title: Adsorption of Pb(ll) and Eu(III) by oxide minerals in the presence of natural and synthetic hydroxamate siderophores.
abstract: Trihydroxamate siderophores have been proposed for use as mediators of actinide and heavy metal mobility in contaminated subsurface zones. These microbially produced ligands, common in terrestrial and marine environments, recently have been derivatized synthetically to enhance their affinity for transuranic metal cations. However, the interactions between these synthetic derivative and adsorbed trace metals have not been characterized. In this paper we compare a natural siderophore, desferrioxamine-B (DFO-B), with its actinide-specific catecholate derivative, N-(2,3-dihydroxy-4-(methylamido)benzoyl)desferrioxamine-B (DFOMTA), as to their effect on the adsorption of Pb(II) and Eu(III) by goethite and boehmite. In the presence of 240 microM DFO-B, a strongly depleting effect on Eu(III) adsorption by goethite and boehmite occurred above pH 6. By contrast, almost total removal of Eu(III) from solution in the neutral to slightly acidic pH range was observed in the presence of either 10 or 100 microM DFOMTA, due primarilyto the formation of metal-DFOMTA precipitates. Addition of DFOMTA caused an increase in Pb(II) adsorption by goethite below pH 5, but a decrease above pH 5, such that the Pb(II) adsorption edge in the presence of DFOMTA strongly resembled the DFOMTA adsorption envelope, which showed a maximum near pH 5 and decreasing adsorption toward lower and higher pH.
authors.affiliation: Division of Ecosystem Sciences, University of California, Berkeley 94720-3110, USA. stephan.kraemer@ito.umnw.ethz.ch
authors.forename: Stephan M
authors.initials: SM
authors.lastname: Kraemer
authors.forename: Jide
authors.initials: J
authors.lastname: Xu
authors.forename: Kenneth N
authors.initials: KN
authors.lastname: Raymond
authors.forename: Garrison
authors.initials: G
authors.lastname: Sposito
mesh_terms: D000327:Adsorption; D001682:Biological Availability; D011232:Chemical Precipitation; D004785:Environmental Pollutants / Q000032:analysis; D005063:Europium / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006877:Hydroxamic Acids / Q000737:chemistry*; D058085:Iron Compounds / Q000737:chemistry; D007854:Lead / Q000032:analysis / Q000737:chemistry*; D008670:Metals / Q000737:chemistry; D008903:Minerals; D010087:Oxides / Q000737:chemistry; D017262:Siderophores / Q000737:chemistry*; D014131:Trace Elements
chemical_list: D004785:Environmental Pollutants; D006877:Hydroxamic Acids; D058085:Iron Compounds; D008670:Metals; D008903:Minerals; D010087:Oxides; D017262:Siderophores; D014131:Trace Elements; C094886:goethite; D007854:Lead; D005063:Europium