide the selection of a buffer gas modifier for IMS separations of two compounds that overlap in the mobility spectra and predict this separation, simplifying that empirical process.

• Journal of the Korean GEO-environmental Society
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• 제12권12호
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• pp.21-30
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• 2011

The recycled soil that is proceeded from demolition concrete structures was analyzed by the methods of the physical and mechanical tests of soil and TCLP test to use the soil in low landfilling for the construction of an industrial complex. The laboratory test for diffusion of alkali ion in soil mass was analyzed by the methods of XRF and ICP. The fish toxicity test was also conducted to find an environmental influence. The recycled soil through the laboratory test satisfied the engineering property for low landfilling and the criteria of soil contamination. However, the solution which producted by 1:1 ratio of recycled soil and water contained the high pH concentration by alkali ion. The calcium hydroxide solution by CSH cement paste was estimated as the main reason why pH concentration is increased more than 9.0. The high pH concentration in recycled soils causes a toxicity to the livability of fishes. A diffusion area of pH concentration in the ground was analyzed by the Visual Modflow Ver. 2009 program based on geotechnical investigation. The high pH concentration in the recycled soils can be remained as high value due to cement paste in the long term period. Therefore, in the early stage of landfilling work, the mixing with the weathered granite soil is necessary to control the pH concentration.

• The Korean Journal of Physiology and Pharmacology
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• 제17권3호
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• pp.181-187
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• 2013

Reactive oxygen species (ROS) are generated in various cells, including vascular smooth muscle and endothelial cells, and regulate ion channel functions. $K_{Ca}3.1$ plays an important role in endothelial functions. However, the effects of superoxide and hydrogen peroxide radicals on the expression of this ion channel in the endothelium remain unclear. In this study, we examined the effects of ROS donors on $K_{Ca}3.1$ expression and the $K^+$ current in primary cultured human umbilical vein endothelial cells (HUVECs). The hydrogen peroxide donor, tert-butyl hydroperoxide (TBHP), upregulated $K_{Ca}3.1$ expression, while the superoxide donors, xanthine/xanthine oxidase mixture (X/XO) and lysophosphatidylcholine (LPC), downregulated its expression, in a concentration-dependent manner. These ROS donor effects were prevented by antioxidants or superoxide dismustase. Phosphorylated extracellular signal-regulated kinase (pERK) was upregulated by TBHP and downregulated by X/XO. In addition, repressor element-1-silencing transcription factor (REST) was downregulated by TBHP, and upregulated by X/XO. Furthermore, $K_{Ca}3.1$ current, which was activated by clamping cells with 1 ${\mu}M$ $Ca^{2+}$ and applying the $K_{Ca}3.1$ activator 1-ethyl-2-benzimidazolinone, was further augmented by TBHP, and inhibited by X/XO. These effects were prevented by antioxidants. The results suggest that hydrogen peroxide increases $K_{Ca}3.1$ expression by upregulating pERK and downregulating REST, and augments the $K^+$ current. On the other hand, superoxide reduces $K_{Ca}3.1$ expression by downregulating pERK and upregulating REST, and inhibits the $K^+$ current. ROS thereby play a key role in both physiological and pathological processes in endothelial cells by regulating $K_{Ca}3.1$ and endothelial function.

• Journal of Soil and Groundwater Environment
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• 제11권6호
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• pp.76-82
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• 2006

Fenton's reaction are difficult to apply in the field due to the low pH requirements for the reaction and the loss of reactivity caused by the precipitation of iron (II) at neutral pH. Moreover, Fenton-like reactions using iron mineral instead of injection of iron ion as a catalyst are operated to get high removal result at low pH. Because hydroxyl radical can generate at the surface of iron mineral, there are competition with a lot of hydroxide at around neutral pH. On the other side, to operate Fenton's reaction series at neutral pH, modified Fenton reaction is suggested. The complexes, composed by iron ions (ferrous ion or ferric ion)-chelating agent, could be acted as a catalyst and presented in the solution at neutral pH. However, modified Fenton reaction requires a lot of hydrogen peroxide. Accordingly, the purpose of this experiment was to effectively combine Fenton-like reaction and modified Fenton reaction for extending application of Fenton's reaction. i.e., injecting chelating agents in Fenton-like reaction at around neutral pH is increasing the concentration of dissolved iron ion and highly promoting the oxidation effect. 2,4,6-trinitrotoluene (TNT) was used as a probe compound for comparing reaction efficiencies in this study. If the concentration of dissolved iron ion in combined Fenton process were existed more than 0.1 mM, the total TNT removal were increased. Magnetite-NTA system showed the best TNT removal (76%) and Magnetite-EDTA system indicated about 56% of TNT removal. The results of these experiments proved more promoted 40-60% of TNT removal than Fenton-like reaction's.

• Korean Journal of Environmental Agriculture
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• 제20권5호
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• pp.352-357
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• 2001

Cadmium (Cd) has been identified as a potential contaminant in agricultural and environmental soils. Ionic condition in the soils is an important factor to influence Cd availability. In this study, the effect of sulfate or nitrate application on Cd sorption in acidic and calcareous soils was investigated. The Cd, sulfate $(SO_4)$, and nitrate $(NO_3)$ sources were solutions of $CdCl_2$, $K_2SO_4$, and $KNO_3$, respectively. The soil-solution system pH was affected by the application of sulfate or nitrate in both acidic and calcareous soil system, but there was not clear pH difference between pre- and simultaneous applications of sulfate or nitrate (PAS/PAN or SAS/SAN). Solution ionic strength (I) values were similar between the acid and calcareous soil systems after applying the Cd even though it was significantly different in the untreated control soils. However after applying the sulfate or nitrate, the I values increased and were always higher with SAS/SAN treatments. Solution Cd concentration also increased with the application of sulfate or nitrate. However, the Cd concentration in soil solution controlled by Cd sorption in the systems was different between PAS/PAN and SAS/SAN treatments only in the calcareous soil system, but not in the acidic soil system. The difference in Cd concentration between SAS/SAN and PAS/PAN in the calcareous systems may be caused by system pH, ionic strength, complexation, and predominately, competition of the $Cd^{2-}$ with the index $K^+$ ion. Potassium ion-Cd competition in the acidic soil system may be minimized because of the abundance of hydrogen ions.

• Journal of Sensor Science and Technology
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• 제10권4호
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• pp.259-265
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• 2001

FET-type dissolved oxygen sensor has the Pt working electrode around the pH-ISFET. Appling a voltage to the working electrode, the hydrogen ion which is proportional to the dissolved oxygen concentration occurs around the pH sensing gate and we can measure the dissolved oxygen concentration by detecting pH concentration through the pH-ISFET. In this paper, a dissolved oxygen measurement system using FET-type dissolved oxygen sensor array which adopt a specific algorithm to enhance the reliability has been developed and we compared its performance with the commercial dissolved oxygen measurement system.