ABSTRACT
The intentional use of ion exchange, without knowledge of its theoretical nature, based purely on empirical experience, occurred a number of centuries later; in 1623, Francis Bacon described a method for removing salt from sea water. During 1850 to 1855, the agrochemist Way published a number of papers dealing with the behavior of soils in the presence of various cations. During the period between the 1930s and 1940s, inorganic ion-exchange sorbents were replaced in almost all fields by the new organic high-molecular-weight ion exchangers. Chemical stability is an additional criterion that emphasizes the basic difference between organic ion exchangers and inorganic ion-exchange sorbents. Organic ion exchangers and especially copolymers can be prepared with defined grain size, are resistant to abrasion, and are thus useful for use in packed columns. The ionic selectivity of organic ion exchangers is given primarily by the character of the functional groups incorporated in the polymer skeleton and by the degree of cross-linking.
