• Corrosion Science and Technology
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• v.7 no.1
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• pp.45-49
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• 2008

The cyclic polarisation technique was applied to determine the corrosion, primary-passivation, transpassive, and protection potential of AISI 316L stainless steels immersed in 3550-ppm NaCl solution containing sulfate in the content up to 3000 ppm. The solutions were kept constant at $27^{\circ}C$ and saturated by laboratory air. The solution pH was varied from 3 to 11. Each type of potentials was plotted in function of pH and linked as lines to determine the different zones in the constructed potential-pH diagram. The predominant regimes of the immunity, general corrosion, perfect passivation, imperfect passivation, and pitting corrosion were determined based on those lines of potentials. Comparing to the potential-pH diagram of specimens immersed in the aerated and deaerated 3550-ppm NaCl solutions, the addition of 3000-ppm $Na_2SO_4$ to these solutions increased the overall, perfect and imperfect, passivation regime by shifting the transpassive-potential line to the noble direction. However, it also widened the imperfect passivation area. The addition of $Na_2SO_4$ did not significantly affect the corrosion potential. It was found that the dissolved oxygen tends to negatively shift the transpassive-potential and protection-potential lines at all studied pH. The considerable effect of dissolved oxygen on corrosion and primary-passivation potentials could not be observed.

• Journal of Radiation Protection and Research
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• v.27 no.2
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• pp.95-100
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• 2002

Conventional and modified electrolytic decontamination experiment were performed in the 1.7 M solution of sodium sulfate and sodium nitrate tot decontamination of carbon steel as the simulated metal wastes which have been produced in large amounts from nuclear power plants. Anode ant cathode were used as inconel and titanium respective. The reaction time and temperature were 1 hr and $25^{\circ}C$ The analyses were performed of the characteristics such as weight loss arid thickness change of metal waste. suspended solid in electrolyte and SEM observation. In modified electrolyte decontamination system with increased current density ranged from 0.1 to $0.6A/cm^2$, the metal waste showed thickness changes of $0.48{\pm}0.005$ to $67.7{\pm}0.02{\mu}m$ in 1.7 M sodium sulfate and those of $0.06{\pm}0.005$ to $17.7{\pm}0.05{\mu}m$ in sodium nitrate. Metal waste in modified electrolyte decontamination system showed the thickness change of $9.8{\pm}0.01{\mu}m$ while it reacted up to $3.7{\pm}0.03{\mu}m$ in conventional system with $0.3 A/cm^2$ of current density and 1.7 M sodium sulfate. Decontamination efficiencies of modified electrolytic process ate much hither than that of conventional electrolytic process when both are applied to metal waste.

• Bulletin of the Korean Chemical Society
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• v.20 no.4
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• pp.431-435
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• 1999

An organic precipitate flotation of Cd(Ⅱ) and Pb(Ⅱ) was investigated by the coprecipitation with lanthanum 8-hydroxyquinolinate. Trace amounts of Cd(Ⅱ) and Pb(Ⅱ) with a significantly large amount of La(Ⅲ) were simultaneously precipitated in a 1,000 mL sample solution with the ethanolic 8-hydroxyquinoline solution. The pH was adjusted to 9.0 with 2 M ammonia solution. The precipitates were floated with the aid of tiny nitrogen bubbles and supported by the stable foam layer of sodium lauryl sulfate. The floats were collected on the fritted glass filter by a suction. The material collected was dissolved with 5.0 mL of ethanol and 1.5 mL of concentrated nitric acid, and then diluted to 25.0 mL with a deionized water. The analytes were determined by a flame atomic absorption spectrophotometry. The recoveries of the analytes spiked in the sample were 94.8% for Pb(Ⅱ) and 92.0% for Cd(Ⅱ). This flotation technique is simple and rapid, and also applicable to the determination of trace Cd(Ⅱ) and Pb(Ⅱ) at lew ppb levels.

• YAKHAK HOEJI
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• v.13 no.2_3
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• pp.84-87
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• 1969

Microanalysis of organic sulfur compounds by means of combining thin layer chromatography and oxygen combustion flask method was attempted. The following procedure was found to be very simple and to give accurate results. The mixture of sulfa drugs was separated with T.L.C., and it was burned in a flask filled with oxygen, and the gas formed was absorbed in a dilute solution of sodium hydroxide. The solution was neuralized with hydrochloric acid and heated in a water bath. The sulfate ion formed was then treated with barium chromate solution and its absorbancy at 370 m.mu. was measured.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.1
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• pp.1-7
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• 2005

Anion exchange chromatography and HDEHP extraction chromatography using DTPA-lactic acid as an eluent were applied in series for the separation of $^{241}$Am and $^{244}$Cm in radwaste samples. The separated elements were determined by electrodeposition at the sodium hydrogen sulfate-sodium sulfate buffer solution followed by alpha-spectrometry. The recovery yields of $^{241}$Am and $^{244}$Cm were 85.2$\pm$$15.3\%$, respectively, from the synthetic solution of spent nuclear fuel sample. The amounts of 241Am and 2440m determined in radwaste sample solutions of condensate bottoms were at the range of 1.5-1.9 Bq/g and -1.7 Bq/g, respectively.

• Journal of Soil and Groundwater Environment
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• v.13 no.5
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• pp.74-80
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• 2008

Heavy metals, Cd and Pb, in soil were extracted by using anionic surfactants such as AOS (alpha olefin sulfonate), SDS (sodium dodecyl sulfate), and LAS (linear alkyl benzene sulfonic acid). Metal extractability from soil was affected by the carbon number and solution pH of surfactants. LAS showed higher metal extractability due to the acidic solution condition. Although SDS has a fewer carbon number than AOS, it would produce smaller micelles and resulted in more efficient extraction of metals by increased soil contact. Cd extractability of surfactant was twice enhanced by adding NaI as a ligand. However, Pb extractability of surfactant was sometimes reduced by adding NaI. Those ligand effects were dependent on solubility of metal-ligand. The column experiment also showed that SDS having smaller micelles resulted in higher metal extractability than AOS.

• Journal of the Korean Chemical Society
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• v.37 no.10
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• pp.855-860
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• 1993

In the presence of SDS(sodium dodecyl sulfate), effect of $Ca^{2+}$on the interaction of NP-40EO[nonylphenol-(ethylene oxide)40] with iodine in aqueous solution were investigated by UV-visible spectrophotometer. In the presence of SDS, the intensity of interaction peaks were decreased and markedly increased by the addition of $Ca^{2+}$. Decrease of interaction peaks is caused by decrease of EO number to be interact with iodine per unit surface area of mixed micelle to the insertion of SDS and increase is attributed to the compactness of micelle in the presence of $Ca^{2+}$. These phenomena may be explained by the fact that the linear EO (ethylene oxide) chains, to be free in aqueous solution, could form a pseudo-crown ether structures of forming with $Ca^{2+}$ion.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.5
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• pp.55-64
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• 2008

Shotcrete have become a deterioration which was exposed to harmful environments. In this study, in order to evaluate the deterioration properties of shotcrete, visual examination, compressive strength, adhesive strength, microstructural analysis were investigated up to the 60th weeks of exposure. The attack solutions for test are sodium sulfate and hydrochloric acid solution with different concentrations, respectively. From the results, although the compressive strength of shotcrete specimens and the adhesive strength between specimens and rocks were high at the early immersion age, they rapidly dropped in the subsequent phases, especially in 5% sodium sulfate and pH1 hydrochloric acid solution. With continued exposure, various harmful ions penetrated into the shotcrete specimen, reacted with the cement hydrate, and generated expansion substances. It was verified that the shotcrete specimens suffered a serious deterioration by chemical attack.

• Natural Product Sciences
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• v.10 no.6
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• pp.262-267
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• 2004

A reversed-phase liquid chromatographic method for decursin and decursinol angelate of Angelicae gigantis Radix, an important crude drug in Korean traditional medicine, was developed and validated. Decursin and decursinol angelate, the structure isomer (pyranocoumarin) each other, are the main organic constituents in Angelicae gigantis Radix. This method was developed using a RP-18 column, UV detector at 280 nm and 50% acetonitrile solution containing 0.01 M sodium dodecyl sulfate and 25 mM sodium dihydrogen phosphate (pH 5.0) as the mobile phase. Various validation parameters were included and evaluated satisfactorily. Linearity was established in range 2-75 mg/ml of decursin and decursinol angelate (correlation coefficient = 0.9997 and 0.9995, respectively). This analytical method showed good accuracy (98.1% and 99.5%, respectively). Precision (repeatability) revealed a relative standard deviation value of 1.71% (decursin) and 3.19% (decursinol angelate). For intermediate precision measure the considered variables were equipment and days. A robustness test showing the influence of deferent counter-ion concentration in mobile phase was also performed.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.5
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• pp.275-278
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• 2003

Antioxidative activity is an important factor in inhibiting oxidative stress. The usual methods for determining antioxidative activity are time-consuming and cumbersome. They are also indirect processes that use biological material such as brain or liver microsome. This study therefore proposed a new method. Redoxpotential was determined using galvanic cell with or without the addition of various antioxidants or herbal extracts in zinc sulfate solution. The result was compared with the results from the TBA method and the peroxide value from sodium thiosulfate titration. All methods showed significant and dose-dependent enhancement of antioxidative activity by adding ascorbic acid, quercetin, ginseng, or gingko biloba extract. The result of redox potential using galvanic cell showed the smallest standard deviation and took the shortest time among the three methods. Therefore, the antioxidative potential of chemical substances and herbal extracts can be determined simply, directly and accurately in a short period of time using galvanic cell.