Geometry and Dynamics of Intercalated Water in Na-Fluorhectorite Clay Hydrates

Abstract

Proton and deuterium NMR measurements are performed in Na-fluorhectorite powdered samples. The results are compared with NMR data from other 2:1 clays, and with the recent results of molecular simulations, they yield new information about the factors governing the geometry and dynamics of intercalated water in these materials. In the one-water layer regime, two different sites were identified, permitting us to elucidate the structure of interlamellar water. The role of proton exchange appears to be more pronounced in Na−Fht than in Na−vermiculite and is not limited to the 2WL regime. It appears to be promoted by a considerable amount of interlamellar water outside the hydration sphere of the cation.