title: Reduction and Accumulation of Gold(III) byMedicago sativaAlfalfa Biomass: X-ray Absorption Spectroscopy, pH, and Temperature Dependence.
abstract: We report herein the use ofMedicago sativaalfalfa shoot biomass for the removal of gold from aqueous solutions. The accumulation process involves the reduction of Au(III) to colloidal Au(0) and is shown to increase at elevated temperatures and at lower pH. X-ray absorption spectroscopy (XAS) was used to determine that gold(III) was reduced to form gold(0) colloids, which varied in size depending on the pH of the initial solution. The gold cluster radius was 6.2 ± 1 Å at pH 5 and 9.0 ± 1 Å at pH 2. Our findings indicate that essentially another layer of gold atoms was deposited onto the colloid surface at pH 2. Possible mechanisms of bioreduction and accumulation are discussed.
authors.affiliation: University of Texas at El Paso.
authors.forename: J L
authors.initials: JL
authors.lastname: Gardea-Torresdey
authors.affiliation: University of Texas at El Paso.
authors.forename: K J
authors.initials: KJ
authors.lastname: Tiemann
authors.affiliation: University of Texas at El Paso.
authors.forename: G
authors.initials: G
authors.lastname: Gamez
authors.affiliation: University of Texas at El Paso.
authors.forename: K
authors.initials: K
authors.lastname: Dokken
authors.affiliation: Universidad de Guanajuato.
authors.forename: Irene
authors.initials: I
authors.lastname: Cano-Aguilera
authors.affiliation: University of Arizona.
authors.forename: Lars R
authors.initials: LR
authors.lastname: Furenlid
authors.affiliation: Brookhaven National Laboratory.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Renner