• Transactions of the Korean hydrogen and new energy society
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• v.34 no.5
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• pp.478-489
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• 2023

In this study, fault diagnosis and detection methods developed to ensure the reliability of polymer electrolyte membrane (PEM) hydrogen electrolysis systems have been proposed. The proposed method consists of model development and data generation of the PEM hydrogen electrolysis system, and data-driven fault diagnosis learning model development. The developed fault diagnosis learning model describes how to detect and classify faults in the sensors and components of the system.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.2
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• pp.185-194
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• 2024

Fe-Ni nanocatalysts loaded on carbon black were prepared via spontaneous reduction reaction of iron (II) acetylacetonate and nickel (II) acetylacetonate in dry process. Their morphology and elemental analysis were characterized by scanning electron microscopy, transmission electron microscopy (TEM), and energy dispersive X-ray analyzer. The loading weight of the nanocatalysts was measured by thermogravimetric analyze and the surface area was measured by BET analysis. TEM observation showed that Fe and Ni nanoparticles was well dispersed on the carbon black and their average particle size was 4.82 nm. The loading weight of Fe-Ni nanocatalysts on the carbon black was 6.83-7.32 wt%, and the value increased with increasing iron (II) acetylacetonate content. As the Fe-Ni loading weight increased, the specific surface area decreased significantly by more than 50%, because Fe-Ni nanoparticles block the micropores of carbon black. I-V characteristics showed that water electrolysis performance increased with increasing Ni nanocatalyst content.

• Resources Recycling
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• v.33 no.2
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• pp.16-23
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• 2024

The electrolysis for extracting magnesium from seawater or brine primarily involves recovery of magnesium via precipitation as the form of magnesium hydroxide. The technology is classified into cation-exchange membranes (CEM), anion-exchange (AEM) membranes, electrodialysis, and membraneless methods. Recent research has focused on enhancing the efficiency and selectivity of magnesium recovery from seawater or brine containing magnesium, with expectations of effective magnesium recovery even with normal seawater. In a future, the optimization of the selective and efficient recovery of magnesium and various valuable substances through long-term operation of scaled-up systems is crucial with enhancing economic and environmental viability. It is essential to realistically estimate operational costs considering the membrane's lifespan and replacement cycle. Also, detailed and practical process models should be developed based on monitoring data on various factors.

• Journal of the Korean GEO-environmental Society
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• v.18 no.4
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• pp.23-29
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• 2017

As the Enforcement Ordinance of Environmental Policy Act was revised in 2013, Total Organic Carbon (TOC) was added as an indicative parameter for organic matter in Water and Aquatic Ecosystem Environmental Criteria. Under these imminent circumstances, a regulatory standard is needed to achieve the proposed TOC limitation control water quality from the STP (Sewage Treatment Plant). In this study, a electrolysis utilizing the electrochemical reaction was investigated in lab-scale experiments for the treatment of TOC in sewage effluent. TOC reduction by a electrolysis was investigated response surface methodology using the Box-Begnken methods were applied to the experimental results. A central composite design was used to investigate the effects of the independent variables of electrode space ($x_1$), current density ($x_2$) and electrolyte concentration ($x_3$) on the dependent variables removal efficiency of TOC (y). The optimal conditions for electrolysis were determined: electrode space, current density and electrolyte concentration were 50 mm, $10.3mA/cm^2$ and 0.1M, respectively. Statistical results showed the order of significance of the independent variables to be electrode space > current density > electrolyte concentration.

• Journal of the Korean Electrochemical Society
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• v.5 no.1
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• pp.7-12
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• 2002

The gas diffusion electrodes as oxygen cathodes f3r the brine electrolysis process were investigated. The gas diffusion electrode consists of a reaction layer, a gas diffusion layer, and a current distributor. The reaction layer was made from hydrophilic carbon black, hydrophobic carbon black, PTFE(polyterafluoroethylene), and Ag catalyst loaded by the silver mirror reaction or impregnation method. The gas diffusion layer was made from hydrophobic carbon black and PTFE, and Ni mesh was used as the current distributor in the reaction layer. The result that the gas diffusion electrode $(10wt\%\;Ag\;catalyst\;and\;20wt\%\;binder)$ manufactured by applying impregnation method to the carbon black f3r reaction layer showed the better performance was obtained from experiments. From the half-cell test, the measured overpotential of this oxygen cathode was about 700mV, And through the electrolysis experiment under the condition of $80^{\circ}C,\;32wt\%$ NaOH, and $300mA/cm^2$, the electrolysis voltage of this electrode was about 2.2 V, The gas diffusion electrodes manufactured in the present research were capable of continuous operations for three months.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.1
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• pp.1-7
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• 2016

In order to treat electrolysis nickel plating pickling wastewater to meet the effluent limit less than 3.0 mg/L, the electrolysis process by using soluble and insoluble electrode were studied. Electrolysis using soluble electrodes has a characteristic of easy elution from the electrode which the insoluble electrodes close not release metal from the electrode. For these reasons, there exist different characteristics in nickel removal efficiency, purity of nickel sludge. With this connection, the feasibility test were concluded to develop optimal conditions for the treatment of pickling wastewater electrolysis by using soluble electrodes, insoluble electrodes. Optimal condition of current density, pH were derived from the pickling wastewater using insoluble electrodes. It was concluded the highest removal efficiency of nickel at the operation condition of at pH 9, current density of $15mA/cm^2$. At these conditions, 95.3% purity of nickel sludge was achieved, iron content was 2.9%. Optimal condition when using soluble electrodes was derived current density of $10mA/cm^2$, pH 9. Purity of nickel sludge was 77.3%, iron content was 21.0%. 50.7% and 24.2% of operating cost can be saved by the use of soluble electrodes and the use of insoluble electrodes, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.979-984
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• 2011

Although sludge production has been increased due to the number of the wastewater treatment plants expanded, needs of the techniques for the sludge reduction and disposal has been issued importantly because the sludge dumping to ocean is prohibited from 2012 by the London Dumping Convention. Therefore, the sludge solubilization using electrolysis as an alternative techniques for the sludge disposal was carried out in this study. Iridium coated titanium based insoluble electrodes were used and 20 volt was applied to the electrolysis reactor using DC power supply. Supernatants of the treated sludge was monitored: The soluble COD, TN, TP of it was increased to 151%, 22% and 6% respectively. And the sludge floc size distribution was changed, that is, the flocs ranged from 0.1 to 1.0 ${\mu}m$ were increased. All of these results indicate that the cells were lysed and the internal matters bursted out of the cell after electrolysis. As well as the reduction of the sludge production, the soluble organic matters from the cells could be used as an external carbon sources in the advanced wastewater treatment plants.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.6
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• pp.329-333
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• 2016

Disinfection by electrolysis would be useful for small wastewater treatment plant, combined sewer overflow, ballast water, swimming pool, and fish farming, where the transport, storage, and the use of chlorine gas is limited. This study investigated the feasibility of the electrolysis of dilute hydrochloric acid (HCl) for disinfection. The effects of HCl concentration, voltage and reaction time on the generation of oxidizing agents, HOCl, $O_3$, and $H_2O_2$, were examined in a series of batch test. The highest current efficiency was 99.3% which was found at 2.2%, 3 V, and 5 min of HCl concentration, voltage, and reaction time, respectively. Continuous electrolysis at 2.2% HCl, 3 V, and 5 min of the hydraulic retention time showed 97.4% of the current efficiency. Addition of sodium chloride up to 20 g/L linearly increased the oxidizing agents production. 92.2% of total coliforms were removed by the contact with the electrolyzed water.

• Economic and Environmental Geology
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• v.47 no.6
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• pp.645-655
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• 2014

In order to obtain pure metallic Te from gold concentrate, roasting treatment, hypochlorite leaching, Fe removal and electrolysis experiments were carried out. The contents of Au, Ag and Te from the concentrate sample and roasted sample were much more soluble in the hypochlorite solution than in aqua regia digestion, whereas the metals Pb, Zn, Fe and Cu were easier to leach with the aqua regia than the hypochlorite. With the addition of NaOH in the hypochlorite leaching solution prior to electrolysis, the Fe removal rate achieved was only 96% in the concentrate sample, while it reached 98% in the roasted sample. The results of electrolysis for 240 min, 98% of the metallic copper was recovered from the concentrate sample, while 99% was obtained from the roasted sample due to the removal of S by roasting. The amount of anode slime was also greater in the electrolytic solution with the roasted sample than with the concentrate sample. The results on the anode slime after the magnetic separation process showed the amount of metallic pure native tellurium recovered was greater in the roasted sample than in the concentrate sample.

• Applied Chemistry for Engineering
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• v.32 no.3
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• pp.332-339
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• 2021

Recently, due to concerns about the depletion of fossil fuels and the emission of greenhouse gases, the importance of hydrogen energy technology, which is a clean energy source that does not emit greenhouse gases, is being emphasized. Water electrolysis technology is a green hydrogen technology that obtains hydrogen by electrolyzing water and is attracting attention as one of the ultimate clean future energy resources. In this study, the surface properties of the porous transport layer (PTL), one of the cell components of the proton exchange membrane water electrolysis (PEMWE), were controlled using a sandpaper to reduce overvoltage and increase performance and stability. The surfaces of PTL were sanded using sandpapers of 400, 180, and 100 grit, and then all samples were finally treated with the sandpaper of 1000 grit. The prepared PTL was analyzed for the degree of hydrophilicity by measuring the water contact angle, and the surface shape was observed through SEM analysis. In order to analyze the electrochemical characteristics, I-V performance curves and impedance measurements were conducted.