XPS AND XANES STUDIES OF URANIUM REDUCTION BY CLOSTRIDIUM SP

Citation
Aj. Francis et al., XPS AND XANES STUDIES OF URANIUM REDUCTION BY CLOSTRIDIUM SP, Environmental science & technology, 28(4), 1994, pp. 636-639
Citations number
31
Categorie Soggetti
Environmental Sciences","Engineering, Environmental
ISSN journal
0013936X
Volume
28
Issue
4
Year of publication
1994
Pages
636 - 639
Database
ISI
SICI code
0013-936X(1994)28:4<636:XAXSOU>2.0.ZU;2-#
Abstract
Speciation of uranium in cultures of Clostridium sp. by X-ray absorpti on near-edge spectroscopy (XANES) at the National Synchrotron Light So urce and by X-ray photoelectron spectroscopy (XPS) showed that U(VI) w as reduced to U(IV). In addition to U(IV), a lower oxidation state of uranium, most probably U(III), was detected by XANES in the bacterial cultures. Reduction of uranium occurred only in the presence of growin g or resting cells. Organic acid metabolites, the extracellular compon ents of the culture medium, and heat-killed cells failed to reduce ura nium under anaerobic conditions. The addition of uranyl acetate or ura nyl nitrate (> 210 mu M U) to the culture medium retarded the growth o f the bacteria as evidenced by an increase in the lag period before re sumption of growth, by decreases in turbidity, and in the total produc tion of gas and organic acid metabolites. These results show that uran ium in wastes can be stabilized by the action of anaerobic bacteria.