الفهرس 
acknowledgmentOnly 14 pages are availabe for public view
 |  | from | 180 |  |  |
| | | from | 180 | | |
Abstract
It is well established that selectivity beh¬aviour in ion exchange reactions is controlled by several factors. Those factors can be grouped into thres groups; those related to the exchanger itself such as structure, charge density... etc; those related to the ions involved such as ionic size, hydration, polorisability.... etc. and those rel-ated to the solvent such as its dielectric const¬ant, adsorption on the surface of the exchanges..etc.
The ionic properties affecting selectivity are either gemeterical or electrical. Several authors Sisenman (6^4-). Sherry (59t58) Cremers and Laudelout (19) emphasixed the relation between the properties of ions in solutions and their behavi¬our in the adsorbed state. In zeolites these authors rraintain that the divalent ions are dissolved in the zeolitie water. Cremers and Laudlout (19) also Boyd and Soldano (13) demonstrated that the behaviour of adsorbed ions on clays, such as selective adsor¬ption and. surface mobility,