• Journal of the Korean Applied Science and Technology
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• v.31 no.2
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• pp.176-182
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• 2014

Using alkali treatment solution, neutrality treatment solution and acid treatment solution, the surface corrosion layer of copper plates and bronze plates that have been artificially corroded using HCl, $H_2SO_4$ and $HNO_3$ solutions were removed. In the case of alkali treatment solution, only air oxidation in the form of black tenorite and white cuproous chloride remained without being removed. In the case of using a neutrality treatment solution, a anhydrous type layer of reddish brown cupric chloride remained without being removed, together with this black and white corrosion substance. In the case of using an acid treatment solution, this red corrosion substance also remained, but all of the oxide was removed on the surface of the specimen that was treated by alternatively using alkali treatment solution and acid treatment solution. In the case of this treatment solution with the order of alkali-acid, oxidation no longer proceeded only through the distilled water cleaning process after treatment, thereby showing that oxidation from the cleaning solution no longer proceeded.

• Journal of Electrochemical Science and Technology
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• v.4 no.2
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• pp.61-70
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• 2013

Corrosion inhibition of carbon steel in 2M HCl by some benzohydrazide derivatives (I-III) was studied using weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) techniques at $30^{\circ}C$. Polarization studies showed that all the investigated compounds are of mixed type inhibitors. Temperature studies revealed a decrease in efficiency with rise in temperature and corrosion activation energies increased in the presence of the hydrazide derivatives, probably implying that physical adsorption of cationic species may be responsible for the observed inhibition behavior. Electrochemical impedance studies showed that the presence of benzohydrazide derivatives decreases the double layer capacitance and increases the charge transfer resistance. The adsorption of these compounds on carbon steel surface was found to obey Temkin's adsorption isotherm. Synergistic effects increased the inhibition efficiency in the presence of halide additives namely KI and KBr. An inhibition mechanism was proposed in terms of strongly adsorption of inhibitor molecules on carbon steel surface.

• Korean Chemical Engineering Research
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• v.55 no.5
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• pp.711-717
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• 2017

A fundamental study was conducted on the dissolution of North Korean magnesite using hydrochloric acid to understand the dissolution behavior of the magnesium and impurities. The influence of the acid concentration, particle size of the magnesite, reaction temperature, and pulp density on the dissolution of magnesium, iron, calcium, aluminum, and silicon dioxide was studied. The experimental results showed that 98.5% of magnesium, 86.9% of iron, 87.3% of calcium, 23.6% of aluminum, and 20.4% of silicon dioxide were dissolved when magnesite particle sizes within the range of $75{\sim}105{\mu}m$ were reacted using 3 M HCl solution under 6% pulp density at 363 K for 3 h. The residues that remained after the dissolution were silicon dioxide, talc, and clinochlore.

• Microbiology and Biotechnology Letters
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• v.26 no.4
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• pp.365-368
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• 1998

The aklavinone 11-hydroxylase which was overexpressed using T7 promoter in E. coli could be detected in SDS-PAGE only in insoluble precipitate without any detectable enzyme activity. The insoluble enzyme was solubilized in 6M guanidine$.$HCl solution and their refolding ability was tested under various conditions. When the enzymatic activity was checked by the bioconversion experiment, stepwise dialysis against 6M, 3M, 1M guanidine$.$HCl and finally 100 mM potassium phosphate buffer of the solubilized protein gave the best bioconversion efficiency. The aklavinone 11-hydroxylase showed its enzymatic activity in the reaction buffer containing NADPH with vigorous shaking. The enzymatic activity was lost during partial purification and regained by the addition of crude extract of S. lividans in the reaction mixture. This effect was confirmed to due to some low-molecular weight component(s) in the crude extract, because the addition of dialyzed crude extract could not recover the enzymatic activity.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.2
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• pp.342-342
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• 1998

The effect of pH on the dehydration reaction of TiCl₄solution. KOH and HCl were used as a accelerater and retarder in dehydration. Results are follow. Neutralization point is pH 7.4 in the system of $TiCl_4-KOH$ and the production which is produced at acidic side is Ti-gel of poly metatitanic acid. The production which is produced at alkalic side is aligomer and crystalline potasium titanate is not detected.

• 전자공학회논문지 IE
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• v.46 no.3
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• pp.1-5
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• 2009

In this paper, we study the electrical characteristics of $RuO_2$/n-GaN Schottky diodes fabricated by using electrochemical metallization. The solution for GaN Schottky electrodes of $RuO_2$ is perchloric acid($HClO_4$). Thickness of $RuO_2$ layer depend on supplied voltage and dipping time. We verified the possibility of the rectifying and non-rectifying devices' electrode which was depend on the thickness of $RuO_2$ layer.

• Journal of Environmental Science International
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• v.5 no.6
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• pp.779-783
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• 1996

Cation exchange distribution coefficients of poly(dithiocarbamate) were presented for $Cd^{2+}$, $Cr^{3+}$, and $Pb^{2+}$ in HCI. The distribution coefficients were determined tv using the batch method. Based on these distribution data, the separation possibilities of the heavy metal ions were discussed. The distribution coefficients of three heavy metal ions on dithiocarbamate resin were decreased as HCI concentrations were increased. The selective separation of $Cr^{3+}$ and $Cd^{2+}$ was possible by using 0.1M HCl in dithiocarbamate resin and the reproducibility test showed that the average absorptivity of resin was 90% in the case of $Cd^{2+}$ ion by the column method.

• Bulletin of the Korean Chemical Society
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• v.27 no.8
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• pp.1194-1198
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• 2006

For the purpose of developing more effective chelating agents, we have synthesized a diethylene triamine pentaacetic acid(DTPA) analogue by using an amino acid. S-(N-Boc-aminophenyl)-Cys(t-Bu4-DTPA) methylester was prepared in 6 steps with total yield of 47.9%. For the sake of introducing a biomolecule to the DTPA derivative, a selective hydrolysis was performed with 3 M HCl/Ethylacetate = 1 : 3 ($25{^{\circ}C}$, 30 min, vigorous stirring). $^{166}Ho$-Cys-DTPA and $^{166}Ho$-Biotin-Cys-DTPA were prepared by mixing $^{166}Ho$ with DTPA derivatives at room temp in a HCl solution (pH = 5) and the radiochemical stabilities (> 99%) were maintained for over 6 hrs in vitro.

• Analytical Science and Technology
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• v.13 no.5
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• pp.549-557
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• 2000

FRIR-ATR spectrometry has been used to monitor the aqueous reactions of compounds without distinct chromophores in ultraviolet and visible regions. For example, hydrolysis reactions of ${\alpha}$-cyclodextrin and ${\gamma}$-cyclodextrin in acidic aqueous solution were studied. FTIR-ATR method has been used for the monitoring of cyclodextrin hydrolysis in 1.0 M. 0.5 M, and 0.1 M HCl solutions, respectively. We also found that the hydrolysis of ${\alpha}$-cyclodextrin produced glucose, but the hydrolysis of ${\gamma}$-cyclodextrin proceeded further to give more fragmented products than glucose.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.84-85
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• 2014

레늄미량함유 염산용액중에서 추출제로 Alamine304-1(Henkel), Cyanex272(Daihachi)와 $D_2EHPA(Henkel)$를 사용하여 용매추출공정으로 레늄의 추출거동을 조사하였다. 수상에 존재하는 레늄은 60 ppm이며, Kerosine과 추출제를 혼합한 합성용액을 사용하였다. 레늄 회수의 최적조건을 조사하기 위해 추출제의 종류 및 농도, 수상과 유기상의 상비, HCl의 농도, 불순물 분리 실험 등을 진행하였다. 수상의 pH가 2 이하이고, 상비는 1:1로 하여 1 % Alamine304-1으로 10분간 반응시킨 후 상온에서 1시간 이상 정치시켰을 때 레늄의 추출율이 99 % 이상으로 가장 우수하였으며, Cyanex272와 D2EHPA를 사용한 경우에는 레늄의 거의 추출되지 않았다.