Study of the interaction between europium (III) and Bacillus subtilis: fixation sites, biosorption modeling and reversibility.
In order to elucidate the underlying mechanisms involved in the biosorption of metal ions, potentiometric titrations, complexation studies, and time-resolved laser-induced fluorescence spectroscopy (TRLFS) measurements were used to characterize the interaction between Eu(III) and Bacillus subtilis. The reversibility of the interaction between Eu(III) and Bacillus subtilis was studied by a cation-exchange technique using the Chelex resin. For complexation studies in the presence of 0.15 mol/l of NaCl, the metal ion, the biomass, concentrations and the pH were varied. The adsorption data were quantified by a surface complexation model without electrostatic term. The data on the Eu(III)/B.subtilis system at pH 5 were satisfactorily described by one site at which Eu(III) was bound through one carboxylic function of the bacteria. With increasing pH, another site should be considered, involving a phosphate-bound environment. This was partially confirmed by time-resolved laser-induced fluorescence spectroscopy. In addition to this, it was evidenced that the site availability was dependent on the nature of the cation, i.e., a proton or Eu(III). Finally, it was shown that, at pH 5, the Eu(III)/Bacillus subtilis equilibrium was reversible.
Markai
S
S
SUBATECH UMR 6457, Université de Nantes, Ecole des Mines, IN2P3/CNRS, Nantes, France.
Andrès
Y
Y
Montavon
G
G
Grambow
B
B
D000327:Adsorption; D001412:Bacillus subtilis / Q000378:metabolism*; D001665:Binding Sites; D018533:Biomass; D004785:Environmental Pollutants / Q000032:analysis; D005063:Europium / Q000032:analysis* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D019216:Metals, Heavy / Q000032:analysis / Q000737:chemistry; D008962:Models, Theoretical
D004785:Environmental Pollutants; D019216:Metals, Heavy; D005063:Europium