Ion exchange polymers:

The unit begins with a historical background of the process of ion exchange and focuses on the point that the most important breakthrough in the field was the discovery of ion exchange resins. The cation, anion and amphoteric exchangers are known. The basic features of ion exchange mechanism are discussed. There are organic and inorganic ion exchangers but the former dominate the field. Some important features of synthesis of ion exchange resins are discussed.

There are two main routes of synthesis-condensation polymerization, and addition polymerization. Because of certain advantages, the addition polymerization has taken an edge over the condensation polymerization route. An idea is given about the trade names of different types of ion exchangers assigned by the manufacturers and the information generally provided on the labels.

The ion exchange polymers are very complex materials and some of their characteristics have to be properly understood before they are put to use. The different properties discussed in detail are moisture content, particle size, cross-linkage, capacity, and distribution ratio, equivalency of exchange and resin selectivity.

The different methods used for operating ion exchangers are elaborated. The mechanism operating during the uptake of cations in mixed aqueous organic media is explained. This is followed by discussion on chelating resin and synthetic inorganic ion exchangers. The important features, classes, advantages and drawbacks of these types of exchangers are discussed.

The unit concludes with a discussion on applications. There are too many applications. But for the purposes of clarity of presentation, only a few representative ones are cited and they are discussed under different groups.