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Compared to RO membranes, ion exchange requires repetitive regeneration when inlet water is hard (has high mineral content). [citation needed] Industrial and analytical ion-exchange chromatography is another area to be mentioned. Ion-exchange chromatography is a chromatographical method that is widely used for chemical analysis and separation ...
For anionic resins, regeneration typically uses a solution of sodium hydroxide or potassium hydroxide. The waste waters eluted from the ion-exchange column containing the unwanted calcium and magnesium salts are typically discharged to the sewage system. [3] Recharge typically takes the following steps: [10]
Ion-exchange resin beads. An ion-exchange resin or ion-exchange polymer is a resin or polymer that acts as a medium for ion exchange, that is also known as an ionex. [1] It is an insoluble matrix (or support structure) normally in the form of small (0.25–1.43 mm radius) microbeads, usually white or yellowish, fabricated from an organic polymer substrate.
Co-current deionization refers to the original downflow process where both input water and regeneration chemicals enter at the top of an ion-exchange column and exit at the bottom. Co-current operating costs are comparatively higher than counter-current deionization because of the additional usage of regenerants.
Electrodeionization (EDI) is a water treatment technology that utilizes DC power, ion exchange membranes, and ion exchange resin to deionize water. EDI is typically employed as a polishing treatment following reverse osmosis (RO), and is used in the production of ultrapure water. It differs from other RO polishing methods, like chemically ...
In the case of a water softener, the cation exchange resin is exchanging sodium (the Na + ion of NaCl) for hardness minerals such as calcium and magnesium. A dealkalizer contains strong base anion exchange resin that exchanges chloride (the Cl – ion of the NaCl) for carbonate (CO − 3), bicarbonate (H C O − 3) and sulfate (SO 2− 4). As ...
For gel-type ion exchangers, selectivity reversal at very high ionic strength can also provide a solution. Sometimes the displacer is specifically designed with a titratable functional group to shift its affinity. After the displacer is washed out, the column is washed as needed to restore it to its initial state for the next run. [6] [7] [8]
Ion exchange: [9] Ion-exchange systems use ion-exchange resin- or zeolite-packed columns to replace unwanted ions. The most common case is water softening consisting of removal of Ca 2+ and Mg 2+ ions replacing them with benign (soap friendly) Na + or K + ions.