Characterization of Pd(II) biosorption in aqueous solution by Shewanella oneidensis MR-1

Abstract This study investigated the potential ability of Shewanella oneidensis MR-1 to recover palladium ion from aqueous solutions. The effect of pH, initial metal ion concentration, contact time and temperature on adsorption of Pd(II) was investigated. The Pd(II) adsorption properties were analyzed through kinetic, isotherm and thermodynamic models. Furthermore, FTIR, SEM-EDS, TEM-EDS, and XPS were applied to evaluate the Pd(II) adsorption mechanisms onto S. oneidensis MR-1. The kinetic data suited pseudo-second order model, indicating the rate-controlling step was chemical adsorption. The equilibrium data were well fitted to Langmuir isotherm model with maximum Pd(II) adsorption capacity of 158.48 mg/g at 50 °C. The thermodynamic results suggested the Pd(II) adsorption process was exothermic and spontaneous. The results of FTIR, SEM-EDS, TEM-EDS, and XPS revealed both biosorption and bioaccumulation occurred in Pd(II) removal process from aqueous solutions.