Disclosed is a process for enriching silicate content in drinking water that includes separating raw water via reverse osmosis into a permeate comprising demineralised raw water and a retentate comprising mineral enriched raw water. The permeate is mixed with a water glass solution comprising sodium silicate and/or potassium silicate. An ion exchange process is used to reduce the concentration of sodium and/or potassium ions in at least part of the mixture. At least part of the retentate is supplied to the mixture after reducing the concentration of sodium and/or potassium ions to provide a silicate-enriched drinking water. Also disclosed is an apparatus for producing a drinking water enriched with silicate. The apparatus includes a reverse osmosis unit, a mixing unit, an ion exchanger, and a feed unit for feeding at least part of the retentate to the mixture after reducing the concentration of sodium and/or potassium ions.

There are provided system for preparing lithium hydroxide from an aqueous composition comprising a lithium compound and use of the system thereof to prepare lithium hydroxide, the system comprising an electrochemical cell, a pH probe and at least one inlet for receiving acid or base for maintaining pH. For example, the lithium compound can be lithium sulphate and the aqueous composition can be at least substantially maintained at a pH having a value of about 2 to about 4.

There are provided processes for preparing a metal hydroxide comprising (i) at least one metal chosen from nickel and cobalt and optionally (ii) at least one metal chosen from manganese, lithium and aluminum, the process comprising: reacting a metal sulfate comprising (i) at least one metal chosen from nickel and cobalt and optionally (ii) at least one metal chosen from manganese, lithium and aluminum with lithium hydroxide, sodium hydroxide and/or potassium hydroxide and optionally a chelating agent in order to obtain a solid comprising the metal hydroxide and a liquid comprising lithium sulfate, sodium sulfate and/or potassium sulfate; separating the liquid and the solid from one another to obtain the metal hydroxide; submitting the liquid comprising lithium sulfate, sodium sulfate and/or potassium sulfate to an electromembrane process for converting the lithium sulfate, sodium sulfate and/or potassium sulfate into lithium hydroxide, sodium hydroxide and/or potassium hydroxide respectively; reusing the sodium hydroxide obtained by the electromembrane process for reacting with the metal sulfate; and reusing the lithium hydroxide obtained by the electromembrane process for reacting with the metal sulfate and/or with the metal hydroxide.

An acidic treatment liquid processing apparatus includes: a tank having an interior space; a diaphragm permeable to a metal cation and separating the interior space of the tank into a first chamber and a second chamber; a first electrode disposed in the first chamber; a second electrode disposed in the second chamber; a power supply configured to apply a voltage while using the first electrode as an anode and the second electrode as a cathode; a first liquid passing part configured to pass an acidic treatment liquid containing a dichromate ion and a metal cation into the first chamber; and a second liquid passing part configured to pass an acid aqueous solution into the second chamber.

In an acidic treatment liquid processing apparatus, a space between a first electrode and a second electrode spaced from each other is separated by a first diaphragm permeable and a second diaphragm into a first chamber, a second chamber, and a third chamber. While the first chamber is fed with an acidic treatment liquid containing a dichromate ion and a metal cation, the second chamber is fed with a first acid aqueous solution, and the third chamber is fed with a second acid aqueous solution, a voltage is applied using the first electrode as an anode and the second electrode as a cathode.

An electrodialysis device and method for selective removal of drinking water target ions were provided. It belongs to the technical field of drinking water safety. A method of electrodialysis with slightly brackish water is proposed. By means of ion electromigration control, the resistance is converted from the single membrane resistance to the diffusion boundary layer resistance; and the diffusion boundary layer is fully compressed by controlling the electrodialysis membrane, the electrodialysis membrane stack, and the electrodialysis process parameters. So that the relative electromigration rate of the target ions is improved. According to the method, the initial concentration effect, the competition effect, the synergistic effect, the concentration diffusion, the differential pressure permeation, and other influences of electrodialysis are integrated for selectively removing the target ions. It significantly reduces the cost of water treatment and improves the long-term stability and operational applicability of the device.

A composite membrane comprising: a) a first layer comprising a first porous support and a first ionic polymer present in the pores of the first porous support; b) a second layer comprising a second porous support and a second ionic polymer present in the pores of the second porous support; c) a third layer comprising a third porous support, a third ionic polymer and a fourth ionic polymer, wherein the third ionic polymer is present in the pores of the third porous support; wherein: (i) one of the first ionic polymer and the second ionic polymer is a cationic polymer and the other is an anionic polymer; (ii) the third layer c) is interposed between the first layer a) and the second layer b); (iii) the third ionic polymer comprises a network of pores and the fourth ionic polymer is present within the pores of the third ionic polymer; and (iv) one of the third ionic polymer and the fourth ionic polymer is a cationic polymer and the other is an anionic polymer.

A polymer film obtainable by curing a composition comprising a compound of Formula (I) wherein: R′ is vinyl, epoxy C.sub.1-3_alkylenethiol: n has a value of 1 or 2; m has a value of 1, 2 or 3; M′.sup.+ is a cation; wherein X is as defined in the claims; and wherein the molar fraction of the compound of Formula (I) in relation to all curable compounds in the composition is greater than 0.25. Also claimed are compositions, processes membranes and their uses.

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A method for separating and recovering carbon dioxide from ambient air includes continuously bringing ambient air into contact with a basic aqueous solution; electrodialysis of the solution using bipolar and anion-selective ion exchange membranes as well as recycling the depleted solution; separating CO.sub.2 from the enriched solution and recycling the solution depleted of CO.sub.2. The absorption is performed in an absorber, open basin, or a combination thereof. Separation is achieved by thermal desorption of CO.sub.2 by steam stripping to obtain a carbon dioxide/steam mixture; and/or by chemical reaction of the (hydrogen-) carbonate ions, in which the CO.sub.2 contained is converted into a water-insoluble salt or a gas and simultaneously removed from the solution. The pH of either obtained solution is measured before the recycling or before the separation, and is adjusted to a predetermined value. pH is measured and adjusted based on how absorption and separation are performed.

A single piece-type bipolar film roll with a mesh cloth support and a manufacturing method therefor. The single piece-type bipolar film roll is supported by a high-strength ultra-high molecular weight polyethylene mesh cloth, one side of the single piece-type bipolar film roll is a cation exchange layer containing a benzenesulfonic acid group, the other side of the single piece-type bipolar roll is an anion exchange layer containing a benzyl dimethyl butyl ammonium quaternary amino group, and the middle is a water dissociation catalyst layer containing a benzyl methyl butyl amine tertiary amino group, and the three layers form the single piece-type bipolar film roll. By providing a wider protective film and a narrower spacing film, a dipping and absorbing film roll is polymerized to prepare a composite base film roll which is then subjected to continuous sulfonation to prepare a single-sided sulfonated composite positive film roll, and then the unreacted blank side is sequentially subjected to three-step chemical reactions such as complete chloromethylation, complete tertiary amination and incomplete methylation, so as to prepare a single piece-type bipolar film roll having a compact structure, a clear middle interface, a high mechanical strength and a stable quaternary amino group, and the product qualification rate is high; and the single piece-type bipolar film roll is suitable for a bipolar film electrodialysis engineering application of an organic material-containing system.