Relationships between the water content of zeolites and their cation population

• The volume of an equivalent cation was used to describe the cation population of a zeolite.
• A linear relation between water content of zeolites and their cation population was found.
• The volume of cavities and channels of a zeolite was determined.
• A void volume was found and estimated for each cationic form of each zeolite.

The weight percent water content of various cation-exchanged forms of zeolites X and Y, two samples of natural clinoptilolite, and a synthetic analcime were studied. A simple linear relation was established between the weight percent water content of various cation-exchanged zeolite samples and the quantity Veq cat which is the volume of a single hypothetical equivalent cation, representing the cation population of a zeolite. This goal was fulfilled by setting up a simple model of the zeolite in which the volume of its cavities and channels is occupied by water molecules and by the exchangeable cations. The proposed model indicates the presence of void volumes (the portion of the cavities and channels occupied neither by cations nor water molecules) and allows its evaluation. The linear relation found in this work may be used to estimate the water content of various cation exchanged forms of zeolites.

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