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Título:
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Competitive Cd2+/H+ complexation to polyacrylic acid described by the stepwise and intrinsic stability constants
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Autor/a:
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Calin, David; Companys Ferran, Encarnació; Galceran i Nogués, Josep; Garcés, Josep Lluís; Mas i Pujadas, Francesc; Rey Castro, Carlos; Salvador, José; Puy Llorens, Jaume
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Notas:
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Stepwise constants can be used to describe competitive proton and metal binding to macromolecules with a
large number of sites. With the aim of accessing information on the microscopic binding model, we report
an expression that connects the stepwise constants to the site-specific metal constants. This expression holds
for a very general complexation model including heterogeneity, interactions, and chelate complexation.
Assuming bidentate binding of the Cd ions to adjacent carboxylate groups in poly(acrylic acid), stepwise and
intrinsic stability constants for proton and cadmium binding were estimated from the experimental data. Intrinsic
values were split into specific and electrostatic contributions (by means of the Poisson
-
Boltzmann equation
under cylindrical geometry). Free of the electrostatic contribution, the remaining Cd binding energy showed
almost no dependence on the coverage and ionic strength, and the corresponding average values allowed for
a reasonable reproduction of raw binding data. Small systematic discrepancies from the homogeneous behavior
are critically discussed.
The authors gratefully acknowledge support of this research by the Spanish Ministry of Education and Science (Projects CTQ2006-14385 and CTM2006-13583) and by the “Comissionat d’Universitats i Recerca de la Generalitat de Catalunya” (2005SGR00616). |
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Materia(s):
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-Química
-Protons |
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Derechos:
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(c) American Chemical Society, 2008
info:eu-repo/semantics/restrictedAccess |
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Tipo de documento:
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article
publishedVersion |
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Editor:
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American Chemical Society
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