Ion exchange selectivity of phillipsite

Phillipsite is one of the main components of the sedimentary zeolite-rich rocks called zeolitites used in a variety of applications (i.e., in the field of pollution abatement and agriculture). The interest for the understanding of the cation exchange properties for a proper and efficient use in industrial applications prompted in 1995 a long term project on the systematics of cation exchanged phillipsites, their crystal chemistry and properties. Natural phillipsite samples with different Si/(Si+Al) ratio were selected for the research project and exchanged with a number of either monovalent and divalent cations. In this paper we describe a general picture of the changes which occur in the structure of phillipsite in response to the cation exchange either in terms of framework relaxation/contradion and cation migration, ion exchange selectivity and properties, and their prediction.