Bio-sorption of cadmium and nickel ions using Spirulina platensis: Kinetic and equilibrium studies Original Research Article

The present study dealt with sorption of cadmium (Cd2+) and nickel (Ni2+) ions on Spirulina platensis as a function of contact time, initial metal concentration, and pH regimes. Characterization of this adsorbent was confirmed by FTIR spectrum. Rapid sorption of both metalʹs ions was observed during the first 60 min of contact time and favored at pHi 5. The sorption of these metalʹs ions could be described by Langmuir isotherm that maximum sorptions (73.64 mg g− 1 for Cd2+ and 69.04 mg g− 1 for Ni2+) are related to saturated monolayer of adsorbate molecules on the surface. Sorption kinetics of Cd2+ and Ni2+ ions on S. platensis was better described by pseudo second-order model. This sorption could be explained by the intra-particle diffusion, which was composed of more than one sorption processes. The cyanobacterium showed remarkable performance for removing of Cd2+ and Ni2+ ions as an eco-friendly process.