Abstract: The electron microprobe has been used to analyse mixtures of fine-grained silicates such as clay minerals in order to determine directly how cations distribute themselves between mixtures of two fine-grained ion-exchanging materials in pure water and in dilute solutions.
Cation distributions have been determined for mixtures of: a zeolite, faujasite, and the clay mineral in an Arizona bentonite; the clay mineral in an Arizona bentonite and hectorite; and three synthetic beidellites of varying charge density.
Distributions have been found for varying ratios of Ca to K ions in the suspensions. The results for the faujasite-bentonite mixture show complex behavior and exhibit curves with maxima and minima. For the system bentonite-hectorite most of the Ca goes to the montmorillonite in the bentonite. For the mixture of synthetic beidellites, the results are rather confusing but it appears that the calcium is more associated with the beidellite with the highest exchange capacity. In all these systems, hydrolysis takes place and the hydronium ion plays a part in determining the equilibrium.