Abstract: High current efficiency can be obtained in an electrolytic cell by inducing turbulence in the catholyte preferably by utilizing a gas-directing cathode and cation-permselective membrane combination. There is disclosed a process for electrolysis, particularly, the electrolysis of an alkali metal chloride such as sodium chloride to produce chlorine and sodium hydroxide. Said cell has a cathode and an anode divided into catholyte and anolyte compartments by a cation-permselective membrane. Turbulence inducing means such as a gas-directing cathode provides turbulence in said catholyte at the surface of said membrane by directing gas evolving on said cathode toward or away from said membrane. Multicell arrangements are also disclosed wherein said cells are connected in series.

Abstract: In a chlor-alkali electrolytic cell in which an aqueous alkali metal chloride solution is electrolyzed, said electrolytic cell having an anode compartment containing an anode and a cathode compartment containing a cathode separated by a substantially fluid impervious membrane barrier consisting of a copolymer of tetrafluoroethylene and a sulfonated perfluorovinyl ether, the formation of alkali metal chlorates in the anode compartment is reduced by operating the chlor-alkali cell at high salt conversions greater than 40% and preferably between about 60% and about 80% conversion.

Abstract: A practical method of electrolyzing sodium chloride brine on a commercial scale, obtaining in good yield a caustic product exceptionally low in salt content, is provided. The process necessarily involves working with a brine of lower calcium-ion content than is ordinarily used, using dimensionally stable anodes, using, preferably but not necessarily, a heat-treated ion-exchange membrane as a separator within the cell, and periodically taking action to reduce the cell voltage, by reducing the current or interrupting it, alone or with a concomitant flushing of the catholyte portion of the cell.

Abstract: Membranes for use in chlor-alkali cells, made of a copolymer of tetrafluoroethylene and sulfonylfluoride perfluorovinyl ether, have their selectivity improved, with resulting substantial decrease in consumption of electric power per mole of sodium hydroxide produced, by being heat-treated at 100 to 275.degree. Centigrade for several hours to four minutes. The current efficiency is substantially increased, and the power consumption, per unit of sodium hydroxide produced, is usually decreased by about 10 percent or more.