Abstract: An increasing problem with the pulping chemical recovery system, is the presence of chloride and potassium in the recovery boiler. Chloride and potassium increase inter alia the stickiness of carryover deposits and dust particles to the recovery boiler tubes, which accelerate fouling, corrosion and plugging of the recovery boiler. As the environmental legislation becomes more stringent, the degree of system closure increases. The present invention relates to a process by which the collected precipitator dust is leached, at a temperature exceeding 50.degree. C., for a residence time sufficient to get a chloride and potassium enriched leach solution and to remove at least a part of the content of metal ions in a solid phase. Said leach solution is electrochemically treated, preferably in an electrodialysis cell, in order to remove at least a part of the chloride and potassium therein. By the present process, the problem of sticky deposits in the recovery boiler can be substantially reduced.

Abstract: An apparatus for producing deionized water consisting essentially of an electrodialyzer having cation exchange membranes and anion exchange membranes alternately arranged between a cathode and an anode to form demineralizing compartments and concentrating compartments, and ion exchangers accommodated in the demineralizing compartments, wherein a pressure of from 0.1 to 20 kg/cm.sup.2 is exerted between the ion exchangers accommodated in the demineralizing compartments and the cation exchange membranes and anion exchange membranes defining the demineralizing compartments.

Abstract: Improved electrodialysis (ED) stacks are disclosed having one or more components selected from the group:a) cation exchange membranes having ion exchange groups predominantly sulfonic acid groups and a minor amount of weakly acidic and/or weakly basic groups or membranes which are selective to monovalent cations and simultaneously therewith, cation exchange granules selective to monovalent cations as packing in the dilute compartments;b) anion exchange membranes having as ion exchange groups only quaternary ammonium and/or quaternary phosphonium groups and substantially no primary, secondary and/or tertiary amine and/or phosphine groups or membranes which are selective to monovalent anions simultaneously therewith, anion exchange granules selective to monovalent anions as packing in the dilute compartments;c) as packing in the dilute compartment, anion exchange granules which are selective to monovalent anions, or cation exchange granules which are selective to monovalent cations, or cation exchange granules

Abstract: An improved electrodeionization apparatus and method are provided. The electrodeionization apparatus includes an ion-concentrating compartment, an ion-depleting compartment, and electrolyte compartments, wherein alternating layers of anion exchange resins and cation exchange resins are positioned in the ion-depleting compartment, and the anion exchange resins comprise Type II anion resins. The incorporation of Type II anion material, alone or with Type I anion material, in anion permeable membranes and/or resins improves the electric current distribution, degree of resin regeneration, and deionization performance.

Abstract: A process of demineralizing a liquid containing organic matter and inorganic salts in solution, in which the treatment of the liquid comprises the following steps:the liquid is percolated over a strong cationic ion exchange resin for monovalent ions;both a batch of liquid from the preceding step and a brine for receiving ions from that liquid are caused to circulate in loops through at least one "two-compartment" electrodialyzer comprising a plurality of anionic membranes interposed between a plurality of cationic membranes; andthe brine whose salt concentration lies in the range 90 grams per liter (g/l) to 110 g/l is used to regenerate the ion exchange resin.

Abstract: This invention is related to a process for producing pulp from a cellulosic starting material, wherein an aqueous process effluent is purified from metal impurity cations. This process comprises that the effluent is purified by an electro-chemical membrane treatment in an electrochemical membrane device comprising a unit cell through which an electric current is passed between an anode side and a cathode side of said cell, said cell comprising at least two ion permeable membranes forming between them at least one compartment, said effluent being fed into an effluent feed compartment in said cell, in which the effluent is purified by removing with the electric current metal impurity cations from the effluent through a cation selective membrane on the cathode side of said compartment, and withdrawing from said compartment the purified effluent. The purified effluent may be recirculated to the pulp mill process, e.g. as washing water.

Abstract: A method of manufacturing an apparatus for the electrodeionization of a fluid includes determining the flow rate of the fluid to be deionized, its initial concentration of ionic impurities, a desired post-processing concentration of ionic impurities and appropriately selecting the number of diluting compartments for use in the apparatus and the electrical current to be applied between the anode and cathode in the apparatus and manufacturing the apparatus accordingly.

Abstract: A process for treating effluent from a flue-gas desulfurization system wherein the resulting gypsum is removed, comprises filtering the gypsum and fly ash free effluent by a filter, transferring the filtrate to an electrodialyzer wherein cation-exchange membranes and univalent anion-exchange membranes are alternately set up, concentrating chlorine ions in the solution therein by dialysis, further concentrating the solution by evaporation in an evaporator, kneading the concentrated solution with cement or a mixture of cement and coal ash to a solid matter with no harm, and thereafter abandoning for landfill; and an apparatus for treating effluent from a flue-gas desulfurization system, comprising a filter for filtering the effluent to a turbidity low enough for treatment by an electrodialyzer wherein the effluent is to be separated into concentrated and dilute solutions, the electrodialyzer equipped with an alternate arrangement of cation- and anion-exchange membranes, with concentration and dilution compartme

Abstract: A process for the preparation of ascorbic acid starting from an ascorbate is characterized in that an ascorbate, e.g. sodium ascorbate, dissolved in water is decomposed under the influence of an electric field by means of ion-selective membranes into ascorbate ions and cations and the latter are separated spatially from one another and then, as a result of simultaneous generation of protons and hydroxide ions, the ascorbic acid is prepared from the liberated ascorbate ions and protons and, spatially separated therefrom, the corresponding hydroxide, e.g. sodium hydroxide, is also prepared from the cations and hydroxide ions.

Abstract: Improved electrodialysis (ED) stacks are disclosed having one or more components selected from the group:a) cation exchange membranes having ion exchange groups predominantly sulfonic acid groups and a minor amount of weakly acidic and/or weakly basic groups or membranes which are selective to monovalent cations and simultaneously therewith, cation exchange granules selective to monovalent cations as packing in the dilute compartments;b) anion exchange membranes having as ion exchange groups only quaternary ammonium and/or quaternary phosphonium groups and substantially no primary, secondary and/or tertiary amine and/or phosphine groups or membranes which are selective to monovalent anions simultaneously therewith, anion exchange granules selective to monovalent anions as packing in the dilute compartments;c) as packing in the dilute compartment, anion exchange granules which are selective to monovalent anions, or cation exchange granules which are selective to monovalent cations, or cation exchange granules

Abstract: A process for the preparation of keto compounds from the associated alkali metal salts, in which process protonation is carried out by electrodialysis in a nonaqueous medium without the addition of acid which is foreign to the system, and the keto compounds are thereby liberated.

Abstract: Salt-free aqueous solutions of bisaminoxyalkanes (I) are prepared by a process in whicha) a dihaloalkane (II) is converted with a ketoxime (III) in an aqueous solution of a strong mineral base into the alkylene bisoxime ether (IV),b) the alkylene bisoxime ether (IV) is cleaved with a strong mineral acid and water to give the ketone and the salt of the mineral acid with the bisaminoxyalkane (I), and the ketone is separated off in a conventional manner,c) an alkali metal hydroxide is added to the remaining aqueous solution to liberate the bisaminoxyalkane (I) andd) the ionic components are removed from the resulting aqueous solution by electrodialysis.

Abstract: In order to reduce releasing of neutral salts comprising monovalent ions contained in industrial waste effluent to the environment, the waste effluent to be treated is supplied into a prepositive electrodialysis cell comprising ion exchange membranes which transfer monovalent ions selectively for concentrating the salts, concentrated stream is supplied into an electrolytic dialysis cell for separating and recovering acids and bases, subsequently diluted stream is circulated as supplying stream to the prepositive electrodialysis cell, the diluted stream in said prepositive electrodialysis cell is subsequently supplied to and desalted by one or plural electrodialysis cells combined in series, the diluted stream after the desalination is released to the environment, and the concentrated stream is merged to the supplying stream to the prepositive electrodialysis cell.

Abstract: A process for the recovery of alkali metal hydroxide and acid from the alkali metal salts of monovalent anions which are mixed with the alkali metal salts of multivalent anions employs a water-splitting system composed of bipolar membranes in conjunction with ion-selective membranes; a two-compartment cell employs monovalent anion-selective membranes to define salt/base and acid compartments with the bipolar membranes, and a three-compartment cell employs, monovalent anion-selective and cation-selective membranes to define with the bipolar membranes, acid, salt and base compartments; the process has particular applicability to the conversion of the sodium/potassium chloride portion of the Electrostatic Precipitator (ESP) Catch of the recovery boiler of coastal and/or closed-cycle kraft pulp mills, a mixture of mostly sodium/potassium sulphate and chloride, into sodium/potassium hydroxide and hydrochloric acid; the remaining sodium/potassium sulphate solution, depleted in chloride, can thus be used as sodium/s

Abstract: The invention relates to a process for treating a low-concentrated aqueous feed solution which includes at least one aqueous process stream from a pulp mill. The process includes concentrating the feed solution by evaporation to form an evaporation concentrate, and subjecting at least a part of the concentrate to a first electrodialysis treatment, thereby forming a first electrodialysis concentrate containing salt removed from the evaporation concentrate and at least one diluate depleted in the salt. The invention also relates to a plant for carrying out the above process.

Abstract: A desalting method of a silver halide emulsion is disclosed, comprising removing soluble salts from the silver halide emulsion by electrodialysis, wherein said electrodialysis is carried out at a pH within a range of .+-.0.5 of an isoelectric point of a gelatin contained in the silver halide emulsion. Furthermore, by adding a salt during the course of the electrodialysis, the concentration of the emulsion is accomplished concurrently with desalting thereof.

Abstract: A process for separating monovalent ions from a sodium-bearing radioactive waste stream which comprises contacting the sodium-bearing radioactive waste stream against at least one ion exchange membrane having permselectivity for monovalent ions wherein the monovalent ions permeate or diffuse across the ion exchange membrane to form a permeate of a monovalent ion-enriched stream and wherein a retentate is formed from the sodium-bearing radioactive waste stream which is substantially depleted of monovalent ions.