Abstract: A process is described for recovering phosphorus from pond sludge found in ponds located near phosphorus plants. An aqueous solution of the sludge, which has a phosphorus concentration in the range of 5% to 70% by weight, is heated at a temperature in the range of 165.degree. F. to 212.degree. F., preferably for about 1/2 hour to about 6 hours, washed with water at an elevated temperature, and then reheated. A phosphorus layer having an enhanced concentration of recoverable elemental phosphorus is formed as a result of this process.

Abstract: A porous polyfluoroalkylene sheet, preferably of polytetrafluoroethylene, which is suitable for use as a stable low voltage separator or diaphragm in an electrolytic cell, such as one employed for the electrolysis of brine, without being subject to an objectionable voltage increase upon use, is of a thickness in the range of about 0.2 to 2 mm., a porosity in the range of about 70 to 90% and of pore sizes within a range up to about one mm. in diameter, with a pore size distribution such that the pores of a diameter about 0.1 micron (or less) are less than 10% of the total pore volume and the volume of those of about one to ten microns is a substantial part, e.g. 50%, of the total pore volume, and with the ratio of the numbers of such pores in the lower size range to those in the upper range being less than about 30. Limiting the 0.

Abstract: A foraminous protective cathode for diaphragm-type electrolytic cells having a steel cathode and polymeric microporous separator reduces or eliminates separator plugging thereby increasing useful life-expectancy of the separator. The protective cathode positioned between the primary steel cathode and separator has an electroconductive metallic surface of nickel, cobalt, copper, chromium, noble metals, noble metal oxides or mixtures thereof.

Abstract: A porous polyfluoroalkylene sheet, very preferably of polytetrafluoroethylene, which is suitable for use as a separator in an electrolytic cell, such as one used for the electrolysis of brine, has a porosity in the range of 70 to 90%, a thickness in the range of 0.2 to 3.5 mm. and at least one of (a) an A X-ray ratio in the range of 0.1 to 0.35 and (b) a B X-ray ratio in the range of 0.75 to 0.98. Preferably the A X-ray ratio is in the range of 0.1 to 0.3, the B.sub.2 X-ray ratio is in the range of 0.75 to 0.98 and the B.sub.1 X-ray ratio is in the range of 0.1 to 0.32. The porous sheets are incorporated in separators or diaphragms for electrolytic cells and the uses of such separators and cells in electrolysis processes, preferably in the electrolysis of brine, are described. Also shown in the specification are a method for the manufacture of the porous sheets and a method for ascertaining which milled, sintered and leached porous sheets are more suitable for use in electrolytic processes.

Abstract: A porous polyfluoroalkylene sheet, preferably of polytetrafluoroethylene, which is suitable for use as a stable low voltage separator or diaphragm in an electrolytic cell, such as one employed for the electrolysis of brine, without being subject to an objectionable voltage increase upon use, is of a thickness in the range of about 0.2 to 2 mm., a porosity in the range of about 70 to 90% and of pore sizes within a range up to about one mm. in diameter, with a pore size distribution such that the pores of a diameter about 0.1 micron (or less) are less than 10% of the total pore volume and the volume of those of about one to ten microns is a substantial part, e.g. 50%, of the total pore volume, and with the ratio of the numbers of such pores in the lower size range to those in the upper range being less than about 30. Limiting the 0.

Abstract: A porous polyfluoroalkylene sheet, very preferably of polytetrafluoroethylene, which is suitable for use as a separator in an electrolytic cell, such as one used for the electrolysis of brine, has a porosity in the range of 70 to 90%, a thickness in the range of 0.2 to 3.5 mm. and at least one of (a) an A X-ray ratio in the range of 0.1 to 0.35 and (b) a B X-ray ratio in the range of 0.75 to 0.98. Preferably the A X-ray ratio is in the range of 0.1 to 0.3, the B.sub.2 X-ray ratio is in the range of 0.75 to 0.98 and the B.sub.1 X-ray ratio is in the range of 0.1 to 0.32. The porous sheets are separators or diaphragms for electrolytic cells and the uses of such separators and cells in electrolysis processes, preferably in the electrolysis of brine, are described. Also known in the specification are a method for the manufacture of the porous sheets and a method for ascertaining which milled, sintered and leached porous sheets are more suitable for use in electrolytic processes.

Abstract: Microporous membrane materials suitable for use in electrolytic cells, such as cells for the electrolysis of brine to produce chlorine, are formed from a mixture of polytetrafluoroethylene, a particulate pore forming material and an organic fluorinated lubricant. Such materials are preferably formed into a sheet, which is rolled to a desired thickness, sintered and subjected to leaching out of the pore forming material.

Abstract: An improved apparatus for the electrolysis of aqueous solutions of ionizable chemical compounds is disclosed including specifically an apparatus for the production of chlorine and caustic containing low concentrations of sodium chloride by the electrolysis of brine which comprises electrolyzing brine solutions in a cell equipped with a cathode and an anode separated by a cation-active permselective diaphragm.

Abstract: Hydrophobic polymeric separators are made wettable to electrolytic cell fluids by a post-manufacturing process of treating with fluorinated surface-active agents. The application of a hydrophilic film of fluorosurfactant onto separator surfaces followed by drying renders the separator permanently wettable. The hydrophilic surfaces rendered inert by drying are reactivated in-situ after installation of the separator by contacting the separator surfaces with heated aqueous solution. The pre-installation process provides a convenient means for shipping fully manufactured separators and for their storage by users until actually needed. From an operational standpoint, the pre-installation process eliminates fouling of the cell with foam occurring with conventional in-situ wetting procedures.

Abstract: The invention disclosed herein relates to a polymeric microporous electrolytic cell separators for producing alkali metal hydroxide at high current efficiencies, said separator having:a. porosity of at least about 60%;b. thickness of between 8 and 130 mils;c. hysteresis of from 0.30 to 0.99 wherein hysteresis is defined as the ratio of the amount of mercury trapped within the pore structure of the separator after release of pressure to 1 psi compared to the amount of mercury present when first subjected to total impregnation by mercury at 50,000 psi, andd. distribution of pore sizes in a range between 0.004 and 34 microns wherein at least 85% of said pores have a diameter of between 0.12 and 33 microns and at least 60% of said pores have a diameter between 0.

Abstract: Microporous membrane materials suitable for electrolytic cell utilization are formed from the blend of particulate polytetrafluoroethylene, a dry pore forming particulate material, and an organic lubricant. The materials are milled and formed into a sheet, which is rolled to the desired thickness, sintered, and subjected to leaching of the pore forming materials.

Abstract: A method for electrolytically producing a purified alkali metal hydroxide solution by electrolyzing an alkali halide solution in a membrane cell is described. The membrane cell includes at least one buffer compartment separating an anolyte and a catholyte compartment. The barrier separating the anolyte and the buffer compartment is a porous or permeable membrane. The membrane separating the catholyte compartment and the buffer compartment is a cation-active, hydrocarbon, preferably non-porous, membrane. A minor amount of a compound selected from the group consisting of alkali metal sulfites, bisulfites, sulfides, oxalates, or mixtures thereof, is added to the electrolyte, preferably with the brine feed, to protect the membranes from hypohalites formed in the cell. Amounts of protective compounds between about 0.01 and about 2.0 percent by weight of electrolyte are found to be aptly suited to use.

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: This disclosure is directed to fluorocarbon polymers, polymeric membranes, and electrochemical cells and processes. The polymers and membranes are produced by radiation techniques to provide improved products. For example, .alpha.,.beta.,.beta.-trifluorostyrene in an inert organic solvent is grafted onto an inert film, such as tetrafluoroethylene-hexafluoropropylene copolymer, by irradiation, i.e. with Co-60 gamma radiation at a dose of several Mrad. The grafted film is then sulfonated, preferably in a chlorosulfonic acid bath. The resulting film is useful as a membrane or diaphragm in various electrochemical cells such as chlor-alkali or fuel cells.

Abstract: This disclosure is directed to fluorocarbon polymers, polymeric membranes, and electrochemical cells and processes. The polymers and membranes are produced by radiation techniques to provide improved products. For example, .alpha., .beta., .beta.-trifluorostyrene in an inert organic solvent is grafted onto an inert film, such as tetrafluoroethylene-hexafluoropropylene copolymer, by irradiation, i.e. with Co-60 gamma radiation at a dose of several Mrad. The grafted film is then sulfonated, preferably in a chlorosulfonic acid bath. The resulting film is useful as a membrane or diaphragm in various electrochemical cells such as chlor-alkali or fuel cells.

Abstract: An improved anode structure for a chlor-alkali type diaphragm cell wherein the anode is a porous, valve metal, e.g., titanium, anode having on one side a coating of a noble metal or noble metal oxide and on the uncoated side a membrane composed essentially of a cation-active permselective material which is substantially impervious to liquids and gases. The membrane covered surface is disposed spaced from but facing the cathode member.Anodes of this improved structure give minimum cell voltage and a surprisingly reduced consumption rate of the noble metal or oxide coating.

Abstract: An electrolytic cell, suitable for use in electrolyzing alkali metal halide brines, which comprises a cell body having an anode compartment containing an anode, a cathode compartment containing a cathode and at least two buffer compartments between said anode and cathode compartments, said anode compartment and said buffer compartments being separated from each other by a barrier which is substantially impervious to fluids and gases, selected from a hydrolyzed copolymer of tetrafluoroethylene and a sulfonated perfluorovinyl ether having the formula:FSO.sub.2 CF.sub.2 CF.sub.2 OCF(CF.sub.3)CF.sub.2 OCF=CF.sub.2said copolymer having an equivalent weight of from about 900 to 1600, and a sulfostyrenated perfluorinated ethylene propylene polymer and said cathode compartment being separated from the next adjacent buffer compartment by a porous 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: This disclosure is directed to fluorocarbon polymers, polymeric membranes, and electrochemical cells and processes. The polymers and membranes are produced by radiation techniques to provide improved products. For example, .alpha.,.beta.,.beta.-trifluorostyrene in an inert organic solvent is grafted onto an inert film, such as tetrafluoroethylene-hexafluoropropylene copolymer, by irradiation, i.e. with Co-60 gamma radiation at a dose of several Mrad. The grafted film is then sulfonated, preferably in a chlorosulfonic acid bath. The resulting film is useful as a membrane or diaphragm in various electrochemical cells such as chlor-alkali or fuel cells.

Abstract: An electrode, for use in electrolytic processes, comprises a valve metal substrate, such as titanium, a coating thereon of conductive tin oxide, and an outer coating of a noble metal or noble metal oxide. The electrode is particularly adapted to use in a chlorate cell wherein an aqueous alkali metal chloride solution is electrolyzed to produce an alkali metal chlorate.