title: Effect of Natural Organic Matter on Plutonium Sorption to Goethite.
abstract: The effect of citric acid (CA), desferrioxamine B (DFOB), fulvic acid (FA), and humic acid (HA) on plutonium (Pu) sorption to goethite was studied as a function of organic carbon concentration and pH using batch sorption experiments at 5 mgC·L-1and 50 mgC·L-1natural organic matter (NOM), 10-9-10-10M238Pu, and 0.1 g·L-1goethite concentrations, at pH 3, 5, 7, and 9. Low sorption of ligands coupled with strong Pu complexation decreased Pu sorption at pH 5 and 7, relative to a ligand-free system. Conversely, CA, FA, and HA increased Pu sorption to goethite at pH 3, suggesting ternary complex formation or, in the case of humic acid, incorporation into HA aggregates. Mechanisms for ternary complex formation were characterized by Fourier transform infrared spectroscopy in the absence of Pu. CA and FA demonstrated clear surface interactions at pH 3, HA appeared unchanged suggesting HA aggregates had formed, and no DFOB interactions were observed. Plutonium sorption decreased in the presence of DFOB (relative to a ligand free system) at all pH values examined. Thus, DFOB does not appear to facilitate formation of ternary Pu-DFOB-goethite complexes. At pH 9, Pu sorption in the presence of all NOM increased relative to pH 5 and 7; speciation models attributed this to Pu(IV) hydrolysis competing with ligand complexation, increasing sorption. The results indicate that in simple Pu-NOM-goethite ternary batch systems, NOM will decrease Pu sorption to goethite at all but particularly low pH conditions.
authors.affiliation: Department of Environmental Engineering and Earth Sciences, Clemson University , Clemson, South Carolina 29634, United States.
authors.forename: Nathan A
authors.initials: NA
authors.lastname: Conroy
authors.affiliation: Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States.
authors.forename: Mavrik
authors.initials: M
authors.lastname: Zavarin
authors.affiliation: Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States.
authors.forename: Annie B
authors.initials: AB
authors.lastname: Kersting
authors.affiliation: Department of Environmental Engineering and Earth Sciences, Clemson University , Clemson, South Carolina 29634, United States.
authors.forename: Brian A
authors.identifier: 0000-0003-0423-0180
authors.initials: BA
authors.lastname: Powell
mesh_terms: D000327:Adsorption; D002244:Carbon; D003676:Deferoxamine; D006812:Humic Substances; D006863:Hydrogen-Ion Concentration; D011005:Plutonium / Q000737:chemistry*
chemical_list: D006812:Humic Substances; D011005:Plutonium; D002244:Carbon; D003676:Deferoxamine