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Radiochimica Acta

International Journal for chemical aspects of nuclear science and technology

Ed. by Qaim, Syed M.

12 Issues per year

IMPACT FACTOR 2012: 1.373
5-year IMPACT FACTOR: 1.424
Rank 6 out of 34 in category Nuclear Science & Technology in the 2012 Thomson Reuters Journal Citation Report/Science Edition

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Bio-sorption of neptunium(V) by Pseudomonas fluorescens

W. Songkasiri / D. T. Reed / B. E. Rittmann

Citation Information: Radiochimica Acta. Volume 90, Issue 9-11/2002, Pages 785–789, ISSN (Print) 0033-8230, DOI: 10.1524/ract.2002.90.9-11_2002.785, September 2009

Publication History

Received:
September 10, 2001
Accepted:
April 11, 2002
Published Online:
2009-09-25

Summary

The bio-sorption of neptunyl (NpO2+) by Pseudomonas fluorescens was investigated. The overall goals of this research are to identify key interactions between neptunium and soil bacteria and to model these effects under subsurface-related conditions. Neptunyl, which is generally thought to be non-sorptive, was significantly sorbed under all conditions studied. At initial neptunyl concentrations of 4.75 µM and pH = 7, as much as 85% of the neptunium was sorbed under aerobic conditions. Kinetic studies show that neptunyl was sorbed rapidly within the first 15 minutes. The extent of sorption also increased with pH. In all cases, the sorbed neptunium was shown to be NpO2+ by X-ray absorption near edged spectroscopy (XANES) analysis, confirming that there was no reduction to Np(IV) under the conditions of our experiment. The sorption data were modeled using Langmuir and Freundlich isotherms. A comparison of the two approaches showed a significantly better fit for the Freundlich isotherm, and the Freundlich parameter values suggest interactions between sorbed NpO2+ molecules. These data show that bio-sorption, even for neptunyl, has a significant role in defining the speciation of neptunium and, hence, its overall mobility in the subsurface.

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