• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.161-171
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• 1997

Anodic regeneration of PCB enchant and cathodic deposition of copper using electrochemical method has been studied. Cu(I)/Cu(II) concentration ratio as a function of Cu(I) oxidation at the anode was measured from the potential difference between platinum and Ag/AgCl/4M KCl electrodes. Chlorine gas evolution was minimized by maintaining Cu(I) concentration above a specific concentration and using non-porous graphite electrode. Dendritic copper deposition was observed at the cathode and the optimum conditions for Cu deposition was identified as the current density of $360mA/cm^2$, and copper concentration of 12 g/l. Titanium was the most effective cathode material which showed a higher current efficiency and copper recovery. The current efficiency decreased with increasing temperature, but the highest power efficiency was achieved at $50^{\circ}C$.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.4
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• pp.349-355
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• 2018

This study interrogated multi-layer heterojunction anodes were interrogated for potential applications to water treatment. The multi-layer anodes with outer layers of $SnO_2/Bi_2O_3$ and/or $TiO_2/Bi_2O_3$ onto $IrO_2/Ta_2O_5$ electrodes were prepared by thermal decomposition and characterized in terms of reactive chlorine species (RCS) generation in 50 mM NaCl solutions. The $IrO_2/Ta_2O_5$ layer on Ti substrate (Anode 1) primarily served as an electron shuttle. The current efficiency (CE) and energy efficiency (EE) for RCS generation were significantly enhanced by the further coating of $SnO_2/Bi_2O_3$ (Anode 2) and $TiO_2/Bi_2O_3$ (Anode 3) layers onto the Anode 1, despite moderate losses in electrical conductivity and active surface area. The CE of the Anode 3 was found to show the highest RCS generation rate, whereas the multi-junction architecture (Anode 4, sequential coating of $IrO_2/Ta_2O_5$, $SnO_2/Bi_2O_3$, and $TiO_2/Bi_2O_3$) showed marginal improvement. The microscopic observations indicated that the outer $TiO_2/Bi_2O_3$ could form a crack-free layer by an incorporation of anatase $TiO_2$ particles, potentially increasing the service life of the anode. The results of this study are expected to broaden the usage of dimensionally stable anodes in water treatment with an enhanced RCS generation and lifetime.

• Journal of the Korean Chemical Society
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• v.50 no.4
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• pp.328-337
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• 2006

purpose of this study was to find out problems in experiments for electrolysis of an aqueous CuCl2 solution in high school science textbooks and to suggest an improved experiment considering students' capability of experimenting and laboratory safety in high schools. For this study, the experiments for electrolysis of an aqueous CuCl2 solution presented in 11 high school science textbooks were classified by their experimental methods. After high school chemistry teachers performed the experiments as presented in the high school science textbooks, an analysis was performed on problems of the experiments, and an improved experiment was devised. According to the results of this study, in the experiments for electrolysis of an aqueous CuCl2 solution using a U type tube and a U type tube with branch, reaction velocity of the electrolysis was slow, therefore, a side reaction was generated. In the experiment using a beaker, reaction of each electrode could not be observed separately. And in the experiment using an electrolysis instrument, it was difficult to identify property of the reaction product. In the improved experiment using a reaction vessel of ㅂshape, reaction velocity of the electrolysis was fast, reaction of each electrode could be observed separately, and the side reaction decreased. From these results, it was suggested that the improved experiment would help high school students understand scientific conception regarding electrolysis.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.41 no.6
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• pp.37-42
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• 2004

It is necessary for what just keep a living body balance be devoted to it being varied with acidity serious trouble, and constitution of a study person about the density (ph) change that an alkaline ion necessary for a living body is numerical to supply a human body with number alkali by PWM voltage control. Works in the water which included the calcium (Ca), kalium (K), magnesium (Mg), natrium (Na) back who is helpful for a human body, and there is Alkaline. It is done this alkaline electrolysis to ask in order to create a number, and minerals are gathered through isolated layer (isolated special layer) to a - electrode direction, and is created. of course, prominent derelicts gather, and the acidity capital is happened, and -ion of a chlorine (Cl), phosphorus(P), sulfur (S) back is usable unfavorably in water of different use to a + electrode direction. Microprocessor was used with a - pole and a + pole with a PWM(pulse width modulation) voltage in this electrolysis process, and four kinds of PWM voltages were implemented, and a voltage every ph density change tried to be considered. It is expected by getting exactly if number alkaline ion of ph density value necessary is done with setting value if PWM control is used thus.

• Clean Technology
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• v.27 no.2
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• pp.152-159
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• 2021

Volatile organic compounds (VOCs) occur in indoor and outdoor industrial and urban areas and cause environmental problems. Malodorous VOCs, along with aesthetic discomfort, can have a serious effect on the human body. Compared with the existing method of reducing malodorous VOCs, a wet scrubbing method using an electrolytic oxidant has the advantage of reducing pollutants and regenerating oxidants. This study investigated the optimal conditions for producing OCl^-, a chlorine-oxidant. Experiments were conducted by changing the type of anode and cathode electrode, the type of electrolyte, the concentration of electrolytes, and the current density. With Ti/IrO₂ as the anode electrode and Ti as the cathode electrode, OClproduction was highest and most stable. Although OCl^- production was similar with the use of KCl or NaCl, NaCl is preferable because it is cheap and easy to obtain. The effect of NaCl concentration and current density was examined, and the OCl^- production rate and concentration were highest at 0.75 M NaCl and 0.03 A cm^-2. However, considering the cost of electric power, OCl^- production under the conditions of 1.00 M NaCl and 0.01 A cm^-2 was most effective among the conditions examined. It is desirable to produce OCl^- by adjusting the current density in accordance with the concentration and characteristics of pollutants.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.10
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• pp.709-716
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• 2011

Effect of inorganic coagulants dosing on the performance of electro-chemical process was studied when treating hospital wastewater having low electrolyte concentration. It is thought that adding inorganic coagulants caused increase in concentration of electrolyte and this caused increase in free chloride concentration and consequently, caused increase in indirect oxidation effect. Thus, COD removal efficiencies more than doubled in percentage terms at the 2 hrs of reaction time and current density of $1.76A/dm^2$ compared with the results obtained from the parallel experiments without adding inorganic coagulants. T-N removal efficiencies approximately doubled in percentage terms at the 2 hrs of reaction time and 700 ppm of coagulants addition and applied current density of $1.76A/dm^2$ due to the increase of free residual chlorine such as HOCl caused by increase of electrolyte concentration through the addition of inorganic coagulants. Under the same experimental condition, more than 90% of T-P removal efficiencies was obtained. The reason can be explained that increase of chemical adsorption rate between phosphate and insoluble metal compounds caused by dissolved oxygen generated from anode by the increased electrolyte concentration through inorganic coagulants addition make a major role in improving T-P removal efficiencies. It can be concluded that inorganic coagulants addition as the supplemental agent of electrolyte is effective way in improving organic and nutrient salt removal efficiency when treating hospital wastewater having low electrolyte concentration.

• Journal of the Korean institute of surface engineering
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• v.51 no.4
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• pp.207-213
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• 2018

Not only efficiency of chlorine evolution reaction (CER) but also durability namely service life is very important property in dimensional stable anode for Ballast Water Management System (BWMS) for marine ships. Many researchers have been focused on improving efficiency of CER by controlling composition, phase and surface area for a long time, but the efforts to increase durability was relatively small. In this study, we have investigated the effect of $TiO_2$ protective interlayers on efficiency and durability of DSA electrodes. $TiO_2$ protective interlayers were prepared by thermal oxidation at 500, 600 and $700^{\circ}C$ on Ti substrate. And then the DSA electrodes consisting of $Ti/RuO_2-PdO-TiO_2$ were prepared by thermal decomposition method on $TiO_2$ interlayers. The efficiencies of CER of DSA electrodes without $TiO_2$ interlayer and with $TiO_2$ interlayer grown at 500, 600 and $700^{\circ}C$ were 94.19, 94.45, 84.60 and 76.75% respectively. On the otherhand, durabilities were 30, 55, 90 and 65 hours respectively. In terms of industrial aspect, the performance of DSA is considered high efficiency and durability which can correspond to total production of chlorine. If we considered the performance index of DSA as the product of efficiency and durability, performance indices could be recalculated as 28.26, 50.85, 76.14 and 49.89 respectively. As the thermal oxidation temperature increasing, life time were increased remarkerbly, while efficiency of CER was decreased slightly. As a result, DSA electrode with $TiO_2$ interlayer grown at $600^{\circ}C$ has shown about 2.7 times performace of original DSA electrode without $TiO_2$ interlayer.

• Applied Chemistry for Engineering
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• v.20 no.3
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• pp.296-300
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• 2009

Generation of chlorine dioxide ($ClO_2$) was studied by the un-divided electrochemical cell system using $RuO_2$ anode material. Sodium chlorite ($NaClO_2$) was used as a precursor compound of chlorine dioxide. Effect of various operating parameters such as feed solution flow rate, initial solution pH, $NaClO_2$ and NaCl conc., and applied current density on the produced chlorine dioxide concentration and solution pH were investigated in un-divided electrochemical cell system. Produced chlorine dioxide concentration and solution pH were strongly depends on the initial solution pH and feed solution flow rate. Sodium chloride (NaCl) was not only good electrolyte, it was also used as a raw material of chlorine dioxide with $NaClO_2$. Observed optimum conditions were flow rate of feed solution (90 mL/min), initial pH (2.3), $NaClO_2$ concentration (4.7 mM), NaCl concentration (100 mM), and current density ($5A/dm^2$). Produced chlorine dioxide concentration was around 350 mg/L and solution pH was around 3.