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Boyd, G.E.* ; Bunzl, K.W.

Selective binding of ions by polyelectrolyte gels. The volume change criterion.

J. Am. Chem. Soc. 96, 2054-2058 (1974)
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The volume changes, ΔV, which accompany the selective binding of ions in ion-exchange reactions at 25° between aqueous electrolyte mixtures and polyelectrolyte gels were measured in an attempt to establish the range of applicability of the Katchalsky and the Rice-Harris theories. The ΔV for the exchange of singly charged ions in lightly cross-linked polystyrene type strong-acid or strong-base ion-exchanger gels were small and positive or negative depending on the nature of the ions. Large, positive volume changes were observed with multiply charged cations. In general, ΔV became more positive with increased gel cross linking and with the strength of binding as measured by the decrease in the standard free energy, ΔG°, in the ion-exchange reaction. Four types of ion-binding processes were distinguished: (a) field binding; (b) site binding via ion-pair formation; (c) structure-enforced binding; and (d) charge-transfer binding. Multiply charged cations (i.e., Ca2+, Ba2+, La3+, Th4+) were selectively bound as ion pairs in all gels. Field binding could be inferred only for the selective uptake of singly charged cations in the lightly cross-linked gel.
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Publication type Article: Journal article
Document type Scientific Article
ISSN (print) / ISBN 0002-7863
e-ISSN 1520-5126
Quellenangaben Volume: 96, Issue: 7, Pages: 2054-2058 Article Number: , Supplement: ,
Publisher American Chemical Society (ACS)
Reviewing status Peer reviewed