Bonding of Calcium and Potassium by Vermiculite and Kaolinite Clays as Affected by H-clay Addition1
- A. S. Baweja and
- E. O. McLean2
The < 2 µm fraction of Libby vermiculite and Peerless kaolinite was separated and H-saturated by resin treatment. The H-clay suspensions were immediately saturated with either Ca or K by addition of the respective hydroxides. Six reciprocal Ca-K saturations of each clay were prepared by mixing the Ca- and K-clays in appropriate amounts. Increments of H-clay were added to lower the base saturation and thereby inactivate the pH-dependent charges. Radioisotopes, 45Ca and 86Rb, were used as tracers for Ca and K, respectively. Two-phase Donnan-type systems were prepared and equilibrated for 23 days. Radioactivity in both phases was then assayed and the amounts of Ca and K retained in the suspension phases of the two clay systems computed.
The pH-dependent fraction of the total CEC was 6.9 and 18.0% for vermiculite and kaolinite, respectively. Additions of H-clay increased the bonding of both Ca and K as indicated by greater clay-phase retention. However, maximum retention of the cations at all Ca-K saturation ratios did not occur when the amounts of H-clay added equaled the pH-dependent charge fraction of the clay as had occurred with bentonite and illite.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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