• Journal of environmental and Sanitary engineering
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• v.14 no.2
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• pp.46-55
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• 1999

This study compared the adsorption characteristics of heavy metal ions by crab shell, treated crab shell with 2N-HCl, treated crab shell with 4%-NaOH, chitin and chitosan.Using crushed crab shell, the heavy metal ions removal rates of $Cd^{2+}$ and $Zn^{2+}$ were about 70-80% in 45minutes, but the removal rates of $Cu^{2+}$, $Cr^{6+}$ and $Pb^{2+}$ was less than 10%, 10% and 30%, respectively. For the by-products crab shell by 2N-HCl treatment, it was shown that the removal rates of $Cu^{2+}$ and $Pb^{2+}$ were about 70-80% in 45minutes reaction. But, some problems were observed, that the contained protein in crab shell was changed into gel in the mixing solution after a few hours. For the by-products of crab shell by 4%-NaOH treatment, the removal rates of Pb and Zn were about 90% in 45 minutes, and those of capacity of chitin and chitosan powder was better than those of the other by-products. The more adding to the adsorbent dosages increased the removal rates, and the adsorption reaction was rapidly occurred in a few minute. Using 1.0 wt% chitin powder, the heavy metal removal rates were ordered $Cu^{2+}$(94%) > $Zn^{2+}$(89%) > $Cd^{2+}$(88%) > $Pb^{2+}$(77%) > $Cr^{6+}$(58%) in 45 minutes. Using 1.0 wt% chitosan powder, the heavy metal removal rates were ordered $Cu^{2+}$(99%) > $Pb^{2+}$(96%) > $Cd^{2+}$(79%) > $Zn^{2+}$(71%) > $Cr${6+}$(46%) in 45minutes. The degree of degree of deacetylation by prepared chitosan was 91%.The Freundlich adsorption isotherm of $Cu^{2+}$, $Cd^{2+}$ and $Zn^{2+}$, when it was applied to 1.0 wt% chitosan powder in minutes, can be acceptable very strictly. The equation constant (1/n) for $Cu^{2+}$, $Cd^{2+}$ and $Zn^{2+}$ were 0.54 0.41 and 0.23 respectively.

• Journal of the Korean Chemical Society
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• v.23 no.4
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• pp.198-205
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• 1979

A valence bond method of calculation of the dipole moments for octahedral $(M(III)0_3S_3)$ type complexes are developed, using $d^2sp^3 $hybrid orbitals of the central metal ions and the single basis set orbital of ligands. (M (III) =V (III), Cr (III), Mn (III), Fe (III), Co (III), Ru (III), Rh (III) and OS (III)). In this method the mixing coefficient of the valence basis sets for the central metal ion with the appropriate ligand orbitals is not required to be the same, differently from the molecular orbital method. The valence bond method is much more easier to calculate the dipole moments for octahedral complexes than the approximate molecular orbital method and the calculated results are also in the range of the experimental vaues.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3835-3839
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• 2013

A new synthesis route for Pt nanoparticles by direct electrochemical reduction of a solid-state Pt ion precursor ($K_2PtCl_6$) is demonstrated. Solid $K_2PtCl_6$-supported polyethyleneimine (PEI) coatings on the surface of glassy carbon electrode were prepared by simple mixing of solid $K_2PtCl_6$ into a 1.0% PEI solution. The potential cycling or a constant potential in a PBS (pH 7.4) medium were applied to reduce the solid $K_2PtCl_6$ precursor. The reduction of Pt(IV) began at around -0.2 V and the reduction potential was ca. -0.4 V. A steady state current was achieved after 10 potential cycling scans, indicating that continuous formation of Pt nanoparticles by electrochemical reduction occurred for up to 10 cycles. After applying the reduction potential of -0.6 V for 300 s, Pt nanoparticles with diameters ranging from $0.02-0.5{\mu}m$ were observed, with an even distribution over the entire glassy carbon electrode surface. Characteristics of the Pt nanoparticles, including their performance in electrochemical reduction of $H_2O_2$ are examined. A distinct reduction peak observed at about -0.20 V was due to the electrocatalytic reduction of $H_2O_2$ by Pt nanoparticles. From the calibration plot, the linear range for $H_2O_2$ detection was 0.1-2.0 mM and the detection limit for $H_2O_2$ was found to be 0.05 mM.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1512-1514
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• 2001

In this work, PZT thin films were etched as a function of $Cl_2$/Ar and additive $CF_4$ into $Cl_2$(80%)/Ar(20%). The etch rates of PZT films were 1600 $\AA$/min at $Cl_2$(80%)/Ar(20%) gas mixing ratio and 1973 $\AA$/min at 30% additive $CF_4$ into $Cl_2$(80%)/Ar(20%). Therefore the etch rate of PZT in $CF_4/Cl_2/Ar$ plasma is faster than in $Cl_2$/Ar. From XPS and SIMS analysis, metal halides and C-O, FCI and $CClF_2$ were detected. The etching of PZT films in Cl-based plasma is primarily chemically assisted ion etching and the remove of nonvolatile etch byproducts is the dominant step. Consequently, we suggest that the increase of Cl radicals and the volatile oxy-compound such as $CO_y$ are made by adding $CF_4$ into $Cl_2$/Ar plasma. Therefore, the etch rate of PZT in $CF_4/Cl_2/Ar$ plasma is faster than in $Cl_2$/Ar. The etched profile of PZT films was obtained above 70$^{\circ}$ by the SEM micrograph.

• Applied Chemistry for Engineering
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• v.20 no.1
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• pp.21-27
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• 2009

Resins were synthesized by mixing 1-aza-15-crown-5 macrocyclic ligand attached to styrene (a hazardous material) divinylbenzene (DVB) copolymer with crosslink of 1％, 2％, 5％ and 20％ by a substitution reaction. The characteristic of these resins was confirmed by the content of chlorine, element analysis, thermogravimetric analysis (TGA), surface area (BET), and IR-spectroscopy. The effects of pH, time, dielectric constant of solvents and crosslink on adsorption of metal ions by the synthetic resin adsorbent were investigated. The metal ion was showed a fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in increasing order of uranium ($UO_2^{2+}$) > manganese ($Mn^{2+}$) > praseodymium ($Pr^{3+}$). The adsorption was in the order of 1％, 2％, 5％, and 20％ crosslink resin and adsorption of resin decreased in proportion to the order of dielectric constant of solvents.

• Journal of Korea Soil Environment Society
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• v.1 no.2
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• pp.51-60
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• 1996

Removal of Mn-EDTA complex and fluoride by use of hematite and ferrite, which are the by-product to be disposed of as industrial wastes, was investigated. For the comparison of removal rate, Na-bentonite known as excellent absorbent of inorganic contaminants was included in the experiments. As the results of batch mode experiments, for manganese, ferrite-A revealed 48∼65% of removal capacity, ferrite-B 46∼57%, hematite 17∼26%, while Na-bentonite showed 10∼23% of removal, depending on the initial concentration. Meanwhile, in case of fluoride : hematite revealed 53 ∼63% of removal : ferrite-A 54∼63 %, while ferrite-B did 20∼38 %. From the results, it can be postulated that the capacity of hematite and ferrite to attenuate inorganic pollutants, especially when they form complex ions, is superior to that of Na-bentonite. Consequently, the mixing of such oxide minerals with Na-bentonite will reinforce the function of Na-bentonite, especially in the undergroud liner aspect.

• Korean Journal of Materials Research
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• v.13 no.10
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• pp.635-639
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• 2003

We investigated dry etching of GaAs and AiGaAs in a high density planar inductively coupled plasma system with BCl$_3$and BCl$_3$/Ar gas chemistry. A detailed etch process study of GaAs and ALGaAs was peformed as functions of ICP source power, RIE chuck power and mixing ratio of $BCl_3$ and Ar. Chamber process pressure was fixed at 7.5 mTorr in this study. The ICP source power and RIE chuck power were varied from 0 to 500 W and from 0 to 150 W, respectively. GaAs etch rate increased with the increase of ICP source power and RIE chuck power. It was also found that etch rates of GaAs in $15BCi_3$/5Ar plasmas were relatively high with applied RIE chuck power compared to pure 20 sccm $BCl_3$plasmas. The result was the same as AlGaAs. We expect that high ion-assisted effect in $BCl_3$/Ar plasma increased etch rates of both materials. The GaAs and AlGaAs features etched at 20 sccm $BCl_3$and $15BCl_3$/5Ar with 300 W ICP source power, 100 W RIE chuck power and 7.5 mTorr showed very smooth surfaces(RMS roughness < 2 nm) and excellent sidewall. XPS study on the surfaces of processed GaAs also proved extremely clean surfaces of the materials after dry etching.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.31-36
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• 2003

We investigated dry etching of GaAs and AlGaAs in a high density planar inductively coupled plasma system with $BCl_3$ and $BCl_3/Ar$ gas chemistry. A detailed process study as a function of ICP source power, RIE chuck power and $BCl_3/Ar$ mixing ratio was performed. At this time, chamber pressure was fixed at 7.5 mTorr. The ICP source power and RIE chuck power were varied from 0 to 500 W and from 0 to 150 W, respectively. GaAs etch rate increased with the increase of ICP source power and RE chuck power. It was also found that etch rate of GaAs in $BCl_3$ gas with 25% Ar addition was superior to that of GaAs in a pure $BCl_3$ (20 sccm $BCl_3$) plasma. The result was same with AlGaAs. We expect that high ion-assisted effect in $BCl_3$/Ar plasma increased etch rates of both materials. The GaAs and AIGaAs features etched at 20 sccm $BCl_3$ and $15BCl_3/5Ar$ with 300 W ICP source power, 100 W RIE chuck power and 7.5 mTorr showed very smooth surfaces(RMS roughness < 2 nm) and excellent sidewall. XPS study on the surfaces of processed GaAs also proved extremely clean surfaces of the materials after dry etching.

• Economic and Environmental Geology
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• v.33 no.5
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• pp.405-415
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• 2000

This study was carried out to understand the formation of acid mine drainage (AMD) by pyrophyllite (so-called Napseok)-rainwater interaction (weathering), dispersion patterns of heavy metals, and patterns of mixing with non-polluted water in the Tongnae pyrophyllite mine. Based on the mass balance and reaction path modeling, using both the geochemistry of water and occurrence of the secondary minerals (weathering products), the geochemical evolution of AMD was simulated by computer code of SOLVEQ and CHILLER. It shows that the pH of stream water is from 6.2 to 7.3 upstream of the Tongnae mine. Close to the mine, the pH decreases to 2. Despite being diluted with non-polluted tributaries, the acidity of mine drainage water maintains as far as downstream. The results of modeling of water-rock interaction show that the activity of hydrogen ion increases (pH decreases), the goncentration of ${HCO_3}^-$ decreases associated with increasing $H^+$ activity, as the reaction is processing. The concentration of ${SO_4}^{2-}$first increases minutely, but later increases rapidly as pH drops below 4.3. The concentrations of cations and heavy metals are controlled by the dissolution of reactants and re-dissolution of derived species (weathering products) according to the pH. The continuous adding of reactive minerals, namely the progressively larger degrees of water-rock interaction, causes the formation of secondary minerals in the following sequence; goethite, then Mn-oxides, then boehmite, then kaolinite, then Ca-nontronite, then Mgnontronite, and finally chalcedony. The results of reaction path modeling agree well with the field data, and offer useful information on the geochemical evolution of AMD. The results of reaction path modeling on the formation of AMD offer useful information for the estimation and the appraisal of pollution caused by water-rock interaction as geological environments. And also, the ones can be used as data for the choice of appropriate remediation technique for AMD.

• Korean Journal of Acupuncture
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• v.22 no.2
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• pp.127-149
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• 2005

This study is designed to investigate the method of manufacturing herbal acupuncture through literature of oriental medicine. The findings of this study are as follows; 1. The methods of manufacturing herbal acupuncture go through the process of abstraction, purification, mixing, filtration, putting and tight sealing in the container, sterilization, quality control, printing and packing 2. There are many ways to manufacturing herbal acupuncture, for example water-alcohol precipitation, alcohol-water precipitation, liquid-liquid abstract, acid-base abstract, metal base precipitation, distillation, molecular structure, polyamide absorption, dialysis, and ion exchange, etc. And popular method is water-alcohol precipitation. This is through alcohol precipitate extracting the principal ingredients from water abstraction. This is very simple and efficient way using melting characteristics of compounds in herb to water and ethanol. 3. Sterilization of herbal acupuncture is through heating-pressure, boiling, steam flowing, low temperature, filtering, radiation, cooling, and microwaves. Nowadays filtering is commonly used. And sterilization is estimated by an examination of asepsis . 4. Herbal acupuncture must be undergo study and experiment to clinical use. The problems of herbal acupuncture are turbidity, instability, causing hemolysis, pain, and fever. So many provisions (addition, sterilization, and filtration etc.) must be prepared. 5. The theory of manufacturing herbal acupuncture is from oriental medicine, not western. So it must be corresponded to oriental medical theory, for example Gimi(氣味), Guigyung(歸經), Ingyung(引經), Bosa(補瀉), and Match of Herb. It is recommended that further study of many other sided investigations in the future.