Adsorption of alkali chloride and ammonium halide on halloysite

It is generally accepted that broken bonds are the major cause of cation exchange in kaolin minerals, although the studies of a “fireclay” type of kaolin mineral (8) and hydrated halloysite (12, 15) seem to indicate that lattice substitutions, such as that found for 2 : 1 type of clay minerals, account for the fairly large parts of the cation-exchange capacities of some kaolin clays, particularly with poor crystallinity.