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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 ]
An advantage of this method is that exchangeable cations can be removed by passing a chloride solution through the plate once the sample has been dried. Exchanging cations can be useful when establishing peaks for standards with variable interlayer cations. For example, nontronite has an interlayer which can contain both calcium and sodium. If ...
The presence of sodium as the predominant exchangeable cation can result in the clay swelling to several times its original volume. Hence, sodium montmorillonite has come to be used as the major constituent in nonexplosive agents for splitting rock in natural stone quarries in an effort to limit the amount of waste, or for the demolition of ...
Exchangeable cations are present in the clay minerals interlayers and on the external basal planes of clay platelets. Cations also compensate the negative charges on the clay particle edges caused by the protolysis of silanol and aluminol groups ( pH dependent charges).
The sodium adsorption ratio (SAR) is an irrigation water quality parameter used in the management of sodium-affected soils.It is an indicator of the suitability of water for use in agricultural irrigation, as determined from the concentrations of the main alkaline and earth alkaline cations present in the 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.
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.
CEC is the amount of exchangeable hydrogen cations (H +) that will combine with 100 grams dry weight of soil and whose measure is one milliequivalent per 100 grams of soil (1 meq/100 g). Hydrogen ions have a single charge and one-thousandth of a gram of hydrogen ions per 100 grams dry soil gives a measure of one milliequivalent of hydrogen ion.