Abstract: A multi-cell electrolyzer comprising a plurality of unit cells, each of which is composed of an anode chamber containing an anode and a cathode chamber containing a cathode and a cation exchange membrane for partitioning said unit cell into said anode chamber and said cathode chamber, and each of which is adapted to have an internal pressure maintained at a level higher than the atmospheric pressure in operation of the electrolyzer, said plurality of unit cells being arranged in series and adapted to be energized through a plurality of current lead plates, and rigid multi-contact electrically conductive means provided between the adjacent unit cells and/or between each current lead plate and the unit cell adjacent thereto, thereby establishing electrical connection between the adjacent unit cells and/or between each current lead plate and the unit cell adjacent thereto.

Abstract: A process for the production of sodium chlorate comprising electrolyzing an aqueous sodium chloride solution in a diaphragmless sodium chlorate cell, characterized in that an aqueous sodium chloride solution containing, as impurities, calcium, magnesium, barium and the like is contacted with a chelating ion exchange resin to remove the impurities and the resulting saline solution is supplied into a diaphragmless sodium chlorate cell, thereby enabling sodium chlorate to be produced at a stable electrolytic voltage.

Abstract: High purity aqueous alkali hydroxide solutions containing predetermined, low concentrations of alkali metal halide are obtained in the anode compartment of an electrolytic cell using a cationic ion exchange membrane by conducting the electrolysis under controlled conditions such that the difference between the concentration of alkali metal halide in the anode compartment and the limiting concentration of alkali metal halide in the anode compartment is within a defined range.

Abstract: In a process for electrolysis of sodium chloride in an electrolytic cell divided into the anode chamber and the cathode chamber by a cation exchange membrane, well brine is used as the starting material for the electrolysis and the dilute aqueous sodium chloride solution formed as the result of the electrolysis is subjected to concentration for re-use as the starting material.

Abstract: Alkali metal hydroxide is produced by electrolysis of alkali metal chloride according to an improved diaphragm process wherein plural cationic ion-exchange membranes are used to divide an electrolytic cell into an anode compartment, at least one middle compartment and a cathode compartment. The ion-exchange membrane confronting anode is preferably substantially resistant to anode reaction products such as chlorine or chlorates. Alkali formed by electrolysis is recovered from cathode compartment or alternatively a portion thereof may be taken out from middle compartments at various concentrations. Alkali metal hydroxide can be produced in high purity and high concentration with excellent efficiency.