Showing papers by "Jeremy B. Fein published in 2013"
TL;DR: Results indicate that the extent of U( VI) reduction is controlled by dissolution of the HUP phase, suggesting that the metal-reducing bacteria transfer electrons to the dissolved or bacterially adsorbed U(VI) species formed after HUP dissolution, rather than to solid-phase U(II) in the Hup mineral.
Abstract: The mobility of uranium (U) in subsurface environments is controlled by interrelated adsorption, redox, and precipitation reactions. Previous work demonstrated the formation of nanometer-sized hydrogen uranyl phosphate (abbreviated as HUP) crystals on the cell walls of Bacillus subtilis, a non-UVI-reducing, Gram-positive bacterium. The current study examined the reduction of this biogenic, cell-associated HUP mineral by three dissimilatory metal-reducing bacteria, Anaeromyxobacter dehalogenans strain K, Geobacter sulfurreducens strain PCA, and Shewanella putrefaciens strain CN-32, and compared it to the bioreduction of abiotically formed and freely suspended HUP of larger particle size. Uranium speciation in the solid phase was followed over a 10- to 20-day reaction period by X-ray absorption fine structure spectroscopy (XANES and EXAFS) and showed varying extents of UVI reduction to UIV. The reduction extent of the same mass of HUP to UIV was consistently greater with the biogenic than with the abiotic m...
78 citations
TL;DR: In this paper, a thermodynamically-based surface complexation model was adapted to describe experimental adsorption data under high ionic strength conditions where traditional corrections for aqueous ion activity are invalid.
32 citations
TL;DR: In this paper, the authors measured the adsorption of aqueous uranium [U(VI)] onto Shewanella oneidensis MR-1 with different initial concentrations of NaHCO3.
17 citations
TL;DR: In this paper, the authors investigate the effect of secondary precipitates such as Np 2 O 5 (s) on aqueous neptunium(V) concentrations.
9 citations