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Soil Science Society of America Journal Abstract -

Factors Affecting Distributions of Cations in Clay-Electrolyte Systems1


This article in SSSAJ

  1. Vol. 17 No. 3, p. 227-230
    Received: Jan 9, 1953

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  1. Moyle E. Harward and
  2. A. Mehlich2



Investigations were conducted on some factors which influence distributions of K and Ca in clay-electrolyte systems.

The method involved the additions of acids to variously base saturated suspensions of Utah bentonite and Kamec halloysite. The distributions of K and Ca were determined from an analysis of the supernatant liquid after equilibrium was obtained.

The results suggest that the effect of Ca-saturation upon the replacement of K is related to type of colloid and to the amount of acid added. When HCl in amounts greater than 0.09 symmetry were added to Utah bentonite systems, the amount of K in solution increased with Ca-saturation, reached a maximum and then decreased. The degree of Ca-saturation at which the maximum amount of K was in solution was dependent upon the amount of acid added to these systems.

Appreciable amounts of K and Ca were in solution when no electrolyte was added. Under these conditions K and Ca in solution increased with increasing degree of Ca-saturation and they were greater in Kamec halloysite than in Utah bentonite systems. When small amounts of acid were added, however, the amounts of K and Ca in solution were greater for the Utah bentonite than for the Kamec halloysite systems at low degrees of base saturation while the reverse was true at high degrees of saturation. The addition of small amounts of acid did not change the trend of K in solution increasing with Ca-saturation for both clays.

The influence of some partially ionized solution species upon the replacement of K was investigated by using acids with different dissociation constants. The data suggested that differences between acids will only be evident if the pH of the equilibrium solutions are below that at which the acids are ordinarily neutralized.

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