Zeolites are just like clay minerals because both are composed of aluminosilicates

INTRODUCTIONS:
Zeolites are just like clay minerals because both are composed of aluminosilicates, although they differ in their crystal structure in that clay minerals deform in water showing expansion and contraction while zeolites are stable and rigid in water [8]. Both natural and synthetic zeolites are basically composed of aluminosilicates they may differ in the Si/Al ratio and pore sizes. Zeolites as defined by the mineralogist community ?? is a crystalline aluminosilicate with a 4-connected tetrahedral framework structure enclosing cavities occupied by large ions and water molecules both of which have considerable freedom of movement permitting ion exchange and reversible dehydration. ??[6]. Fig1
The tetrahedral structure of these micro porous aluminosilicates is of the form where T can be either Al or Si. The silicon based framework () structure is uncharged or neutral but when Al is introduced into this structure () a negative charge is induced due to shortage of electron from the Al with valence of taking the place of Si with . This has to be neutralized by extra cations attaching themselves to the structure [5]. In summary one can say the stability of the zeolite structure depends on the ratio of Si/Al. with higher ratio of these elements the zeolites have better stability for example in acidic environments. For Si/Al ratio >10 the framework may be considered as having high silica. Zeolites may have the following structural formula. ..[5] .Where the first part represent extra framework cations, the middle term is the framework and the last part is the sorbed phase. Zeolites are unique considering their inherent physicochemical properties and a lot of researchers and scientists worldwide have developed interest in exploiting and utilizing the valuable properties of these minerals since from their first discovery. The name zeolite is of Greek origin simply meaning boiling stone considering the facts that water is fast lost from it when heated [1] and this is an important property of the zeolite opening door for many applications. These minerals occur in nature in sedimentary deposits and can also be artificially made in the laboratories [6], pore sizes being determined by intended purpose and application, in fact this is one of the advantages of the synthetic zeolites. They exist in 3D structures [8] with cavities that houses cations, organic and water molecules. The structure of the zeolite is not affected when elements and ions are removed from their cavities.

THE ZEOLITE STRUCTURE.