Characterization of Heavy Metal Biosorption from Aqueous Solutions with Nitzschia closterium Biomass

The sorption of Cd2+, Ni2+, Pb2+, Zn2+, Fe3+and Cr6+ by a dried diatom Nitzschia closterium was investigated in a batch system. The experiments have been performed for the chosen temperature of 25°C and operational conditions such as constant agitation and pH 5.0 except for Cr6+ at pH 2.0. The sorption of all metal ions rapidly reached equilibrium within 100 min. The maximum sorption capacities of the various metal components on N. closterium biomass could be prioritized in order from high to low as: Pb2+> Cd2+> Ni2+> Zn2+> Cr6+>. Fe3+ where the removal efficiency increased in the order of Zn2+ < Fe3+ < Cr6+ < Ni2+ < Cd2+ < Pb2+. Characterization of the metal-loaded biosorbent by FTIR spectrum confirmed that the metal ions can bind to anionic groups due to electrostatic attraction and sorption capacity is strongly influenced from the type and number of functional groups of the biosorbent