Lead, copper and zinc biosorption from bicomponent systems modelled by empirical Freundlich isotherm

The biosorption of lead, copper and zinc ions on Rhizopus arrhizus has been studied for three single-component and two binary systems. The equilibrium data have been analysed using the Freundlich adsorption model. The charact eristic parameters for the Freundlich adsorption model have been determined and the competition coefficients for the competitive biosorption of Pb(II) -Cu(II) at pH 4.0 and 5.0, and Pb(II)Zn(II) at pH 5.0 have been calculated. For the individual single-component isotherms, lead has the highest biosor ption capacity followed by copper, then zinc. The capacity of lead in the t wo binary systems is always significantly greater than those of the other m etal ions, in agreement with the single-component data. Only a partial sele ctivity for copper ions has been obtained at pH 4.0.