Abstract: This invention is directed to a membrane or diaphragm-free electrolytic cell device for removal of a metal(s) present as a contaminant(s) in waste water comprising a nonconductive cell box having an upper peripheral flange, anode and cathode bus bars located on said cell box below said flange, inlet and outlet means to pass the liquid through the electrodes contained in said box, means to space the anodes and cathodes contained within said cell box, a plurality of anodes having openings to permit the flow of waste water therethrough, a plurality of reticulate cathodes, and means connecting the anodes and cathodes, respectively, to said bus bars and to a source of electrical energy whereby the metal contaminant(s) present in such water are deposited on the reticulate cathodes predominantly.

Abstract: This disclosure is directed to the preparation of cohesive, self-sustaining electrode backing layers by a method comprising mixing from about 20 to about 50 weight parts of polytetrafluoroethylene (PTFE) having a particle size ranging from 0.05 to 0.5 micron with from about 50 to about 80 weight parts of a partially fluorinated carbon black of the formula CF.sub.x, where x is from about 0.1 to about 0.18 and having particles of a size ranging from about 50 to about 3000 angstroms to produce an electrode backing layer having a combination of enhanced electrical conductivity and hydrophobicity.

Abstract: This disclosure is directed to a process for extracting PTFE-wetting agent from PTFE particles containing small amounts of wetting agent in admixture with carbon particles comprising contacting said mixture with an organic liquid medium capable of extracting said wetting agent, and electrodes containing such extracted mixes. Also disclosed is a process for forming an electrode layer by depositing a soluble salt on a filter medium, depositing electrode layer material on said salt consolidating said electrode material and thereafter dissolving said salt.

Abstract: The present disclosure is directed to an electrode active layer or sheet containing from about 60 to about 85 wt. % active carbon in intimate admixture with 15 to 40 wt. % fibrillated PTFE. This electrode has improved strength and is capable of operation at high current density with resistance to mechanical failure due to blistering of the electrode, and to a process for producing same. The process is characterized by combining a dilute dispersion of smaller polytetrafluoroethylene particles with a suspension of catalyzed or uncatalyzed larger active carbon particles to discontinuously coat active carbon with PTFE; fibrillating same; comminuting said fibrillated PTFE/active carbon mix; and then rolling same into a self-sustaining, coherent sheet form. Alternatively, the sheet form can be provided by deposition of the heat treated polytetrafluoroethylenated active carbon on a filter paper or like medium.

Abstract: This disclosure is directed to a gas diffusion electrode, e.g., an oxygen (air) electrode, having a conductive, porous, sintered, plaque metal substrate containing generally spherically-shaped anchor site depressions on its active layer-contacting surface; an active layer containing catalyzed or uncatalyzed carbon particles and whose plaque-contacting surface includes anchor portions which interlock with the anchor site depressions and assist in securing the active layer to the plaque substrate, and a hydrophobic backing (wetproofing) layer in contact with the other surface of the active layer. The plaque is made by forming, e.g., by rolling or pressing, the metal powder, preferably silver, containing particulate extractable material on one face or surface thereof into a thin plaque; sintering the plaque containing the extractable material at temperatures of from about 1000.degree. to about 1300.degree. F.

Abstract: This disclosure is directed to a non-bleeding gas electrode for operation under the rigors of high current density and to the active layer thereof. This active layer is comprised of 60 to 90 weight percent high surface area, electroconductive carbon (with or without catalyst thereon), 10 to 40 weight percent particulate polytetrafluoroethylene (PTFE) and has pores sufficiently large to relieve internal hydrodynamic pressures thus preventing liquid being forced through the electrode wetproofing layer to the air side thereof. In addition such electrodes include a PTFE-containing wetproofing or backing layer secured on one side to said active layer and on the other side to a current distributor.

Abstract: This disclosure is directed to operating gas electrodes, e.g., oxygen (air) cathodes at "blow-through" pressures of oxygen-containing gas, viz., oxygen or air pressures exceeding the pressure(s) at which bubble-through of such gas occurs, which pressures result in savings due to reduced cathode potential (voltage) during operation. Depending upon the specific oxygen (air) cathode employed, the pressures required to obtain blow-through can vary widely. Usually, however, oxygen (air) pressures of 2 to 15 psig are satisfactory to accomplish blow-through.

Abstract: This disclosure is directed to a shutdown procedure for use in gas electrodes, e.g., oxygen (air) cathodes, which comprises imposing a nitrogen purge on the cell containing said electrode upon power shutdown and maintaining this nitrogen atmosphere (blanket) during the period of the shutdown. It has been discovered that the use of this procedure enables maintaining of the low voltage operation achieved prior to power shutdown upon restart of the cell when the power has been restored.

Abstract: The present disclosure is directed to a process for treating gas electrodes containing a wetproofing (backing) layer which contains a polytetrafluoroethylene (PTFE) in conjunction with a water-soluble pore-forming agent and a PTFE-containing active layer to preserve and enhance their structural integrity which comprises contacting the electrode first with an alkylene polyol, or other water-soluble organic material having a plurality of hydroxyl groups, at temperatures ranging from about 50.degree. to about 100.degree. C. for a sufficient period of time to thoroughly wet the PTFE-containing active layer thereof, and thereafter contacting the thus-treated electrode with water in one or more washing steps to substantially remove the pore-forming agent. Between the hot soak with the alkylene polyol, or equivalent material, and the water wash(es), the electrode can optionally be dried.

Abstract: The present invention is directed to fluid-tight, high current density-stable electrical contacts for conductively joining components of an electrolytic cell, e.g., anode and cathode plates, comprising a spring-like spiral or coil of electroconductive metal or metal alloy having an electrically conductive or nonconductive oxidation-resistant filler (seal) between the spiral rings and wherein said spiral rings are positioned so that their edges and common longitudinal axis are substantially perpendicular to the faces of the cell components.

Abstract: The present disclosure is directed to an improved fibrillated matrix-type active layer for an electrode of improved strength and durability and capable of operation at high current density with enhanced resistance to mechanical failure, and to a process for producing such improved active layers. The process is characterized by alternately or simultaneously producing two components; combining the components; shear blending (fibrillating) the mixture; drying; chopping to a fine powder form, and rolling into a self-sustaining, coherent shear form. Alternatively, the active layer can be formed by wet deposition of the powder on a filter paper or like medium.The term "matrix" as used herein means that the active carbon particles are present within an unsintered network of carbon black/PTFE (fibrillated) material.

Abstract: A strengthened fiber diaphragm and method for making such a diaphragm for use in electrochemical cells, the strengthening being accomplished through solution introduction of a zirconium compound into the fabric of the diaphragm.

Abstract: This disclosure is directed to an asymmetric woven wire mesh current distributor for an electrode containing more conductive elements (portions) in one direction than in the other direction when installed in use in an electrode so that the greater number of wires is perpendicular to the major current feeder bars and span the narrow part (conductive path) of a rectangular air cathode. In accordance with the preferred embodiment of this invention, the current distributor is a woven wire mesh wherein the numerical ratio between the number of said perpendicular wires to said parallel wires ranges from about 1.5 to about 3:1.

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 essentially only oxygen is evolved at the surface thereof, preferably at a rate of at least about 4.66 millimoles per square meter per hour without evolution of any chlorine. Periodic current reversal is effected to forestall biofouling upon any cathode utilized in implementing the instant invention.

Abstract: This disclosure is directed to a one pass process for forming a porous, uniaxially oriented polytetrafluoroethylene sheet which is coherent and suitable for utilization as an electrode backing (wetproofing) sheet and the resulting backing sheet. Particulate PTFE is blended in an organic liquid medium to form a dispersion to which a pore-forming agent is added. After mixing, the organic liquid is removed and the dry mix is fibrillated, chopped and formed into a sheet by passing it once through heated rollers.

Abstract: This disclosure is directed to a process for extracting PTFE-wetting agent from PTFE particles containing small amounts of wetting agent in admixture with carbon particles comprising contacting said mixture with an organic liquid medium capable of extracting said wetting agent, and electrodes containing such extracted mixes. Also disclosed is a process for forming an electrode layer by depositing a soluble salt on a filter medium, depositing electrode layer material on said salt consolidating said electrode material and thereafter dissolving said salt.

Abstract: This disclosure is directed to strengthening carbon black-particulate "Teflon" (PTFE) mixes destined to be formed into active layers in air cathodes, which comprises forming the carbon black-particulate Teflon mix; fibrillating said mix along with a substantial quantity of soluble pore-forming agent; adding polytetrafluoroethylene (PTFE) fibers while chopping said fibrillated mix; and thereafter rolling said chopped fibrillated mix containing said PTFE fibers into sheet form.

Abstract: The invention is directed to an electrolytic process for converting alkali metal carbonates to alkali metal hydroxides at high current efficiencies.

Abstract: This disclosure is directed to preparing deashed, precious metal catalyst-containing, partially fluorinated active carbon particles of the formula CF.sub.x, where x ranges from 0.1 to about 0.18, preferably using either platinum or silver as the catalyzing material, which can be incorporated into an active layer component of a gas electrode, e.g., an oxygen (air) cathode suitable for use in a chlor-alkali electrolytic cell for producing chlorine and caustic while conserving electrical energy. These particles are deashed to have a B.E.T. surface area of at least 600 m.sup.2 /g and contain less than about 4 weight percent ash. Active electrode layers containing such particles demonstrate an unusually desirable combination of resistance to corrosion, retention of conductive properties and retention of catalytic surface area.

Abstract: An electrode for use in electrolytic processes comprises a substrate of film-forming metal such as titanium having a porous electrocatalytic coating comprising at least one platinum-group metal and/or oxide thereof possibly mixed with other metal oxides, in an amount of at least about 2 g/m.sup.2 of the platinum-group metal(s) per projected surface area of the substrate. Below the coating is a preformed barrier layer constituted by a surface oxide film grown up from the substrate. This preformed barrier layer has rhodium and/or iridium as metal or compound incorporated in the surface oxide film during formation thereof in an amount of up to 1 g/m.sup.2 (as metal) per projected surface area of the substrate.