Abstract: A filter press type electrolytic cell for the electrolysis of brine to produce chlorine and caustic includes a plurality of rectangular frames having U-shaped or channel-shaped walls, the open sides of each of which wall members face inwardly, and a downcomer tube in each frame for conducting product from near the top of the frame to the bottom thereof for withdrawal. The downcomer tubes are located near a framing side but are not within a framing channel. The openings of the framing walls are partially covered by cross members of the same material as the framing to improve the resistance thereof to distortion during closing of the cell. Utilization of the downcomer tubes, preferably of polytetrafluoroethylene for the catholyte compartment and titanium or titanium clad material for the anolyte compartment, allows the maintaining of the framing channel open so that inner walls thereof are electrolytically protected against corrosion.

Abstract: In filter press electrolytic cell assemblies, gasketing materials are frequently used for sealing the cell contents between individual frames. An improved design of gasket is disclosed, having a bulb profile at one surface with a hollow or indented profile on the opposite. Use of this specific profile gasket, positioned in properly molded or machined sealing grooves in the mating surfaces of electrolytic cell frame members, permits repeated disassembly and reassembly of cell frame components without leakage of electrolytic fluids between cell compartments, or leakage from cell interior to exterior.

Abstract: An electrolytic cell suitable for use in electrolyzing ionizable chemical compounds, particularly alkali metal halide brines and hydrohalic acids, which comprises a cell body having an anode compartment containing a porous anode and a cathode compartment containing a cathode said compartments being separated from each other by a prestretched, taut membrane barrier which is substantially impervious to gases and liquids and which is selected from a hydrolyzed copolymer of a perfluorinated hydrocarbon and a sulfonated perfluorinated hydrocarbon and a sulfonated perfluorovinyl ether, and a sulfostyrenated perfluorinated ethylene propylene polymer, said barrier being pretreated by hydrolyzing and stretching prior to insertion in the cell.Such cells can be operated at constant low voltage, and are not subject to erratic operating voltages which are due, in part at least, to the accumulation of gases between the anode and diaphragm.

Abstract: A molded electrolytic cell body or frame for housing electrodes and a membrane has a passageway therein communicating an anolyte drain header or manifold or an anolyte discharge header with the anolyte compartment of the cell, through which passageway a conductor of material resistant to electrolytic attack is passed to connect the liquid in the anolyte drain or discharge header with the anode. The conductor acts as a target anode and inhibits electrolytic damage to the anode, thereby lengthening its life.

Abstract: The voltage drop in a three compartment membrane cell used for the electrolysis of brine is diminished by treatment of the anolyte with acid, preferably hydrochloric acid, lowering the caustic concentration in the buffer zone and decreasing the current density for a period of time, during which the membrane adjacent to the anolyte is rejuvenated, and then resuming normal operations. In a similar manner the voltage drop in a two compartment membrane cell may be reduced, with the lowering of the caustic concentration being effected in the catholyte, preferably by dilution with water.

Abstract: A seal for preventing passage of fluid through an opening in an electrolytic cell wall through which a conductor for carrying electricity to or from a cell electrode passes includes as elements thereof a portion of the cell wall opening which is tapered so as to be larger at the outer part of the wall than at the inner part, silicone rubber in the narrower tapered opening part, an electrolyte-resistant rubber, such as neoprene, in the wider tapered opening part and means for pressing such rubber against the silicone rubber so as to help seal the silicone rubber against the tapered cell wall and the conductor. Preferably, the seal is a gas-tight seal and prevents hydrogen from escaping into the atmosphere from the catholyte compartment of an electrolytic cell for the electrolysis of brine.

Abstract: A cation-active permselective membrane of a hydrolyzed copolymer of a perfluorinated olefin and a fluorosulfonated perfluorovinyl ether, a modification thereof, or sulfostyrenated perfluorinated ethylene propylene copolymer is employed to dialytically pass metal hydroxide from an aqueous solution thereof containing metal halide halates, thereby purifying the metal hydroxide of the metal halide. The named cation-active permselective membrane materials resist deterioration by the halates, hydroxide and halide components of the solution being purified.The invention also includes a dialysis cell for effecting the purification.