• Bulletin of the Korean Chemical Society
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• v.25 no.7
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• pp.1019-1024
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• 2004

The present paper is focused on simultaneous sorption concentration of gold (III) and silver (I) from thiocyanate solutions using high-selective anion exchanger AN-25 and subsequent separation of these ions at various concentrations of thiocarbamide (eluent). As a result, silver (I) ions are completely eluted from AN-25 and gold (III) ions remain in the resin phase and can be determined directly in the solid phase by diffuse reflection spectroscopy. It is proposed to use the sorption-spectroscopic method for Au(III) determination in aqueous solutions. The calibration curve is linear in the concentration range of 1-19 mg/L (sample volume is 10.0 mL) and the detection limit is 0.05 ${\mu}g/mL$. The presence of Cu(II), Co(II), Fe(II) do not hinder this determination. Au(III) was determined in industrial solutions.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.236.2-236.2
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• 2015

The copper-zinc(Cu-Zn) nanofiber was prepared by electrospinning method. The Cu/PVP (polyvinylpyrrolidone) and Zn/PVP precursor solutions were prepared by dissolution of copper sulfate and zinc acetate in methanol, respectively. The PVP was used to control the viscosity of the precursor solutions. The optimized ratio for the Cu/PVP and Zn/PVP nanofibers was determined separately. Then the suitable ratio of the precursor solutions was applied for fabrication of Cu/Zn/PVP nanofiber. For the electrospinning method, the precursor solutions were filled in a syringe. The distance between metallic needle on the syringe and collector was fixed at 16 cm and the voltage was applied on the tip was 13.0 kV. And the as-spun nanofiber was heated at 353K for removal of residual solvent. Then the heated nanofibers were calcined at 973K to decompose PVP. The obtained Cu, Zn, and Cu-Zn nanofibers were investigated with X-ray photoelectron spectroscopy (XPS) for the chemical properties, scanning electron microscopy (SEM) for the morphologies, and X-ray diffraction (XRD) to characterize the crystallinity and phase of nanofibers.

• Bulletin of the Korean Chemical Society
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• v.12 no.4
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• pp.383-387
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• 1991

A new perturbation theory called as star expansion method is used to obtain the nonlinear retarded solution of the Schlogl models with some kinds of external input. The approximate nonlinear solutions are compared with the exact solution, linear solutions, and those obtained by the Feynman method.

• Bulletin of the Korean Chemical Society
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• v.10 no.2
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• pp.148-151
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• 1989

The hydrophobic interaction between tetraphenylborate (TPB$^-$) or tetrakis (4-fluorophenyl)borate (TFB$^-$) and crystal violet has been investigated in aqueous solutions by absorption spectrophotometry. Both of the anions promote the aggregation of the ion pairs formed between crystal violet and TPB$^-$ or TFB$^-$. When crystal violet and borate anion are nearly equimolar, insoluble floating aggregates can be observed. Based on the relative absorbance of H and J bands and on the effect of TX-100, TFB$^-$ is found to be more hydrophobic than TPB$^-$.

• Bulletin of the Korean Chemical Society
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• v.13 no.3
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• pp.248-252
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• 1992

$ZrO_2-dopedYb_2O_3solid$ solutions containing 1, 3, 5, 7 and 9 mol% $ZrO_2were$ synthesized from spectroscopically pure $Yb_2O_3$ and $ZrO_2$ powders and found to be rare earth C-type structure by XRD technique. Electrical conductivities were measured as a function of temperatures from 700 to $1050^{\circ}C$ and oxygen partial pressures from 1${\times}$$10^-5$ to 2${\times}$ $10^-1$atm. The electrical conductivities depend simply on temperature and the activation energies are determined to be 1.56-1.68 $_eV$. The oxygen partial pressure dependence of the electrical conductivity shows that the conductivity increases with increasing oxygen partial pressure, indicating p-type semiconductor. The $PO_2$ dependence of the system is nearly power of 1/4. It is suggested from the linearity of the temperature dependence of electrical conductivity and only one value of 1/n that the solid solutions of the system have single conduction mechanism. From these results, it is concluded that the main defects of the system are negatively doubly charged oxygen interstitial in low. $ZrO_2doping$ level and negatively triply charged cation vacancy in high doping level and the electrical conduction is due to the electronic hole formed by the defect structure.

• Bulletin of the Korean Chemical Society
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• v.13 no.2
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• pp.127-131
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• 1992

Changes in network structures of ${\alpha}-Nb_2O_5$ in the X MgO+(1-X) ${\alpha}-Nb_2O_5$ solid solutions occurring as the MgO doping level (X) was varied were investigated by means of infrared spectroscopy and X-ray analysis. X-ray diffraction revealed that all the synthesized specimens have the monoclinic structure. The FT-IR spectroscopy showed that the system investigated forms the solid solutions in which $Mg^{2+}$ ions occupy the octahedral sites in parent crystal lattice. Electrical conductivities were measured as a function of temperature from 600 to $1050{\circ}$ and $P_{O2}$ form $1{\times}10^{-5}$ to $2{\times}10^{-1}$ atm. The defect structure and conduction mechanism were deduced from the results. The $1}n$ value in ${\alpha}{\propto}{P_{O2}^{1}n}}$ is found to be -1/4 with single possible defect model. From the activation energy ($E{\alpha}$ = 1.67-1.73 eV) and the1/n value, electronic conduction mechanism is suggested with a doubly charged oxygen vacancy.

• Bulletin of the Korean Chemical Society
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• v.14 no.1
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• pp.146-149
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• 1993

• Bulletin of the Korean Chemical Society
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• v.9 no.6
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• pp.413-414
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• 1988

• Bulletin of the Korean Chemical Society
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• v.14 no.3
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• pp.363-366
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• 1993

• Journal of the Korean Chemical Society
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• v.14 no.3
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• pp.263-269
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• 1970

A theory of surface tension developed by using the approximation that the surface of liquids consists of a monomolecular layer has been applied to the molten salts (NaCl, KCl, NaBr, KBr) and the strong electrolyte solutions. By considering that the ionic forces are the long-range forces and with the use of the partition functions developed, the surface tension of molten salts and strong electrolyte solutions has been calculated. The results show good agreement between theory and experiment at various temperatures and over a wide concentration ranges (0.1-4.0m)