Nanoscale Encapsulation : The Structure of Cations in Hydrophobic Microporous Aluminosilicates

Abstract
Hydrophobic microporous aluminosilicates created by the modification of zeolites and clays are currently being investigated as storage media for hazardous cations. Addition of an organic monolayer to the surface of an aluminosilicate after introduction of an ion into the zeolite or clay reduces the interaction of water with the material. The resultant systems are approximately 20 times more resistant to leaching of the stored ion than the unmodified ion-exchanged materials. XAS spectra demonstrate that byproducts from the organic modifier can complex with the encapsulated cation. This complexation can result in a decreased affinity of the cation for the aluminosilicate matrix. Changing the organic modifier eliminates this problem. XAS spectra also indicate that the reactivity and subsequent speciation of the encapsulated ion alters upon application of the hydrophobic layer.