Pretreatment of natural zeolites covers a wide range of modification techniques
leading in several products to a variety of applications. A very common pretreatment type
is used for producing modified zeolites for use in ion exchange applications and in
particular for the removal of cations from aqueous solutions. In these cases, pretreatment
aims to remove certain ions from the structure of the material and locate more easily
removable ones, prior to any ion exchange application. Practically, the result of any
pretreatment operation is the increase of the content in a single cation, what is called
homoionic form. The final homoionic or near homoionic state of the zeolites improves the
effective exchange capacity and performance in ion exchange applications.
Keywords: Pretreatment, inorganic salts, modification, ion exchange capacity,
homoionic zeolite, chemical treatment, physical treatment, modified zeolites,
effective capacity, breakthrough capacity, maximum exchange level.
