• Journal of the Korean Chemical Society
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• v.18 no.4
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• pp.272-277
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• 1974

A relationship between the activity coefficients of tri-n-butylphosphate(TBP) and europium complex was studied in the extraction of europium by TBP in nitric acid solution. Diluents chosen are cyclohexane, toluene, benzene and chlorobenzene. Concentrations of TBP were varied from 5 to 50 by volume percent and the composition of inorganic layer was kept constant. A method of estimating the solubility parameter of TBP is suggested.

• Bulletin of the Korean Chemical Society
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• v.21 no.11
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• pp.1085-1089
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• 2000

The effect of 2-hydroxyacetophenone-aroyl hydrazone derivatives on the inhibition of copper corrosion in 3N nitric acid solution at 303 K was investigated by galvanostatic polarization and thermometric techniques. A significant decrease in the cor rosion rate of copper was observed in the presence of the investigated compounds. The corrosion rate was found to depend on the nature and concentrations of the inhibitors. The degree of surface coverage of the adsorbed inhibitors is determined from polarization measurements, and it was found that the results obey the Frumkin adsorption isotherm. The inhibitors acted as mixed-type inhibitors, but the cathode is more polarized. The relative inhibitive efficiency of these compounds has been explained on the basis of structure dependent electron donor properties of the inhibitors and the nature of the metal-inhibitor interaction at the surface. Also, some thermodynamic data for the adsorption process ( ΔGa* and f ) are calculated and discussed.

• 한국전기화학회:학술대회논문집
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• 1998.10a
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• pp.39-39
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• 1998

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.455.1-455
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 1999.05a
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• pp.305-305
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• 1999

• Proceedings of the Membrane Society of Korea Conference
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• 2005.11a
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• pp.152-156
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• 2005

• Economic and Environmental Geology
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• v.53 no.2
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• pp.183-196
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• 2020

This study aimed to recover native gold from the concentrate using microwave-nitric acid leaching and magnetic/hydro separation experiments. The insoluble-residue was filtered from leaching solution through microwave-nitric acid leaching experiment. As a result of the atomic absorption spectrometer(AAS) analysis of the filtered leaching solution, it was discovered that Au content was not eluted at all and it was observed from the back scattered electron(BSE) image that native gold was liberated in the insoluble-residue. When magnetic/hydro separation experiments were applied for the insoluble-residue, magnetic and non magnetic minerals were separtated from insoluble-residue. Magnetite was recovered from the magnetic minerals and as a result of applying the hydro separation experiment again for the non-magnetic mineral, native gold was recovered. The native gold was identified through the X-ray diffraction(XRD) analysis and BSE image.

• Environmental Analysis Health and Toxicology
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• v.29
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• pp.10.1-10.6
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• 2014

Objectives Cigarette smoking had been recorded as the main cause of impaired endothelium-dependent vasodilation in smokers by reducing nitric oxide (NO), a production of endothelial nitric oxide synthase (eNOS). However, the mechanism of NO impairment via eNOS activity is unclear until now. In this study, cell passage is suggested to be a relevant factor to eNOS expression under cigarette smoking stress. Methods Bovine aortic endothelial cells (BAECs) were chosen as the research subject with passages ranking from 6 to 9 (6P to 9P). After exposure of cigarette smoking extract (CSE) solution, MTT assay and Western blot method were performed to check the cell viability as well as eNOS protein concentration. In these experiments, four concentrations of CSE at 0.5, 1, 2, and 4% were selected for treatment. Results Our results showed that cells almost died at 4% of CSE. Besides, eNOS protein mass had a linear decrease under the increase of CSE concentration. In addition, the effect of CSE on eNOS expression was dissimilar between different passages. Conclusions This study indicated that CSE had effect on both cell viability and eNOS expression. Besides, a reduction in protein mass was matched with the decrease of cell viability due to CSE tress. Last but not least, the response of eNOS protein to different concentration of CSE at different passages was disparate, making the hypothesis about cell passage related inhibition of eNOS caused by CSE solution.

• Resources Recycling
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• v.18 no.5
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• pp.26-36
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• 2009

A recovery process of Ruthenium from waste electronic scrap has been investigated by means of nitric acid leaching as a part of development for scrap pretreatment process to obtaining an optimum conditions for removal of removing various impurities such as Pb, Bi, Zn, Al, Bi, Ag Fe, Co, Zr, Si. From the experiments, 90% of Pb leached with 250 g/l pulp density in 10-15% nitric acid. Leaching behavior of Ba was also similar to that of the Pb, but those of other metal impurities, such as Zn, Al, Bi, Ag, Fe, Co, Zr, showed different behavior, in which the dissolution rate increased as the concentration of nitric acid in solution is increased up to the 10% $HNO_3$ in solution and then it was constant above 10% $HNO_3$ concentrations. Meanwhile, the dissolution of Ru in $HNO_3$ solution was less then 100ppm, and that the total content of Ru in undissolved residue scrap was resulted in an increment of 50%.

• Journal of Advanced Marine Engineering and Technology
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• v.13 no.2
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• pp.43-63
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• 1989

Various kinds of corrosion prevention methods have been developed. It is known that the method of electrochemical protection is more effective and economical than any other method on the large scale metal structures in corrosive solutions. Strong acid solutions such as nitric and sulfuric acid solutions are often used in industries, and the expensive stainless steel is almost exclusively used for the equipment that comes in contact with such acid solutions. However, it is more reasonable that carbon steel is used rather than stainless steel depending upon concentration of those acid solutions from the economical viewpoint. In this study, the typical strong acid solution such as nitric and sulfuric acid solutions are chosen for the experiment and the selected materials of specimen are the stainless steels of SUS 304L and SUS 316L, the carbon steels of SS 41, SM 50 and RA 32, and highly pure lead. Electrochemical protection diagrams can be drawn with data from the external cathodic and anodic polarization curves of SUS 304L, SUS 316L and SM 50 steels in 5-60% nitric acid solutions and from those polarization curves of SS 41, RA 32, SM 50 and SUS 316L steels, and highly pure lead in 2.5-98% sulfuric acid solutions at the slow scanning rate. The data obtained with using the determination method of the optimum cathodic protection potential, the Tafel extrapolation method and the characteristics of anodic polarization curves. The main results obtained from the diagrams are as follows: 1) In nitric acid solution : (1) Corrosion potentials exist in each of those corrosion zones on the stainless steels in the lower concentration than about 12% solutions and on the high tensile strength steels in the lower concentration than about 30% solutions, but the corrosion current (density) in each zone is small on the above mentioned former steels and large on the latter ones. (2) The stainless steels can be self-passivated in the higher concentration than 15% solutions, and the high tensile strength steels gives rise to the same phenomenon in the higher concentration than 35% solutions. (3) The stainless steels in the lower concentration than 60% solutions and the high tensile strength steels in the higher concentration than 35% solutions can be used without protection, but the latter steels must ve protected anodically in the lower conccentration than about 30% solutions. 2) In sufuric acid solution : (1) The carbon steels can be self-passivated in the higher concentration than 45% solutions, and the SUS 316L steel in higher concentration than 75% solutions and the lead in all concentration solutions also gives rise to the same phenomenon. (2) The lead in the lower concentration than 80% solutions and the SUS 316L steel in the higher concentration than 80% solutions can be used without protection. (3) The carbon steels in the higher concentration than 50% solutions also can be used without protecting economically, but the SUS 316L steel in the 20-70% solutions are considerably corrosive without protecting anodically.