Ion Exchange Chromatography:
Amongst various separation techniques, ion exchange is the most popular name because of its use for water softening. That is also unique in terms of its versatility and historical establishment. Besides the well-known use of ion exchangers in water treatment, they search use in organization, nuclear fuel processing, hydrometallurgy, agriculture and biology. A treatment of water through solid adsorbents is as old as civilization. There are records available which in the time of Aristotle, sand filters were used for purification of sea water. A Moses used a tree branch for making bitter water sweet. But the credit of recognizing the ion exchange phenomenon goes to two agricultural chemists-Thompson and Way. They observed the exchange of ammonium ions with calcium ions in soils. A realization of the fact which certain clay minerals were responsible for the exchange, led to the attempts to use like materials for water softening. It also prompted scientists to synthesize materials with similar properties.
The first synthetic ion exchanger was prepared in 1903 by two German chemists-Harm and Rumpler. The other German, Gans, worked on various pioneering applications of permutits. Other than the permutits could not stand in the market because of their poor reproducibility and chemical stability.
A real breakthrough in the subject came in 1935 when two English chemists, Adams, and Holmes, observed that crushed phonograph record exhibited ion exchange properties. This observation led to the synthesis of several organic ion exchangers which had better properties. It was describe in which stable and high capacity cation exchangers could be prepared as sulphonic acid resins and polyamine type resins exhibited anion exchange properties. An area of ion exchange blossomed at a very fast rate. The versatility of ion exchange resins was readily recognized. Many attempts have been made to modify and improve the existing materials. It is possible to tailor make ion exchange resins for specific applications.