Selective biosorption of thorium ions by an immobilized mycobacterial biomass

International audienceno abstrac

Adsorption of several actinide (th-u) and lanthanide (la-eu-yb) ions by myobacterium smegmatis

International audienceAdsorption measurements of several actinide [thorium (Th), uranium (U)] and lanthanide [lanthanum (La), europium (Eu), ytterbium (Yb)] cations by Mycobacterium smegmatis showed that sorption kinetics followed a three-phase pattern. For 5% (w/w) bacterial suspensions at pH 1, maximum cation biosorption per gram dry biomass corresponded to 170 mumol Th4+ and 187 mumol UO22+. Adsorption of all cations studied obeyed the Brunauer-Emmett-Teller isotherm, which assumes multilayer binding at constant energy. Plots for the Scatchard model showed the existence of at least two types of cation complexation site, with strong and weak affinity and negative cooperation. Th4+ was preferentially adsorbed with respect to the other cations, although all species appeared to compete for the same sites independently of bacterial viability. Adsorption of these cations was accompanied by partial release of magnesium from the cell wall, indicating that exchange reactions occurred at magnesium (Mg)-bonding sites