Equilibrium and kinetics of biosorption of lead(II) from aqueous solutions by Cephalosporium aphidicola

Biosorption of lead(II) onto Cephalosporium aphidicola was examined and the effects of pH, contact time, biosorbent and lead(II) concentrations and temperature on biosorption were investigated. The nature of the possible cell and metal ion interactions was examined by the FTIR technique. The lead(II) biosorption was fast and equilibrium was attained within 30 min. It was found that the overall biosorption process was best described by pseudo-second-order kinetic model. Data obtained from batch studies fitted well with the Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherm models. Maximum adsorption capacity (qmax) of lead(II) onto C. aphidicola was 4.46 × 10−4 mol g−1. The change of free energy, enthalpy and entropy of the biosorption of lead(II) onto C. aphidicola are −1.387 kJ mol−1 at 20 °C, +30.54 kJ mol−1 and +109.43 J K−1 mol, respectively.