The biosorption of Sr(II) on Bacillus subtilis: A combined batch and modeling study

The batch macroscopic experiments showed that the biosorption kinetics of Sr(II) on Bacillus subtilis can be fitted by pseudo-second-order kinetic model very well, and adsorption isotherms can be satisfactorily fitted by Langmuir model with high correlation coefficient (R2 > 0.995). The independent of ionic strength of Sr(II) biosorption on B. subtilis at pH 2.0-11.0 indicated the inner-sphere surface complexation. The maximum adsorption capacity of Sr(II) on B. subtilis calculated from Langmuir model at pH 5.0 and 293 K was 49.75 mg/g. The fitted results of the surface complexation modeling revealed that the biosorption of Sr(II) on B. subtilis can be simulated by diffuse layer modeling with two inner-sphere surface complexes such as SOSr+ and SOSr(OH)2− species. Theses observation indicated that B. subtilis can be regarded as a promising bio-adsorbent candidate for the preconcentration and immobilization of radionuclides from aqueous solutions in the environmental remediation.