• Membrane Journal
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• v.31 no.6
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• pp.443-455
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• 2021

In this study, polyphenylene sulfide (PPS) was used as a support and a separator was manufactured using polysulfone and inorganic additives to manufacture a separator with low membrane resistance for application of an alkali water electrolysis system, and then the effect on the thickness and porosity of the support was analyzed. The PPS felt used as a support was compressed with variables of temperature (100℃, 150℃, 200℃) and pressure (1 ton, 2 tons, 3 tons, 5 tons) to adjust the thickness. A porous separator could be manufactured by preparing a slurry with polysulfone using BaTiO₃ and ZrO₂ which have high hydrophilicity and excellent alkali resistance as inorganic particles and casting the slurry on a compressed PPS felt. Changes in morphology of the separator according to compression conditions were confirmed through an electron scanning microscope (SEM). After that, the porosity was calculated, and the thickness and porosity tended to decrease as the compression conditions increased. Various characteristics were evaluated to confirm whether it could be used as a separator for water electrolysis. As a result of measuring the mechanical strength, it was confirmed that the tensile strength gradually increased as the compression conditions (temperature and pressure) increased. Finally, it was confirmed that the porous separator manufactured through the alkali resistance test has excellent alkali resistance, and through the IV test, it was confirmed that the membranes compressed at 100℃ and 150℃ had a lower voltage and improved performance than the existing uncompressed membrane.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.5
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• pp.433-439
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• 2017

The high temperature performance of PEM type electrolyser at $120^{\circ}C$ based on covalently cross-linked sulfonated poly ether ether ketone (SPEEK) composie membrane was investigated. Ion conductivity and other properties of SPEEK membrane were improved by adding heteropoly acid and Ceria. The membrane electrode assemblies were prepared using commercial PtC and nano-sized $IrRuO_2$ catalyst by electro-spraying and decal process. Voltage efficiency of MEA equipped with SPEEK membrane was slightly better than that of $Nafion^{(R)}$ membrane, due to its higher proton conductivity at high temperature. The cell performance of MEA with CL-SPEEK/Cs-TSiA/Ceria is 1.71 V at $1A/cm^2$ and $120^{\circ}C$.

• Clean Technology
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• v.14 no.3
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• pp.218-223
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• 2008

Decomposition of reactive organic compound dispersed in microemulsion media by hydroxide ions and proton ions generated during electrolysis was tried and the half-lifes for decomposition were compared. Absorbance of p-nitrophenoxide produced from the decomposition of p-nitrophenylacetate (PNPA) was followed to find the rate of decomposition. The applied voltage, temperature, and the amount of substrate were changed to see the effects on the decomposition rate. The advantages of electrolysis in microemulsion system were the high solubilizing capacity of substrate, easy control of decomposition rate, low operation cost, no need for any addition of chemicals, and no byproducts. The mechanism of decomposition and the application to water purification were discussed.

• The KSFM Journal of Fluid Machinery
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• v.20 no.2
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• pp.69-74
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• 2017

Sodium hypochlorite, used as water disinfectant, is generated by electrolysis of salt. Compared to chlorine gas disinfection, it is free from high-pressure gas regulation and does not generate toxic gas, so it is increasingly used as a safe disinfectant. Despite these advantages, the concentration of sodium hypochlorite decreases with temperature during long-term storage, and the amount of chlorate increases when a large amount is added, it has mainly been applied to small-scale waterworks. To solve this problem, high sodium hypochlorite generation was developed. In this study, the changes of concentration and chlorate of sodium hypochlorite with time has been studied. As a result of the test, it was found that the usable period of sodium hypochlorite produced at a certain temperature or less was increased from 1.5 days to 13 days. Overall, sodium hypochlorite can be applied even in large-scale waterworks, which makes operation more stable and also reduces the disinfection byproducts, thus it contributed greatly to securing water quality.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.1
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• pp.40-48
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• 2005

Until recently, only perfluorinated ionomer membrane such as Nation and Aciflex practically could be successfully used in water splitting. However, these membrane are limited by high cost and loss of membrane performance such as proton conductivity at elevated temperature above 80$^{\circ}C$. The sulfonated aromatic polymers such as PEEK and PSf, polyimides, and polybenzimidazoles are expected to have lower production cost as well as satisfactory chemical and electrochemical properties. HPAs and sulfonated polymers could have a significant influence on water electrolysis performance at elevated temperatures above 80$^{\circ}C$, but these phenomena have received relatively little attention until now. Therefore, it would be desirable to investigate the interrelation between the HPA and sulfonated polymer, such as SPEEK. The SPEEK membrane were prepared by the sulfonation of PEEK, and HPA was blended with SPEEK to increase the mechanical strength and electrochemical characteristics. As a results, electrochemical characteristics such as proton conductivity and ion exchange capacity were improved with the addion of 0.5 g HPA. And the properties of polymer electrolyte, SPEEK/HPA were better than Nation membrane at elevated temperature above 80$^{\circ}C$.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.5 no.1
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• pp.1-8
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• 2009

Nuclear hydrogen production using high temperature heat of a very high temperature reactor(VHTR) is one of the most attractive ways of mass hydrogen production without greenhouse gas emission. In many countries, sulfur-iodine(S-I) thermochemical process and high temperature steam electrolysis(HTSE) process are being investigated. In such processes, corrosion behavior of Intermediate heat exchanger materials are the most critical issues. Especially in a HTSE system, several heat exchangers will be facing hot steam conditions. In this paper, the status of high temperature corrosion researches in hot steam and supercritical water conditions are reviewed in view of the implication to HTSE conditions. Based on the review, test condition and plan of the hot steam corrosion of the candidate materials are formulated and described in some details along with the schematics of the test set-up. The test results and subsequent evaluation will be used in development of a interface system between the HTSE hydrogen production system and the VHTR.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.228.2-228.2
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• 2010

In this work, the hydrogen production costs of the nuclear energy sources are estimated in the necessary input data on a Korean specific basis. G4-ECONS was appropriately modified to calculate the cost for hydrogen production of HTE process with Very High Temperature nuclear Reactor (VHTR) as a thermal energy source rather than the LUEC (Levelized Unit Electricity Cost). The general ground rules and assumptions follow G4-ECONS. Through a preliminary study of cost estimates, we wished to evaluate the economic potential for hydrogen produced from nuclear energy, and, in addition, to promptly estimate the hydrogen production costs for an updated input data for capital costs. The estimated costs presented in this paper show that hydrogen production by the VHTR could be competitive with current techniques of hydrogen production from fossil fuels if $CO_2$ capture and sequestration is required. Nuclear production of hydrogen would allow large-scale production of hydrogen at economic prices while avoiding the release of $CO_2$. Nuclear production of hydrogen could thus become the enabling technology for the hydrogen economy. The major factors that would affect the cost of hydrogen were also discussed.

• Journal of the Korean institute of surface engineering
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• v.49 no.2
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• pp.125-129
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• 2016

Anodizing is a technology to generate thicker and high-quality films than natural oxide films by treating metals via electrochemical methods. Electrochemical manufacturing method of nano structure is an efficient technology in terms of cost reduction, high productivity and complicated shapes, which receives the spotlight in diverse areas. Especially, artificial films generated by anodizing technology possess excellent mechanical characteristics including hardness and wear resistance. It is also easy to modify thickness and adjust shape of those artificial films so that they are mainly used in sensors, filters, optical films and electrolytic condensers. In this study, experiment was performed to observe the effect of current density on porous film formation in two-step anodizing for Al alloy. Anodizing process was performed with 10 vol.% sulfuric acid electrolyte while the temperature was maintained at $10^{\circ}C$ using a double beaker. and $10{\sim}30mA/cm^2$ was applied for 40 minutes using a galvanostatic method. As a result, both pore diameters and distances between pores tended to increase as the local temperature and electrolysis activity increased due to the increase in applied current density.

• Journal of the Korean Chemical Society
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• v.50 no.6
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• pp.454-463
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• 2006

refractory organic compounds in aqueous solution are not readily removed by the existing conventional wastewater treatment process. In recent years, the sonolysis and electrochemical oxidation process had been shown to be promising for wastewater treatment due to the effectiveness and easiness in operation. This study was performed to investigate the characteristics of sonolytic and electrolytic decomposition as the basic data for development of the wastewater treatment process. Trichloroethylene(TCE) and 2,4- dichlorophenol(2,4-DCP) were used as the samples, and their destruction efficiency were measured with various operating parameters, such as initial solution concentration, initial solution pH, reaction temperature, sonic power and current density. Also, the decomposition mechanism conformed indirectly with the effect of NaHCO3 as a radical scavenger on the decomposition reaction. Thermal decompositon reaction is predominant for TCE but thermal and radical decompositon reactions were dominant for 2,4-DCP. Results showed that the destruction efficiencies of all samples were above 65% within 120 minutes by sonolysis and electrolysis at the same time, and were increased with increasing initial concentration, sonic power and current density. Destruction efficiency of TCE was high in the acidic solution, but 2,4-DCP showed high destruction efficiency in basic solution.

• Journal of the Korean institute of surface engineering
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• v.18 no.3
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• pp.95-104
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• 1985

A study has been made of preferred orientation, crose sectional microstructure, surface morphology and mechanical properties of copper foils fabricated by electrodeposition on 304 stainless steel plate from copper sulfate baths for high speed plating. The preferred orientation of the copper foils changed from the [110] to the [111] to ture with decreasing bath temperature and increasing cathode current density. The foils with the [110] texture had the field oriented texture type structure and the surface of many asperities grooved approximately perpendicular to the subtrate. A specimen with the [111]+[311] texture had the lower strength than one with the [10] texture, if they were obtained under similar electrolysis conditions.