Shuji Nakamatsu

Electrolytic decomposition of amaranth dyestuff using diamond electrodes

The electrolytic decomposition of an amaranth dyestuff solution using several combinations of electrodes with diamond and platinum is reported. It is observed that a portion of the amaranth is decomposed on the cathode surface while the other portion is decomposed to lower molecular weight components on the anode surface. The decolourizing rate is higher at diamond electrodes used as the anode and the cathode than with other combinations. This electrode combination also shows a rapid decrease in total organic carbon concentration. Acetic acid and oxalic acid are detected as the intermediate substances, and CO2 gas is generated as a final product corresponding to the decrease in the oxalic acid concentration.

A new method for the electrolysis of sodium chloride using a β-alumina-molten salt system

This paper is concerned with a new process for NaCl electrolysis. The catholyte is molten sodium hydroxide, containing a small quantity of water. The anolyte is the molten mixture of sodium chloride and zinc chloride. As a diaphragm, sodium ion conducting β-alumina is used. By the electrolysis, chlorine, sodium hydroxide and hydrogen are obtained almost quantitatively from sodium chloride and water. The operating temperature is about 330° C. A terminal voltage of 5 V at 40 A dm−2 is estimated from the experimental data and by numerical calculation. This process is very promising on the basis of the current efficiency and estimated voltage balance data.

A molten salt electrolytic process for recovering chlorine and ammonia from ammonium chloride. II

Various electrolytic methods were examined for recovering chlorine, hydrogen and ammonia from by-product ammonium chloride produced in the ammonium chloride-soda process. Two methods, one based on an aqueous electrolysis and the use of an ion exchange membrane, and the other employing a molten metal cathode were considered possible. This series of papers aims at a detailed description of the latter process, which seems more interesting from the viewpoint of industrial exploitation. This paper briefly reviews the other electrolytic processes before describing the principle of the molten salt process and the study of the reaction between ammonium chloride and liquid metals.