• Journal of Advanced Marine Engineering and Technology
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• v.41 no.3
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• pp.276-280
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• 2017

In this study, we investigated the effect of sterilization and the neutralization of treated ballast water using seawater electrolysis. The electrolysis apparatus has a cation-selective membrane for passing the cation and a titanium electrode in each cell. We examined the sterilization effect after an incubation period of 24 hr. The oxidation reaction during electrolysis caused, the solution to become strongly acidic due to the generation of a hydroxyl group, and the oxidation reduction potentials(ORP) was increased to 800 - 1200mV. After the reduction reaction, the solution became alkaline(pH 9 - 12), and ORP was decreased to - 900 - - 750 mV. It might be possible to control the pH of ballast water through electrolysis. In addition, we demonstrated the effects of sterilization of ballast water containing generated hypochlorous acid using electrolysis under high ORP condition.

• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.295-304
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• 1994

$Mo-V-O/SnO_2$(VM/Sn) and $SnO_2/Mo-V-O$(Sn/VM) catalysts have been prepared and characterized by XRD, BET, SEM and TPD of ammonia. The catalytic reaction of acrolein oxidation with these catalysts, in a continuous-flow fixed-bed reactor, showed that they had higher conversion of acrolein and higher yield of acrylic acid than those of Mo-V-O itself. The origin of the observed synergy studied by TPD, TPR and TPO is explained by the cooperation of $SnO_2$ and Mo-V-O at their interfaces where electrons flow from Mo-V-O phase to $SnO_2$ and $SnO_2$ produces spill-over oxygens, which, by being transported onto the surface of Mo-V-O, reoxidize the partially reduced active sites.

• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.64-72
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• 2017

A series of Pt-based ${\gamma}-Al_2O_3$ catalysts promoted with several alkali and alkaline earth metals were prepared by a wet impregnation method. We confirmed that the addition of Na to $Pt/{\gamma}-Al_2O_3$ could cause a change in the oxidation state of Pt through an electronegative gap between Pt and Na atom, and increase the ratio of the metallic Pt. The metallic Pt species made by adding an optimum Na content improved the adsorption of NO species on the catalyst surface and restrained the oxidation of $CH_4$ to $CO_2$. When molar ratio of Na/Pt was 4.0, the highest catalytic activity could be obtained.

• Resources Recycling
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• v.26 no.3
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• pp.26-31
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• 2017

LIX 63 showed a selectivity for the extraction of Pd(II) over other PGMs, such as Pt(IV), Ir(IV) and Rh(III) from 6 M HCl solution. Moreover, HCl solution has significant effect on the oxidation-reduction reaction between Ir(IV) and LIX 63. Therefore, the applicability of employing LIX 63 for the separation of the 4 PGMs was investigated from 3 M HCl solution. From 3 M HCl solution, only Pd(II) was selectively extracted by LIX 63 and its extraction percentage was higher than from 6 M HCl solution. Extraction of the Pd(II) free raffinate with TBP led to the selective extraction of Pt(IV). After oxidation of Ir(III) with $NaClO_3$ to Ir(IV), extraction of the Pt(IV) free raffinate with Aliquat 336 selectively extracted Ir(IV). For each extraction step, optimum stripping conditions were obtained. By this process, it was possible to separate the 4 PGMs by solvent extraction from 3 M HCl solution.

• Corrosion Science and Technology
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• v.9 no.6
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• pp.259-264
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• 2010

In continuous hot dip galvanizing process, oxide formation on steel surface has an influence on Zn wetting. High strength automotive steel contains high amount of Si and Mn, where Si-Mn composite oxides such as $Mn_2SiO_4$ or $MnSiO_3$ covers the surface after annealing. Zn wetting depends on how the aluminothermia reaction can reduce the Mn-Si composite oxides and then form inhibition layer such as $Fe_2Al_5$ on the steel surface. The outward diffusion of metallic ions such as $Mn^{2+}$, $Si^{2+}$ in the steel matrix is very important factor for the formation of the surface oxides on the steel surface. The surface state and grain boundaries provide an important role for the diffusion and the surface oxide reactions. Some elements such as P, Sb, and B have a strong affinity for the interface precipitation, and it influence the diffusivity of metallic ions on grain boundaries. B oxide forms very rapildly on the steel surface during the annealing, and this promote complex oxides with $SiO_2$ or MnO. P has inter-reacted with other elements on the grain boundaries and influence the diffusion through on them. Small addition of Sb could suppress the decarburization from steel surface and retards the formation of internal and external selective oxides on the steel surface. Interface control by the trace elements such as Sb could be available to improve the Zn wettability during the hot dip galvanizing.

• Applied Science and Convergence Technology
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• v.26 no.6
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• pp.218-222
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• 2017

This study was conducted to remove $NO_x$, which is the main cause of fine dust and air pollution as well as acid rain. $NO_x$ was tested using 3% NO (diluted in He) as a simulated gas. Experiments were sequentially carried out by oxidizing NO to $NO_2$ and absorbing $NO_2$. Especially, we focused on the changes of NO oxidation according to both oxidant ($NaClO_2$) concentration change (1~10 M) and oxidant pH change (pH = 1~5) by adding HCl. In addition, we tried to suggest a method to improve $NO_2$ absorption by conducting $NO_2$ reduction reaction with reducing agent (NaOH) concentration (40~60%). It was found that NO removal efficiency increased as both concentration of oxidant and flow rate of NO gas increased, and NO decreased more effectively as the pH of hydrochloric acid added to the oxidant was lower. The $NO_2$ adsorption was also better with increasing NaOH concentration, but the NO removal efficiency was ~20% lower than that of the selective NO reduction. Indeed, this experimental method is expected to be a new method that can be applied to the capture and removal of fine dust caused by air pollution because it is a method that can easily remove NO gas by a simple device without expensive giant equipment.

• Journal of Powder Materials
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• v.26 no.4
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• pp.290-298
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• 2019

$TiO_2$-particles containing Co grains are fabricated via thermal hydrogenation and selective oxidation of TiCo alloy. For comparison, $TiO_2$-Co composite powders are prepared by two kinds of methods which were the mechanical carbonization and oxidation process, and the conventional mixing process. The microstructural characteristics of the prepared composites are analyzed by X-ray diffraction, field-emission scattering electron microscopy, and transmission electron microscopy. In addition, the composite powders are sintered at $800^{\circ}C$ by spark plasma sintering. The flexural strength and fracture toughness of the sintered samples prepared by thermal hydrogenation and mechanical carbonization are found to be higher than those of the samples prepared by the conventional mixing process. Moreover, the microstructures of sintered samples prepared by thermal hydrogenation and mechanical carbonization processes are found to be similar. The difference in the mechanical properties of sintered samples prepared by thermal hydrogenation and mechanical carbonization processes is attributed to the different sizes of metallic Co particles in the samples.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.378-384
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• 2018

$C_9H_7NHCrO_3Cl$ was synthesized by reacting $C_9H_7NH$ with chromium (VI) trioxide. The structure of the product was characterized by FT-IR (Fourier transform infrared) spectroscopy and elemental analysis. The oxidation of benzyl alcohol by $C_9H_7NHCrO_3Cl$ in various solvents showed that the reactivity increased with increasing dielectric constant(${\varepsilon}$) in the following order: DMF (N,N'-dimethylformamide) > acetone > chloroform > cyclohexane. The oxidation of alcohols was examined by $C_9H_7NHCrO_3Cl$ in DMF. As a result, $C_9H_7NHCrO_3Cl$ was found to be an efficient oxidizing agent that converts benzyl alcohol, allyl alcohol, primary alcohols, and secondary alcohols to the corresponding aldehydes or ketones (75%-95%). The selective oxidation of alcohols was also examined by $C_9H_7NHCrO_3Cl$ in DMF. $C_9H_7NHCrO_3Cl$ was the selective oxidizing agent of benzyl, allyl and primary alcohol in the presence of secondary ones. In the presence of DMF with an acidic catalyst, such as $H_2SO_4$, $C_9H_7NHCrO_3Cl$ oxidized benzyl alcohol (H) and its derivatives ($p-OCH_3$, $m-CH_3$, $m-OCH_3$, m-Cl, and $m-NO_2$). Electron donating substituents accelerated the reaction rate, whereas electron acceptor groups retarded the reaction rate. The Hammett reaction constant (${\rho}$) was -0.69 (308K). The observed experimental data were used to rationalize hydride ion transfer in the rate-determining step.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.927-933
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• 2022

We synthesized (C₁₀H₈N₂H)₂Cr₂O₇, The structure of the product was characterized with FT-IR(infrared) and elemental analysis. The oxidation of benzyl alcohol by (C₁₀H₈N₂H)₂Cr₂O₇ in organic solvents showed that the reactivity increased with the increase of the dielectric constant. The oxidation of alcohols was examined by (C₁₀H₈N₂H)₂Cr₂O₇ in DMF, acetone. As a resuit, (C₁₀H₈N₂H)₂Cr₂O₇ was found as efficicent oxidizing agent that converted benzyl alcohol, allyl alcohol, primary alcohol and secondary alcohols to the corresponding aldehydes or ketones(65%~95%). The selective oxidation of alcohols was also examined by (C₁₀H₈N₂H)₂Cr₂O₇ in DMF, acetone. (C₁₀H₈N₂H)₂Cr₂O₇ was selective oxidizing agent(15%~95%) of benzyl alcohol, allyl alcohol and primary alcohol in the presence of secondary ones. In the presence of DMF solvent with acidic catalyst such as H₂SO₄. (C₁₀H₈N₂H)₂Cr₂O₇ oxidized benzyl alcohol(H) and its derivatives. The Hammett reaction constant(ρ) was -0.69(308K). The observed experimental data were used to rationalize the hydride ion transfer in the rate determining step.

• Journal of the Mineralogical Society of Korea
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• v.27 no.2
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• pp.73-83
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• 2014

In order to investigate selective phase transformations and to determine the maximum Au leaching factors from microwave treated Au-bearing complex sulfides, a microscope, SEM-EDS analysis, and thiocyanate leaching tests were performed. When the Au-bearing complex sulfides were exposed to microwave heating, increasing the microwave exposure time increased temperature and decreased weight. Arsenopyrite was first selectively transformed to hematite, which formed a concentric rim structure. In this hematite, oxygen and carbon was detected and always showed high iron content and low arsenic content due to arcing and oxidation from microwave heating. The results of the leaching test using microwave treated sample showed that the maximum Au leaching parameters was reached with 0.5 g concentration thiocyanate, 2.0 M hydrochloric acid, 0.3 M copper sulfate and leaching temperature at$60^{\circ}C$. Under the maximum Au leaching conditions, 59% to 96.69% of Au was leached from the microwave treated samples, whereas only 24.53% to 92% of the Au was leached from the untreated samples.