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This article in SSSAJ

  1. Vol. 26 No. 6, p. 541-544
    Received: Feb 8, 1962
    Accepted: Mar 1, 1962

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Isotopic Exchange of Potassium in an Illite under Equilibrium Conditions1

  1. M. E. Sumner and
  2. G. H. Bolt2



The kinetics of K exchange in an illite were studied using K42. The influence of various pretreatments was investigated, and a comparison was made between exchange with K42 under equilibrium conditions during 1 week and repeated extraction with 0.5 N NH4NO3 and 0.5 N NaNO3. Except for the samples containing 0.5 N CaCl2 the K42 exchange appeared to be very fast and no further increase could be observed during shaking from 6 hours up to 1 week.

Prolonged pretreatment with 0.5 N CaCl2 apparently caused an opening up of the clay lattice. The 0.5 N NH4-extraction following this treatment always removed considerably more K than was exchangeable against K42 under equilibrium conditions.

On the other hand, extraction with 0.5 N NaNO3 removed even less than was exchangeable against K42, indicating that part of the exchangeable K was still in interlattice positions.

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