title: Bioreduction and precipitation of uranium in ionic liquid aqueous solution by Clostridium sp.
abstract: The ionic liquids, 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6], N-ethylpyridiniumtrifluoroacetate [EtPy][CF3COO] and N-ethylpyridiniumtetrafluoroborate [EtPy][BF4], affected the reduction and precipitation of uranium by Clostridium sp. to a varying degree. Characterization of uranium association with the ionic liquids showed that uranium formed a monodentate complex with the anion BF4(-) and PF6(-) of [EtPy][BF4] and [BMIM][PF6], respectively; and a bidentate complex with carboxylate of [EtPy][CF3COO]. Bioreduction of U(VI) was influenced by the type of complex formed: monodentate complexes were readily reduced whereas the bidentate complex of U(VI) with [CF3COO] was recalcitrant. [EtPy][BF4] affected the rate and extent of precipitation of the reduced uranium; at higher concentration the reduced U(IV) remained in the solution phase. The results suggest that by tuning the properties of ionic liquids they may be valuable candidates for uranium biotreatment.
authors.affiliation: Department of Chemistry and Environmental Science, New Jersey Institute of Technology, New York, NJ 07104, USA. zhangchengdong@nankai.edu.cn
authors.forename: C
authors.initials: C
authors.lastname: Zhang
authors.forename: C J
authors.initials: CJ
authors.lastname: Dodge
authors.forename: S V
authors.initials: SV
authors.lastname: Malhotra
authors.forename: A J
authors.initials: AJ
authors.lastname: Francis
mesh_terms: D001673:Biodegradation, Environmental / Q000187:drug effects; D011232:Chemical Precipitation; D003013:Clostridium / Q000187:drug effects / Q000378:metabolism*; D007093:Imidazoles / Q000494:pharmacology; D052578:Ionic Liquids / Q000494:pharmacology*; D007700:Kinetics; D011726:Pyridinium Compounds / Q000494:pharmacology; D012996:Solutions; D014501:Uranium / Q000302:isolation & purification / Q000378:metabolism*; D014875:Water Pollutants, Radioactive / Q000302:isolation & purification / Q000378:metabolism*; D056928:X-Ray Absorption Spectroscopy
chemical_list: C412621:1-butyl-3-methylimidazolium hexafluorophosphate; D007093:Imidazoles; D052578:Ionic Liquids; D011726:Pyridinium Compounds; D012996:Solutions; D014875:Water Pollutants, Radioactive; C011815:ethylpyridinium; D014501:Uranium