Loring John S, Simanova Anna A, Persson Per
Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden.
Langmuir. 2008 Jul 15;24(14):7054-7. doi: 10.1021/la800785u. Epub 2008 Jun 13.
Oxalate (C2O4 2-) acts synergistically on the dissolution of goethite (alpha-FeOOH) in the presence of siderophores that are secreted by plants and microorganisms to sequester iron. We report here the first in situ molecular-scale observations of synergistic ligand-promoted dissolution processes. We show that there are conditions under which oxalate promotes goethite dissolution, but dissolved Fe(III) concentrations do not increase because Fe(III)-oxalate complexes readsorb to the mineral surface. We demonstrate that these readsorbed Fe(III)-oxalate complexes are highly mobile, extremely reactive in the presence of uncomplexed siderophores, and responsible for the synergistic effects on the dissolution of goethite.
