• Journal of Environmental Health Sciences
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• v.27 no.1
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• pp.93-99
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• 2001

This study aims at finding out pertinent reaction conditions for treating high concentration ammonia contained in N-chemical factory wastewater with decompressed ammonia stripping method that was designed. And it also tries to investigate adsorption capability of removed ammonia to soil. The results from experiments are as follows ; 1. The removal rate of N $H_3$-N of synthetic wastewater was under 85% at pH 10 with decompressed ammonia stripping method. The reaction time in pressure 360 mmHg at pH 11 and 12 was shorter than in 460 mmHg, and the removal rate of N $H_3$-N with decompressed ammonia stripping method at 9$0^{\circ}C$ was 11~15% higher than air stripping 2. The optimum conditions for decompressed ammonia stripping with synthetic sample were shown as pH 12, temperature 9$0^{\circ}C$, internal reaction pressure 460 mmHg and reaction time 50 minutes. These conditions were applied to treat the wastewater containing organic-N 290.5mg/$\ell$, N $H_3$-N 168.9mg/$\ell$, N $O_2$-N 23.2mg/$\ell$, N $O_3$-N 252.4mg/$\ell$, T-N 735mg/$\ell$. Organic-N turned out to be removed 60%, the removal rate of N $H_3$-N IS 94%, T-N is 50%. But N $O_2$-N and N $O_3$-N were increased with 7.8% and 14.9% respectively. 3. The CO $D_{Sr}$ removal rate in decompressed ammonia stripping reaction was 42% and S $O_4$$^{2-}$ was removed 8.2%. It was turned out caused with higher pH and thermolysis. 4. In soil adsorption of ammonia desorbed from the decompressed stripping process of wastewater, the recovery rate was 76% in wet soil.

• Applied Chemistry for Engineering
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• v.8 no.4
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• pp.602-609
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• 1997

The seed formation and growth of $\alpha$-ferric oxyhydroxide with aerial oxidative precipitation from aqueous solution of ferrous sulfate with KOH, NaOH, $Na_2CO_3$ and $K_2CO_3$ as precipitants have been studied by free pH drift experiment. It has been shown that all precipitants give same particle formation and growth path, and average particle length from KOH and NaOH as precipitants was about 1.5 times shorter than that of $K_2CO_3$ and $Na_2CO_3$. When initial mole ratio, $R_o=[Fe^{2+}]_o/[OH^-]_o$ of KOH was decreased the particle was grown oxyhydroxide seed growth from aqueous solution of ferrous sulfate with KOH has been studied. The influence of the air flow rate, reaction temperature and initial mole ratio, $R_o=[Fe^{2+}]_o/[OH^-]_o$, on the kinetics of seed growth are investigated by static pH experiment. The oxidation rate of seed growth increased with increase in the air low rate, reaction temperature and initial mole patio. The activation energy of seed growth is 16.16 KJ/mol and the rate equation of seed growth can be written as follows: $-\frac{d[Fe^{2+}]}{dt}=1.46{\times}10^4[P_{o2}]^{0.66}[OH^-]^{2.19}exp(-\frac{16.16}{dt})$.

• Korean Journal of Materials Research
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• v.9 no.6
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• pp.556-563
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• 1999

The corrosion behavior of heat-resistant alloys, More 1 and Super 22H in molten salts of LiCl and $LiCl-Li_2$O was investigated in the temperature range of $650~850^{\circ}C$. In a molten salt of LiCl, a dense protective oxide scale of $LiCrO_2$ was formed, following growth of oxide scale with parabolic kinetics. But in a mixed molten salt of LiCl, a dense protective oxide scale of $LiCrO_2$ was formed, following growth of oxide scale with parabolic kinetics. But in a mixed molten salt of $LiCl-Li_2$O, a porous non-protective scale of Li\ulcorner(Cr, Ni, Fe)\ulcornerO$_2$was formed, following growth of oxide scale with linear kinetics. The corrosion rate increased slowly with the increase of temperature up to $750^{\circ}C$, but above $750^{\circ}C$ rapid increase in corrosion rate observed. The corrosion behavior of Super 22H alloy was similar to that of More 1 alloy, but Super 22H showed higher corrosion resistance than More 1.

• Bulletin of the Korean Chemical Society
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• v.24 no.12
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• pp.1771-1774
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• 2003

CNTs have been synthesized by catalytic $C_2H_2$ decomposition through $Pd/Al_2O_3$ at low temperature. The CNTs were grown to a length of about 10 ${\mu}$m and diameter 150-200 nm with multiwalled structure. Pd catalysts have two major roles; one is the active catalyst for $C_2H_2$ decomposition, the other is a nucleation site of CNT's growth.

• Clean Technology
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• v.24 no.1
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• pp.35-40
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• 2018

$Co_3O_4$ catalysts for $N_2O$ decomposition were prepared by co-precipitation method. Ce and Zr were added during the preparation of the catalyst as promoter with the molar ratio (Ce or Zr) / Co = 0.05. Also, 1 wt% $K_2CO_3$ was doped to the prepared catalyst with impregnation method to investigate the effect of K on the catalyst performance. The prepared catalysts were characterized with SEM, BET, XRD, XPS and $H_2-TPR$. The $Co_3O_4$ catalyst exhibited a spinel crystal phase, and the addition of the promoter increased the specific surface area and reduced the particle and crystal size. It was confirmed that the doping of K improves the catalytic activity by increasing the concentration of $Co^{2+}$ in the catalyst which is an active site for catalytic reaction. The catalytic activity tests were carried out at a GHSV of $45,000h^{-1}$ and a temperature range of $250{\sim}375^{\circ}C$. The K-impregnated $Co_3O_4$ catalyst showed much higher activity than $Co_3O_4$ catalysts with promoter only. It is found that the K-impregnation increased the concentration of $Co^{2+}$ more than the added of promoter did, and lowered the reduction temperature to a great extent.

• Analytical Science and Technology
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• v.21 no.3
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• pp.237-243
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• 2008

Nano core shell structures of $TiO_2$ particles coated on surface of ZnO nanoparticles were prepared by the polymerized complex and sol-gel method. The average particle size of ZnO by the polymerized complex method showed 100 nm and the average particle size of $TiO_2$ by the sol-gel method showed below 10 nm. The average particle size of $ZnO@TiO_2$ nano core shell struture represented about 150 nm. The agglomeration between the ZnO particles using the polymerized complex method was highly controlled by the uniform absorption of $TiO_2$ colloid on the spherical ZnO surfaces. The driving force of heterogeneous bonding between ZnO and $TiO_2$ was induced by the Coulomb force. The ZnO and $TiO_2$ particles electrified with + and - charges, respectively, resulted in strong bonding by the difference of iso-electric point (IEP) when they laid neutrality pH area, depending on the heterogeneous surface electron electrified by the different zeta potential on the pH values.

• Journal of Pharmaceutical Investigation
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• v.5 no.3
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• pp.30-35
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• 1975

When the pH of the mixture containing oxytetracycline, $MgCl_26H_2O$ (2 : 1) and citric acid in aqueous solution is changed by adding monoethanolamine, some difference substances are produced. In the range of pH 8.5-9.3, the stable substance which exhibit U. V. max. absorption at 267.5-268 nm and 372.5 nm is produced. According to preparing method, the mixture of oxytetracycline. $MgCl_26H_2O$ (2 : 1) and citric acid in 75% propylene glycol aqueous solution are dissolved with monoethanolamine, and then, it is standed for a long time. An unknown substance is precipitated. It seems to be a compound containing $MgCl_26H_2O$, citric acid and monoethanolamine, but not oxytetracycline.

• Electrical & Electronic Materials
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• v.8 no.3
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• pp.324-331
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• 1995

0.36[wt%l $SiO_{2}$ and 0.1[wt%] $H_{3}$B $O_{3}$ were added to strontium ferrite magnets of the magnetoplumbite phase SrO.5.7F $e_{2}$ $O_{3}$ to hinder grain growth and accelerate sintering, respectively. This experiment was carried out to investigate effect of particle size distribution as a function of milling time(20, 30, 40, 50, 60, 70 hours) on the magnetic properties of SrO.5.7F $e_{2}$ $O_{3}$ ferrite magnet. The B-H curve, density and the degree of orientation were measured. And the microstructure of ferrite magnets was examined with a SEM. The optimal conditions and properties of the typical sample are the following : The milling time was 60 hours. Magnetic and physical properties are $B_{r}$=4, 000[G], $_{b}$ $H_{c}$=3, 330[Oe], (BH)max=3.786[MGOe], $_{I}$ $H_{c}$=3, 525[Oe], density=5.0063[g/c $m^{3}$] and orientation factor f=0.813.0.813.3.3.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1745-1747
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• 2011

• The Korean Journal of Pharmacology
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• v.21 no.1
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• pp.62-77
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• 1985

In tile Iron-catalyzed Haber-Weiss reaction to produce OH., the requirement for $O^{-}_{2}{\cdot}$ is only to reduce $Fe^{+++}$. Possibly, the role of $O^{-}_{2}{\cdot}$ can be replaced by other reducing agents. Ascorbate is one of them in biological system. In the present study, the ability of ascorbate to produce $OH{\cdot}$ in the presence of $Fe^{++}$ and $H_2O_2$ was investigated by observing the degradation of hyaluronic acid and ethylene production from methional. Ascorbate stimulated the degradation of hyaluronic by $Fe^{++}$ and $H_2O_2$. That was confirmed by both viscosity change and gel-permeation chromatographic analysis. The observed degradation was almost completely prevented by catalase and $OH{\cdot}$ scavengers. In support of the above results, ascorbate enhanced the prouction of ethylene from methional in the presence of $Fe^{++}$ and $H_2O_2$. Other reducing agents (cysteine, glutathione, NADH and NADPH) showed similar activities to ascorbate in the degradation of hyaluronic acid and ethylene production. But no stimulatory effects were observed with their oxidized forms such as NAD and NADP. Thus, it appears that reduction of the metal ion was needed for $OH{\cdot}$ production. Among the metal ions tested, $Fe^{++}$ showed most potent catalytic action in the production of $OH{\cdot}$ The results obtained support that ascorbate can substitute $O^{-}_{2}{\cdot}$ in the metal-catalyzed reactions, particularly with $Fe^{++}$ by which $OH{\cdot}$ is produced with $H_2O_2$. The significance of the ascorbate-dependent production of $OH{\cdot}$ was considered with respect to possible role of ascorbate in the damage of inflamed joints.