Kinetic and equilibrium studies of biosorption of M(II) (M = Cu, Pb, Ni, Zn and Cd) onto seaweed Posidonia oceanica fibers

This work reports the application of Posidonia oceanica for the elimination of heavy metals M(II) (M = Zn, Cd, Ni, Cu and Pb) by biosorption in batch system. The effect of the contact time, initial M concentration, pH and temperature was considered. The kinetic and equilibrium models for the M-biosorption were tested namely the pseudo-first-order, pseudo-second-order and Elovich kinetic models. Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms models have also been used to fit equilibrium adsorption data. The adsorption kinetics follow a pseudo-second-order model for all studied systems, and the equilibrium data are suitably fitted by the above models. The amount of adsorbed metals by biosorption is 48.33, 43.9, 41.02, 37.90 and 30.22 mg/g for Pb(II), Cu(II), Ni(II), Zn(II) and Cd(II), respectively. The thermodynamic parameters suggested that the metal biosorption is spontaneous with an endothermic nature.