Please use this identifier to cite or link to this item:
Title: Effect of Dunaliella tertiolecta organic exudates on the Fe(II) oxidation kinetics in seawater
Authors: González, A. G. 
Santana-Casiano, J. M. 
González-Dávila, M. 
Pérez-Almeida, N. 
Suárez De Tangil, M. 
UNESCO Clasification: 2510 Oceanografía
251002 Oceanografía química
Keywords: Dunaliella tertiolecta
Issue Date: 2014
Project: Estudio Del Comportamiento Químico Del Hierro en El Medio Marino en Presencia de Compuestos Orgánicos de Origen Fitoplanctónico 
Journal: Environmental science & technology 
Abstract: The role played by the natural organic ligands excreted by the green algae Dunaliella tertiolecta on the Fe(II) oxidation rate constants was studied at different stages of growth. The concentration of dissolved organic carbon increased from 2.1 to 7.1 mg L(-1) over time of culture. The oxidation kinetics of Fe(II) was studied at nanomolar levels and under different physicochemical conditions of pH (7.2-8.2), temperature (5-35 °C), salinity (10-37), and dissolved organic carbon produced by cells (2.1-7.1 mg L(-1)). The experimental rate always decreased in the presence of organic exudates with respect to that in the control seawater. The Fe(II) oxidation rate constant was also studied in the context of Marcus theory, where ΔG° was 39.31-51.48 kJ mol(-1). A kinetic modeling approach was applied for computing the equilibrium and rate constants for Fe(II) and exudates present in solution, the Fe(II) speciation, and the contribution of each Fe(II) species to the overall oxidation rate constant. The best fit model took into account two acidity equilibrium constants for the Fe(II) complexing ligands with pKa,1=9.45 and pKa,2=4.9. The Fe(II) complexing constants were KFe(II)-LH=3×10(10) and KFe(II)-L=10(7), and the corresponding computed oxidation rates were 68±2 and 36±8 M(-1) min(-1), respectively.
ISSN: 0013-936X
DOI: 10.1021/es5013092
Source: Environmental Science and Technology [ISSN 0013-936X], v. 48 (14), p. 7933-7941
Appears in Collections:Artículos
Show full item record

Google ScholarTM




Export metadata

Items in accedaCRIS are protected by copyright, with all rights reserved, unless otherwise indicated.