Characteristic features of Bacillus cereus cell surfaces with biosorption of Pb(II) ions by AFM and FT-IR.

In order to elucidate the potential mechanisms involved in the biosorption of metal ions, atomic force microscopy (AFM) and Fourier transform infrared (FT-IR) spectroscopy were used to characterize the interaction between Pb2+ and Bacillus cereus. AFM imaging of the biomass surfaces exposed to different concentrations of lead ions solution showed a major morphological change occurred after Pb2+ biosorption. The FT-IR spectra indicated the binding characteristics of the lead ions involved the carboxyl, hydroxyl and amino groups in the biomass. Equilibrium biosorption experiments of Pb2+ were carried out to investigate the effects of pH values and the initial metal concentrations. The experimental isotherm data were then modeled using Langmuir, Freundlich, and Redlich-Peterson isotherm equations. As a result, the Redlich-Peterson model yielded the best fit of experimental data. Kinetics experiments showed the biosorption was a rapid process and the pseudo-second-order model was successfully applied to predict the rate constant of biosorption.