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Título:
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Effective affinity distribution for the binding of metal Ions to a generic fulvic acid in natural waters
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Autor/a:
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Rey Castro, Carlos; Mongin, Sandrine; Huidobro Redondo, César; David, Calin; Salvador, José; Garcés, Josep Lluís; Galceran i Nogués, Josep; Mas i Pujadas, Francesc; Puy Llorens, Jaume
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Notas:
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The effective distribution of affinities (Conditional Affinity
Spectrum, CAS) seen by ametal ion bindingto a humic substance
under natural water conditions is derived and discussed
within the NICA-Donnan model. Analytical expressions for
the average affinity of these distributions in general multi-ion
mixtures are reported here for the first time. These expressions
enable a simple evaluation of the effect of all interfering
cations on the affinity distribution of a given one. We illustrate
this methodology by plotting the affinity spectra of a generic
fulvic acidfor14 different cationsinthe presence ofmajorinorganic
ions and trace metals at pH and concentration values
representative of a river water. The distribution of occupied
sites andtheir average affinity atthetypicalfreshwater conditions
are also reported for each ion. The CAS allows us to distinguish
three groups of cations: (a) Al, H, Pb, Hg, and Cr, which are
preferentially bound to the phenolic sites of the fulvic ligand; (b)
Ca, Mg, Cd, Fe(II), and Mn, which display a greater effective
affinityfor carboxylic sites, in contrastto what would be expected
from their individual complexation parameters; and (c) Fe(III),
Cu, Zn, and Ni, for which phenolic and carboxylic distributions
are overlapped.
We gratefully acknowledge support of this research by the Spanish Ministry of Education and Science (Projects CTQ2006-14385 and CTM2006-13583) and from the “Comissionat d’Universitats i Recerca de la Generalitat de Catalunya”. S. Mongin was supported by an FPI-MEC grant from the Spanish Government. |
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Derechos:
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(c) American Chemical Society, 2009
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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