Original scientific paper

Determination of the Ion Adsorption by the Radioactive Tracer Technique.* IV. Coagulation of Negative AgJ Sols by Adding Mixtures of Different Valency Cations and the Cation Adsorption

M. J . Herak ; Department of Radiochemistry, Institute »Ruder Boskovic« and Laboratory of Physical Chemistry , Faculty of Science, University of Zagreb , Zagreb, Croatia, Yugoslavia
M. Mirnik ; Department of Radiochemistry, Institute »Ruder Boskovic« and Laboratory of Physical Chemistry , Faculty of Science, University of Zagreb , Zagreb, Croatia, Yugoslavia

Abstract

The coagulation value of Co2+ for neg ative Ag! increases w ith
increasing co1I1<;:entrations of Na+, while that of N a+ decreases only
slightly with increasing concentrations of Co 2+. If an ion of higher
valency (Co+2 or Eua+)· is present in concentration higher than its
coagulation value, the lower valency i·ons (Li', Na+, K + or
Co2+) exhibit a stablizing action evidenced by a minimum in
turbidity curves at concentrations somewhat lower than the coagulaitiion values of the lat t er tons. Electron microscope investigat~on shows that for prolonged time intervals the particles of the systems defined by the; mentioned ·minima are not coagulated, while those of the systems with high turbidities are agglomerates of many primary particles. Adso.rption measurements of coagulating counter ions by the radioactive tracer technique prove that the same ion
exchange mechanism, which was ob served earlier at concentrations
higher than the coagulation value, is a lso valid for concentrations
at which the stabilization with lower valent ions was observed.
Thus the same thermodynamic equations are valid in concentrations
higher and lower than the coagulation value.

Keywords

Hrčak ID:

208394

URI

https://hrcak.srce.hr/208394

Publication date:

25.11.1962.

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