Other
Scientific paper
Aug 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011gecoa..75.4426s&link_type=abstract
Geochimica et Cosmochimica Acta, Volume 75, Issue 16, p. 4426-4440.
Other
Scientific paper
One option for immobilizing uranium present in subsurface contaminated groundwater is in situ bioremediation, whereby dissimilatory metal-reducing bacteria and/or sulfate-reducing bacteria are stimulated to catalyze the reduction of soluble U(VI) and precipitate it as uraninite (UO2). This is typically accomplished by amending groundwater with an organic electron donor. It has been shown, however, that once the electron donor is entirely consumed, Fe(III) (hydr)oxides can reoxidize biogenically produced UO2, thus potentially impeding cleanup efforts. On the basis of published experiments showing that such reoxidation takes place even under highly reducing conditions (e.g., sulfate-reducing conditions), thermodynamic and kinetic constraints affecting this reoxidation are examined using multicomponent biogeochemical simulations, with particular focus on the role of sulfide and Fe(II) in solution. The solubility of UO2 and Fe(III) (hydr)oxides are presented, and the effect of nanoscale particle size on stability is discussed. Thermodynamically, sulfide is preferentially oxidized by Fe(III) (hydr)oxides, compared to biogenic UO2, and for this reason the relative rates of sulfide and UO2 oxidation play a key role on whether or not UO2 reoxidizes. The amount of Fe(II) in solution is another important factor, with the precipitation of Fe(II) minerals lowering the Fe+2 activity in solution and increasing the potential for both sulfide and UO2 reoxidation. The greater (and unintuitive) UO2 reoxidation by hematite compared to ferrihydrite previously reported in some experiments can be explained by the exhaustion of this mineral from reaction with sulfide. Simulations also confirm previous studies suggesting that carbonate produced by the degradation of organic electron donors used for bioreduction may significantly increase the potential for UO2 reoxidation through formation of uranyl carbonate aqueous complexes.
Belding Eileen
Ginn Tim R.
Issarangkun Montarat
Peyton Brent M.
Sani Rajesh K.
No associations
LandOfFree
Biogenic uraninite precipitation and its reoxidation by iron(III) (hydr)oxides: A reaction modeling approach does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Biogenic uraninite precipitation and its reoxidation by iron(III) (hydr)oxides: A reaction modeling approach, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Biogenic uraninite precipitation and its reoxidation by iron(III) (hydr)oxides: A reaction modeling approach will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1674177