Chloride Electrolyte-Sintered Cathode Anode System Chemism Study of Titanium Dioxide in Calcium Chloride

2008 ◽  
Vol 59 (5) ◽  
Author(s):  
Dragos Taloi ◽  
Mihai Tarcolea ◽  
Vasile Soare ◽  
Marian Burada ◽  
Ion Carcea
Keyword(s):  
Titanium Dioxide ◽  
Liquid Electrolyte ◽  
Electrochemical Process ◽  
Electrochemical Reactions ◽  
Electrolysis Cell ◽  
Metallic Titanium ◽  
General Reaction ◽  
Free Gibbs Energy ◽  
Solid Titanium ◽  
Mathematical Processing

The electrochemical process of the solid titanium dioxide develops in the complex system: TiO2 (solid, sintered cathode) � CaCl2 (liquid, electrolyte) � C (anode, graphite). As a consequence of the chemical and electrochemical reactions which take place in this system, with determined conditions of temperature and potential, are finally formed solid metallic titanium (at the cathode) and oxygen (at the anode). The general reaction of the process is: TiO2(s) = Ti(s)+O2(g). A series of other reactions, implying the presence of other components (elements and compounds), as Ca, CaO, CaTiO3, C, CO, CO2, etc., are possible in certain conditions and stages of the process. In the paper are analyzed the main reactions which occur in the process, by their thermodynamic study. Through mathematical processing of thermodynamic data for the main reactions in the system, recently published in the literature, there was determined the temperature dependence of the Free Gibbs Energy, and based on it the values of the electrode potential were computed. In this manner was possible to prove that chemical reactions that could not spontaneously evolve, can develop in the electrochemical process by means of a corresponding voltage applied on the electrolysis cell.

Co-electrolysis of H2O and CO2in a solid oxide electrolysis cell with hierarchically structured porous electrodes

2015 ◽  
Vol 3 (31) ◽  
pp. 15913-15919 ◽  
Author(s):  
Chenghao Yang ◽  
Jiao Li ◽  
James Newkirk ◽  
Valerie Baish ◽  
Renzong Hu ◽  
...  
Keyword(s):  
Freeze Drying ◽  
Porous Electrode ◽  
Tape Casting ◽  
Porous Electrodes ◽  
Solid Oxide ◽  
Electrochemical Reactions ◽  
Electrolysis Cell ◽  
Straight Channel ◽  
Solid Oxide Electrolysis ◽  
Solid Oxide Electrolysis Cell

A solid oxide electrolysis cell with novel asymmetric-porous structured electrodes has been fabricated by freeze-drying tape-casting and impregnation methods. The straight channel-like pores in the porous electrode facilitate mass transport while the nano- or sub-micron-sized catalysts promote the electrode electrochemical reactions.

scholarly journals Modeling of the Electrochemical Reactions at the Electrode-Electrolyte Interface of Nickel/Metal Hydride Batteries by an Equivalent Electrical Circuit

2019 ◽  
Vol 4 (4) ◽  
pp. p241
Author(s):  
M. Ben Moussa ◽  
M. Abdellaoui
Keyword(s):  
Electric Circuit ◽  
Electrochemical Process ◽  
Electrical Circuit ◽  
Electrochemical Reactions ◽  
Nickel Metal ◽  
Nickel Metal Hydride ◽  
Electrolyte Interface ◽  
Battery Electrode ◽  
Nimh Battery ◽  
Good Agreement

Based on the experimental impedance spectra, the electrochemical reactions that are deposed at the electrode-electrolyte interface can be modeled by equivalent electrical circuits. Each element used in the circuit must have a physical correspondence in the electrochemical system. In this work, a model has been proposed to a NiMH battery electrode to describe, in detail, the electrochemical process at the interface of this electrode. The theoretical impedance of a proposed circuit is a function of several variables. These adjusted variables to reach a good agreement between the theoretical spectra and the experimental spectra in the studied frequency. The Z-simplex software allows refining the experimental results. These results show a good superposition between the experimental spectra and the theoretical spectra corresponding to the proposed electric circuit. This leads to the conclusion that the proposed circuit describes the phenomena that take place at the interface of the hydride electrode.

Reduction of Titanium Dioxide to Metallic Titanium Conducted under the Autogenic Pressure of the Reactants

2009 ◽  
Vol 48 (15) ◽  
pp. 7066-7069 ◽  
Author(s):  
Michal Eshed ◽  
Alexander Irzh ◽  
Aharon Gedanken
Keyword(s):  
Titanium Dioxide ◽  
Metallic Titanium

Processes for the Treatment of NORM and TENORM

2003 ◽  
Author(s):  
Andreas Vesely
Keyword(s):  
Rare Earth ◽  
Sodium Hydroxide ◽  
Sodium Hydroxide Solution ◽  
Selective Dissolution ◽  
Electrochemical Process ◽  
Electrolysis Cell ◽  
Molybdenum Oxides ◽  
Radioactive Elements ◽  
Rare Earth Compound ◽  
Aluminum Compounds

By contract with the Austrian government, the ARC is treating radioactive waste from research institutions and industries. In the last years, one focus was the development of processes for the treatment of NORM and TENORM. Our goal in developing such processes is to recycle valuable compounds for further industrial usage and to concentrate the radioactive elements as far as possible, to save space in the waste storage facilities. Austria is an important producer of tungsten-thoria- and tungsten-molybdenum-thoria-cermets. Scrap is generated during the production process in the form of turnings and grinding sludge and dust. Although big efforts have been undertaken to replace Thorium compounds, waste streams from past production processes are still waiting for treatment. The total amount of this waste stored in Austria may be estimated to be approx. 100 tons. In close co-operation with the tungsten industries, recycling processes were tested and further developed at ARC in laboratory, bench scale and pilot plants. Three different approaches to solve the problem were studied: Dissolution of tungsten in molten iron in an arc or induction furnace, thus producing an Fe-W or Fe-W-Mo alloy. Slag is produced upon the addition of lime and clay. This slag extracts nearly all of the Thorium contained in the metal melt. Selective dissolution of Tungsten in aqueous alkaline medium after oxidation of the metal to the hexavalent state by heating the scrap in air at temperatures of 500°C to 600°C. The resulting oxides are treated with sodium hydroxide solution. Tungsten and Molybdenum oxides are readily dissolved, while Thorium oxide together with silicon and aluminum compounds remain insoluble and are separated by filtration. Sodium tungstate solution is further processed by the usual hydrometallurgical tungsten mill process. Oxidation and dissolution of Tungsten can be achieved in one step by an electrochemical process. Thus, thoriated Tungsten scrap is used as an anode in an electrolysis cell, while sodium hydroxide or ammonia serve as electrolyte. After dissolution of Tungsten, the solids are separated from the liquid by filtration. With the electrochemical process, treatment of Tungsten-Thoria scrap can be achieved with high throughput in rather small reactors at moderate temperatures and ordinary pressure. The Tungsten solution exhibits high purity. Another process which we examined in detail is the separation of radium from rare earth compounds. Radium was separated by co-precipitation with barium sulfate from rare earth chloride solutions. The efficiency of the separation is strongly pH-dependent. Again, the valuable rare earth compound can be reused, and the radioactive elements are concentrated.

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