Y. Ogata

On the oxidation of cyanide solutions with lead dioxide coated anode

Abstract The electrochemical oxidation of cyanide ion with and without coexistent metallic ions was studied. The PbO2-electrodeposited Ti anode was suitable for the purpose. The process required an excess amount of OH− since otherwise azulmin was formed by the side reaction. The interference effects of metallic ions (Cd, Cu, Fe and Zn) on the oxidation of cyanide were investigated. Of these, Fe ion was the most harmful.

Electrode Heat Balances of Electrochemical Cells Application to Water Electrolysis

This paper deals with a method of estimating single electrode heat balances during the electrolysis of molten NaCl-ZnCl2 in a cell using aβ-alumina diaphragm. By measuring the thermoelectric power of the thermogalvanic cells: (T) Na/β-alumina/NaCl-ZnCl2/β-alumina/Na(T+dT) and (T) C,Cl2/NaCl-ZnCl2/Cl2,C(T+dT) the single electrode Peltier heat for sodium deposition and for chlorine evolution at 370° C were estimated to be −0.026±0.001 JC−1 and+0.614±0.096 J C−1, respectively.

On the RuO2TiO2 interlayer of PbO2 electrodeposited Ti anode

Abstract The degradation mechanism of electrodeposited β-PbO 2 on the RuO 2 TiO 2 loaded Ti substrate was studied. The electric resistance of the PbO 2 anode was increased the Ti/Ru ratio of the interlayer and the current density of electrodeposition, probably due to oxidation of the interlayer at the initial stage of electrodeposition, so that the electric contact between PbO 2 and the interlayer might fail. The β-PbO 2 deposited anodes prepared carefully to avoid destructive oxidation of the interlayer were examined as the oxygen evolution electrode in 1 M H 2 SO 4 . The Ti substrate became passive, caused by permeation of oxygen through PbO 2 and the interlayer, when electrolysis was conducted for many hours. The service life time depended on the Ti/Ru ratio of the interlayer and the operating current density.

Studies of the pH of the membrane surface in a laboratory chlor-alkali cell

The pH on the surface of an ion-exchange membrane was measured with a microprobe in a laboratory scale chlor-alkali cell to study the leakage of OH− through the membrane. The solution pH in the vicinity of the membrane facing the anode was found to be considerably higher than that in the bulk solution because of penetration and leakage of OH−. The pH varied with the membrane type. This explains why the carboxylate membrane is not protonated and can be used as a separator in chlor-alkali cells.

Corrosion Behavior of Ni and Ni‐Based Alloys in Concentrated NaOH Solutions at High Temperatures

Corrosion behavior of SUS 310S austenitic stainless steel, Alloy 600, Monel 400, and Ni 200 and NaOH solutions in the concentration range 30-60% at high temperatures up to 166/sup 0/C was studied. In solutions containing dissolved oxygen or under oxidizing conditions, all the specimens examined were corroded seriously due to oxygen diffusion through the porous oxide layer consisting of ..beta..-Ni(OH)/sub 2/. In hydrogen-saturated solutions, on the other hand, these Ni alloys were corrosion resistant because nickel in the alloys was active to oxidation of hydrogen. The specimens were corroded by deaerated solution at high temperatures in which hydrogen evolution took place as the counterreaction. The corrosion rate controlled by the hydrogen formation reaction increased exponentially with the decrease of the Ni content in the alloy.

Effects of the Operating Pressure on the Performance of Water Electrolysis Cells at Elevated Temperatures

The influence of pressure on the performance and the thermal behavior of an alkaline water electrolyzer operated at elevated temperatures was studied. The pressure dependence of cell voltage was not significant. On the other hand, the effects of pressure on the thermal behavior were great depending on the operating conditions mainly caused by the suppression of water vaporization. The optimum conditions of the operating temperature and pressure are also discussed from an economic point of view.

Concentration dependence of thermoelectric powder in a molten salt system

Abstract This paper first presents thermodynamic considerations for the concentration dependence of the thermoelectric power in a molten salt system, and then presents experimental data for the Cu/Cu+ and Ag/Ag+ couples in a LiCl—KCl eutectic melt. The experimental data show good agreement with the derived thermodynamic equation. For the thermodynamic treatment, the approach of Forland and Ratkje was chosen, since it is thermodynamically rigorous.

On the Thermal Characteristics of Electrolytic Cell

Mathematical analysis of the heat balance of electrolytic cell was investigated. Experimental results with a verticaltype water electrolysis cell under normal conditions agreed with calculation. The water vaporization is a major factor of heat loss from the cell and, hence, it must be reduced. The thermal behavior of a water electrolysis cell was simulated under normal and pressurized conditions with the equations proposed. It was clarified that the hea loss from the cell could be reduced by increasing the operating pressure because the water vaporization was a large factor of heat dissipation at high temperatures. The effects of the thermal insulation and the emissivity of the cell wall were also discussed.