Affiliation:
1. Helmholtz Zentrum Dresden-Rossendorf e. V., Institute of Resource Ecology, P.O.Box 510119, D-01314 Dresden, Germany
Abstract
Abstract
The ability of Euglena mutabilis cells – a unicellular protozoan with a flexible pellicle, which is typically found in acid
mine drainage (AMD) environments – to bioaccumulate uranium under acid conditions was studied in batch sorption experiments at pH 3
and 4 using Na2SO4 and NaClO4 as background media. It was found that axenic cultures of Euglena mutabilis
Schmitz were able to bioaccumulate in 5 days 94.9 to 99.2% of uranium from a 1 · 10
–5 mol/L uranium solution
in perchlorate medium and 95.1 to 95.9% in sodium sulfate medium, respectively.
The speciation of uranium in solution and uranium bioaccumulated by Euglena mutabilis cells, were studied by laser induced
fluorescence spectroscopy (LIFS). The LIFS investigations showed that the uranium speciation in the NaClO4 systems was dominated
by free uranyl(VI) species and that the UO2SO4 species was dominating in the Na2SO4 medium. Fluorescence spectra of
the bioaccumulated uranium revealed that aqueous uranium binds to carboxylic and/or (organo)phosphate groups located on the euglenid
pellicle or inside the Euglena mutabilis cells.
Reduced uranium immobilization rates of 0.93 – 1.43 mg uranium per g Euglena mutabilis biomass were observed in
similar experiments, using sterile filtrated AMD waters containing, 4.4 · 10
–5 mol/L uranium. These lower rates were attributed
to competition with other cations for available sorption sites. Additional LIFS measurements, however, showed that the speciation of
the bioaccumulated uranium by the Euglena mutabilis cells was found to be identical with the uranium speciation found in the
bioaccumulation experiments carried out in Na2SO4 and NaClO4 media.
The results indicate that Euglena mutabilis has the potential to immobilize aqueous uranium under acid condition and thus may
be used in future as promising agent for immobilizing uranium in low pH waste water environments.
Subject
Physical and Theoretical Chemistry
Cited by
4 articles.
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