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Reactions Affecting Cation Exchange Kinetics in Vermiculite
Author(s) -
Klobe W. D.,
Gast R. G.
Publication year - 1967
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1967.03615995003100060014x
Subject(s) - vermiculite , chemistry , fixation (population genetics) , saturation (graph theory) , ion exchange , caesium , kinetics , isotope , mineralogy , analytical chemistry (journal) , inorganic chemistry , nuclear chemistry , chromatography , geology , ion , organic chemistry , mathematics , paleontology , biochemistry , physics , combinatorics , quantum mechanics , gene
Strong retention of cations, commonly referred to as fixation, was studied using Cs and Sr exchange reactions with Montana vermiculite. Fixation was defined as the property of an exchanger to retain cations in a state such that they are not available for rapid isotopic exchange in a well‐stirred system. Efforts were directed toward qualitatively determining some of the conditions under which fixation occurs. Equations were derived to calculate fixation using isotopic equilibrium values attained with separate aliquots of carrier‐free isotope. Cesium fixation occurred in all size fractions of vermiculite ranging from 40–20 mesh through < 0.2 µ upon addition of 1 symmetry stable CsCl. The amount of 134 Cs fixed at this Cs level depended on the sequence of adding separate aliquots of isotope and the corresponding stable salt, and appeared to be caused by lattice collapse. The amount of Cs fixed increased with increasing additions of CsCl. However, when Cs saturation of the vermiculite exchange capacity exceeded 4.5%, the fraction of sorbed Cs that became fixed was relatively constant. A plot of Cs fixation vs. percent Cs saturation of the exchange capacity indicated that fixation was independent of time over an interval of 4 months. In contrast to the Cs results, Sr was always readily exchangeable, with no evidence of lattice collapse.