Abstract: Method for limiting growth of KDP-type crystals with a long seed where an upper and a lower ends of the long seed crystal are respectively limited by an upper baffle plate and a lower tray to restrain growth of a pyramidal surface and allow only four prismatic surfaces in [100] and [010] directions to grow. Finally grown crystal contains no pyramid-prism interface that severely restricts quality of optical element, and all cut optical elements have high optical quality. As four prismatic surfaces are subjected to highly similar growing environment and grow simultaneously, all optical elements cut therefrom have high optical uniformity. Due to uniqueness of a cutting angle of a KDP crystal frequency-tripled element, high cutting efficiency is achieved in the element, and an area of a maximum frequency-tripled element that may be cut is known in advance according to a horizontal size of the grown crystal.

Abstract: The present invention relates to a method for manufacturing lithium hydroxide and lithium carbonate, and a device therefor.

Abstract: The invention relates to an absorption refrigeration machine (10) that includes an evaporator (12) and an absorber (18) and is characterized in that the evaporator (12) comprises at least one evaporating unit (12?) having a coolant channel (26), through which the coolant (16) flows and which is delimited at least in part by a heat-conducting, vapor- and liquid-tight wall (24), and having at least one refrigerant channel (28) that adjoins the heat-conducting wall (24), is loaded with the refrigerant (14), and is separated from a vapor chamber (32) by a vapor-permeable, liquid-tight membrane wall (30) on the side of the refrigerant channel opposite the heat-conducting wall (24), and in that the absorber (18) comprises an absorption unit (18?) having a cooling-medium channel, through which a cooling medium (34) flows and which is delimited at least in part by a heat-conducting, vapor- and liquid-tight wall (36), and having an absorption channel (40) which adjoins the heat-conducting wall and to which the concent

Abstract: To prevent biological fouling in an electrodialysis device, an electrodialysis device including a membrane electrolysis stack are created. Every membrane electrolysis stack comprises membranes stacked on top of each other and respectively dilute and concentrate compartments arranged therebetween, at least one first and at least one second membrane alternating in succession in the membrane electrolysis stack. At least one first membrane is selected from a group comprising an anion exchange membrane and a bipolar membrane, and at least one second membrane is selected from a group comprising a monoselective anion exchange membrane, a monoselective cation exchange membrane and a proton-selective exchange membrane, with the proviso that the second membranes are respectively selected independently of each other and that at least one first membrane in the membrane electrolysis stack is a bipolar membrane.

Abstract: A method and a system for process parameter control of a liquid composition in a reverse electro-enhanced dialysis (REED) system comprising at least two Reverse Electro-Enhanced Dialysis (REED) membrane stacks, wherein the direction of the electric field within any one membrane stack is reversed at asynchronical intervals of time relative to the current reversals for any other membrane stack.

Abstract: A process for producing ultrapure water, in which a stream of water is purified in a reverse osmosis device, wherein the water stream is subject to pretreatment including splitting the water stream into at least two partial streams, partial exchange of cations present in at least one of the partial streams for H+ ions by a cation exchanger operated in the H+ mode, and complete exchange of the anions present in at least one further of the partial streams for OH? ions by a softener operative in parallel to the cation exchanger, and treating the partial streams treated by the cation exchanger and the softener by at least one anion exchanger operating in the OH? mode, and wherein the water stream obtained from the pretreatment is fed into the reverse osmosis device.

Abstract: A method and a system for process parameter control of a liquid composition in a reverse electro-enhanced dialysis (REED) system comprising at least two Reverse Electro-Enhanced Dialysis (REED) membrane stacks, wherein the direction of the electric field within any one membrane stack is reversed at asynchronical intervals of time relative to the current reversals for any other membrane stack.

Abstract: A treatment system provides treated or softened water to a point of use by removing at least a portion of any undesirable species contained in water from a water source. The treatment system can be operated to reduce the likelihood of formation of any scale that can be generated during normal operation of an electrochemical device. The formation of scale in the treatment system, including its wetted components, may be inhibited by reversing or substituting the flowing liquid having hardness-causing species with another liquid having a low tendency to produce scale, such as a low LSI water. Various arrangements of components in the treatment system can be flushed by directing the valves and the pumps of the system to displace liquid having hardness-causing species with a liquid that has little or no tendency to form scale.

Abstract: The invention is directed to a process for the removal of ammonia from an ammonia-containing gas stream by treating the ammonia in the ammonia-containing gas stream with an acid, during which treatment an aqueous stream comprising an ammonium salt, wherein the aqueous stream comprising the ammonium salt is treated with electrodialysis, whereby the acid is recovered and an aqueous stream comprising an ammonium hydroxide salt is formed.

Abstract: An electrochemical separation system may be modular and may include at least a first modular unit and a second modular unit. Each modular unit may include a cell stack and a frame. The frame may include a manifold system. A flow distribution system in the frame may enhance current efficiency. Spacers positioned between modular units may also enhance current efficiency of the system.

Abstract: A continuous electrochemical pump comprising a water generator compartment, an anode compartment on one side of said generator compartment, a cation exchange barrier, separating the generator compartment from the anode compartment, it first electrode in electrical communication with the anode compartment, a cathode compartment adjacent the generator chamber, an anion exchange barrier, separating the generation compartment from the cathode compartment, and a second electrode in electrical communication with the cathode compartment. Use of the pump as a sample concentrator. A feedback loop for the pump. A reservoir, with or without an intermediate piston, on the output side of the pump.

Abstract: A desalination plant, includes a sea water intake, a desalination unit having a reverse osmosis or a thermal desalination unit, a fresh water outlet and a brine outlet. The plant also includes a salinity gradient power unit having a brine inlet, a seawater inlet and a mixed water outlet. The brine outlet is connected to the brine inlet and the salinity gradient power unit is arranged to generate an electrical current. A solar power heater is between the brine outlet and the brine inlet. A method for reducing the power consumption of a desalination plant providing fresh water and brine from sea water, includes a first step of providing a salinity gradient power unit, a next step of feeding the salinity gradient power unit with brine from the desalination plant as high salinity feed and sea water as low salinity feed.

Abstract: Described herein are a method and system for desalinating saltwater using concentration difference energy. A “five stream” dialytic stack is described that can be used to desalinate saltwater at a relatively high recovery ratio. The dialytic stack may include, for example, one or more drive cells having a paired concentrate and a diluent-c chamber in ionic communication with a product chamber that is adjacent to an anion and a cation discharge chamber each filled with diluent-p. The drive cell applies a drive voltage across the product chamber, and when the drive voltage exceeds a desalination voltage of the product chamber, the saltwater in the product chamber is desalinated. The diluent-p may be at a lower ionic concentration than the diluent-c, which may be at a lower concentration than the concentrate.

Abstract: A method and apparatus for desalinating saltwater using concentration difference energy is disclosed. In order to desalinate saltwater that is contained within a product chamber, a drive cell is used to generate a drive voltage. The product chamber has a desalination voltage such that when a sufficient voltage is applied to the product chamber, anions and cations migrate out of the product chamber, thereby desalinating the water. The sufficient voltage, which includes the drive voltage and which is equal to or greater than the desalination voltage, is applied to the product chamber, consequently effecting desalination. Beneficially, concentration difference energy can be generated using a concentrated solution, which can be generated using, for example, solar energy.

Abstract: A continuous electrochemical pump comprising a water generator compartment, an anode compartment on one side of said generator compartment, a cation exchange barrier, separating the generator compartment from the anode compartment, a first electrode in electrical communication with the anode compartment, a cathode compartment adjacent the generator chamber, an anion exchange barrier, separating the generation compartment from the cathode compartment, and a second electrode in electrical communication with the cathode compartment. Use of the pump as a sample concentrator. A feedback loop for the pump. A reservoir, with or without an intermediate piston, on the output side of the pump.

Abstract: Desalination is carried out by a hybrid ion exchange-nanofiltration process in which ion exchange is followed by pressure-driven nanofiltration. Monovalent ions of sodium and chloride of saline water are exchanged for equivalent concentrations of poly-valent ions (for example, sodium ions for magnesium ions or chloride ions for sulfate ions) when passed through ion exchangers in the form of those poly-valent ions. The resultant solution has a lower osmotic pressure than the initial solution containing monovalent sodium and chloride ions, and requires less transmembrane pressure for membrane desalination compared to traditional reverse osmosis. The concentrated reject stream from the membrane process is used as regenerant for the exhausted ion exchanger, which has been converted to monovalent anionic or cationic form.

Abstract: The invention relates generally to processes for the production of high-basicity and ultra-high basicity polyaluminum chlorides including aluminum chlorohydrate. The processes can produce products of a wide range of basicities and are particularly useful in producing high basicity products. The process can produce a wide range of solution concentrations and are particularly useful in producing high solution concentrations. The processes described generate high purity products, which are free of by-product salt(s). The processes described herein can also be utilized to produce enhanced efficacy polyaluminum chlorides including aluminum chlorohydrate. When compared to conventional processes for manufacturing these compounds the processes disclosed herein are unique in so far as the disclosed processes do not require aluminum metal as a starting material. The products of the processes are suitable in applications including water purification, catalysts, and antiperspirants.

Abstract: This invention presents an ion exchange media including a plurality of cation exchange zones and anion exchange zones in flow paths that are contained in a substantially nonporous resin transport framework. During electrodeionization and other potential applications the ion exchange media of the invention prevents unfavorable water splitting at resin-membrane interfaces and encourages water splitting at resin-resin interfaces where the water splitting may be constructively used to regenerate the resin.

Abstract: An improved apparatus and operating method related thereto for deionizing water to produce substantially pure water using electric field and ion exchange materials are disclosed, including embodiments incorporating one or more of the novel features of brine and electrode streams flowing in a direction counter-current to the stream being deionized, a filling of the brine stream with stratified ion exchange materials, a stream mixing feature for mixing the stream being deionized, a gas removal feature for removal of gases, a spiral-wound embodiment of an electrodialysis device according to the invention, and a method for determining the preferred operating current for electrodialysis systems according to this invention.

Abstract: In regenerating an electroless metal plating bath by electrodialysis, it has been found that the metal of the metal plating bath deposits in the electrolysis arrangement. To overcome this problem, an improvement to prior art regenerating devices is suggested, said improvement consisting in providing main cation exchangers for removing ions of this metal from a concentrate fluid. The main cation exchangers are coupled to the concentrate compartments of the electrolysis arrangement in such a manner that the concentrate fluid flowing through the concentrate compartments is allowed to pass through the main cation exchangers and to be recirculated back into the concentrate compartments.

Abstract: A method for selectively removing hydrogen sulfide and carbon dioxide from sour gas by reacting the hydrogen sulfide and carbon dioxide in the sour gas with sodium hydroxide is disclosed. Also disclosed is a process for the production of a salt product from a sour gas stream. The reaction with sodium hydroxide creates a scrubber solution comprising water, hydrocarbons, contaminants and salts. The scrubber solution may be oxidized, filtered and can then be subjected to electrodialysis. Ammonia is introduced into the acid compartments of the cell. Sodium hydroxide and a salt product comprising ammonium sulfate or ammonium thiosulfate with ammonium bicarbonate, ammonium carbonate, ammonium carbamate may be produced. The regenerated sodium hydroxide may be used to sweeten further sour gas. The salt product may be used as a fertilizer.

Abstract: The invention includes novel anion exchange membranes formed by in situ polymerization of at least one monomer, polymer or copolymer on a woven support membrane and their methods of formation. The woven support membrane is preferably a woven PVC membrane. The invention also includes novel cation exchange membranes with or without woven support membranes and their methods of formation. The invention encompasses a process for using the membranes in electrodialysis of ionic solutions and in particular industrial effluents or brackish water or seawater. The electrodialysis process need not include a step to remove excess ions prior to electrodialysis and produces less waste by-product and/or by-products which can be recycled.

Abstract: An integrated treatment system using electrodialysis and pressure-driven membranes for deionizing and decontaminating liquids to a near-pure quality for use or reuse in industrial or municipal operations. The integrated system includes steps of pre-filtering contaminated feed liquids blending the filtered liquids in preparation for treating the mixed liquids in parallel or sequential treatment steps utilizing nanofiltration or reverse osmosis, proceeded by or followed by an integrated electrodialysis treatment. A control means selectively directs mixed liquids to each of the treatment units for treatment in parallel or in series depending on the conductivity and residual contaminants in the mixed liquids. In comparison with nanofiltration or reverse osmosis only systems, or electrodialysis only systems, the integrated system provides improved efficiencies for treatment, requires less energy to operate, and reduces maintenance and capital costs.

Abstract: A process and system for purifying water is disclosed. For example, in one embodiment, the process may be used to remove a divalent salt, such as calcium sulfate, from a water source in order to prevent the divalent salt from precipitating during the process. The water source, for instance, may be fed to an ion separating device, such as an electrodialysis device. In the electrodialysis device, an ion exchange takes place between the divalent salt and another salt, such as a monovalent salt to produce two concentrated salt streams that contain salts having greater solubility in water than the divalent salt. In one embodiment, the two salt streams that are produced may then be combined to precipitate the divalent salt in a controlled manner. During the process, various other components contained within the water feed stream may also be removed from the stream and converted into useful products. In one particular embodiment, the process is configured to receive a byproduct stream from a reverse osmosis process.

Abstract: A releaseable membrane structure for producing a free membrane containing a substrate, a release stratum on the substrate and a membrane stratum on the release stratum. The release stratum and the membrane stratum contain oppositely-charged polyelectrolytes that are associated. The oppositely-charged polyelectrolytes of the release stratum are selected to dissociate upon application of stimulus whereas those of the membrane stratum are selected to remain associated upon application of the stimulus. Thus, when the stimulus is applied the polyelectrolytes in release stratum dissociate and the membrane stratum is released from the substrate and is a free membrane.

Abstract: Filter or filter-element designated for Modified Electro-Dialysis (MED) purposes characterized in that the filter or filter-element comprises a porous, ceramic, mainly uniform material with functional, preferably ion selective groups grafted onto the inner, porous surface of the ceramic body. The outer surface of the filter or filter-element may be completely or partly covered by layers of porous, ceramic membranes with a pore size of less than 1 ?m and thickness less than 1 mm, and/or anion, cation or bipolar groups or membranes. The thickness of the filter-element is larger than 1 mm and has pores of size larger than 1 ?m. The invention also relates to a method for the manufacture of such a filter either continuously by tape-casting, extruding, rolling or calendaring or single-bodied by casting, pressing or forging, of a paste containing a non-conductive, ceramic material.

Abstract: An aqueous zinc nitrite solution which contains substantially no calcium (Ca) ions is provided, in which, in terms of the aqueous zinc nitrite [Zn(NO2)2] solution having an NO2 concentration of 10% by weight, the sodium (Na) ion concentration is 200 to 2000 ppm and the sulfate (SO4) ion concentration is 20 ppm or less in the solution. The aqueous zinc nitrite solution can be prepared by providing a zinc compound and an alkali nitrite as raw materials and subjecting the raw materials to electrolytic synthesis through a double decomposition reaction using an ion-exchange membrane as a diaphragm. As the aqueous zinc nitrite solution is provided, an extremely efficient metal surface treatment is made possible which has a reduced amount of sodium ions. In particular, it contains substantially no sulfate ions and no calcium ions.

Abstract: A process for preparing salts of methallylsulfonic acid in which the reaction mixture produced from the sulfonation is diluted with water and neutralized with a base.

Abstract: The invention includes novel anion exchange membranes formed by in situ polymerization of at least one monomer, polymer or copolymer on a woven support membrane and their methods of formation. The woven support membrane is preferably a woven PVC membrane. The invention also includes novel cation exchange membranes with or without woven support membranes and their methods of formation. The invention encompasses a process for using the membranes in electrodialysis of ionic solutions and in particular industrial effluents or brackish water or seawater. The electrodialysis process need not include a step to remove excess ions prior to electrodialysis and produces less waste by-product and/or by-products which can be recycled.

Abstract: Two concentration techniques, adsorption and electrodialysis, are combined to enrich lithium ions in brine from a level of several ppm to about 1.5%. At beginning brine is subjected to an adsorption, so that Li content is increased to 1200-1500 ppm, followed by two stages of electrodialysis in series to increase Li ions to about 1.5%. Li depleted solution from the second stage of electrodialysis having a Li content of 1200-1500 ppm is recycled to the first stage of electrodialysis as a feed. Li depleted water from the first stage of electrodialysis is subjected to a residue recovery electrodialysis to form a Li enriched solution of 1200-1500 ppm, which is also recycled to the first stage of electrodialysis as a feed. Li depleted solution from the residue recovery electrodialysis is recycled as a feed of the adsorption, so as to sufficiently recover Li ions from brine.

Abstract: An electrodialysis cell is operated in the presence of organic compounds that binds or chelates with the multivalent metals to form a metal chelating buffer. Among other things, this binding or chelating reduces power consumption, produces a stable cell operation, and avoids a fouling of the membranes while significantly improving membrane life, reliability, and operating costs. When a chelating agent is added to a salt solution containing multivalent cations, the chelating agent strongly binds with the cations, forming large size complexes. An ion exchange membrane retains these complexes within the compartment of the electrodialysis cell containing the feed solution. The multivalent cations is greatly inhibited from being transported across the cation exchange membrane, thus reducing the fouling of the cation membranes. Concurrently, the precipitation of the metals transported to the base loop is substantially abated.

Abstract: Two concentration techniques, adsorption and electrodialysis, are combined to enrich lithium ions in brine from a level of several ppm to about 1.5%. At beginning brine is subjected to an adsorption, so that Li content is increased to 1200-1500 ppm, followed by two stages of electrodialysis in series to increase Li ions to about 1.5%. Li depleted solution from the second stage of electrodialysis having a Li content of 1200-1500 ppm is recycled to the first stage of electrodialysis as a feed. Li depleted water from the first stage of electrodialysis is subjected to a residue recovery electrodialysis to form a Li enriched solution of 1200-1500 ppm, which is also recycled to the first stage of electrodialysis as a feed. Li depleted solution from the residue recovery electrodialysis is recycled as a feed of the adsorption, so as to sufficiently recover Li ions from brine.

Abstract: The present invention provides means for recovering and reusing useful component ions in electrolytic phosphate chemical treatment bath without subjecting them to waste water treatment. In the present invention, a phosphate chemical treatment bath which contains phosphate ions and phosphoric acid, metal ions that form a phosphate crystal to provide a film, metal ions that are reduced from cations in the solution to form a film as metals, and ions that are involved in the reaction of the above-mentioned phosphoric acid and various metal ions to form a film, but which does not substantially contain ions that are not involved in film formation, is used as the phosphate chemical treatment bath.

Abstract: The invention provides a novel solution isoelectric focusing device and method that can reproducibly fractionate charged molecules into well-defined pools. This approach can be applied to mixtures of charged molecules, such as eukaryotic proteome samples where reproducible resolution and quantitation of greater than 10,000 protein components is feasible.

Abstract: An electrodialysis method and apparatus include a source of concentrate fluid, a source of dilute fluid, a collector of treated concentrate fluid, a collector of dilute fluid, an anode and a cathode. A plurality of generally planar spacers are interleaved with a plurality of membranes to define a plurality of cells providing electrically conductive fluid connection between the anode and the cathode. Each of the spacers comprises a gasket that defines a first aperture and a second aperture. Each of said first and second apertures define an independent cell between interleaved membranes. The symmetrical, multiple split cell spacer configuration channels fluid flow through two or more narrow and elongated paths. The split cell arrangement allows for operation of the stack in parallel or in series.

Abstract: An electrodeionization apparatus and method of use includes an expanded conductive mesh electrode. The expanded conductive mesh electrode may be formed from any conductive material that is dimensionally stable and may be coated with conductive coating. The expanded conductive mesh electrodes typically have a diamond-shaped pattern of any size that provides support for an adjacent ion-permeable membrane while allowing an electrode or fluid stream to flow through. The conductive mesh electrode may also be placed against an endblock having fluid channels. These channels may be serpentine or parallel channels, which allow fluid flow to wash away any accumulation. The electrodeionization apparatus may have a protective ion-permeable membrane adjacent the electrode. The electrodeionization apparatus may also have a spacer, such as a fabric, a screen or a mesh, positioned adjacent the electrode.

Abstract: The present invention provides a cation exchange membrane which has excellent durability, a high limiting current density, a low direct current membrane resistance and excellent selectivity to monovalent cations. In the present invention, a cation exchange membrane excellent in selective permeability to monovalent cations is produced by bringing high molecular cations into contact with a surface of a cation exchange membrane in the presence of anions of an oxyacid or anions of an organic sulfonic acid.

Abstract: An electrodeionization apparatus and method of use includes an expanded conductive mesh electrode. The expanded conductive mesh electrode may be formed from any conductive material that is dimensionally stable and may be coated with conductive coating suitable for use in anode or cathode service. The expanded conductive mesh electrodes are formed by slitting a sheet of metal and pulling its sides in a direction perpendicular to the slits. The fabricated mesh may be flattened after stretching. The expanded conductive mesh electrodes typically have a diamond-shaped pattern of any size that provides support for an adjacent ion-permeable membrane while allowing an electrode or fluid stream to flow through. The mesh size typically has a long-wise dimension and a short-wise dimension. The conductive mesh electrode may also be placed against an endblock having fluid channels. These channels may be serpentine or parallel channels, which allow fluid flow to wash away any accumulation.

Abstract: Process for the manufacture of alkali metal hydroxide, according to which an electrodialysis cell containing three compartments is used, an aqueous alkali metal halide solution is circulated in a saline compartment of the cell, delimited between an anionic membrane and a cationic membrane, an alkali metal halide is introduced into an acidic compartment of the cell, delimited between the anionic membrane and a cationic face of a bipolar membrane and an aqueous alkali metal hydroxide solution is extracted from an alkaline compartment of the cell, delimited between the cationic membrane and an anionic face of the bipolar membrane.

Abstract: A process for preparing salts of methallylsulfonic acid in which the reaction mixture produced from the sulfonation is diluted with water and neutralized with a base.

Abstract: An electrodialysis treatment system utilizing a plurality of disparate layers of an electrodialysis cell stack for separation of components in liquid mixtures. The system for electrodialysis treatment for purification and deionizing liquids includes providing an operation of pretreatment by filtration for removal of inorganic and organic contaminants and generating a filtrate effluent. An adsorbing operation for adsorbing organic contaminants from the filtrate effluent of the pretreatment operation is provided by utilizing activated carbon adsorption and generating a liquid fraction. A deionizing operation for continuously purifying the liquid fraction is provided by utilizing an electrodialysis stack having a plurality of ion exchange membranes and separating gaskets for selectively removing contaminant ions from the liquid fraction of the adsorbing operation.

Abstract: An ion-exchange membrane having excellent resistance against organic fouling by high molecular weight organic ions etc. and showing low electric resistance is provided. Said ion-exchange membrane is characterized by that a polyether compound containing polyalkylene glycol chain, such as polyethylene glycol, polypropylene glycol, their derivatives, etc., is fixed on the surface and/or inside of the membrane. As examples of the mode of the fixation there are mentioned fixation by entanglement of the molecules forming the membrane and the molecules of the polyether compound, physical fixation of both molecules by the anchor effect, and chemical fixation of both molecules by the formation of covalent bond or ionic bond. Said ion-exchange membrane can be preferably used in case of removing low molecular weight electrolytes from an aqueous solution containing low molecular weight electrolytes and high molecular weight organic ions etc. through electrodialysis.

Abstract: An electrodeionization apparatus and method for purifying a fluid. A fluid, such as water, can be purified by removing weakly ionizable species from the fluid. Weakly ionizable species may be dissociated at different pH levels to facilitate removal from the fluid in an electrodeionization device.

Abstract: An electrodialysis apparatus includes a stack of alternating cation and anion semi-permeable, ion-selective membranes disposed between a positive DC potential anode electrode and a negative DC potential cathode electrode. The cation and anion selective membranes can be selective for monovalent or multivalent ions and form compartments therebetween through alternate compartments of which flow concentrate and diluate solutions such that the concentrate and diluate solutions are separated from each other by the ion selective membranes. Due to the potential maintained across each of the compartments and the cation and anion selective membranes separating the compartments, cations and anions as well as water will migrate from the diluate solution to the concentrate solution.

Abstract: A method and a device for the regeneration of an electroless metal deposition bath containing hypophosphite ions by electrodialysis is described. The method according to the invention and the device differ from the prior art in that the bath solution is led simultaneously through diluate compartments in a second electrodialysis unit having cathodes and anodes, which compartments are separated from concentrate compartments in the second electrodialysis unit on the cathode side by monoselective anion-exchange membranes and on the anode side by anion-exchange membranes, the diluate compartments and the concentrate compartments in the second electrodialysis unit being disposed alternately to one another.

Abstract: Feed water, fed through an inlet 6 into a desalting compartment 8, flows around the end 4a of a anion-exchange membrane 4 surrounding an anode 2a. The feed water enters into a portion defined between the anion-exchange membrane 4 and a cation-exchange membrane 5, and flows around the end 5a of the cation-exchange membrane 5 surrounding a cathode 3a. Then, the water to be treated further flows around the ends 4b, 5b of ion-exchange membranes 4, 5 surrounding an anode 2b and a cathode 3b, respectively, and then flows out through a product water outlet 7. A part of product water is supplied to the concentrated water circulating within the concentrating compartment 30, 40. A part of the concentrated water flowing out of the concentrating compartment 30, 40 is added to concentrated water circulating within the concentrating compartment 10, 20. The diffusion of silica from the concentrating compartment is restricted. As a result, final product water containing extremely low silica concentration is obtained.

Abstract: A process is disclosed for removing heat stable amine salts using an electrodialysis process. The process of the present invention can be used to reduce the level of heat stable salts in a lean solvent stream in an acid gas removal process. A base is added to the electrodialysis unit in order to permit the recovery of the heat stable amine salts as salts corresponding to the base added. The purified amine solution can be used again to remove acid gases from a gas stream.

Abstract: Electrodeionization apparatus and method. The electrodeionization apparatus includes an ion-depleting compartment in which alternating layers of an electroactive media are positioned. One of the alternating layers is doped to provide a more balanced current distribution through the apparatus. The method involves providing reducing the difference in conductivity between the alternating layers positioned in the ion-depleting compartment by adding a dopant material to one of the layers.

Abstract: An apparatus and process produces salts by an electrodialysis operation. The basic electrodialysis apparatus is a cell having a number of compartments separated by membranes. A DC source is connected to drive a current through a feed stream passing through the cell which splits the salt stream into an acid and a base. The incoming feed may be nanofiltered to remove divalent metal. The base loop may be in communication with an ion exchange column packed with a material that removes multivalent cations. Depending upon the material being processed and the desired end result either or both the nanofiltration and the ion exchanged column may be used in the apparatus.

Abstract: An apparatus and the process produces salts by an electrodialysis operation. The basic electrodialysis apparatus is a cell having a number of compartments separated by membranes. A DC source is connected to drive a current through a feed stream passing through the cell which splits the salt stream into an acid and a base. The incoming feed may be nanofiltered to remove divalent metal. The base loop may be in communication with an ion exchange column packed with a material that removes multivalent cations. Depending upon the material being processed and the desired end result either or both the nanofiltration and the ion exchanged column may be used in the apparatus.