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Competition effects in cation binding to humic acid: Conditional affinity spectra for fixed total metal concentration conditions

Competition effects in cation binding to humic acid: Conditional affinity spectra for fixed total metal concentration conditions
Competition effects in cation binding to humic acid: Conditional affinity spectra for fixed total metal concentration conditions
Information on the Pb and Cd binding to a purified Aldrich humic acid (HA) is obtained from the influence of different fixed total metal concentrations on the acid base titrations of this ligand. NICA (Non-Ideal Competitive Adsorption) isotherm has been used for a global quantitative description of the binding, which has then been interpreted by plotting the Conditional Affinity Spectra of the H+ binding at fixed total metal concentrations (CAScTM). This new physicochemical tool, here introduced, allows the interpretation of binding results in terms of distributions of proton binding energies. A large increase in the acidity of the phenolic sites as the total metal concentration increases, especially in presence of Pb, is revealed from the shift of the CAScTM towards lower affinities. The variance of the CAScTM distribution, which can be used as a direct measure of the heterogeneity, also shows a significant dependence on the total metal concentration. A discussion of the factors that influence the heterogeneity of the HA under the conditions of each experiment is provided, so that the smoothed pattern exhibited by the titration curves can be justified.
ADSORPTION ENERGY-DISTRIBUTION, LAURENTIDE FULVIC-ACID, ION-BINDING, HETEROGENEOUS SURFACES, SUBSTANCES, MODEL, COMPLEXATION, ISOTHERMS, DISTRIBUTIONS, SITES
0016-7037
5216-5227
David, Calin
65ae11f9-1835-4dee-8d8b-3675d2edf113
Mongin, Sandrine
45b71daa-4a96-435d-a95f-990a6ba6222f
Rey-Castro, Carlos
c9ba6881-700b-4331-8aed-5c0b1b401af8
Galceran, Josep
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Companys, Encarnacio
a3def73f-5b09-4154-b6a5-15934978923a
Luis Garces, Jose
76a73bf9-3079-4bba-96ae-4373227592c9
Salvador, Jose
b7f83ec6-90a3-4531-8e6a-90b6119497ed
Puy, Jaume
24644b39-bbea-4d50-b3c2-ef2d43408047
Cecilia, Joan
65a428a3-4410-4e19-880b-d015b1b6903c
Lodeiro, Pablo
f6c1011a-06d0-4095-bc45-2e15e9e492d0
Mas, Francesc
561cc2de-e12e-469c-bed3-4da66c3347e9
David, Calin
65ae11f9-1835-4dee-8d8b-3675d2edf113
Mongin, Sandrine
45b71daa-4a96-435d-a95f-990a6ba6222f
Rey-Castro, Carlos
c9ba6881-700b-4331-8aed-5c0b1b401af8
Galceran, Josep
16a2dff8-7389-4a70-8802-c208b54ebdfa
Companys, Encarnacio
a3def73f-5b09-4154-b6a5-15934978923a
Luis Garces, Jose
76a73bf9-3079-4bba-96ae-4373227592c9
Salvador, Jose
b7f83ec6-90a3-4531-8e6a-90b6119497ed
Puy, Jaume
24644b39-bbea-4d50-b3c2-ef2d43408047
Cecilia, Joan
65a428a3-4410-4e19-880b-d015b1b6903c
Lodeiro, Pablo
f6c1011a-06d0-4095-bc45-2e15e9e492d0
Mas, Francesc
561cc2de-e12e-469c-bed3-4da66c3347e9

David, Calin, Mongin, Sandrine, Rey-Castro, Carlos, Galceran, Josep, Companys, Encarnacio, Luis Garces, Jose, Salvador, Jose, Puy, Jaume, Cecilia, Joan, Lodeiro, Pablo and Mas, Francesc (2010) Competition effects in cation binding to humic acid: Conditional affinity spectra for fixed total metal concentration conditions. Geochimica et Cosmochimica Acta, 74 (18), 5216-5227. (doi:10.1016/j.gca.2010.06.023).

Record type: Article

Abstract

Information on the Pb and Cd binding to a purified Aldrich humic acid (HA) is obtained from the influence of different fixed total metal concentrations on the acid base titrations of this ligand. NICA (Non-Ideal Competitive Adsorption) isotherm has been used for a global quantitative description of the binding, which has then been interpreted by plotting the Conditional Affinity Spectra of the H+ binding at fixed total metal concentrations (CAScTM). This new physicochemical tool, here introduced, allows the interpretation of binding results in terms of distributions of proton binding energies. A large increase in the acidity of the phenolic sites as the total metal concentration increases, especially in presence of Pb, is revealed from the shift of the CAScTM towards lower affinities. The variance of the CAScTM distribution, which can be used as a direct measure of the heterogeneity, also shows a significant dependence on the total metal concentration. A discussion of the factors that influence the heterogeneity of the HA under the conditions of each experiment is provided, so that the smoothed pattern exhibited by the titration curves can be justified.

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More information

Published date: 15 September 2010
Keywords: ADSORPTION ENERGY-DISTRIBUTION, LAURENTIDE FULVIC-ACID, ION-BINDING, HETEROGENEOUS SURFACES, SUBSTANCES, MODEL, COMPLEXATION, ISOTHERMS, DISTRIBUTIONS, SITES
Organisations: Ocean Biochemistry & Ecosystems

Identifiers

Local EPrints ID: 354268
URI: http://eprints.soton.ac.uk/id/eprint/354268
ISSN: 0016-7037
PURE UUID: 3f05ff9a-4123-4d67-9161-181040fcc1dd

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Date deposited: 05 Jul 2013 08:34
Last modified: 14 Mar 2024 14:16

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Contributors

Author: Calin David
Author: Sandrine Mongin
Author: Carlos Rey-Castro
Author: Josep Galceran
Author: Encarnacio Companys
Author: Jose Luis Garces
Author: Jose Salvador
Author: Jaume Puy
Author: Joan Cecilia
Author: Pablo Lodeiro
Author: Francesc Mas

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