Other

Learonal, Inc.

Daniel J Vaughan

Fred I Nobel

A method is provided for removal of ferrous ions from a tin-plating electrolyte containing stannous ions in a multi-compartmented electrochemical cell equipped to convert the ferrous and stannous ions to insoluble hydroxides. The hydroxides, in an essentially air-oxygen free environment, are separated by selectively dissolving the ferrous hydroxide in an acidic solution and the undissolved stannous hydroxide in the tin plating electrolyte.

Process for removing iron from tin-plating electrolytes

An electrode composed of a current element and a fiber element suitable for operation at low voltage and high amperage is disclosed.

Electrode system and use in electrolytic processes

Process and equipment for manufacturing salts of metals, particularly nickel hypophosphite, are disclosed.

Method for manufacturing salts of metals

Methods for preparing hypophosphorous acid are disclosed comprising contacting an insoluble anode with an aqueous solution of hypophosphite anions and applying a current through the insoluble anode to a cathode in electrical contact with the aqueous solution to generate H+ ions in the aqueous solution thereby forming a hypophosphorous acid solution.

Electrolytic production of hypophosphorous acid

An electrochemical process and equipment for preparing iodides, e.g. hydriodic acid (HI), iodide salts and other iodide compounds, substantially free of iodine, are disclosed.

Method and apparatus for manufacturing iodine-free iodides

Process and equipment for reforming and maintaining the chemistry of an electroless metal bath, particularly an electroless nickel bath is disclosed.

Process and equipment for reforming and maintaining electroless metal

Oxidation and reduction reactions are carried out in a continuous aqueous solution having an acidic part and an alkaline part formed by electrolysis and electrodialysis of an acidic electrolyte separated by a cation permeable membrane from an alkaline electrolyte containing a soluble anion of an acid whereby hydrogen ions are electrotransported from an acidic electrolyte through a cation permeable membrane into said alkaline electrolyte to form the acidic part. Reactions are carried out in the acidic or alkaline part or simultaneously or successively in the acidic and alkaline parts by adding reactants to said alkaline electrolyte and passing electricity through said electrolysis and electrodialytic process. Chromium.sup.+6 in the alkaline part is reduced to chromium.sup.+3 in the acidic part by addition of sulfur dioxide to the alkaline part and the chromium.sup.+3 is precipitated by hydroxyl ions in the alkaline part.

Electrodialytic oxydation-reduction of metals

Complexes and salts of metal cations in aqueous solutions are electrodialytically converted into a solution of acids substantially free of metal cations and insoluble metal hydroxides. Metal cations are insolubilized by hydroxyl ions formed in a catholyte while anions are electrotransported from the catholyte and converted into a solution of acids by hydrogen ions formed in an anolyte of an electrodialytic process. The conversion process is carried out electrically without the electrotransport of metal cations and is especially useful for reforming solutions of acids that form complexes when etching and finishing metal surfaces.

Electrodialytic conversion of complexes and salts of metal cations

Complexes and salts of metal cations and acid anions are electrodialytically converted into insoluble hydroxides of the metal cations and acids of the anions. The conversion is effected without the electrotransport of metal cations by insolubilizing the metal cations with hydroxyl ions formed in a catholyte separated by a cation permeable membrane from an anolyte and converting anions of alkali salts formed in the catholyte to acids in the anolyte. The process comprises (a) feeding a solution of a metal complex or salt to a catholyte containing alkali cations; (b) forming hydroxyl ions in the catholyte to form insoluble metal hydroxides and alkali salts of acid anions; (c) separating the insoluble hydroxide from the catholyte; (d) feeding the separated catholyte to the anolyte whereby alkali cations are electrotransported from the anolyte to the catholyte.

An alkali hydroxide solution of a metal hydroxide or metallic oxide acidic is separated into a solid metal hydroxide or metallic oxide acidic and a solution of alkali hydroxide by feeding the alkali solution to an electrolyte comprising a soluble anion of an acid and controlling the pH of the electrolyte to insolubilize a metal hydroxide or metallic oxide acidic by electrotransporting alkali cations from the electrolyte through a cation permeable membrane into a catholyte and converting the alkali cations to a solution of alkali hydroxide. Sodium hydroxide etchants of aluminum containing sodium aluminate are continuously converted to aluminum hydroxide and a solution of sodium hydroxide.

Restoration of alkali hydroxide etchants of aluminum

A solution, sol or colloidal dispersion of a substantially water insoluble metal hydroxide or acid and an alkali metal hydroxide are electrodialytically converted to a solid substantially water insoluble metal hydroxide or acid and a solution of the alkali metal hydroxide substantially free of the water insoluble metal hydroxide or acid. The conversion is effected by electrodialysis and electrotransport of an alkali metal cation from the solution, sol or dispersion through a cation permeable membrane into an aqueous alkali hydroxide solution and by using a water soluble anion of an acid to vary pH of the solution sol or dispersion to insolubilize the water insoluble metal hydroxide or acid. Sodium hydroxide etchants of aluminum are continously converted to solid aluminum hydroxide and aqueous sodium hydroxide free of aluminum hydroxide.

Electrodialytic process for restoring sodium hydroxide etchants for

A multivalent metal hydroxide is separated as a solid from an alkali hydroxide or from another multivalent metal hydroxide in an electrodialytic cell. The separation process is regulated by varying the pH or concentration of alkali hydroxide in a feed compartment electrolyte by matching the rate alkali cations are fed and removed from the electrolyte. As a result, one multivalent metal cation separates as a solid in the feed electrolyte or one multivalent cation separates as a solid and one multivalent cation is ionically mobile and electrotransportable from the electrolyte. This electrodialytic method can be used to continuously regenerate sodium hydroxide etchants containing dissolved aluminum, when the dissolved aluminum is removed from the etchant as a solid and the sodium hydroxide is returned as a solution for etching.

Electrodialytic recovery process

Multivalent metal cations in aqueous solution are electrotransported efficiently and with high capacity through cation permeable membranes into an aqueous solution containing a sulfonate ion which makes possible a simple electrodialytic process for conversion of all salts of multivalent metal cations into the respective acids or halogens of the anions of the salts and into water soluble salts or water insoluble salts or ionically immobile compounds of the multivalent metal cations. The use of a sulfonate ion the acid of which in a one normal solution would have a pH no greater than three (3) prevents fouling of the membrane and makes electrodialytic conversion of especially salts of barium, strontium, calcium and lead simple, efficient and with high capacity without the formation of undesirable products of electrolysis at the cell anode or cathode.

Electrodialytic conversion of multivalent metal salts using sulfonate

The ends of flexible plastic tubes, particularly of relatively thin thickness, are closed with a cylindrical header or end plug over which an end of the plastic tube is fitted. A fluids connection between the wall of the plastic tube and the cylindrical header or plug is made by press fitting over the connection area a plastic ring smaller in diameter than the outside diameter of the plastic tube within the elastic limit of the plastic ring. Preferably the header and/or end plug have circumferential grooves or depressions into which groove or depression the wall of the tube is fitted or depressed, preferably by multi-turns of plastic threads. For corrosive and oxidizing environments the header, plug, plastic tube, sealing rings and depressing thread are composed of perfluorocarbon polymers.

End closure for flexible plastic tubes

An electrolytic purification process useful for contaminated solutions of oxygen-sensitive organic dyes and other such sensitive organic materials and metal chelates and complexes of organic materials involves applying an electrical potential to said solutions in an intermediate or feed compartment separated by cation permeable membranes from an anolyte compartment having an anode and an acidic aqueous anolyte and from a catholyte compartment having a cathode and an aqueous catholyte whereby the impressed electrical current causes metal cations to be electrotransported through the cation permeable membrane into the catholyte and the solution of oxygen- or hydrogen-sensitive organic material is purified without exposure to the anode or oxygen formed at the anode or to the cathode or hydrogen formed in the catholyte compartment. A special embodiment comprises treating solutions of oxygen- or hydrogen-sensitive organic materials first with a salt of a multivalent metal cation to insolubilize such organic materials, separating the insolubilized organic material from unwanted substances such as large volumes of water found in dilute solutions of the desired organic material or other substances encountered in the solutions, dissolving the separated insolubilized organic material in an acidic aqueous solution and removing the multivalent metal cations by electrotransport thereof through a cation permeable membrane into a catholyte as described in the above described electrolytic purification process.

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Wilmington, DE, United States of America

Daniel J Vaughan