• Proceedings of the Korea Air Pollution Research Association Conference
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• 1995.10a
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• pp.99-102
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• 1995

• Applied Biological Chemistry
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• v.1
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• pp.26-33
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• 1960

Organic mercurial fungicides, for seed treatments and dust formulations, has been increasingly used by farmers. Evaluation of the purity of organic mercurial fungicides has been performed by precipitation method at this laboratory. There are several methods for the an alyses of organic mercuric formulation, among which are (1) Precipitation met hod, (2) Volatilization method, (3) Volumetric method, and (4) Dithizon method. These methods, however, show some deffects in specificity (differentiation of organic form) and quantitativity. Polarography applied for the estimation of phenyl mercuric acetate was found to be simple, rapid and accurate. Tile fundamental method of polarography arid accuracy of analysis are discussed statistically and a satisfactory results was obtained.

• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.846-851
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• 1998

An experimental research on the preparation of zinc oxide fine particles in w/o emulsions was conducted. Precipitation solutions were zinc nitrate aqueous solutions with hexamethylenetetramine(HMTA) as precipitant. The precipitation solutions formed stable w/o emulsions with kerosine in the presence of Span 80. Homogeneous precipitation reaction occurred in the w/o emulsion after the resultant w/o emulsion was heated above the decomposition temperature of HMTA and zinc oxide particles were precipitated. In some case, zinc oxide particles of bi-modal distribution were obtained. However, zinc oxide fine particles of narrow particle size distribution could be obtained, even when the initial zinc concentration of precipitation solution and the conversion to zinc oxide are both higher that those in bulk homogeneous precipitation.

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.339-343
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• 2010

A series of $Ce_1Mg_xZr_{1-x}O_2$ (CMZO) mixed metal oxide with different molar ratio were prepared by simple co-precipitation method. The prepared materials were tested for their catalytic activity performance using Knoevenagel condensation of various aromatic aldehydes with barbituric acid under solvent-free condition in microwave. The best catalytic activity was obtained with CMZO (1:0.6:0.4). The synthesized materials were characterized by using XRD, FT-IR, SEM-EDS techniques.

• Bulletin of the Korean Chemical Society
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• v.31 no.9
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• pp.2488-2492
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• 2010

A method is described for the determination of the Po nuclides in a water sample. After the Po nuclides were purified from interfering elements in a water sample using a manganese dioxide precipitation followed by a solvent extraction method, the Po nuclides were deposited onto the silver plate. A large volume of the water sample was effectively pretreated with manganese dioxide precipitation method. To determine the optimum conditions for plating Po, the effects of the pH, volume, temperature and time on the Po deposition were investigated in hydrochloric acid solution. The investigated determination method of Po nuclides with solvent extraction was applied to a tap water sample.

• Journal of Powder Materials
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• v.15 no.5
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• pp.386-392
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• 2008

Silver particles were synthesized from silver nitrate by homogeneous precipitation and chemical reduction methods involving the intermediate silver cyanate. The obtained silver particles were characterized by XRD, SEM, TEM, and BET. Urea which could prevent the agglomeration of the reduced silver particles was used as a homogeneous precipitator. The spherical silver particles with average particle diameter of 100 nm were obtained under the optimum reaction conditions. The optimum synthetic conditions were found as follows: reaction temperature $100^{\circ}C$, reaction time 60 min, concentration of silver nitrate $1{\times}10^{-2}$ mol, urea $5{\times}10^{-3}$ mol, and sodium citrate $8.5{\times}10^{-4}$ mol. The phase of obtained silver particles was crystalline state and the silver particles were relatively dense, which had the surface area of $0.7571\;m^{2}/g$.

• Bulletin of the Korean Chemical Society
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• v.35 no.11
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• pp.3239-3243
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• 2014

We have developed a simple method for tuning the morphologies of $Cu_2O$ microcrystals. $Cu_2O$ microcrystals were prepared by precipitation at room temperature from a mixture of $Cu(CH_3COO)_2{\cdot}H_2O$, N,N,N',N'-tetramethyl ethylenediamine (TMEDA), ascorbic acid, and polyethylene glycol (PEG). TMEDA was used to promote the formation of copper-TMEDA complexes. A variety of $Cu_2O$ microcrystal morphologies were obtained simply by varying the concentrations of TMEDA and ascorbic acid. Aggregated $Cu_2O$ microspheres are formed at higher concentrations of ascorbic acid in the absence of TMEDA. Aggregated $Cu_2O$ microcubes are formed at lower concentrations of ascorbic acid and higher concentrations of TMEDA. The crystal growth mechanism of these $Cu_2O$ morphologies is explained.

• Journal of the Korean Chemical Society
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• v.68 no.3
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• pp.135-138
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• 2024

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.E4
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• pp.191-201
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• 2002

The pH, electric conductivity. and the major ionic components were analyzed for the precipitation samples collected at 1100 Site of Mt. Halla and Jeju city. The quality of analytical data was verified by the comparison of ion balances, conductivities and acid fractions, all of which correlation coefficients were over 0.952. The ionic strengths lower than 10$^{-4}$ M were found in 57 and 28% at 1100 Site and Jeju city respectively. The precipitation in Jeju city was influenced more by the oceanic effect than those in 1100 Site. The acidification of precipitation was caused mostly by S $O_4$$^{2-}$and N $O_3$$^{[-10]}$ in both areas, and the organic acids have contributed to the acidity with only 7~8%. The neutralization factors by N $H_3$ were about 44 and 47％ at the 1100 site and the Jeju city, respectively, whereas those by CaC $O_3$were 21 and 24%, and the free acidity were about 38 and 28％ at two sites. From the investigation of seawater and soil enrichment factors, the S $O_4$$^{2-}$, N $O_3$$^{[-10]}$ and N $E_4$$^{+}$ were immigrated by other sources rather than from the seawater or soil origins. but not in the case of $Mg^{2+}$, C $l^{[-10]}$ , N $a^{+}$, and $K^{+}$. Factor analysis has shown that the precipitation at the 1100 site had been influenced mostly by anthropogenic sources, followed by soil and sea-water sources. On the other hand, the precipitation at the Jeju city was mainly influenced by oceanic sources, followed by anthropogenic and soil sources.urces.

• Journal of the Korean Ceramic Society
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• v.56 no.5
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• pp.474-482
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• 2019

Chromium-doped zinc ferrite nanoparticles with the general formula Cr_yZnFe_2-yO₄ (y = 0, 0.025, 0.05, 0.075, and 0.1) were synthesized by a surfactant-assisted chemical co-precipitation route using metal nitrate salt precursors. The phase purity and structural parameters were determined by powder X-ray diffraction. The concentration of Cr³⁺ doped into ZnFe₂O₄ (ZF) noticeably affected the crystallite size, which was in the range of 22 nm to 36 nm, and all samples showed a single cubic spinel structure without any secondary phase or impurities. The lattice parameter, X-ray density, and skeletal density increased with an increase in the Cr-doping concentration; on the other hand, a decreasing trend was observed for the particle size and porosity. The influence of Cr³⁺ substitution on ZF magnetic properties were studied under an applied field of 15 kOe. The overall results revealed that the incorporation of a small amount of Cr dopant changed the structural, electrical, and magnetic properties of ZF.