Methods, systems, and techniques for removing ammonium from ammonia-containing water involve using a stack that has alternating product chambers and concentrate chambers for receiving ammonia-containing water and an acidic solution, respectively, with the chambers being bounded by alternating cation exchange membranes and proton permselective cation exchange membranes. Ammonium moves from the product chambers to the concentrate chambers across the CEMs and protons move from the concentrate chambers to the product chambers across the pCEMs when the stack is in use. An electrolyzer may also be used to convert the ammonium in the concentrate chambers into nitrogen.

A device for the electrodeionization of a sample liquid. The device has an anode chamber having two openings and an anode, a cathode chamber having two openings and a cathode, and a treatment chamber, that is arranged between the anode chamber and the cathode chamber and has two openings and ion exchanger. The anode chamber and the cathode chamber are separated from the treatment chamber in each case by a permselective membrane and an energy source is operatively connected to the anode and the cathode. In addition, a method for the electrodeionization of a sample liquid is provided.

The present disclosure relates to a membrane apparatus for selectively retaining and releasing target cations, such as lithium. The membrane apparatus comprises a cation exchange layer and an anion exchange layer that are coupled and configured for hydraulic communication with sufficient permselectivity to facilitate water splitting under an applied voltage. The cation exchange layer comprises a sorbing agent that has a target cation binding coefficient that is less than its hydrogen ion binding coefficient such that it may be efficiently regenerated by in situ produced hydrogen ions. Electrically regenerated ion exchange devices and methods are also described.

Between two juxtaposed similar ion exchange membranes (AEMs or CEMs), an ion depletion zone and ion enrichment zone are generated under an electric field. As cations are selectively transferred through the CEMs, for example, anions are relocated in order to achieve electro-neutrality, resulting in the concentration drop (increase) in ion depletion (enrichment) zone. The use of a sacrificial metal anode allows electrocoagulation (EC) concurrently with ICP thereby permitting concentration of both ionic and non-ionic impurities to occur at the same time within the same cell or device.

An electrodialysis module includes at least one base unit. The base unit includes a working tank, a first ion-exchange membrane, a second ion-exchange membrane, at least one first electrode, and at least two second electrodes. The first ion-exchange membrane and the second ion-exchange membrane are located in the working tank. The first ion-exchange membrane and the second ion-exchange membrane together divide the working tank into two electrode compartments and a desalination compartment therebetween. The at least one first electrode is disposed in the desalination compartment. The at least two second electrodes are disposed in each of the electrode compartments, respectively, in which the at least two second electrodes and the at least one first electrode have different polarities.

Embodiments of this disclosure use ion-selective electrodialysis to separate ions from geothermal brines, leading to an enrichment and isolation of lithium while concurrently producing hydrogen and chlorine gas (chlor-alkali electrodialysis) and capturing carbon dioxide gas in the form of carbonate. An electrodialysis apparatus can include seven compartments or tanks, one anode, two cathodes, and non-selective and valent-selective ion exchange membranes to yield lithium carbonate. This technology can be extended with additional electrodialysis apparatus to yield lithium hydroxide.

Processes, systems, and techniques for multivalent ion desalination of a feed water use an apparatus that has a cathode, an anode, and an electrodialysis cell located between the cathode and anode. The cell has a product chamber through which the feed water flows, a multivalent cation concentrating chamber on a cathodic side of the product chamber through which the concentrated multivalent cation solution flows, and a multivalent anion concentrating chamber on an anodic side of the product chamber through which the concentrated multivalent anion solution flows. The product chamber and the multivalent cation concentrating chamber are each bounded by and share a cation exchange membrane, and the product chamber and the multivalent anion concentrating chamber are each bounded by and share an anion exchange membrane. A monovalent ion species is added to at least one of the concentrated multivalent cation solution and the concentrated multivalent anion solution.

Methods, systems, and techniques for removing ammonium from ammonia-containing water involve using a stack that has alternating product chambers and concentrate chambers for receiving ammonia-containing water and an acidic solution, respectively, with the chambers being bounded by alternating cation exchange membranes and proton permselective cation exchange membranes. Ammonium moves from the product chambers to the concentrate chambers across the CEMs and protons move from the concentrate chambers to the product chambers across the pCEMs when the stack is in use. An electrolyzer may also be used to convert the ammonium in the concentrate chambers into nitrogen.

Between two juxtaposed similar ion exchange membranes (AEMs or CEMs), an ion depletion zone and ion enrichment zone are generated under an electric field. As cations are selectively transferred through the CEMs, for example, anions are relocated in order to achieve electro-neutrality, resulting in the concentration drop (increase) in ion depletion (enrichment) zone. The use of a sacrificial metal anode allows electrocoagulation (EC) concurrently with ICP thereby permitting concentration of both ionic and non-ionic impurities to occur at the same time within the same cell or device.

The present disclosure provides methods of improving the monovalent selectivity of the anion exchange membrane. When operating electrodialysis in a high salinity brine, the high salinity solution enables monovalent selective transport. The monovalent selectivity can significantly retard divalent anion transport, such as SO.sub.4.sup.2, and is particularly useful during lithium extractions from brines. Such selectivity can be utilized in many operation containing high concentration of salt solution such as sea salt extraction, lithium production, and the production of chloroalkanes.