• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.12 no.3
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• pp.245-251
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• 2014

Pyroprocess for treating spent nuclear fuels has been developed based on electrochemical principles. Process simulation is one of the important methods for process development and experimental data analysis and it is also a necessary approach for pyroprocessing. To date, process simulation of pyroprocessing has been focused on electrorefining and there have been not so many investigations on electrolytic reduction. Electrolytic reduction, unlike electrorefining, includes specific features of gas evolution and porous electrode and, thus, different equations should be considered for developing a model for the process. This study summarized required concepts and equations for electrolytic reduction model development from thermodynamic, mass transport, and reaction kinetics theories which are necessitated for analyzing an electrochemical cell. An electrolytic reduction cell was divided and equations for each section were listed and, then, boundary conditions for connecting the sections were indicated. It is expected that those equations would be used as a basis to develop a simulation model for the future and applied to determine parameters associated with experimental data.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.352-359
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• 2005

This work has studied the changes of pH in both of anodic and cathodic chambers of a divided cell due to the electrolytic split of water during the ammonia decomposition to nitrogen, and has studied the continuous decomposition characteristics of ammonia in a multi-cell stacked electrolyzer. The electrolytic decomposition of ammonia was much affected by the change of pH of ammonia solution which was caused by the water split reactions. The water split reaction occurred at pH of less than 8 in the anodic chamber with producing proton ions, and occurred at pH of more than 11 in the cathodic chamber with producing hydroxyl ions. The pH of the anodic chamber using an anion exchange membrane was sustained to be higher than that using a cation exchange membrane, which resulted in the higher decomposition of ammonia in the anodic chamber. By using the electrolytic characteristics of the divided cell, a continuous electrolyzer with a self-pH adjustment function was newly devised, where a portion of the ammonia solution from a pHadjustment tank was circulated through the cathodic chambers of the electrolyzer. It enhanced the pH of the ammonia solution fed from the pH-adjustment tank into the anodic chambers of the electrolyzer, which caused a higher decomposition yield of ammonia. And then, based on the electrolyzer, a salt-free ammonia decomposition process was suggested. In that process, ammonia solution could be continuously decomposed into the environmentally-harmless nitrogen gas up to 83％, when chloride ion was added into the ammonia solution.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1361-1362
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• 2007

There is great interest in the applicability of electrogenerated hydrogen peroxide to a wide variety of industrial processes, usually involving oxidation of organics. Hydrogen peroxide is now employed for the bleaching of mechanical pulp and the bleaching of chemical pulp in the pulp and paper industry, thus displacing the traditional alkaline treatments with chlorine-based chemicals. This psper reperts a comparative study of $H_{2}O_{2}$ electogeneration on gas-diffusion electrode in divided cell with several $Nafion^{(R)}$ protonexchange membranes, Russian cation-exchange membrane MK-40 and SPEEK membrane. The influence of different PEMs on electrochemical cell voltage, current efficiency and energy consumption of hydrogen peroxide electrogeneration has been stadied.

• Journal of the Korean Electrochemical Society
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• v.10 no.4
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• pp.235-238
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• 2007

There is great interest in the applicability of generated hydrogen peroxide to a variety of industrial processes, usually involving oxidation of organics. Hydrogen peroxide is now employed for the bleaching as well as mechanical and chemical treatment in the pulp and paper industries. It addition, it is considered as an agent to displace the traditional alkaline treatments with chlorine-based chemicals. This paper reports a comparative study of $H_2O_2$ electogeneration on gas-diffusion electrode in divided cell with several $Nafion^{(R)}$ proton-exchange membranes, Russian cation-exchange membrane MK-40 and SPEEK membrane. The influence of different PEMs on electro-chemical cell voltage, current efficiency and energy consumption of hydrogen peroxide generation has been studied.

• Korean Chemical Engineering Research
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• v.58 no.2
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• pp.319-324
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• 2020

Electroconvective instability is a non-linear transport phenomenon which can be found in ion-selective transport system such as electrodialysis, Galvanic cell and electrolytic cell. The instability is triggered by the fluctuation of space charge layer in adjacent of ion-selective surface, leading to increase of mass transport rate. Thus, in the aspect of mass transport, the instability has an important meaning. Although recent experimental techniques have opened up an avenue to direct visualize the instability, fundamental investigations have been conducted in limited area due to several experimental limitations. In this work, the electroconvective instability under potentiostatic mode was solved by numerical method in order to demonstrate correlation between current-time curve and the instability behavior. By rigorous time-resolved analysis, the transition behaviors can be divided into three stages; formation of space charge layer - growth of electroconvective instability - steady state. Furthermore, scaling laws of transition time were numerically obtained according to applied voltage as well.