Abstract: A method and apparatus for reducing electrowinnable metal ion concentration to a low level in a process stream and recovering the metal electrolytically. Low concentration metal ions from the process stream are recovered in an ion exchanger and then recaptured from the ion exchanger into a relatively small volume of regeneration fluid. The regeneration fluid, pregnant with the metal ions, is electrolyzed in a particulate bed electrolytic cell to a relatively low level of metal ion concentration, and the regeneration fluid is then available for reuse in a further ion exchanger regeneration.

Abstract: Normally solid copolymers of a fluorinated vinyl monomer and a perfluorinated vinyl compound having a carboxyl and/or sulfonyl group attached directly to the perfluorinated vinyl group or indirectly through an alkyl or ether linkage have been found to be soluble in low molecular weight polymers of perhalogenated alkyl ethers, low molecular weight polymers of perhalogenated alkyls and perfluoro kerosenes, each of said solvent materials having boiling points between about 200.degree. C. and 350.degree. C. The copolymeric material dissolved in accordance with the instant invention can readily be resolidified by solvent removal and hydrolyzed or converted to the salt form to become a cation exchange material having an equivalent weight in the range of 1000 to 1600.

Abstract: Concentrated alkali metal hydroxide substantially free of alkali metal halide and other impurities is produced by the electrolysis of an alkali metal halide solution in an electrolytic cell having a dimensionally stable anode and a metal cathode separated by an electrically conductive stable selectively permeable hydrated cation ion-exchange membrane film of a fluorinated copolymer having pendant sulfonic acid groups or derivatives of such groups. The membrane film is capable of use at high temperatures and under severely corrosive chemical conditions for extended periods without degradation.

Abstract: PCT No. PCT/EP79/00020 Sec. 371 Date Nov. 28, 1979 Sec. 102(e) Date Nov. 26, 2979 PCT Filed Mar. 27, 1979 PCT Pub. No. WO79/00840 PCT Pub. Date Oct. 18, 1979An electrode for electrolytic processes such as the recovery of uranium dioxide from seawater comprises an electrically-conductive corrosion-resistant substrate having an electrocatalytic coating which is preferably a mixture of 30 to 80 parts by weight of platinum, 20 to 70 parts by weight (as Mn metal) of .beta.--MnO.sub.2 and 2 to 10 parts by weight (as Sn metal) of tin dioxide.

Abstract: Reduction of silicate levels in alkali metal choride containing industrial waste streams to less than 20 ppm provides waste brine streams suitable for use in the electrolytic production of chlorine and alkali metal hydroxide.

Abstract: Normally solid copolymers of a fluorinated vinyl monomer and a perfluorinated vinyl compound having a carboxyl and/or sulfonyl group attached directly to the perfluorinated vinyl group or indirectly through an alkyl or ether linkage have been found to be soluble in low molecular weight polymers of perhalogenated alkyl ethers, low molecular weight polymers of perhalogenated alkyls and perfluoro kerosenes, each of said solvent materials having boiling points between about 200.degree. C. and 350.degree. C. The copolymeric material dissolved in accordance with the instant invention can readily be resolidified by solvent removal and hydrolyzed or converted to the salt form to become a cation exchange material having an equivalent weight in the range of 1000 to 1600.Membrane coated cathodes can be formed using the dissolved copolymeric material and may be made by casting or coating a foraminous cathode followed by removal of the solvent to result in a continuous, pore-free coating of membrane on the cathode.

Abstract: Electrodes for electrolytic processes comprise an electrically-conductive and corrosion-resistant substrate, having a coating thereon which contains a solid solution of tin dioxide and bismuth trioxide, preferably in a ratio of 9:1 to 4:1 by weight of the respective metals. This solid solution may form the active coating or an intermediate layer covered with other electrocatalytic materials or may be included in a multi-component coating having selective properties for halogen evolution and oxygen inhibition.

Abstract: An electrochemical cell comprises a housing (1,2) divided by a perforated generally horizontal plate (3) into an upper chamber (4) and a lower chamber (5). Bipolar electrodes (19, 21) are disposed in the upper chamber (4) above perforations (23) in the plate (3), between electrolyte inlet and outlet weirs (11, 13) for flowing electrolyte over the plate (3). The lower chamber (5) is a gas-supply chamber for passing a gas, e.g. propylene, up through the perforations (23), so as to bubble the gas through electrolyte (e.g. NaBr solution) on the plate (3) and into the upper gas-collection chamber (4). A reactor may be formed by stacking several cells with their electrolyte flows in cascade. The cell is particularly suitable for electro-organic syntheses involving a gaseous reactant.

Abstract: An electrode especially for the production of chlorates and perchlorates comprising an electrically-conductive corrosion-resistant substrate having an electrocatalytic coating which is preferably a mixture of 40 to 85 parts by weight of platinum, 0 to 20 parts by weight of palladium and 15 to 40 parts by weight (as tin metal) of tin dioxide.

Abstract: Normally solid copolymers of a fluorinated vinyl monomer and a perfluorinated vinyl compound having a carboxyl and/or sulfonyl group attached directly to the perfluorinated vinyl group or indirectly through an alkyl or ether linkage have been found to be soluble in low molecular weight polymers of perhalogenated alkyl ethers, low molecular weight polymers of perhalogenated alkyls and perfluoro kerosenes, each of said solvent materials having boiling points between about 200.degree. C. and 350.degree. C. The copolymeric material dissolved in accordance with the instant invention can readily be resolidified by solvent removal and hydrolyzed or converted to the salt form to become a cation exchange material having an equivalent weight in the range of 1000 to 1600.When these cation exchange materials in the salt form become damaged or contaminated during operation, for example in an electrochemical cell, they may now be reclaimed rather than discarded.

Abstract: Biofouling and scale control in conductive aqueous systems is effected on metal, preferably valve metal such as titanium, surfaces on which such fouling normally occurs by applying thereto a stable electrocatalytic coating, anodically polarizing said valve metal coating such that only oxygen is evolved at the surface thereof, preferably at a rate at least about 4.66 millimoles per square meter per hour without evolution of any chlorine.

Abstract: Disclosed is a monopolar membrane cell in which identical anode and cathode pans are stamped from bimetallic laminate material in which an electrolyte resistant material is utilized on the inside of the electrolytic cell and a highly conductive metal is utilized on the outside thereof. This design results in a substantial lowering of the voltage drop due to resistance through the anode and cathode pans of membrane cells.

Abstract: Novel oxygen selective electrode comprising a coating on said anode consisting of delta manganese dioxide. This outer coating on the anode may be placed on the anode electrochemically by electrolyzing an acid saline solution having dissolved therein sufficient manganous chloride. Sufficient manganese dioxide is plated on said anode when the chlorine evolution essentially ceases during electrolysis.

Abstract: This invention relates to the art of electrowinning and, more particularly, to a process for recovering zinc which is leached from an alloy coating of nickel and zinc which has previously been deposited on cathodes of an electrolytic cell used in the electrolysis of alkali metal halides. Further, a method of utilizing the recovered zinc for control of the zinc content of the nickel-zinc plating solution is disclosed.

Abstract: Disclosed are methods of operation for oxygen electrodes which maximize the power efficiency available from such oxygen electrodes while minimizing the voltage necessary to operate such oxygen electrodes. These methods include control of the pressure of the air feed side of the oxygen electrode, control of the total flow of the air feed side, the humidification of the air feed side of the oxygen electrode and the elimination of CO.sub.2 from the air feed to the oxygen electrode to increase the lifetime of such electrodes as applied to a chlor-alkali electrolytic cell.

Abstract: In an electrolytic cell of the membrane type wherein the anolyte and catholyte are separated by a hydraulically impermeable membrane, the improvement comprising limiting the hydraulically impermeable membrane portion of the divider between anolyte and catholyte chambers to that area which is between the active areas of the anode and cathode while all other areas between catholyte and anolyte chambers are nonpermeable so as to minimize back-migration of undesirable ions which decrease overall current efficiency. Specifically, in a chlor-alkali cell an electrode would be enclosed in a fluorinated ethylene propylene enclosure having window-like openings therein made from Nafion type hydraulically impermeable cation exchange membrane, said window-like openings exposing only active electrode areas.

Abstract: An improved anode and base assembly for diaphragm type electrolytic cells is disclosed. In the present embodiment, downwardly facing annular portions at the base of the anode risers of dimensionally stable anodes of the type well-known in the art are welded from below directly to a metal cell base cover which seals the electrolyte contained within the cell from the cell base which is generally of copper or aluminum, thereby eliminating corrosion problems associated with leaks in the rubber gaskets or blankets formally used between the anode risers and the cell base.

Abstract: Disclosed is an electrode for use in electrochemical processes wherein a metal substrate made of a valve metal such as titanium carries a semi-conducting intermediate coating consisting of a combination of tin and antimony oxides laid down upon the valve metal substrate in a series of layers and a top coating consisting of an oxide selected from the group of chromium, manganese, iron, cobalt, nickel, molybdenum or tungsten applied in a series of layers.

Abstract: Concentrated alkali metal hydroxide substantially free of alkali metal halide and other impurities is produced by the electrolysis of an alkali metal halide solution in an electrolytic cell having a dimensionally stable anode and a metal cathode separated by an electrically conductive stable selectively permeable hydrated cation ion-exchange membrane film of a fluorinated copolymer having pendant sulfonic acid groups or derivatives of such groups. The membrane film is capable of use at high temperatures and under severely corrosive chemical conditions for extended periods without degradation.

Abstract: Novel oxygen selective electrode comprising a coating on said anode consisting of delta manganese dioxide. This outer coating on the anode may be placed on the anode electrochemically by electrolyzing an acid saline solution having dissolved therein sufficient manganous chloride. Sufficient manganese dioxide is plated on said anode when the chlorine evolution essentially ceases during electrolysis.