Hooker Chemicals & Plastics Corporation

Occidental Chemical Corporation

Rai Research Corporation

Edward H Cook, Jr

Christine A Lazarz

Vincent F D'Agostino

Joseph Y Lee

Alvin T Emery

Jeffrey D Eng

Arthur C Schulz

Wilfredo E Figueras

Gerald R Marks

Lesleigh V Scripa

Eng-Pi Chang

Dirk Pouli

Ursula I Keller

Krishnan Viswanathan

Bernardus Johannes Mentz

Blaine O Schoepfle

Steven M Beck

Daniel T Tokawa

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.

Phosphorus recovery from phosphorus-containing pond sludge

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 0.1 micron diameter pores in the microporous sheet helps to prevent the cell from 'going high voltage' during operation and the presence of one to ten micron diameter pores improves diaphragm action while still maintaining a low resistance thereof. Also disclosed are: a diaphragm made from a portion of such sheet material; an electrolytic cell including such a diaphragm; a method of electrolyzing brine, utilizing such a cell, and a method for testing of such sheets so as to determine suitability for use thereof as stable low voltage diaphragms in electrolytic cells.

Method of electrolyzing brine with stable low voltage microporous

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.

Method of increasing useful life expectancy of microporous separators

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.

Process for forming a porous polyfluoroalkylene sheet useful for

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 0.1 micron diameter pores in the microporous sheet helps to prevent the cell from 'going high voltage' during operation and the presence of one to ten micron diameter pores improves diaphragm action while still maintaining a low resistance thereof. Also disclosed are: a diaphragm made from a portion of such sheet material; an electrolytic cell including such a diaphragm; a method of electrolyzing brine, utilizing such a cell; and a method for testing of such sheets so as to determine suitability for use thereof as stable low voltage diaphragms in electrolytic cells.

Stable low voltage microporous diaphragm for electrolytic cells

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.

Porous polyfluoroalkylene sheet useful for separating anolyte from

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.

Microporous membrane materials

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.

Electrolysis apparatus

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.

Processes of wetting hydrophobic fluoropolymer separators

The invention disclosed herein relates to a polymeric microporous electrolytic cell separators for producing alkali metal hydroxide at high current efficiencies, said separator having:

Polymeric microporous separators for use in electrolytic processes and

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.

Method for forming microporous membrane materials

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.

Method of electrolytically producing a purified alkali metal hydroxide

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.

Electrolytic cell utilizing pretreated semi-permeable membranes

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.

Trifluorostyrene sulfonic acid membranes

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.

Growing community of inventors

Lewiston, NY, United States of America

Edward H Cook, Jr