Abstract: Systems and methods for continuous real-time sweat sampling and analysis are disclosed. A sweat collection article and method of collecting sweat from a person's skin using the sweat collection article are provided. The sweat collection article includes: a sweat collecting tube placed adjacent to the person's skin, and at least one piece of flexible material that has an adhesive that adheres the article to the person's skin and is positioned to overlie one end of the tube. The second end of the sweat collecting tube is in fluid communication with an instrument such as a mass spectrometer that analyzes the sweat on a real-time basis. The systems and methods may further include a device for removing salt from the sweat that is arranged so that the sweat is transported to the device prior to being transported to the instrument for analyzing the sweat.

Abstract: Systems and methods for continuous real-time sweat sampling and analysis are disclosed. In one case, a sweat collection device and method of using the same are provided. The sweat collecting device has a main body with a sweat-collecting surface that is placed adjacent the person's skin. A sweat collecting tube is provided. The first end of the sweat collecting tube is joined to a bore in the main body of the device and the second end extends outward therefrom. In another case, a sweat collection article and method of collecting sweat from a person's skin using the sweat collection article are provided. The sweat collection article includes: a sweat collecting tube placed adjacent to the person's skin, and at least one piece of flexible material that has an adhesive that adheres the article to the person's skin and is positioned to overlie one end of the tube.

Abstract: A photodialysis device that can desalinate saline streams is described herein. The device can have a desalination rate that is significantly faster than current solar thermal desalination technology. Salt is removed from water by passing ionic current derived from sunlight through this water using dye-sensitized membranes. The device can serve as a distributed, low-cost technology that can efficiently and effectively desalinate low salinity sources of water, which is particularly useful for agriculture and drinking water applications.

Abstract: Methods and circuits for a device for interrupting concentration-related polarisation phenomenon and for self-cleaning of electromembrane processes by application of asymmetric inverse-polarity pulses with high intensity and variable frequency are described. The device, a bipolar switch, is based on the use of solid-state electronics to carry out polarity inversion in a range of frequencies, intensities and pulse widths to prevent or reduce formation of precipitates on the surfaces of the membranes. The inversion protocol, with a frequency that varies as a function of the appearance of dirt on the membranes, as measured by the decrease in voltage or electrical resistance of the membrane cell during electromembrane processes, is also provided. This device and configuration provides application of modulated and stable high-intensity pulses using a second power source.

Abstract: A system comprises an electrodialysis apparatus, which includes first and second reservoirs, wherein a salt concentration in the first reservoir reduces below a threshold concentration and salt concentration in the second reservoir increases during an operation mode. A first electrode comprises a first solution of a first redox-active electrolyte material, and a second electrode comprises a second solution of a second redox-active electrolyte material. In a first reversible redox reaction between the first electrode and first electrolyte material at least one ion is accepted from the first reservoir, and in a second reversible redox reaction between the second electrode and second electrolyte material at least one ion is driven into the second reservoir. A first type of membrane is disposed between the first and second reservoirs, and a second type of membrane, different from the first type, is disposed between the respective electrodes and reservoirs.

Abstract: Electrodialysis cell systems for water deionization is provided. Also provided are methods for using the electrodialysis cell systems. The cells use the forward and reverse reactions of a redox mediator and the combined operations of a deionization cell and an ion-accumulation cell to enable sustainable deionization with a significantly decreased operating voltage, relative to conventional deionization cells. The cells have applications in seawater desalination, water purification, and wastewater treatment.

Abstract: Electrodialysis stacks comprising a series of electrodialysis cells and anaerobic digestion systems incorporating the electrodialysis stacks are provided. Also provided are methods of using the electrodialysis stacks and systems to recover nitrogen, in the form of ammonia, from separated anaerobic digestate. The electrodialysis stacks use monovalent-selective cation exchange membranes to concentrate ammonium ions and other monovalent ions in a concentrate stream, while discriminating against multivalent cations, which, as a result, are retained in a diluate stream. The electrodialysis stacks may use monovalent-selective anion exchange membranes to discriminate against multivalent anions, which, as a result, are selectively retained in a diluate stream.

Abstract: An electrodialytic buffer generator is described. The buffer generator may include a central buffer-generating channel having an inlet and outlet, a second chamber, and a third chamber. The buffer-generating channel, the second chamber, and the third chamber may each include an electrode. The buffer generator may also include a first ion exchange barrier and a second ion exchange barrier. The first ion exchange barrier can be disposed between the second chamber and the buffer-generating channel. The second ion exchange barrier can be disposed between the third chamber and the buffer-generating channel.

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 for continuously manufacturing lithium transition metal phosphates of the formula LiMPO4, comprising the steps of providing an aqueous reaction mixture containing LION, H3PO4, and a transition metal sulphate, converting the reaction mixture into a lithium transition metal phosphate, separating the solid lithium transition metal phosphate from the soluble part of the reaction mixture, subjecting the soluble part (diluate) to an electrodialysis, and isolating the part of the electrodialysate that contains an aqueous LiOH solution.

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 describes processes for the production of basic aluminum compounds, including aluminum chlorohydrate, basic zirconium compounds, and basic aluminum zirconium compounds. The process produces products of a wide range of basicities. The products formed by the present invention are comprised of low molecular weight species characteristic of enhanced efficacy antiperspirant salt compositions. The products of this process are suitable for use as water purification agents, as binders in catalyst applications, and in antiperspirant applications. In addition, the invention is directed to the products made by the disclosed process.

Abstract: A desalination system is provided. The desalination system comprises a desalination apparatus. The desalination apparatus comprises first and second electrodes, and a first group of paired ion exchange membranes disposed between the first and second electrodes to form a first group of alternating first and second channels. The first channels are configured to receive a first stream for desalination and the second channels are configured to receive a second stream to carry away ions removed from the first stream, respectively. The desalination apparatus further comprises a plurality of spacers disposed between each pair of the adjacent ion exchange membranes and between the first and second electrodes and the respective ion exchange membranes. Wherein each of the ion exchange membranes in the first group is a cation exchange membrane. A desalination system and a method for removing ions from an aqueous stream area also presented.

Abstract: A process for producing a gas using an electrodialysis apparatus includes flowing at least two solutions and an electrode solution into the apparatus, pressurizing the apparatus at a stack pressure, applying a voltage to the apparatus's electrodialysis stack so a dissolved gas is generated in the second solution, flowing the second solution out of the apparatus, regenerating the gas out of the second solution, and collecting the gas. A process for generating a product, like a gas, liquid, or supercritical fluid, using an electrodialysis apparatus includes flowing at least two solutions and an electrode solution into the apparatus, adjusting the temperature and pressure so the product will be generated from the second solution, applying a voltage to the electrodialysis stack of the apparatus so that the product is generated in the second solution, flowing the second solution out of the apparatus, and regenerating the product from the second solution.

Abstract: The invention relates, in particular, to a process for treating a liquid medium loaded with nitrates via a chemical route that mainly comprises a step of electrolysis of the liquid medium in the presence of a metal salt, the electrolysis being carried out at a pH below 5. The invention also relates to a device for treating a liquid medium loaded with nitrates and also to the applications of this process and device, in particular for reducing the level of nitrates in drainage waters.

Abstract: A system and method for recovery of CO2 includes an aqueous capture device having a capture solution. The aqueous capture device is arranged to receive gas and to capture components from the gas including at least CO2. An electrodialysis unit in operative connection with the capture device performs an electrodialysis operation on the capture solution including at least the CO2, wherein a CO2 rich process stream and a regenerated capture solution are generated from the capture solution including at least the CO2. The CO2 rich process stream is a pressurized process stream at a pressure which maintains the CO2 substantially within the CO2 rich process stream, while in the electrodialysis unit. In another alternative, at least the pH of the capture stream is controlled.

Abstract: The process, according to the invention, comprises the following stages: (a) processing (1) of the laterite ore (O) by crushing, scrubbing, attrition, separation, and high-intensity magnetic separation; (b) Leaching (2) of the non-magnetic fraction (CN) obtained form the previous stage (a); (c) optionally, neutralization (3) of the effluent from the leaching and/or solid-liquid separation stages (4); (d) treatment of the effluents from stages (b) or (c) using an ion-exchange hybrid system (5) comprising at least one circuit for removal of impurities and at least one circuit for recovery of nickel and cobalt; (e) elution (6) of the ion-exchange resin used; (f) separation, purification, and recovery (7) of the nickel and cobalt.

Abstract: Sludge is treated in a treatment chamber by providing a pair of electrodes in the treatment chamber and applying an electrical current between the electrodes such that one of the electrodes functions as an anode and one of the electrodes functions as a cathode in proximity to the outlet. A flow of water is induced from the sludge towards the outlet by the electrical current. An ion exchange textile comprising exchangeable functional groups grafted thereon is located in proximity to at least one of the electrodes such that the ionic forms of the metals are exchanged with the functional groups on the ion exchange textile. Accordingly the sludge is dewatered and metals in the sludge are captured commonly in the treatment chamber while the electrical current simultaneously inactivates pathogens in the treatment chamber.

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: 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: A process is provided for separating, concentrating and recovery of boron compound from aqueous solution containing boron, strongly dissociated anions and some cations. The process specifically integrates electrodialysis with ion exchange to selectively separate boron from aqueous solution that contains a wide concentration range of boron, strongly ionised anions such as chloride, nitrate and sulfate, and cations like lithium. The process is adapted for controlling boron concentration in an industrial process, for the recovery or purification of boron and some cations like lithium form aqueous solutions, and for wastewater treatment.

Abstract: An apparatus for regulating salt concentration, a lab-on-a-chip including the same and a method of regulating salt concentration using the apparatus are provided. The apparatus includes: a reaction chamber that is defined by a cation exchange membrane and an anion exchange membrane and is selected from the group consisting of a biomolecule extraction chamber, an amplification chamber, a hybridization chamber, and a detection chamber; a first electrode chamber that is defined by the anion exchange membrane and a first electrode and includes an ion exchange medium; and a second electrode chamber that is defined by the cation exchange membrane and a second electrode and includes an ion exchange medium. Even without injecting solutions with different salt concentrations into the reaction chamber by operating pumps and valves for each operation stage, the salt concentration can be reversibly regulated in situ by adjusting the polarity, intensity and application time of a voltage.

Abstract: In one embodiment, a system comprises a filter and at least one electrodeionization (EDI) unit for chemical recovery. The filter is adapted to receive a fluid and to remove a selected chemical element or contaminant from the fluid. The EDI unit is coupled to the filter and adapted to recover a chemical element from the fluid and to separate the recovered chemical element from the fluid.

Abstract: A new method for improving the efficiency of electrodialysis (ED) cells and stacks, in particular those used in chemical synthesis. The process entails adding a buffer solution to the stack for subsequent depletion in the stack during electrolysis. The buffer solution is regenerated continuously after depletion. This buffer process serves to control the hydrogen ion or hydroxide ion concentration so as to protect the active sites of electrodialysis membranes. The process enables electrodialysis processing options for products that are sensitive to pH changes.

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: 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: 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 present invention generally provides an apparatus and method for removing contaminants from a plating solution. The apparatus generally includes a plating cell having an electrolyte inlet and an electrolyte drain, an electrolyte storage unit in fluid communication with the electrolyte inlet, and an electrodialysis chamber in fluid communication with the electrolyte drain, wherein the electrodialysis chamber is generally configured to receive a portion of used electrolyte solution and remove contaminants therefrom. The method generally includes supplying an electrolyte solution to a copper plating cell, plating copper onto a substrate in the plating cell with the electrolyte solution, removing used electrolyte solution from the plating cell, and refreshing a portion of the used electrolyte solution with an electrodialysis cell.

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: 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: A method for electrodialysis is conducted in a multi-compartment, preferably a four compartment, electrodialysis cell configuration wherein an inexpensive source of protons, preferably from a strong inorganic acid enables the conversion of multivalent metal salts into valuable acid products, such as 2-keto-L-gluconic acid, a vitamin C precursor, and useful by-products, like calcium chloride.

Abstract: The present invention generally provides an apparatus and method for removing contaminants from a plating solution. The apparatus generally includes a plating cell having an electrolyte inlet and an electrolyte drain, an electrolyte storage unit in fluid communication with the electrolyte inlet, and an electrodialysis chamber in fluid communication with the electrolyte drain, wherein the electrodialysis chamber is generally configured to receive a portion of used electrolyte solution and remove contaminants therefrom. The method generally includes supplying an electrolyte solution to a copper plating cell, plating copper onto a substrate in the plating cell with the electrolyte solution, removing used electrolyte solution from the plating cell, and refreshing a portion of the used electrolyte solution with an electrodialysis cell.

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: A method for producing deionized water by an electro-regenerating deionization method, which comprises employing a deionized water producing apparatus comprising an electrodialyzer, and ion exchangers being accommodated in the demineralizing compartments, supplying water to be treated in the demineralizing compartments and supplying a concentrated water to the concentrating compartments, wherein the concentrated water at the outlet of the concentrating compartments has a S value of 7 or more as defined by the following formula (1) and a pH of 2.5 or more: S value=(&ggr;−420000×A)/(B×(1−(A/0.004))3)  Formula(1), wherein &ggr; is electro-conductivity(&mgr;S/cm), A is hydrogen ion concentration (mol/l), and B is magnesium ion concentration (ppb).

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: Processes are provided for the electrodialysis of a (di)alkali metal salt of an aromatic hydroxycarboxylic acid to produce a free aromatic hydroxycarboxylic acid and the alkali metal hydroxide, in the presence of a selected alkali metal salt. These various embodiments represent efficient and economical methods for recovering the alkali metal hydroxide, as well as the parent organic compound, from these dialkali metal salts. These processes also desirably prevent overvoltage during the electrodialysis.

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: An electrodialytic cell and process for its use in regenerating electroless plating solutions, particularly nickel-hypophosphite electroless plating solutions, are disclosed. The process is capable of operating at high temperatures and in a continuous fashion such that the plating operation is not interrupted and the steady state condition in the plating bath is achieved.

Abstract: This invention relates to methods of controlling the oxidation of hydrocarbons to respective dibasic acids, such as adipic acid for example, by removing the catalyst from the reaction mixture, outside the reaction zone, after the oxidation has taken place at least partially. The catalyst is precipitated substantially in its totality by using a base, preferably sodium hydroxide, to form the catalyst hydroxide, such as cobalt hydroxide for example. Preferably, the precipitated catalyst is recycled to the reaction zone with or without further treatment. The method may also include steps for treatment of the reaction mixture by hydrolysis and/or electrodialysis.

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 ion exchange 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. Monovalent selctive cation membranes may be used to effect preferential treatment of the monovalent cations to the base loop. 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: The present invention relates to a process for isolating, by membrane electrodialysis, a catalyst from a solution containing it. More precisely, it relates to the isolation of a catalyst used in a homogeneous phase molecular oxidation reaction. The invention consists of a process for isolating a homogeneous catalyst dissolved in a mixture also containing at least one aliphatic diacid, characterized in that the catalyst contains cobalt and the isolation is performed by membrane electrodialysis.

Abstract: The method of manufacturing nickel hypophosphite from a solution of hexahydrated nickel sulfate and a solution of monohydrated sodium hypophosphite by an electro-membrane technique, consists: a) in introducing respectively the hexahydrated nickel sulfate solution and the monohydrated sodium hypophosphite solution into each of two dilution circuits of four-compartment electrodialysis cells formed by alternating stacks of cationic and anionic homopolar membranes in an electrodialysis apparatus having an anode and a cathode that are insoluble; b) in applying an electrical current from the anode to the cathode without regulating the pH of the solutions contained in the dilution and concentration circuits but regulating the electricity supply, either in voltage or in current; and c) in recovering a hexahydrated nickel hypophosphite solution from one of the concentration circuits.

Abstract: A system for producing ultra-pure water having an electrodialysis unit 1, which has a membrane selectively permeable to monovalent cations and a membrane selectively permeable to monovalent anions, and a reverse osmosis unit 5 which is connected after the electrodialysis unit 1 in series.

Abstract: An on-site process and apparatus for producing hydrogen peroxide at a high efficiency substantially from brine and oxygen-containing gas alone as raw materials while removing alkaline earth metals. Sea water concentrated by an electrodialytic apparatus 2 or the like as a raw material is supplied to an impurity removing apparatus 10 where caustic soda produced in an acid-alkali producing apparatus 11 at a subsequent stage and/or carbon dioxide gas is added to remove alkaline earth metals contained in sea water in the form of a hydroxide or carbonate precipitate. Separately, the acid-alkali producing apparatus 11 performs a salt separating operation to produce caustic soda which is then supplied to a hydrogen peroxide generator 28 to produce an alkaline aqueous solution of hydrogen peroxide.

Abstract: In order to remove the salts (in particular NH.sub.4 Cl) present in an aqueous sulphonamide solution (in particular CH.sub.3 SO.sub.2 NH.sub.2), the solution is subjected to a two-compartment electrodialysis. By maintaining the pH at a value below 7, the formation of ammonia is avoided. The demineralized solution can be concentrated in order to receover after crystallization, the sulphonamide.

Abstract: Method of pre-treating a sample for metal analysis, the sample including a volatile alkali, by permeating the volatile alkali through a gas permeable membrane, dissolving the volatile alkali in an absorbent, passing ions through a first cation exchange membrane in electrical contact with an anode, reacting the volatile alkali with the ions, and passing the reacted volatile alkali through a second cation exchange membrane in electrical contact with a cathode, whereby the volatile alkali is removed from the sample.