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Cation-exchange capacity is measured by displacing all the bound cations with a concentrated solution of another cation, and then measuring either the displaced cations or the amount of added cation that is retained. [1] Barium (Ba 2+) and ammonium (NH 4 +) are frequently used as exchanger cations, although many other methods are available. [4] [5]
There are also amphoteric exchangers that are able to exchange both cations and anions simultaneously. However, the simultaneous exchange of cations and anions is often performed in mixed beds, which contain a mixture of anion- and cation-exchange resins, or passing the solution through several different ion-exchange materials. Ion exchanger.
Cation exchange chromatography is used when the desired molecules to separate are cations and anion exchange chromatography is used to separate anions. [11] The bound molecules then can be eluted and collected using an eluant which contains anions and cations by running a higher concentration of ions through the column or by changing the pH of ...
The cation transport number of the leading solution is then calculated as t + = z + c L A F I Δ t {\displaystyle t_{+}={\frac {z_{+}cLAF}{I\Delta t}}} where z + {\displaystyle z_{+}} is the cation charge, c the concentration, L the distance moved by the boundary in time Δ t , A the cross-sectional area, F the Faraday constant , and I the ...
Idealized image of cation-exchange resin performing water softening. It shows sodium ions being released by the resin, and replaced with calcium ions captured from water. Water softening is the removal of calcium, magnesium, and certain other metal cations in hard water.
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.
An ion-exchange membrane is a semi-permeable membrane that transports certain dissolved ions, while blocking other ions or neutral molecules. [1] Ion-exchange membranes are therefore electrically conductive. They are often used in desalination and chemical recovery applications, moving ions from one solution to another with little passage of ...
The positively charged species (e.g., sodium) in the D stream migrate toward the negatively charged cathode and pass through the negatively charged cation-exchange membrane. These cations also stay in the C stream, prevented from further migration toward the cathode by the positively charged anion-exchange membrane. [8] As a result of the anion ...