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Cation-exchange capacity (CEC) is a measure of how many cations can be retained on soil particle surfaces. [1] Negative charges on the surfaces of soil particles bind positively-charged atoms or molecules (cations), but allow these to exchange with other positively charged particles in the surrounding soil water. [ 2 ]
Polystyrene sulfonate, a cation-exchange resin, is typically supplied with Na + as the counterion.. In chemistry, a counterion (sometimes written as "counter ion", pronounced as such) is the ion that accompanies an ionic species in order to maintain electric neutrality.
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 ...
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 ...
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.
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.
This is done in a configuration called an electrodialysis cell. The cell consists of a feed (dilute) compartment and a concentrate compartment formed by an anion exchange membrane and a cation exchange membrane placed between two electrodes. In almost all practical electrodialysis processes, multiple electrodialysis cells are arranged into a ...
An ion-exchange membrane is generally made of organic or inorganic polymer with charged (ionic) side groups, such as ion-exchange resins. Anion-exchange membranes contain fixed cationic groups with predominantly mobile anions; because anions are the majority species, most of the conductivity is due to anion transport.