Effect of hydroxamate siderophores on Fe release and Pb(II) adsorption by goethite
Hydroxamate siderophores are biologically-synthesized, Fe(III)-specific ligands which are common in soil environments. The authors report an investigation of their adsorption by the iron oxyhydroxide, goethite; their influence on goethite dissolution kinetics; and their ability to affect Pb(II) adsorption by the goethite surface. The siderophores used were desferrioxamine B (DFO-B), a fungal siderophore, and desferrioxamine D{sub 1}, an acetyl derivative of DFO-B (DFO-D1). Siderophore adsorption isotherms yielded maximum surface concentrations of 1.5 (DFO-B) or 3.5 (DFO-D1) {micro}mol/g at pH 6.6, whereas adsorption envelopes showed either cation-like (DFO-B) or ligand-like (DFO-D1) behavior. Above pH 8, the adsorbed concentrations of both siderophores were similar. The dissolution rate of goethite in the presence of 240 {micro}M DFO-B or DFO-D1 was 0.02 or 0.17 {micro}mol/g hr, respectively. Comparison of these results with related literature data on the reactions between goethite and acetohydroxamic acid, a monohydroxamate ligand, suggested that the three hydroxamate groups in DFO-D1 coordinate to Fe(III) surface sites relatively independently. The results also demonstrated a significant depleting effect of 240 {micro}M DFO-B or DFO-D1 on Pb(II) adsorption by goethite at pH {gt} 6.5, but there was no effect of adsorbed Pb(II) on the goethite dissolution rate.
- Research Organization:
- Univ. of California, Berkeley, CA (US)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG03-96ER14667
- OSTI ID:
- 20003961
- Journal Information:
- Geochimica et Cosmochimica Acta, Vol. 63, Issue 19-20; Other Information: PBD: Oct 1999; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
Similar Records
A spectroscopic study of the effects of a microbial siderophore on Pb adsorption to kaolinite
Evidence for Ligand Hydrolysis and Fe(III) Reduction in the Dissolution of Goethite by Desferrioxamine-B