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Understanding sorption mechanisms of uranium onto elemental iron, minerals and Shewanella putrefaciens surfaces in the presence of arsenicN’zau Umba-di-Mbudi, Clement 19 March 2010 (has links) (PDF)
The concomitant occurrence and reported discrepant behavior of uranium and arsenic in water bodies is a major health and environmental concern. This study combined batch and column experiments, hydrogeochemical simulations and XAFS spectroscopy to uncover the exchange mechanisms governing uranium fate between water and scrap metallic iron, minerals and Shewanella putrefaciens surfaces in the presence of arsenic. The main results suggest that both water chemistry and the solid phase composition influence uranium fate in the presence of arsenic. The importance of uranyl-arsenate species as a major control of uranium behavior in the presence of arsenic is shown. The toxicity of arsenic and the presence of nitrate are interpreted as limiting factors of the enzymatic reduction of both toxins. Besides, XANES fingerprinting and EXAFS modeling have confirmed precipitation/co-precipitation of uranyl-arsenates as a major mechanism controlling uranium behavior in the presence of arsenic.
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Understanding sorption mechanisms of uranium onto elemental iron, minerals and Shewanella putrefaciens surfaces in the presence of arsenicN’zau Umba-di-Mbudi, Clement 11 December 2009 (has links)
The concomitant occurrence and reported discrepant behavior of uranium and arsenic in water bodies is a major health and environmental concern. This study combined batch and column experiments, hydrogeochemical simulations and XAFS spectroscopy to uncover the exchange mechanisms governing uranium fate between water and scrap metallic iron, minerals and Shewanella putrefaciens surfaces in the presence of arsenic. The main results suggest that both water chemistry and the solid phase composition influence uranium fate in the presence of arsenic. The importance of uranyl-arsenate species as a major control of uranium behavior in the presence of arsenic is shown. The toxicity of arsenic and the presence of nitrate are interpreted as limiting factors of the enzymatic reduction of both toxins. Besides, XANES fingerprinting and EXAFS modeling have confirmed precipitation/co-precipitation of uranyl-arsenates as a major mechanism controlling uranium behavior in the presence of arsenic.
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