Ion Exchange – Operation technologies

First of all, let's recall the definition of the unitary ion exchange process. Ion exchange is a chemical process in which ions of a certain charge present in a solution are removed from that solution by adsorption onto a generally solid material (rarely an immiscible liquid), to be replaced by an equivalent quantity of other ions of the same charge from the solid material (the ion exchanger).

In the light of the general considerations set out in the article "Ion exchange. Basic principles" [J 2 783] , we will first examine how ion exchange resins are used in practice, with particular reference to regeneration methods.

We'll then look at the different types of columns used in water treatment and other fields, with some construction details: columns allowing periodic lifting of resins, or compact beds that improve regeneration efficiency and the quality of the treated solution (water or other liquid); the most common water treatment linkages; mixed-bed finishing columns, etc.

A complete calculation of industrial water demineralization is provided, with details of the useful capacities of resins and regenerants.

Special water treatment processes, such as organic matter or nitrate removal, brackish water or condensate treatment, are covered in a third article [J 2 785] , which also contains a wide-ranging overview of ion exchange applications outside water treatment, with several examples.